Patent Application
20200254697
Not applicable
Not applicable
The present invention relates to the bulk bag industry and the art for production of bulk bags without use of sewing machines and stitched seams. The invention further relates to flexible fabric packaging, bags or containers, and the production of flexible fabric packaging, bags or containers without thread contamination and with minimal, or no, human contact with the interior of the packaging, fabric or container to help eliminate concerns regarding bacterial contamination. The invention further relates to production of air tight, or at least nearly air tight flexible fabric packaging, bags or containers that do not contain stitching or sewing holes.
Woven polypropylene fabrics have been the fabric of choice in certain industries, including the bulk bag industry, given the strength, cost and flexibility of the fabrics. In the industry, around 200,000,000 bulk bags are sold each year, but the process of bag construction has remained basically unchanged for about 40 years or more. Although woven polypropylene fabrics and some similar fabrics are very strong, they are also very chemically inert. The polypropylene fabrics are highly oriented through a heating and stretching process to achieve maximum strength while maintaining the needed flexibility of fabrics to fit the needs of the marketplace. Due to these properties, it is very difficult to find a method of connecting two polypropylene fabrics without damaging the fabric itself, thereby reducing notably the strength and usefulness of the fabrics.
The bulk bag industry is now over 40 years old. The very first bulk bags were constructed by combining various configurations of woven fabrics and woven webbing by sewing them together to get the needed strength.
Today, sewing remains nearly the exclusive method for connecting the materials of construction when making bulk bags. The determination of which fabrics to use and which sewing patterns and which threads to use to combine these parts to create the most economical bulk bag container are well known and have been studied in great detail.
However, the basic methods cannot produce the most economical container as the act of sewing reduces the fabric strength through the needle punctures. The average sewn seam in these high strength woven polypropylene fabrics creates seams that are generally about 63% of the strength of the unsewn fabrics.
Therefore, in order for the seams to be strong enough, the fabrics themselves must be constructed thicker and stronger to make up for the loss of strength in the seam.
Many efforts have been made to find an acceptable alternative to sewing polypropylene fabrics for several reasons.
1. The act of sewing creates thread ends that must be cut from the end of each sew line. These ends often get loose and can become unwanted contamination within the bags.
2. Because of the high heat generated by the needles passing through this tough polypropylene fabric, threads are often breaking. This causes production to momentarily stop while the machine is re-threaded.
3. Sewing machines can run at speeds of several thousand stitches per minute. At this high speed with many mechanical parts, there is a high incidence of parts breakage and needle breakage which stops production of that machine while it is repaired.
4. Because of points 2 & 3, the production of bulk bags, for example, requires a high amount of labor to operate these machines and deal with these issues. Global bulk bag production has largely taken place outside the United States, to be produced in countries with abundant sources of low wage labor.
Furthermore, even sewing seams reduce the strength of the polypropylene or other similar fabrics as the needle punctures break the fibers in the area and reduce the fabric total strength. The number of stitches in each inch or centimeter of the seam, the needle size and the thickness of the thread used to make the stitch, all play a part in the overall strength of the resulting seam. Often these seams produce a joint that is about 63 to 70% of the strength of the unstitched fabric. Due to the weakening of the fabrics, fabrics that are 30% stronger than would be theoretically needed to carry the very heavy weights that bulk bags are designed to carry may be used. For all of these reasons, an alternative to sewing has been desired and sought after within the industry for many years.
Thus, for many years, this industry has searched for an alternative to sewing as a method of bulk bag construction. Such diverse methods as chemical bonds, adhesives, solvent glues, laser light sealing, and other forms of known heat sealing have been tried and were unsuccessful.
Various glues and various welding methods have been tried. Generally, contact and solvent glues have been found unsuccessful due to poor peeling strengths, the lack of a permanent and temperature resistant bond, and with low shear strength retention.
For example, contact glues have been found unsuccessful due to:
1. poor peeling strengths,
2. the lack of a permanent bond, (contact glues stay active so they can be peeled and reattached over and over)
3. a bond that is easily affected by temperature changes (glue often melts at very low temperatures and becomes inactive in cooler temperatures),
4. shear strength that is only attained with very large area type coverage. Solvent glues have also failed due to the following:
Heat welding has been tried with polypropylene fabrics and largely rejected because to heat weld as seen in the prior art, one must reach the melting point of the polypropylene fabrics to bond them together. However, the polypropylene fabrics are highly oriented and bringing them up to this temperature level results in a fabric tensile strength loss of approximately 50%.
Laser welding has been tried and showed some marginal success but this method is not economically feasible due to low production rates and very high capital costs.
The basic issue has always been that bulk bags must safely carry tremendous weights, for example in some cases up to 3,300 (1,497 kilograms) or 4,400 pounds (1,996 kilograms) or 5,000 or more pounds (2,268 kilograms). Many prior efforts have shown that joints can be achieved but nothing in the prior art has shown itself to be able to carry the tremendous weights with the required 5 to 1 lifting safety in the resulting containers.
Therefore, after 40 years of production, sewing still remains the basic method of producing bulk bags. Bulk bags are still manufactured largely through the original methods of sewing woven polypropylene fabrics together to form the bag and its lifting components. As discussed above, polypropylene has been the primary fabric of choice due to its combination of strength, flexibility, and cost.
The art of heat sealing is well known in plastic fabric industries such as those industries using polyethylene or PVC fabrics, but as mentioned has largely been rejected with polypropylene fabric. The prior art method has been simple. The prior art process for heat sealing or welding polyethylene has been to heat the fabric up to something higher than the melting temperature of polyethylene then squeeze the fabrics parts together with enough force to squeeze any melting laminated coatings out from between the fabrics and allow the fabrics to join directly together. Heat sealing equipment is useful in that it is significantly more amenable to automation than sewing machines. It has far less moving parts and can be electronically supervised for dependable repeatability.
In the prior art, polyethylene fabrics are heated up past their melting point, then squeezed together with sufficient pressure (for example, 20 psi (137 kilopascal)) to be sure the fabrics meet and join for a pre-determined amount of time, and the joint is made. This joint is typically around 80 to 85% of the original strength of the materials. Since polyethylene materials are not so highly oriented, as compared to polypropylene, this high heat method results in an acceptable joint. In the prior art, pressure may generally be applied at approximately 20 psi (137 kilopascal) across the entire joint area to squeeze the laminations out. Heat is applied at temperatures significantly over the melting point of the polyethylene fabric so that the laminations would become liquefied and the surface of the woven portions would also become melted. The liquefied lamination was then squeezed out from between the fabrics and the melted surfaces of the fabrics themselves were used to make the joint. Example melting points of some polyethylene fabrics may be about 235 or 265 degrees Fahrenheit (112.8 or 129.4 degrees Celsius). High and low density polyethylene fabrics are made in the prior art, and different polyethylene fabrics may have different melting points, wherein low density polyethylene generally has a lower melting point than high density polyethylene. Temperatures, for example, of about 425 to 500 degrees Fahrenheit (218.3 to 260 degrees Celsius) are applied in the prior art to melt the laminated film and polyethylene fabric. Additionally, polyethylene has about 30% less tensile strength than similar sized polypropylene and a great deal greater amount of stretch. Therefore, polyethylene has not been a useful alternative fabric when making bags to carry the great weights of bulk bags (e.g., up to 4,400 pounds (1,996 kilograms), or more).
Polypropylene is so highly oriented that use of current or standard heat sealing procedures, which call for temperatures exceeding the melting point of the fabrics, results in the strength of the fabric itself being immensely deteriorated. Testing conducted with regard to developing the present invention has shown an average loss of tensile strength of approximately 50% when polypropylene fabric is joined through standard heat sealing methods as described above, wherein the fabric is heated to a temperature exceeding the melting point of the fabric. This then results in joint strengths that are significantly less than joint strengths currently available through sewing polypropylene fabrics. Thicker stronger fabrics may then be preferred to be used so that the final strength of a resulting product will safely lift the required weights necessary for the product. Further, such joints produced through heat sealing polypropylene fabric with standard heat sealing methods show a measure of crystallization in the joint area which also reduces the flexibility of the fabrics in the joint areas.
There is a need in the industry to produce products comprising polyethylene fabrics with stronger heat sealed seams or joints than what is achieved by prior art methods of heat sealing polyethylene fabrics.
There is a need in the industry to produce products comprising polypropylene fabrics, including fabric bulk bags, by sealing, instead of stitching the parts or fabric pieces together, given that needles break frequently and sewing requires an operator to replace the needle and repair the stitches that were not properly applied.
There is also a need in the industry to produce products comprising polypropylene or polyethylene fabrics, including fabric bulk bags, by sealing, instead of stitching the parts together. Use of sewing machines for bulk bag production, for example, involves high amounts of labor, thread contamination will always be a possibility and powders sifting through the sewn seams will always be a concern.
While sewing machines might be able to be automated, they have not been able to run in an automated manner. Threads break as heat builds up, and an operator is needed to re-string the machine with new thread. These machines operate at high speeds and often skip stitches. This requires an operator to see this quality issue and repair it right away.
The following prior art references are incorporated herein by reference.
As discussed above, bulk bags, a commonly used name for Flexible Intermediate Bulk Containers (FIBCs), have been in use since sometime in the 1970's. They are well known as large bags made of woven polypropylene designed to lift and carry loads from about 500 to 5,000 pounds (226.8 to 2,268 kilograms).
For their entire known history, such bags generally have been fabricated by cutting woven polypropylene fabrics to needed sizes and then sewing the pieces together in a fashion that will give them adequate size and strength to carry the heavy loads discussed above. Woven polypropylene, e.g., highly oriented woven polypropylene, has been the material of choice due to its strength, low cost and its inertness to almost every dry chemical that might be transported in it.
However, due to being so inert, the only prior art way for commercially constructing the bulk bag has been to physically connect the pieces by sewing them together with needle and threads.
For 40 years, other forms of construction have been tried and found unable to meet the shear strength needs of this package, used to carry about 500 to 5000 pounds (226.8 to 2,268 kilograms) of bulk material, in a commercially viable manner. Therefore, all bulk bags being made to this day have stitching holes on every seam with threads passed through these stitching holes.
These stitch holes are points of entry and exit by the hundreds in every bulk bag. If the product within the bag is made of fine powders, these powders often leak through the stitch holes causing local contamination and the need for cleanup. If the product is also hazardous, this can cause great expense and concern for those who have to handle and clean up the leaking powders.
Another concern with stitched polypropylene fabric bags and bulk bags is their ability to control moisture. Each stitching hole in the fabric is a break in the barrier to moisture entering or leaving the bag and the product within. Increases in moisture often can devalue the product within. Therefore many bags need an extra moisture barrier such as a polyethylene film liner to be added within the bag. This adds cost and complexity to each such bag.
The present invention solves these problems created by stitch holes in a very direct way by eliminating any stitching holes in the product containment area of the bulk bag. Embodiments of the present invention provide an entirely stitchless bulk bag, e.g., for carrying bulk product weighing about 500 to 5000 lbs (226.8 to 2,268 kilograms).
Other embodiments of the present invention provide an entirely stitchless bulk bag at least in a containment area of the bulk bag, e.g., in areas that can come into contact with bulk material to be held or contained in the bulk bag.
Further, when sewing these bulk bags together, as done in the prior art, there are many stop and starting points to the sewing process. At each of these points, threads are cut so the sewing machine can be re-positioned. These cut threads leave long tails of threads attached to the bags. These long threads are often considered as sources of contamination or as aesthetically displeasing. They are then cut off and often become a true source of contamination as a loose thread within the bag. One or more embodiments of the present invention solve this contamination problem by eliminating all sewing in the product containment area, and providing a bulk bag without any stitches in the containment area.
Another advantage to the present invention is the reduction of fabric weight needed in the seam areas. In the prior art, each needle puncture of the fabric causes a weakening of the fabric. The yarns making up the fabric are punctured (damaged) making the sewn fabric weaker than the unsewn fabric. Because of this, the unsewn fabrics must start out heavier so that the sewn fabric will have enough strength left to carry the weight and needed safety levels, e.g., the current 5 to 1 lifting standard in the bulk bag industry. Various embodiments of the present invention solves this problem in a very direct manner by eliminating any puncturing or weakening of the fabric in any seams involving the product containment area, which enables production of bulk bags, e.g., for carrying about 500 to 5000 lbs (226.8 to 2,268 kilograms) of bulk material, with lighter fabric than what is used in the prior art.
Another advantage of the present invention is its ability to be automated, i.e., automating the production of bulk bags. The average sewn bulk bag requires about 600 inches (1,524 centimeters) of sewing. During this time, the bag must be manually moved through a series of directions and steps to put the stitches in the most useful position. Further, when moving at a high speed to construct the bulk bag, the friction between the polypropylene fabric and the needle often reaches a temperature high enough to either melt or weaken the thread to the point of breaking. This causes the operation to stop and the need to manually rethread the needle of the sewing machine. Due to all the changes in direction and the customizing of every bag, no one has ever successfully automated the sewing of the bulk bag. The present invention solves this issue by working with the bulk bag fabrics in a simple 2-dimensional condition and using a specially designed set of heating elements to bond the coatings of the fabrics together. This bonding action is accomplished using simple equipment in simple up and down motions on the 2-dimensional form of the bulk bag being manufactured.
In various embodiments of the present invention the bonds generally have at least about a 90% bonding efficiency which allows for lighter fabrics to be used. The bag design allows the bonds to be made in minimal numbers of straight line seams that can be made in minimal steps. This allows automation to be applied in various embodiments of the method of the present invention to the manufacture of the stitchless bulk bag of the present invention.
Another gain in the present invention is the ability to monitor the creation of each bond of the bulk bag through computer analysis. This provides greater repeatability and therefore a higher level of safety to the end user than can be presently created with individually hand sewn bulk bags. In the prior art of sewing, the damage occurring to the threads during the sewing process is not measured, nor is the tension of each stitch measured. Both of these conditions are important to the overall safety of each bulk bag during the lifting process. Since they are not measured, the manufacturer must increase the amount of thread being used to overcome these unknowns. In one or more preferred embodiments, this problem in the prior art is being overcome in the present invention by utilizing at least double monitoring of the critical controls needed to be assured that each and every seal is being properly controlled by the computers. In other embodiments additional critical controls may also be used, e.g., triple monitoring controls.
Another part of the present invention in various embodiments is the elimination of the need to reinforce the part of the bag to which the lifting loops are sewn. In the prior art, the attachment of the lift loops involves a lot of stitching in select areas of the fabrics. This amount of stitching to allow the bag to be safely picked up has the effect of weakening this critical part of the fabric. Therefore, the prior art is prone to increasing the number of yarns in the loop attachment area either by process in the weaving or by folding the fabric over at this lift loop attachment point to place more fabric under the stitches to create safe lifting capacity. One or more embodiments of the present invention eliminate this need by eliminating the stitching of the loops to the bag body, by stitching the loop to another panel of woven fabric with a coating that can then be heat sealed to the bag which can provide about 90% or more of the original fabric strength in the bonded condition.
Another advantage provided by the present invention is the additional safety given to the product in the event mishandling of the bulk bag occurs. In the prior art, if a bag was improperly handled by less than all four lift loops, the lift loops often tear away from the bag by pulling and breaking portions of the side wall from the bag. This causes large holes in the bulk bag product containment area allowing the product to spill out of the bag and/or contamination to enter the bag. This often causes the loss of the product that was being transported in the bulk bag. If the product was considered to be hazardous, then a spill containment action would be needed. In one or more preferred embodiments of the present invention, this problem is solved by adding the lift loops to the bulk bag on a separate piece of fabric that can tear away from the bag, e.g., given any improper handling of the bag, without damaging the sidewalls of the bulk bag, allowing the product to remain safely contained within the bag with no leakage.
Another novel feature of the present invention is the ability to utilize seamless and stitchless tubing for fill and discharge spouts without changing the critical diameter of the spout during the attachment of the tie cord. In the prior art, tie cords are attached by pinching an edge of the tube and sewing the tie cord to it. This pinching and sewing causes the original diameter of the tube to be reduced in that sewn area. This pinched area then causes difficulties in placing the pinched tube onto the filling machines that are designed for the diameter of the original fabric spout.
A second way the prior art attaches a tie cord is to slide an open end of the tube onto the throat of the sewing machine and apply a small stitching pattern to attach the loop. This leads to potential contamination from oil or threads because of the machine entering this part of the bag.
Both of these method problems experienced in the prior art are eliminated in a straight forward and simple manner in the present invention. By recognizing that there is little need for strength in the anchoring of this tie cord, in one or more preferred embodiments of the present invention, the sewing is replaced with a simple longitudinal or vertical piece of tape placed over the tie cord which is preferably attached in a lateral or horizontal position. During the tie off procedures, the longitudinal or vertical tape is not challenged during the lateral or horizontal tying of the cord to restrict the tube from product flow.
Another problem experienced in the prior art is the positioning and securing of a clear document pouch on the bulk bag. The bulk bags often need to be accompanied by product information such as manufacturing date, product name, lot number, etc. So a document pouch is typically provided to contain, carry and present this information to the receiver of the filled bulk bag.
Again, due to the inertness of the polypropylene fabric, the manner of attachment of a document pouch has been to sew an edge of the document pouch in one of the seams of the sewn bulk bag. The most commonly used seam was a seam that attached the top of the bag to the side of the bulk bag. This then allowed the pouch to be ‘buried’ between the top of the bag it is sewn to and the bottom of the bag that is stacked upon it.
Since many FIBCs are not filled to the top, the document pouch often ends up laying in a horizontal position on top of the product and is unreadable by the forklift driver while in his seat. This then causes the driver to leave his machine to read the documents.
In one or more preferred embodiments of the present invention, this problem encountered with document pouches is solved by attaching the label through heat welding or sealing or fusion. When attached with heat, it can be placed nearly anywhere on the vertical side of a bag without needing a relationship to a sewn seam or bag edge. By design, this pouch can now be positioned low enough on a side wall to always be readable by the forklift driver without him having to leave his seat on the forklift. Another novel feature of one or more embodiments of the present invention is that thick lifting loops that have to be attached through sewing in the prior art, are replaced, using bag fabric to replace the loops. By eliminating the sewing, the bag becomes more amenable to recycling because the lift loops are often sewn in the prior art bags and contain polyester threads which are considered to be a form of contamination in the recycling effort for FIBCs.
Another issue solved by the stitchless designed bulk bag in various embodiments of the present invention is the strengthening of the failure point experienced in one and two loop design bags. These designs are well known in the art and have been considered the most efficient bag design in the market. Since it uses all the vertical fibers in the bag body to securely lift the weight, this design often uses a lighter weight of fabric than traditional four loop bags. However, even this efficient design is hampered by the loss of strength in the sewn seam in the prior art. The present invention, by strengthening the seam strength, e.g., with heat fused or welded or sealed joints instead of stitched seams, is able to lower the overall fabric strength even more and achieve similar lifting safety.
Another issue resolved by the stitchless bulk bag of present invention is the ability to eliminate the liner needed to secure the product in one and two lift loop bags. Due to the highly efficient bonding strength of the stitchless bag invention, the liner can be replaced with a spouted top. This is desirable as the liner often poses problems during product discharge in the prior art. Since the liner is used for product protection from water, only the stitchless design with a fully enclosed top spout can adequately protect the product without a liner. Prior art sewn bags continually puncture the fabric and the moisture barrier and further, as stated above, weaken the fabric as well.
Another important problem experienced in the FIBC industry that the stitchless bag solves is the contamination and leakage issue that baffled bulk bags have. Baffled bulk bags have a fabric structure sewn across the corners on the inside of the bulk bag. These corners restrict the sides of the prior art baffled FIBC from rounding out to their full diameter thus giving this design a much squarer looking shape. These bags are well known in the prior art. But, in the prior art process of sewing these cross corner panels inside the bag, the sewing machines are working inside the bag. This increases the potential of threads being left inside the bag as well as oil residue being atomized and clinging to the interior surface of the bulk bag in the product containment area of the bag.
Also, every stitch hole is an additional opportunity for leakage of the product over and above those opportunities created in the making of a standard bulk bag. The baffle bag has 8 additional vertical stitch lines that are created to attach the four corner panels. In a common size, such as about a 50 inch (127 centimeter) tall bag, this would equal about 8×50 or 400 additional stitching inches. The average stitching pattern is about 3 stitches per inch (7.62 centimeters) or about an additional 1200 stitching holes in every baffled bag. This is 1200 additional chances for product leakage or moisture contamination.
The stitchless bag of the present invention solves these problems in a straightforward way. In preferred embodiments, all interior panels are sealed from the outside. By sealing the interior panels from the outside, all of the stitching holes are eliminated and all contamination by thread or by machine oil is eliminated.
As discussed, the apparatus, system and method of the present invention solves the problems confronted in the art in a simple and straightforward manner. What is provided is one or more alternative methods of connecting woven polypropylene fabrics, or similar fabrics, without the use of sewing machines and sewing threads. Also provided are one or more methods for connecting polyethylene fabrics without use of sewing machines and sewing threads. Various embodiments of the present invention are useful in the production of bulk bags, e.g., bags that can carry about 500 to 5000 lbs (226.8 to 2,268 kilograms) of bulk material, and also will apply to any product for which one wishes to connect polypropylene fabrics, polyethylene fabrics, or similar fabrics without the use of sewing machines. This invention also relates to the ability to produce products involving connecting polypropylene fabrics or similar fabrics, including bulk bags, with minimal labor, thereby allowing such products to be made in all areas of the world where the products are needed, versus only being produced in volume in those areas of the world with large amounts of low wage labor.
An object of the present invention is thus to provide an alternative to sewing polypropylene or other similar fabrics in producing bulk bags and other flexible fabric products or containers. The present invention seeks to provide an alternative method of connecting woven polypropylene fabrics or similar fabrics without the use of sewing machines and sewing threads. While this invention is useful in the production of bulk bags, it also can apply to any product that wishes to connect polypropylene fabrics or similar fabrics without the use of sewing machines. For example, the present invention can also be useful with smaller bags (e.g., for holding about 25 to 100 pounds (11 to 45 kilograms)).
Another object of the present invention is to design a sealing system that can utilize simple robots for automation in the construction of flexible fabric containers.
It is a further object of the present invention that a flexible fabric bag or product made by heat sealing versus sewing will have many advantages as follows: lower wage content, reduced or eliminated sewing thread contamination, no needle holes to allow sifting of product out or moisture and contamination in, a more consistent quality control, controlled by computerized production rather than being hand made with all the attendant consistency issues such a handmade method creates.
It is a further object of the present invention that the flexible fabric products made by heat sealing will have great marketplace appeal for those companies for whom any thread contamination would jeopardize the quality of their product. Such companies include in the food, electronics, medical, or pharmaceutical industries. These bags would have no threads or sift holes to endanger things, such as the product or the workers as there would be no sewing.
It is a further object of the present invention to provide a flexible fabric product has great appeal to those companies who are concerned about sifting of their product through the needle holes left by the sewing process. Such companies may include the carbon black companies, where very tiny amounts of their product can make very large messes. Other companies may include companies whose products are going into sensitive end user environments where small amounts of their products would contaminate the area.
It is a further object of the present invention to provide a flexible fabric product that would not require a liner, e.g., a polyethylene liner. This would be useful for companies who are using polyethylene liners to prevent sifting and contamination. Liners make bulk bags, for example, more difficult to work with and add a notable amount of cost to the overall product.
It is a further object of the present invention to provide a method that allows companies to pursue full automation for woven fabric product or bag production.
It is a further object of the present invention to provide a method that allows companies to pursue at least partial automation for woven fabric product or bag production.
It is a further object of the present invention to provide a method that allows companies to pursue automation for woven fabric product or bag production with regard to at least a majority of the bag production process.
It is a further object of the present invention to provide heat sealed joints with minimal damage of the original fabric for allowing lower costs through facilitating automated production to reduce labor costs, and also facilitating reduction of fabric weights and thicknesses while providing similar overall strengths through higher seam efficiencies.
It is a further objective of the present invention to use heat sealing equipment, which can be automated, to produce polypropylene products without requiring stitched seams or sewing machines. It is also an objective of the present invention to use heat sealing methods to produce products comprising fabrics similar to polypropylene, without requiring stitched seams or sewing machines.
Another objective of the present invention is to facilitate a robotic or automated system for production of large fabric bags, for example polypropylene bulk bags or barrier cells, for forming a flood barrier, for example, when filled with sand or the like, using robots or other automated system.
A further objective of the present invention is to provide a heat sealed polypropylene product that may be manufactured without human touch on the inside of the product, so as to maintain a sterile product and help eliminate concerns regarding bacterial contamination of polypropylene storage products, as well as to eliminate the possibility of leakage through sewing holes, so that the product may be used in medical applications, for example, in the pharmaceutical industry.
Another object of the present invention is to include different seam configurations that would always have shear strength working for the seam. An object of the present invention is also to include a seam that will work in both directions.
In developing the present invention, testing and experimentation was conducted. For example, testing and experimentation with heat sealing polypropylene fabric was conducted. Test results showed that these fabrics are highly oriented for strength. This high orientation and the molecular structure of polypropylene made efforts to connect two pieces of this material difficult. To join polypropylene pieces of fabric required such a level of heat that the polypropylene fabric simply crystallized making it brittle and not helpful for the purpose of lifting great weights, a purpose for which bulk bags, for example are routinely used.
Besides crystallizing the fabric, heat sealing polypropylene fabric using standard procedures known in the art resulted in seams with two distinctly different strengths. In seaming operations, including when sewing, there exists a “shear strength” and a “peel strength”. For example, the lift loops sewn to the side walls of a bulk bag have amazing strength when pulled straight up as this motion utilizes the shear strength of this joint, where the entire joint is sharing the load at all times. But if the bag is lying on its side and it is picked up by one loop, the joint is temporarily put into a position where the peel strength becomes critical, where one edge of the joint is attacked. Thus in shear strength position, the entire joint is sharing the load at all times. In the peel strength position, only one edge of the joint is attacked or bearing the load. As that edge fails, the next edge and then the next edge fail in sequence.
This peel versus shear strength issue was considered when experimenting with heat sealing polypropylene fabric, for constructing bulk bags for example, because any interior panel that may be installed via heat seal in a bulk bag may be attacked by fill material weight from either side. It is also difficult to control all filling situations in the field.
When testing panels for inside a fabric container, for flood wall use for example, an upside down “T” shape seam construction was developed and used. Testing revealed that if the force came from the right side of the ‘T’, the right side of the seal or joint would be in shear and the left side would be in peel. But the right side would protect the left side with all of its shear strength. If the load or force came from the left side, the seam would work in reverse with the shear strength on the left protecting the peel on the right.
Another object of the present invention is to provide a heat sealed bulk bag without damaging the bag fabric or weakening the bag fabric.
In further testing conducted with polypropylene fabrics, different glues were tested for making usable joints with polypropylene fabric. Test results using Super Glue showed that Super Glue did not achieve about a 20 pound (9 kilogram) shear strength.
Testing was also conducted using different types of fabric. Polyethylene fabric is similar to polypropylene but is not as highly oriented and many products comprising polyethylene have been made using standard heat sealing methods.
Testing and experimentation with polyethylene fabric showed that polyethylene fabrics were generally about 30% weaker than polypropylene fabrics. Testing was performed with regard to heat sealing polyethylene fabric to produce a bulk bag. As previously discussed, polypropylene fabric has been preferred in the bulk bag industry given its higher strength.
As discussed, prior art methods of heat sealing generally involve high enough heat and high enough applied pressure to melt the basic fabrics and join them together. This method purposefully, melts any applied coating and squeezes it aside through the high pressure levels so that the base woven materials can be joined together. This method has been successful, with polyethylene fabrics and was necessary because the strength being relied upon came from the woven fabrics. The coatings were generally applied for the purpose of providing dust and/or moisture control. The technology at the time for applying the laminations did not provide dependably strong attachments of the coating to the fabric itself. Therefore, the art of joining the fabrics intentionally melted away the laminated materials by melting them and squeezing them out from between the fabrics.
In the prior art, the standard method discussed above has been applied to woven fabrics that have a thin layer of laminated film on at least one side, for example about a 1 or 2 mil (0.0254 or 0.0508 mm) layer. For polyethylene fabrics, standard laminated film or coating is often comprised of polyethylene, or a mixture of polyethylene and other additives. Standard prior art methods apply pressure to squeeze the laminated film or coating out from between the layers of polyethylene fabric, to allow the fabric pieces to melt and join together. Traditionally in the art, the laminated film or coating was not very securely attached to the woven fabrics. Therefore, if the joint included the laminated film itself, the lamination became the cause of the joint failure because of its weak attachment to the woven fabrics.
To determine a joint strength, laminated woven fabrics may be tensile tested before being joined to get a baseline strength of fabric. For example, a fabric may break at about 200 lbs per inch (3,572 kilograms per meter) in its raw state. Then two pieces of this fabric may be joined and then pulled to destruction again. A resulting strength, for example, of about 160 to 165 pounds per inch (2,857 to 2,946 kilograms/meter) would mean that a resulting joint would have lost about 17 to 20% of the total fabric strength as a result of being sealed together. While this joint strength may be sufficient based on current industry standards, it still represents a significant cost of inefficiency.
In an embodiment of the method of the present invention, the method provides a heat fused joint between pieces of polyethylene fabric by joining the laminations or coatings rather than by joining the fabrics. Current laminating methods now produce a cling or connection rate between the woven fabric and the lamination that is very strong and dependable. By leaving the lamination in place between the fabrics and not joining the fabric pieces, the improved sealing method of the present invention adds the strength of the lamination to the total strength of the joint. Additionally, since the method of the present invention does not damage the fabric by melting the woven portions, the sealed joint retains virtually all of the base woven fabrics strength. The small percentage of strength lost, for example two or three percent of strength that may be lost, is the result of minimal damage to the laminated film through melting and fusing that occurs in the present method.
In the prior art heat sealing or welding methods, pressure may generally be applied at approximately 20 psi (137 kilopascal) across the entire joint area to squeeze the laminations out. Heat is applied at temperatures significantly over the melting point of the polyethylene fabric so that the laminations would become liquefied and the surface of the woven portions would also become melted. The liquefied lamination was then squeezed out from between the fabrics and the melted surfaces of the fabrics themselves were used to make the joint. Example melting points of some polyethylene fabrics may be about 235 or 265 degrees Fahrenheit (112.8 or 129.4 degrees Celsius). High and low density polyethylene fabrics are made in the prior art, and different polyethylene fabrics may have different melting points, wherein low density polyethylene generally has a lower melting point than high density polyethylene. Temperatures, for example of about 425 to 500 degrees Fahrenheit (218.3 to 260 degrees Celsius) are applied in the prior art to melt the laminated film and polyethylene fabric.
An embodiment of the method of the present invention comprises joining polyethylene fabrics using controlled heat, time and pressure amounts that leave the base or woven materials unmelted and undamaged yet still melt the laminations or coatings. The pressure levels are preferably kept light enough to leave the lightly melted lamination in place rather than to purposefully squeeze it out from between the woven portions of the joint.
Another embodiment of the present invention comprises a method of heat sealing polyethylene fabric comprising joining polyethylene fabrics using controlled heat, time and pressure amounts that leave the base or woven materials unmelted and undamaged yet still melting the laminations.
In another embodiment of the method of heat sealing polyethylene fabric, the pressure levels are kept light enough to leave the lightly melted lamination in place rather than to purposefully squeeze it out from between the woven portions of the joint, e.g., pressure of 2 to 6 psi (13.8 to 41.4 kilopascal) can be utilized.
In another embodiment of the method of heat sealing polyethylene fabric, seals provide about 90% to 97% joint strengths in the shear direction.
In another embodiment of the method of heat sealing polyethylene fabric, the seal comprises a strength of about 92 to 95%.
In another embodiment of the method of heat sealing polyethylene fabric the seal comprises a strength of about 96 to 97%.
In another embodiment of the method of heat sealing polyethylene fabric, the method comprises heating a laminated film or coating on polyethylene fabric pieces right at or barely above the melting point of the polyethylene fabrics so that only the lamination is melted and liquefied. Then light pressures, for example about 5 to 6 psi (34 to 41 kilopascals), are used to join the laminations of the fabric pieces together, rather than to push them away and join the underlying fabrics. In another embodiment of the method of heat sealing polyethylene fabric, the method provides a heat fused polyethylene seal or joint with about 90 to 97% strength, as compared to the strength of the original fabric.
Another embodiment of the present invention comprises heat fusing polyethylene fabrics to produce a bulk bag. In an embodiment of the polyethylene bulk bag of the present invention, the bag would not include lift loops but would include fabric tunnels which would use the strength of the entire bag fabrics for lifting versus the lift loop bags that use only a small portion of the fabric for lifting. Testing results for an embodiment of the present invention, showed that a heat sealed bulk bag built out of polyethylene fabric held over 18,000 lbs (8,165 kilograms) of hydraulic pressure before failing. On a 5 to 1 safety ratio, this bag could be useful for applications that carry up to about 3600 lbs (1,633 kilograms). In this embodiment, the method used all of the fabric on two sides of the bag. Further, the fabric was doubled so the heat seal would be on the bottom of the bag and protected from any potential peeling forces. Although the heat fused polyethylene bag had nearly 50% more materials, this embodiment of the bag, still eliminated a lot of the labor associated with producing fabric bulk bags via sewing methods.
In another embodiment of the method of heat sealing polyethylene fabric, impulse heat sealing equipment is used to deliver controlled amounts of heat for controlled amounts of time to specified portions of the fabric which result in about a two inch (5.08 centimeter) wide seal. In another embodiment of the method of heat sealing polyethylene fabric, these seals provide about 90% to 97% joint strengths in the shear direction.
In another embodiment of the method of heat sealing polyethylene fabric, heat sealing equipment may be automated, and sensors can be attached to monitor time, heat, and pressure. These readings can transfer to a watch station in a control room. Robots can move the materials from work station to work station and fabric can be positioned and sealed robotically.
In another embodiment of the method of heat sealing polyethylene fabric, using relatively low heat and low pressure, only the coating itself is being joined. This leaves the fabric completely undamaged and unweakened. In fact, the strength of the coating now adds to the overall joint strength rather than being squeezed out in the current methods. With the resulting joint strengths, one is now able to lift greater weights with less material than can be done with the current, commonly used methods of sewing fabrics together.
When developing an embodiment of a heat sealed polyethylene bulk bag, the following factors were considered. First, there are many changes in direction and different or special shapes for heat sealing equipment that may be needed for production of bulk bags. Second, safety levels for polyethylene bulk bags would preferably be similar to the safety levels of polypropylene fabric bulk bags, which are about 30% stronger.
When testing an embodiment of a heat sealed polyethylene bulk bag, the results showed about 93% joint efficiency.
In an embodiment of a polyethylene bulk bag of the present invention, the lift loops were eliminated and replaced with fabric tunnels which would use the strength of the entire bag fabrics for lifting versus the lift loop bags that use only a small portion of the fabric for lifting.
Experimental models were constructed to identify and evaluate any practical issues. In one embodiment, test results showed that a heat sealed bulk bag built out of polyethylene fabric held over 18,000 lbs (8,164 kilograms) of hydraulic pressure before failing. On a 5 to 1 safety ratio, this bag could have been sold for applications that carried up to about 3,600 lbs (1632 kilograms). In this embodiment, the method used all of the fabric on two sides of the bag. Further, the fabric was doubled so the heat seal would be on the bottom of the bag and protected from any potential peeling forces. This meant that the heat fused polyethylene bag had nearly about 50% more materials. This embodiment of the bag, however, still eliminated a lot of the labor associated with producing fabric bulk bags via sewing methods.
An embodiment of the method of the present invention is a method to produce bulk bags or any flexible fabric container comprising polypropylene fabrics in a manner that can result in joints that are heat sealed in such a manner that the natural stresses on each heat sealed joint will be applied to the joint or seam in the shear direction for the greatest strength.
One or more preferred embodiments of the method of producing polypropylene bulk bags, e.g., highly oriented polypropylene fabric bulk bags, would utilize a fusion or bonding or sealing coating on at least one surface of a fabric layer to be heat-fused to another fabric layer. As used herein, a fusion or bonding or sealing coating can mean a coating comprising propylene based elastomers or plastomers. In various embodiments, the fusion or bonding or sealing coating can comprise about 50% to 90% of propylene-based plastomers, propylene-based elastomers, or mixtures thereof and about 10% to 50% polyethylene resins and additives, having a melting point that is preferably at least about 5 degrees lower than the melting point of the polypropylene fabrics to be joined together. In other embodiments, the fusion or bonding or sealing coating can comprise about 50% to 90% of VERSIFY™ 3000 (Trademark of The Dow Chemical Company) and about 10% to 50% polyethylene resins, having a melting point that is preferably at least about 5 degrees lower than the melting point of the polypropylene fabrics to be joined together. Suitable propylene based elastomers or plastomers can be purchased for example under the trademark VERSIFY™ 3000, and EXXON™.
In various embodiments a mixture of a minimum of about 70% pure VERSIFY™ 3000 and about 25% polyethylene, and about 5% other additives such as pigments or Ultra Violet (UV) inhibitors, can be used for a bonding or sealing or fusion coating. Other potential additives may include anti-static protection. Properly sealed, this system will produce heat sealed joints resulting in an average joint strength of about 92% of the strength of standard 5 ounces per square yard (169.53 grams per square meter) woven polypropylene.
Another embodiment of the present invention comprises a method of joining highly oriented polypropylene woven fabrics by the following steps: coating the fabrics with materials, wherein one piece of fabric to be joined is coated with materials comprising VERSIFY™ 3000, which has a melting point lower than the polypropylene fabric, and wherein the other piece of fabric to be joined is coated with a standard industry coating; heating the coating comprising VERSIFY™ 3000 to its lower melting point; and joining the coatings with pressure light enough to allow the coating to stay in place and generally keep the woven fabrics from touching.
Another embodiment of the present invention comprises a method of joining highly oriented polypropylene woven fabrics by the following steps: coating the fabrics with materials, wherein one piece of fabric to be joined is coated with a propylene based elastomers or plastomers coating, e.g., a coating having about 50% to 90% of propylene-based plastomers, propylene-based elastomers, or mixtures thereof and about 10% to 50% polyethylene resins and additives, and having a melting point that is preferably at least about 5 degrees lower than the melting point of the polypropylene fabrics to be joined together, and wherein the other piece of fabric to be joined is coated with a standard industry laminate coating; heating the coating comprising propylene based elastomers or plastomers to its lower melting point; and joining the propylene based elastomer or plastomer coating and standard industry coating with pressure light enough to allow the coatings to stay in place and generally keep the woven fabrics from touching.
In an embodiment of the present invention, the strength of the coating adds to the overall joint strength, and resulting joint strengths, allows one to lift greater weights with less material than can be done with the current, commonly used methods of sewing fabrics together.
In another embodiment of the present invention, a coating comprising a suitable percentage of VERSIFY™ 3000, or other suitable propylene elastomer or plastomer coating with a melting point lower than the melting point of the polypropylene fabrics, will be applied on at least one side of one piece of polypropylene fabric and a standard industry coating will be applied to at least one side of another piece of polypropylene fabric. Standard industry coatings for polypropylene fabric generally comprise a majority percentage of polypropylene and a small percentage of polyethylene, e.g., 15 to 30 percent. The piece of fabric comprising the VERSIFY™ 3000 coating, or other suitable propylene elastomer or plastomer with a melting point below the melting point of the polypropylene fabric, will be positioned to overlap the piece of fabric comprising the standard coating, and positioned so that the coating layers are in contact. Low heat and low pressure, e.g., about 221 to 290 degrees Fahrenheit (105 to 143 degrees Celsius) and 2 to 6 psi (13.8 to 41.4 kilopascal), will be applied to melt the coating and form a joint between the coatings of the polypropylene fabric. This embodiment of the present invention is cost effective because standard coatings cost less than coating comprising VERSIFY™ 3000, for example.
Testing results have shown similar seam strengths when joining one fabric comprising a VERSIFY™ 3000 coating and joining another fabric comprising a standard coating. A notable amount of money may be saved as the standard coating is far less expensive. In a preferred embodiment, both the VERSIFY™ coating, or other suitable propylene elastomer or plastomer coating with a melting point below the melting point of the polypropylene fabrics, and the standard coating will be applied to about a 2.5 mil (0.0635 mm) thickness. In a preferred embodiment of the present invention, the coating is applied at about a 2.5 mil (0.0635 mm) thickness. Generally in the prior art, standard industry coatings are applied at about 1 mil (0.0254 mm) thickness.
In another embodiment of the present invention coatings will be applied to the fabrics at a thickness of about 1 mil to 2.5 mil (0.0254 to 0.0653 mm).
In one or more embodiments of the present invention coatings can be applied at over 2.5 mil (0.0635 mm) thickness.
In one or more embodiments of the present invention coatings can be applied at less than 2.5 mil (0.0635 mm) thickness.
In one or more preferred embodiments, a coating on one fabric portion, e.g., a body fabric portion, can be applied at one thickness, while the coating on a different fabric portion, e.g., the bottom, can be applied at a different thickness.
In various embodiments it can be desirable to apply a thicker coating on fabric portions that will form a bond that will need to withstand a greater load of weight or pressure, e.g., a bottom portion can have a thicker coating than a top portion.
In various embodiments a coating, e.g., a bonding or a standard coating can be applied at 2 to 5 mil thickness (0.05 to 0.13 millimeters).
In an embodiment of the method of the present invention, the method is for creating a new form of heat welding seam for polypropylene fabrics that provides as high as about 95% seam strength in the shear position. An objective of the present invention is to use that seaming method to create a safely improved bulk bag that is competitive in the marketplace.
Another embodiment of the method of producing flexible fabric bags, comprising the steps of coating a polypropylene fabric with 100% VERSIFY™ 3000 or a combination VERSIFY™ 3000 and polyethylene, and joining the fabrics (not specifically just edges) using a combination of heat and minimal pressure in such a manner that only the coatings are welded together and not the fabrics. Thus producing a joint that will have a strength greater than the original uncoated fabric.
An embodiment of the method of the present invention comprises using heat to combine the laminated coatings of the fabrics versus trying to combine the fabrics themselves. Since the coatings have a marginally lower melting point then the fabric itself, this invention joins polypropylene fabrics without damaging the tensile strength of the original fabrics.
In one or more embodiments of the present invention, impulse heat sealing equipment is used to deliver controlled amounts of heat for controlled amounts of time to specified portions of the fabric which result in about a 2 inch (5.08 cm) wide seal. In an embodiment of the present invention, these seals provide about 85% to 96% joint strengths in the shear direction.
In various embodiments, the amount of heat and pressure applied to form one bag joint can be different from the amount of heat and pressure applied to form another bag joint.
In an embodiment of the present invention, heat sealing equipment may be automated, and sensors can be attached to monitor time, heat, and pressure. These readings can transfer to a watch station in a control room. Robots can move the materials from work station to work station and fabric can be positioned and sealed robotically. In other embodiments, materials can be moved from work station to work station manually or by hand, or with a combination of automation and manual movement.
An embodiment of the method of the present invention enables production of a robotically manufactured bulk bag that has very little labor, wherein the bulk bags will not have human touch on the inside of the bag so as to prevent human bacteria contaminations.
An embodiment of the present invention comprises a robotic or automated system for production of large fabric bags, for example polypropylene bulk bags or barrier cells, for forming a flood barrier, for example, when filled with sand or the like using robots or other automated system.
Another embodiment of the present invention comprises a simple robotic or automated system that may fit into about a 40 foot (12.2 meters) export container, or other suitable transportation means, that one could then take to any potential flood site or project site and start producing about 500 foot (152.4 m) lengths of fabric bags or containers or cells on site, for example. The robotic or automated system would be similar to a system used to make endless rain gutters for homes and apartments, for example. In another embodiment of the present invention, the automated or robotic system would also enable production of other polypropylene or similar fabric products on site, in various length measurements as may be suitable for a particular purpose or project.
In another embodiment of the present invention, what is provided is a method of producing flexible fabric bags, comprising the steps of coating polypropylene fabric portions with a combination of VERSIFY™ 3000, or other propylene elastomer or plastomer coating, with a melting point below the melting point of the polypropylene fabric, and polyethylene; wherein each fabric piece has a coated side and an uncoated side; positioning fabric pieces so that a coated side of one fabric piece faces a coated side of another fabric piece, selecting an area of fabrics to be joined for forming one or more seams or joints and applying heat to the coated fabric at the joint area under a pressure of area to be joined that is less than about 2 psi (13.8 kilopascal), to form a joint with at least about a 90% joint efficiency in a joint tensile test.
Another embodiment of the method of producing flexible fabric bags, comprises the steps of coating a polypropylene fabric with a combination of VERSIFY™ 3000, or other suitable propylene elastomer or plastomer with a melting point below the melting point of the polypropylene fabric, and polyethylene; joining edges of the coated fabric, by applying heat to the coated fabric at the joint location under a pressure of less than about 2 psi (13.8 kilopascal), to form a joint with at least about a 90% joint efficiency in a joint tensile test.
Another embodiment of the method of producing flexible fabric bags, comprises the steps of coating a polypropylene fabric with 100% VERSIFY™ 3000, or other suitable propylene elastomer or plastomer with a melting point less than the melting point of the polypropylene fabric, or coating the fabrics with a combination VERSIFY™ 3000, or other suitable propylene elastomer or plastomer with a melting point below the melting point of the polypropylene fabric, and polyethylene, and joining the fabrics (not specifically just edges) using a combination of heat and minimal pressure in such a manner that only the coatings are welded together and not the fabrics, thus producing a joint that will have a strength greater than the original uncoated fabric.
In one or more embodiments of the present invention, all weight bearing points in the flexible bag are designed so that a welded or heat sealed joint will be stressed in the shear direction when the bag is being properly used.
In one or more embodiments of the present invention, if lifting loops are provided, the lifting loops are further protected against peel forces with an additional piece of protective piece of material applied over the top portion of the lift loop seam to protect against peel pressures.
Another embodiment of the present invention comprises a method of producing a flexible polypropylene fabric bag with heat fused seams comprising: providing fabric pieces, wherein each fabric piece has a coated side and an uncoated side; positioning fabric pieces so that a coated side of one fabric piece faces a coated side of another fabric piece; selecting an area of fabrics to be joined for forming one or more seams or joints; applying heat to the area to be joined that is less than the melting point of the fabrics, for forming one or more seams or joints.
In another embodiment of the method of the present invention, the seams or joints between pieces of fabric are formed one at time, to produce a flexible polypropylene fabric bulk bag.
In another embodiment of the method of the present invention, the seams or joints between fabric pieces are joined in a single step to produce the main body of the flexible polypropylene fabric bulk bag.
In another embodiment of the method of the present invention, the seams or joints of the flexible polypropylene fabric bulk bag retain at least about 85% of the fabric strength without using sewing machines.
In another embodiment of the method of the present invention, the seams or joints of the flexible polypropylene fabric bulk bag retain at least about 90% of the fabric strength.
In another embodiment of the method of the present invention, the seams or joints of the flexible polypropylene fabric bulk bag retain at least about 96% of the fabric strength.
In one or more embodiments of the method of the present invention, joints or seams retain at least about 100% of the fabric strength without using sewing machines.
In one or more embodiments of the method of the present invention, for each seam or joint, a joined coated portion of one fabric piece forms a half of one seam or joint, and a joined coated portion of another fabric piece comprises a second half of the same seam or joint.
Another embodiment of the present invention comprises a method of producing flexible fabric bags with heat fused seams in a single step, comprising:
a. providing 8 layers of flexible fabric, including: i. a top layer for a top panel, having a flat side; ii. a second layer for a body panel, having a flat side; iii. a third layer for a body panel, having a gusset side; iv. a fourth layer for a top panel, having a gusset side; v. a fifth layer for a top panel, having a gusset side; vi. a sixth layer for a body panel, having a gusset side; vii. a seventh layer for a body panel, having a flat side; viii. an eighth layer, for a top panel having a flat side; b. wherein the layers of fabric comprise a layer of coating; c. positioning the layers of flexible fabric so that all areas intended to be joined have coating facing coating and all areas intending not to be joined are uncoated fabrics facing uncoated fabrics; d. positioning the layers of fabric so that there is an overlap of the fabric layers; e. centering the overlapped portions of fabric under a seal bar; and f. applying low heat and low pressure to create heat fused or heat welded or heat sealed seams or joints.
In another embodiment of the method of the present invention, the method preferably comprises pulse heating.
In another embodiment of the method of the present invention, heat is preferably applied from top and bottom directions to the flexible layers of fabric.
In another embodiment of the method of the present invention, heat is preferably applied from one direction to the flexible layers of fabric.
Another embodiment of the present invention comprises a polypropylene container comprising heat fused seams, wherein the seams comprise a “T” shape, and wherein the right side of the “T” seam in a shear position enables protection of the left side in a peel position when force is applied in the right direction, and wherein the left side of the ‘T’ seam in a shear position enables protection of the right side in a peel position when force is applied in the direction of the left side.
Another embodiment of the present invention comprises a method of automated production for producing flexible fabric bags with heat fused seams comprising: a. providing layers of flexible fabric, including tubular flexible fabric portions, wherein some layers are gusseted and some layers are flat, and wherein the layers of flexible fabric comprise a layer of coating; b. positioning the layers of tubular flexible fabric so the gusseted layers comprise coating on the outside and the flat fabric layers comprise coating on the inside of their gussets; c. positioning the layers of fabric so that one layer overlaps an adjacent layer; and d. applying low heat and low pressure to the overlapped portions of the layers of fabric to create heat fused or sealed seams.
Another embodiment of the method of producing flexible fabric bags with heat fused seams comprises: a. providing fabric pieces, wherein each fabric piece has a coated side and an uncoated side; b. applying heat that is less than the melting point of the fabric pieces to be joined for joining fabric pieces to create one or more seams or joints wherein for each seam or joint, a coated side of one piece of fabric will form a half of the seam and will face a coated side of another piece of fabric for forming the other half of the seam.
In another embodiment of the present invention, the one or more joints have a joint strength equal to or greater than about 85% of the fabric.
In another embodiment of the present invention, the one or more joints have a joint strength equal to or greater than about 85% of the fabric without using sewing machines.
In another embodiment of the present invention, the overlapped portions of fabric are about 1½ (3.81 cm) inches and the overlapped portions of fabric are centered under about a 2 inch (5.08 cm) wide seal bar.
Another embodiment of the method of the present invention comprises joining polypropylene woven fabrics by the following steps:
In various embodiments, the fabrics are not being heated up past their melting points.
In various embodiments, the fabrics are only being heated to a point below the melting point of the woven fabric but high enough to melt the coating.
In various embodiments, by using such relatively low heat, the inventive process does not damage or reduce the strength of the fabric.
In various embodiments, low pressure is applied to clamp the fabrics together to complete the seal.
In various embodiments, the pressure applied is under about 7 psi (48 kilopascals).
In various embodiments, the pressure applied is about 2 to 7 psi (14 to 48 kilopascals).
In various embodiments, the pressure applied is about under 2 psi (14 kilopascals).
In various embodiments, by using low heat and low pressure, only the coating itself is being joined, leaving the fabric completely undamaged and unweakened.
In various embodiments, the strength of the coating adds to the overall joint strength, and the resulting joint strengths, allow one to lift higher weights with less material than can be done with the current, commonly used methods of sewing fabrics together.
In various embodiments, the fabrics are similar to polypropylene.
In various embodiments, the fabrics are woven of a plastic material other than polypropylene.
Another embodiment of the method of joining highly oriented polypropylene woven fabrics comprises the following steps:
a) coating the fabrics with a coating comprising VERSIFY™ and polyethylene resins, the coating having a melting point that is at least about 5 degrees lower than the melting point of the polypropylene fabrics to be joined together:
b) heating the coating to its lower melting point; and
c) joining the heated materials with sufficient pressure to allow the coating to remain in place and yet not allow the woven fabrics to make direct contact in order to achieve at least about 91% joint efficiency.
In various embodiments, the coating comprises about 50% to 90% of propylene-based plastomers, propylene-based elastomers, or mixtures thereof and about 10% to 50% polyethylene resins and additives, having a melting point that is at least about 5 degrees lower than the melting point of the polypropylene fabrics to be joined together.
In various embodiments, the coating comprises about 50% to 90% of VERSIFY™ 3000 and about 10% to 50% polyethylene resins, having a melting point that is at least about 5 degrees lower than the melting point of the polypropylene fabrics to be joined together.
In various embodiments, the coating comprises about 50% to 90% of a propylene copolymer and about 10% to 50% polyethylene resins.
In various embodiments, the coating has a melting point that is at least about 15% lower than the melting point of the polypropylene fabrics to be joined together.
Another embodiment of the method of joining highly oriented polypropylene woven fabrics comprises the following steps:
a) coating the fabrics with materials comprising about 70% VERSIFY™ and about 30% polyethylene resins, having a melting point that is at least about 5 degrees lower than the melting point of the polypropylene fabrics to be joined together:
b) heating the coating to its lower melting point; and
c) joining the heated materials with sufficient pressure to allow the coating to remain in place and yet not allow the woven fabrics to make direct contact in order to achieve at least about 91% joint efficiency.
As discussed herein, Flexible Intermediate Bulk Containers (FIBC) or bulk bags with heat fused joints in accordance with principles herein, have improved functionality, increased sustainability, and are revolutionizing the bulk bag industry. By innovating on the standard hand-sewn bag construction to an automated heat sealing process, this improved technology enables a cleaner and higher performance bag that impacts every part of the value chain.
An improved embodiment of the method and machinery of the present invention includes an intermediate stage heat sealing closed loop production line, including an automated FIBC manufacturing system that can have a continuous sequential closed loop flow of product.
One or more embodiments of an overall System can include:
a. first fully or almost fully automated heat sealed bag assembly line
b. sequential flow—lower labor and less product movement
An automated heat sealed bag assembly line can include:
1. Carrier Plate, including the following features and functions
a. precision guides for all parts of a bag
b. precision bag alignment—(e.g., to keep bags within about 1/16 inch (0.159 cm) tolerance).
c. can be used as a precision set-up tooling for the impulse heat sealing machines
d. single piece main plate is preferred to insure high degree of accuracy
e. clamps bag parts in position
f. preferably bag is never removed from carrier plate until completion through both impulse heat sealing machines.
2. Main Body Carrier Plate Assembly Table, including the following features and functions:
a. precision carrier guides for precision movement of the carrier plate from the carrier plate assembly table into impulse heat sealing machines.
3. Main BodyTop/Bottom/Spouts Impulse Heat Sealing Machine, including the following features and function:
a. all heat seal bars are preferably two axes self-adjusting for maintaining equal pressure during sealing process:
b. heat sealing elements are single piece—prior art industry is 3 pieces minimum:
c. fail safe temperature control preferably with at least dual sensors:
d. sensors are 1/32″ (0.079 cm) higher than insulation pad to ensure that the two sensors are seeing equal pressure as two parts of a three way triangle points of contact;
e. clamping system on seal bars for holding Teflon cover in place—industry uses tape
4. Loop/Diaper carrier Plate Assembly Table, including the following features and functions:
a. carrier plate once again ensures accurate placement of parts—loops and diaper;
b. precision carrier guides for precision movement of the carrier plate from the carrier plate assembly table into impulse heat sealing machines
5. Loop/Diaper Impulse Heat Sealing Machine, including the following features and functions:
a. same unique features as number 3; and
b. both loop seal bars are preferably three axes self-aligning for maintaining equal pressure during sealing process.
6. Bag Unload Carrier Plate Table, for unloading completed bag from carrier plate.
7. Return Conveyor, which can be commercial with Ameriglobe, LLC advanced electronics
In one or more preferred embodiments of the heat sealing closed loop production line system and method, non-sewn FIBC bags can be produced in about 2.5 to 5 minutes.
In preferred embodiments of the heat sealing closed loop production line system and method, heat welded FIBCs can be produced in about 2.5 to 5 minutes. In preferred embodiments of the heat sealing closed loop production line system and method, substantially flat fabric parts or pieces in (2-D) construction facilitates the automation process and precision (that is =/− about 1/16 inch (0.159 cm)) in the FIBC manufacturing.
In preferred embodiments of the heat sealing closed loop production line system and method, an FIBC bag is produced with no manufacturing equipment/tools making contact with an inside of the bag during manufacturing.
In preferred embodiments of the heat sealing closed loop production line system and method, an FIBC bag is produced with no manufacturing equipment/tools making contact with an inside surface of the bag during manufacturing.
In preferred embodiments of the heat sealing closed loop production line system and method, two and three axes impulse heat sealing heads are utilized which allow full self-alignment during the heat sealing process.
In various embodiments, single piece heating elements allow for lower costs and lower maintenance change-over time.
In preferred embodiments of the heat sealing closed loop production line system and method, at least dual fail-safe sensor controls over the set temperature points are utilized.
In preferred embodiments of the heat sealing closed loop production line system and method, a multiple purpose carrier tray system can be used for (a) parts assembly, (b) tooling set-up and (c) quality checks of parts during assembly.
In various embodiments, during the manufacturing process, the FIBC bag as it is being manufactured never leaves the carrier plate that it is attached to which insures a high degree of parts placement control, until a bag is completed.
In various embodiments, advantages of the heat sealing closed loop production line system and method include
In various embodiments of the bulk bag heat sealing closed loop production line system and method, a production flow system overview and sequence steps, includes the following:
1. Providing individual fabric parts for a bulk bag in substantially flat and folded or gusseted configuration on a main body cart. (The bag fabric parts on the main body cart can include one or more discharge spouts, body portions, fill spouts, tops, bottoms, and/or a document pouch. One or more bag fabric parts can be folded and gusseted and then pressed to a substantially flat condition in a 2-D configuration prior to placement on the cart.)
2. The individual parts of the bag can be assembled by an operator on a carrier plate, which can be placed on a main body assembly table for an initial bag to be made or as part of an assembly line and placed on the table after the previous cycle.
Preferably a carrier plate includes spout guides that provide an indication of how to line up the fill and discharge spouts on the carrier plate and with respect to the other bag pieces, and which allow for quality check of the placement of the spout bag pieces. Preferably a carrier plate also includes tooling location points for helping to align the carrier plate in the heat sealing machinery.
Preferably a carrier plate also includes one or more holding clamps for holding fabric pieces in place on the carrier plate. Preferably a carrier plate includes body guides that provide an indication for how to place and line up the body on the carrier plate and a quality check for the placement of the body. Preferably a carrier plate includes top/bottom guides that provide an indication for how to place and line up the top and bottom on the carrier plate and with respect to the other fabric pieces, and provides a quality check for placement of the top and bottom pieces.
Preferably carrier plate guides and quality check indicators are provided on the carrier plate based on desired dimensions for a bag to be heat sealed, and desired locations of bag joint overlap areas.
3. The assembled bag, while still clamped onto the carrier plate via one or more holding clamps can then be moved into position into a heat impulse sealing machine, e.g., a main body impulse sealer machine. Once the carrier plate is in position (which can be detected by a sensor), the cycle of the machine can be initiated at a control panel by an operator. A preferred embodiment of a heat sealing main bag body machine can include 4 top side heat sealing bars that can be pushed downward onto a top bag surface over 4 main bag joint locations and correspond to the location of 4 bottom side heat sealing bars that can be in contact with a bottom surface of the bag in 4 main joint locations. A fifth upper heat sealing bar can also be provided in a main body sealing machine for heat-sealing a document pouch. The 5 top side heat sealing bars of the machine are preferably pushed downward (preferably at 2 psi (13.8 kilopascal) to the mating 4 lower side heat sealing bars by pneumatic cylinders. The top 5 Heat Sealing Bars and lower 4 Heat Sealing Bars can heat seal bag joints at 5 connection areas, between the discharge spout and bottom, top and fill spout, top to the body, bottom to the body, and for a document pouch. Preferably, pneumatic cylinders remain in an extended position during a temperature ramp-up period, a temperature bake time and a cool-down time. At the completion of the temperature times, the pneumatic cylinders can retract and are ready for the next cycle.
4. The individual bag fabric parts for the lift loop assemblies and the diaper/bottom cover can be located on a loop/diaper cart.
5. The heat sealed assembled bag, while still clamped onto the carrier plate, can then be moved from the first heat sealer machine, e.g., a main body impulse sealer machine, onto a loop/diaper assembly table. The loop assemblies and diaper can be placed in their proper position on the heat sealed assembled bag while on the carrier plate and can be clamped with the holding clamps.
6. The heat sealed assembled bag, while still clamped onto the carrier plate is then moved into position into a second heat sealer machine, e.g., a loop/diaper impulse sealer machine. Once the carrier plate is in position in the second heat sealer machine (which can be detected by a sensor), the cycle of the machine can be initiated at a control panel (e.g., a second control panel) by an operator. While in the second heat sealer machine, 3 top side heat sealing bars can be pushed downward (e.g., preferably at 30 psi) to mating 3 lower side heat sealing bars by pneumatic cylinders. The top 3 heat sealing bars and lower 3 heat sealing bars can heat seal at the 3 connection areas for the lift loop assemblies and bottom cover or diaper.
Preferably the second heat sealing machine can couple 4 lift loop assemblies to the bag and the bottom cover. One pair of upper and lower heat sealing bars can be positioned in the machine above and below joint locations for two lift loop assemblies positioned on one side of the folded bag, a second pair of upper and lower heat sealing bars can be positioned above and below joint locations for another two lift loop assemblies positioned on the other side of the folded bag, and a third pair of upper and lower heat sealing bars can be positioned above and below a joint area for the bottom cover. The carrier plate can include guides and quality check indicators for positioning the respective lift loop assemblies on the bag and the bottom cover on the bag. The carrier plate can also include indicators for lining up the bag in the second heat sealing machine in line with the respective heat sealing elements.
7. The assembled bag, while still clamped onto the carrier plate can then be moved onto a finished bag unload table where the bag is unclamped from the carrier plate and moved to a finished bag area. The carrier plate can then be moved onto a conveyor system that will automatically return the carrier plate to the starting position. e.g. near the main body assembly table or to the main body assembly table.
In various embodiments of the bulk bag heat sealing closed loop production line system and method, sub-assemblies and support equipment can include:
1. A seal bar that can have a typical 2 inch (5.08 cm) wide seal bar construction, and preferably can be water cooled to decrease the cool-down time. Preferably a seal bar has at least twin fail-safe sensor controls to monitor and regulate tight temperature control (e.g., to about +/−1 degree)
2. An upper seal bar preferably has a two axis pivot yoke to insure uniform pressure during the heat sealing process when pressed against its mating lower seal bar by two pneumatic air cylinders, for example.
3. A Teflon seal bar heating element cover preferably is held in place by clamp bars.
4. The heating element preferably is of single piece construction and is held in place by a pivoting clamping assembly. The heating element can be stretched to its proper tension by two springs.
5. The heating element preferably is insulated from the seal bar by an insulating material; e.g., a rubber insulation material.
In various embodiments of the bulk bag heat sealing closed loop production line system and method, a loop seal bar construction can include the following:
1. a seal bar that can be water cooled to decrease the cool-down time and preferably has twin fail-safe sensor controls to monitor and regulate tight temperature control (e.g., within about +/−1 degree F. (−17.2 degrees Celsius));
2. the upper seal bar preferably has a three axis pivot yoke to insure uniform pressure during the heat sealing process when pressed against its mating lower seal bar by two pneumatic air cylinders, for example;
3. a Teflon seal bar heating element cover preferably is held in place by clamp bars;
4. preferably the heating element is a single piece construction and is held in place by a pivoting clamping assembly, and wherein the heating element can be stretched to its proper tension by two springs;
5. preferably the heating element is insulated from the seal bar by a rubber insulation material.
In various embodiments of a carrier plate of the bulk bag heat sealing closed loop production line system and method, preferably:
1. The carrier plate is precision milled within =/− about 0.01 inch (0.0254 cm); and
2. The carrier plate serves as a (a) precision parts assembly platform, (b) tooling plate for machine set-up and (c) a material quality check during assembly.
In various embodiments of a main body cart of the heat sealing closed loop production line system and method, preferably:
1. the main body cart is preferably designed to exacting dimensions to hold a full day's production of main body parts; e.g. bulk bag fabric pieces in repeatable and accurate positioning; and
2. the main body cart is designed to be unloaded from either side.
In various embodiments of a loop/diaper body cart of the bulk bag heat sealing closed loop production line system and method, preferably:
1. The loop/diaper body cart is designed to exacting dimensions to hold a full day's production of Main Body Parts in repeatable accurate positioning; and
2. The loop/diaper body cart is designed to be unloaded from either side.
In various embodiments using automation, producing a bulk bag or FIBC in 2D (two-dimensional) form is important for automation.
The gusseted and folded configuration of the fabric pieces that are substantially flattened prior to entering the heating sealing machinery enables a bag joint to be formed around a circumference of the bulk bag at joint locations all while it is in the flattened and folded 2D configuration. The fabric gusseted and folded pieces can include fill spout, top, body, bottom, discharge spout, lift loop assemblies and bottom cover. In the prior art methods of sewing the bags, the bags are sewn in 3D or three dimensional configuration, wherein bags need to be opened up during the sewing process.
In various embodiments, dimensions of a fabric part carrier table can vary based on the dimensions of the fabric parts it will hold. Dimensions of the fabric parts can be selected based on desired bag dimensions.
In various embodiments, use of a combination of tubular fabric (e.g., for a body portion and fill and discharge tubes) and flat sheets of fabric (e.g., for top and bottom portions) allows for a minimal total fabric usage to produce the bulk bag. In the prior art for example, more fabric than is needed is used in forming sewn seams for the bag, for example.
Through experimentation and testing with automation for production of bulk bags, gusseting is the only known way to match differing fabrics for automation. All of the above results in minimal square inches (centimeters) of material being used while still being able to obtain at or around the same pounds per square inch (kilograms per square centimeter) as with sewn seams and heavier fabric, for example.
In the prior art, liners have been cut out of gusseted material as a single piece liner, but this results in a lot of wasted fabric. In embodiments of the present invention with a five fabric pieces for assembling a bag, gusseting of the pieces, allows the different sized pieces to fit together. Use of different fabric portions for the bag assembly also allows for potential selection of a different fabric for each piece, e.g., fabrics of different thickness, densities, weights and/or strengths. For example, a bottom portion could be made of thicker fabric than what is used for a top portion. This may be desirable to make the bottom as strong as possible, but allowing for savings in cost for other bag fabric pieces.
In various embodiments, the bag fabric portions include a top and bottom portion both of which are constructed from flat fabric pieces that are then folded or gusseted into a desired fold configuration for assembly with the other bag pieces. In various embodiments a discharge tube and fill spout and body are formed from tubular fabric pieces that are then folded or gusseted into a desired fold configuration for assembly with the other bag pieces. In various embodiments an opening in a bottom portion is substantially square in shape and receives a tubular portion of a discharge spout.
In various embodiments the gusseted configuration of the bag portions and the heat sealing method enable use of the least amount of fabric in the bag construction as possible, without waste from overlapping used in sewn seams for example, or in cutting out a single piece bag from an overall fabric piece with wasted fabric portions. In sewing, generally you have about a 1 to 1.5 inch (2.54 to 3.81 cm) fold on each side for sewing.
In preferred embodiments of automation for bulk bags, flat sheets of fabric and tubular pieces of fabric are gusseted and then pressed or substantially flattened. Portions of one piece of fabric can be fit within a portion of another piece of fabric to form an overlapped and desired joint area. When the overlapped areas are heat sealed, the joint is formed around the entire circumference of the fabric pieces, connecting the fabric pieces.
In various embodiments, the strength of bonds formed via heat sealing versus sewing strength allows reduction on total weight of fabric in the heat sealed bags, versus sewn bags.
In various embodiments, a lift loop assembly includes a lift loop attached to a lift loop panel, and wherein the panel is the portion that forms a heat sealed joint with the bag fabric. A lift loop panel can be substantially rectangular and positioned either laterally or longitudinally on the bag. A lift loop panel can also be substantially square or other desired shape.
In various embodiments of a bulk bag including heat sealed joints, fabric tape can be included on an edge of a lift loop panel to increase the bond strength of the heat sealed panel, by delaying the peel point. Preferably tape is added along a vertical or longitudinal edge of the lift loop panel.
The tape along a lift loop panel edge can be fabric tape including an adhesive backing and can be coupled to the bag via the adhesive. In some embodiments fabric tape can be included along each lift loop edge. In some embodiments tape is only included along an inner longitudinal edge of a lift loop panel 59 of the bulk bag. In some embodiments tape is only included along a vertical inner edge of lift loop panel 59.
In various embodiments, lift loop panel can be any desired shape.
In various embodiments a lift loop panel can be rectangular in shape with the longer sides of the rectangle positioned substantially horizontally on the bulk bag. In such embodiments tape along the edges of a lift loop panel are not necessary for delaying the peel.
The tape at the edge of the lift loop panel can be beneficial to help prevent curling of the fabric that can occur during the heat sealing process when just a lift loop panel or patch without the tape is heat sealed to the bag.
In various embodiments, the method includes fully bonding every part of a joint area to an outside edge of the respective pieces being joined, e.g., so that there is no graspable portion, restricts peeling. Fully bonding to the outside edge discourages manual attempts to damage the bond by picking at the important edge and causing early release of the bond. This can be accomplished by having the heat seal bar extend beyond the location of a desired joint edge.
In various embodiments, e.g., if a bag body includes a bonding coating that includes propylene elastomers and plastomers, a buffer is preferably placed between portions of fabric wherein a bonding coating is in contact with another bonding coating given the gusseting of the bag pieces, and for which it is not desired to create a bond. For example, when heat sealing the diaper or bottom cover to the bag, a buffer can be placed during the bonding process whenever and wherever a bonding coating meets a bonding coating. This can require a buffer in the diaper cover area. A buffer for example can be wax paper. A buffer, e.g., wax paper, can also be used when heat sealing the lift loop assemblies to prevent heat sealing body gussets together, for example, if the body exterior includes a bonding coating, e.g., a propylene based elastomer or plastomer coating.
Preferably a bottom cover or diaper is cut at an angle so that a pull tab is formed which can easily be pulled and removed by a user when ready to discharge bag contents.
In various embodiments, fill spout and discharge tube fabric ties can be attached to a fill spout or discharge tube via adhesive tape, e.g., polypropylene or polyethylene fabric tape with an adhesive thereon.
In various embodiments, a tint can be added to a coating on bag pieces, e.g., a bonding coating or the standard polypropylene fabric coating, so that after the coating is applied to the fabric it is easily identified as the particular type of coating. For example, a green tint or other desired color, can be added to a bonding coating. In preferred embodiments, the bonding coating with tint can be applied at 2 to 4 mils (0.05 to 0.10 millimeters). A shade guide can be provided as a quality check wherein the tint at 2 mils (0.05 millimeters), for example, will be a certain shade. If tint is darker or lighter than what it should be at 2 mils (0.05 millimeters), this can be an indication that the bonding coating was not applied to designated thickness and can provide another quality check function for the bag.
Tinting the bonding coating on the fabric can also help make sure the special bonding coating is in the proper position.
Tinting the bonding coating on the fabric can also help to identify the proper thickness of the coating.
In various embodiments a standard fabric polypropylene coating can be tinted instead of the bonding coating, or the standard fabric polypropylene coating can be tinted a different color than the bonding coating. A shade guide can also be used to measure if the standard fabric polypropylene coating is applied at the right thickness.
In various embodiments, lift loops are made of all fabric, which further eliminates sewing from the bag manufacturing process.
In various embodiments, lift loops are made of all fabric, e.g., of the same highly oriented polypropylene fabric used for the bag fabric pieces for top, bottom, fill and discharge spout and body portions.
In various embodiments, tape can be used to secure the spout ties versus sewing. This again, eliminates sewing thread and machines from the production line and any attendant loose threads.
In various embodiments, tape, e.g., fabric tape with an adhesive backing, can be used to couple a spout tie to a discharge tube or fill spout.
In various embodiments, an oversized top can be accomplished by repositioning the lift loops lower on the bag. This can easily be done with the heat sealing method, wherein the lift loop assembly is positioned on the bag and attached to the bag at a desired lower location on the bag body, e.g., about 4 to 6 inches (10.2 to 15.2 cm) below an upper edge of a bag body portion, and then the lift loop assembly can be heat sealed to the bag body at the selected location using a sealing bar. With sewing methods, it can be difficult to sew the loops lower down on a bag as sewing machines typically are not constructed to easily do this. Costs include more manpower to reposition the loops for this function. With one or more heat sealing embodiments as described herein, it is not easy to incorporate an enlarged top to be connected to a body of typical dimensions, as dimensions of the oversized type and gusseting formation may not properly align with the typical size body.
In various embodiments a bonding coating, e.g., including propylene based elastomers and plastomers needs to be present in all joints, at least on one fabric piece in the overlapped area in which a joint will be formed.
In one or more preferred embodiments, all tubular materials or fabric pieces are coated with a bonding coating, and all other fabric pieces or materials are coating using an industry standard coating. But everything can be also be reversed in other embodiments, so long as at the point of bonding either two coated surfaces with a bonding coating faces each other or one coated surface with a bonding coating and one coated surface with an industry standard coating are being joined.
In one or more preferred embodiments, a discharge tube, body and fill spout are coated with a bonding coating, and all other fabric pieces or materials (e.g., a top, bottom, lift loop panel, diaper cover or document pouch) are coating using an industry standard coating.
In one or more preferred embodiments, a discharge tube, body and fill
spout are coated with a standard industry coating, and all other fabric pieces or materials (e.g., a top, bottom, lift loop panel, diaper cover or document pouch) are coating using bonding coating. In various embodiments a bulk bag can include one heat sealed joint between a fabric piece with a bonding coating and a fabric piece with a standard industry coating.
Experimentation has shown that a standard polypropylene fabric coating that comprises a majority of polypropylene and some polyethylene does not work as a bonding coating to form a bond that can work as a bag joint when a standard polypropylene fabric coating on one piece of fabric is bonded with a standard polypropylene fabric coating on another piece of fabric.
In embodiments where a propylene based plastomers or elastomers coating is on one piece of fabric and bonded with a standard polypropylene fabric coating on another piece of fabric, a bulk bag heat sealed joint is being formed with a bonding coating on only one piece of fabric that is being joined to another piece of fabric.
In various embodiments, a bulk bag can include one heat sealed joint between a fabric piece with a bonding coating and another fabric piece with a bonding coating.
In various embodiments a bulk bag can include more than one heat sealed joint between a fabric piece with a bonding coating and a fabric piece with a standard industry coating.
In various embodiments a bulk bag can include more than one heat sealed joint between a fabric piece with a bonding coating and another fabric piece with a bonding coating.
In the practice of coating tubular pieces of fabric with a coating, a coating is applied to the fabric while the tube is substantially flattened, and in practice the applied bonding coating does not typically cover the folded edge of the tubular piece. In preferred various embodiments of the present invention, tubular materials are coated with a bonding coating in a manner that brings the coating at least to the folded edge or just over the folded edge for strength in the folded edge area.
Typically in the prior art, when applying a coating to fabric, e.g., to tubular fabric pieces, an operator will apply clear tape to the folded edge and then coat onto the tape. This in practice can leave an uncoated area of up to about 1.5 inches (3.81 centimeters). If a bonding coating is applied to the fabric in this manner with tape applied to the folded edge, the result is that the fabric piece can have at or about a 1.5 inch (3.81 centimeters) or more area that does not include the bonding coating. This means that a heat-sealed joint will have a weak area, e.g., in an area where a bond between coatings of the fabric pieces is not formed.
In various embodiments of the method of the present invention, tubular fabric pieces are coated with a bonding coating in a manner that brings the coating at least to the folded edge or just over the folded edge for added strength in the folded edge area when applied to the tubular fabric in flattened configuration. In various embodiments, the coating will be applied at or around ⅛ inches (0.32 cm) before an edge of the tubular fabric, or at or around ⅜ inches (0.95 cm) past the edge of the coated fabric. In various embodiments, the coating will be applied from an edge, and at least not more than ⅛ inches (0.32 cm) before an edge, of the tubular fabric, or at least ⅜ inches (0.95 cm) past the edge of the coated fabric. Although it is preferred to have coating on an entire exterior or interior surface of a tubular fabric piece, in practice if this is not practical, a preferred method has coating up to the edge or no more past the edge than ½ inch (1.27 cm) beyond the edge for greater strength.
In various embodiments, a standard polypropylene fabric coating can also be applied to fabric pieces in a same or similar manner, wherein, tubular fabric pieces are coated with a standard polypropylene fabric coating in a manner that brings the coating at least to the folded edge or just over the folded edge for added strength in the folded edge area when applied to the tubular fabric in flattened configuration. In various embodiments, the coating will be applied at or around ⅛ inches (0.32 cm) before an edge of the tubular fabric, or at or around ⅜ inches (0.95 cm) past the edge of the coated fabric. In various embodiments, the coating will be applied from the edge, and preferably not more than ⅛ inches (0.32 cm) before an edge of the tubular fabric, or at least ⅜ inches (0.95 cm) past the edge of the coated fabric.
In one or more embodiments, a bag body and/or bottom portions can be folded or gusseted so that portions of the fabric that do not include a coating (e.g., which may occur at folded edges during application of a coating as described above), will be positioned wherein a bottom cover or diaper portion will cover those non-coated areas, or a portion of the bag fabric that may still have the tape applied during the coating application.
In practice, a coated tubular piece of fabric to be used to form a bag fill spout, body portion, or discharge tube, may be received in a substantially flattened configuration with two folded edges that do not have coating covering the folded edges. During the folding or gusseting stage of the fabric portions, a tubular piece of fabric can be newly folded wherein the uncoated folded edges are moved to a substantially central position on the tubular piece of fabric, and then with gusseting and pressing being done as described further herein with respective to
In various embodiments, the bottom discharge structure is configured to strengthen the discharge structure and strengthen a zero point area at the discharge tube and bottom panel joint.
In construction of a heat fused bag wherein a bottom portion opening is constructed with four slits, a zero point area can occur at about the 90 degree angle point, wherein two pieces are at about 90 degrees respective to each other, going from the horizontal to the vertical, at bottom portion slit areas, which are weak areas in a heat sealed bag. Taping configurations as described herein can overcome the weak area at the zero point. In other embodiments, a discharge tube in gusseted form can be positioned through the bottom opening and sealed to the bottom flaps wherein the slit between bottom flaps is not located at a corner of the gusseted discharge tube in folded and flattened configuration. For example, the discharge tube and bottom flaps can be fused together wherein the bottom slits are located at or about centrally between the corners of the discharge tube in folded and gusseted form. When sealed in this manner, the weak areas do not result in a blowout point for the bag when heavier contents are included therein.
In various embodiments, the slits between the bottom opening flaps are preferred because the slits enable some expansion of the opening going from a smaller square to a larger circular shape.
In various embodiments, the automation system and process of the present invention can be used to produce a two loop design bag that is popular in Europe. In various embodiments, substantially square spouts are utilized and are important to the gusseting designs of this bag. Square spouts allow for heavier weight to be successfully held in a bag, than in the other embodiments, e.g., without a square spout.
In various embodiments, heat fused bulk bags with heat sealed joints can be priced competitively relative to conventional sewn bulk bags based on the value they generate due to their enhanced performance and sustainability. Example—Price for imported bag with liner is $12.09 USD and price of a similar heat sealed bag can be $12.09 USD.
A bulk bag with heat sealed joints in accordance with one or more principles herein is a novel technology that enhances bag performance, sustainability, and cleanliness via a scalable manufacturing process based on a heat sealing construction. As previously discussed, woven polypropylene fabrics have been the fabric of choice in the bulk bag industry, given the strength, cost and flexibility of the fabrics, but more importantly, due to its nearly perfect chemical inertness. The polypropylene fabrics are highly oriented through a heating and stretching process to achieve maximum strength while maintaining the needed flexibility of fabrics to fit the needs of the marketplace. As discussed, the challenge has been, “With the chemical inertness, how does any process achieve a strong enough seal without damaging the inherent and important properties?” Prior art methods and ways to join polypropylene fabrics with sealed joints has worked with small bags of up to 100 pounds (45 kilograms). But to meet the FIBC industry's safety standards, for some applications the bags must be able to hold suspended weights of up to 16,500 pounds (7,484 kilograms), to meet the 5 to safety ratio. Up until the heat sealed bags and method and technology as described herein was created, no accepted or useful method has been found for a bulk bag that can carry such weight safely.
The Flexible Intermediate Bulk Container (FIBC)/bulk bag industry is now over 40 years old. Currently, the FIBC market is estimated to sell 200 to 300 million FIBCs a year with an average price of $12.00) USD. It is a $2.5 billion market that has been growing steadily at 7% per year for more than two decades and shows no signs of slowing down its growth. The very first bulk bags were constructed by combining various configurations of woven polypropylene fabrics and woven webbing by sewing them together to get the needed strength. Today, sewing remains nearly the exclusive method for connecting the materials of construction when making bulk bags. The determination of which fabrics to use and which sewing patterns and which threads to use to combine these parts to create the most economical bulk bag container are well known and have been studied in great detail.
Heat welding has been tried and largely rejected because to heat weld as in the prior art, one must reach the melting point of the polypropylene fabrics to bond them together. However, the polypropylene fabrics are highly oriented and bringing them up to this temperature level results in a fabric tensile strength loss of approximately 50%.
The basic issue has always been that bulk bags must safely carry tremendous weights, for example in some cases up to 3,300 (1,497 kilograms) or 4,400 pounds (1,996 kilograms). Many prior efforts have shown that joints can be achieved but nothing in the prior art has shown itself to be able to carry these weights with the required 5 to 1 lifting safety in the resulting containers. Therefore, after 40 years of production, bulk bags are still manufactured largely through the original methods of sewing woven polypropylene fabrics together to form the bag and its lifting components.
The FIBC/bulk bag heat sealing technology in accordance with principles herein is a technology that utilizes a novel and automated thermal bonding process of highly oriented, woven polypropylene coated fabrics together through a combination of a uniquely formulated extrusion coating polyolefin blend, a specially designed bulk bag that keeps every seam in its strongest position for shear strength, and a specially designed and highly computer controlled heating system such that the thermally bonded (heat sealed) seam does not damage the strength of the chemically inert, heat sensitive polypropylene fabric and is able to retain greater than 95% of the original tensile strength of the fabric. This is a significant improvement over the strength of a sewn seam.
It is important to understand that in the present invention, the bag is not carrying the tremendous weights based on the strength of heated polypropylene fabrics. The strength of the bag and its lifting capacity is in the bond only that is formed between bag fabric pieces.
In various embodiments, the actual polypropylene fabrics are purposely separated by the bonding coating and only the coatings (e.g., a bonding coating and bonding coating or a bonding coating and standard laminate polypropylene fabric coating) are bonded together. A preferred bonding coating used has a lower melting point than the polypropylene fabrics. So while the coating is being heated up to its melting point to make the bond strong, the polypropylene fabrics do NOT reach their melting point and therefore keeps all of its original strength.
To accomplish this, the equipment that can be utilized in the automated heat sealing process has to be carefully designed to reach target temperatures below the polypropylene melting temperatures and to hold the temperatures long enough for the bonding coating to fully reach the target temperature without varying too high and reaching the melting point of polypropylene fabric.
Preferably the equipment, e.g., the heat sealing machinery, can hold the temperature within about a 5 degree range of the target temperature to help make sure that the resulting bond is strong and the fabric stays strong.
Preferably the bonding coating not only has the ability to bond with itself, but also can bond to the polypropylene fabric with enough strength that neither the bonding of the bonding coating to itself, nor the bonding of the bonding coating to the fabric piece will break under the pressure of the contents of the bag.
While many FIBCs are coated prior to sewing, the industry standard coatings are unable to bond to themselves with a bond strength of anything greater than about 25% of the material's own tensile strength. However, in the present invention, a standard industry coating can effectively be used to form heat sealed joint and bond when bonding the industry polypropylene fabric standard coating to a propylene based plastomers or elastomers coating.
When a standard polypropylene fabric coating on a first piece of polypropylene fabric is heat welded to a bonding coating (e.g., a propylene based plastomer or elastomer coating) on a second piece of polypropylene fabric, the bond between the standard coating and bonding coating, the bond between the bonding coating and second polypropylene fabric piece, and the bond between the standard coating and first polypropylene fabric piece will not break under the weight of contents in a bulk bag, e.g., up to 5,000 pounds (2,268 kilograms) or more of material contents in the bag.
Next a concern to deal with was the amount of labor used to produce a single FIBC. In the simplest design of a prior art FIBC, there can be about 428 inches (10.8 meters) of sewn seams alone. A sewing machine can only sew each seam individually and then it must also travel along every inch (2.5 cm) of every seam. Essentially, the FIBC is sewn in its final form or simply put in its 3 dimensional condition. This requires the machine operator to become very skilled at manipulating each inch (2.5 cm) of every seam of the bag in a proper condition under the sewing machine's needle. It takes an average of 3 months for any new operator to develop enough skill to make a single design of a bulk bag.
In the present invention, preferably the parts of the bag are gusseted into squares so that each piece nestles perfectly within its neighboring piece such that there is about a two inch (5.08 cm) wide sealing or overlapped joint area. The specialized equipment of the present invention assures the operator that all pieces are perfectly aligned by use of a frame, e.g., a carrier frame. Once this frame is filled, there are four seam or overlapped areas, each consisting of 8 individual layers of materials, the frame is placed in the specialized equipment, a start button is pushed and five sealing heads come down on the parts to seal the overlapped areas. The computerized controls can bring each individual sealing bar to the proper temperature and based on the thickness of the fabrics under each sealing head, can hold the temperature for a specified amount of time so that the entire thickness of the 8 layers will reach the perfect or target temperature, or temperature within a target range, for the maximum strength of the bond, for each particular seam or joint formed.
At this point a computer controlled cooling system can cool each bond to a second specified temperature which makes the bond permanent. As each sealing head completes its full cycle, the sealing head is retracted. When all four sealing heads reach the end of their individual cycle, the resulting bonds have turned all of the 8 layers mentioned above into four pairs of completed seams. Only the correct pairs of fabrics have been properly paired and no incorrect pairs of fabric have been seamed together. At this point, all 428 inches (10.9 m) of seams throughout the entire bag have been made in a single production step in a 2 Dimensional manner.
As mentioned 5 sealing heads can be included on a first stage machine. Four of the sealing heads can seal for bag containment area bonds, and a fifth sealing head can attach a document pouch to the bag. This step can be included without any extra labor. Alternatively, a first stage machine can include less than five sealing heads, e.g., 1, 2, 3, or 4, to form a desired number of joints 1, 2, 3, or 4 in a single step. The heat sealing machinery can include upper, or lower, or both upper and lower sealing heads to seal a joint area.
Once the FIBC has been through this step, which can be completed in about just 2.5 minutes, the bag can go through a second step to add lifting loops and/or a cover to the bottom to keep the discharge spout relatively clean of debris. This step can also take just about 2.5 minutes.
Lastly the bag can be folded, compressed and packaged on a shipping pallet. Then the bag is ready to be shipped to the end user who will fill the bags with product.
Because prior art sewn bulk bags are constructed with hand-sewn seams, which require a large amount of labor the majority of bags are being sourced out of Southeast Asian or other low cost labor markets. Because bags are manufactured in such a geographical position, most manufacturers around the world have an average delivery time from order to receipt of over 90 days. Along with these supply chain dynamics come issues in bag performance, contamination, and manufacturing defects. In this regard, the heat sealed bag and method of the present invention represents a significant step-change in bulk bag performance and manufacturing.
Advantages of the heat sealed bulk bag design and automated sealing process of the present invention are numerous.
As the new bag manufacturing uses heat-sealed seams in accordance with principles herein, this construction method can reduce production labor needs by around 70%.
The heat sealing solution as described in one or more embodiments herein does not have any needle holes and is nearly air tight, which results in the most sift proof bag in the market. Loss of bag contents by sifting through the sewing holes is one of the biggest issues in the FIBC industry, and huge efforts have been made to try to create sift-proof seams.
Additionally, with hand-sewn FIBC bulk bags, there is a minimum of 14 starts and stops with the sewing machine. Each sewn seam has two individual threads. Each time the machine stops and starts in a new seam, there are 4 thread end cut that need to be controlled. This is a minimum of about 56 opportunities for loose threads to be left inside the sewn bag. A single loose thread left within the bag can be cause for the entire contents of the bag to be labeled unusable. This often results in the rejection of an average of 2,204 pounds (999.7 kilograms) of good product that is lost to the supplier.
Faced with such losses of product, manufacturers who use FIBCs, often have polyethylene liners installed to keep the bag contents clean and secure.
Another issue resolved by one or more embodiments of the present invention is the prevention of sifting of product through the stitching holes all along every seam that the sewing method always produces. If the product contained within the bag is a hard to contain product such as carbon black, both of which can easily sift through the needle holes then a liner is needed in this situation as well. However, with the heat sealed FIBC bulk bag, the need for a bag liner is eliminated entirely. By eliminating this liner, and also eliminating the needle holes and thread and reliance on human sewing labor, the heat sealed bulk bag represents the cleanest and most sustainable known bulk bag.
Another concern in the prior art bags and method was the possibility of mishandling the FIBC in a manner that causes breakage. The most common catastrophic manner of failure is from picking up a bag that has fallen over in an incorrect manner. Sometimes forklift operators try to pick up a fallen bag that is lying on its side by lifting it with a single loop. This often causes the entire side of the bag so split open exposing the contents to the area around it. This causes the loss of the product due to potential contamination. Also, if the product was hazardous, this can cause a Hazmat event. This failure is inherent to the design of the bags. The prior art lift loops are sewn directly to the bag's containment wall itself. So, a lift loop failure naturally becomes a bag failure.
In embodiments of the present invention, a lift loop patch is heat sealed to bag. If the lift loop patch bond breaks, the lift loop patch will peel away from the bag fabric. but the bag fabric will not itself tear and bag contents will remain within the bag.
A bulk bag with heat fused joints of the present invention generally operates in the same fashion as currently sewn FIBCs so there will not be a learning curve for the end users nor the bag fillers.
Some features of a heat sealed bag design of the present invention are enabled by the heat sealing system.
In a prior art sewn bag, the discharge spout is often protected by a circular drawstring cover on the bottom of the bag. In order to access the discharge spout, this cover needs to be opened. This drawstring has the entire weight of the product within the bag against the knot that is holding the cover closed. Very often, the weight on this knot makes it very difficult to open. The operator is often found standing under the bag yanking on this knot. This is unsafe for the operator to do, but the operator's only other option is to bring out a knife to cut the tie cord and that is often not allowed in food grade factories. One or more embodiments of a heat sealed bag of the present invention eliminate this knot in favor of a piece of fabric covering the discharge tube and sealed to the outer edge of the bag in a manner that is easy to peel off the bag. With this improvement, the operator never has to reach or stand under the bag to undo the discharge spout cover.
Further, without a liner, the heat sealed FIBC can go directly to recycling versus having to separate a polyethylene liner from a polypropylene bag as is required in the prior art.
The production of a heat sealed bag in various embodiments of the present invention can also be enhanced by computerized controls. An operator in some cases can require a single day or less of training on the method of production of heat sealed bags.
To enable the heat sealed bulk bag construction, significant advances on the automation of bulk bag manufacturing, defect elimination, and more strict specifications have been made through testing. In the production of a heat sealed FIBC bulk bag, preferably all joints are made with a bonding coating heat sealing system that includes a bonding coating that is a propylene plastomer and elastomer, (e.g., VERSIFY™ 3000) on at least one piece of fabric to be joined. Also, significant advances have been made in the bag tolerance specifications by eliminating the human error in sewing, which can vary by 1″ (2.54 cm) or more. Due to the use of high accuracy cutting and sealing machines in the production stage, these bags can be accurate to within about ¼ inch or ⅛ inch (0.64 cm or 0.32 cm) in every aspect. As such, the heat sealed FIBC bulk bags stand straighter, which results in less prone to tilting and increases user safety. This increase in precision not only improves safety but also increases ease of use in automated filling and emptying of contents.
Importantly, advances in heat sealed bag construction of the present invention enable the production to be local to the consumer, instead of all being sourced from a few select countries. This has an impact on lead times, which are, through the embodiments of the present invention, now can be only 30 days as opposed to 100 days for sewn bags from SE Asia. As a result, stock inventories can be greatly reduced. This saves time and money on logistics and supply chain costs for the entire industry.
In various embodiments, a heat sealed bag can be built in two dimensional (2D).
In various embodiments a heat sealed bag is made in a gusseted, pressed, and substantially flat condition. Folding it for packing and shipping will be much easier and possibly automatable.
In the prior art every FIBC bag is currently handmade and has many inconsistencies. At AmeriGlobe, LLC a standard tolerance for sewn bulk bag height is about 1 inch (2.54 cm). For spout diameters it is about one half (½) inch (1.27 cm). Fabric cuts have a tolerance of about one half (½) inch (1.27 cm). The sewing process often gathers one side of each seam a little more than the other side. This can cause wrinkling and height variations. It also creates undependable seam strength variances as one side of the seam can be literally longer than the other side. If the sewing machine skips a stitch, the seam itself opens up under product pressure and creates losses. Sewing lines are not perfectly straight and vertical. This also causes uneven pressures along the seams and causes early seam breakage at the narrowest points. A heat sealed bag of the present invention, however, can be operated on the basis of zero defects. Machines will preferably have only about ¼ inch (0.64 cm) tolerances.
Additionally, cleanliness concerns include the machine oils and human bacteria left behind by the sewing process. These cannot be avoided because the machine must go inside the bag and a human must operate it in the prior art. In embodiments of heat seal machinery of the present invention, a multi-use table can be used that can make straight welds, e.g., transversely extending welds, for attaching the 5 main pieces of the bag together, and a large patch welder for attaching lift loops.
In various embodiments, a bulk bag of the present invention can be made with zero human or machine touch on the inside of a bag.
In various embodiments, a method of construction of heat sealed bags uses less materials than prior art bag construction, e.g., prior art sewn bag construction.
In various embodiments, a first major step in the production line is that the top spout, the top sheet, the body of the bag, the bottom sheet and the bottom spout can all be fused together in a single production step that can take about 20 to 25 seconds of machine time to accomplish.
In various embodiments of the method, and of the heat sealed bag, an operator is able to control the sealing surfaces to allow sealing 8 layers in a single stroke into 4 sealed pairs of fabric layers. This single step produces a heat sealed bag.
In various embodiments, a complete bulk bag can be formed in a single step in a single machine with 4 heat sealing bars, or 4 pairs of upper and lower heat sealing bars, to seal 4 bag joints simultaneously.
In various embodiments, a complete bulk bag can be formed in a single step in a single machine with 2 heat sealing bars, or 2 pairs of upper and lower heat sealing bars, to seal 2 bag joints simultaneously
In various embodiments, a complete bulk bag can be formed in a single step in a single machine with 1 heat sealing bar, or 1 pair of upper and lower heat sealing bars, to seal 1 bag joint.
In embodiments of a bulk bag without a fill spout or without a discharge tube, a polypropylene bag can be fabricated in a machine that includes two sealing bars or two pairs of upper and lower sealing bars to form a bag joint between the bag body portion and the top and bottom portions.
In some embodiments, a single heat sealing bar or a single pair of heat sealing bars can be utilized to form a bag with a bag body portion and a bottom.
In some embodiments, two sealing bars or two pairs of upper and lower sealing bars can be used to form a bag with a joint connecting a body portion and a bottom, and a joint connecting a discharge tube and the bottom.
In some embodiments, three sealing bars, or three pairs of upper and lower sealing bars can be used to form a joint between a top and a body portion, a bottom and a body portion, and a bottom and discharge tube portion.
The present invention is an interruptive technology in an industry that has been basically unchanged in 40 years or more. At a 7% annual growth rate the need for manual operators will double in 8 years. Many current factory owners whose current population is 5,000 to 10,000 employees, are having a difficult time today finding enough labor to fill their factories and meet their production schedules.
Further the prior art handmade constructions do not lend themselves to forward automation due to the variances caused by the hand making process.
The methods of the present invention designed for production make this container safer to use.
The methods of operation of the present invention makes this container more environmentally friendly by using less plastic and making it easier to recycle through elimination of the liner. Further because the bag can be made locally to the end user, it will reduce the environmental damage caused by long distance transportation needed to get everything from southeast Asia, for example.
The methods of production in one or more embodiments are also friendlier for the employees. It is physically less demanding and requires little education or training.
Given the level of automation of the present invention, it can help standardize sizing in the industry. This will help improve the efficiencies of every manufacturing plant from the production of the raw materials to the finished bag.
Advantages of heat-sealed bags in accordance with one or more embodiments herein include:
1. Faster and Cleaner—bag construction is an automated process;
2. Lighter and Stronger—the seal strength is stronger and the bag is lighter; and/or
3. Easier Handling—eliminates the need for liners.
In various embodiments, an extrusion coating is used as a bonding coating that is a polyolefin and allows for a heat sealed seam.
In various embodiments heat sealing is automated, precise and contamination free whereas sewing in the prior art is labor intensive and includes a high risk of contamination.
In various embodiments a bag can be manufactured via heat sealing and folded for transport or storage in around 6 minutes, whereas prior art sewing of a bag typically takes 20 minutes or more.
In various embodiments a heat sealed joint retains about 95 percent or more of the fabric strength whereas a prior art sewn seam retains about 63 percent of the fabric strength.
In various embodiments a heat sealed joint retains about 95 percent of the fabric strength which enables less use of fabric in the overall bag.
In various embodiments a heat sealed bag is designed for functionality and no liner enables easy opening and discharge of contents. Prior art sewn bags have complex and difficult spouts.
In various embodiments filled heat sealed bags can be stacked on each other.
In various embodiments, different fabrics can be used for different parts of a bag, e.g., fabrics of differing densities or thicknesses or strengths. For example, a bottom portion can be made from a stronger polypropylene fabric than a top portion. A diaper cover or lift loop panel or body portion or fill spout or discharge tube or top or bottom could all be made of the same fabric or of differing fabrics. In various embodiments one or more fabric portions can be selected from the same material, while one or more other fabric portions can be selected from a different material.
In various embodiments fabrics for each bag portion can be chosen so that some bag portions will have the desired maximum strength, while selecting more cost effective fabrics for other bag portions where less strength is needed.
In various embodiments, one or more of the heat sealing machinery, heat sealing systems, heat sealing assembly line and methods described herein can be used to heat seal polypropylene fabric, e.g., highly oriented polypropylene fabric, to form a bag or container.
In various embodiments, one or more of the heat sealing machinery, heat sealing systems, heat sealing assembly line and methods described herein can be used to heat seal polypropylene fabric, e.g., highly oriented polypropylene fabric.
In various embodiments, one or more of the heat sealing machinery, heat sealing systems, heat sealing assembly line and methods described herein can be used to heat seal polyethylene fabric, e.g., highly oriented polyethylene fabric, to form a bag or container.
In various embodiments, one or more of the heat sealing machinery, heat sealing systems, heat sealing assembly line and methods described herein can be used to heat seal polyethylene fabric.
In various embodiments, one or more of the heat sealing machinery, heat sealing systems, heat sealing assembly line and methods described herein can be used to heat seal polyethylene fabric, to form a bag or container.
In various embodiments, one or more of the heat sealing machinery, heat sealing systems, heat sealing assembly lines and methods described herein can be used to heat seal plastic fabric to form a bag or container.
In various embodiments, one or more of the heat sealing machinery, heat sealing systems, heat sealing assembly lines and methods described herein can be used to heat seal plastic fabric.
In one or more embodiments of making a heat sealed bag, at times a bonding coating will be in contact with a bonding coating in gusseted areas in locations where it is not desired to form a joint. In embodiments wherein a standard fabric coating is on one fabric piece and a bonding coating is on another fabric piece, the overlapping to form the joint area can be done so as to minimize unwanted bonds and to make a bag easier to assemble and heat seal. The overlapping to form the joint area can be done on a standard coating side to help prevent destroying or damaging the bag during heat sealing.
During heat sealing, escaping heat from sealing heads sometimes influences neighboring coatings. Generally, it is desirable to have the overflow of heat to go to a standard coating side. The grip of the standard polypropylene fabric coating to the polypropylene fabric, for example, is very strong, while the grip of a standard polypropylene coating to a standard polypropylene coating is not strong. When separating any bond formed between standard coatings, a bag is not destroyed because the standard coating is not broken off, or pulled from, the fabric. When a bonding coating is bonded to another bonding coating, the bond is so strong that when breaking the bond, the bonding coating pulls away from the bag fabric, damages the fabric, and the bag generally is rejected.
When heat sealing, the interfaces between standard and standard coatings, bonding and standard coatings, and bonding and bonding coatings, needs to be considered. The interface between standard coating to standard coating has less grip, whereas the interface of standard coating to bonding coating, and of bonding coating to bonding coating has more grip and is very strong grip.
When heat sealing a joint with one fabric piece having a bonding coating, and one fabric piece having a standard polypropylene fabric laminate coating, at least three different melting points are present in an overlapped area to be heat fused (1) melting point of the fabric, (2) melting point of the bonding coating, and (3) melting point of the standard coating.
A bonding coating as described herein, for example, a bonding coating including VERSIFY™ 3000, has a lower melting point than a polypropylene standard fabric laminate coating. A polypropylene standard fabric laminate coating has a melting point lower than polypropylene fabric.
In one or more embodiments, during heat sealing, a bonding coating is melted, a polypropylene standard laminate coating is not melted, but can be heated to a softening temperature, and the fabric is not heated to a temperature at which it could be melted or weakened or damaged.
In one or more embodiments, during heat sealing, a bonding coating is melted, a polypropylene standard laminate coating is not completely melted, (e.g., only 15 to 30 percent of the standard laminate coating is melted), and the fabric is not heated to a temperature at which it is melted or weakened or damaged.
VERSIFY™ 3000, which can be used as, or included in a bonding coating, has a melting temperature of around 226 degrees F. (107.8 degrees Celsius), and a softening temperature of around 221 degrees F. (105 degrees Celsius). A standard polypropylene fabric coating, which can include about 70 to 85 percent polypropylene and about 15 to 30 percent polyethylene, has a melting point of about 239 degrees F. (115 degrees Celsius) and a softening point of about 221 degrees F. (105 degrees Celsius). Generally, polypropylene will soften at about 310 degrees Fahrenheit (154 degrees Celsius) and liquify or melt at about 330 degrees Fahrenheit (165.6 degrees Celsius). Polyethylene typically has a melting point of about 190 degrees Fahrenheit (87.8 degrees Celsius). Testing has shown that when heat sealing, a joint formed with a fabric piece having a bonding coating with about 70 percent VERSIFY™ 3000, and another fabric piece with a standard polypropylene fabric laminate coating, when the heat seal bars are set to a temperature of around 290 degrees F. (143.3 degrees Celsius), the center of the gusseted layers is reaching a temperature of about 232 to 234 degrees F. (111 to 112 degrees Celsius). Top or bottom areas of the gusseted layers can be about 5 degrees higher, e.g., about 237 to 239 degrees F. (113.9 to 115 degrees Celsius). When this occurs, the bonding coating is melting but the standard polypropylene coating is not melting (or is not completely melting, or is softening) and a bond is formed between the bonding coating and the standard polypropylene fabric coating. The polypropylene fabric is also not damaged or weakened.
In some embodiments, when forming a bag joint, the bonding coating is melting but the standard polypropylene coating is not melting and a bond is formed between the bonding coating and the standard polypropylene fabric coating, and the bond has sufficient strength as a bulk bag joint, e.g., for a bulk bag that can hold 2,000 to 5,000 pounds (907 to 2,268 kilograms) or more of bulk material.
In some embodiments, when forming a bag joint, the bonding coating is melting but the standard polypropylene coating is not completely melting, and a bond is formed between the bonding coating and the standard polypropylene fabric coating, and the bond has sufficient strength as bulk bag joint, e.g., for a bulk bag that can hold 2,000 to 5,000 pounds (907 to 2,268 kilograms) or more of bulk material.
In some embodiments, when forming a bag joint, the bonding coating is melting but the standard polypropylene coating is not melting but is softening and a bond is formed between the bonding coating and the standard polypropylene fabric coating, and the bond has sufficient strength as bulk bag joint, e.g., for a bulk bag that can hold 2,000 to 5,000 pounds (907 to 2,268 kilograms) or more of bulk material.
A bond formed between a standard polypropylene fabric coating and bonding can be in the range of microns.
During experimentation, matrix testing and tensile strength testing has been performed. A selected test temperature is used when heat sealing one or more bag joint areas to form a heat sealed bag. After completing a bag, pressure is applied to the heat sealed bag until one or more joints of the heat sealed bag breaks. If a bag joint breaks after reaching 90 to 95% of the bags tensile strength, this is evidence that the test temperature applied was high enough to form a bag joint that can work as desired for a bulk bag, and low enough to not damage the bag.
In one or more embodiments, the temperature applied during heat sealing is high enough to produce a bond between coatings that has at least 90 to 95% of the bag strength and low enough to not damage or reduce the strength of the bag fabric.
In one or more embodiments, the temperature applied during heat sealing is about 290 degrees F. (143 degrees Celsius) and can be used when heat sealing a bag that will have at least 90 to 95% of the bag strength and low enough to not damage or reduce the strength of the bag fabric.
In one or more embodiments, the temperature applied during heat sealing can be about 225 to 290 degrees F. (107 to 143 degrees Celsius), and can be used when heat sealing a bag that will have at least about 90 to 95% of the bag strength and low enough to not damage or reduce the strength of the bag fabric.
As described herein, preferably the heat seal bar extends past the edge of the joint to be formed which can help ensure nongraspable edges are formed. When sealing a lift loop patch to the bag body, preferably the end of the patch ends about a quarter inch (0.64 cm) before an edge of the heat element. This allows heat to be absorbed by the outer edge of the patch and by the surface of the body. When this occurs, a portion of the coating can bubble out and harden past the edge of the overlapped fabrics and this can add additional strength to the bond.
In some embodiments, a patch coating can have a thickness of 3 to 3.5 mils (0.08 to 0.089 millimeters).
For a further understanding of the nature, objects, and advantages of the present invention, reference should be had to the following detailed description, read in conjunction with the following drawings, wherein like reference numerals denote like elements and wherein:
Unless otherwise noted herein, the specific parts and materials included in the description and in the figures are examples of parts and materials that may be used in various embodiments of the invention as shown and described herein. Other suitable parts and materials as known in the art may also be used in various embodiments of the inventions as shown and described herein.
One or more embodiments of the apparatus of the present invention relates to a stitchless bulk bag that includes heat sealed joints. In preferred embodiments, a containment area of the bag, e.g., surfaces that can come into contact with material in the bag, includes no stitching, stitch holes, or threads.
In one or more embodiments of the method of the present invention, what is provided is a heat sealing method that does not substantially damage the strength of the polypropylene fabric yet still gets a final joint strength equal to or exceeding the strength of the current sewing methods. During testing, products produced using the method of the present invention have achieved joint strengths of about 90 to 102% of the strength of the polypropylene fabrics which is considerably above the joint strengths of seams achieved through sewing. Another embodiment of the present invention provides joint strengths of about 100 to 102% of the strength of the polypropylene fabrics.
In a preferred embodiment of the present invention, the invention will aid and enable the automation of bulk bag production, thus freeing up the location of factories around the world. Due to the improved joint strength, this invention will enable the use of thinner materials that what is used in the prior art, and accomplish the lifting of similar weights.
In one or more embodiments of the present invention, a suitable bonding coating, for example VERSIFY™ 3000, a product produced by The Dow Chemical Company is applied to the polypropylene fabrics or similar fabrics, and provides up to about 240 lbs of hold or grip per lineal inch (4,286 kilogram/meter) to the polypropylene fabric from a heat seal of about 1½ inches (3.81 cm) across the joint area. In another embodiment, a coating, for example VERSIFY™ 3000, a product produced by The Dow Chemical Company is applied to the polypropylene fabrics or similar fabrics, and provides up to about 200 lbs of hold or grip per lineal inch (3,572 kilogram/meter). In a preferred embodiment, the coating has a melting point which is lower than the melting point of the fabrics being joined together. The method of heat sealing is an improvement over the known art in the woven fabrics industry today.
The dimensions of the joint or sealed areas may vary based on the particular application for which the joined fabric will be used.
A suitable bonding coating can be a propylene plastomer and elastomer, for example Versify™ 3000. The coating may contain for example about 50% to 90% polypropylene based polymer and about 10%-50% polyethylene, by weight.
In a coating to be used in a preferred method of the present invention for heat joining polypropylene fabric, one can use about 10-99%, preferably about 20-95%, more preferably about 30-95%, and most preferably about 75-90% propylene plastomers, elastomers, or combinations thereof;
one can use about 0-5% additives for color, anti-static, or other purposes (these do not materially affect the performance of the coating, and are typically minimized as they are more expensive than the propylene and polyethylene);
the balance is preferably polyethylene plastomers, elastomers, or combinations thereof.
Preferably, the propylene plastomers, elastomers, or combinations thereof have a density of about 0.915 to 0.80 grams per cc, and more preferably about 0.905 to 0.80 grams per cc. Preferably, the polyethylene plastomers, elastomers, or combinations thereof have a density of about 0.91 to 0.925 grams per cc. Typically, one should use at least about 5% low density polyethylene to make the coating run, and preferably at least about 10%.
In one or more preferred embodiments of the present invention, the fabrics are only being heated to the melting point of the coating which is lower than the melting point of the fabrics being joined together. In one or more preferred embodiments of the present invention, the joining temperatures are at least about 5 degrees less than the melting point of the polypropylene fabrics to be joined. Different polypropylene fabrics will have different melting points, and in one or more embodiments of the method of the present invention, the joining temperatures are at least about 5 degrees less than the melting point of the particular polypropylene fabrics to be joined. An example polypropylene fabric may have a melting point of about 320 degrees Fahrenheit (176.7 degrees Celsius), and thus in an embodiment of the present invention, the coating will be heated to about 315 degrees Fahrenheit (157.22 degrees Celsius). By using a lower heat than the polypropylene fabrics, the method of the present invention does not damage or reduce the strength of the fabric as typically happens when using the prior art high heat formulas for heat welding. Further, in one or more embodiments of the present invention, the clamping pressure used to make the seal is designed to be low enough (for example about 7 psi (48 kilopascal)) to leave the coating largely in place and the materials to be joined, largely separated by the coatings. Clamping pressures may also be lower, for example under about 2 psi (13.8 kilopascal). Typically, in the prior art heat sealing methods, the clamping process is designed to purposefully melt and push aside any coatings on the fabric and join the fabric yarns directly. Naturally, when any part of the fabric yarns are heated to and past their melting point and that is combined with high pressure (for example 20 psi (137.9 kilopascal)), the yarns are thinned out, weakened and partially crystallized.
It is an objective of the present invention to heat fuse fabrics together. In one or more preferred embodiments of the present invention, fabrics are not being heated up past their melting points, which is useful in preventing degradation of the strength of the fabric.
In the present invention, using low heat and low pressure, only the coatings are being joined. This leaves the fabric completely undamaged and unweakened. In fact, the strength of the coating now can add to the overall joint strength rather than being squeezed out in the current methods. With the resulting joint strengths, the present invention enables lifting of higher weights with less material, than can be done with the prior art methods of sewing fabrics together.
As previously, discussed, in one or more preferred embodiments, the coating materials have a melting point lower than the fabrics to be joined. In one or more embodiments, the coating materials in the process may be any suitable material or materials which may be used to successfully carry out the process, and can be selected from a range of coating materials. A suitable coating, for example, may be a propylene plastomer and elastomer, for example VERSIFY™ 3000, a product produced by The Dow Chemical Company. A suitable coating may contain about 50% to 90% polypropylene based polymer and about 10%-50% polyethylene, by weight. VERSIFY™ is a registered trademark of The Dow Chemical Company for propylene-ethylene copolymers used as raw materials in the manufacture of films, fibers and a wide variety of molded plastic objects; propylene-ethylene copolymers used as raw materials in the manufacture of compounds to make coated fabrics, artificial leather, soft touch grips, shoe stiffeners and flexible roofing membranes.
In one or more preferred embodiments of the present invention, for a bonding coating, the method utilizes a mixture of a minimum of about 70% pure VERSIFY™ 3000 and about 25% polyethylene and about 5% of additives such as UV protection and colors. In testing, when using about 100% pure VERSIFY™ 3000, the method of the present invention achieved up to about 96% to 102% joint efficiency in a shear joint tensile test, while at about 70% VERSIFY™ 3000, about 91% to 95% joint efficiency has been obtained in the same test. (The resulting percentages are based on the average strength of the fabric tested. There is generally approximately about a 5% variable strength in any section of fabric tested.) Turning now to the figures, the chart shown in
After the bag is made and filled, the pre-hemmed seam will be in the position shown in
When labor is taken into account as well, it is easily seen that the sewing operation is a very large factor in determining the final cost of making bulk bags.
Taking the same fabrics, and using the fusion heat seal seam method of the present invention, the graph shown in
When 95% of the original strength is being maintained through the fabric connections, equal fabrics may be used to carry heavier loads, or less fabric can be used to carry the same load. An embodiment of the present invention thus may provide a 50% gain in strength over the sewn seams.
The fusion heat seal seam or joint not only creates a stronger seal, but it does it in a significantly different manner. The fusion heat seal seam or joint of the present invention enables new bulk bag designs that will be able fill the needs of the bulk bag industry.
In the prior art, due to the nature of sewing machines and the size of bulk bags, the vast majority of seams must be sewn in an edge to edge peel position. The throat of a sewing machine is not big enough to easily allow an entire bulk bag to pass through the throat of the machine. Therefore, sewing is typically designed to place all seams in an edge to edge position as shown in
Once a sewn seam prior art bag is made and filled, the sewn seam then is put into a peel position that depends entirely on the strength of the combination of the thread and needle punctured fabrics.
In
The fusion heat seal seam or joint of one or more embodiments of the present invention is preferably formed by overlapping the fabrics to give the seal a wide shear area for strength. In an embodiment of the present invention, the fusion seam will get about 95% of the original fabric strength. In one or more preferred embodiments, there will be an overlap of about 1½ to 2 inches (3.81 cm to 5.08 cm). This saves a minimum of about 2 inches (5.08 cm) of fabric in every joint as the prior art sewn method has about 2 inches (5.08 cm) of doubled fabric layers on both sides of the seam.
In one or more embodiments of the present invention the width of the overlap can be much smaller, for example 0.5 inches (1.25 cm) to save even more fabric.
It is preferable that the seams be sealed in a manner so that no graspable edge is left on any exterior seams of the bag. This will discourage any attempt to rip the seal open in the peel position which is the weak direction of the fusion joint.
In one or more embodiments of the present invention, a preferred method is to overlap the fabric portions only about 1½ inches (3.81 cm) and to center this overlapped area under a seal bar 21, which can be about 2 inches (1.25 cm) wide, for example, as shown in
About a ¼ inch (0.64 cm) transitional area, for example, is small enough to prevent damaging heat from overcoming the smaller material volume of the single layer and allows for some small misplacement of the fabric edge lineup. Alternatively, a transitional area can be about ⅛ to ¼ inches (0.32 to 0.64 cm).
In one or more embodiments of the method of the present invention, a pulse heat process is used. By using impulse heat, the top or highest temperature can be controlled and held to a desired amount of heat, in a desired range of temperature, for a desired amount of time. This then allows the process to bring the material temperatures up to the desired level without going so high as to damage the fabrics but to also hold the temperature there long enough to allow a thorough and even heating of the joint area. In one or more embodiments, the heat seal bar can remain in place on the fabric during a cooling time. This can help to ensure that a bond is formed between the fabrics. A cooling time can be 30 to 90 seconds, for example.
It is also useful to the process to keep equal amounts of materials under the seal at all times. The impulse heat process is injecting equal heat throughout the sealing process. If an uneven amount of materials under the seal bar is too diverse, then areas with less materials may absorb more heat than desired and material damage can occur.
In
One or more embodiments of the present invention involves stacking this process and creating multiple seals simultaneously. When stacking the process, placement of materials should be considered and keeping material amounts equal throughout will enable safe repeatability of the sealing process.
It is a further object of the present invention that a product made by heat sealing versus sewing will have many advantages such as reduced or no sifting in a bag containment area, reduced manpower, thinner materials, reduced or no contamination and improved repeatability through automation.
What has been described and shown so far is the difference between sewing seams and heat sealing to make a simple seam using polypropylene fabrics. Hereafter, the construction of bulk bags, that may routinely carry one ton of dry flowable materials, for example, will be discussed.
An objective of the present invention is to find ways to reduce the cost of making a product commonly called by several names. These names include bulk bags, Flexible Intermediate Bulk Containers or FIBCs, Big Bags or even Super Sacks (a trademark name of B.A.G. Corporation). Herein the product has been and will be referred to mostly as bulk bags.
The present invention has useful applications with bulk bag production, and is also useful to a number of other packages or products, for example smaller bags used to carry about 25 to 100 pounds (11 to 45 kilograms). The present invention can also be useful in production of bags designed to carry about 100 to 500 pounds (45-226 kilograms) of material. Other products that will benefit from the present invention include products stored or transported in flexible fabric packaging, wherein a sterile and air tight package is preferred.
Current bulk bag technology using sewing machines typically travels stitch by stitch around every inch or (2.54 cm) of seam on every part of the bag on an individual basis. In one or more embodiments of the present invention, the invention can simplify this process to create a productive system that can seal or join the fill spout to the top sheet, the top sheet to the bag body, the bottom sheet to the bag body, and the bottom discharge spout to the bottom sheet in a single moment or step. This eliminates a tremendous amount of labor and time.
Further, in one or more embodiments of the present invention each heat sealed seam can be approximately 50% stronger than the sewn seam. Because each heat sealed joint or seam requires less fabric than the sewn seam, the present invention enables production of a fabric bag that is demonstrably less expensive and more economical to make.
Use of heat sealing is known in the art. No matter what the shape of the seal to be made is, heat bars can be shaped to accomplish that seal and that shape. In one or more embodiments of the present invention, a square formed heat bar and structures can be used to hold the fabric in place to allow the joining of the bottom of the bag to the sidewalls to make a joint. Such equipment, however, may be large, bulky and expensive. Additional steps to complete the product and additional machines may be needed.
In one or more embodiments of the present invention, the method comprises using the fusion heat sealing method of the present invention for production of bulk bags, wherein individual joints are sealed sequentially, one after another. In another embodiment of the present invention, fewer steps and machines are used in fusion heat sealing a bulk bag. An objective of the present invention is to simplify the number of steps when producing a bulk bag, as compared to prior art sewing methods.
There are many prior art designs in the bulk bag market but most of these designs fall into two basic categories. The body of the bag may be made from numerous pieces of flat panels sewn together or the body of the bag may be made from a single piece of tubular fabric that has no vertical seams.
All of the basic designs can be made using one or more embodiments of the system and method of the present invention. A preferred embodiment of the present invention will start with a tubular woven body.
Many bulk bags have a fill spout, a top panel, a circular woven body panel, a bottom panel and a discharge spout. The two spouts can be made with tubular fabric with no seams. The body of the bag may be made with tubular fabric with no seams. The top and bottom panels are generally square flat panels with a hole or opening cut into them to accommodate the spouts that must be attached to them.
Thus,
In one or more embodiments of the present invention, a bulk bag may be produced, using a fusion heat seal process, in a single step. In preferred embodiments, the fabric pieces will be gusseted and placed in position for the heat fusion sealing process. The
In a preferred embodiment the coating side of the fabrics is on the outside of the tubes and on the inside of the flat panels, so that the coatings will be facing each other when the bag is formed.
These coating positions can be reversed and put inside of the tubes and outside of the flat panels for top and bottom, but since coating naturally comes on the outside of tubular fabric, a preferred method is the one shown in the drawings.
The folding arrangement as described above enables each piece to fit inside or around the piece it will be connected to in the production process, to form the desired overlap areas for a bag joint, as shown in
Fill spout 36 as shown in
Once the fabrics portions are positioned together with desired overlap areas for desired bag joints, a bag 10 is ready to seal as shown in
Coating 19 can be a bonding coating, e.g., a propylene based plastomers or elastomers coating such as VERSIFY™ 3000, or coating 19 can be a standard polypropylene fabric coating. In the overlapped joint areas 41, a bonding coating on piece of fabric can face another bonding coating on another piece of fabric, or a bonding coating on one piece of fabric can face a standard polypropylene fabric coating on another piece of fabric. Note that a bag joint will not be formed in areas where a standard polypropylene fabric coating on one piece of fabric is facing a standard polypropylene fabric coating on another piece of fabric. A buffer material can be positioned in areas between a bonding coating and a bonding coating, or in areas between a bonding coating and standard polypropylene coating if a bag joint is not desired in the area and heat might travel to or through that area.
This results in a total of 8 layers of fabric at all points from bottom to top. In
By lining up multiple layers in this fashion, the heat sealing method of the present invention is able to completely join the top to the body panel in a single action. When the structure as depicted in figures in 15-16 is collapsed, the structure is always coating 19 to coating 19 for joint creation and fabric 13 to fabric 13 for not creating a joint. In the drawings the gussets may be positioned so as to fit together and during production, fabrics are collapsed to a flat condition.
All four joints are made in the same manner.
Various embodiments of the method of the present invention using impulse sealing to make joints with heat traveling through multiple fabric layers and without exceeding the safe temperature limit, comprises controlled heating that will not rise above the desired level which is less than the melting point of the polypropylene fabric.
In preferred embodiments, in order to get the entire group of intended joints to the right temperature level without damaging the fabric strength, time will be employed to allow the required heat to become universal throughout the 8 layers of materials.
Further, it will be useful if the heat mechanisms are mirrored on the top and bottom so that heat may need to travel only 50% of the total thickness. This process may also be achievable with one heating element by using a greater time for the heat to travel throughout the entire stack of layers of fabrics. A preferred method uses heating elements on both top and bottom of the stack.
In an embodiment of the present invention, a single machine with 4 heating elements on top and four heating elements on the bottom can effectively seal, in a single action, all four of the joints shown in
The fabrics can be placed and positioned under the sealing mechanisms so that the heat sealing bars cover the area to be joined plus preferably about a ¼ inch (0.64 cm) overlap, for example, to enable sealing of all edges and to also make them ungraspable. In an embodiment of the present invention, the mechanisms can control heat, time and pressure. When this is done, the bags can be put together in a completely repeatable and dependable fashion with this stage of production requiring a single automatable machine.
When making bulk bags in this manner, different sizes of bags can be made by simply changing the length of the body panel. This would require only the movement of two heating elements to match the new distance between the top and bottom panel attachments. The relationship or distance between the spout joints and the top and bottom panel would be unchanged, in this embodiment.
The method of the present invention may also be used to create different designs of bulk bags, for example baffle bags or bags with lifting loops, with heat fused seals or joints.
Preferred embodiments of the heat sealing system eliminate the need for threads and the resulting contamination that often occurs when a cut piece of thread is left inside a bag. Preferred embodiments also reduce contamination from machinery, e.g., prior art sewing machines, coming into contact with various parts of the bag. Heat sealing equipment in the present invention also preferably do not make contact with interior surfaces of the bag. Preferred embodiments also reduce or eliminate human contact with the inner surfaces of the bag.
Since the heat sealed seams or joints are solid without any needle holes, the method and system of the present invention eliminate any need for sift-proofing that is often required for stitched bulk bags. The method of the present invention provides a bag that is at least nearly air tight or is air tight.
Due to the airtightness and the cleanliness, the present invention can eliminate the need for polyethylene liners that are often added to the inside of the bulk bag for cleanliness and/or moisture control. This will reduce the amount of plastic used in the industry and therefore reduce the amount of materials eventually going into landfill.
Notably all four of the seams shown in a preferred embodiment of
Thus, in the method of the present invention for automating production of flexible bags, packages or containers, it should be understood that this method can cover all kinds of flexible bags, packages or containers.
As previously discussed, the bulk bag industry uses a highly oriented woven polypropylene fabric. This is based on a cost versus strength matrix. Polypropylene has historically been lower in cost per pound (kilogram) and historically stronger than similar polyethylene fabric by about 30% in tensile strength. While it was always possible to use a thicker polyethylene material to make bulk bags, there has been limited interest in using that material due to the ensuing cost of getting the needed strength. Further, polyethylene fabrics have a lower melting point than polypropylene fabrics so once again, polypropylene has been a preferred material for nearly 40 years in this industry. Polypropylene is also a very inert material. It is unaffected by almost every chemical. This also makes it a good choice for making packaging bags. With all of these benefits for the industry, one area where polypropylene falls short of polyethylene, has been the result of polypropylene's inertness and its strength due to high levels of orientation.
Because of this inertness, the entire industry has relied upon a physical connection of materials for the container construction. It has relied nearly 100% on sewing as the method of construction.
One of the common alternate methods of connection to sewing that is automatable has been to use heat to form joints. When polyethylene fabrics are used, this is very common. But polypropylene crystallizes at the level of heat needed to form a joint. This crystallization destroys the joint strength rendering this method previously unusable with polypropylene fabrics. There are currently no known methods of heat sealing polypropylene fabrics together that create usable seams for the construction of polypropylene bags such as bulk bags that can carry tremendous weights, e.g., about 5,000 pounds (2,268 kilograms).
As stated earlier, the sewing process is very labor intensive and very poorly suited for any form of automation. Sewing machines have very high speed parts moving to allow sewing stitches to be applied at thousands of stitches per minute. At these speeds, even if the machines were operated robotically, needles and threads are continually breaking and needing human repair to be put back into operation. Therefore, due to the inability to run without constant human support, the bulk bag industry has never been able to automate its production in an efficient and cost effective manner. This has led to the loss of all of these jobs to overseas plants located in low labor cost countries.
Therefore, there is a need for an automatable system of bulk bag construction that will reduce the high levels of labor currently required in the construction of bulk bags. This will allow the production to be positioned close to the end users and eliminate the extremely long lead times and high inventory needs that the industry suffers with under the current sewing construction methods.
An embodiment of the method of the present invention comprises a method of constructing woven fabric bags using a novel and unique heat sealing method. Use of a heat sealing process is well known and quite common in the joining of woven polyethylene fabrics. It is commonly understood that a joint efficiency of 80% to 85% is an extremely good joint efficiency level. Many operations accept much lower joint efficiencies that range down into the 70's of the percentage of efficiencies.
In the sewn seams, the efficiency is often only 65%. The strength of the polypropylene fabric takes these joint efficiencies into consideration when choosing the strength of the fabric that will be used in the construction of the final container.
Current methods of heat sealing usually involve high enough heat and high enough applied pressure to melt the basic fabrics and join them together. This method purposefully, melts any applied coating and squeezes it aside through the high pressure levels so that the base woven materials can be joined together. This method has been successful, with polyethylene fabrics for example, for several decades. It was necessary because the strength being relied upon came from the woven fabrics. The coatings that were generally applied, were applied for the purpose of providing dust and/or moisture control.
Because polypropylene is so inert, the coatings being applied had low attachment strength to the woven fabrics. Therefore, if they were to be used as the attachment point by welding the applied coatings together, the resulting strength would have no real relationship to the strength of the fabric. The resulting joint strength would only be related to the strength of the coating's attachment to the woven fabrics. When conducting testing with regard to the present invention, of making joints that relied on the strength of the coating's attachment using the present technology, results showed about a 27% joint efficiency on the particular strength of materials tested. In these tests, it was never the fabric that broke. It was always the coating detaching from the fabric that caused the joint to fail.
In the present invention, a coating that can be applied in a standard extrusion coating method attaches so completely to the polypropylene fabrics that it is no longer necessary to apply high pressure that will squeeze the coating out from under the heated jaws of the sealing mechanism. In fact, by sealing under less than 10 psi (68.9 kilopascal), it is an objective of this invention to utilize the strength of the applied coating as part of the strength of the final heat seal. The fabric itself is nearly undamaged during this heat sealing method. In an embodiment of the present invention, only the coating is intended to be melted to create the joint. Tests results show achievement of over 90% joint strengths. Some tests results are running up as high as 100% of the strength of the coated materials that have not been sealed. However, the resulting strength of the joints many times exceeds the strength of the original fabric itself prior to it having been coated.
Therefore, in an embodiment of the method of the present invention, the method of heat sealing creates seams that are sometimes actually stronger than the original fabric before any process begins. Considering that the current methods are working with sewn seams that have a 65% joint efficiency, it is an objective of the present invention that this heat sealing method will make heat sealed joints with minimal damage to the original fabric, if any, and will allow not only lower costs through automation to reduce labor costs, but will provide many opportunities to reduce fabric weights and thicknesses used in making bulk bags while providing similar overall strengths through the higher seam efficiencies. An example would be as follows; if the sewn fabric had a tensile strength of 200 pounds per inch (3,572 kilograms/meter), after being sewn the seam would have a strength of 65% of the 200 pounds per inch (3,572 kilograms/meter) or only 130 pounds (58 kilograms). With a 90% joint efficiency, a fabric that had an original strength of 150 pounds per inch (2,678 kilograms/meter) would still create a seam strength of 135 pounds per inch (2,410 kilograms/meter). This would allow a 25% reduction in the strength of the fabric to create an equal seam. This obviously then will lead to long term reductions on the amount of fabrics needed with this system to create bags with similar strengths.
All seams have at least two measurements that are critical to its success. These are generally called shear and peel tests.
In the shear tests, the joint is made with two ends of the material being joined at opposite ends of the joint area. When the free ends of the materials are pulled in opposite directions, the entire sealed area supports the joint efficiently. This results in the highest possible demonstration of the sealed joint efficiency.
In the peel test, two free ends of the test materials are on the same side of the joint. In this case, when the two free ends are pulled apart, only one edge of the seal is stressed at any one time. This results in the peeling of the joint as the ends are pulled apart. This typically results in the lowest joint efficiency.
An embodiment of the present invention is illustrated in
A stitchless bag 50 preferably has no stitches or sewn seams in a containment area of the bag, i.e., on a surface of the bag 50 that comes into contact with bulk material contained within the bag 50. In a preferred embodiment the bag 50 has no vertical or longitudinal seams or joints in a containment area. Preferably the bag 50 has horizontal or transversely extending joints around a circumference of the bag at connections between a fill spout 57 and top 51, a top 51 and body 53, a body 53 and bottom 52, and a bottom 52 and discharge tube portion 58. Preferably bulk bag 50 comprises highly oriented polypropylene fabric. As shown in
Fill spout 57 preferably comprises a first side 112, second side 113, front side 115 and back side 116, with unsealed or open top 80 and open bottom 54 portions (see
Preferably exterior surface 131 of fill spout 57 comprises a heat sealing coating or layer at least in lower portion 111 of fill spout 57, which can be a fusion coating 191 or a standard polypropylene fabric coating 192. As will be discussed further below in describing construction of bag 50, preferably exterior surface 131 of fill spout 57 comprises a standard industry coating 192 at least in a lower portion 111 of fill spout 57 which can form part of fusion area 65 and joint 126 with top 51. (See
Similarly, discharge tube 58 comprises a first side 171, second side 172, front side 173 and back side 174, with unsealed or open top 175 and bottom 176 portions (see
Top 51 preferably starts with a piece of fabric having a bottom side 100) and upper side 101 and can comprise four tabs or flaps 121, 122, 123, 124 on upper side 101, positioned around an opening 76 (see
Top 51 further includes lower portion 81 extending around a circumference of interior surface 132 of top 51 which can be heat fused to upper portion 161 of body 53 to form joint 127 in heat sealing or fusion area 66, around an entire circumference of body 53 (see
Preferably interior surface 132 of top 51 comprises a heat sealing coating or layer at least on flaps 121, 122, 123, 124, that will form a joint with portion 111, which can be a fusion coating 191, or a standard polypropylene fabric coating 192. Preferably interior surface 132 of top 51 also comprises a heat sealing coating or layer in lower portion 81 for forming a joint with upper portion 161 of body 53. As will be discussed further below in describing construction of a bag 50, preferably interior surface 132 of top 51 has a bonding coating 191 at least on interior surface 132 of flaps 121, 122, 123, 124 and in lower portion 81, which allows for the least amount of fabric with the more expensive fusion coating in the overall bag construction and is important for cost reduction in bag production.
Bottom 52 preferably starts with a piece of fabric having a bottom side 104 and upper or top side 94 and can comprise four tabs or flaps 153, 154, 155, 156, positioned around an opening 78 (see
Bottom 52 preferably includes upper portion 83 around a circumference of interior surface 136 that can be heat sealed to lower portion 162 of body 53 forming joint 128 in fusion or sealing area 67 around an entire circumference of body 53 on lower portion 162 of body 53 (see
Preferably interior surface 136 of bottom 52 comprises a heat sealing coating or layer at least on flaps 153, 154, 155, 156, which can be a fusion coating 191 or a standard polypropylene fabric coating 192. Preferably interior surface 136 of bottom 52 also includes a heat sealing coating or layer in upper portion 83 for forming a joint with lower portion 162 of body 53. As will be discussed further below in describing construction of bag 50, preferably interior surface 136 of bottom 52 comprises a fusion coating 191 or layer at least on interior surface 136 of flaps 153, 154, 155, 156, on interior surface 136 in upper portion 83 which allows for the least amount of fabric with the more expensive fusion coating in the overall bag construction.
Body 53 preferably includes an open or unsealed top portion 168 and open or unsealed bottom portion 169, a first side 163, second side 164, front side 165 and back side 166. Body 53 also preferably has an upper portion 161 on exterior surface 135 that can be included in fusion or sealing area 66, and placed in contact with lower portion 81 of top 51 at a desired location where joint 127 can be formed on stitchless bag 50. Body 53 also preferably includes a lower portion 162 on exterior surface 135 that can be included in fusion or sealing area 67, and positioned in contact with upper portion 83 of bottom 52 at a desired location for forming joint 128.
It should be noted that as described herein with regard to a fusion bag 50 and the method for forming same, a standard polypropylene fabric coating 192 will only act as a heat sealing coating in any given fusion or sealing area, when it is positioned in contact with a bonding coating 191. If a standard polypropylene fabric coating 192 is present on fabric in areas that are not fusion areas, wherein a standard polypropylene fabric coating 192 is in contact with another standard polypropylene fabric coating 192, the standard coatings do not act as a heat sealing coating that can form a heat fused joint for a bulk bag as described herein. When a standard fabric polypropylene heat sealing coating 192 is in contact with another standard fabric polypropylene heat sealing coating 192 and heat is applied, any bond formed is not strong enough to act as a bag joint and if the bond is broken the bag fabric has minimal or no damage.
Joint 126 preferably provides an air tight sealed connection between fill spout 57 and top 51. Joint 126 can be formed in fusion or heating sealing area 65 and is preferably a heat sealed joint between fill spout 57 and top 51 (see
To form a joint 126, fill spout 57 can be positioned on a surface with back side 116 resting on the surface, and front side 115 facing upwards (see
Top 51 is preferably folded in a triangular configuration and positioned on a surface so that top back side 144 rests on the surface with top front side 143 facing upwards (See
Folded lower portion 111 of fill spout 57 can be positioned through opening 76 of folded top 51, preferably extending to about the bottom of flaps 121, 122, 123, 124, wherein interior surface 132 of flaps 121, 122, 123, 124 are in contact with exterior surface 131 of lower portion 111 including within gussets 117, 118. When positioned in this manner, the heat sealing coating which is preferably a bonding coating 191 on interior surface 132 of each flap is in contact with a heat sealing coating or layer, which preferably is a standard industry coating 192, on lower portion 111. The overlapped fabric layers of flaps 121, 122, 123, 124, and lower portion 111 can form heat sealing or fusion area 65.
Heat is preferably applied to heat fusion or sealing area 65 with heating travelling from exterior surface 133 of top 51 to each coating on each layer of fabric in heat fusion or sealing area 65. Given the two-dimensional configuration and positioning of fill spout 57 within opening 76 of top 51, this enables formation of joint 126 around an entire circumference of fill spout 57 or on each side of fill spout 57, e.g., if flaps are used, in one heat sealing step. Preferably low enough heat is applied so that the polypropylene fabric is not melted or damaged, but high enough heat is applied so that heat travels through each layer of fabric in fusion or sealing area 65. Heat can be applied to fusion or sealing area 65, via a heat sealing bar. Preferably heat is applied with a heat sealing bar having a rocking motion which helps ensure even application of heat to all layers in a heat fusion or sealing area. Heat can be applied from either upper or lower directions, or both directions to heat sealing area 65.
Lower portion 111 of fill spout 57, which preferably extends transversely around a circumference of exterior surface 131 of fill spout 57 preferably has a longitudinal length of about 1.5 inches (3.81 cm), and can be measured starting from a bottom most point of fill spout 57. Lower portion 111 can also have a longitudinal length of about 1 to 2 inches (2.54 to 5.08 cm) or any other desired length. Flaps 121, 122, 123, 124 also preferably have a longitudinal length of about 1.5 inches (3.81 cm), or can also have a longitudinal length of about 1 to 2 inches (2.54 to 5.08 cm), or other desired longitudinal length. The longitudinal length of flaps 121, 122, 123, or 124 can be measured from the bottom most point of each flap, e.g., at fold line 185 or the bottom of a slit 75. Preferably the longitudinal length of flaps 121, 122, 123, 124 corresponds to a longitudinal length of lower portion 111, and the dimensions of an overlapped portion of flaps 121, 122, 123, 124, can define the dimensions of fusion or sealing area 65.
Similarly, joint 129 preferably provides an air tight, or at least a nearly air tight, sealed connection between discharge tube 58 and bottom 52 (see
Bottom 52 is preferably folded in a triangular configuration and positioned on a surface so that bottom back side 148 rests on the surface with bottom front side 147 facing upwards. Flaps 153 and 155 can be aligned so that interior surface 136 of flap 153 rests on interior surface 136 of flap 155. Interior surface of flap 154 can be drawn towards a center 152 and interior surface of flap 156 can also be drawn towards center 152, without either flap extending all the way to center 152. As shown in
Upper portion 177 of folded discharge tube 58 can be positioned through opening 78 of folded bottom 52, preferably extending to about the bottom of flaps 153, 154, 155, 156, wherein interior surface 136 of flaps 153, 154, 155, 156 are in contact with exterior surface 139 of upper portion 177 of discharge tube 58 including within gussets 178, 179. When positioned in this manner, a heat sealing coating which is preferably a bonding coating 191 on interior surface 136 of each flap 153, 154, 155, 156 is in contact with a heat sealing coating or layer which preferably is a standard industry coating 192 on upper portion 177, with fabric without heat sealing coatings being in contact with other fabric without heat sealing coatings. The overlapped fabric layers of flaps 153, 154, 155, 156, and upper portion 177 can form heat sealing or fusion area 68.
Heat is preferably applied to exterior surface 137 of bottom 52 traveling through fusion or sealing area 68 to each coating on each layer of fabric in heat fusion or sealing area 68. Given the two-dimensional configuration and positioning of discharge tube 58 within opening 78 of bottom 52, which is also in two-dimensional configuration, this enables formation of joint 129 around an entire circumference of discharge tube 58 and/or on each side of discharge tube 58 if flaps are use, at once, in one heat sealing step. Heat can be applied from either upper or lower directions, or both directions to heat sealing area 68.
Preferably low enough heat is applied so that the highly oriented polypropylene fabric is not melted or damaged, but high enough heat is applied so that heat travels through each layer of fabric in fusion or sealing area 68. Heat can be applied to fusion or sealing area 68, via a heat sealing bar. Preferably heat is applied with a heat sealing bar having a rocking motion which helps ensure even application of heat.
Upper portion 177 of discharge tube 58, which preferably extends transversely around a circumference of exterior surface 139 of discharge tube 58, preferably has a longitudinal height of about 1.5 inches (3.81 cm) and can be measured starting from an upper most point of discharge tube 58. Upper portion 177 also can also have a longitudinal height of about 1 to 2 inches (2.54 to 5.08 cm), or any desired height. Flaps 153, 154, 155, 156 also preferably have a longitudinal height of about 1.5 inches (3.81 cm), and can be measured from the bottom most point of each flap, e.g., at fold line 185 or the bottom of a slit 77, or can also have a height of about 1 to 2 inches (2.54 to 5.08 cm) or other desired height. Preferably the height of flaps 153, 154, 155, 156 corresponds to the height of upper portion 177, and the dimensions of the overlapped portion of flaps 153, 154, 155, 156 and upper portion 177 can define the dimensions of fusion area 68.
Top 51 and bottom 52 can simultaneously be connected to body 53, or alternatively in sequence.
Gussets are also preferably formed in body 53, wherein interior surface 134 of first side 163 of body 53 is drawn towards center 170 to form gusset 159, and interior surface 134 of second side 164 is drawn towards center 170 to form gusset 160. Preferably the interior surface 134 of each side 163, 164 is drawn near center 170 but does not contact center 170. Also, preferably exterior surface 135 of body 53 has a heat sealing coating or layer at least in upper and lower portions 161 and 162 that can be a fusion or bonding coating 191 or a standard polypropylene fabric coating 192. Preferably when top 51 and bottom 52 have a fusion of bonding coating 191 on interior surfaces 132, 136, body 53 has a standard industry coating 192 on exterior surface 135.
To form joint 127, upper portion 161 in two-dimensional configuration of body 53 is placed within bottom open portion 102 of top 51 in two-dimensional folded configuration, wherein interior surface 132 of lower portion 81 of top 51, including in gussets 149, 150 are in contact with exterior surface 135 of upper portion 161 of body 53, including in gussets 159, 160. The overlapped fabric areas of lower portion 81 of top 51 and upper portion 161 of body 53 can define heat fusion area 66. Heat is preferably applied to heat fusion area 66 with heating travelling from exterior surface 133 of top 51 in lower portion 81 to the heat sealing coating on each layer of fabric in fusion area 66. Given the two-dimensional configuration and positioning of upper portion 161 of body 103 in contact with lower portion 81 of top 51, through open portion 102 of top 51, this enables formation of joint 127 around an entire circumference of upper portion 161 of body 53 at one time, in one heat sealing step. Preferably low enough heat is applied so that the polypropylene fabric is not melted or damaged, but high enough heat is applied so that heat travels through each layer of fabric in fusion area 66. Heat can be applied to fusion area 66, via a heat sealing bar. Preferably heat is applied with heat sealing bar having a rocking motion which helps ensure even application of heat to all fabric layers in the heat fusion area. Heat can be applied from either upper or lower directions, or both directions to heat sealing area 66.
To form joint 128, lower portion 162 in two-dimensional configuration of body 53 is placed within upper open portion 103 of bottom 52 in two-dimensional folded configuration, wherein interior surface 136 of upper portion 83 of bottom 52, including in gussets 178, 179 are in contact with exterior surface 135 of lower portion 162 of body 53, including in gussets 159, 160. The overlapped fabric areas of upper portion 83 and lower portion 162 can define heat fusion or sealing area 67. Heat is preferably applied to heat fusion area 67 with heating traveling from exterior surface 137 of bottom 52 in upper portion 83 to the heat sealing coating on each layer of fabric in fusion or sealing area 67. Given the two-dimensional configuration and positioning of lower portion 162 of body 53 in contact with upper portion 83 of bottom 52, through open portion 103 of bottom 52, this enables formation of joint 128 around an entire circumference of lower portion 162 of body 53 at one time, in one heat sealing step. Preferably low enough heat is applied so that the highly oriented polypropylene fabric is not melted or damaged, but high enough heat is applied so that heat travels through each layer of fabric in fusion area 67. Heat can be applied to fusion area 67, via a heat sealing bar. Preferably heat is applied with heat sealing bar having a rocking motion which helps ensure even application of heat. Heat can be applied from either upper or lower directions, or both directions to heat sealing area 67.
Upper portion 161 of body 53 preferably has a longitudinal length of about 1.5 inches (3.81 cm) and extends transversely along the circumference of body 53. Upper portion 161 can also have a longitudinal length of about 1 to 2 inches (2.54 to 5.08 cm) or any desired longitudinal length. Similarly, lower portion 81 of top 51 preferably has a longitudinal length of about 1.5 inches (3.81 cm). Lower portion 81 can also have a longitudinal length of about 1 to 2 inches (2.54 to 5.08 cm) or any desired longitudinal length. When lower portion 81 is overlapped with upper portion 162, it can define the dimensions of fusion or sealing area 66.
Lower portion 162 of body 53 preferably has a longitudinal length of about 1.5 inches (3.81 cm). Lower portion 162 can also have a longitudinal length of about 1 to 2 inches (2.54 to 5.08 cm) or any desired longitudinal length. Similarly, upper portion 83 of bottom 52 preferably has a longitudinal length of about 1.5 inches (3.81 cm). Upper portion 83 can also have a longitudinal length of about 1 to 2 inches (2.54 to 5.08 cm) or any desired longitudinal length. When upper portion 83 is overlapped with lower portion 162, it can define the dimensions of fusion or sealing area 67.
As indicated, top 51 and bottom 52 can simultaneously be connected to body 53 with use of two different sealing bars, one applying heat in fusion or sealing area 66, and one applying heat in fusion or sealing area 67, simultaneously.
In various embodiments, each joint 126, 127, 128, 129 can be formed in sequence. In other embodiments, two or more joints of joints 126, 127, 128, 129 can be formed simultaneously. In other embodiments, three or more joints 126, 127, 128, or 129 can be formed simultaneously. In yet other embodiments, all joints 126, 127, 128, 129 can be formed simultaneously.
In various embodiments, each step of folding each of the top 51, bottom 52, body 53, fill spout 57, and discharge tube 58 is done manually. In various embodiments, each step of folding each of the top 51, bottom 52, body 53, fill spout 57, and discharge tube 58 is fully automated and accomplished via machinery and/or robots. In various embodiments, one or more of the steps of folding each of the top 51, bottom 52, body 53, fill spout 57, and discharge tube 58 is done manually while one or more of the steps is accomplished through automation, e.g., with machinery and/or robots.
In various embodiments, each step of forming fusion or sealing areas 65, 66, 67, 68 is done manually. In various embodiments, each step of forming fusion areas 65, 66, 67, 68 is fully automated, e.g., accomplished via machinery and/or robots. In various embodiments, one or more of the steps of forming fusion areas 65, 66, 67, 68 is done manually while one or more of the steps of forming fusion areas 65, 66, 67, 68 is accomplished through automation, e.g., with machinery and/or robots.
In various embodiments, each step of forming joints 126, 127, 128, 129 is done manually. In various embodiments, each step of forming joints 126, 127, 128, 129 is fully automated, e.g., accomplished via machines. In various embodiments, one or more of the steps of forming joints 126, 127, 128, 129 is done manually while one or more of the steps of forming joints 126, 127, 128, 129 is accomplished through automation, e.g., with machinery.
In various embodiments, each of the folding steps, formation of heat fusion or sealing areas, and heat sealing to form joints is done manually. In other embodiments, each of the folding steps, formation of heat fusion areas, and heat sealing to form joints is fully automated. In yet other embodiments one or more of the folding steps, formation of heat fusion areas, and heat sealing to form joints is done manually, and one or more of the folding steps, formation of heat fusion areas, and heat sealing to form joints is automated.
In one or more preferred embodiments, a bottom flap or bottom cover 61 is included on bag 50 to provide further support for the bottom of a bag 50, and to help prevent sifting or leaking of bulk material from the bottom of a bag 50 (see
In a preferred embodiment, bag 50 includes a bottom flap or cover 61 providing additional support to bag 50. Bottom flap or cover 61 is also sometimes referred to herein as a diaper. Bottom cover 61 preferably extends from opposing sides of bag 50 across bottom 107 of bag 50, e.g., extending from a first side 162, across a width of bottom 52, over discharge tube 58, and to a second side 163. Alternatively, diaper 61 could extend from front side 165 to back side 166 across a width of bottom 52, and over discharge tube 58.
Cover 61 can have a fold 105 at the location where it extends from bottom 52 over joint 128 to one side, e.g., side 165 (see
Discharge tube 58 preferably is covered by cover 61. Cover 61 can therefore also help prevent any sifting or leaking of contents from discharge tube 58 of bag 50.
Testing has shown increased bag strength of over 50% percent when a cover 61 is attached to bag 50 with a shorter width between folds 105 and 106 than the width of the bag bottom. A rolled discharge tube assembly 63 with a cover 61 having a distance between cover 61 folds 105 and 106 that is about equal to the distance between two opposing bottom edges of a bag 50 passed the required 5 to 1 safety ratio tests. A discharge tube assembly that is pinch closed, however, as depicted in
In the FIBC/bulk bag industry, based on the 5 to 1 safety ratio requirements, a bag that will be carrying 2,000 pounds (907 kilograms) of material, for example, must pass testing with 10,000 pounds (4536 kilograms) of pressure applied, before the bag breaks. To test the bag, the bag is hung from its lift loops and hydraulic pressure is applied from a top of the bag to measure the force needed to break the bag.
In testing, a bag designed to hold 2,000 pounds (907 kilograms) of bulk material and having a heat fused discharge tube and bottom, and a rolled discharge tube or pinched tube in a closed configuration failed when applying 7,000 pounds (3,175 kilograms) of pressure to the bag. When a cover 61 was added to form a discharge assembly having a rolled or pinched closed configuration, the bag designed to hold 2,000 pounds (907 kilograms) of bulk material with a heat fused joint connecting a discharge tube and bottom was able to withstand 13,000 pounds (5897 kilograms) of pressure applied to the bag during testing. A cover 61 can thus increase the strength of the bag by over 50%.
Reference is made to U.S. patent application Ser. No. 15/345,452, filed on Nov. 7, 2016, titled, INDUSTRIAL BAG DISCHARGE SPOUT, incorporated herein by reference thereto, for additional information on discharge tube assemblies and bottom covers that can be used with a bag 50.
As discussed with earlier embodiments, heat fused joints of bag 50 preferably are formed by applying heat below the melting point of the fabric of the bag and low pressure, wherein preferably a fusion or bonding coating 191 comprising propylene based elastomers and plastomers, e.g., VERSIFY™ 3000, is on one side of the fabric to be joined in the fusion area, and a standard industry coating 192 is on one side of the other piece of fabric to be joined in a fusion area, wherein the standard coating 192 and fusion coating 191 are in contact with another so that when heat is applied to melt the standard and fusion coatings, a bond between the standard and fusion coatings is formed to establish the bag joint.
As discussed, a standard industry coating for polypropylene fabrics, which is sometimes referred to herein as a standard coating, generally comprises a majority percentage of polypropylene and a small percentage of polyethylene. Preferably, a standard polypropylene fabric coating used with one or more embodiments of the present invention has about 70-85 percent polypropylene with a balance of polyethylene, i.e., 15 to 30 percent polyethylene. More preferably, a standard polypropylene coating used in various embodiments of the present invention has about 70-85 percent polypropylene, with a balance of polyethylene and some UV inhibitors, and other additives.
For prior art bulk bags, generally a standard coating is applied at about 1 mil (0.03 millimeters) thickness. Preferably for a stitchless bag of the present invention a standard coating is applied at about 2.5 mil (0.064 millimeters) thickness. A standard coating can also be applied at about 1 to 2.5 mil (0.03 to 0.064 millimeters) thickness or over about 2.5 mil (0.064 millimeters) thickness.
Preferably a fusion coating is also applied at about 2.5 mil (0.064 millimeters) thickness. In other embodiments a fusion coating can be applied at about 1 to 2.5 mil (0.03 to 0.064 millimeters) thickness or over about 2.5 mil (0.064 millimeters) thickness. Given the high cost of a fusion coating, preferably a fusion coating is not applied above about 2.5 mil (0.064 millimeters) thickness, although it can be applied at a greater thickness.
In various embodiments, a coating on a particular bag portion, e.g., on a fill spout, top, body, bottom or discharge tube, can be applied at one thickness, while a coating on another bag portion can be applied at a different thickness. In various embodiments, a standard polypropylene fabric coating on one bag portion e.g., on a fill spout, top, body, bottom or discharge tube, can be applied at one thickness, while a standard polypropylene fabric coating on another bag portion can be applied at a different thickness. In various embodiments, a bonding coating on one bag portion e.g., on a fill spout, top, body, bottom or discharge tube, can be applied at one thickness, while a bonding coating on another bag portion can be applied at a different thickness. In various embodiments, a propylene based plastomers or elastomers coating on one bag portion e.g., on a fill spout, top, body, bottom or discharge tube, can be applied at one thickness, while a propylene based plastomer or elastomer coating on another bag portion can be applied at a different thickness.
When viewed under an electron microscope the bond created between a bonding coating that included VERSIFY™ 3000 and a standard polypropylene fabric coating is millionths of an inch (2.54 cm) thick. Experimentation has shown that this bond is even stronger than a bond formed between two fabric pieces of fabric that each contain a VERSIFY™ 3000 coating. The bond between a VERSIFY™ 3000 coating and a standard coating is also preferred given lower cost as each fabric piece does not need the more expensive VERSIFY™ 3000 coating. In one or more preferred embodiments, only fill spout, body, and discharge tube fabric pieces, have a bonding coating, e.g., VERSIFY™ 3000, whereas the remainder of the bag fabric can have a less expensive polypropylene standard industry fabric coating that only acts as a heat sealing coating to form a bag joint in a fusion or heat sealing area when in contact with a bonding coating. In one or more preferred embodiments, only top and bottom portions of a bag have a bonding coating, e.g., VERSIFY™ 3000, whereas the remainder of the bag fabric can have a less expensive polypropylene standard industry coating that only acts as a heat sealing coating to form a bag joint in a fusion or heat sealing area when in contact with a bonding coating.
Experimentation has established that (1) heat applied to highly oriented polypropylene fabric pieces with standard coating to standard coating in a fusion area does not create a joint that can hold even low weights; (2) heat applied to highly oriented polypropylene fabric pieces with a standard coating to a fusion coating in a fusion area creates a very strong joint; (3) heat applied to highly oriented polypropylene fabric pieces with fusion coating to fusion coating in a fusion area creates a strong joint.
Another advantage of forming a joint with a bond between bonding and standard coatings is that the majority of fabric, e.g., on the body, discharge and fill spouts, can have standard coating on the exterior. Only where a standard and bonding coating overlap will a seal be formed when applying heat. This is important in bag formation because if a heating bar is misapplied, the bag will not be destroyed flawed by unwanted joints or connections. If a bonding coating is on the exterior surface of the body, discharge tube and fill spout, and also on the interior surface of the bottom and top, a fusion heat seal will be formed between two pieces of fabric wherever the heat is applied, and if the bar is not aligned right, or the pieces are not aligned right in the fusion area, unwanted joints and seals can be formed that interfere with the bag integrity or usefulness.
With the bag configuration as shown in
In other embodiments, the coatings can be switched, e.g., a fusion coating 191 can be on the exterior surfaces of the fill spout, body, and discharge tube fabrics and a standard coating 192 on the interior surface of the top and bottom fabrics. However, this is less cost effective as more bonding coating on the fabric will be utilized. In a preferred embodiment only top and bottom fabric layers have a more expensive bonding coating whereas other portions can have less expensive standard fabric coatings on each fabric layer. As discussed with earlier embodiments, a fusion coating 191 can also be provided as the only heat sealing coating provided on the fabric layers.
It is also possible to use fabrics with a fusion coating on both interior of top of and bottom portions and exterior sides of body, fill spout and discharge tube portions. However, preferably a standard coating is fused with a bonding coating in all fusion areas to not only form a stronger bond but also to be more cost effective. When a standard coating is fused with a bonding coating it helps prevent total loss of a bulk bag, given misalignment for example of a heating element because only the portion containing a bonding coating where heat is applied will be heat sealed to form a joint. Any portions with heat applied on the standard coating to standard coating will not form a bag joint or permanent bond or create fused areas in non-designated fusion or sealing areas.
In various embodiments, a lift loop assembly 56 can be heat sealed to a bag 50 (see
Reference is made to U.S. patent application Ser. No. 15/383,841, filed on 19 Dec. 2016. titled INDUSTRIAL BAG LIFT LOOP ASSEMBLY, by the same inventors and incorporated herein by reference thereto, for additional information on a lift loop assembly that can be used with a bag 50.
Turning to
The taping configuration, for example, can be beneficial in embodiments of a heat fused bag wherein a bottom portion opening 78 is constructed with four slits. In this configuration, a zero point area can occur at the 90 degree angle point in the slit area, wherein two portions of fabric are at 90 degrees respective to each other, going from the horizontal to the vertical, at the bottom portion slit areas, which are weak areas in a heat sealed bag. Taping configurations as described herein can overcome the weak area at the zero point.
In other embodiments, the taping configuration may not be needed, e.g., when a discharge tube in gusseted form is positioned through the bottom opening 78 and sealed to the bottom flaps wherein the slit between bottom flaps is not located at or near a corner of the gusseted discharge tube in folded and flattened configuration. For example, the discharge tube and bottom flaps can be fused together wherein the bottom slits are located at or about centrally between the corners of the discharge tube in folded and gusseted form. When sealed in this manner, the weak areas do not result in a blowout point for the bag, e.g., when heavier contents are included therein. A taping configuration as shown in the figures, however, can still be used in this embodiment if desired for providing additional reinforcement to the joint connecting the discharge tube and bottom
If including a tape configuration as shown in
In other embodiments, the tape configuration can be applied after forming a joint 129 between a discharge tube 58 and bottom portion 52, possibly before completing other bag joints.
This tape configuration preferably is applied to both corners at the bottom of the bag when lying flat in folded gusseted form. The same tape configuration as illustrated in
As previously mentioned, in some embodiments a bonding or standard coating is applied to the tubular fabric portions when the tubes are flattened, with the coating extending beyond the folded edge or close to the folded edge or over tape applied on the folded edge. When forming heat sealing or fusion areas, the said folded edge of a discharge tube portion or a body portion for example can be positioned about centrally so that a diaper cover will cover the said folded edge portion when it is applied to the bag, as shown in
After positioning each piece of tape, pressure can be applied to couple the tape to the bag. Pressure can be applied via the machinery as shown in
A zero point tape press assembly 260 as shown in
Table 261 can include a frame 271 with four legs 281. A lower bracket support 263 can be used to couple press bar assembly 262 to table 261, e.g., with a bolt 264, washer 265, nut 266 as shown in
In one or more embodiments, a table used with one or more of the machine assemblies as shown and/or described herein can be assembled by selecting a first table portion to be coupled to another table portion. In one or more embodiments, a table used with one or more of the machine assemblies as shown and/or described herein can be assembled by selecting a first table end portion, one or more middle portions, and another table end portion. Selected end portions can be coupled together at splice plate locations, e.g., at splice plate 274 as shown in
A table 261 height can preferably be about 34.50 inches (87.6 cm). A table 261 can also have other desired heights. A table top 278 can have a portion 279 that extends a distance past frame 271, e.g., about 1 inch (2.54 cm) past frame 271 on each side of frame 271. In other embodiments, a portion 279 does not need to be included, or portion 279 can have another desired dimensions.
A frame 271 can include legs 281. Each leg 281 can have a base pad 282 (see
In a preferred embodiment, an end of frame 271 can be about 66 inches (167.6 cm) long. Front and back sides of a frame 271 can be about 84 inches (213.4 cm) long. The distance between a cross member 283 on a loop impulse sealer side to a first mid-brace member 285 can be about 42 inches (106.7 cm). The distance from a cross member 283 on loop impulse sealer side to a second mid brace member 285 can be about 66 inches (167.6 cm). The distance between the location where a corner brace 286 is coupled to a leg 281 and to the top of the frame 271 can be about 13 inches (33 cm). Other desired dimensions can also be used for a frame 271 and its parts.
One spacer 373 can be coupled between cross supports 271 at an upper location on cross supports 271, with cross supports 271 coupled between left longitudinal supports 374 on a left side of cross supports 271 with a thread rod 377, washers 378 and cap nuts 379, for example, as shown in
Cylinder mount bracket 372 can be coupled between cross supports 271 on a lower location of cross supports 371 with thread rods 377, washers 378 and cap nuts 379 as shown in
One bottom bracket 376 can be coupled between left longitudinal supports 374 at a bottom location of left longitudinal supports via two thread rods 377 and washers and cap nuts as shown in
Pneumatic cylinders 352 can be coupled to cylinder mount bracket 372 of taping press sub-assembly 351 with cap screws 353, for example, and with ends 364 of pneumatic cylinders extending through openings 365 of cylinder mount bracket 372. Clevises 354 can be used to couple cylinders 353 to the seal bar or press block 363. For example, two clevises 354 can receive ends 364 of cylinders at top opening 375 of clevises 354. Clevises 354 can also be coupled to sealing bar or block 363, for example with positioning brackets 358, 359, shafts 355, shaft collars 357, flat washers 356, thread rods 360, washers 361, and cap nuts 362, as shown in
Preferably a pair of positioning brackets 358 each has an opening 693 sized to receive a shaft 355 and to allow for little or no movement of shaft 355. Preferably a pair of positioning brackets 359 has an opening that is larger than the opening of brackets 358, and can be a slotted opening 694, for example. With this configuration, when lowering the press block 363 to make contact with the fabric, brackets 693 hold press block 363 in a substantially fixed position over the bag and tape to be pressed, while slotted brackets 694 enable a left to right rocking motion of the press block. The rocking motion can help ensure even pressure is applied even in areas where the fabric of the bag or tape has different densities. Preferably slotted openings are not included in each positioning bracket 358 to 359 because this could then allow for the press block to not stay in a substantially fixed position over the bag and tape configuration.
After arranging tape 71a, 71b, and 72 on a bag 50, the bag 50 can be placed on table portion 278 with the tape configuration under seal bar or press block 363. Cylinders 352 can lower block 363 onto the tape configuration to apply pressure and effect connection of the tape 71a, 71b, 72 to bag 50.
Referring to
The left section 475 of table top 479, can include bottom cover heat sealer assembly 398 with an opening 392. Heat sealer assembly 398 can include lower 388 heat seal assembly and upper 387 mating heat sealing assembly. Lower assembly 388 can be positioned below opening 392. Upper assembly 387 can be positioned above opening 392. Both upper 387 and lower 388 assemblies of bottom cover assembly 398 can include a heat seal bar assembly 434 as shown in exploded view in
The middle section 476 of table top 479 can include a document pouch heat sealer assembly 399 with heat sealer sub-assembly 393 and insulation pad 397 centered below. Right section 472 of table top 479 can be provided to increase a length of table assembly 381 as needed, or to provide a table top portion for assembling or holding bag parts or portions.
As shown in
In a preferred embodiment, a frame 471 end side can be about 66 inches (167.6 cm) long. Front and back sides of a frame 471 can be about 110 inches (279.4 cm) long. The distance between left side end cross member 483 and a first cross member 487, can be about 24 inches (61 cm). The distance between left side end cross member 483 and a second cross member 487, can be about 30 inches (76.2 cm). Measuring from a cross member 483 on left side 475 to a third cross member 487 can be about 38 inches (96.5 cm). The distance between left side end cross member 483 and a third cross member 487, can be a distance of about 49 inches (124 cm). The distance between left side end cross member 483 and a fourth cross member 487, can be about 16 inches (40.6 cm). The distance between the location where a corner brace 485 is coupled to a leg 481 and to the top of the frame 471 can be about 16 inches (40.6 cm). Other desired dimensions can also be used for a frame 471, e.g., to accommodate a bag and its respective parts to be heat sealed.
A heat sealer frame assembly 383 is shown in
Heat seal bar assembly 541 can be coupled to cylinders 492 with clevises 394, shafts 395, shaft collars 16, seal bar position brackets 545, slotted seal bar position brackets 546, thread rods 542, washers 543 and nuts 544, as shown in
Preferably a pair of positioning brackets 545 each has an opening 572 sized to receive a shaft and to allow for little or no movement of the shaft. Preferably a pair of positioning brackets 546 has an opening that is larger than the opening of brackets 545, and can be a slotted opening 573, for example. With this configuration, when lowering the upper heat sealing bar assembly 541 to make contact with the fabric in the joint area, brackets 545 hold press block in a substantially fixed position over the bag pressed, while slotted brackets 546 enable a left to right rocking motion of the sealing bar. The rocking motion can help ensure even pressure is applied while heating through all layers of the joint area, even in areas where the fabric of the bag has different densities. Preferably slotted openings are not included in each positioning bracket 545, 546 because this could then allow for the sealing bar to not stay in a substantially fixed position over the bag when heat sealing the joint.
A bottom cover heat sealing assembly 434, which can be used in upper and lower heat sealing assemblies 387 and 388 is shown in
In
When attaching a bottom cover 61, after positioning the cover 61 on a bag 50, the bag 50 can be positioned on table 479 with the desired joint area for the document cover positioned over opening 392. Cylinders 492 can lower heat seal bar assembly 541 to make contact with the document cover 61 on the upper side of the bag 50, which can mate with lower heat seal bar portion 388 which can be in contact with the bottom cover 61 on the backside of bag 50. In the embodiment as shown, lower heat seal bar portion 388 is not raised or lowered. The dimensions of cover heat assembly 398 can define the dimension of a bottom cover joint on both front and backsides of bag 50. Preferably the joint begins below cover pull tab or flap 64 of cover 61 so that tab or flap 64 is not coupled to bag 50 and can be pulled to release cover 61 from the bag 50 when discharging contents of bag 50.
Similarly, a heat sealer machine 630 can be used to form joints between a bag body 53 and bottom 52, and between a bottom 52 and discharge tube or spout. In various embodiments, bottom 52 in 2D, folded or gusseted configuration can be manually overlapped, for example, with body 53 to form fusion area 67. Bottom 52 can be temporarily attached to the bag body 53 in 2D configuration, e.g., with removable tape. Discharge tube 58 in 2D configuration can also be manually overlapped with bottom 52 to form fusion area 68 and be non-permanently attached to bottom 52, e.g., with removable tape. Each fusion area 67 and 68 is can be positioned under a heat sealing bar of the heat sealing machine 630.
A spout/top/body/bottom/tube heat sealing assembly 630 can include a table assembly 631 with a spout/tube to top/bottom heat sealing portion 645 and a top/bottom to body heat sealing portion 646. Spout/tube to top/bottom heat sealing portion 645 can be coupled to table assembly 631 with heat sealing frame 632, lower bracket support 642 and nuts 635, washers 636, 643 and screws 637, 644 as shown in
Spout/tube to top/bottom heat sealing portion 645, can include upper heat sealer assembly 633 and mating lower heat sealer assembly 638. Lower assembly 638 can be positioned below opening 648. Upper assembly 633 can be positioned above opening 648.
Top-bottom to body heat sealing portion 646, can include upper heat sealer assembly 640 and mating lower heat sealer assembly 641. Lower assembly 641 can be positioned below opening 649 in table top 647. Upper assembly 640 can be positioned above opening 649 in table top 647.
Frame 651 can have transverse end cross members 663 coupled to front and back cross members 664 along an outer perimeter of the table frame 651. Additional internal front and back cross members 666 can be included on an interior side of front and back cross members 664. Cross members 666 can also be coupled to end cross members 663 and spaced a distance away from front and back cross members 664, e.g., about 4 to 6 inches (10.2 to 15.2 cm) away. Internal transverse cross members 667 can extend between and be coupled to cross members 666 on the left side 652 and middle 653 of frame 651. Four cross members 667 for example on be on left side 652 of frame 651. One cross member 667 for example can be in the middle section of frame 652. Corner braces 665 can also be included on frame 651, extending from a leg 661 to an end cross member 663 or a front or back cross member 664.
In a preferred embodiment, a frame 651 end side can be about 66 inches (167.6 cm) long. Front and back sides of a frame 651 can be about 110 inches (279.4 cm) long. The distance between left side end cross member 663 and a first cross member 667, can be about 16 inches (40.64 cm). The distance between left side end cross member 663 and a second cross member 667, can be about 24 inches (61 cm). The distance between left side end cross member 663 and a third cross member 667, can be about 30 inches (76.2 cm). The distance between left side end cross member 663 and a fourth cross member 667, can be about 38 inches (96.5 cm). The distance between left side end cross member 663 and a fifth cross member 667, can be about 49 inches (124.5 cm). The distance between where a corner brace 665 is attached to a leg 661 and the top of the frame 651 can be about 16 inches (40.6 cm). Other desired dimensions can also be used for a frame 651 and its parts.
Referring to
A spout/tube to top/bottom heat sealing assembly 645 can also include a lower heat sealing assembly 638, with a heat seal bar assembly 687, a preferred embodiment of which is shown in exploded view in
Heat seal bar assembly 687 can include a main body 731, heat insulating pad 732, preferably a single piece heating element 733, and lower bracket support heat strip tension sub-assemblies 734 on each end of main body 731. A heat strip tension sub-assembly 734 can be coupled to a main body end 731. Ends of the heating element 733 can be positioned between heat strip mounting ends 735. A heat strip retaining cap 736 can be positioned at ends of the assembly 687. Preferably retaining cap 736 is reusable, e.g., if heating element 733 needs to be replaced.
An assembly 687 can be coupled together with pins 743, 744, button head socket cap screws 740, and tee nut inserts for wood 748. Springs also are preferably included and positioned through two holes of heat strip sub assembly 584, as shown in
In various embodiments, a heat strip sub-assembly, e.g., heat strip sub assembly 584, holds tension springs in the two larger holes and keeps tension on heating element 583.
A heat seal bar 687 can also include stand off block 737, washers 738, wire tire wraps 739, button head socket cap screw 742, flat head cap screws 741, pin 743, PTFE coated cloth tape 746 and 747, and tee nut inserts for wood 748, as shown in
Heat strip tension sub-assembly 734 can be the same as, or similar to, the tension sub-assembly depicted in
Referring to
A spout/tube to top/bottom heat sealing assembly 645 can also include a lower heat sealing assembly 641 including a seal bar assembly 751, a preferred embodiment of which is shown in exploded view in
Each end of a main body 761 can include a lower bracket support heat strip tension assembly 764, which can be the same or similar to the tension sub-assembly depicted in
A heat strip sub-assembly 764 can be coupled to a main body end with heat strip mounting ends 765, a heat strip retaining cap 766, compression springs 776, tee nut inserts for wood 778, pin 773,774, and screws 770, which can be button head socket cap screws. Preferably a cloth tape 777, e.g., PTFE coated cloth tape, is positioned on top of an angled portion of heat strip mounting end 765 when coupled to main body 761. A heat insulating pad 769 can be placed on top of main body 761. Heating element 768 can be placed on top of heat insulating pad 769 and can have an angled portion that corresponds to the location of the PTFE coated cloth tape 777 on a heat strip mounting end 765. Ends of heating element 768 can be coupled between mounting ends 765 as shown in
Preferably at least one of the mating heat sealing bar assemblies used in one or more embodiments of a heat sealing machine has a rocking motion during the heat sealing process which helps form a complete and even seal for all fabric layers in a fusion area. A rocking motion can be effected by a pivot yoke axis that enables rotation of a pin along a pin axis as described further herein with regard to
A bracket including a slotted opening e.g., brackets 613, can enable a rocking motion of a seal bar assembly. When a pin or shaft goes through the slotted opening and through the cylinder yoke, the slotted opening allows the assembly to self-adjust on the fabric with multiple layers of fabric that can be uneven. With the rocking motion, even where the fabric is uneven, an equal pressure is applied to all the fabric in the joint area. The rocking motion allows the upper and lower heat sealing assemblies to mate in a perfectly parallel, or almost perfectly parallel fashion.
If equal pressure is not applied, in higher areas of the fabrics hot spots or bright spots or shiny spots can develop during heat sealing, where those higher areas start to melt or the heat starts to damage to the fabric. If each positioning bar had a circular opening similar to that of positioning brackets 682, which is preferably sized to receive a shaft 688, for example, but to allow little or no movement of shaft 688 during heat sealing, when the heat seal bar came down at different levels it would bind up and hit the surface unevenly and would not rock and self-adjust or self-align. With the slotted opening, as an angle increases when coming down on a mismatched area, the slotted bar allows for the rocking and self-adjusted so binding up of the seal bar does not occur.
In the embodiments of heat sealing assemblies as shown in the drawings, the upper heat sealing assemblies have a rocking motion, while the mating lower heat sealing assemblies do not have a rocking motion and remain stationary.
In a preferred embodiment the heating bar has two pivot points. A first pivot point can preferably be set to no rocking, e.g., wherein the pivot point holds the seal bar in a substantially horizontal fixed position. A second pivot point preferably includes a slot which enables the desired rocking motion and rotation of the pin at the first pivot point that is set to no rocking and holds the seal bar in the fixed horizontal location.
A sealing bar that can be used in one or more embodiments of the present invention also preferably has reusable end caps, e.g., end caps 586 and 736 as shown in
Preferably one or more embodiments of a heat sealing machine that can be utilized in the present invention can control temperature, length of heating and pressure applied in a heat sealing or fusion area. Preferably a heat sealing machine also has at least a double sensor fail safe. A first sensor can monitor temperature, pressure and time. A second sensor can monitor the first sensor.
The use of impulse heating helps to prevent crystallization of the fabric. The temperature is preferably held within a desired range, e.g., about a 5 degree range, or a about 5 to 10 degree range. If the temperature varies more than the desired range, e.g., more than about 10 degrees, the machine can be set to automatically shut off. An acceptable range for the temperature during heat sealing a joint can be programmed for a given machine, and if the temperature moves outside of the acceptable range the machine can be set to automatically shut off. For a heat sealing machine that seals more than one joint, the machine can be set to include parameters for temperature, time and pressure for heat sealing one particular joint, and can be set to include different, or the same, parameters for temperature, time, and pressure for heat sealing another joint. Having different parameters for different bag joints may be desired given the size of the joint area, the number of layers in the joint area, and/or if fabric pieces of one joint area have different densities than fabric pieces of another joint area.
Preferably the amount of time a heat seal bar or heat seal bar assembly is held over a heat fusion area for a spout to top, top to body, body to bottom or bottom to tube joint is long enough to heat through 8 layers of fabric, e.g., per the gusseting and 2-dimensional folded configurations previously described, without damaging the fabric itself. The time can be held per preferred testing values, so that a machine can heat seal area through each fabric area in the fusion area, e.g., 8 layers of fabric, at one time.
A heat sealing bar or heat sealing bar assembly that can be used in one or more embodiments of a heat sealing machine preferably are sized to extend a distance beyond the desired fusion area, e.g., a heat sealing bar can extend about ½ to 2½ inches (1.27 to 6.35 cm) on either side of a fusion area. This enables formation of non-graspable edge to the joints so that the fabric near the joint edge cannot be pulled or caught on something, wherein no fabric is left unsealed that could be grasped and pulled. The heat sealing bar extending beyond the fusion area can also ensure no leakage at the joint and an airtight seal. Note in one or more preferred embodiments when a fusion area includes a standard fabric coating and a bonding coating, because the fusion coating is only in contact with standard coating in the fusion area, even when the heat seal bar extends beyond the fusion area, the joint formed does not extend pass the desired fusion area given that beyond the fusion area only standard to standard coatings are in contact when under the heat seal bar.
Preferably each joint formed in a stitchless bag 50 is in a shear direction when a bag 50 is standing upright and ready to be filled, or is filled with bulk material. Preferably, fabric to be joined via heat sealing has a standard industry fabric coating in contact with a standard industry fabric coating in areas that extend beyond a desired seal or fusion area, and the heat bar can extend beyond the seal area to ensure no leakage and provide non-graspable edges of a heat sealed joint.
In one or more embodiments a triangular shaped edge can also be formed on a bag 50, e.g., at corners of the bag when upright, that will also help prevent leakage (see, e.g.,
For example, in one or more embodiments, the top and bottom portions of a bag can be sized so that when coupled to the bag body a portion of the top and bottom will extend a distance beyond the bag body on each side of the bag body, and this portion that extends beyond the bag body can be a generally triangular shape given the gusseted and folded position of the bag bottom and top portions (see
In
Loop heat sealing assembly 782, can include left and right heat sealer assemblies 795 and 796. Left heat sealer assembly 795 can include left upper heat sealer subassembly 785 and mating left lower heat sealer subassembly 786. Left lower heat sealer subassembly 786 can be positioned below opening 809. Left upper heat sealer assembly 785 can be positioned above opening 809. Right heat sealer assembly 796 can include right upper heat sealer subassembly 783 and mating right lower heat sealer subassembly 787. Right lower heat sealer subassembly 787 can be positioned below opening 810. Right upper heat sealer assembly 783 can be positioned above opening 810.
Table frame 801 can have transverse end cross members 813 coupled to front and back cross members 814a along an outer perimeter of the table frame 801. Additional internal front and back cross members 814b can be included on an interior side of front and back cross members 814a. Cross members 814b can also be coupled to end cross members 813 and spaced a distance away from front and back cross members 814a, e.g., about 4 to 6 inches (10.2 to 15.2 cm) away. Internal transverse cross members 816 can also be included and extend between and be coupled to cross members 814b on the left side 802 of frame 801. Corner braces 815 can also be included on frame 801, extending from a leg 811 to an end cross member 813 or from a leg 811 to a front or back cross member 814a.
In a preferred embodiment, a frame 801 end side can be about 66 inches (167.64 cm) long. Front and back sides of a frame 651 can be about 84 inches (213.4 cm) long. The distance between a right side end cross member 813 and a first cross member 816, can be about 42 inches (106.7 cm). The distance between a right side end cross member 813 and a second cross member 816, can be about 66 inches (167.6 cm). The distance between where a corner brace 665 is attached to a leg 811 and the top of the frame 801 can be about 16 inches (40.6 cm). Other desired dimensions can also be used for a frame 801 and its parts.
Two pairs of cylinders 823 can be provided. Each pair of cylinders 823 can be coupled to cylinder mount 822 using hex head screws 828, washers 825, nut 827, flat head socket screws 824, for example. The pairs of cylinders 823 can be coupled to cylinder bracket 833 of frame assembly 829.
Referring to
Right lower heat sealer subassembly 787 can also include left heat seal bar assembly 841 and brackets 797 as shown in
An embodiment of a left heat seal bar assembly 841 that can be used with right heat sealer assembly 796 is shown in
A left heat seal bar assembly 841 as shown in
As shown in
A heat seal bar assembly 883, 884, 885 and/or 886 can have the same or similar structure as a heat seal bar assembly shown and described with regard to
Regarding
After a fabric portion is fed to the gusseting portion, two more seals can be made in the fabric. A novel feature of the machine includes a hinge without a bolt, wherein it pivots on an infinite center point (a zero point pivot). After additional seals are made, gussets in the body can be formed manually or automated, wherein the two newly sealed areas are pulled internally towards the center, e.g. sides 163, 164 of body 53.
The fabric is then preferably fed through a portion of the gusseting machine that is bifurcated (has double motion) to push the fabric materials to center and line them up, the fabric can go through a rolling motion, which is an important novel feature because such a rolling motion helps ensures the gussets in the fabric line up perfectly without touching. Without the rolling motion, the fabric would not line up perfectly, and misplacements or touching of the gussets of the interior surfaces of gusseted portions could occur, which can result in formation of unwanted seals during the heat sealing process.
After gussets are lined up, preferably fabric and gussets are pressed to lie flat by the press part of the machinery.
Additional machinery that can be used in the method of the present invention are top/bottom die press machinery, which can cut the bottom and top fabric portions of the bag. Preferably the top and bottom are die cut for extreme accuracy. e.g., within about 1/16 of an inch (0.16 cm) of accuracy.
Top/bottom portion gusseting machines may also be provided. Preferably the top and bottom of the bag fabric portions comprise the same dimensions. Gussets in top and bottom portions can be manually folded, or folded via machinery and then brought to other heat sealing machinery, either manually or by a conveyor for example, to form joints with a body and or fill or discharge tube.
Preferably the method includes a final quality check step, wherein a stitchless bag 50 is checked for any burn marks, which can be indicative of fabric damage; for proper tape configuration; that all joints have an air tight seal, and that there are no lips.
In various embodiments different machines can be provided to make bags of varying widths. Preferably the length of a bag at any given width can be adjusted with use of any given machine.
Preferably a stitchless bag of the present invention is food safe without any sifting holes.
Preferably a stitchless bag of the present invention eliminates the need for a liner within the bag, e.g., a polyethylene liner.
One or more preferred embodiments of the method of the present invention enable minimal amounts of fabric to create a bag 50 because it does not requiring extra fabric to form a seam as is done in sewn bags. The joint formation also does not involve folding over of fabric, e.g. from a front side over an edge to a back side, to form a joint area, which reduces use of fabric as well.
Turning now to
As part of the system and method, first fabric pieces for respective bag portions, e.g., fabric pieces for a fill tube, top, body, bottom and discharge tube, are prepared in substantially flat, folded (2-D) construction, which in turn allows for automation and precision (e.g., within =/− about 1/16 inch (0.16 cm)) in the FIBC manufacturing.
The automated system enables production of bulk bags with no manufacturing equipment/tools being inside the bag, or on interior surfaces of the bag, during manufacturing.
Heat sealing machinery preferably includes two and three axes impulse heat sealing heads which allow full self-alignment and full self-adjusting during the heat sealing process.
Preferably single piece heating elements are utilized which have lower costs and lower maintenance change-over time.
Preferably dual fail-safe sensor controls are provided over the set temperature points, which provides another quality check.
A multiple purpose carrier tray system is preferably used for (a) parts assembly, (b) tooling set-up and (c) quality checks of parts during assembly.
In the embodiment as illustrated in
Preferably the folded bag portions on a cart 450 are pre-marked to designate overlap locations or specifications to help assemble a bag on a carrier plate 200 with overlapped locations for forming fusion areas or other heat sealing areas on a bulk bag. For example, a discharge tube 58 can have a mark at the desired width of the overlap area of discharge tube 58 and bottom 52. Bottom 52 likewise can have a mark to designate the desired overlap area for the fusion joint area to be formed with discharge tube 58 and bottom 52. Similarly a bag body 53 can have a mark to designate where it should overlap with a top 51 and a mark to designate where it should overlap with a bottom 52. Body 53 can also have one or more marks to designate where a document pouch 73 should be placed on body 53. Body 53 can also have one or more marks to designate how and/or where lift loop assemblies 56 and a diaper or cover 61 should be positioned on the body 53 while on a carrier plate 200.
In other embodiments lasers as part of the machinery can be utilized to designate how bag portions should be assembled, either alone or also in conjunction with markings on the bag portions. Other suitable means known in the art can also be used to help designate overlap areas or joint areas between bag fabric portions and other bag parts.
In various embodiments, more than one carrier plate 200 can be provided as part of the method, e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, and/or more carrier plates 200 provided so that more than one bag can be assembled and heat sealed in sequence.
Preferably a cart 450 is designed to be unloaded from any side. Preferably at least one or more of the folded and gusseted bag fabric portions on the cart 450 include a coated side with a bonding coating so that when fusion areas are formed on the carrier plate, as discussed further below, at least one of the fabric pieces in at least one fusion area has a bonding coating. The other fabric piece in the said fusion area can have either a bonding coating or a standard fabric laminate coating.
In some embodiments, a bag can be formed with only one heat fused joint.
In other embodiments, a bag can be formed with more than one heat fused joint.
In preferred embodiments, a bag is formed with all heat fused joints, at least in a containment area of the bag.
In some embodiments, a first station in an automated production line can be form forming one heat fused joint for a bag.
In other embodiments, a first station in an automated production line can be for forming more than one heat fused joint.
In preferred embodiments, a first step in an automated production line can be for forming at least 4 heat sealed main bag body joints at one time.
In
In other embodiments, cage rods 454 could also be arranged differently to accommodate other desired arrangements or sequence of the bag fabric pieces. Preferably such a cart 450 will hold all the bag fabric pieces that will be heat-sealed by the respective heat sealing machine in the sequence of the automation process for at least a day's work.
The bag fabric pieces held on cart 450 can be assembled by an operator on a carrier plate 200, which is shown on top of a main body assembly table 250 in
Referring to
As mentioned earlier, a carrier plate 200 or 1300 can serve as a (a) precision parts assembly platform, (b) tooling plate for machine set-up and (c) material quality check during assembly. A carrier plate can be constructed based on desired bag dimensions, and desired bag portion or parts assembly. A heat sealing machine can be constructed based on the carrier plate dimensions. A carrier plate 1300, including example dimensions in
A carrier plate 200 can include spout guides 201 which can provide a quality check function; tooling location points 202 which can provide a quality check function; holding clamps 203; body guides or stiffening support 204 which can serve a quality check function; and top/bottom guides 205, which can serve a quality check function. Body guides or stiffening support 204 can be the side edges of the carrier plate
Preferably a carrier plate 200 includes three spout guides 201 for guiding placement of a fill spout 57 on a second end 255 of the carrier plate 200 and three spout guides 201 for aiding in placement of a discharge tube 58 at a first end 254 of the carrier plate 200. To guide proper placement of a fill tube 57 fabric portion on carrier plate 200, one spout guide 201 is preferably positioned laterally at second end 255 of the carrier plate 200 and two other spaced apart spout guides 201 are preferably positioned longitudinally on the carrier plate a distance away from the laterally positioned spout guide 201 at second end 255. An operator can place a fill tube 57 fabric piece on the carrier table so that upper portion 110 of the fill spout 57 makes contact with the lateral spout guide 201 at the second end 255 of carrier plate 200 and so that respective sides of the folded and gusseted fill spout 57 make contact with the respective longitudinal spout guides 201 at second end 255.
Likewise, for guiding the proper placement of a discharge tube 58 on carrier plate 200 one spout guide 201 is preferably positioned laterally at a first end 254 of carrier plate 200 and two other spaced apart spout guides 201 are preferably positioned longitudinally on the carrier plate 200 a distance away from the laterally positioned spout guide on first end portion 254. An operator can place a discharge tube fabric piece on the carrier plate 200 so that bottom portion 109 of the discharge tube 58 makes contact with the lateral spout guide 201 on the first end 454 and so that respective sides of the folded/gusseted discharge tube 58 make contact with respective longitudinal spout guides 201 on the first end 254.
Preferably the longitudinally placed spout guides 201 are spaced a distance away from one another on the carrier plate 200 to match the selected width of a discharge tube 58 and fill tube 57 for a bulk bag 700 that will be produced. In this manner the spout guides 201 act as a quality check for the fabric pieces and can provide an indication as to whether the fill and discharge tube fabric pieces are the proper dimensions for the bulk bag 700 to be manufactured. If the fill and discharge tubes do not make contact with the spout guides or if a width of the fill and discharge tubes extend beyond the spout guides 201, then this provides information as to whether the fabric pieces are under or oversized and whether they should be utilized in making the bulk bag 700.
The laterally placed spout guides 201 also provide a quality control function. The carrier plate 200 is preferably designed to hold an assembled bulk bag prior to heat sealing wherein the bag fabric pieces can be positioned on the carrier plate 200 and the overlapped desired fusion areas for the bag joints can be formed. If an operator positions the fill spout 57 and discharge tube 58 so that the bottom portion 109 of the discharge tube 58 is in contact with the lateral spout guide 201 at first end 254 and so that upper portion 110 of the fill tube 57 is in contact with the lateral spout guide 201 at second end 255, this helps ensures that the desired overlap locations, or fusion areas for bag joints will be properly aligned.
Top and bottom fabric portions guides 205 are also preferably provided on the carrier plate 200. Guides 205 on first end portion 254 of carrier plate 200 preferably are spaced away from each other and positioned on carrier plate 200 at an angle to match the narrow triangular shape and width of a bottom portion 52 in folded or gusseted form. An operator can position a bottom 52 end portion 103 between the guides 205 on first end portion 254 of carrier plate 200, with the respective sides of the bottom portion fabric piece making contact with the guides 205. Guides 205 on second end portion 255 of carrier plate 200 preferably are spaced away from each other and positioned at an angle to match the shape and width of the narrow triangular shape of top portion 51 in folded or gusseted form. An operator can position the narrow triangular portion 101 of a folded top 51 between the guides 205 on second end portion 255, with the respective sides of the top portion fabric piece making contact with the guides 205.
Guides 205 also provide quality check functions for the bottom 52 and top 51 fabric pieces. The guides 205 are preferably placed on the carrier plate 200 to match the width of the folded top and/or bottom triangular form starting at the narrow end of the folded triangular form. The guides 205 are also preferably positioned on the carrier plate 200 to guide the formation of fusion area 68 between the discharge tube 58 and bottom 52, and to guide formation of fusion area 65 between the fill spout 57 and top 51.
Preferably when the discharge tube 58 is positioned so that bottom portion 109 is in contact with the lateral spout guide 201 on first end 254 of carrier plate 200 and bottom 52 is positioned so that the narrow triangular portion 103 of the folded bottom 52 is in contact with the top most portion of the bottom guides 205, upper portion 177 of folded discharge tube 58 can be positioned through opening 78 of folded bottom 52. The carrier plate 200 guides 201 and 205 can help define the overlapped area between a fill spout and top, and between a discharge tube and bottom. When a top and fill spout of selected dimensions are positioned on the carrier plate between the respective guides, an overlap area will form and the overlap area that forms can be checked based on additional markings or lasers provided that can also designate desired dimensions of the overlap areas.
In a similar way, preferably when the fill spout 57 is positioned so that upper portion 110 is in contact with the lateral spout guide 201 on second end 255 of carrier plate 200 and top 51 is positioned so that the narrow triangular portion of the folded top 51 in contact with the top most portion of the top guides 205, lower portion 111 of folded fill spout 57 can be positioned through opening 76 of folded top 51. The carrier plate 200 guides 201 and 205 can help define the overlapped area between a fill spout and top, and between a discharge tube and bottom. When a top and fill spout of selected dimensions are positioned on the carrier plate between the respective guides, an overlap area will form and the overlap area that forms can be checked based on additional markings or lasers provided that can also designate desired dimensions of the overlap areas.
Body guides or stiffening support 204, can be sides of the carrier plate. An operator can position a body portion 53 between body guides or stiffening support 204 and center body portion 53 between top 51 and bottom 52 positioned on the carrier plate 200. The distance between body guides or stiffening support 204 preferable corresponds to the width of a body portion 53 to be included in bag 700. Body guides or stiffening support 204 also therefore provide a quality check function for the dimensions of a body portion 53 to be part of a bag 700.
Body portion 53 can also potentially be centered on carrier plate 200 between tooling locations 202 at the first 254 and second 255 ends of carrier plate 200. Upper portion 161 of body 53 can be placed at or about tooling location 202 on the second end 255 of carrier plate 200), and lower portion 162 of the folded body portion 53 can be place at or about the tooling location 202 on the carrier plate 200. The distance between the tooling locations 202 can be sized to correspond to a length of body portion 53 to be used in a bag 700. Tooling locations 202 thus can also serve a quality control function for a bag 700 and body portion 53. Tooling locations 202 can also also utilized to position the carrier plate in heat sealing machinery as discussed further herein. To form a fusion area 66, upper portion 161 of folded body 53 on carrier plate 200 can be placed within lower portion opening 102 of top 51. Alternatively, or in conjunction carrier plate guides, marks on the fabric portions and/or use of lasers can help guide the formation of desired overlap areas.
To form a fusion area 67 lower portion 162 of body 53 can be placed through open wider portion 104 of bottom 52 while on carrier plate 200 to form an overlapped fusion area 67. Alternatively, or in conjunction with body guides, marks on the fabric portions and/or use of lasers can help guide the formation of desired overlap areas.
Preferably one or more holding clamps 203 are provided on the carrier plate to help securely hold one or more of the bag fabric pieces or other parts in place on the carrier plate 200 after aligning the respective bag pieces or parts with respective tooling 202 or guides 201, 204, or 205, or markings or lasers. This important to help ensure fusion areas of the bag are properly aligned in heat sealing machine.
A document pouch 73 and label 74 can also be positioned on the body portion 53 while on carrier plate 200. Document pouch 73 and label 74 can be held in place during assembly via fabric tape for example, or with other known suitable means.
Carrier plate 200 preferably has openings at least in the fusion areas 65, 66, 67 and 68 so that when placed in a heat sealing machine, e.g., in machine 300, upper and lower mating heat seal bars can come into contact with top and bottom surfaces of the respective heat fusion areas 65, 66, 67, 68. Carrier plate 200 also preferably has openings that correspond to designated lift loop assembly 56 locations for a bag and a diaper or cover 61 location for a bag, so that when a bag including lift loop assemblies 56 and a bottom cover or diaper 61 assembled thereon is moved into a heat sealing machine 400, for example, as discussed further herein, respective upper and lower mating heating sealing bars can come into contact with a lift loop assembly upper surface and a lift assembly bottom surface, and with a diaper upper and bottom surfaces and form a heat sealed joint in the designated connection areas for the lift loop assemblies 56 and diaper 61.
In addition to use of clamps 203 to hold the fabric pieces in position on the carrier plate, tape can also be used to temporarily couple one or more, or all, of the fabric pieces and bag parts in appropriate position, e.g., for a document pouch 76 or lift loop assembly 56.
After assembling the bag fabric pieces on a carrier plate 200, the assembled bag pieces, while still clamped onto carrier plate 200 can be moved into position in an impulse heat sealing machine, e.g., in main body impulse sealer machine 300 (see
One or more stops can be provided on a machine 300, e.g., a center stop to aid in properly aligning a carrier plate 200 in the machine 300. Preferably a safety feature will be included, e.g., programmed by a control program 600, wherein a sensor can sense when the carrier plate 200 is properly aligned, and wherein a heating cycle will not be able to start until a carrier plate 200 is properly aligned in the machine 300.
As shown in
Preferably mounting table 305 has openings 341, 342, 343, 344, 346 that correspond to locations of the heat sealing systems 331, 332, 333, 334, 336 so that the respective heat sealing bars can come into contact with bottom and upper surfaces of the fusion areas 65, 66, 67, and 68 when the respective heat seal bars are lowered into position.
Preferably each of the heat sealing systems 331, 332, 334 and 336 have upper and lower mating heat sealing bars. Document pouch sealing bar 304 can have only an upper heat sealing bar. After a cycle is initiated at a control panel 601, the five upper heat seal bars 301, 302, 303, 304, and 306 are pushed downward by respective pneumatic cylinders 309 (e.g., preferably at 30 psi (207 kilopascal)). Upper bar 301 is pushed downward to contact a top surface of fusion area 65 and to mate with lower bar 322 which is in contact with a bottom surface of fusion area 65. Upper bar 302 is pushed downward to contact a top surface of fusion area 66 and to mate with lower bar 321 which is in contact with a bottom surface of fusion area 66. Upper bar 304 is pushed downward to contact a top surface of fusion area 67 and to mate with lower bar 318 which is in contact with a bottom surface of fusion area 67. Upper bar 306 is pushed downward to contact a top surface of fusion area 68 and to mate with lower bar 317 which is in contact with a bottom surface of fusion area 67. Upper bar 303 is pushed downward to contact an upper surface of document pouch 73.
The upper heat sealing bars 301, 302, 303, 304 and 306 and lower heat sealing bars 317, 318, 321 and 322 can heat seal at the five heat fusion areas for discharge spout, bottom, top, fill spout and document pouch.
In various embodiments, lower heat sealing bars can be constructed similar to upper heat sealing bars.
The pneumatic cylinders 309 preferably remain in the extended position during a temperature ramp-up period, a temperature bake time and a cool-down time. At the completion of the temperature times including the cool-down time, the pneumatic cylinders can then retract and are ready for the next cycle. A cooling time is preferably included to ensure that the bond between bonding coatings on fabric pieces in the fusion area, or between a bonding coating and standard fabric laminate coating in a heat fusion area is formed. Preferably pressure is still applied during the cool-down time to help ensure that a solid bond/fabric joint is made between the bonding coating and standard fabric coating, or bonding coating and bonding coating, on the respective fabric pieces in the fusion area that is being heat-sealed.
A ramp up time frame to get to the desired temperature can be 8 to 12 seconds. Heat sealing time can vary depending on the thickness of the materials to be fused together. For example with machine 300, a heat sealing time can be variable at each heat sealing assembly. A ramp up time to get to temperature and cool down time can also be variable for each heat sealing assembly on a single heat sealing machine or single heat sealing station. For example, sealing time can be longer at the bottom to body joint if the bottom has a thicker fabric than the top, than for a top to body joint. Cool down time can also be variable at each heat sealing assembly in a given machine. In production, assembly of the bag on an assembly table through heat sealing in the machine can typically be about 2.5 minutes, for each machine 300 and 400.
As shown in
A table or frame for a machine 300 can be similar to a table or frame previously described with regards to machinery depicted in
After the cooling time in machine 300, joint 126 in fusion area 65, joint 127 in fusion area 66, joint 128 in fusion area 67, and joint 129 in fusion area 68 will have formed for a bulk bag 700. Document pouch 73 can also be heat sealed to the body portion 53. The carrier plate 200 with the heat sealed bag 700 thereon can now be removed from machine 300 and transferred to a lift loop and diaper/bottom cover assembly table 251. Preferably a loop assembly and diaper cart 460 is located near table 251. Cart 460 preferably is designed to exacting dimensions to hold a full day's production of lift loop assemblies 56 that preferably include a lift loop panel 59 and lift loop 60. Lift loop 60 preferably is already attached to lift loop panel 59, e.g., via sewing or heat sealing. Preferably lift loop assemblies 56 are in folded configuration when placed on cart 460. Diaper/bottom covers 61 can also be placed on cart 460 in flat unfolded configuration.
In various embodiments, a lift loop panel assembly 56 can be assembled on the bulk bag body so that, when using a substantially rectangular shaped patch that is positioned on each gusseted edge of bag body portion, the longer length sides of a panel 56 are positioned substantially vertically on a the bulk bag body. Loop guides can also be included on a carrier plate to aid in positioning the loop assemblies on a bag. When arranged in this manner, it is preferred to also include tape, e.g., polypropylene or polyethylene fabric tape, along an inner vertical edge of the lift panel 59. Tape can also be included along each edge. The tape can be attached on the bag body via an adhesive backing on the tape. During experimentation, stress lines can develop from the top point of sewing of the loop to about 45 degrees downward of the lift loop, and the bag fabric can break around the center of the patch line. In such instances it goes into peel and weft horizontal influence is higher. By adding the tape along an inner edge of the patch, this prevents it from going into peel. Testing has shown that, a bag including tape along an inner edge of the lift loop patch can hold 9000 to 12000 pounds (4,082.3 to 5,443.1 kilograms). The tape along the lift loop panel 59 also helps prevent curling of the bag fabric around the lift loop panel 59 which can occur during heat sealing. The tape helps prevent center yarn stretching which can occur during heating.
In other embodiments, a lift loop assembly 56 can be placed on the bag body 53 so that the longer sides of the panel are substantially horizontal on the bag body 53 with the lift loops sewn to at or near the center of the panel 59 when in this horizontal orientation. In this embodiment, tape can be eliminated. The orientation of the patch in this embodiment prevents going into a peel position and prevents the bag tearing as discussed above when positioned in a substantially vertical orientation. With sewing lift loops on bags, it is noted that threads on lift loops typically fail or break below the lift loop. In a heat sealed bag as described in one or more embodiments herein, stress on the loop comes from above the loop and not below the loop causing it to go into peel pressure. Tape can potentially still be utilized though, along with horizontal orientation of the patch, to help prevent the fabric from curling or wrinkling along the panel edges if desired.
Cart 460 is preferably designed to be unloaded from any side. Cart 460 can include a platform 461, e.g., a U-Boat truck platform, a parts platform 462 and a plurality of parts cage rods 406. The parts cage rods 406 can be positioned on the parts platform 462 so as to hold a plurality of lift loop assemblies 56 and diapers or bottom covers 61 in spaces between the cage rods 406, as shown in
Preferably the heat sealed assembled bag 700, while still clamped onto carrier plate 200, can be moved from machine 300 onto the loop/diaper assembly table 251. The lift loop assemblies 56 and diaper 61 can then be placed in their proper position on the bag 700 while still on carrier plate 200. As discussed with other embodiments, the diaper and lift loop patch can be highly oriented polypropylene fabric, or other fabrics can also be used. A lift loop assembly 56, wherein the lift loop panel 59 is folded at a fold line 85 can be placed so that fold line 85 is in contact with edge 414, 415, 416, and 417 of body 53, with one portion of the folded patch 59 extending along a gusseted fold of the bag 53, and with the other portion of the folded patch 59 extending either along a top or bottom surface of bag 53. When assembling the patch 59 on a body 53, the patches can be located on body 53 as shown in an open configuration in
Bottom cover 61 also can be positioned on the bag 700 while on carrier plate 200. Preferably cover 61 is positioned so that it extends from opposing sides of bag 700 across a bottom 107 of the bag, e.g., extending from a first side 163, across a width of bottom 52, over discharge tube 58, and to a second side 164. Marks on the fabric portions can add in placement of the cover 61. As previously discussed herein, preferably cover 61 is positioned so that when the bag is in an open configuration the distance between a fold 105 (at the location where cover 61 extends from bottom 52 over joint 128 to one side 163 of bag 700) and a fold 106 (where cover 61 extends from bottom 52 over joint 128 to a second side 164) is shorter than a width of bottom 52 so that when cover 61 extends across a width of bottom 52 to opposing sides of body 53, it cinches a bottom area 107 of bag 700, and causes an uplift of the bag bottom which provides even more support to bag 52. It also provides a flatter surface for a bottom of the bag.
After positioning the lift loop assemblies 56 and cover 61 on the bag 700, the carrier plate 200 can be moved into position in a heat sealing machine, e.g., a loop diaper impulse sealer machine 400, as shown in
A machine 400 for sealing lift loop assemblies and a diaper 61 can have a frame or mounting table 407 and three heat sealing assemblies. Heat sealing assembly 421 has an upper first loop heat sealing bar 402 and a lower mating first loop heat sealing bar 412. Heat sealing assembly 422 has a second upper loop sealing bar 420 and a second lower mating loop heat sealing bar 413. Heat sealing assembly 423 has an upper diaper heat sealing bar 406 and a lower mating diaper heat sealing bar 411. Preferably frame 407 has an opening 431 positioned so that upper diaper seal bar 406 and lower diaper seal bar 411 can be moved into contact with one another. Preferably frame 407 has an opening 432 positioned so that upper first loop seal bar 401 and lower first loop seal bar 412 can be moved into contact with one another. Preferably frame 407 also has an opening 433 positioned so that upper second loop seal bar 420 and lower second loop seal bar 413 can be moved into contact with one another.
Preferably carrier plate 200 is positioned in machine 400 so that heat sealing assembly 421 can heat seal two lift loop assemblies to bag 700 at one time, e.g., when lift loop assemblies are positioned at edges 416 and 417 of a gusseted body 53. Preferably lift assemblies around edges 416 and 417 are positioned on the carrier plate and over opening 432. Preferably carrier plate 200 also has an opening under designated lift loop assembly 56 locations. When positioned in machine 400 in this manner pneumatic cylinders 403 can lower the first upper loop heat seal bar 401 to contact an upper surface of a top lift loop assembly 56 while lower first loop heat seal bar 412 is in contact with a bottom surface of another lift loop assembly 56.
Similarly, preferably carrier plate 200 is positioned in machine 400 so that heat sealing assembly 422 can heat seal two lift loop assemblies to bag 700 at one time, e.g., when lift loop assemblies are positioned at edges 414 and 415 of a gusseted bag body 53. Preferably lift assemblies 56 around edges 416 and 417 are positioned on the carrier plate and over opening 433. Preferably carrier plate 200 also has an opening under the said designated lift loop assembly locations. When positioned in machine 400 in this manner pneumatic cylinders 403 can lower the second upper loop heat seal bar 420 to contact an upper surface of a top lift loop assembly 56 while lower second loop heat seal bar 413 is in contact with a bottom surface of another lift loop assembly 56.
Regarding heat seal assembly 423, preferably diaper 61 is positioned on bag 700 on carrier plate 200 so that it is over an opening in the carrier plate 200 that can accommodate the shape and dimensions of the diaper fusion area and the seal bar. Preferably when carrier 200 is positioned in machine 400 the diaper 61 on carrier plate 200 is also positioned over opening 431. When positioned in machine 400 in this manner pneumatic cylinders 403 can lower the upper diaper heat seal bar 406 to contact an upper surface of diaper 61 assembled on bag 700 while lower first loop heat seal bar 411 is in contact with a bottom surface of diaper 61 assembled on bag 700.
Preferably the three upper side heat sealing bars 402, 420 and 406 are pushed downward (e.g., at 30 psi (207 kilopascal)) by pneumatic cylinders 403 to the mating three lower side heat sealing bars 412, 413, 411 with bag 700 having the lift loop assemblies and diaper positioned thereon between the said respective upper and lower heat sealing bars.
As shown in
Lower heat sealing bars can be of similar construction to upper heat sealing bars.
One or more stops can be provided on a machine 400, e.g., a center stop to aid in properly aligning a carrier plate 200 in the machine 400. Preferably a safety feature will be included, e.g., programmed by a control program 600, wherein a sensor can sense when the carrier plate 200 is properly aligned, and wherein a heating cycle will not be able to start until a carrier plate 200 is properly aligned in a machine 400.
Once positioned in the machine 400, a machine cycle can be started at a second control panel 600 wherein the pneumatic cylinders 403 are lowered into position. The pneumatic cylinders 403 preferably remain in an extended position during a temperature ramp-up period, a temperature bake time and a cool-down time. At the completion of the temperature times, the pneumatic cylinders can then retract and are ready for the next cycle. A cooling time is preferably included to ensure that the bond between bonding coatings on fabric pieces in the lift loop assembly and diaper connection areas, or between a bonding coating and standard fabric laminate coating in the lift loop assembly and diaper connection areas is formed.
After the cooling time, the lift loop assemblies 56 and diaper 61 will be heat sealed to the bag 700 with a heat sealed joint formed between a bonding coating and standard laminate coating on the respective fabric pieces in the respective connection areas, or between a bonding coating and a bonding coating on the respective fabric pieces in the respective connection areas.
The assembled bag 700, while still clamped onto the carrier plate 200 can then be moved out of machine 400 and onto a finished bag unload table 232. At this time, the bag 700 can be unclamped from the carrier plate 200 and can be folded for storage or transport and moved to a finished bag area. The carrier plate 200 can then be moved, e.g., in the direction of arrow 256 onto a conveyor system or conveyor table 253 where it can automatically be returned to a starting position to begin a new bag assembly cycle, wherein carrier plate 200 can be removed from conveyor 253 and move, e.g., in the direction of arrow 257 onto main assembly table 250. The carrier plate 200 can also be manually returned or slid on table 253 back to a starting position.
Referring to
A carrier plate end rail and side rail sub-assembly 1301 is also depicted (see
Preferably, side and end rail pop rivet and screw mounting holes are drilled through both the base plate and the rails after the rails are secured in, e.g., with clamps.
Additional parts and materials labeled in
The figures depicting carrier plates 200 and 1300 depict a preferred embodiment of the guides and locations on a carrier plate that can be used with the invention. Other parts and materials known in the art potentially can be included to form suitable guides to help with bag portion positioning, and guides potentially could include other configurations, on a carrier plate to be used in one or more embodiments of the invention.
As part of the automation process, carrier plates comprising different dimensions can be fabricated based on desired bulk bag dimensions. Different machines 300 and 400, for example, can also be fabricated to correspond to dimensions of respective carrier plates. In one or more embodiments, the same machines 300 or 400 can be used to form bulk bags of differing dimensions, e.g., if the bags have differing heights so only the length of a body for example is changed. One or more heat sealing bar assemblies, for example, may be moveable within a machine to allow for use of a one machine to heat seal bag joints for bags having different dimensions.
In various embodiments a carrier plate can have one or more extendable and retractable portions to change the dimensions of the carrier plate, e.g., in length or width, or both length and width.
In various embodiments bag dimensions and tolerances can be modified by changing the length of the bag body portion. In various embodiments, carrier plates of more than one dimension corresponding to different bag body portion lengths can be fabricated. In various embodiments, carrier plates of more than one dimension corresponding to different bag fabric portion dimensions can be fabricated.
In various embodiments, one or more carrier plates can be extended or reduced in length to accommodate different bag fabric portions with differing dimensions, e.g., bag body portions of differing lengths. In various embodiments, one or more carrier plates can be extended or reduced in width to accommodate different bag fabric portions with differing dimensions.
In various embodiments a machine 300 or 400, or other machines as shown and described herein, can be extended or reduced in length to accommodate carrier plates of different lengths or other dimensions, wherein one or more of the heat sealing bars are movable to a location to correspond to carrier plates of different sizes and to fusion or bonding areas of bag fabric pieces on the carrier plate. In various embodiments a machine 300 or 400 can be extended or reduced in width to accommodate carrier plates of different widths, wherein one or more of the heat sealing bars are movable to a location to correspond to carrier plates of different sizes and to fusion or bonding areas of bag fabric pieces on the carrier plate. In various embodiments a machine 300 or 400 can be extended or reduced in length and/or width to accommodate carrier plates of different lengths and/or widths, wherein one or more of the heat sealing bars are movable to a location to correspond to carrier plates of different sizes and fusion or bonding areas of bag fabric pieces on the carrier plate.
In various embodiments, tables 250, 251, 252 and frame/table 305 and 407 of machines 300 and 400 can have longitudinal guides to facilitate sliding of the carrier plate 200 from one table or machine to another.
Turning now to
Preferably upper seal bar 501 includes a heating element cover 521, which can be a Teflon cover, and which can be held in place by clamp bars 519. Preferably heating element 512 is a single piece construction and is held in place by a pivoting clamping assembly comprising parts sealing element pivot mount 513, insulation tape 514, interior mounting flange 515, exterior mounting flange 516, and clamping plate 517. The heating element 512 can be stretched to proper tension by two springs 518.
Preferably heating element 512 is insulated from the seal bar by a rubber insulation material 520, which can be rubber.
A heat sealing bar system 500 can include the following parts as shown in
Heat seal assemblies 331 and 336 can include upper seal bar assemblies similar to those shown in
In the prior art, Teflon covers can be included with heat seal bars but they are attached with an adhesive, e.g., tape, to a heating element. During the heating process the Teflon typically start peeling off. In a preferred embodiment of heat sealing assemblies in one or more embodiments of machinery as described herein, a Teflon cover is clamped on or over a heating element which can eliminate the problem of peeling off of Teflon in the prior art. This also eliminates the problem of adhesive sticking to the heating element that often is scrapped off in the prior art.
An upper heat seal bar assembly preferably has a three axis pivot yoke that can include the seal bar assembly 551, a washer 552, acorn nut 553, nylon washer 554, clamping collar 555, yoke mount 556, pivot mounting plate 558, pivot yoke 559, and pivot rod 560. A three axis pivot yoke assembly can help insure uniform pressure during the heat sealing process when the upper heat sealing bar is pressed against its mating lower seal bar by the two pneumatic air cylinders.
A seal bar heating element cover 570, which can be Teflon, can be held in place by clamp bars 567. Preferably the heating element 569 is single piece construction. Heating element 569 can be held in place by a pivoting clamping assembly that can include clamping plate 561, exterior mounting flange 562, interior mounting flange 563, insulation tape 564, springs 565 and sealing element pivot mount 566. The heating element 569 can be stretched to its proper tension by two springs 565.
Preferably a heating element 569 is insulated from the seal bar by a rubber insulation material 571.
A heat sealing system as shown in
A heat sealing system as shown in
In various embodiments of heat sealing assemblies that can be used in heat sealing machines, one or more heating elements which can be constructed in a similar manner as shown in the figures can be provided of varying dimensions, wherein the dimensions of a heat sealing bar assembly alone or in combination with one or more additional heat sealing bar assemblies can be selected based on the desired size of a heat sealed joint to be obtained on the bag to couple one or more bag portions or parts together. The heat sealing bar assemblies can be sized so that they will heat seal a desired fusion or connection area and to provide a desired size heat seal joint that couples together fabric pieces or other parts of a bulk bag.
In one or more embodiments, an overlapped fusion area can determine the dimensions of a heat sealed joint, even if the heat seal bars extend a distance beyond the heat sealed joints, e.g., when a standard coating to bonding coat joint or seam is formed in the seal area. If a seal bar extends beyond the area where a bonding coating and standard fabric laminate coating are in contact, a bag joint will form where the standard coating and bonding coating are in contact, but not where a standard and standard coating are in contact. As discussed, this can be desirable to help ensure nongraspable edges along a bag joint.
In various embodiments heat sealing machinery and tables through or on which carrier plates can be transferred include step guides at the beginning and end of the table or machine that facilitate one-way travel in the assembly line sequence, wherein entrances can point down and exits can point up. Preferably, each next step guide is slightly higher than a previous step guide. At table transition points, the angle at the top of a step guide can be about ⅛ inch (0.32 cm) higher, for example, than the table surface.
In preferred embodiments, heat sealing machinery includes one or more lasers or lights that can provide an outline of desired fusion areas and help ensure fabric pieces are overlapped properly and that positioning tape, if utilized, is in the correct position.
For lift loop and diaper heat sealing machines, 10 transformers can be included based on the different structure of the heating elements and configuration of the heat sealers.
Transformers 603 can step down voltage from 240 VAC to 12-48 VAC, which powers the heating elements.
The PLC 601 preferably uses software that uses a PID (proportional/integral/derivative) closed loop algorithm to control temperature ramp and stability during the heating process. The PID algorithm must be tuned for each element size. The tuning involves the setting of the proportional, integral and derivative values used by the PID algorithm.
In some embodiments, a single PLC 601 can control multiple different control panel units 600 and/or multiple different machines, e.g., 2, 3, 4, 5, or more different control panels and/or 2, 3, 4, 5 or more machines.
In various embodiments, a PLC can provide information on control panels and units that are at another location for heat sealing.
In various embodiments, a PLC can control 5 different units and 9 different elements, e.g. 9 different transformers and 9 different relays.
Temperature ramp up during the heat sealing process is performed with seal bars closed and fabric under pressure to ensure stability with ramp up.
Preferably each heating element has two (2) thermocouple sensors monitoring the temperature of the element. One sensor can be used for control and the other can be used as a fail-safe check.
Soft padding material, e.g., silicon rubber, is preferably installed under each sensor to ensure good pressure applied to both the control and check sensors. Sensor readings tend to vary with varied pressure and padding can help to equalize the pressure across the sensors.
Once the heat seal desired temperature is reached there is preferably a delay, e.g., a five (5) second delay, to allow the temperature to stabilize, and then the PLC 601 calculates temperature averages for the control and check sensors for the remainder of the heat seal time. Samples are preferably taken twice per second. At the end of the heat seal time the averages for the control and check sensors are preferably compared by the PLC 601, and a dual sensor fault is triggered if the values are out of a specified tolerance. In the event of a dual sensor alarm, the heat sealing cycle can be allowed to complete but engineering is preferably notified to check the machine and clear the alarm.
Preferably a timeout fault is triggered and a heat sealing cycle is terminated if a set-point temperature is not reached within a desired time frame, e.g. within 10 to 20 seconds. In such a situation, engineering is preferably notified to check the machine and clear the alarm.
An overshoot warning can be triggered if the overshoot exceeds the overshoot warning threshold which varies per heating element. The cycle can be allowed to complete. The operator can clear the alarm, but preferably is advised to check the bag for damage. An overshoot can be, for example, if the temperature goes about 5 to 10 degrees above desired temperature during ramp up time. If the overshoot lasts for a split second, for example, it should not be harmful to the bag, but if the overshoot lasts too long, it can cause burning or weakening of bag fabric.
An overshoot fault is preferably triggered by three (3) consecutive overshoot warnings. The cycle can be allowed to complete, however engineering is preferably notified to check the machine and clear the alarm.
A high temperature fault can be triggered if either the control or check sensor exceeds the high temperature trigger at any point in the cycle. The cycle can be terminated and engineering is preferably notified.
A low temp fault can be triggered if the control sensor temperature drops below a set threshold during the heat sealing time. The cycle preferably is terminated and engineering notified.
An end-stop equipped with a positioning sensor can ensure correct positioning of the carrier plate within the machine. Preferably the end-stop sensor must be triggered by the carrier plate prior to the operator initiating the heat seal cycle. This ensures that the carrier plate is in correct position and that heat sealing bars are aligned with desired heat seal locations for desired heat sealed joints.
Preferably all machines can be networked together. All machines can be monitored using Siemens SCADA software, for example. Faults as well as other critical data values are preferably logged into a central database. Real-time production values can be viewed and monitored by management or users and reports can be automatically generated. Fault notifications are preferably automatically sent to maintenance personnel in the event of machine faults.
Preferably every element has 2 sensors, and can have 1 control for a PLC and 2 fail safes to make sure the PLC does not malfunction.
In various embodiments, the monitoring during the process and data recorded lets an operator know whether a heat sealed joint or bond is of good quality or as desired. An operator in most cases cannot tell by just looking at a heat sealed joint if it was sealed properly. If temperature was too high, an operator may be able to tell by looking at the fabric which may have evidence of burning, but if the temperature was too low, an operator will not be able to tell if the joint is of desired quality.
In various embodiments, different temperature set points for each heating bar are possible, e.g., about 265 degrees (129 degrees Celsius) may be a targeted temperature for sealing, and about 165 degrees (74 degrees Celsius) may be a targeted temperature for end of cool down time and lifting of the seal bars.
One or more alarms can be red flashing, or other color flashing light.
In some embodiments, 20 seconds is the targeted time for a heat seal bar to reach the targeted temperature. If not reached in that time an alarm can sound or the machine can shut down, e.g., be set to automatically shut down.
Preferably all data during heat sealing, including time frames, temperatures, pressure, etc. and faults or alarms are recorded.
Each control panel preferably is networked to a main computer, e.g., with Siemens software.
A screen 599 on a control can display multiple views and different data being collected or monitored on one or more machines, including on off location machines.
A default screen can be included with a control panel 600 which can monitor what is happening with every machine and electrical component of the system.
In various embodiments of the intermediate stage fusion closed loop production line system and method, a bulk bag with heat fused seams can be manufactured in about 2.5 minutes.
In various embodiments of the intermediate stage fusion closed loop production line system and method, the assembly process and heating sealing process for each machine 300 or 400, can take about 2.5 minutes, for a total of about 5 minutes to manufacture a complete bag 700. During an assembly line production, both machines 300 and 400 can be in operation at one time so that two different bags can be being prepared sequentially with some of the same overlap time. Output of a completed bag therefore can be at about every 2.5 minutes during assembly line production. In various embodiments of the intermediate stage fusion closed loop production line system and method, a bulk bag 700 with heat fused joints can be manufactured in under 2 minutes, or between 2 to 10 minutes.
In various embodiments of the intermediate stage fusion closed loop production line system and method, a bulk bag with heat fused joints can be manufactured in under 2 minutes.
In various embodiments of the intermediate stage fusion closed loop production line system and method, a bulk bag with heat fused joints can be manufactured in under 2 minutes, 2 to 7 minutes, or over 7 minutes.
Although not shown in the figures, a conveyor system can also be included that sends a carrier plate 200 from the finish/unload table 252 to the conveyor table 253, and also a conveyor that can send the carrier plate 200 from the conveyor table 253 to the main assembly table 250. In various embodiments, a carrier plate from machine 300 can also automatically be conveyed to the lift loop assembly table prior to entering machine 400.
In various embodiments operators for assembling one or more bags on a carrier plate and operating heat sealing machinery throughout the automated process can be trained in about two hours. In other embodiments they can be trained in under 2 hours. In other embodiments they can be trained in about 2 to 7 hours. In other embodiments that can be trained in one day. In the prior art of sewing bulk bags, training periods typically are about 90 days to learn how to sew the bags.
In various embodiments, one-way stops can be included on the carrier plate, wherein the stop includes a ramp and wherein it insures that the corner from the top to bottom and spout to top is always perpendicularly aligned. If a fabric piece goes over the stop, it is an indication the fabric piece is oversized. It can also provide information as to whether a fabric piece is undersized.
Preferably one or more embodiments of heat sealing machinery as shown and described herein can include center stops and end stops for positioning of the carrier plate.
In preferred embodiments of heat sealing machinery, heat sealing bars can be coupled to the machinery with quick connect and disconnect features to facilitate changing out the sealing bars as needed.
A quick disconnect feature can include removing bolts, and pulling out rods, after disconnecting electrical components at top. To re-connect, the rods, bolts and electrical can be re-assembled together.
In various embodiments, a carrier plate can function as a quality check tool for bag parts assembly, machine set-up tooling, and an inspection tool for assembly of the bags and machinery. By combining these three functions in one component, it helps keep close tolerances in the bag formation, accuracy and quality control. If different tools are used as a quality check for assembly, machine set-up tooling, and inspection, such tolerances can be lost.
In various embodiments, a carrier plate can function as a quality check tool for bag parts assembly, machine set-up tooling, and/or an inspection tool for assembly of the bags and machinery.
In the heat sealing machinery, multiple axes, e.g., 2 or 3 axes, can be utilized to help ensure equal pressure during heating sealing and to helps sensor sense the pressure. In the prior art, if multiple axes are utilized it was for the purpose of alignment or to move the parts at different angles.
Referring now to
As shown in the Figures, different configurations of heat sealing stations, and/or different configurations of heat sealing machinery included at one or more heat sealing station can be provided. In one or more embodiments, one or more heat sealing assemblies can be included at one or more heat sealing station. The one or more heat sealing assemblies provided at a heat sealing station can be the same as an embodiment shown in the drawings or different from what is shown in the drawings. For example, in one or more embodiments, a document pouch heat sealing assembly can be included at a different heat sealing station and not at a first heat sealing station as shown in
An overall heat sealing assembly line can also be modified if desired, from what is shown in
In one are more embodiments, heat sealing machinery and bag or bag portion or parts configurations as described and shown herein can be used to heat seal polypropylene fabric bags. In other embodiments, the same or similar machinery and bag or parts configurations can also be used to heat seal bag of other fabric material, e.g., polyethylene bags. Parameters of the various machines could be adjusted, e.g., heat sealing temperatures based on the type of fabric being sealed. Coatings on the various bag parts can also be selected based on the type of fabric being heat sealed, e.g. a polyethylene standard fabric coating on some polyethylene bag parts could be used instead of a polypropylene standard fabric coating.
In preferred embodiments of one or more heat sealing assemblies as shown and described herein, at least one heat sealing bar assembly (e.g., an upper heat sealing bar assembly) of a pair of mating heat sealing bar assemblies is operable to have a rocking motion during the heat sealing process to help ensure that even pressure is applied on an entire heat sealing joint area during the heat sealing process.
In preferred embodiments of heat sealing assemblies for forming a joint at a fill spout to top, top to body, body to bottom, bottom to discharge tube, and/or diaper/bottom cover joint locations, an upper heat seal bar assembly can have to two pin axes, e.g., at the locations where a heat seal bar assembly is coupled to the pneumatic cylinders.
Referring to
A second pin central longitudinal axis 444 is also shown. A shaft or pin 445 is positioned through lower opposing openings of clevis 509 which can also be coupled to a second pneumatic cylinder at arrow 449, and wherein the shaft or pin 445 is also positioned through opposing openings 448 of a pair of opposing brackets 507, with the brackets 507 also coupled to the heat sealing bar assembly 510. The openings 448 of opposing brackets 507 are preferably slotted, e.g., oval with a diameter across the width of the openings that is larger than the diameter across a width of the shaft or pin 445, which can define a slotted opening 448. Preferably the slotted openings 448 allow some left to right movement of pin or shaft 445 in the slotted opening, but minimal or no up and down movement in the slotted openings 448. With this configuration, when pin or shaft 445 is in openings 448 the pin 445 can move in a left or right direction in the opposing slotted openings 448, the movement enables angular rotation of the pin or shaft 445 in non-slotted openings 447 of brackets 446 along pin axis 443, while the heat seal bar assembly 510 is maintained in a relatively fixed horizontal location over the heat sealing area. The angular rotation along pin axis 443 can be between about 0 to 3 degrees, for example, which enables a side to side or left to right rocking of the seal bar assembly 510 along a central seal bar axis.
With this configuration the brackets 446 are operable to hold the heat sealing bar assembly 510 in a relatively fixed location, e.g., a substantially horizontal location, over the heat sealing joint area of the bag, while the brackets 507 enable the angular rotation along pin axis 443 that can effect rocking of seal bar 510 in a left to right, or side to side direction designated by arrows 559, as the heat seal bar is heat sealing a bag joint.
The center distances between clevises 509 is fixed, and the slotted openings 448 of brackets 507 allows no stress to be placed on the center distance between clevises 509 when the cylinders are pushing down seal bar 510 onto fabric to be sealed. As the seal bar comes down on uneven fabric surfaces the angular rotation along axis 443 allows the angle to increase so the cylinders don't bind up, and allows even pressure to be applied to the fabric surfaces.
As indicated, a pair of opposing slotted positioning brackets as shown in one or more embodiments of the heat sealing bar assemblies, e.g., slotted brackets 359, 448, 545, 613, 681, 752, 1122, and/or 1583 enable a rocking motion of the heat seal bar assembly. When a shaft or pin is positioned through the slotted openings and through the cylinder yoke, the slotted openings allow rotational movement of the pin or shaft that is positioned through non-slotted brackets, e.g., brackets with non-slotted openings 358, 446, 546, 614, 682, 753, 1121, 1584, which allows the heat sealing bar assembly to self-adjust, or self-align, on the fabric during heat sealing, even when different levels of thickness or densities are present in the multiple layers of fabric in a given heat sealing area. With the rocking motion, even where the fabric is uneven, an equal pressure, or at least substantially equal pressure can be applied to all the fabric in the joint area. The rocking motion allows the upper and lower heat sealing assemblies to mate in a perfectly parallel, or at least almost perfectly parallel fashion, while heat sealing a joint.
If equal pressure is not applied during heat sealing, e.g., at locations including higher areas of fabrics, then hot spots, or bright spots, or shiny spots can develop during heat sealing, where those higher areas start to melt, or where the heat starts to damage to the fabric.
If a pair of slotted opposing openings where not present in the brackets, e.g., in brackets 507 or 1121, when the heat seal bar came down at different levels of thickness on the fabric, the cylinders would bind up. This can occur because when the heat seal bar came down at different levels of thickness on the fabric, the cylinders will bind up when trying to push the heat seal bar down in parallel position. If no rocking is allowed, e.g., if pin or shaft 445 cannot rotate on pin axis 443, the seal bar will try to go in at an angle and try to push the cylinders' center distance apart which binds them up and causes the heat seal bar to hit the surface unevenly, with no ability to rock or self-adjust or self-align. When a pair of positioning brackets with opposing slotted openings is included, when the cylinders are pushing down the heat seal bar, as an angle increases when the heat seal bar comes down on a mismatched area, the slotted opening allows for the angular rotation of a pin or shaft 445 for example along pin axis 443 and rocking and self-adjusting of the heat bar so binding up of the cylinders does not occur.
A pair of positioning brackets 446 for example with non-slotted openings 447 therefore can keep the seal bar in a relatively fixed horizontal location, while the brackets 507, for example, enable rocking of the seal bar, e.g., in a left to right direction during the sealing process at the fixed location.
Preferably the angle of rotation along a pin central longitudinal axis, e.g., pin axis 443 is in a range that will accommodate the total differences in the material thicknesses in the heat sealing area. The angle of rotation along pin axis 443 can be 0 to 3 degrees. A 3-degree angle generally can accommodate differences in the material thicknesses in a heat sealing area. In many applications of heat sealing, the rocking may be at an angle of less than 1 degree.
If the seal bar rocks too far in any one direction, this can also cause binding up of the cylinders and damage of the fabric. This potentially can occur if two pairs of brackets with slotted openings are provided.
In the embodiments as shown in the drawings, the upper heat sealing bar assemblies can have a rocking motion, while the mating lower heat sealing bar assemblies do not have a rocking motion and remain stationary.
Referring to
As shown in
When pin 560 moves in slotted openings 495, this enables rotation of pin 560 in non-slotted openings 496 along pin central longitudinal axis 469, and rocking of the seal bar assembly 551 in a side to side or left to right direction designated by arrows 683.
It is also possible that two pairs of brackets could be included for connecting to the air cylinders, one pair with slotted openings and one pair without slotted openings. A pair of single brackets that each include a slotted and non-slotted opening is easily incorporated with the loop bar assembly given a shorter distance between the clevises in the loop bar assembly when compared to the seal bar assembly of
In various embodiments, one cylinder is preferably coupled to the seal bar with a pin through opposing slotted openings in opposing brackets, and another cylinder is preferably coupled to the seal bar with a pin through opposing non-slotted openings in a pair of opposing brackets.
A third central longitudinal axis 455 can also be provided wherein shaft or pin 493 is positioned through opposing lower brackets 556, and opposing lower brackets 494 (see
Referring to
As shown, a space or clearance designated between 459 is shown, which can be about a 0.140 inch (0.36 cm) clearance between brackets 494 and seal bar assembly 551. The space or clearance can also be about 0.12 to 0.18 inches (0.304 to 0.46 centimeters). The space or clearance between brackets 494 and seal bar assembly 551 allows rotation of pin 493 in opposing openings 470 of brackets 556 along axis 455 at a desired angular rotation. Openings 470 are preferably sized to receive pin or shaft 493 and allow rotation of shaft 490 along axis 455, but to allow little or no movement of pin or shaft in left to right or up and down directions. When pin 493 rotates counter clockwise on axis 455, the clearance goes from neutral position of about 0.140 inches (0.36 cm) to about 0. When pin 493 rotates clockwise starting from neutral position of about 0.140 (0.36 cm), the clearance goes from about 0.140 to 0.280 inches (0.36 to 0.71 cm). This enables an angular rotation along axis 455, e.g. about 0 to 3 degrees angular rotation. A same or similar clearance or space can also be included between brackets 892 and the loop seal bar assembly as shown in
The 2 axis rotation in the loop seal bar embodiment enables rocking of the seal bar in 4 directions, e.g., at an angle of about 0 to 3 degrees in the direction of arrows 680 and 683 in
Generally, when a level surface comes down on uneven fabric surfaces, there may be four uneven points. The level surface will hit the highest point and not make contact with the other three points. The 2 axis rotation enables the level surface to make contact with a minimum of three uneven surfaces and given the compressibility of the fabric as pressure is applied it can make contact with all four points of uneven surfaces.
In one or more embodiments a document pouch heat seal bar assembly as shown in
In one or more embodiments, pin movement in slotted openings of a pair of brackets attached to a cylinder is operable to cause pin rotation in non-slotted openings of a pair of brackets attached to another cylinder, which is operable to cause rocking of a seal bar along a central axis of the seal bar.
In one or more embodiments, clearance or a space provided between a seal bar and lower brackets coupled to the seal bar can effect rotation of a pin along a central longitudinal axis when the pin is positioned through the brackets that are coupled to the lower seal bar, within a desired angular range of rotation, e.g., within about 0 to 3 degrees angular rotation of the pin. The angular rotation of the pin is operable to cause rocking of the seal bar along a central axis of the seal bar.
In one or more heat sealing bar assemblies of the present invention as shown and described herein, preferably a heating element, e.g., heating elements 733, 768, 865, 864, 1151, 1520 as shown in the figures, is manufactured as a single piece including end couplers on the single piece construction. Referring to heating element 1151, for example, single piece element 1151 can include an element portion 1170 and end couplers 1168 and 1169 as an integral part of the heat element 1151, e.g., as shown in exploded view in
As shown in
The pins 1149 and 1148 hold individual parts of the assembly together and in position. Without the pins, precision would be lost. Pin 1149 can function as a locating pin, centering the parts together and keeping the ends of the assembly in vertical and horizontal position. Pin 1148 can function to prevent left to right rotation of the end assembly.
End cap assemblies including a heat strip tension block assembly 1143, for example, can be included on both ends of a main body portion 1141. Springs 1167 are provided to hold the heating element in place and to keep it in tension. The springs 1167 provide tension on pivot for 1143. Keeping the element in tension can be important to prevent the heating element from folding back on itself when cooling down for example. Preferably a pair of springs 1167 are included with both end cap assemblies.
As mentioned, and as shown in
In
Preferably an insulator, which can be coated tape, e.g., PTFE Teflon coated tape 1152, is provided on element 1170 end locations as shown in
A heat bar cover 1160 also preferably is provided in one or more heat seal bar assemblies as shown and described herein. Heat bar cover 1160 can be positioned over the coated tape 1152 on element 1170, and can be coupled to main body 1141. A cover 1160 is preferably provided to prevent the heat bar from sticking to the bag fabric which can occur even if the bag fabric is not melted. A cover 1160 preferably is coated with a non-stick material, e.g., Teflon. Although not shown in
Reference is now made to
In
When applying the coating a tubular fabric portion 57, 58 or 53, the tubular fabric portion can be positioned on a substantially flat surface. The tubular bag fabric portion 57, 58 and/or 53 can have two open end portions 1207 and 1208, and two edge portions 1202 that are not open. Coating can be applied on a first side wherein it extends past each coated edge 1202 in an over edge coating area 1201, which can be 0 to 0.4 centimeters, example. The coating can also be applied on a second side of the tubular fabric portion 57, 58, 53 in the same manner so that it extends beyond each edge 1202 in an over coated area 1201. When coating is applied to the second side, the over edge portion of the second side will adhere to the over edge portion of the first side coating.
In a final coated tubular fabric portion, two overedge coating areas 1201 will be present. Each tubular piece can be gusseted so that a first over edge portion 1201 is on a top side of a gusset edge, and the second over edge portion 1201 is on a bottom side gusset edge, as shown in
When a bag body portion, for example, is gusseted as is shown in
Applying a coating with an overedge coating portion as described herein can be used for both a bonding coating or a standard fabric laminate coating, e.g., a standard polypropylene fabric coating.
When a applying a coating to bag fabric portions, the coating is applied in a liquid sheet that can be about 2 to 5 mils (0.05 to 0.13 millimeter) thick. For a body portion for example, an about 48 inch (376 cm) tube is flattened to about 74 inches (188 cm) and the outer edges get stronger at the center.
Referring now to
The dashed line in
Surfaces that are not heat sealed together to form a bag joint can be fabric surfaces, or standard laminate fabric coating surfaces. If in a fold location a bonding and standard coating, or a bonding and bonding coating will be in contact in an area where a bond is not wished to be formed, a buffer material, e.g., wax paper can be included.
If it is desirable in some bag configurations to form a bond in a fold area between one or more layers under heat and pressure, a bond can be formed by having a bonding to bonding coating in contact, or a standard to bonding coating in contact when under heat and pressure, for layers to be heat sealed together.
The heat sealing configuration as shown in
All measurements disclosed herein are at standard temperature and pressure, at sea level on Earth, unless indicated otherwise. All materials used or intended to be used in a human being are biocompatible, unless indicated otherwise.
The foregoing embodiments are presented by way of example only; the scope of the present invention is to be limited only by the claims.
This application claims the benefit of and/or priority to U.S. Provisional Patent Application Ser. No. 62/492,900, filed on 1 May 2017 and U.S. Provisional Patent Application Ser. No. 62/419,317, filed on 8 Nov. 2016, each of which are hereby incorporated herein by reference thereto. This application is related to U.S. patent application Ser. No. 14/297,331, filed on 5 Jun. 2014 (published as no. US2014-0360669A1 on 11 Dec. 2014), and U.S. patent application Ser. No. 14/297,441, filed on 5 Jun. 2014 (published as no. US 2014-0363106A1 on 11 Dec. 2014), each of which claims the benefit to/of and priority to/of U.S. Provisional Patent Application Ser. No. 61/831,476, filed on 5 Jun. 2013; U.S. Provisional Patent Application Ser. No. 61/890,664, filed on 14 Oct. 2013; U.S. Provisional Patent Application Ser. No. 61/909,737, filed on 27 Nov. 2013; U.S. Provisional Patent Application No. 61/994,642, filed 16 May 2014, each of which is hereby incorporated herein by reference. International Application Serial No. PCT/US14/41154, filed on 5 Jun. 2014 (published as no. WO2014/197727 on 11 Dec. 2014), and International Application Serial No. PCT/US14/41155, filed on 5 Jun. 2014 (published as no. WO2014/197728 on 11 Dec. 2014), are each hereby incorporated herein by reference. This application is additionally related to U.S. Provisional Patent Application Ser. No. 62/252,270, filed on 6 Nov. 2015 and U.S. Provisional Patent Application Ser. No. 62/269,087, filed on 17 Dec. 2015, U.S. patent application Ser. No. 15/345,452, filed on 7 Nov. 2016, and U.S. patent application Ser. No. 15/383,841, filed 19 Dec. 2016, each of which is hereby incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62492900 | May 2017 | US | |
| 62419317 | Nov 2016 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 15807272 | Nov 2017 | US |
| Child | 16796521 | US |
