Patent Application
20050047687
This invention relates to flexible and foldable bags and more particularly, to bags designed to hold food products such as bread. This invention also relates to methods of manufacturing such bags and apparatuses to implement the methods.
It is known to construct a plastic bag by folding a continuous sheet of a flexible material, such as thermoplastic, over on itself, then making an in-fold at the folded edge, to form a gusset, and then simultaneously cutting and heat sealing the folded sheet along spaced apart transverse lines that are perpendicular to the fold. Each individual bag formed in this manner has an “W” shaped cross section at the gusset. This type of bag is commonly referred to as a “bread bag” and is often used for packaging loaves of bread. The bread loaf is inserted into the bag through an open end that is opposite the gusset. The open end is then tied shut in an appropriate manner to often present what is called the “pony-tail” end of the bag.
When filled with goods, such as a loaf of bread, bags constructed in this manner have, where the each side sealed edge meets the bottom, a triangular shaped pocket folded into the bag. When the bag is not carefully packaged, the triangular shaped pocket may not fold perfectly inside and thus cause the bottom of the bag to deform or wrinkle. This is a particular problem as bread is often stocked on shelves with the bottom facing the consumer and the bottom contains the product identifying information and the supplier's trade-marks and logos. Product information and logos are often printed directly on the bag or affixed using a label. Furthermore, this pocket also makes printing material that wraps around the bottom to the sides of the bag difficult. Generally, the pocket does not provide for a very clean look particularly when viewed from the bottom or from the side as the bag is usually transparent or translucent. Furthermore, since traditional bread bags are often transparent, light incident on the food product can decrease the visual quality of the food.
There is therefore a need for improved flexible bags which solves the above problems and can be efficiently manufactured.
The present invention provides an improved flexible bag that has a clean square bottom and can be efficiently manufactured. The improved bag is particularly suited for containing food stuffs.
According to one broad aspect of the present invention, a bag is provided that has improved presentation and ability to keep food fresh comprising a sheet of flexible, foldable material,
According to another aspect of the invention, a method is provided for manufacturing the bag. The method comprises the following steps:
According to another aspect of the invention, an apparatus is provided to simultaneously make an “V” or “Y” shaped cut and bond resultant edges using heat, comprising:
One advantage of present invention is that a bag with a square and flush bottom provides improved presentation. A square and flush bottom presents an improved surface for affixing labels or printing product information and logos. Furthermore, the bag increases the ease with which one can affix labels or print product information on the bag that wraps around the bottom to the sides. Generally, the bag gives an overall cleaner look.
Another advantage of the present invention is that it alleviates the problem of wrinkling and deforming that occurs when bags of the prior art are not carefully filled since the present invention does not have triangular shaped pockets on the bottom face.
Another advantage of the present invention is that by treating one side of the bag with a metal, such as aluminum, food products packages in the bag will stay fresh longer. Treating one side of the bag with metal also reduces the amount of light incident on the food product thereby maintaining the visual quality of the food.
Another advantage of the present invention is that it can be manufactured easily since the cutting and sealing can be performed in single step. This is due, in part, to the treating of one side of the bag with a metal.
These and other features of the preferred embodiments of the invention will become more apparent in the following detailed description in which reference is made to the appended drawings wherein:
In the following description, numerous specific details are set forth to provide a thorough understanding of the invention. However, it is understood that the invention may be practiced without these specific details. In other instances, well-known structures and/or processes have not been described or shown in detail in order not to obscure the invention. In the description and drawings, like numerals refer to like structures or and/or processes.
The methods of the present invention are claimed and described herein as a series of steps. It should be understood that these methods and associated steps may be performed in any logical order. Moreover, the methods may be performed alone, or in conjunction with other procedures and methods before, during or after such methods and steps set forth herein without departing from the scope and spirit of the invention.
Referring to
Referring generally to
The sheet 210 similarly comprises the top edge 105, bottom edge 106, side edges 103 and the apertures 109 proximal to the top edge. The sheet 210 is folded along the fold line 107 substantially perpendicular to the side edges 103 to define (i) a front side 101 and a back side 102, (ii) an exposed portion 141 proximal to the top edge 105 such that the apertures 109 on the back side 102 are not covered, and (iii) an area of overlap 140 between the front side 101 and the back side 102. Importantly, as shown in
Transversely opposite ends portions of the gusseted bottom edges 108 are angled edges 220 that angle upwards at a predetermined angle 225 and end at side edges 103. The angle 225 can be from 30-60 degrees but is preferably about forty-five degrees. Also, the angled edges 220 preferably end at the side edges 103 at about a gusset height's length from the gusseted bottom edges 108, thus ending about where the fold line 107 meets the side edges 103. The side edges 103 are bonded to each other. The angled edges 220, only of adjacent sheets that have un-treated sides 230 facing each other, are bonded to each other. Therefore, since the angled edges 220 are in the gusset 120 portion of the bag, only those portions of the sheet representing a peak on the “W” shape of the gusset 120 are bonded together.
Referring to
Referring to
According to another aspect of the invention, a method is provided to manufacture a metal coated bag with a flush square bottom. The method comprises the following steps. Coating a flexible sheet with a suitable metal so that one side is treated and the other is un-treated. Folding the sheet along a fold line such that the treated side faces outwards. Creating a gusset of a pre-determined depth by in-folding at the fold line. Making an angular cut, in a “V” shape, on the sheet through the gusset such that the tip of the “V” is positioned at a pre-determined length from the gusseted bottom and the sides of the “V” extend towards and end at the gusseted edge. Bonding the sheet together at adjacent edges of the “V” shaped cut that have un-treated sides facing each other. Cutting along a line starting at the tip of each “V” shape and extending in a direction perpendicular to the fold line and ending at a top edge of the bag and then bonding the resulting edges together. This cutting and bonding is repeated along a length of the sheet, in a direction parallel to the fold line, to manufacture multiple bags.
The sheet can be of any flexible, foldable material, including but not limited to a thermoplastic material. Methods for producing a sheet of thermoplastic material are well known and typically consist of extruding a lay flat tube of thermoplastic material and edge slitting the lay flat tube on both sides to produce 2 layers of film.
Any suitable metal can be used to coat the sheet. Preferably, aluminum is used and methods to coat thermoplastic material using aluminum, such as for potato chip bags, are well known in the art and will not be described here. Coating thermoplastic materials can involve an intermediate treatment to enable the metal to adhere to the material.
Referring to
The cut extending from the corner of the “V” shape is shown as a solid line formed by line segment 900-903. The resultant edges are bonded together. This results in an overall cut in the shape of a “Y”. As generally illustrated by
In a preferred embodiment of the invention, cutting and bonding are performed in a single step. This is possible since the sheet has been treated on one side with aluminum and this side is on the outside of the bag. When the edges are cut, bonding using heat is simultaneously performed. This advantageously only bonds the desired edges together. Cutting the “V” shape while heating the resultant edges will result only in the sheet portions forming the peaks of the “W” being bonded together because only the peaks have un-treated sides facing each other. In contrast, sheets portions forming the valley of the “W” shape will not be bonded together because the edges that face each other have been treated with a metal such as aluminum. With respect to the cut extending from the corner of the “V” shape, the resultant edges will have un-treated sides facing each other. Consequently, the edges will be bonded together as desired.
According to another aspect of the invention, an apparatus 500 is provided to simultaneously make the “V” or “Y” shaped cuts of the method described above. Referring to
The lower plate 508 is disposed over the heating block and comprises a metal stripper plate 510, an insulating plate 509 attached to a top surface of the stripper plate, and springs 503 that allow the lower plate 508 to move in a direction perpendicular to the top surface of the heated block 501. The springs 503 of the lower plate 508 are attached to a ground surface 520, preferably by shoulder bolts 504. The lower plate further comprises a hole the shape of and slightly larger than the blade 502 and disposed to receive the blade 502.
The upper plate 505 is disposed over the lower plate 508 and comprises a clamp plate 506 and a resilient surface 507 on an underside of the clamp plate 506. Furthermore, the upper plate 505 is capable of motion in a direction perpendicular to the top surface of the heated block 501. In some preferred embodiments of the invention, the upper plate is pneumatically driven.
In operation, the blade 502 is heated by the heater block 501. A sheet of material is placed in between the upper plate 505 and the lower plate 508. The upper plate 505 is driven downwards and presses on the lower plate 508. This causes the lower plate 508 to move down and the blade 502 to move through and exit the topside of the hole on the lower plate 508. The exiting blade 502 thus presses against the upper plate 505. This action results in a “V” shaped cut in the material in between the upper plate 505 and the lower plate 508 using the heated blade 502. Since the blade 502 is heated, suitable materials and surfaces will be bonded simultaneously with the cut. In another embodiment of the invention, a “Y” shaped blade is used to produce “Y” shaped cuts.
Although preferred embodiments of the invention have been described herein, it will be understood by those skilled in the art that variations may be made thereto without departing from the spirit of the invention or the scope of the appended claims.
