Patent Application
20250001670
The present technology relates to systems and processes for producing a plurality of preforms having a plurality of temperature profiles, including where such preforms can be subjected to blow molding processes.
This section provides background information related to the present disclosure which is not necessarily prior art.
Various products are distributed in plastic containers, such as containers formed from one or more polymers. Common polymers used to form containers include polyesters, such as polyethylene terephthalate (PET), high and low density polyethylenes (PE), polypropylenes (PP), and polycarbonates (PC), among others. Plastic containers can be made using various blow molding processes including injection blow molding, liquid or hydraulic blow molding, and extrusion blow molding, where such blow molding processes can employ a preform that is expanded by a fluid to form a resultant container.
Injection blow molding can be used to form certain plastic containers in one or more stages and can include use of a stretch rod. In a two-stage injection stretch blow molding process, a polymer can be first molded into a preform using an injection molding process. The preform can include the neck and finish of the container to be formed, which can include threading thereon, and a closed distal end. The preform can then be heated above the polymer glass transition temperature, optionally stretched longitudinally with a stretch rod, and blown using high-pressure gas (e.g., air) into a container conforming to a mold. As the preform is inflated, it elongates and stretches, taking on the shape of the mold cavity. The polymer solidifies upon contacting the cooler surface of the mold and the finished hollow container is subsequently ejected from the mold.
Liquid or hydraulic blow molding can form and fill a container in a single operation. A liquid product can be used to form and fill a polymeric preform within a mold into a resultant container, where the liquid product remains thereafter in the finished container. A heated preform, much like the preform used in injection blow molding, can be placed within the mold, optionally stretched, and rapidly filled using a liquid product instead of a gas to form a container therefrom. Combination of the forming and filling steps can therefore optimize packaging of a liquid product by eliminating the transport of empty containers and time demands related to subsequent filling operations.
Various types of preforms can be used in such blow molding processes. Certain embodiments of preforms include injection-molded, rotationally symmetric preforms that have an elongated, cylindrical, lateral body section, a rounded, closed bottom, and a neck section with an upper opening. Other preforms have be rotationally asymmetric with a varying thickness along an elongate axis to facilitate a material distribution that forms an asymmetric container. In either case, positioned proximate to the opening, there can be an outer threaded finish section, which can be delimited toward a bottom thereof by a collar or the like. The threaded finish section can be preserved during blow molding of the preform where the finish can form a thread for a screw cap of a finished beverage container, for example. The remaining portion of the preform, in contrast, can be deformed and stretched during the blow molding process. Preforms can be heated to predefined temperatures in order to enable blow molding in the desired manner. Heating can be performed by various means, including infrared radiation using an infrared oven, to effect defined and/or uniform temperature control of the preforms.
In particular, the polymeric material of the preform (e.g., PET) can be of such a nature that the polymer can strain harden as the polymer is stretched. Forming temperature during the blow molding process can therefore be a determinative factor in the resultant container. The strain hardening effect can be taken into consideration in the production of PET containers for the purpose of controlling and optimizing wall thickness distribution. Depending on the production process, it can be possible to apply heat via infrared radiation in such a way that the preforms are heated according to a temperature profile. In this manner, the warmer sections of the preform can be deformed with priority over other parts as long as is required for the stretching resistance resulting from strain hardening to become greater than the resistance of the adjacent cooler sections, for example. The temperature profile can be uniformly distributed around the circumference of the preforms and can vary process-dependently along the longitudinal axis of the preforms. In order to apply the desired temperature profile to the preforms, use a number of heating zones can be used, for instance up to nine or more zones. It is possible to control the plurality of different heating zones individually, whereby the selected setting is maintained constant over a longer period of operating the heating apparatus.
Preforms of different construction can require different heating regimens in preparation for blow molding into resultant containers. For example, preforms of different sizes, shapes, thicknesses, formed of or including different polymers or polymer combinations, layers, and the like can each have a predetermined temperature profile optimized for a particular blow molding process. Certain examples include different heating regimens for effecting different temperature profiles for PET preforms versus PP preforms. Other examples include different heating regimens for effecting the same temperature profile, but where the preforms have different characteristics that require different regimens to achieve the same temperature profile: e.g., preforms formed of the same material but having different thicknesses. Accordingly, various heating parameters can be tailored for particular preforms, including the number of heating zones, the temperature of certain heating zones, the exposure time to certain heating zones, and the like.
A blow molding system can often include a preform heating means in close proximity thereto, where heated preforms can be passed to a mold in short order and formed into resultant containers before a desired temperature profile of the preforms changes. A travel path of a preform through an infrared oven, for example, can be tailored to generate a predetermined temperature profile in a given preform. However, if a condition of the blow molding system and/or process is changed, it can be necessary to change the preform path or heating means to adapt to a new temperature profile for a given preform. Changes in blow molding conditions can include the use of another preform type, a change in the mold, changes in blow molding parameters, and the like. Accordingly, it can be difficult to adapt a blow molding system and/or process to changing conditions that require changes in preform temperature profiles while maintaining continuous or high throughput production of containers. Oftentimes, one or more settings may need to be changed, one or more new equilibriums reached, and one or more physical parameters may need to be adapted in the blow molding system in order to accommodate preforms having different characteristics.
Absent appropriate temperature control, a heated preform may have an improper material distribution and/or expansion during a blow molding operation and the resulting container may rupture (or “blowout”) or otherwise fail an aesthetic inspection. For refined gas blow molding processes, it can be expected that from about 1500 to about 2500 containers per one million gas blow molded container will suffer from a blowout. The expected blowouts from a liquid blow molded container is roughly the same. In the instance of liquid blow molding, a blowout will result in more than escape of air and will result in an escape and possible waste of the liquid product to fill the container. When the blow molding liquid is water, a blowout may result in little more than wasted water and negligible down time to allow the blow molding equipment to dry. When the blow molding liquid is a petroleum product, medicine, or cosmetic, for example, a blowout can result in a significant of time due to cleaning procedures required to render the blow molding equipment once-again operational and can result in wasted and unusable product, each of which alone may create a significant economic impact on the blowing molding process and product cost but combined may render the liquid blow molding process economically unfeasible for packing the product. It would be desirable to develop a method of blow molding that would reduce the expected blowouts for a blow molding operation (liquid or gas) to about 25 blowouts per million containers formed.
In consideration of these issues, the present technology provides a method of measuring and monitoring preforms during a heating thereof to minimize blowouts during a blow molding operation, where the resulting blow molding operation can be maintained in a continuous or high throughput fashion.
Concordant and congruous with the present invention, a method of measuring and monitoring preforms during a heating thereof to minimize blowouts during a blow molding operation has surprisingly been discovered.
In an embodiment of the invention, a method for heating a preform, the method comprises the steps of providing a plurality of preforms suitable for blow molding: inspecting each preform to identify at least a material from which the preform is formed: heating each preform: measuring the temperature of at least a portion of each preform along its longitudinal axis and around its circumference: further heating each preform: further measuring the temperature of at least a portion of each preform along its longitudinal axis and around its circumference to generate a temperature profile: comparing the temperature profile from the further measuring step to a standard temperature profile of each of the plurality of preforms: and blow molding any preform that has an acceptable temperature profile based on the comparing step.
In another embodiment of the invention, a method for heating a preform, the method comprises the steps of providing a plurality of preforms suitable for blow molding: inspecting each preform to identify at least a material from which the preform is formed: heating each preform: measuring the temperature of at least a portion of each preform along its longitudinal axis and around its circumference: further heating each preform: further measuring the temperature of at least a portion of each preform along its longitudinal axis and around its circumference to generate a temperature profile: comparing the temperature profile from the further measuring step to a standard temperature profile of one of the plurality of preforms: and blow molding any preform that has an acceptable temperature profile based on the comparing step, recycling any preform that does not have an acceptable temperature profile based on the comparing step, or reheating any preform that does not have an acceptable temperature profile based on the comparing step.
In another embodiment of the invention, a method for heating a preform, the method comprises the steps of providing a plurality of preforms suitable for blow molding: inspecting each preform to identify at least a material from which the preform is formed: heating each preform: measuring the temperature of at least a portion of each preform along its longitudinal axis and around its circumference: further heating each preform: further measuring the temperature of at least a portion of each preform along its longitudinal axis and around its circumference to generate a temperature profile: compiling the measured temperatures of the at least a portion of each preform during the further measuring step: converting the compiled measured temperatures into a three-dimensional thermal image representing the measured temperatures of the at least a portion of the preform: further converting the three-dimensional thermal image into a two-dimensional thermal image representing the portion of the preform measured along its longitudinal axis and around its circumference in the further measuring step: comparing the two-dimensional thermal image from the further converting step to a standard two-dimensional thermal image corresponding to one of the plurality of preforms: and blow molding any preform that has an acceptable temperature profile based on the comparing step, recycling any preform that does not have an acceptable temperature profile based on the comparing step, or reheating any preform that does not have an acceptable temperature profile based on the comparing step.
The above, as well as other advantages of the present invention, will become readily apparent to those skilled in the art from the following detailed description of a preferred embodiment when considered in the light of the accompanying drawings in which:
The following description of technology is merely exemplary in nature of the subject matter, manufacture and use of one or more inventions, and is not intended to limit the scope, application, or uses of any specific invention claimed in this application or in such other applications as can be filed claiming priority to this application, or patents issuing therefrom. Regarding methods disclosed, the order of the steps presented is exemplary in nature, and thus, the order of the steps can be different in various embodiments, including where certain steps can be simultaneously performed. “A” and “an” as used herein indicate “at least one” of the item is present: a plurality of such items can be present, when possible. Except where otherwise expressly indicated, all numerical quantities in this description are to be understood as modified by the word “about” and all geometric and spatial descriptors are to be understood as modified by the word “substantially” in describing the broadest scope of the technology. “About” when applied to numerical values indicates that the calculation or the measurement allows some slight imprecision in the value (with some approach to exactness in the value: approximately or reasonably close to the value: nearly). If, for some reason, the imprecision provided by “about” and/or “substantially” is not otherwise understood in the art with this ordinary meaning, then “about” and/or “substantially” as used herein indicates at least variations that can arise from ordinary methods of measuring or using such parameters.
All documents, including patents, patent applications, and scientific literature cited in this detailed description are incorporated herein by reference, unless otherwise expressly indicated. Where any conflict or ambiguity can exist between a document incorporated by reference and this detailed description, the present detailed description controls.
Although the open-ended term “comprising,” as a synonym of non-restrictive terms such as including, containing, or having, is used herein to describe and claim embodiments of the present technology, embodiments can alternatively be described using more limiting terms such as “consisting of” or “consisting essentially of.” Thus, for any given embodiment reciting materials, components, or process steps, the present technology also specifically includes embodiments consisting of, or consisting essentially of, such materials, components, or process steps excluding additional materials, components or processes (for consisting of) and excluding additional materials, components or processes affecting the significant properties of the embodiment (for consisting essentially of), even though such additional materials, components or processes are not explicitly recited in this application. For example, recitation of a composition or process reciting elements A, B and C specifically envisions embodiments consisting of, and consisting essentially of, A, B and C, excluding an element D that can be recited in the art, even though element D is not explicitly described as being excluded herein.
As referred to herein, disclosures of ranges are, unless specified otherwise, inclusive of endpoints and include all distinct values and further divided ranges within the entire range. Thus, for example, a range of “from A to B” or “from about A to about B” is inclusive of A and of B. Disclosure of values and ranges of values for specific parameters (such as amounts, weight percentages, etc.) are not exclusive of other values and ranges of values useful herein. It is envisioned that two or more specific exemplified values for a given parameter can define endpoints for a range of values that can be claimed for the parameter. For example, if Parameter X is exemplified herein to have value A and also exemplified to have value Z, it is envisioned that Parameter X can have a range of values from about A to about Z. Similarly, it is envisioned that disclosure of two or more ranges of values for a parameter (whether such ranges are nested, overlapping or distinct) subsume all possible combination of ranges for the value that might be claimed using endpoints of the disclosed ranges. For example, if Parameter X is exemplified herein to have values in the range of 1-10, or 2-9, or 3-8, it is also envisioned that Parameter X can have other ranges of values including 1-9, 1-8, 1-3, 1-2, 2-10, 2-8, 2-3, 3-10, 3-9, and so on.
When an element or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it can be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers can be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to” or “directly coupled to” another element or layer, there can be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.
Although the terms first, second, third, etc. can be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms can be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.
Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, can be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms can be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device can be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
As shown in
With respect to the preform 12,
In the system 10, each preform 12 is provided at an entrance of in-feed station E by way of a mag-lev track, rail, or other transport mechanism (not shown). The preforms 12 are then individually placed onto a conveyor 28, which transports the preforms 12 through the system 10, as detailed hereinbelow, and ultimately to an exit S of the system 10 for further processing steps 30. As discussed in further detail below, the further processing steps 30 may include transporting the preform 12 for one of re-entry into the entrance E for additional heating, rejection and recycling, or to a blow mold loading station (not shown) for forming the preform 12 into the container. It is understood that the blow molding step may be either reheat stretch blow molding process using a compressed gas, or a liquid blow molding process wherein a compressed liquid that is the ultimate contents of the container are used to form the container from the preform 12.
Each preform 12 enters the system 10 (at ambient temperature) disposed on a spindle 32 (as shown in
After inspection and measuring by the camera 14, each preform 12 is transported via the conveyor 28 through a first portion 33 of the system 10 having a series of heating means 18. The heating means 18 may be an infrared oven, for example, or any suitable heating means as known by one of ordinary skill in the blow molding art. Direct and/or indirect (e.g., reflected) thermal energy can be applied by the heating means 18. Multidirectional application of thermal energy can be used as well as where preforms 12 themselves are moved, spun, or rotated about various thermal radiation sources in the various heating means 18. Any number of heating means 18 may be utilized, as desired, but, as shown in
As shown in
As noted above, the temperatures of the preform 12 are tabulated by the computer 34. The temperatures measured are then plotted against the position of the measurement on the preform 12, as shown in a graph 44 in
By creating the two-dimensional thermal image 40, temperature measurements of each heated preform 12 may be readily and easily ascertained before the preform 12 is transferred to the blow molding station and molded into the final container. In some instances, the thermal images 38, 40, and/or the graph 44 may indicate that a preform 12 has “cool regions” 46 or “warm regions” 48. Such regions 48, 48 may result in blowouts during blow molding, thus requiring remedial action during the heating of the preform 12. Because the exact location of such regions 46, 48 can be pinpointed by observance and analysis of the thermal images 38, 40, and/or the graph 44, remedial action can be taken to ensure proper heating of the preform 12 to minimize blowouts during blow molding thereof into the container. The remedial action may include adjustment of one or more of process parameters and settings of the system 10, including adjustment of the heating means 16 or specific heating elements 36, to increase or decrease the temperature of any portion of the preform 12 (e.g., the regions 46, 48), as desired, so that subsequent preforms have a different and acceptable temperature profile to minimize blowouts during blow molding. Additional remedial actions include, for example, upwardly or downwardly adjusting the spin rate of the spindle 32 upon which each preform 12 is disposed, or increasing or decreasing the residence time of the preform 12 (or speed of the conveyor 28) within the system 10, and/or cooling airflow within the system 10 may be increased or decreased.
Once each preform 12 is inspected and measured by the second camera 16, the conveyor 28 transports each preform 12 to a second portion 35 of the system 10 to a series of additional heating means 50. Like the heating means 18, the heating means 50 may be an infrared oven, for example, or any suitable heating means as known by one of ordinary skill in the blow molding art. Direct and/or indirect (e.g., reflected) thermal energy can be applied by the heating means 50. Multidirectional application of thermal energy can be used as well as where preforms 12 themselves are moved, spun, or rotated about various thermal radiation sources in the various heating means 50. Any number of heating means 50 may be utilized, as desired, but, as shown in
As each preform 12 passes the heating means 50, each preform 12 is rotated on its spindle 32 thus being heated by the heating means 18 until each preform 12 reaches the third camera 17. As shown in
In use, the images and/or information obtained from the first camera 14 are processed by the computer 34 to determine the thermal treatment appropriate for each preform 12 is to receive from the heating means 18. For example, the first camera 14 may identify individual preforms formed from different materials or having different sizes corresponding to resulting containers having different volumes. Accordingly, each preform 12 may require its own specific thermal treatment from the heating means 18, and/or the first camera 14 may detect an unacceptable number of inclusions or other unacceptable issues with a particular preform and signal the system 10 via the computer 34 or the process controller to reject that preform and remove it for recycling or destruction. Once each preform 12 receives its thermal treatment from the heating means 18, data is gathered for each preform 12 by the second camera 16. The computer 34 compares the data for each preform 12 as received from the first camera 14 and to data received from the second camera 16 to ensure that the thermal treatment was appropriate and acceptable for the given specifications (e.g., dimensions and/or material) of the preforms 12. In this way, it can be ensured that each preform 12 enters the second portion 35 of the system for additional heat treatment by the heating means 50 at a consistent temperature and/or temperature profile regardless of the ambient conditions of the system 10 or starting conditions of the preform 12 upon entry into the entrance E of the system 10.
The computer 34 or the process controller may cause adjustments to the first portion 33 of the system 10 to ensure subsequent preforms 12 of similar specification receive an appropriate thermal treatment by, for example, increasing or decreasing the intensity of the heating means 18, upwardly or downwardly adjusting the spin rate of the spindle 32 upon which each preform 12 is disposed, or increasing or decreasing the residence time of the preform 12 (or speed of the conveyor 28) within the first portion 33 of the system 10, and/or cooling airflow within the first portion 33 of the system 10 may be increased or decreased. The computer 34 and/or the process controller will make adjustments to the first portion 33 of the system 10, as necessary, based on a comparison of images from the cameras 14, 16 and/or data from the cameras 14, 16 with respect to each preform 12. By ensuring that the thermal treatment for each preform 12 is appropriate and acceptable prior to the preform 12 being subjected to a blow molding operation (i.e., the further processing steps 30), blowouts of the preform(s) 12 are minimized and cost savings may be realized.
Furthermore, once each preform 12 receives a second thermal treatment in the second portion 35, the images 38, 40 and/or graphs 42 generated from the third camera 17 for each preform 12 may be compared by the computer 34 against a catalog, database, table, or collection of images (e.g., heat maps) and/or data points and/or graphs that correspond to a predetermined, acceptable temperature profile (separately or collectively, a “standard temperature profile”) of each preform 12 of a particular material or dimension. In this way, the computer 34 can compare data for each preform 12 that passes the third camera 17 against the acceptable temperature profile of a preform of similar dimensions and/or materials to ensure that the temperature profile of each preform 12 is optimized, thereby militating against blowouts of the preform(s) 12 during the further processing steps 30.
This comparison made after each preform 12 is measured by the third camera 17 may be in the form of a comparison of an acceptable thermal image for a given preform of defined dimensions and/or materials to a thermal image, such as the two-dimensional image 40 from the third camera 17, of each preform 12 processed within the system 10: a comparison of acceptable tabulated thermal data from the third camera 17 to tabulated data of each preform 12 processed within the system 10. The comparison may also be a comparison of an acceptable graph corresponding to an acceptable temperature profile to each graph similar to the graph 42 from data from the third camera 12 of each preform 12 processed within the system 10.
By comparing thermal data and/or images of each preform 12 processed within the system 10 to a known, constant, acceptable set of thermal data and/or images, thermal treatment of preforms therethrough may be readily reproduced anywhere in the world independent of the ambient temperature of the system 10, the ambient conditions of the system 10, or the starting temperature or conditions of the preforms. Regardless of where the system 10 is located, each processed preform 12 will be observed and identified by the first camera 14, subjected to an appropriate thermal treatment corresponding to the material and/or dimensions of the preform 12 by the heating means 18 in the first portion 33: have its temperature profile obtained by the second camera 16 to ensure its starting temperature prior to entering the second portion 35 is acceptable: subjected to an appropriate thermal treatment by the heating means 50 in the second portion 35: and then have its temperature profile compared to an acceptable temperature profile by the computer 34. After the comparison, each of the preforms 12 will either align with the known, acceptable temperature profile (or within an acceptable deviation therefrom) transported for blow molding into the container, or each of the preforms 12 will deviate from the known, acceptable temperature profile and be either transported for additional thermal treatment, or rejected and recycled (collectively, the further processing steps 30). The further
By ensuring that each preform 12 has received an acceptable thermal treatment by the system 10 before being transported to the exit S by comparing each preform 12 to known, acceptable standard data, unacceptable preforms may be discarded or re-heat treated before blowouts of each preform 12 during a blow molding thereof can be minimized. For unacceptably heated preforms 12 as determined in the comparison to images generated from the third camera 17, the computer 34 or the process controller may cause adjustments to the second portion 35 of the system 10 to ensure subsequent preforms 12 of similar specification receive an appropriate thermal treatment by, for example, increasing or decreasing the intensity of the heating means 50, upwardly or downwardly adjusting the spin rate of the spindle 32 upon which each preform 12 is disposed, or increasing or decreasing the residence time of the preform 12 (or speed of the conveyor 28) within the second portion 35 of the system 10, and/or cooling airflow within the second portion 35 of the system 10 may be increased or decreased.
Once each of the preforms 12 is deemed acceptable, each preform 12 is transported to one or more systems (not shown) for blow molding the container from each preform 12. In particular, the blow molding system can include a mold (not shown) configured to receive each preform 12 and a means for delivering a pressurized fluid to a preform received in the mold to expand the preform into the container conforming to an interior surface of the mold. The pressurized fluid can be a gas (e.g., air) or can be a liquid (e.g., a product intended to remain within the resultant container). In a process where each of the preforms 12 is formed from different materials and/or has different dimensions, a transport mechanism may selectively transport each of the preforms 12 to different blow molding systems for forming a multitude of containers. That is, the present technology further contemplates sequential production of various containers derived from preforms heated to different temperature profiles, including preforms of different construction that require different heating regimens and different comparisons to different known, acceptable temperature profiles in preparation for blow molding into resultant containers: e.g., preforms of different sizes, shapes, thicknesses, formed of or including different polymers or polymer combinations, layers, etc.
Benefits and advantages of the present technology can include the following aspects. Juxtaposition and metering of multiple sizes and materials of preforms within the same system (e.g., the system 10). Selective transfer of preforms and controlled dispensing between and from the multiple heating means provides unique ways to handle different preforms and allows flexible stock-keeping unit (SKU) management. For example, the system can include one or more bar code readers to track loading positions of preforms as they enter the system from one or more loaders and are subjected to certain travels through pathways including portions of one or more heating means or differing speeds and/or residence times. The ability of flexibly treat a mix of multiple types of preforms further allows blow molding to be maintained in a continuous or high throughput fashion.
Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments can be embodied in many different forms, and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. Equivalent changes, modifications and variations of some embodiments, materials, compositions and methods can be made within the scope of the present technology, with substantially similar results.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2021/055815 | 6/29/2021 | WO |
