This disclosure relates to biodegradable components and more particularly to the extrusion and forming of starch-based biodegradable components, and tooling and processes therefor.
Polystyrene foam is known and used as a packaging material for shipping, household items, cars, and other areas of manufacture and transportation. For instance, polystyrene foam materials are used to prevent damage to manufactured items during transportation, as well as adding stability to packaging during the shipping process.
An example extrusion system includes a die including a circular cross-section disposed about an axis, and a plurality of slits disposed in the die and circumferentially spaced about a periphery of the die. Each of the plurality of slits has a generally rectangular cross-section. A ratio of a number of slits comprising the plurality of slits to a distance between the plurality of slits is between approximately 144:1 and 96:1.
Another example extrusion system comprises a holder configured to hold a thermoformable biodegradable material, and a circular die disposed about an axis and attached to the holder, and a tool configured to force the biodegradable material through the die. The circular die has a plurality of slits circumferentially spaced about a periphery of the die, each of the plurality of slits having a generally rectangular cross-section configured to extrude a generally rectangular sheet of the thermoformable biodegradable material. A ratio of a number of slits comprising the plurality of slits to a distance between the plurality of slits is between approximately 144:1 and 96:1.
An example method of forming a biodegradable component using an extrusion system includes choosing a diameter of a die including a circular cross-section in response to a desired size of a desired extruded article, attaching the die to a holder, the die including a plurality of slits circumferentially spaced about a periphery of the die, each of the plurality of slits having a generally rectangular cross-section, wherein a ratio of a number of slits comprising the plurality of slits to a distance between the plurality of slits is between approximately 144:1 and 96:1, providing a thermoformable biodegradable material to the holder, and moving the thermoformable biodegradable material through the die such that the thermoformable biodegradable material expands after passing through the plurality of slits, and the thermoformable biodegradable material from adjacent ones of the plurality of slits contacts to form a tubular biodegradable component.
Referring to
Each of the plurality of sheets 10 are arranged such that they can be stacked to create a workpiece 30 of biodegradable material, which can be cut, formed, or otherwise manipulated to be used with tooling, as will be described in further detail below. Although the plurality of sheets 10 in this example includes four sheets 10, any number of sheets 10 may be used. In this example, each of the plurality sheets 10 has a generally rectangular profile. However, other profiles may be used depending on the workpiece 30 and/or component to be formed. Each of the plurality of sheets 10 is attached by an adhesive 32 disposed along contacting portions between the plurality of sheets 10. In one example, the adhesive 32 includes a starch-based adhesive or a dextrin-based adhesive. However, other adhesives may be used.
Referring to
In this example, the plurality of slits 44 are equally circumferentially spaced a distance 46 apart about axis A and define a generally rectangular geometric profile. The distance 46 is defined between a first corner 45 and a second corner 47 of adjacent slits at an outer surface 49 of each slit. In this example, the distance 46 is between 0.125 inches and 0.1875 inches. Each of the plurality of slits 44 have a uniform cross sectional shape and a uniform radial thickness 48. In this example, the thickness 48 is between 0.060 inches and 0.120 inches. The plurality of slits 44 may each have a varying thickness 48 and be spaced a varying distance 46 apart in response to a desired extruded article (
The die 40 includes a diameter 59 between 8 inches and 14 inches. The diameter 59 is chosen in response to a desired size of an extruded article 60 (
In a further example, a ratio of the number of slits 44 to the distance 46 between slits 44 is between 144:1 and 96:1.
In one example, adjacent slits 44 of the plurality of slits 44 may be spaced non-uniform distances 46 apart and have non-uniform thicknesses 48 in response to a desired extruded article thickness.
In one example, the number of the plurality of slits 44 is determined based on the rate of extrusion through the plurality of slits 44 and the consistency of supply of thermoformable biodegradable material 50.
The die 40 is attached to the holder 42 (shown schematically) which holds a supply of thermoformable, biodegradable material 50 to be extruded. A tool 52 is in communication with the supply of thermoformable biodegradable material 50 and forces the thermoformable biodegradable material 50 towards die 40 and through the plurality of slits 44. In one example, the tool 52 is a screw.
In this example, the die 40 is heated during the extrusion process to between 300° F. and 600° F. In one example, the die 40 is heated during the extrusion process to 500 ° F. The heat and shaping provided by the die 40 as the thermoformable biodegradable material 50 is extruded through the plurality of slits 44 provides an extruded article (
Referring to
After the extruded article 60 is formed via die 40, a second tool 64 (shown schematically) is used to cut the extruded article 60 along an axis B at a location 64. In one example, the second tool 64 is a knife. In this example, the extruded article 60 is cut once at the location 64 between adjacent facets. However, the extruded article 60 may be cut multiple times at different circumferential locations about the extruded article 60. Location 64 may also vary such that the extrude article 60 may be cut anywhere about the circumference of extruded article 60.
After the extruded article 60 is cut, it can be unrolled such that opposing ends 74a, 74b resulting from cutting the extruded article define ends of a sheet 10 of the plurality of sheets 10. As seen in
The example die 40 with the plurality of slits 44 provides an isotropic sheet 10. That is, whereas a convoluted sheet includes toughs and peaks with inherent weaknesses in performance characteristics, the non-convoluted sheet 10 has no inherent physical weakness at a particular location along a length of the sheet 10 or within a cross-section of the sheet 10, and all surfaces of the sheet 10 may be utilized for the same functions. The example die 40 and plurality of slits 44 provide a sheet 10 that has increased performance characteristics compared to convoluted sheets, including increased load deflection, increased energy absorption, and increased durability. The configuration of the die 40 and the plurality of slits 44 provides extrusion of a sheet 10 which has a uniform cross sectional area, thickness, and density throughout the entire sheet 10 along axis B, and is non-corrugated and non-convoluted.
As seen in
Referring to
In this example, the workpiece 30 has a width 84 of 2.8750 inches and a height 86 of 3.0 inches. In another example, the workpiece 30 has a cross-sectional area of 8 inches2. The configuration of the die 40 and the plurality of slits 44 provides extrusion of a sheet 10 which has a uniform cross sectional area, thickness, and density, and is non-convoluted reduces usage of thermoformable biodegradable material 50 to form workpiece 30 by 50% compared to convoluted sheets. Additionally, the improved performance characteristics of the workpiece 30 formed using the configuration of the die 40 and the plurality of slits 44 allows for a workpiece 30 having a smaller cross-sectional area compared to a workpiece of convoluted and compressed layers, while maintaining similar or improved performance characteristics.
In this example, cavity 80 may be formed using a heated tool (not shown) having a cross sectional profile corresponding to the cross sectional profile of the portion of product 82 to be inserted into cavity 80. In this example, the workpiece 30 has a protective layer 90 attached by an adhesive to opposing sides of the workpiece 30. The protective layer 90 comprises one of cardboard or paper. In one example, the product 82 is a glass component, or other automotive component of manufacture.
Although a preferred embodiment of this disclosure has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this disclosure. For that reason, the following claims should be studied to determine the true scope and content of this disclosure.
This application is a divisional of U.S. patent application Ser. No. 14/667,728, filed Mar. 25, 2015, which claims priority to U.S. Provisional Application No. 61/933,902 filed Jan. 31, 2014.
Number | Date | Country | |
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61933902 | Jan 2014 | US |
Number | Date | Country | |
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Parent | 14667728 | Mar 2015 | US |
Child | 15647816 | US |