Molding method for manufacturing chiral parts

Abstract

A method is disclosed that enables performing a preform charge suitable for fabricating chiral parts and their mirror images using a single preform charge jig. This method utilizes a preform charge having a flat planar shape, unlike the near-net shape preform charge used in the applicant's prior methods. Two identical instances of the preform charge are being fabricated from the preform charge jig. The first instance of the preform charge is placed in a first orientation within a first compression mold to fabricate a first part. The second instance of the preform charge is placed in a second orientation within a second compression mold to fabricate a second part. The second orientation is obtained by rotating the second instance of the flat planar preform charge 180° with respect to the first orientation about an axis parallel to the reflection axis of the first and second instances of the preform charge.

Description

Technical Field

[0001] [Statement of Related Applications] This specification claims priority to U.S. Provisional Patent Application No. 63 / 349,921, filed on June 7, 2022, the content of which is incorporated herein by reference.

[0002] The present invention relates to molding materials, and more particularly, to a method and apparatus for molding fiber-reinforced composite material parts, and fiber-reinforced composite parts manufactured using the method and apparatus.

Background Art

[0003] Composite materials are those in which fibers are embedded in a supporting matrix material and are used to produce strong yet lightweight parts. These composite materials have an attractive combination of properties and offer significant manufacturing, performance, and economic advantages.

[0004] The present applicant has disclosed the use of a preform charge as a supply structure for a compression molding process for manufacturing fiber composite parts. The preform charge includes an arrangement of fiber bundle-based preforms. Each preform is composed of a bundle of co-aligned resin-impregnated fibers and is typically supplied from a towpreg or from the output of a resin impregnation line. In addition to being cut to a desired size, each preform is usually specially shaped. This provides an arrangement of the preform that conforms to the contour of the mold cavity in which the preform is placed and provides a desired fiber arrangement throughout the mold. This alignment is maintained in the final part, resulting in a part with excellent mechanical properties.

[0005] Preform charging is typically done with a special fixture. The fixture has a structure suitable for arranging the preforms in a typical three-dimensional shape, which is usually very close to the shape / size of the part to be molded ("near-net shape"). The fixture can include, for example, a plurality of cleats (for defining the arrangement of the preforms) and a clamp for fixing the arranged preforms. In some other embodiments, the fixture includes a cavity that specifies how the preforms are arranged and a clamp for fixing. The preforms typically have a circular / elliptical cross-section and are typically stacked (to provide a three-dimensional shape), so the clamp stabilizes / fixes the stacked ones and provides a minimum at the lower front as described below.

[0006] After being properly arranged by the fixture, the plurality of preforms are "tacked" together. The term "tacking" refers to heating to the softening point (not the melting point) to effectively join the preforms. A single structure is formed by tacking, but the individual preforms retain the characteristics of their original form. In some cases, a minimal compression such as supplied by the clamp is applied to the tacking operation. The resin in the preform is not heated until it liquefies (the preform is typically heated to a temperature higher than the heat distortion temperature of the resin but lower than the melting point), and the pressure applied is typically low (less than 100 psig and in some cases not more than the "gravity" acting on the preform), so the preform charge is not fully consolidated and thus cannot function as a finished part. However, when joined in this way, the preforms do not move, thereby maintaining the desired geometry and specific alignment of each preform in the assembly. See, for example, Patent Document 1 and Patent Document 2 incorporated herein by reference.

[0007] Preform charging offers many advantages, but its production requires the design, manufacture, and use of fixtures for specific preform charging. For certain types of finished parts, especially those that require two separate molds, problems can arise in the use of preform charging because the molds are chiral.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Patent Document 7

Patent Document 8

Summary of the Invention

Problems to be Solved by the Invention

[0009] Chirality is the property of asymmetry. An object is "chiral" if it cannot be superimposed on its mirror image. Examples of chiral structures include, among others, certain anatomical features such as the human hand, foot, and ear.

[0010] The following example shows the problems caused by chiral parts. Assume that a manufacturer has to provide a fiber composite footbed for sneakers. Different footbeds are required for the left and the right sneakers. Of course, two different molds are needed to create these two footbeds. In a conventional compression molding process, feed constituents, which are usually multiple sheets of fiber and resin, are placed one by one into each mold that forms the "lay-up" where the part is molded. No preform charge is used and no preform charge tooling is required.

[0011] However, the applicant's process uses a preform charge that is carried out before the molding operation. In the example of the fiber composite footbed, two different preform charge tools are required. One is the first preform charge tool for preforming the left footbed, and the other is the second preform charge tool for preforming the right footbed. Therefore, the use of a preform charge for such parts, along with the associated costs, requires the design and manufacture of two preform charge tools. Also, in the case of footwear, consider that the footbed has to be made in as many different sizes as the sneakers are sold. If the sneakers are offered in 10 different sizes, 20 preform charge tools (two for each size) are required.

[0012] Although a preform charge can be used as a feed constituent for manufacturing such a pair of chiral parts, it would be beneficial to do so via a preform charge manufacturing process that does not require two preform charge tools. Means for Solving the Problems

[0013] Embodiments of the present invention avoid the above problems, thereby improving manufacturing efficiency, reducing design and tooling requirements, and thus reducing costs. More specifically, some embodiments of the present invention enable a single preform charge tooling to perform a preform charge suitable for fabricating chiral parts and their mirror images. Non-limiting examples of chiral parts fabricated via embodiments of the present invention are a "left" footbed (left sneakers, shoes, etc.) and its mirror image part, a "right" footbed (right sneakers, shoes, etc.).

[0014] As described in the Background section, consider again the fabrication of a fiber composite footbed. A right footbed and a left footbed are required. The underside of a human foot is contoured, and thus the footbed must be correspondingly contoured. The preform charges of the present applicant have heretofore been formed as near-net-shape structures. As a result, using this conventional approach, the preform charge for forming the footbed is contoured to match the contour of the final part (e.g., the arch, etc.).

[0015] For example, assume a preform charge tooling is fabricated to perform a preform charge for forming a right footbed. Due to the contoured nature of the "right" preform charge, it cannot simply be "flipped" to perform a preform charge suitable for forming a left footbed. This problem can be visualized by "mentally" flipping the right foot over the left foot. The toes of the right foot are on top of the corresponding toes of the left foot (the toes are in the appropriate position for fabricating the left footbed by this flipping operation), but the bottom (contoured surface) of the right foot becomes upward instead of downward as would be required.

[0016] According to this teaching, this problem is solved by performing a preform charge from a single preform charge tool for forming both a chiral part and its mirror image part during molding. An important feature of the preform charge is its flat planar shape, which is unusual since the applicant's preform charges typically have a near-net shape. Rotating a preform charge having an orientation for molding the right footbed about an axis parallel to the reflection axis of the left and right footbed pair results in a mirror image orientation that enables the left footbed to be molded using that preform charge.

[0017] According to an exemplary embodiment, a method for fabricating a chiral part and its mirror image and performing a preform charge suitable for contouring the part, the method comprising: - designing a pair of parts, wherein the parts to be fabricated include continuous fibers as much as possible across the major dimensions of the parts; - projecting the contoured surface of the first part onto a flat surface, using the shape projected onto the flat surface as a basis for designing the layout of the preform to be used for performing the preform charge; - calculating the expected gaps that result from pressing the flat layout of the preform against the contoured surface (during the molding operation, etc.); - designing a flat preform layout that conforms to the projection of the contoured surface onto the flat surface and adding a compensatory preform (by pressing the flat layout against the contoured surface during molding) as needed to fill the resulting gaps; - placing the preform layout in a preform charge tool; - temporarily fixing the preforms to each other, thereby performing a first (flat planar) preform charge; - Repeating the previous two operations to perform a second (flat planar) preform charge.

[0018] To form a chiral part and its mirror image: - The first preform charge is placed in a mold to form the first part and then compression molded to form the first part. - The second preform charge is "flipped" or rotated 180 degrees about an axis parallel to the "axis of reflection". In this context, the axis of reflection is the axis about which the desired mirror image is produced. - The second preform charge is placed in a mold to form the second part in the reverse / rotation direction and then compression molded to form the second part.

[0019] In some embodiments, embodiments of the present invention provide a method for fabricating a first contoured part and a second contoured part, where the first and second contoured parts are in a mirror image relationship with each other, exhibit chirality, and cannot be superposed, and the method includes producing a first instance of a flat planar preform charge via a preform charge jig; placing the first instance of the preform charge in a first mold for use in forming the first contoured part, wherein the first instance of the preform charge has a first orientation within the first mold; compression molding the first contoured part; producing a second instance of the preform charge via the preform charge jig, wherein the second instance is identical to the first instance; Placing the second instance of the preform charge in a second mold for use in forming the second contoured part, wherein the second instance of the preform charge has a second orientation within the second mold, and the second orientation is centered about an axis parallel to the axis of reflection of the first instance and the second instance of the preform charge, and is obtained by rotating the second instance of the preform charge 180 degrees with respect to the first orientation; Compression molding the second contoured part.

[0020] In some embodiments, embodiments of the present invention provide a method for manufacturing left and right footbeds for footwear, where the left and right footbeds are mirror images of each other, exhibit chirality, and cannot be superimposed, and the method includes: Producing a first instance of a flat planar preform charge having a shape corresponding to a right foot via a preform charge jig; Placing the first instance of the preform charge in a first mold for forming a right footbed in a first orientation; Compression molding the first instance of the preform charge to form the right footbed; Producing a second instance of the flat planar preform charge via the preform charge jig, wherein the second instance has a shape corresponding to a right foot; Placing the second instance of the preform charge in a second mold for forming a left footbed in a second orientation, wherein the second orientation is a mirror image of the first orientation; Compression molding the second instance of the preform charge to form the left footbed.

[0021] In some embodiments, embodiments of the present invention provide a method for fabricating left and right footbeds for footwear, where the left and right footbeds are mirror images of each other, exhibit chirality, and cannot be superposed, and the method comprises: fabricating a first instance of a flat planar preform charge having a shape corresponding to a left foot via a preform charge jig; placing the first instance of the preform charge in a first mold for forming a left footbed in a first orientation; compression molding the first instance of the preform charge to form the left footbed; fabricating a second instance of the flat planar preform charge via the preform charge jig, the second instance having a shape corresponding to a left foot; placing the second instance of the preform charge in a second mold for forming a right footbed in a second orientation, the second orientation being a mirror image of the first orientation; compression molding the second instance of the preform charge to form the right footbed. BRIEF DESCRIPTION OF THE DRAWINGS

[0022]

Figure 1

Figure 2

Figure 3A

Figure 3B

Figure 4

Figure 5

Figure 6A

Figure 6B

Figure 7

DETAILED DESCRIPTION OF THE INVENTION

[0023] The following terms are defined for use in this description and the appended claims: - “Fiber” means an individual strand of material. A fiber has a length much greater than its diameter. - “Fiber bundle” means a plurality (typically a multiple of 1000) of co-aligned fibers. - “Stiffness” in the context of a material means the resistance to bending as measured by Young's modulus. When used in connection with a spring or spring assembly, “stiffness” means the resistance to displacement from an unextended / uncompressed state. - “Tow” means a bundle of fibers (i.e., a fiber bundle), and these terms are used interchangeably herein unless otherwise specified. Tows are typically available in thousands of fibers such as 1K tow (1000 fibers), 4K tow (4000 fibers), 8K tow, etc. - "Prepreg" means fibers impregnated with resin. - "Towpreg" means a bundle of fibers (i.e., tows) impregnated with resin. - "Preform" means a plurality of co-aligned, resin-impregnated segments of fibers, typically of the same length. The segments are cut to a specific length and often formed into a specific shape suitable for the particular part to be molded (e.g., bent, twisted, etc.). Preforms are usually supplied from towpregs (i.e., the towpregs are cut to the desired length), but can also be supplied from another source of co-aligned, unidirectionally aligned fibers (e.g., from a resin impregnation process, etc.). The preform preferably has a cross-section that is substantially circular or elliptical, but does not necessarily have to be so. The applicant's use of the term "preform" specifically excludes (i) tapes / ribbons, (ii) sheets of fibers, and (iii) molded pieces of any size of laminates. The modifiers "fiber-bundle-based" or "aligned-fiber" emphasize the nature of the applicant's preforms and are placed in front of the word "preform" in this specification to distinguish it from prior art preforms, which are typically in the form of shapes cut from tapes / ribbons, sheets, or fiber sheets. - "Preform charge" means an assemblage of preforms that are at least loosely bound (i.e., temporarily fixed) together to maintain their positions relative to each other. A preform charge can include fibers of form factors other than fiber bundles and can include various passive or active inserts. The preform charge is not fully consolidated. - "Preform layup" means the arrangement of individual preforms formed by placing each preform into a mold cavity one by one. Preform layup is distinguished from preform charge, in which case the preforms are at least loosely joined together and the aggregate is usually formed outside the mold cavity. - When used to refer to two different resin materials, "compatible" means that the two resins mix and bond with each other. - "Compression molding" is a molding process in which heat and pressure are applied to the feed components. These components are typically placed in a female mold part having a mold cavity. When the required amount of feed components is placed in the female mold part, a second mold part (male mold part) is joined to the female mold part to close the mold cavity. The male mold part usually extends into the female mold part and includes features that engage the feed components therein. In the applicant's method, the pressure applied to the feed components is typically in the range of about 1000 psi to about 5000 psi, and the temperature, which is a function of the resin used, is typically in the range of about 150 °C to about 400 °C. When the temperature of the resin exceeds its melting temperature due to the applied heat, the resin is no longer solid and flows. Next, the resin conforms to the mold shape through the applied pressure, whereby the feed components are consolidated and a nascent part with very small voids is obtained. The elevated pressure and temperature are typically maintained for several minutes. After this compression molding protocol is completed, the mold is cooled and removed from the pressure source. The completed molded article is removed from the mold. - "Consolidate", "consolidating", or "consolidation" means, in this context, that in a group of fibers / resins such as multiple preforms, voids are removed as much as possible and are acceptable as the final part. The supply structure loses its unique or individual identity, and the previously existing boundaries between adjacent preforms are lost. This requires a fairly high pressure, either by gas pressurization (or vacuum), or by application of mechanical force (e.g., rollers, etc.), and high temperature (to soften / melt the resin). - "Partial consolidation" means, in this context, that in the grouping of fibers / resins, voids are not removed to the extent required for the final part. As an approximation, full consolidation requires a pressure that is one to two orders of magnitude higher than partial consolidation. Further, as a very rough general rule, to consolidate a fiber composite material to about 80% of full consolidation, only about 20% of the pressure required to obtain full consolidation is needed. - "Neat" resin or other matrix material means that the resin / matrix material does not contain reinforcing fibers. - "About" or "Substantially" means ±20% with respect to the recited numerical or nominal value. - Other definitions may be provided elsewhere in this specification, in the context.

[0024] It should be understood that any numerical range described in this specification is intended to include all sub-ranges subsumed therein. For example, the range "1 to 10" is intended to include all sub-ranges between (and including) the recited minimum value of about 1 and the recited maximum value of about 10, i.e., having a minimum value equal to or greater than about 1 and a maximum value equal to or less than about 10. By way of non-limiting example, the recited range of "1 to 10 μm" includes "5 to 8 μm", "1 to 4 μm", "2 to 9 μm", etc.

[0025] Supply Component: The basic supply component used in the methods disclosed herein is a fiber bundle-based preform (hereinafter, "preform"). The preform is typically "formed" from tows, but may also be supplied from the output of a resin impregnation line. To form a preform from tows (or the output of a resin injection line), the tows are cut into segments of a desired size and often shaped similarly (e.g., bent, etc.). Each preform typically contains thousands of co-aligned resin injection fibers in multiples of 1000 (e.g., 1k, 10k, 24k, etc.). The preform can have any suitable cross-sectional shape (e.g., circular, elliptical, triangular, polygonal, etc.), but is most typically circular or elliptical.

[0026] The individual fibers within the preform can have any diameter and are typically in the range of 1 to 100 microns, but not necessarily so. The individual fibers can have any length specific to the application, which results from the cutting operation to produce the associated preform. The individual fibers can include, but are not limited to, an external coating such as sizing, which facilitates processing, adhesion of binders, minimizes self-adhesion of the fibers, or imparts specific properties (e.g., conductivity, etc.).

[0027] The individual fibers can be formed from a single material or multiple materials (e.g., from the materials listed below) or can themselves be composite materials. For example, an individual fiber can include a core (of a first material) coated with a second material such as a conductive material, an electrically insulating material, a thermally conductive material, or a thermally insulating material.

[0028] Regarding the composition, each individual fiber can be, for example, but not limited to, carbon, carbon nanotubes, glass, natural fibers, aramid, boron, metal, ceramic, polymer, synthetic fibers, and others. Non-limiting examples of metal fibers include steel, titanium, tungsten, aluminum, gold, silver, alloys of any of the foregoing, and shape memory alloys. "Ceramic" refers to all inorganic and non-metallic materials. Non-limiting examples of ceramic fibers include glass (e.g., S glass, E glass, AR glass, etc.), quartz, metal oxides (e.g., alumina), aluminum silicate, calcium silicate, rock wool, boron nitride, silicon carbide, and combinations of any of the foregoing. Non-limiting examples of suitable synthetic fibers include nylon (polyamide), polyester, polypropylene, meta-aramid, para-aramid, polyphenylene sulfide, and rayon (regenerated cellulose).

[0029] Any resin (thermoplastic or thermosetting) that binds to itself under heat and / or pressure can be used in combination with embodiments of the present invention.

[0030] Exemplary thermoplastic resins useful in connection with embodiments of the present invention include acrylonitrile butadiene styrene (ABS), ethylene tetrafluoroethylene (ETFE), fluorinated ethylene propylene (FEP), liquid crystal polymers (LCPs), polyamides (nylons), polyaryl ether ketones (PAEK), polybenzimidazoles (PBI), polybutylene terephthalate (PBT), polycarbonate (PC), and polycarbonate-ABS (PC-ABS), polyethylene (PE), polyether ether ketone (PEEK), polyetherimide (PEI), polyether sulfone (PES), polyethylene terephthalate (PET), perfluoroalkoxy copolymer (PFA), polyimide (PI), polymethyl methacrylate (PMMA), polyoxymethylene (polyacetal) (POM), polypropylene (PP), polyphosphoric acid (PPA), polyphenylene ether (PPE), polyphenylene oxide (PPO), polyphenylene sulfide (PPS), polyphenyl sulfone (PPSU), polystyrene (PS), polysulfone (PSU), polytetrafluoroethylene (PTFE), polyurethane (PU), polyvinyl chloride (PVC), styrene acrylonitrile (SAN), and styrene butadiene styrene (SBS), but are not limited thereto. The thermoplastic material can be a thermoplastic elastomer such as a polyurethane elastomer, a polyether ester block copolymer, a styrene block copolymer, a polyolefin elastomer, a polyether block amide, a thermoplastic olefin, an elastomer alloy (TPE and TPV), a thermoplastic polyurethane, a thermoplastic copolyester, a thermoplastic polyamide, and a thermoplastic silicone vulcanizate.

[0031] Non-limiting examples of suitable thermosetting resins include araldite, naphthalene, epoxy, melamine, phenol / formaldehyde, polyester, polyhexahydrotriazine, polyimide, polyisocyanate, polyurea, silicone, urea / formaldehyde, vinyl ester, phenol, and polycarbonate. Suitable thermosetting resins can be prepared as a partially cured B-stage.

[0032] For use in connection with the present invention, the preform is formed into a preform charge having a flat planar form factor.

[0033] FIG. 1 shows a method 100 according to the present teachings for fabricating two chiral parts having contoured surfaces, more specifically, a chiral part and its mirror image.

[0034] In accordance with operation S101, two identical instances of a preform charge from which two parts are formed are fabricated. According to an embodiment of the present invention, the preform charge has a flat planar shape and is fabricated from a single preform charge tool. As will be further described below in connection with FIG. 2, the preform charge having a particular arrangement of preforms is designed based on the requirements of the ultimately formed parts (e.g., mechanical and aesthetic specifications, external forces the parts will receive during use, etc.). Once the design of the preform charge is established, a preform charge tool for creating the preform charge is designed and fabricated.

[0035] In accordance with operation S102, the first part is fabricated from the first (identical) instance of the preform charge. This operation is described in more detail in connection with FIG. 4. In operation S103, the second part is fabricated from the second (identical) instance of the preform charge. This operation is described in more detail in connection with FIG. 5.

[0036] FIG. 2 shows a method for achieving operation S101, i.e., a method for fabricating two identical instances of a preform charge from which a chiral part and its mirror image are formed.

[0037] According to operation S201, chiral parts and their mirror images are designed. Usually, the design is based on (1) the overall physical attributes of the required parts, especially their size and shape, and (2) the mechanical specifications and the loads expected during use that the parts will receive. Consideration (2) provides the ideal fiber orientation of the molded part. The fiber orientation can be determined by the methods described in Patent Documents 3, 4, and 5, which are all incorporated herein by reference.

[0038] In operation S202, the part is projected onto a flat plane. For example, in the case of a foot bed, this includes projecting all rib-like structures and the perimeter of the foot bed onto a plane. The projected shape forms the basis for the preform charge (i.e., the placement of the preform) and the design of the fixture for the preform charge. The projection can be achieved, for example, using a CAD program. All CAD programs have a function to project an object onto a plane and create a sketch of the "shadow" of the object. This sketch is then used as the basis for the design of the preform charge and the cavity shape (or the layout of the crete) of the fixture for manufacturing the preform charge.

[0039] In operation S203, the gap that occurs when pressing a flat-plane preform charge onto a contoured surface (i.e., during the compression molding operation) is calculated.

[0040] For the above two operations, when an arc is projected onto a flat plane, the length of the projected image is shorter than the length of the arc (see operation S202). As a result, when a flat-plane layup of a preform sized based on the projection of the curved surface of the contoured part (i.e., the preform charge) is pressed against the surface of the contoured part (the mold), the layup is too short to completely cover the contoured surface, and a "gap" occurs (see operation S203).

[0041] Figures 3A and 3B show the gaps referred to in operation S203. Figure 3A shows a simplified mold 310 that includes a contoured surface 312 against which a flat planar preform charge 314 is pressed to imprint a contour on a finished part. Since both endpoints of the contoured surface 312 and the preform charge 314 extend the same horizontal distance, it will be understood that the length of the spline of the contoured surface 312 is longer than the length of the linear preform charge 314. Figure 3B shows the gaps 316A and 316B that occur when the preform charge 314 is pressed against the contoured surface 312 (a slight gap between the preform charge and the contoured surface is shown for clarity). The pressing operation is achieved by a plunger extending from the male portion of the mold 310 (not shown) or a properly shaped male feature. The gaps 316A and 316B are shown at the left and right ends of the contoured surface 312, but it will be understood that depending on the characteristics of the contour, the gaps may also appear at other locations.

[0042] In operation S204, based on the projection of the part obtained in operation S202, an arrangement of flat preforms is being fabricated. The ideal fiber arrangement determined in operation S201 is appropriately modified according to the constraints related to fabrication, as understood, for example, from Patent Document 3. Examples of constraints applicable to the preform include maximizing the number of straight (not bent) preforms (faster production), minimizing the number of inherent bend radii (reducing process variability), maximizing the length of the preform (higher strength for longer lengths), etc., but are not limited thereto.

[0043] To correct the gaps that occur when forming the contour on a flat planar preform charge during forming, a compensation preform (more than required based on the projection of the part) is added to the preform arrangement. This can be done by lengthening the preform near the gap or simply adding a preform to fill the gap. In some cases, short preforms (less than 40 mm) are added to the preform arrangement. Since the pressure is low in such (empty) regions, the fibers from such preforms will preferentially flow into the gap with the liquefied resin during forming. The gap can be calculated based on the following: - The absolute dimensions (length, width, height) of the gap; - The percentage of the adjacent section; - The volume; - The number of preforms with pre-determined dimensions that need to be added to fill the gap; - The number, length, or volume of short preforms (with "flowable" fibers) placed in the adjacent sections.

[0044] In operation S205, a fixture for the preform charge for forming the flat preform arrangement determined in operation S204 is fabricated. In some embodiments, the fixture for the preform charge includes a plurality of cleats / posts arranged to facilitate the fabrication of the preform arrangement. That is, by placing the preforms against the cleats, the desired preform arrangement is formed. Alternatively, a cavity with an appropriate size and shape is formed and the preforms are placed therein. Clamps are typically included in both types of fixtures.

[0045] In operation S206, the preforms are placed in the fixture for the preform charge. The clamps stabilize the preforms and apply a minimum pressure (typically less than 100 psig) thereto.

[0046] In operation S207, each preform is bonded. In the case of a preform containing a thermoplastic resin, this is achieved by heating the resin above its heat distortion temperature and below its melting temperature. The high temperature and the applied pressure bond the preforms to each other. As a result, a single mass of preforms is obtained, but the preforms retain their individuality and, importantly, their orientation with respect to each other. The array of preforms is then cooled and a preform charge is performed.

[0047] In operation S208, operations S206 and S207 are repeated to produce a second flat planar preform charge that is identical to the first preform charge.

[0048] Returning to FIG. 1, operation S102 shows forming a first part that exhibits chirality from a first instance of a flat planar preform charge. FIG. 4 shows the method of the preforming operation S102. In operation S401, a first flat planar preform charge is placed in a mold to produce a first part. The preform charge is placed in the mold in a first orientation. According to operation S402, the first part is produced by compression molding a first instance of the preform charge.

[0049] Continuing to refer to FIG. 1, in operation S103, a second part that is a mirror image of the first part is formed. FIG. 5 shows the method of the preforming operation S103. For each operation S501, a second instance of the flat planar preform charge is inverted or rotated 180° with respect to the first orientation about an axis parallel to what will be the "axis of reflection" of the first part - second part pairing (see, for example, FIG. 6B). According to operation S502, the second instance of the preform charge is placed in the mold in a second orientation. According to operation S503, the second part is produced by compression molding the second instance of the preform charge.

[0050] FIG. 6A is an example of a flat planar preform charge for fabricating a footbed made of a fiber composite material according to one embodiment of the present invention. The preform charge 620-1 consists of an array of preforms 622. In this example, all the preforms 622 are linear. The preforms are as long as possible and are consistent with the use of straight (i.e., non-bent) preforms. In the orientation shown in FIG. 6A, the preform charge 620-1 is placed in a mold to fabricate the "right side" footbed.

[0051] Referring now to FIG. 6B, another example of the same preform charge, "preform charge 620-2", is required to fabricate the left side footbed. According to the present teachings, the preform charge 620-2 is rotated 180 degrees about an axis "axis B-B" that is parallel to the "reflection axis" A-A. In this context, the reflection axis is the axis that "separates" the mirror-imaged preform charge. As shown, this rotation results in a second orientation for the preform charge, i.e., the "left" foot orientation.

[0052] Once this second direction (in this case the left foot) is established, the preform charge is placed in the mold for the left side footbed. Since the preform charge 620 has a flat planar shape, according to the present teachings, it can be flipped as shown to create the two orientations required for the right and left foot molds.

[0053] Note that in some embodiments, an improved compression molding process is used to compression mold the preform charge (operations S102 and S103). When a flat planar preform charge is pressed against the contoured surface of the mold (e.g., via a plunger or the like), a relatively rigid preform may snap under the applied force. In some embodiments, the male mold part (e.g., a plunger or the like) is brought into contact with the preform and only a minimal force is applied thereto. Next, the mold is heated to an intermediate temperature, e.g., just above the glass transition temperature Tg of the resin in the preform charge. As the resin in the preform charge softens, the plunger applies an increased force to the preform charge, conforming the preform charge to the contoured surface of the mold cavity. Finally, the temperature is raised to the melt temperature Tm of the resin to bring it into a molten flow state, and the pressure is increased (about 1000 - 5000 psi) to consolidate the resin and fibers during preform charging. After holding at pressure and temperature for a short time (up to a few minutes), the mold is cooled and depressurized.

[0054] FIG. 7 shows a fiber composite foot bed 730-1 having the illustrated contour, fabricated from a flat planar preform charge 620-1. Due to the planar shape of the preform charge, only a single preform charge design is required to fabricate both (chiral) parts.

[0055] Region 732 is "out-of-plane" with respect to the major surface of the fiber composite foot bed 730-1. This region is formed by extending the preform in this region of the preform charge or by providing a preform that is sufficiently short (less than 40 mm) to ensure that fibers from there flow into that region during the molding operation.

[0056] This disclosure describes several embodiments, and it should be understood that after reading this disclosure, many variations of the present invention can be readily devised by those skilled in the art, and the scope of the present invention is determined by the following claims.

Claims

1. A method for manufacturing a first part and a second part, wherein the first part and the second part are in a mirror image relationship with each other, exhibit chirality, and cannot be superimposed, and the method comprises: producing a first instance of a flat planar preform charge via a preform charge jig; placing the first instance of the preform charge in a first mold for use in forming the contoured first part, wherein the first instance of the preform charge has a first orientation within the first mold; compression molding the first part; producing a second instance of the preform charge via the preform charge jig, wherein the second instance is identical to the first instance; placing the second instance of the preform charge in a second mold for use in forming the second part, wherein the second instance of the preform charge has a second orientation within the second mold, and the second orientation is obtained by rotating the second instance of the preform charge 180 degrees with respect to the first orientation about an axis parallel to the axis of reflection of the first and second instances of the preform charge; compression molding the second part; A method comprising.

2. The method according to claim 1, comprising designing the flat planar preform charge, wherein the flat planar preform charge has a shape based on a planar projection of the first part.

3. The method according to claim 1, wherein the step of designing the flat planar preform charge comprises: placing a plurality of first fiber bundle-based preforms in appropriate regions of the planar protrusions; When pressing a flat preform charge onto the contoured surface of a first mold, calculating the size of a gap that would otherwise occur within the first mold; Complementing the first plurality of fiber bundle-based preforms by extending the lengths of some of the first plurality of preforms to fill the gap, or adding a second plurality of preforms to the flat planar preform charge; A method comprising: **Claim 4** The step of compression molding the first component includes pressing the first instance of the preform charge against the contoured surface of the first mold after the first instance of the preform charge has been heated to at least the heat distortion temperature of the resin in the first instance of the preform charge. The method according to claim 1. **Claim 5** The first component is a footbed for a right shoe, and the second component is a footbed for a left shoe. The method according to claim 1. **Claim 6** A method of manufacturing left and right footbeds for footwear, the left and right footbeds being in a mirror image relationship with each other but showing chirality and not being superimposable. The method includes: Manufacturing a first instance of a flat planar preform charge having a shape corresponding to a right foot via a preform charge jig; Placing the first instance of the preform charge in a first orientation within a first mold for forming a right footbed; Compression molding the first instance of the preform charge to form a right footbed; Manufacturing a second instance of the flat planar preform charge via the preform charge jig, the second instance having a shape corresponding to the right foot; Placing a second instance of the preform charge in a second mold for forming a left footbed in a second orientation, the second orientation being a mirror image of the first orientation; Compression molding the second instance of the preform charge to form a left footbed; A method comprising. **Claim 7** A method of manufacturing left and right footbeds for footwear, the left and right footbeds being in a mirror image relationship with each other, exhibiting chirality, and not being superimposable, the method comprising: Producing a first instance of a flat planar preform charge having a shape corresponding to a left foot via a preform charge jig; Placing the first instance of the preform charge in a first orientation in a first mold for forming a left footbed; Compression molding the first instance of the preform charge to form a left footbed; Producing a second instance of the flat planar preform charge via the preform charge jig, the second instance having a shape corresponding to the left foot; Placing the second instance of the preform charge in a second orientation in a second mold for forming a right footbed, the second orientation being a mirror image of the first orientation; Compression molding the second instance of the preform charge to form a right footbed; A method comprising.

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