Inflatable-based method for controlling formation of structural foam reinforcement

Abstract

A structural component of a vehicle includes a component having an inner surface defining a first hollow channel and a structural reinforcement contacting the inner surface of the component. The structural reinforcement and the component define a cross-section, and the structural reinforcement partially fills the cross-section. A method for forming a structural component includes inserting a bladder into a first hollow channel defined by an inner surface of a component and inflating the bladder in the first hollow channel, forming a cavity between the bladder and the inner surface, filling the cavity with a polymer resin, and foaming the polymer resin. A system for forming a structural component of a vehicle includes a component including a first hollow channel defined by an inner surface of the component, a bladder insertable into the first hollow channel of the component, and a supply line connected to an interior of the bladder.

Description

Technical Field

[0001] Structural foam serves as a lightweight solution for reinforcing and strengthening vehicle structures. In various applications, structural foam is used internally in hollow structural components. It can be used to manage collision energy forces and address noise, vibration, and acoustic harshness (NVH). Furthermore, the use of foam helps reduce vehicle weight, thereby improving fuel efficiency. Background Technology

[0002] Structural foam is foamed in place and can be formed using low-pressure injection molding. In low-pressure injection molding, foam is introduced into the hollow channels of the structural component and allowed to rise freely in place. Gravity can be used to confine the rise. However, when using this method, the foam fills the entire cross-section of the hollow channel. Furthermore, if the finite cross-section of the structural component includes structural foam or if structural foam of different materials is used in different locations, it may be necessary to form each section in a separate step, or to form multiple sections comprising at least different materials. This typically requires multiple molding stations and molding cycles to fill a single component.

[0003] Therefore, while current methods for structural foam reinforcements have achieved their intended purpose, there is a need for new and improved systems and methods for forming structural foam reinforcements. Summary of the Invention

[0004] According to several aspects, this disclosure relates to a method of forming a structural component of a vehicle. The method includes inserting an airbag into a first hollow channel defined by an inner surface of the component and inflating the airbag in the first hollow channel. The method further includes forming a cavity between the airbag and the inner surface and filling the cavity with a polymer resin. The method further includes foaming the polymer resin to form a polymer resin foam. Additionally, the airbag is deflated and removed from the first hollow channel.

[0005] In the aforementioned respect, the polymer resin foam partially fills the first hollow channel.

[0006] In any of the above aspects, the method further includes positioning the airbag within the cavity using a guide wire connected to the airbag.

[0007] In any of the above aspects, the method further includes forming a seal between the airbag and the inner surface to form a cavity.

[0008] In any of the above aspects, the method further includes providing an airbag including a restricted portion, wherein when the airbag is inflated, the expansion of the restricted portion is less than that of the rest of the airbag.

[0009] In any of the above aspects, the method further includes providing an airbag comprising an inflatable portion, wherein the inflatable portion expands more than the rest of the airbag when the airbag is inflated.

[0010] In any of the above aspects, the method further includes adjusting the inflation pressure of the airbag and adjusting the shape of the airbag.

[0011] In any of the above aspects, the method further includes crosslinking the polymer resin in the cavity.

[0012] In any of the above aspects, the airbag includes a protrusion, and the method further includes positioning the airbag within a first hollow channel using the protrusion.

[0013] In any of the above aspects, the method further includes venting the cavity through an vent defined by the component while the polymer resin is foamed.

[0014] According to a further aspect, this disclosure relates to a system for forming a structural component of a vehicle. The system includes a component comprising a first hollow channel defined by an inner surface of the component. The system also includes an airbag insertable into the first hollow channel of the component, wherein the airbag is inflatable and, upon inflation, contacts the inner surface of the component and defines a cavity. The system further includes a supply line connected to the interior of the airbag, wherein fluid is supplied through the supply line to the interior of the airbag to inflate the airbag.

[0015] In the aforementioned respect, the system also includes a port defined in the component for introducing polymer resin foam into the cavity.

[0016] In any of the above aspects, the system includes an exhaust port defined in the component for venting the cavity.

[0017] In any of the above aspects, the system includes a guide wire connected to the airbag to position the airbag in the component.

[0018] In some aspects, the guide line also includes an attachment ring for securing the airbag in the component.

[0019] In any of the above aspects, the airbag includes a restricted portion.

[0020] In any of the above aspects, the airbag includes an inflatable portion.

[0021] In some respects, the inflatable portion forms a protrusion extending from the body of the airbag, wherein the protrusion positions the airbag in the proper position within the first hollow channel of the component.

[0022] According to other aspects, this disclosure relates to a structural component of a vehicle. The structural component includes a component having an inner surface defining a first hollow channel. The structural component also includes a structural reinforcement that contacts the inner surface of the component, wherein the structural reinforcement and the component define a cross-section, and the structural reinforcement partially fills the cross-section.

[0023] In the aforementioned respect, the structural reinforcement defines the second hollow channel. Attached Figure Description

[0024] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of this disclosure in any way.

[0025] Figure 1A A vehicle frame including several structural components in a vehicle is shown according to several embodiments of the present disclosure.

[0026] Figure 1B A structural component of a vehicle, including a structural reinforcement formed therein, is shown according to an embodiment of the present disclosure.

[0027] Figure 1C An embodiment according to this disclosure is shown. Figure 1B The cross-section of the structural component.

[0028] Figure 2 Methods for forming structural reinforcements included in structural components are illustrated according to several embodiments of the present disclosure.

[0029] Figure 3A A structural component including an airbag is shown according to one embodiment of the present disclosure.

[0030] Figure 3B Structural components including an inflatable airbag are shown according to one embodiment of the present disclosure.

[0031] Figure 3C The illustration shows the introduction of a structural reinforcement according to one embodiment of the present disclosure, introduced into a cavity defined by a structural component and an inflatable airbag.

[0032] Figure 3D A structural reinforcement and a deflated airbag formed in a structural component according to an embodiment of the present disclosure are shown.

[0033] Figure 3E A structural component according to one embodiment of the present disclosure is shown, the structural component including a plurality of structural reinforcements formed in the structural component after the deflated airbag has been removed.

[0034] Figure 4 An airbag according to one embodiment of the present disclosure is shown, the airbag including regions exhibiting anisotropic properties to form different airbag shapes.

[0035] Figure 5 A cross-section of a structural component according to an embodiment of the present disclosure is shown, the structural component including a structural reinforcement formed using an airbag exhibiting anisotropic properties.

[0036] Figure 6 It is a graph showing the effect of adding a structural reinforcement to a structural component according to an embodiment of the present disclosure.

[0037] Figure 7A The cross-section of a structural component in which no structural reinforcement is formed is shown.

[0038] Figure 7B The test results were shown. Figure 7A The cross-section of the structural component.

[0039] Figure 7C The test results were shown. Figure 7A A top view of the structural components.

[0040] Figure 8A A cross-section of a structural component including a structural reinforcement is shown according to an embodiment of the present disclosure.

[0041] Figure 8B The test results were shown. Figure 8A The cross-section of the structural component.

[0042] Figure 8C The test results were shown. Figure 8A A top view of the structural components.

[0043] Figure 9A A structural component including a structural reinforcement is shown according to an embodiment of the present disclosure.

[0044] Figure 9B The test results were shown. Figure 9A The cross-section of the structural component.

[0045] Figure 9C The test results were shown. Figure 9A A top view of the structural components. Detailed Implementation

[0046] The following description is merely exemplary in nature and is not intended to limit this disclosure, its application, or its uses. Furthermore, it is not intended to be bound by any express or implied theory set forth in the foregoing introduction, summary of the invention, or detailed description. It should be understood that throughout the drawings, corresponding reference numerals indicate similar or corresponding parts and features.

[0047] As used herein, the term "vehicle" is not limited to automobiles. While this technology is described primarily in connection with automobiles, it is not limited to automobiles. These concepts can be used in a wide variety of applications, such as those relating to motorcycles, mopeds, locomotives, aircraft, ships and other means of transportation, or other structural or non-structural applications that may require the deposition of polymer resin in channels formed in components.

[0048] This disclosure relates to structural components including structural reinforcements, an inflatable-based system for forming structural reinforcements within the structural component, and an inflatable-based method for controlling the molding of structural foam reinforcements. The structural component includes parts that perform at least one of the following functions: supporting vehicle weight, absorbing road impacts, and managing collision energy. Structural reinforcements are understood herein as materials that improve the mechanical properties of the structural component, such as the compressive strength, flexural strength, tensile strength, or energy absorption capacity of the structural component.

[0049] Figure 1A A vehicle 100 is shown, including a frame 102, which includes several structural components 103, such as A-pillar 104 and B-pillar 106. Figure 1B and Figure 1C B-pillar 106 is shown. Structural component 103 is formed by component 112 including a hollow channel. For example, B-pillar 106 is formed by component 112, which includes an inner surface 114 defining a first hollow channel 116 within component 112. The first hollow channel 116 is an elongated hollow channel. Structural reinforcements 120, 122, 124, 126 contact the inner surface 114 of component 112 and are discretely formed at different locations within the first hollow channel 116 of component 112. Furthermore, structural reinforcements 120, 122, 124, 126 are formed from polymer resin foam exhibiting a honeycomb structure. As shown, four structural reinforcements are provided. However, it should be understood that one or more structural reinforcements may be provided for a single structural component 103, for example, between one and ten structural reinforcements. Additionally, where multiple structural reinforcements may be present, the structural reinforcements may be made of a variety of materials with different compositions, physical properties, and mechanical properties.

[0050] Structural reinforcements 120, 122, 124, and 126 only partially fill a given cross-section of the first hollow channel 116 of component 112, without filling the entire cross-section of the first hollow channel 116. For example... Figure 1CAs shown, structural reinforcement 122 fills a portion of the cross-section of the first hollow channel 116, and structural reinforcement 122 is hollow, defining a second hollow channel 130. In other aspects, structural reinforcement 122 fills a portion of the cross-section of the first hollow channel 116, and the second hollow channel 130 is defined by both structural reinforcement 122 and component 112. In some aspects, structural reinforcement 122 blocks a given cross-section of the first hollow channel 116 in the range of 5% to 90% (inclusive). Partially filling component 112 with structural reinforcement 112 reduces the weight of structural component 103 compared to completely filling structural component 103 with structural reinforcement 112, thus contributing to a reduction in the overall weight of the vehicle 100.

[0051] Figure 2 A method 200 for forming structural reinforcements 120, 122, 124, and 126 within structural component 103 is shown, with reference to Figures 3A to 3E , Figures 3A to 3E A system for forming a structural component 103 of a vehicle is shown. The method 200 begins at block 202 by inserting an uninflated insertable airbag into a first hollow channel 303 defined by the inner surface 305 of a component 304 of the structural component 300. The uninflated airbag 302 includes guide lines 306, 308 connected to and extending from either side of the airbag 302 to aid in positioning the airbag 302 within the component 304. The guide lines 306, 308 also include attachment rings 310, 312 for securing the airbag 302 in place to prevent movement of the airbag 302 within the component 304 during molding. The attachment rings 310, 312 may be connected to the structural component 300 or to a fixing device that holds the structural component 300 in place during molding. In some aspects, the airbag 302 is formed of silicone, polypropylene, polyamide-reinforced polypropylene, or rubber. In addition, the airbag 302 is coated with a release compound or otherwise treated to prevent or at least reduce adhesion to the polymer resin foam.

[0052] The airbag 302 also includes confined portions 314, 316, and 318, which exhibit less expansion than the rest of the airbag 302 when it inflates. The confined portions 314, 316, and 318 can be formed by winding wire, metal wire, tape, or elastic band around the airbag 302, or by forming the confined portions 314, 316, and 318 of the airbag 302 with one or more different materials, which exhibit different degrees of ductility or deformation when force is applied to the airbag 302 by the fluid 320 that inflates it. Additionally, local constraints such as seams, ties, and other stitching can also affect the shape of the inflated airbag 302 and provide confined portions that constrain the expansion of the airbag 302. Different geometries of the airbag 302 and structural reinforcements 120, 122, 124, and 126 can be formed by varying the amount or position of the winding or by using different materials. Therefore, although three restricted sections are shown, any number of restricted sections can be provided, such as one to ten. Furthermore, it should be understood that although the restricted sections are shown as extending around the entire periphery of the airbag 302, the restricted sections may be limited to a few segments around the periphery of the airbag.

[0053] In addition to the restricted portion, an expandable portion can also be provided, and references can be made. Figure 4 The diagram illustrates an airbag 302 including confined portions 314, 316 and an inflatable portion 328. As described above, the confined portions 314, 316, 318 limit the degree to which the airbag 302 can inflate within a given area relative to the rest of the airbag 302. When the airbag inflates, the inflatable portion 328 expands to a greater extent relative to the rest of the airbag 302. When the airbag 302 is filled with fluid, the inflatable portion 328 exhibits different deformation characteristics than the rest of the airbag 302, namely greater deformation and greater ductility. These inflatable portions 328 of the airbag 302 are formed by varying the material or thickness of the wall portions. When inflated, portions 328 generate... Figure 5 The protrusion 327 extends from the main body 329 of the airbag 302 shown. Figure 5 A cross-section of an inflatable airbag 302 within component 304 is shown. In the illustrated aspect, protrusions 327 position the airbag 302 within a first hollow channel 303 and hold it in place within the first hollow channel 303 of component 304. When the airbag 302 inflates, the combination of the confined portions 314, 316, 318 and the inflatable portion 328 can be arranged and adjusted to form any number of geometries. Therefore, although four protrusions 327 are shown, any number of protrusions 327 can be provided.

[0054] In box 204, refer to Figure 3BThe airbag 302 is inflated to a given pressure by filling it with fluid 320 (e.g., air, inert gas, or liquid) via a supply line 322 connected to the interior 323 of the airbag 302. The airbag 302 contacts and impacts the inner surface 324 of the component 304, forming a seal with the inner surface 324 to define a plurality of cavities 330, 334, 336 between the inner surface 305 of the component 304 and the airbag 302. It should be understood that although a plurality of cavities are shown, one cavity or two or more cavities may be defined. In some aspects, the temperature of the fluid 320 may be adjusted, for example by circulating the fluid through a cooler or heater, to facilitate the molding of the structural reinforcement by aiding in the curing or cooling of the resin subsequently introduced into the cavities 330, 332, 334. In some aspects, the inflation pressure in the airbag 302 is adjusted to adjust the shape of the airbag 302. Adjustments may occur when cavities 330, 332, and 334 are filled with polymer resin, or when polymer resin foam 348 is foamed.

[0055] After the air bladder 302 is filled in box 204, cavities 330, 332, and 334 are filled in box 208 with polymeric resin that forms polymeric resin foam 348, resulting in structural reinforcements 342, 344, and 346. In some aspects, the polymeric resin releases gas through a chemical reaction to form polymeric resin foam 348, or the polymeric resin includes a foaming agent or expandable particles within the polymeric resin. In some aspects, foaming can be triggered when the polymeric resin is heated. Examples of polymeric resin foam 348 include, for example, one-component or two-component foams, thermoplastic materials including expandable particles or foaming agents, or thermoplastic materials mixed with gas after melting and before molding. The polymeric resin used to form the polymeric resin foam 348 includes, for example, one or more of the following: polyurethane, epoxy resin, polyisocyanurate, ethylene vinyl acetate, polyolefin, polyolefin-ethylene vinyl acetate blend, polybutylene terephthalate, polycarbonate, polyphenylene ether, polyethylene terephthalate, and acrylonitrile butadiene styrene. As described above, when a given structural component 300 includes multiple structural reinforcements 342, 344, 346, more than one type of polymeric resin foam 348 can be used. Different polymeric resins can be used to form the polymeric resin foam 348 of each structural reinforcement, or the same polymeric resin with different amounts of blowing agent can be used. Different polymeric resin foams 348 can exhibit different densities or different mechanical properties, including compressive strength and tensile strength. In an additional or alternative aspect, different amounts of polymeric resin can be injected into a given cavity to provide polymeric resin foams of different densities.

[0056] The polymer resin forming the polymer resin foam 348 is introduced by a runner system 352. In some aspects, the runner system 352 is formed in one or more fixtures 354, by which the component 304 is held. In other aspects, the runner system 352 is formed by a tube connectable to the component 304. The component 304 defines a plurality of ports 356, 358, 360, which are connected to cavities 330, 332, 334 and connectable to the runner system 352 to introduce the polymer resin of the polymer resin foam 348 into the cavities 330, 332, 334 before or after foaming. Furthermore, the runner system 352 is connected to a polymer resin supply system 362. In some aspects, the polymer resin supply system 362 includes one or more of the following: a supply tank, a reservoir, a metering pump, a feeder, an extruder, and a mixer. In some respects, each port 356, 358, 360 is connected to its own flow channel system 352, which in turn is connected to its own polymer resin supply system 362, and each polymer resin supply system 362 is individually metered so that different amounts of precursor are injected into each location. This allows control over the density of the polymer resin foam 348 in each cavity 330, 332, 334. Furthermore, vents 366, 368, 370 are defined in component 304 and connected to cavities 330, 332, 334 to expel air from cavities 330, 332, 334 when polymer resin of the polymer resin foam 348 is injected into the cavities 330, 332, 334.

[0057] Alternatively, prior to filling cavities 330, 332, and 334 in box 208, in box 206, the polymer resin is melted, its various components are mixed, or the resin is bonded to a gas. For example, when using a thermoplastic resin, the polymer resin is melted by heating and, in some respects, bonded to a gas. In another example, when using a two-component resin, such as polyurethane or epoxy, the resin components are mixed. Alternatively, as an alternative, the polymer resin is introduced without pretreatment (such as melting, mixing, or bonding to a gas), as in the case of a one-component polyurethane.

[0058] After the cavities 330, 332, and 334 of the polymer resin in box 208 are filled with the polymer resin foam 348, the polymer resin crosslinks or cures within the cavities 330, 332, and 334. For example, in the case where the polymer resin is a two-component mixture, the polymer resin can form crosslinks and cure into polymer resin foam 348. In other instances, heating the polymer resin to initiate crosslinking, removing the foaming agent from the molten polymer resin, or expanding the expandable particles in the molten polymer resin can cause gas release or expansion, forming polymer resin foam 348. When the polymer resin of polymer resin foam 348 is provided as a melt, the foamed polymer resin can be cooled and cured. It should be understood that the polymer resin does not need to be fully crosslinked or fully cooled to ambient temperature, but only needs to be sufficiently crosslinked or sufficiently cooled so that the structural reinforcements 342, 344, and 346 can resist deformation when the airbag 302 is removed.

[0059] refer to Figure 3D and Figure 3E In box 210, once the polymer resin foam 348 has fully cured, in box 212, the airbag 302 is deflated, and in box 214, the airbag is removed from the structural reinforcements 342, 344, and 346. In some aspects, the airbag 302 can be deflated simply by pumping liquid out of the airbag 302 or by reducing the pressure of the fluid 3208 applied to the airbag 302 through the elastic recovery of the airbag 302 or an external source. The structural component 300 is formed by component 304 and structural reinforcements 342, 344, and 346. As shown, the structural reinforcements 120, 122, 124, 126, 342, 344, and 346 are in various shapes depending on the shape of component 112, 304, and airbag 302.

[0060] The inclusion of structural reinforcements 120, 122, 124, 126, 342, 344, and 346 in structural component 300 improves mechanical properties. Figures 6 to 9C Illustrative examples are provided, which are exemplary in nature and are not intended to limit the scope of this disclosure. Figure 6 The diagram includes a comparison graph showing the effect of hollow structural component 700 with structural components 800 and 900 including structural reinforcements 804 and 904. Structural components 700, 800, and 900 are elongated tubes formed using an FDM 3D printer with polyetherimide (ULTEM9085, available from SABIC in Houston, Texas) and a wall thickness of 1 mm. Within structural component 800, there is a material with a density of 3 lb / ft... 3 A structural reinforcement made of polyurethane foam with a density of 10 lb / ft (lbs / ft) extends along the length of structural member 800 and has a foam thickness of 10 mm.3 A structural reinforcement formed of polyurethane foam, which extends along the length of structural member 900 and has a thickness of 10 mm. Figure 7A , Figure 8A and Figure 9A The roundness of structural components 700, 800, and 900 is shown before testing.

[0061] Forces were applied to structural members 700, 800, and 900 using an Instron three-point bending frame. The structural members were fixed to two roller supports and indented by a 30 kN load cell, which measured the deflection of the top surface. An extensometer was placed below the members to measure the deflection at the bottom. Forces were applied at a rate of 3 mm per minute. As shown in the graphs, the amount of force causing deformation of structural member 700 (without structural reinforcements) (plotted as line 710) was lower than the amount of force causing deformation of structural members 800 and 900 (including structural reinforcements 804 and 904) (plotted as lines 810 and 910). Figure 7B , Figure 8B and Figure 9B The diagram shows the shrinkage and loss of roundness of structural components 700, 800, and 900 upon failure. (See figure.) Figure 7C , Figure 8C and Figure 9C A top view is shown of the combined deformations 712, 812, and 912 of structural components 700, 800, and 900 upon failure.

[0062] While the methods described herein pertain to automotive structural components, it should be understood that these methods can be used to integrate structural reinforcements into other structural components that include or define hollow passages. Structural components include those that perform at least one of the following functions: supporting vehicle weight, absorbing road impacts, and managing collision energy. Structural components include, for example, various pillars (A, B, C, D) as described above, radiator core supports, front and rear bumper reinforcements, crossbeams, seat frames, front and rear door anti-collision beams, etc. Furthermore, it should be understood that the methods used herein can be used to deposit other materials, such as sound insulation materials within air ducts, into hollow passages defined by other vehicle components.

[0063] Structural components including structural reinforcements and methods for forming such components offer several advantages. Compared to molding methods that require the structural reinforcements to be freely raised and fully filled within the structural component, advantages include, for example, the ability to form multiple structural reinforcements in a single step within the structural component. This results in a reduction in the cycle time for structural components including more structural reinforcements (requiring multiple filling stations). Other advantages include weight reduction due to the ability to partially fill the structural reinforcements within the structural component. This leads to a lighter structural component, contributing to a lighter vehicle.

[0064] The descriptions in this disclosure are merely exemplary in nature, and variations thereof without departing from the spirit and scope of this disclosure are intended to be within its scope. Such variations should not be considered as departing from the spirit and scope of this disclosure.

Claims

1. A method for forming a structural component of a vehicle, comprising: The airbag is inserted into the first hollow channel defined by the inner surface of the component; Inflate the airbag in the first hollow channel; Multiple cavities are formed between the airbag and the inner surface; The plurality of cavities are filled with polymer resin; The polymer resin is foamed to form a plurality of polymer resin foam structure reinforcements that are in contact with the inner surface; Deflate the airbag; as well as Remove the airbag from the first hollow channel; The plurality of polymer resin foam structure reinforcements partially fill the first hollow channel and define a second hollow channel, the second hollow channel being defined by both the plurality of polymer resin foam structure reinforcements and the inner surface of the component; The airbag includes a confined portion and an inflatable portion. When the airbag is inflated, the expansion amount of the confined portion is less than that of the rest of the airbag, and the expansion amount of the inflatable portion is greater than that of the rest of the airbag. Specifically, filling the plurality of cavities with polymer resin includes: using a plurality of polymer resin supply systems to supply polymer resin to the plurality of cavities respectively. The plurality of polymer resin supply systems are respectively connected to the plurality of cavities and are configured to independently meter to supply different amounts of polymer resin to different cavities, thereby controlling the density of polymer resin foam in each cavity.

2. The method according to claim 1, further comprising: The airbag is positioned within the first hollow channel using a guide wire connected to it.

3. The method according to claim 1, further comprising: A seal is formed between the airbag and the inner surface to form the plurality of cavities.

4. The method according to claim 1, wherein, The airbag includes a protrusion, and the method further includes positioning the airbag within the first hollow channel using the protrusion.

5. The method according to claim 1, further comprising: While the polymer resin is foamed, the plurality of cavities are vented through the vents defined by the component.

6. A system for forming structural components of a vehicle, comprising: A component, including a first hollow channel defined by the inner surface of the component; An airbag, which can be inserted into a first hollow channel of the component, wherein the airbag is inflatable and, when inflated, contacts the inner surface of the component and defines a plurality of cavities for receiving material to form a plurality of structural reinforcements; and A supply line is connected to the interior of the airbag, through which fluid is supplied to the interior of the airbag to inflate the airbag; The airbag is configured to deflate and be removed from the first hollow channel after the plurality of structural reinforcements are formed. The plurality of structural reinforcements partially fill the cross-section of the first hollow channel and define a second hollow channel, which is defined by both the plurality of structural reinforcements and the inner surface of the component. The airbag includes a confined portion and an inflatable portion. When the airbag is inflated, the expansion amount of the confined portion is less than that of the rest of the airbag, and the expansion amount of the inflatable portion is greater than that of the rest of the airbag. The system further includes multiple polymer resin supply systems, which are respectively connected to the multiple cavities and configured to independently meter to provide different amounts of polymer resin to different cavities.

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