Heated polymer sheet material supply process

Abstract

A process for forming a rigid thermoplastic polymer sheet material, the process including heating a rigid thermoplastic polymer sheet to a forming temperature in a heating zone under a heating vacuum range to form a heated rigid thermoplastic polymer sheet material, the process further including conveying the heated rigid thermoplastic polymer sheet material from the heating zone under a feed vacuum range to feed the heated rigid thermoplastic polymer sheet material to a forming zone under the feed vacuum range, the process also including forming the heated rigid thermoplastic polymer sheet material into a molded article in the forming zone.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Application No. 17 / 667,211, filed February 8, 2022, the disclosure of which is incorporated herein by reference in its entirety.

[0002] The present disclosure relates to a heated polymeric sheet material application process. [Background technology]

[0003] The polymeric material can be formed into a molded article. The polymeric material can be formed of a thermoplastic or thermoset material. The polymeric material can be a polymer matrix composite material that includes reinforcing fibers. Non-limiting examples of articles that can be formed from the polymeric material include cosmetic products, automotive exterior parts (e.g., hoods, fenders, decklids, roofs, bumpers, fascias), automotive structural parts (e.g., seats, bumper beams, skid plates, cargo beds, pickup truck cargo boxes, bed liners), automotive interior parts (e.g., cosmetic panels), building products, consumer products (e.g., sporting goods and appliances), medical products and parts, and the like. Summary of the Invention

[0004] In one embodiment, a process for forming a polymer sheet material is disclosed. The process includes heating a first polymer sheet to a first forming temperature in a first heating zone under a heating vacuum range to form a first heated polymer sheet material. The process also includes transferring the first heated polymer sheet material from the first heating zone under a supply vacuum range to provide the first heated polymer sheet material to a forming zone under the supply vacuum range. The process also includes forming the first heated polymer sheet material into a first molded article in the forming zone. The process also includes heating a second polymer sheet to a second forming temperature in a second heating zone under a heating vacuum range to form a second heated polymer sheet material, where the first and second heating zones are different. The process also includes transferring a second heated polymer sheet material from the second heating zone under a supply vacuum range after the first molded article exits the forming zone to provide the second heated polymer sheet material to a forming zone under the supply vacuum range. The process also includes forming the second heated polymeric sheet material into a second article in a forming zone.

[0005] In another embodiment, a process for forming a rigid thermoplastic polymer sheet material is disclosed. The process includes heating a rigid thermoplastic polymer sheet to a forming temperature in a heating zone under a heating vacuum range to form a heated rigid thermoplastic polymer sheet material. The process further includes conveying the heated rigid thermoplastic polymer sheet material from the heating zone under a feed vacuum range to feed the heated rigid thermoplastic polymer sheet material to a forming zone under the feed vacuum range. The process also includes forming the heated rigid thermoplastic polymer sheet material into a molded article in the forming zone.

[0006] In yet another embodiment, a process for forming a heated polymer sheet material is disclosed. The process includes heating a polymer sheet to a forming temperature in a heating zone in a single chamber including a forming zone under a vacuum range to form a heated polymer sheet material. The process also includes transporting the heated polymer sheet material from the heating zone under a vacuum range to provide the heated polymer sheet material to a forming zone under a vacuum range. The process also includes forming the heated polymer sheet material in the forming zone into a molded article. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a cutaway perspective view of a first system configured to implement a heated polymeric sheet material dispensing process according to a first embodiment. [Diagram 2] 2 is a cross-sectional view, a side view, and a partial cross-sectional view of the first system shown in FIG. 1 taken along line 2-2 of FIG. [Diagram 3] FIG. 3 is a perspective view of a second system configured to implement a heated polymeric sheet material dispensing process according to a second embodiment. [Figure 4] 4 is a cross-sectional view, a side view, and a partial cross-sectional view of the second system shown in FIG. 3 taken along line 4-4 of FIG. [Diagram 5] FIG. 5 is a cutaway side view of a third system configured to implement a heated polymer sheet material dispensing process according to a third embodiment. [Figure 6] 6 is a cross-sectional view, a side view, and a partial cross-sectional view of the third system shown in FIG. 5 taken along line 6-6 of FIG. [Figure 7] FIG. 7 is a cross-sectional, side and partial cross-sectional view of a fourth system configured to implement a heated polymer sheet material dispensing process according to a fourth embodiment. [Figure 8] FIG. 8 illustrates a cross-sectional view, a side view, and a partial cross-sectional view of a system according to a fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Where necessary, detailed embodiments of the present invention are disclosed herein, but it should be understood that the disclosed embodiments are merely exemplary of the present invention, which may be embodied in various alternative forms. The figures are not necessarily to scale, and some features may be exaggerated or minimized to show details of specific components. Therefore, specific structural and functional details disclosed herein are not to be construed as limiting, but merely as a representative basis for teaching those skilled in the art to employ the present invention in various ways.

[0009] The embodiments of the present disclosure are described below. However, it should be understood that the disclosed embodiments are merely exemplary, and other embodiments may take various alternative forms. The figures are not necessarily to scale, and some features may be exaggerated or minimized to show the details of certain components. Therefore, the specific structural and functional details disclosed herein should not be interpreted as limiting, but merely as a representative basis for teaching those skilled in the art to adopt the embodiments in various ways. As will be understood by those skilled in the art, various features illustrated and described with reference to any figure can be combined with features shown in one or more other figures to create an embodiment not explicitly illustrated or described. The combination of the illustrated features provides a representative embodiment for a typical application. However, various combinations and modifications of features consistent with the teachings of the present disclosure may be desired for a particular application or implementation.

[0010] The term "about" may be used herein to describe disclosed or claimed embodiments. The term "about" may modify a value disclosed or claimed in this disclosure. In such cases, "about" may mean that the modifying value is within ±0%, 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, or 10% of the modified value.

[0011] The polymeric material can be formed into a molded article. The polymeric material can be formed of a thermoplastic or thermoset material. The polymeric material can be a polymer matrix composite material that includes reinforcing fibers. Non-limiting examples of articles that can be formed from the polymeric material include trim, automotive exterior parts (e.g., hoods, fenders, decklids, roofs, bumpers, fascias), automotive structural parts (e.g., seats, bumper beams, skid plates, cargo beds, pickup truck cargo boxes, bed liners), automotive interior parts (e.g., cosmetic panels), building products, consumer products (e.g., sporting goods and appliances), medical products and parts, and the like.

[0012] The polymeric material may be molded into a polymeric sheet material before being molded into a molded article. The polymeric sheet material may be heated before being subjected to the molding process. As non-limiting examples, the molding process may be a compression molding process, a thermoforming process, or a closed mold process. Non-limiting examples of thermoforming processes include vacuum molding processes, pressure molding processes, plug-assist molding processes, matched-die molding processes, etc. Examples of closed mold processes include injection molding processes, compression molding processes, resin transfer molding (RTM) processes, etc.

[0013] Existing processes for forming polymer sheet materials into molded articles have several problems. As discussed above, the polymer sheet material may be heated prior to the forming process. Heating certain polymer sheet materials to the appropriate forming temperature may cause the polymer sheet material to degrade, such as oxidize, depending on the environmental conditions. The heated polymer sheet material may be transferred from an oven to a mold under ambient conditions, including air. Prolonged exposure to such environmental conditions and air may cause the surface temperature of the heated polymer sheet material to drop significantly, which may result in molding and / or cosmetic defects. The polymer sheet material may be a semi-crystalline thermoplastic polymer sheet material. The surface of this type of polymer sheet material may crystallize during transfer of the polymer sheet material, which may result in molding and / or cosmetic defects. The polymer sheet material may be a water-absorbent polymer sheet material. This type of polymer sheet material may cause hydrolytic degradation and the development of air bubbles within the polymer sheet material if insufficiently dried prior to or during the heating process. Another drawback of current proposals is that forming polymer sheet materials using matched die sets or other pressure-based forming processes may entrap air, which may result in molding and / or cosmetic defects.

[0014] In view of the above, there is a need for a heated polymer sheet material delivery process that overcomes one or more of the above-identified shortcomings of existing processes. Meeting such a need may expand the use of polymer sheet materials to form molded articles. In one or more embodiments, a heated polymer sheet material delivery process is disclosed that transfers heated polymer sheet material from a heating chamber under a delivery vacuum range to deliver the heated polymer sheet material into a mold cavity. This process may reduce and / or eliminate one or more shortcomings associated with conventional processes, such as processes that transfer and deliver heated polymer sheet material under ambient conditions, including air.

[0015] In one or more embodiments, a process for providing a heated polymer sheet material is disclosed. The heated polymer sheet material providing process may include heating a polymer sheet material to a forming temperature in a heating chamber to form a heated polymer sheet material. The heating chamber may be an insulated or non-insulated heating chamber. The heating chamber may use convection heat, conductive heat (e.g., conductive heat generated from an isobaric double belt press), electromagnetic heat, and / or radiant heat (e.g., infrared radiation heat). When using convection heat, the heating chamber may circulate a gas (e.g., air in an ambient atmosphere or one or more inert gases in an inert atmosphere) in the heating chamber to form a heated atmosphere. An inert gas may be a gas that does not chemically interact or react with the polymer sheet material in the forming temperature range. Non-limiting examples include nitrogen, helium, argon, and combinations thereof. The heating chamber may be an oven.

[0016] The heated polymer sheet material feeding process may further include transferring the heated polymer sheet material from the heating chamber under a feeding vacuum range to feed the heated polymer sheet material to the forming chamber. The feeding vacuum range may be from 0 torr to 760 torr. The feeding vacuum range may be from 10 -12 The supply vacuum range is 10 -9 torr~10 -12 The supply vacuum range can be as high as 10 -3 torr~10 -9 The supply vacuum range is from 25 torr to 10 -3 The supply vacuum range can be a medium vacuum of 760 torr to 25 torr. The supply vacuum range can have a residual atmosphere. The residual atmosphere can be an ambient atmosphere or an inert atmosphere. The residual atmosphere can be intentionally reactive. The disclosed supply vacuum ranges and conditions can also be used for heating vacuum ranges and conditions.

[0017] The heated polymeric sheet material supply process may further include forming the heated polymeric sheet material into a molded article in a molding chamber. This forming step may be performed using a compression molding process, a thermoforming process, or a closed mold process. Non-limiting examples of thermoforming processes include vacuum forming, pressure forming, plug assist molding, matched die molding, etc. Non-limiting examples of closed mold processes include injection molding, compression molding, resin transfer molding (RTM) processes, etc.

[0018] In one or more embodiments, the polymeric sheet material is a sheet formed of a polymeric material. In one or more embodiments, the sheet has first and second surfaces extending generally planarly in the x- and y-directions and forming a generally uniform thickness therebetween. The generally uniform thickness may vary based on the generally planar first and second surfaces. The "generally uniform thickness" may be any of the following thicknesses, or within any two ranges of thickness: 0.25, 0.5, 0.75, 1, 1.5, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 25.4, 30, 35, 40, 45, 50, 50.4 mm. Non-limiting examples of polymer sheet materials and formats include tape-based laminate sheets from 0.25 mm to 25 mm ± 10%, organic sheets from 0.25 mm to 25 mm ± 10%, glass mat thermoplastic (GMT) sheets from 0.25 mm to 25 mm, extrusions of molding compounds such as LFT-D having generally constant but widely varying cross-sections, and combinations thereof that may be combined to have a constant or varying range of thicknesses or profiles (e.g., rectangular, circular, irregular). In other embodiments, the thickness of the polymer sheet material may vary along the x and / or y directions of the polymer material, for example, when multiple formats are combined.

[0019] In one or more embodiments, the polymer sheet material may be a polymer thermoset sheet material or a polymer thermoplastic sheet material. Based on the type of resin used in the polymer sheet material, the polymer sheet material may be classified as thermoset or thermoplastic. Thermoset resins are composed of monomers, prepolymers, or other polymeric materials that undergo a chemical reaction to produce long polymer chains, which are then polymerized to harden into a plastic material that cannot be remelted. This chemical reaction may be accelerated by heat and / or one or more catalysts. A prepreg material is an intermediate product that combines reinforcing fibers and a thermoset resin. A thermoset sheet may include one or more layers of the same or different prepreg materials. Such a thermoset sheet may be moldable at room temperature. Alternatively, a thermoset sheet may be too rigid to mold at room temperature and require the application of heat prior to polymerization to soften the thermoset resin and promote acceptable molding behavior.

[0020] The thermoplastic resin may include a thermoplastic resin used to form a rigid thermoplastic sheet material. The rigid thermoplastic sheet material can be softened when heated to form a molded article in various processes, but remains relatively rigid at the temperature of use. The thermoplastic resin may include a thermoplastic elastomer used to form the thermoplastic sheet material. The thermoplastic elastomer can be molded at high temperatures, but remains flexible at the temperature of use (e.g., ambient temperature). The rigid thermoplastic sheet material can be molded in the softened state, and then hardened when cooled to set the shape of the molded article. This cycle can be repeated, possibly indefinitely. The thermoplastic resin can be used in a pure form, referred to as a neat form. Alternatively, the thermoplastic resin may be combined (e.g., compounded) with one or more fillers, one or more additives, and / or one or more other thermoplastic resins to form a blend or alloy. Reinforcing materials (such as reinforcing fibers) may be added to the thermoplastic resin to create a composite material. These improvements can improve the cost, processability, and functionality of the resulting thermoplastic resin material.

[0021] Polymer thermoplastic materials can be used in a variety of forms. For relatively short lengths of reinforcing fibers (e.g., less than 1 or 2 mm in length), pellets or granules can be used because of the processing flexibility due to flowability. Many pellet-based processes start with an extruder where the pellets are fed and heated. The molten compound is then fed under pressure in a profile extrusion or injection molding process to a die where the compound is cooled and set into the desired shape.

[0022] In one or more embodiments, polymer thermoplastic materials may also be used in sheet format. The sheet format may have one or more advantages over the pellet format. The sheet may include multiple thin layers. Each layer may be individually tailored to a set of criteria into a pre-integrated composite structure. The sheet format may also be configured to form large, thin parts at lower cost and with better dimensional control. With knit lines where multiple flow fronts come together, the use of sheet formats may avoid the use of injection molding processes. The use of sheet formats with such knit lines may often strengthen parts when composite materials are used, as reinforcements bridge the knit lines.

[0023] In one or more embodiments, compression molding is a process in which a heated sheet of one or more polymeric thermoplastic materials is transferred from a heated chamber into an open matched die set, which is then closed under pressure to conform the polymeric thermoplastic sheet material to both sides of the die. In one or more embodiments, the sheet of material fits around the circumference of a die, and pressure from the die causes the thermoplastic sheet material to flow and fill the intended shape. The thermoplastic material is then cooled in the die, setting the shape, and then demolded. Compression molding may also be utilized with thermosetting materials, where the thermosetting sheet material enters a heated die, typically at or below the die temperature, and heat from the die initiates a chemical reaction that polymerizes the resin.

[0024] In one or more embodiments, thermoforming may be used to shape the polymeric thermoplastic sheet material. In one embodiment, the thermoplastic sheet is held in a tensioning device (e.g., a tension frame, clamps, or transfer frame) configured to clamp the periphery of the polymeric thermoplastic sheet material. Within the tensioning device, the polymeric thermoplastic sheet material is heated to a forming temperature and brought into close proximity to a mold, and a pressure source applies pressure to bring the polymeric thermoplastic sheet material into contact with the mold surface.

[0025] In one or more embodiments, the thermoforming process can be a vacuum forming process, where a vacuum is drawn against the inside of a heated polymeric thermoplastic sheet material through a die, creating a pressure differential with the outside of the sheet exposed to a higher pressure. This pressure differential draws the sheet to the surface of the die. Pressure forming is a process where pressure is applied against a heated sheet from the outside of a mold, causing the sheet to conform to the mold surface.

[0026] In one or more embodiments, the thermoforming process can be a plug-assisted thermoforming process. The plug-assisted thermoforming process may utilize a mechanical plug that contacts the polymeric thermoplastic sheet material to move the sheet into position in combination with vacuum or pressure forming. Matched die forming is a forming method in which two die halves are brought together while applying pressure to a heated polymeric thermoplastic sheet material, causing the material to conform to the shape of each side. In this process, the sheet material is usually larger than the perimeter of the die shape to be formed, and the excess material is later removed.

[0027] Thermoforming can also be applied to thermoset materials to create preforms where the resin softens at high temperatures like thermoplastics, but polymerization remains incomplete. The preform is trimmed and set aside for further processing. The preform is then cured, completing the polymerization of the resin. In another configuration, preforming and polymerization can occur simultaneously in the die.

[0028] In closed mold processes such as injection molding, compression molding, and resin transfer molding (RTM), vacuum can be applied to the die to minimize or eliminate the disruption of resin flow due to air entrapment, thereby improving the quality of molded parts produced in closed mold processes. Air entrapment is a cause of defects in molded parts. The entrapped air can burn along with the vapors released from the thermoplastic sheet material as the flow of material concentrates the vapors under heat and pressure. This process is called dieseling. Tieseling can cause cosmetic defects and excessive wear on the mold. This drawback can be avoided or minimized by one or more embodiment steps of transferring the heated polymeric sheet material from a heating chamber under a supply vacuum range to feed the heated polymeric sheet material to a molding chamber.

[0029] In the compression molding process, the polymer sheet material is placed in the die in the bulk form of a sheet, and the polymer sheet material enters the die under ambient conditions, and the upper and lower die halves are brought together vertically to apply pressure to form a molded article. When a vacuum is applied, a seal is activated when the upper and lower die halves are brought together to form a vacuum in the die. The polymer sheet material is placed and held on the lower die half before the vacuum is created. This process takes time to activate the seal and generate the vacuum as well. If the heated polymer sheet material is not conveyed from the heating chamber under the supply vacuum range to feed it to the molding chamber, the initial contact of the lower die half can trap air between the polymer material and the surface of the lower die half, resulting in surface defects.

[0030] The step of transferring the heated polymer sheet material from the heating chamber under a supply vacuum range to feed the heated polymer sheet material to the molding chamber can reduce or eliminate defects associated with pre-cure. Pre-cure occurs when a thermosetting material begins to harden before the die has fully formed the part, or when the polymer thermoplastic sheet material cools or crystallizes prematurely before the die has fully formed the part. Pre-cure can also occur by the polymer thermoplastic sheet material being in contact with the die too long when the vacuum seal is activated and a vacuum is building. The die can be positioned so that the side with the higher cosmetic requirements is up so that contact with the polymer material is delayed until molding pressure is applied. The adverse effects of this delay can be mitigated by transferring the heated polymer sheet material from the heating chamber under a supply vacuum range to feed the heated polymer sheet material to the molding chamber.

[0031] FIG. 1 is a cutaway perspective view of a system 10 configured to perform a heated polymer sheet material delivery process according to a first embodiment. FIG. 2 is a partial, cross-sectional, side, and partial cross-sectional view of the system 10 shown in FIG. 1 taken along line 2-2 of FIG. 1. The system 10 includes a heating chamber 12 and a forming chamber 14. The heating chamber 12 is configured to increase the temperature of the polymer sheet material and form the heated polymer sheet material. The forming chamber 14 is configured to form a molded article from the heated polymer sheet material. The molded article may be a three-dimensional article that extends substantially in three directions (i.e., the x-axis, the y-axis, and the z-axis).

[0032] The polymer sheet material 16 may be a thermoplastic polymer sheet material or a thermoset polymer sheet material. The polymer sheet material 16 may be formed of a rigid polymer sheet material. The polymer sheet material 16 may be a tape-based laminate, an organic sheet, and a glass mat thermoplastic (GMTex) (e.g., woven fabric and prepreg). The polymer sheet material 16 has an upper surface, a lower surface, and a bulk thickness extending therebetween. The polymer sheet material 16 has an opening 18 disposed about the periphery of the polymer sheet material 16. The opening 18 extends through the bulk thickness of the polymer sheet material 16 and terminates at the upper and lower surfaces of the opening 18.

[0033] As shown in Figures 1 and 2, the polymeric sheet material 16 is placed in a tension frame 20. A spring 22 is attached at one end to the inner periphery of the tension frame 20. The tension frame 20 is rigid and retains its original shape throughout the heating and molding process, forcing the polymeric sheet material 16 to stretch and conform to the shape during the molding process. The free end of the spring 22 is coupled with the opening 18 and configured to couple the polymeric sheet material 16 to the tension frame 20. The spring 22 is configured to pre-tension the polymeric sheet material 16 so that tension is maintained as the polymeric sheet material 16 is moved through the system 10. Depending on the implementation, other tensioning devices may be used. Non-limiting examples of other tensioning devices include flexible elements such as actuators. The tensioning device is configured to apply tension to the polymeric sheet material 16 while allowing the periphery of the polymeric sheet material 16 to be pulled inward or in other directions during the molding process. The tension frame 20 is formed from a rigid material and retains its original shape as the tension frame is pulled through the system 10, thereby allowing the polymeric sheet material 16 to conform to the shape of the molded article. The tension frame 20 containing the polymeric sheet material 16 is transported to the heating chamber 12 along a conveyor (not shown).

[0034] The tension frame 20 containing the polymeric sheet material 16 is conveyed through the inlet port 24 to the heating chamber 12. The inlet port housing 26 is rotatably secured (e.g., using a hinge) to the heating chamber 12 above the inlet port 24 such that the inlet port housing 26 rotates between a closed position 28 and an open position 30. The inlet port housing 26 rotates away from the heating chamber 12 from the closed position 28 to the open position 30. The tension frame 20 containing the polymeric sheet material 16 is conveyed through the inlet port 24 to the heating chamber 12 when the inlet port 26 is in the open position 30. As shown in Figures 1 and 2, an inlet seal 32 is secured to the back side of the inlet port housing 26. The inlet seal 32 is configured to form a seal between the inlet port housing 26 and the heating chamber 12 such that gas does not enter or leave the heating chamber 12 through the inlet port 24. As shown in Figures 1 and 2, the inlet seal 32 is generally rectangular in shape following the periphery of the inlet port housing 26, and the central portion of the inlet port housing 26 is open. In another embodiment, the inlet seal may be sized to the inlet port housing 26, thereby covering the entire back side of the inlet port housing 26. In another embodiment, the inlet seal may be secured to the heating chamber 12 around the periphery of the inlet port 24 instead of, or in addition to, a seal secured to the back side of the inlet port housing 26. The inlet seal 32 may be formed from an elastomeric material, such as a rubber material.

[0035] The heating chamber 12 also has an outlet port 34 opposite the inlet port 24. An outlet port housing 36 is rotatably secured (e.g., using a hinge) to the heating chamber 12 about the outlet port 34 such that the outlet port housing 36 rotates between a closed position 38 and an open position 40. The outlet port housing 36 rotates from the closed position 38 to the open position 40 in a direction away from the heating chamber 12. As shown in FIG. 2, an outlet seal 42 is secured to the back side of the outlet port housing 36. The outlet seal 42 is configured to form a seal between the outlet port housing 36 and the heating chamber 12 such that gas does not enter or leave the heating chamber 12 through the outlet port 34. The outlet seal 42 is generally rectangular in shape following the periphery of the outlet port housing 36, with a central portion of the outlet port housing 36 open. In another embodiment, the outlet seal may be the size of the outlet port housing 36, thereby covering the entire back side of the outlet port housing 36. In another embodiment, the outlet seal may be secured to the heating chamber 12 around the periphery of the outlet port 34 instead of, or in addition to, a seal secured to the back side of the outlet port housing 36. The outlet seal 42 may be formed from an elastomeric material, such as a rubber material.

[0036] As shown in Figures 1 and 2, a single heating chamber 12 is shown. In other embodiments, two or more heating chambers may be utilized in a system implementing a heated polymeric sheet material feed process. After the tension frame 20 containing the polymeric sheet material 16 is conveyed into the heating chamber 12 through the inlet port 24 when the inlet port housing 26 is in the open position 30, the inlet port housing 26 and the outlet port housing 36 seal the inlet port 24 and the outlet port 34 against the inlet seal 32 and the outlet seal 42, respectively, to create a sealed environment within the heating chamber 12 suitable for the heated vacuum conditions within the heating chamber 12.

[0037] The heating chamber 12 includes upper and lower heating elements 44 and 46, and upper and lower heating shields 48 and 50. The upper heating shield 48 is disposed between the upper heating element 44 and an upper wall of the heating chamber 12. The lower heating shield 50 is disposed between the lower heating element 46 and a base 52. The upper and lower heating elements 44 and 46 may be infrared heating elements. In one or more embodiments, the heating chamber 12 may utilize one or more of the following heating methods: forced convection, conduction, and infrared. The upper and lower heating elements 44 and 46 heat the polymeric sheet material 16 to a forming temperature to form a heated polymeric sheet material. Non-limiting examples of molding temperatures can be any one or any two of the following temperatures: 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, and 400° C. The lower end of the range may be suitable for forming prepregs into preforms, while the upper end of the range may be suitable for forming high temperature resins such as liquid crystal polymers. In one embodiment, infrared heat is first applied to dry the polymer sheet material 16 to remove moisture from the polymer sheet material 16. Once the polymeric sheet material 16 is dry, heating of the polymeric sheet material 16 may continue until the desired forming temperature is reached.

[0038] In one embodiment, a vacuum may be applied in the heating chamber 12 prior to heating the polymeric sheet material 16. In another embodiment, a vacuum may be applied in the heating chamber 12 and the forming chamber 14 once the forming temperature is reached. The heated polymeric sheet material may be transported from the heating chamber 12 to the forming chamber 14 under vacuum conditions. A vacuum source 54 is in communication with the heating chamber 12 via a heating chamber conduit 56. The vacuum source 54 is also in communication with the forming chamber 14 via a forming chamber conduit 58. The vacuum source 54 is configured to create a vacuum condition in the heating chamber 12 and the forming chamber 14. By maintaining a vacuum in the heating chamber 12 and the forming chamber 14 and transporting the heated polymeric sheet material therebetween, the amount of heat lost by the heated polymeric sheet material is reduced or eliminated.

[0039] The forming chamber 14 includes an upper platen 60 and a lower platen 61. The forming chamber 14 includes an upright member 64. The forming chamber 14 also includes an upper die half 66 and a lower die half 68 located between the upper platen 60 and the lower platen 61. The upper die half 66 has a negative contour 70 and the lower die half 68 has a positive contour 72. A shroud 74 surrounds the sides of the forming chamber 14. The shroud 74 may be rectangular in shape surrounding the forming chamber 14 on all four sides. The shroud 74 is secured to the lower die half 68 via fasteners 76 and brackets 78 as shown in FIG. 2. The shroud 74 may also be secured to the heating chamber 12. The shroud 74 includes an inlet panel 80 and an outlet panel 82. The upper die half 66 moves up and down inside the shroud 74.

[0040] The molding chamber 14 includes an outlet port 84 that faces the outlet port 34 of the heating chamber 12. The outlet port 84 is formed in the outlet panel 82. An outlet port housing 86 is rotatably secured (e.g., using a hinge) to the molding chamber 14 about the outlet port 84 such that the outlet port housing 86 can rotate between a closed position 88 and an open position 90. As shown in FIG. 2, an outlet seal 92 is secured to the back side of the outlet port housing 86. The outlet seal 92 is configured to form a seal between the outlet port housing 86 and the molding chamber 14 such that gas does not enter or leave the molding chamber 14 through the outlet port 84. The outlet seal 92 is generally rectangular in shape following the periphery of the outlet port housing 86, with a central portion of the outlet port housing 86 open. In another embodiment, the outlet seal may be the size of the outlet port housing 86, thereby covering the entire back side of the outlet port housing 86. In another embodiment, the outlet seal may be secured to the exterior surface of the outlet panel 82 of the shroud 74 around the periphery of the outlet port 84 instead of, or in addition to, a seal secured to the underside of the outlet port housing 86. The outlet seal 92 may be formed of a rubber material.

[0041] The forming chamber 14 may include an upper shroud seal 94 disposed between the upper die half 66 and the shroud 74 and a lower shroud seal 96 disposed between the lower die half 68 and the shroud 74. The upper shroud seal 94 may be secured to an inner surface of the upper die half 66 or the shroud 74. In one or more embodiments, the upper shroud seal 94 is not secured to both the upper die half 66 and the inner surface of the shroud 74 because the upper die half 66 moves up and down relative to the inner surface of the shroud 74. Downward movement is limited to prevent a gap from forming between the upper die half 66 and the shroud 74. The upper shroud seal 94 is configured to form a seal between the shroud 74 and the upper die half 66 to prevent gas from entering or leaving the forming chamber 14 through a gap between the shroud 74 and the upper die half 66. The sliding seal configuration of this embodiment and other embodiments disclosed herein may reduce the volume of the forming chamber 14 or other antechambers disclosed herein. The reduced volume may reduce the time and expense of creating a transfer vacuum in the forming chamber 14 or other forming chambers compared to forming chambers without the sliding seal configuration. In one or more embodiments, the upper shroud seal 94 forms a continuous rectangular perimeter that follows the contour of the shroud 74. The lower shroud seal 96 may be secured to an inner surface of the lower die half 68 and / or the shroud 74. The lower shroud seal 96 is configured to form a seal between the shroud 74 and the lower die half 68 to prevent gas from entering or leaving the forming chamber 14 through a gap between the shroud 74 and the lower die half 68. In one or more embodiments, the lower shroud seal 96 forms a continuous rectangular perimeter that follows the contour of the shroud 74. Upper shroud seal 94 , lower shroud seal 96 , outlet seal 92 , and outlet seal 42 cooperate to prevent gas from entering molding chamber 14 when a vacuum is drawn within molding chamber 14 .

[0042] Once a vacuum is created in the heating chamber 12 within the heating vacuum range and a vacuum is created in the forming chamber 14 within the supply vacuum range, the exit port housing 36 is changed from the closed position 38 to the open position 40 and the tension frame 20 with the polymeric sheet material 16 is transferred from the heating chamber 12 to the forming chamber 14 while maintaining the heating vacuum range and the supply vacuum range. The heating vacuum range and the supply vacuum range may be the same range. In other embodiments, the heating vacuum range and the supply vacuum range may be different. Once the tension frame 20 with the polymeric sheet material 16 is transferred from the forming chamber 14, the exit port housing 36 is changed from the open position 40 to the closed position 38 and the exit port housing 86 remains in the closed position 88 to maintain the supply vacuum range in the forming chamber 14 and the vacuum is then released from the heating chamber 12.

[0043] In the supply vacuum area, the upper die half 66 is lowered and the upper die half 66 and the lower die half 68 are closed on the polymeric sheet material 16, causing the polymeric sheet material to assume the shape of the negative contour 70 and the positive contour 72. A pressure differential may be created in the forming chamber to form the heated polymeric sheet material 16 under pressure differential against the upper die half 66 and / or the lower die half 68. The polymeric sheet material 16 is held under pressure and compression until heat transfer occurs through the upper and lower die halves 66 and 68 to facilitate cooling of the polymeric sheet material 16 and fix the shape of the molded article 98 and reach a target demolding temperature. In one embodiment, the vacuum in the supply vacuum area is released when the target demolding temperature is reached. The vacuum in the supply vacuum area may be released when both exit port housings 36, 68 are in the closed position 38, 88, respectively, and sealed. The upper die half 66 is then raised and the tension frame 20 is lifted away from the lower die half 68. The exit port housing 86 then rotates from a closed position 88 to an open position 90 and the formed article 98 in the tension frame 20 on a conveyor (not shown) is transported from the forming chamber 14 to outside of the forming chamber 14. Once outside of the forming chamber 14, the formed article 98 is removed from the tension frame 20. The tension frame 20 can be reused for new polymeric sheet material 16. Excess material (not shown) around the formed article 98 can be trimmed off in a later processing step. Once the current tension frame 20 has been delivered to the forming chamber 14 under vacuum conditions, the next tension frame 20 with polymeric sheet material can be loaded into the heating chamber 12.

[0044] FIG. 3 is a perspective view of a system 100 configured to perform a heated polymer sheet material supply process according to a second embodiment. FIG. 4 is a partial, cross-sectional, side, and partial cross-sectional view of the system 100 taken along line 4-4 of FIG. 3. As shown in FIG. 3 and / or FIG. 4, the system 100 includes a first heating chamber 102, a second heating chamber 104, and a third heating chamber 106. The first heating chamber 102 is configured to tension a first polymer sheet material 110 via a first inlet port 112 and to receive a first tensioning frame 108 conveyed along a conveyor (not shown). The first tensioning frame 108 is configured to tension the first polymer sheet material 110 via a spring 111 coupled through a first opening 113 of the first polymer sheet material 110. The second heating chamber 104 is configured to tension a second polymer sheet material 116 via a second inlet port 118 and to receive a second tensioning frame 114 conveyed along a second conveyor (not shown). The second tension frame 114 is configured to tension the second polymer sheet material 116 via a second spring 117 coupled through a second opening 119 in the second polymer sheet material 116. The third heating chamber 106 is configured to tension a third polymer sheet material 124 via a third inlet port 126 and receive a third tension frame 122 transported along a third conveyor (not shown). The third tension frame 122 is configured to tension the third polymer sheet material 124 via a third spring 125 coupled through a third opening 127 in the third polymer sheet material 124.

[0045] As shown in FIGS. 3 and 4, the second inlet port housing 128 is rotatably secured (e.g., using a hinge) to the second heating chamber 104 above the second inlet port 118 such that the second inlet port housing 128 rotates between a closed position 130 and an open position 132. The second tension frame 114 having the second polymeric sheet material 116 is conveyed to the second heating chamber 104 through the second inlet port 118 when the second inlet port housing 128 is in the open position 132. As shown in FIG. 4, the second inlet seal 134 is secured to the back side of the second inlet port housing 128. The second inlet seal 134 is configured to form a seal between the second inlet housing 128 and the second heating chamber 104 such that gas does not enter or exit the second heating chamber 104 through the second inlet port 112. The second inlet seal 134 is generally rectangular in shape following the outer periphery of the second inlet port housing 128 and opens at a central portion of the second inlet port housing 128. In another embodiment, the second inlet seal may be sized to the second inlet port housing 128, thereby covering the entire back side of the second inlet port housing 128. In another embodiment, the second inlet seal may be secured to the second heating chamber 104 around the periphery of the second inlet port 118, instead of, or in addition to, a seal secured to the back side of the second inlet port housing 128. The second inlet seal 134 may be formed from an elastomeric material, such as a rubber material.

[0046] The second heating chamber 104 also has a second outlet port 136 opposite the second inlet port 118. A second outlet port housing 138 is rotatably secured (e.g., using a hinge) to the second heating chamber 104 about the second outlet port 136 such that the second outlet port housing 138 rotates between a closed position 140 and an open position 142. The second outlet port housing 138 rotates away from the second heating chamber 104 from the closed position 140 to the open position 142. As shown in FIG. 4, a second outlet seal 144 is secured to the back side of the second outlet port housing 138. The second outlet seal 144 is configured to form a seal between the second outlet port housing 138 and the second heating chamber 104 such that gas does not enter or exit the second heating chamber 104 via the second outlet port 136. The second outlet seal 144 is generally rectangular in shape following the periphery of the second outlet port housing 138, leaving a central portion of the second outlet port housing 138 open. In another embodiment, the second outlet seal may be the size of the second outlet port housing 138, thereby covering the entire back side of the second outlet port housing 138. In another embodiment, the second outlet seal may be secured to the second heating chamber 104 around the periphery of the second outlet port 136 instead of, or in addition to, a seal secured to the back side of the second outlet port housing 138. The second outlet seal 144 may be formed from an elastomeric material, such as a rubber material.

[0047] As shown in FIG. 3, a first inlet port housing 146 is rotatably secured (e.g., using a hinge) to the first heating chamber 102 above the first inlet port 112 such that the first inlet port housing 146 rotates between a closed position 148 and an open position 150. A first tension frame 108 having a first polymeric sheet material 110 is conveyed to the first heating chamber 102 through the first inlet port 112 when the first inlet port housing 146 is in the open position 150. A first inlet seal (not shown) may be secured to a back side of the first inlet port housing 146. The first inlet seal is configured to form a seal between the first inlet port housing 146 and the first heating chamber 102 such that gas does not enter or leave the first heating chamber 102 through the first inlet port 112. The first inlet seal is generally rectangular in shape following the periphery of the first inlet port housing 146 and is open at a central portion of the first inlet port housing 146. In another embodiment, the first inlet seal may be sized to the first inlet port housing 146, thereby covering the entire back side of the first inlet port housing 146. In another embodiment, the first inlet seal may be secured to the first heating chamber 102 around the periphery of the first inlet port 112, instead of or in addition to a seal secured to the back side of the first inlet port housing 146. The first inlet seal may be formed from an elastomeric material, such as a rubber material.

[0048] The first heating chamber 102 also has a first outlet port 152 opposite the first inlet port 112. A first outlet port housing 154 is rotatably secured (e.g., using a hinge) to the first heating chamber 102 about the first outlet port 152 such that the first outlet port housing 154 rotates between a closed position 156 and an open position 158. The first outlet port housing 154 rotates away from the first heating chamber 102 from the closed position 156 to the open position 158. A first outlet seal (not shown) may be secured to a back side of the first outlet port housing 154. The first outlet seal is configured to form a seal between the first outlet port housing 154 and the first heating chamber 102 such that gas does not enter or exit the first heating chamber 102 through the first outlet port 152. The first outlet seal is generally rectangular in shape to fit the periphery of the first outlet port housing 154 and opens at a central portion of the first outlet port housing 154. In another embodiment, the first exit seal may be sized to the first exit port housing 154, thereby covering the entire back side of the first exit port housing 154. In another embodiment, the first exit seal may be secured to the first heating chamber 102 around the periphery of the first exit port 152, instead of, or in addition to, a seal secured to the back side of the first exit port housing 154. The first exit seal may be formed from an elastomeric material, such as a rubber material.

[0049] As shown in FIG. 3 , a third inlet port housing 160 is rotatably secured (e.g., using a hinge) to the third heating chamber 106 above the third inlet port 126 such that the third inlet port housing 160 rotates between a closed position 162 and an open position 164. The third tension frame 122 having the third polymeric sheet material 124 is conveyed to the third heating chamber 106 through the third inlet port 126 when the third inlet port housing 160 is in the open position 164. A third inlet seal (not shown) may be secured to the back side of the third inlet port housing 160. The third inlet seal is configured to form a seal between the third inlet port housing 160 and the third heating chamber 106 such that gas does not enter or leave the third heating chamber 106 through the third inlet port 126. The third inlet seal is generally rectangular in shape following the periphery of the third inlet port housing 160 and is open at a central portion of the third inlet port housing 160. In another embodiment, the third inlet seal may be sized to the third inlet port housing 160, thereby covering the entire back side of the third inlet port housing 160. In another embodiment, the third inlet seal may be secured to the third heating chamber 106 around the periphery of the third inlet port 126 instead of, or in addition to, a seal secured to the back side of the third inlet port housing 160. The third inlet seal may be formed from an elastomeric material, such as a rubber material.

[0050] The third heating chamber 106 also has a third outlet port 166 opposite the third inlet port 126. A third outlet port housing 168 is rotatably secured (e.g., using a hinge) to the third heating chamber 106 about the third outlet port 166 such that the third outlet port housing 168 rotates between a closed position 170 and an open position 172. The third outlet port housing 168 rotates away from the third heating chamber 106 from the closed position 170 to the open position 172. A third outlet seal (not shown) may be secured to a back side of the third outlet port housing 168. The third outlet seal is configured to form a seal between the third outlet port housing 168 and the third heating chamber 106 such that gas does not enter or exit the third heating chamber 106 through the third outlet port 166. The third outlet seal is generally rectangular in shape following the periphery of the third outlet port housing 168 and opens at a central portion of the third outlet port housing 168. In another embodiment, the third exit seal may be sized to the third exit port housing 168, thereby covering the entire back side of the third exit port housing 168. In another embodiment, the third exit seal may be secured to the third heating chamber 106 around the periphery of the third exit port 166, instead of, or in addition to, a seal secured to the back side of the third exit port housing 168. The first exit seal may be formed from an elastomeric material, such as a rubber material.

[0051] As described above, the system 100 includes the first heating chamber 102, the second heating chamber 104, and the third heating chamber 106. The following describes the components and operation of the second heating chamber 104 according to one embodiment as shown in FIG. 3 and FIG. 4. This description may be applied to the similar components and operation of the first heating chamber 102 and / or the third heating chamber 106. As shown in FIG. 3 and FIG. 4, when the second inlet port housing 128 is in the open position 132, after the second tension frame 114 having the second polymeric sheet material 116 is conveyed into the second heating chamber 104 through the second inlet port 118, the second inlet port housing 132 and the second outlet port housing 138 seal the second inlet port 118 and the second outlet port 136 against the second inlet seal 134 and the second outlet seal 144, respectively, to form a sealed environment of the second heating chamber 104 suitable for heating vacuum conditions within the second heating chamber 104.

[0052] As shown in FIG. 4, the second heating chamber 104 includes second upper and lower heating elements 174 and 176, and second upper and lower heating shields 178 and 180. The second upper heating shield 178 is disposed between the second upper heating element 174 and the upper wall of the second heating chamber 104. The second lower heating shield 180 is disposed between the second lower heating element 176 and the second base 182. The second upper and lower heating elements 174 and 176 can be infrared heating elements. In one or more embodiments, the second heating chamber 104 can use one or more heating methods of convection heat, conductive heat (e.g., conductive heat generated from an isobaric double belt press), electromagnetic heat, and / or radiant heat (e.g., infrared radiation heat). The second upper and lower heating elements 174 and 176 heat the second polymer sheet material 116 to a forming temperature to form a heated polymer sheet material. Non-limiting examples of molding temperatures can be any one or within any two of the following temperatures: 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, and 400°C.

[0053] Once the forming temperature has been reached, a vacuum may be applied within the second heated chamber 104 and the forming chamber 184. The heated polymeric sheet material may be transferred under vacuum conditions. As shown in FIG. 4, a vacuum source 186 is in communication with the second heated chamber 104 via a second heated chamber conduit 188. The vacuum source 186 is also in communication with the forming chamber 184 via a forming chamber conduit 190. The vacuum source 186 is configured to create a vacuum within the heated chamber 104 and the forming chamber 184. By maintaining a vacuum within the second heated chamber 104 and the forming chamber 184 and transferring the heated polymeric sheet material therebetween, the amount of heat lost by the heated polymeric sheet material is reduced or eliminated.

[0054] In one embodiment, the system 100 is configured to sequentially heat the first polymer sheet material 110, the second polymer sheet material 116, and the third polymer sheet material 124 in the first heating chamber 102, the second heating chamber 104, and the third heating chamber 106, respectively, to obtain the first, second, and third heated polymer sheet materials, respectively. The sequential feeding steps of the three heating chamber configurations of Figures 3 and 4 allow for a greater throughput of formed articles than a single heating chamber configuration, for example, when the forming time is shorter than the heating time. In one embodiment, the first polymer sheet material 110 is heated to a forming temperature in the enclosed first heating chamber 102 to form the first heated polymer sheet material. Upon reaching the forming temperature, a vacuum is simultaneously formed in the enclosed first heating chamber 102 and the enclosed forming chamber 184. After the vacuum is formed, the first heated polymer sheet is transferred to the forming chamber 184, which is configured to form the first heated polymer sheet into a first formed article under vacuum conditions, and then exits the forming chamber 184.

[0055] As and / or before the first heated polymer sheet is formed into the first article in the forming chamber 184, the second polymer sheet material 116 can be heated in the enclosed second heated chamber 104 while the first heated chamber 102 is loaded with fresh first polymer sheet material 110. Once the first article leaves the forming chamber 184 and the second polymer sheet material 116 has reached the forming temperature, a vacuum can be created simultaneously in the second heated chamber 104 and the forming chamber 184 using a vacuum source 186. After the vacuum is created, the second heated polymer sheet is transferred to the forming chamber 184 where it is formed into the second article under vacuum conditions before exiting the forming chamber 184.

[0056] As and / or before the second heated polymer sheet is formed into a second molded article in the forming chamber 184, a third polymer sheet material 124 can be heated in the enclosed third heated chamber 106 while the second heated chamber 104 is loaded with fresh second polymer sheet material 116. Once the second molded article exits the forming chamber 184 and the third polymer sheet material 124 reaches the forming temperature, a vacuum can be simultaneously formed in the third heated chamber 106 and the forming chamber 184 using a vacuum source 186. After the vacuum is formed, the third heated polymer sheet is transferred to the forming chamber 184 where it is formed under vacuum conditions into a third molded article before exiting the forming chamber 184. In one embodiment, this continuous process is repeated using the system 100.

[0057] The forming chamber 184 includes an upper platen 192 configured to move over an upright member 198 and a press bed 194. The forming chamber 184 also includes an upper die half 198 and a lower die half 200 positioned between the upper platen 192 and the press bed 194. The upper die half 198 has a negative contour 202 and the lower die half 200 has a positive contour 204. A shroud 206 surrounds the sides of the forming chamber 184. The shroud 206 may be rectangular in shape surrounding the forming chamber 184 on all four sides. The shroud 206 is secured to the lower die half 200 via fasteners 208 and brackets 210 as shown in FIG. 4. The shroud 206 may also be secured to one or more of the first heating chamber 102, the second heating chamber 104, and the third heating chamber 106. The shroud 206 includes an inlet panel 212 and an outlet panel 209. The upper die half 198 moves up and down within the shroud 206.

[0058] The forming chamber 184 has an outlet port 216 facing the second outlet port 136 of the second heating chamber 104. The outlet port 216 is formed in the outlet panel 214. An outlet port housing 218 is rotatably secured (e.g., using a hinge) to the forming chamber 184 about the outlet port 216 such that the outlet port housing 218 can rotate between a closed position 220 and an open position 222. As shown in FIG. 4, an outlet seal 224 is secured to the back side of the outlet port housing 218. The outlet seal 224 is configured to form a seal between the outlet port housing 218 and the forming chamber 184 such that gas does not enter or leave the forming chamber 184 through the outlet port 216. The outlet seal 224 is generally rectangular in shape following the periphery of the outlet port housing 218, with a central portion of the outlet port housing 218 open. In another embodiment, the outlet seal may be the size of the outlet port housing 218, thereby covering the entire back side of the outlet port housing 218. In another embodiment, the outlet seal may be secured to the outer surface of the outlet panel 214 of the shroud 206 around the periphery of the outlet port 216 instead of, or in addition to, a seal secured to the underside of the outlet port housing 218. The outlet seal 224 may be formed of a rubber material.

[0059] The forming chamber 184 may include an upper shroud seal 226 disposed between the upper die half 198 and the shroud 206 and a lower shroud seal 228 disposed between the lower die half 200 and the shroud 206. The upper shroud seal 226 may be secured to an inner surface of the upper die half 198 or the shroud 206. In one or more embodiments, the upper shroud seal 226 is not secured to both the upper die half 198 and the inner surface of the shroud 206 because the upper die half 198 moves up and down relative to the inner surface of the shroud 206. Downward movement is limited to prevent a gap from forming between the upper die half 198 and the shroud 206. The upper shroud seal 226 is configured to form a seal between the shroud 206 and the upper die half 198 to prevent gas from entering or exiting the forming chamber 184 through a gap between the shroud 206 and the upper die half 198. In one or more embodiments, the upper shroud seal 226 forms a continuous rectangular perimeter that follows the contour of the shroud 206. The lower shroud seal 228 may be secured to an inner surface of the lower die half 200 and / or the shroud 206. The lower shroud seal 228 is configured to form a seal between the shroud 206 and the lower die half 200 to prevent gas from entering or exiting the forming chamber 184 through a gap between the shroud 206 and the lower die half 200. In one or more embodiments, the lower shroud seal 228 forms a continuous rectangular perimeter that follows the contour of the shroud 206. The upper shroud seal 226 , the lower shroud seal 228 , the outlet seal 224 , and the second outlet seal 144 cooperate to prevent gas from entering the molding chamber 184 when a vacuum is drawn within the molding chamber 184 .

[0060] Once a vacuum within the heating vacuum range is created in the second heating chamber 104 (or other heating chamber shown in FIG. 3) and a vacuum within the supply vacuum range is created in the forming chamber 184, the second exit port housing 138 (or other exit port housing shown in FIG. 3) is changed from a closed position 140 to an open position 142 (or other exit port housing open and closed positions shown in FIG. 3) and the second tension frame 114 with the second polymer sheet material 116 (or other tension frame with polymer sheet material shown in FIG. 3) is transferred from the second heating chamber 104 (or other heating chamber shown in FIG. 3) to the forming chamber 184 while maintaining the heating vacuum range and the supply vacuum range. The heating vacuum range and the supply vacuum range can be the same range. In other embodiments, the heating vacuum range and the supply vacuum range can be different. When the tension frame 114 with the second polymeric sheet material 116 is removed from the forming chamber 184, the second outlet port housing 138 is changed from the open position 142 to the closed position 140 and the outlet port housing 218 remains in the closed position 220 to maintain the applied vacuum range within the forming chamber 184, and then the vacuum is released from the third heating chamber 106.

[0061] In the supply vacuum range, the upper die half 198 is lowered and the upper die half 198 and the lower die half 200 are closed onto the first, second, or third polymeric sheet material 110, 116, or 124 such that the polymeric sheet material assumes the shape of the negative contour 202 and the positive contour 204. The first, second, or third polymeric sheet material 110, 116, or 124 is held under pressure and compression until heat transfer occurs through the upper and lower die halves 198 and 200 to facilitate cooling of the first, second, or third polymeric sheet material 110, 116, or 124 to set the shape of the molded article 230 and reach a target demolding temperature. In one embodiment, the vacuum in the supply vacuum range is released when the target demolding temperature is reached. The vacuum in the supply vacuum range can be released when both outlet port housings 138, 218 are in the closed position 140, 220, respectively, and sealed. The upper die half 198 is then raised, lifting the first, second or third tension frame 108, 114 or 122 out of the lower die half 200. The exit port housing 218 then rotates from a closed position 220 to an open position 222, and the molded article 230 in the first, second or third tension frame 108, 114 or 122 on a conveyor (not shown) is transported out of the molding chamber 184. Once outside the molding chamber 184, the molded article 230 is removed from the first, second or third tension frame 108, 114 or 122. Excess material (not shown) around the molded article 230 may be trimmed off in a later processing step.

[0062] FIG. 5 is a cutaway perspective view of system 250. FIG. 6 is a partial, cutaway, side and partial cross-sectional view of system 250 shown in FIG. 5 taken along line 6-6 of FIG. 5. System 250 includes a first heating chamber 252, a second heating chamber 254, and a third heating chamber 256. First heating chamber 252 may be configured to function as a heating zone and / or an air lock. The structure and operation of first, second and third heating chambers 252, 254 and 256 may be the same as that shown and described with respect to heating chamber 12. First, second and third heating chambers 252, 254 and 256 are connected to each other and vacuum conditions may be maintained individually within each heating chamber 252, 254 and 256, adjacent heating chambers (e.g., heating chambers 252 and 254, or heating chambers 254 and 256), or all three heating chambers. The advantage of the first, second, and third heating chamber configuration is that multiple zones increase throughput. For example, if it takes 3 minutes to heat and 1 minute to form, three consecutive heating zones provide a 3 minute residence time to support the 1 minute forming time.

[0063] As shown in Figures 5 and 6, first and second polymer sheet materials 258 and 260 are placed on a conveyor 262. The first and second polymer sheet materials 258 and 260 may be formed of a flowable bulk material such as GMT or sheet molding compound (SMC). The first polymer sheet material 258 may be placed in the first heated chamber 252. The second polymer sheet material 260 may be placed in the second heated chamber 254. The third polymer sheet material may be placed in the third heated chamber 256. In this configuration, the three polymer sheet materials may be heated to a forming temperature simultaneously. After reaching the forming temperature, a vacuum may be applied to all three heated chambers 252, 254, 256.

[0064] A vacuum source 290 is in communication with the first, second, and third heated chambers 252, 254, and 256 via first, second, and third vacuum conduits 292, 294, and 296, respectively. The vacuum source 290 is also in communication with the forming chamber 276 via a forming chamber conduit 298. The vacuum source 290 is configured to create a vacuum in the first, second, and / or third heated chambers 252, 254, and / or 256 simultaneously, sequentially, or at different times. By maintaining a vacuum in the first heated chamber 252 and the second heated chamber 254 and transferring the heated polymer sheet material therebetween, the amount of heat lost by the heated polymer sheet is reduced or eliminated.

[0065] Once the forming temperature is reached and vacuum conditions are established, the third heated chamber 256 is opened to the forming chamber 276 and the third polymer sheet material can be transferred under vacuum conditions from the third heated chamber 256 through the forming chamber inlet port 302 to the forming chamber 276 with the forming chamber inlet port housing 300 in the open position 305 and the third inlet port housing 284 in the closed position 288. By maintaining vacuum conditions in the third heated chamber 256 and the forming chamber 276 and transferring the heated polymer sheet material therebetween, the amount of heat lost by the heated polymer sheet can be reduced or eliminated.

[0066] Once the third polymer sheet material is transferred to the forming chamber 276, the forming chamber inlet port housing 300 is altered to the closed position 304, the third inlet port housing 284 is altered to the open position, and the second inlet port housing 280 is maintained in the closed position 282. In this configuration, the second polymer sheet material 260 can be transferred from the second heated chamber 254 to the third heated chamber 256 under vacuum conditions (and then transferred to the forming chamber 276 under vacuum conditions). Once the second polymer sheet material 260 is transferred to the third heated chamber 256, the third inlet port housing 284 is altered to the closed position 282, and the inlet port housing 270 is maintained in the closed position 272. In this configuration, the first polymer sheet material 258 can be transferred from the first heated chamber 252 through the second inlet port 278 to the second heated chamber 254 under vacuum conditions (and then transferred to the third heated chamber 256 and the forming chamber 276 under vacuum conditions). Once the first polymer sheet material 258 has been transferred to the second heated chamber 254, the second inlet port housing 280 is altered to a closed position 282 and the inlet port housing 270 is altered to an open position 274 so that a fourth polymer sheet material can be placed into the first heated chamber 252 via the first inlet port 268 and the sequence of heating, applying a vacuum, and transferring the heated polymer sheet material under vacuum can be repeated.

[0067] The forming chamber 276 includes an upper platen 306 and a lower platen 308. The forming chamber 276 includes an upright member 310. The forming chamber 276 also includes an upper die half 312 and a lower die half 314 located between the upper platen 306 and the lower platen 308. The upper die half 312 has a negative contour 316 and the lower die half 314 has a positive contour 318. A shroud 320 surrounds the sides of the forming chamber 276. The shroud 320 may be rectangular in shape surrounding the forming chamber 276 on all four sides. The shroud 320 is secured to the lower die half 314 via fasteners 322 and brackets 324 as shown in FIG. 6. The shroud 320 may be secured to the third heating chamber 256. The shroud 320 includes an inlet panel 326 and an outlet panel 328. The upper die half 312 moves up and down inside the shroud 320 .

[0068] The forming chamber 276 has an outlet port 330 facing the forming chamber inlet port 302. The outlet port 330 is formed in the outlet panel 328. An outlet port housing 332 is rotatably secured (e.g., using a hinge) to the forming chamber 276 about the outlet port 330 such that the outlet port housing 332 can rotate between a closed position 334 and an open position 336. As shown in FIG. 6, an outlet seal 338 is secured to the back side of the outlet port housing 332. The outlet seal 338 is configured to form a seal between the outlet port housing 332 and the forming chamber 276 such that gas does not enter or leave the forming chamber 276 through the outlet port 330. The outlet seal 338 is generally rectangular in shape following the periphery of the outlet port housing 332, with a central portion of the outlet port housing 332 open. In another embodiment, the outlet seal may be the size of the outlet port housing 332, thereby covering the entire back side of the outlet port housing 332. In another embodiment, the outlet seal may be secured to the outer surface of the outlet panel 328 of the shroud 320 around the periphery of the outlet port 330 instead of, or in addition to, a seal secured to the underside of the outlet port housing 332. The outlet seal 338 may be formed of a rubber material.

[0069] The forming chamber 276 may include an upper shroud seal 340 disposed between the upper die half 312 and the shroud 320 and a lower shroud seal 342 disposed between the lower die half 314 and the shroud 320. The upper shroud seal 340 may be secured to an inner surface of the upper die half 312 or the shroud 320. In one or more embodiments, the upper shroud seal 340 is not secured to both the upper die half 312 and the inner surface of the shroud 320 because the upper die half 312 moves up and down relative to the inner surface of the shroud 320. Downward movement is limited to prevent a gap from forming between the upper die half 312 and the shroud 320. The upper shroud seal 340 is configured to form a seal between the shroud 320 and the upper die half 312 to prevent gas from entering or exiting the forming chamber 276 through a gap between the shroud 320 and the upper die half 312. In one or more embodiments, the upper shroud seal 340 forms a continuous rectangular perimeter that follows the contour of the shroud 320. The lower shroud seal 342 may be secured to the lower die half 314 and / or the inner surface of the shroud 320. The lower shroud seal 342 is configured to form a seal between the shroud 320 and the lower die half 314 to prevent gas from entering or exiting the forming chamber 276 through a gap between the shroud 320 and the lower die half 314. In one or more embodiments, the lower shroud seal 342 forms a continuous rectangular perimeter that follows the contour of the shroud 320. The upper shroud seal 340, the lower shroud seal 342, the outlet seal 338, and the forming chamber inlet seal cooperate to prevent gas from entering the forming chamber 276 when a vacuum is drawn within the forming chamber 276.

[0070] Once a vacuum within the heating vacuum range is formed in the third heated chamber 256 and a vacuum within the supply vacuum range is formed in the forming chamber 276, the forming chamber inlet port housing 300 is changed from the closed position 304 to the open position and the third polymeric sheet material is transferred from the third heated chamber 256 to the forming chamber 276 while maintaining the heating vacuum range and the supply vacuum range. The heating vacuum range and the supply vacuum range may be the same range. In other embodiments, the heating vacuum range and the supply vacuum range may be different. Once the third polymeric sheet material is transferred from the forming chamber 276, the forming chamber inlet port housing 300 is changed from the open position to the closed position 304 and the outlet port housing 332 remains in the closed position 334 to maintain the supply vacuum range in the forming chamber 276.

[0071] In the supply vacuum area, the upper die half 312 is lowered and the upper die half 312 and the lower die half 314 are closed onto the polymer sheet material 258, causing the polymer sheet material to assume the shape of the negative contour 316 and the positive contour 318. The polymer sheet material is held under pressure and compression until heat transfer occurs through the upper and lower die halves 312 and 314 to facilitate cooling of the polymer sheet material 258, setting the shape of the molded article 344, and reaching a target demolding temperature. In one embodiment, the vacuum in the supply vacuum area is released when the target demolding temperature is reached. The vacuum in the supply vacuum area may be released when the exit port housings 300, 332 are in the closed positions 304, 334, respectively, and sealed. The upper die half 312 is then raised, lifting the polymer sheet material and releasing the lower die half 314. The exit port housing 332 then rotates from a closed position 334 to an open position 336 and the molded article 344 on a conveyor (not shown) is transported from the molding chamber 276 to outside of the molding chamber 276. Excess material (not shown) around the molded article 344 can be trimmed away in a later processing step.

[0072] 7 illustrates a cross-sectional view, a side view, and a partial cross-sectional view of a system 350 according to another embodiment. System 350 is an alternative to system 250. Both systems 250 and 350 include first, second, and third heating chambers 252, 254, and 256. System 350 includes a molding chamber 352, while system 250 includes a molding chamber 276.

[0073] The forming chamber 352 includes a press bed 354 and a press crown 356. In one or more embodiments, this configuration can eliminate any sliding seals to maintain a vacuum. The forming chamber 352 also includes a shroud 358. In one embodiment, the press bed 354 and the press crown 356 are fixed to the shroud 358, such that the press bed 354 and the press crown 356 are stationary and form a seal against the shroud 358. In one embodiment, the press bed 354 and the press crown 356 have the same profile and are sealed against the shroud 358, which has a regular profile. The press bed 354, the press crown 356, and the shroud 358 are configured to form a vacuum chamber 360 within the forming chamber 352. The vacuum chamber 360 can be formed without sliding seals that are prone to wear and leaks. The shroud 358 can be fixed to the third heating chamber 256. The third heating chamber 256 may be configured to heat and transport the polymeric sheet material 260 under vacuum conditions to the forming chamber 352. The shroud 358 includes an inlet panel 368 and an outlet panel 370.

[0074] The forming chamber 352 also includes an upper platen 362 and a lower platen 364 located between the press bed 354 and the press crown 356. Upper and lower die halves 376, 378 are secured to the upper and lower platens 362, 364, respectively. The forming chamber 352 also includes an upright member 366. The upper die half 376 moves up and down inside the shroud 358 on the upright member 366. The upper die half 376 has a negative profile 372 and the lower die half 378 has a positive profile 374.

[0075] The system 350 also includes an exit vacuum chamber 290. The exit vacuum chamber 290 (e.g., an airlock) is configured to receive the molded article 344 being transferred from the molding chamber 352. As shown in FIG. 7, the exit vacuum chamber 290 is external to the molding chamber 352 and is coupled to a shroud 358 of the molding chamber 352. The vacuum chamber 290 can be set to a pressure between atmospheric pressure and vacuum pressure using a vacuum conduit 378 and a vacuum source 290. This configuration allows the molded article 344 to be transferred from the molding chamber 352 without fully depressurizing the molding chamber 352, which can increase the time and expense associated with creating a subsequent vacuum in the molding chamber 352. As shown in FIG. 7, the molded article 344 exits the vacuum chamber 290 through an exit port 380.

[0076] 8 illustrates a cross-sectional view, a side view, and a partial cross-sectional view of a system 400 according to another embodiment. The system 400 includes a heating / forming chamber 402 (e.g., an autoclave combined with a press), an entry airlock 401, and an exit airlock 403. The entry airlock 401 includes a port 405 configured to receive polymeric sheet material 410. The entry airlock 401 communicates with the heating / forming chamber 402 through port 412. The exit airlock 403 includes a port 407 configured to eject a molded article 436 from the exit airlock 403. The exit airlock 403 communicates with the heating / forming chamber 402 through port 413.

[0077] In one embodiment, the volume of the heating / forming chamber 402 is significantly larger than the volume of the entry airlock 401 and the exit airlock 403. In one embodiment, when the ports 412 and 413 are closed and sealed, a vacuum is created in the large volume of the thermoforming chamber 402 by the vacuum source 404. In one or more embodiments, the vacuum condition can be an inert environment. Initially, the entry airlock 401 is at external ambient atmospheric conditions to introduce the polymer sheet material 410. Then, after the polymer sheet 410 is introduced into the entry airlock 401 and the ports 405 and 412 are closed, a vacuum is created in the entry airlock 401 by the vacuum source 404. Once the vacuum is created in the entry airlock 401, the port 412 is opened and the polymer sheet 410 is transported from the entry airlock 401 to the heating / forming chamber 402, thereby maintaining the vacuum in the heating / forming chamber 402. Vacuum conditions are maintained by vacuum source 404 while part 436 is formed in forming zone 408. Part 436 is transferred under vacuum conditions to exit airlock 403 through port 413 in the open position, thereby maintaining vacuum conditions within heating / forming chamber 402. Port 413 is then closed, conditions within discharge airlock 403 are stabilized by external ambient conditions, and port 407 is opened to release part 436 from exit airlock 403.

[0078] The heating / forming chamber 402 includes a heating zone 406 and a forming zone 408. The heating zone 406 is configured to increase the temperature of a polymeric sheet material 410 that is fed into the heating / forming chamber 402 via a port 412. The heating zone 406 includes upper and lower heating elements 414 and 416, as well as upper and lower heat shields 418 and 420. The upper and lower heating elements 414 and 416 heat the polymeric sheet material 410 to a forming temperature to form the heated polymeric sheet material.

[0079] The heated polymeric sheet material may be transported under vacuum conditions from the heating zone 406 to the forming zone 408. By maintaining a vacuum in the heating / forming chamber 402 while transferring the heated polymeric sheet material between the heating zone 406 and the forming zone 408, the amount of heat lost by the heated polymeric sheet material may be reduced or eliminated. Maintaining a vacuum during the forming process may reduce and / or eliminate cosmetic defects in the molded part and / or the possibility of mold degradation due to trapped gas.

[0080] The forming zone 408 comprises a press bed 421 and a press crown 422 that are fixed to the heating / forming chamber 402 so that the press bed 421 and press crown 422 are stationary relative to the heating / forming chamber 402 and form a seal suitable for vacuum conditions.

[0081] The forming zone 408 also includes an upper platen 424 and a lower platen 426 located between the press bed 421 and the press crown 422. Upper and lower die halves 428, 430 are secured to the upper and lower platens 424, 426, respectively. The forming zone 408 also includes an upright member 431. The upper die half 428 moves up and down on the upright member 431. The upper die half 428 has a negative profile 432 and the lower die half 430 has a positive profile 434. The port 413 is configured to discharge the formed article 436 into the exit airlock 403 as the formed article 436 is transferred from the forming zone 408.

[0082] The heating element, the port, the port housing, and the components of the molding chamber may be operated by a controller. The controller may include a processor, which may be any suitable processing device or set of processing devices, such as a microprocessor, a microcontroller-based platform, an integrated circuit, one or more field programmable gate arrays (FPGAs), and / or one or more application specific integrated circuits (ASICs). In one or more embodiments, a memory is in communication with the controller. The memory may be a volatile memory (e.g., RAM including non-volatile RAM, magnetic RAM, ferroelectric RAM, etc.), a non-volatile memory (e.g., disk memory, FLASH memory, EPROM, EEPROM, memristor-based non-volatile solid-state memory, etc.), a non-alterable memory (e.g., EPROM), a read-only memory, and / or a mass storage device (e.g., hard drive, solid-state drive, etc.). In some examples, the memory may include multiple types of memory, particularly volatile memory and non-volatile memory. The memory may be a computer-readable medium in which one or more sets of instructions, such as software, for operating the methods of the present disclosure are embedded. The instructions may embody one or more of the methods or logic described herein. For example, the instructions may reside, completely or at least partially, in one or more of a memory, a computer-readable medium, and / or a controller during execution of the instructions.

[0083] Although exemplary embodiments have been described above, these embodiments are not intended to describe all possible forms of the present invention. Rather, the terms used herein are terms of description rather than limitation, and it will be understood that various modifications may be made without departing from the spirit and scope of the present invention. Furthermore, features of various embodiments may be combined to form further embodiments of the present invention.

Claims

1. 1. A polymeric sheet material forming process comprising: a first heating step of heating a first polymer sheet to a first forming temperature in a first heating zone under a heating vacuum range to form a first heated polymer sheet material; a first transfer step of transferring the first heated polymeric sheet material from the first heating zone under a supply vacuum range to provide the first heated polymeric sheet material to a forming zone under a supply vacuum range; forming the first heated polymeric sheet material into a first molded article in the forming zone; a second heating step of heating the second polymer sheet to a second forming temperature in a second heating zone, the second heating zone being different from the first heating zone, under a heated vacuum range to form a second heated polymer sheet material; a second transfer step of transferring the second heated polymeric sheet material from the second heating zone under a supply vacuum range after the first molded article has left the forming zone to supply the second heated polymeric sheet material to the forming zone under a supply vacuum range; forming said second heated polymer sheet material into a second article in said forming zone.

2. 10. The heated polymeric sheet material forming process of claim 1, wherein said second heating step is initiated during or before said first forming step.

3. 10. The heated polymeric sheet material forming process of claim 1, wherein a portion of said first and second heating steps occur simultaneously.

4. 2. The heated polymeric sheet material forming process of claim 1, further comprising the step of forming a supply vacuum area simultaneously in the second heating zone and in the forming zone after the first formed article exits the forming zone.

5. 10. The heated polymeric sheet material forming process of claim 1, wherein the first and second heating zones are connected in parallel to the forming zone.

6. 2. The heated polymeric sheet material forming process of claim 1, wherein said second transferring step comprises transferring said second heated polymeric sheet material from said second heating zone through said first heating zone to said forming zone.

7. 7. The heated polymeric sheet material forming process of claim 6, further comprising the step of forming a supply vacuum area simultaneously in said first heating zone and in said forming zone after said first formed article exits said forming zone.

8. 2. The heated polymeric sheet material forming process of claim 1, wherein said first and second heating zones are connected in series and said first heating zone and said forming zone are connected in series.

9. 10. The heated polymeric sheet material forming process of claim 1, wherein said first and / or second formed articles are said first and / or second decorative automotive articles.

10. 10. The polymeric sheet material forming process of claim 1, wherein said forming step is performed using a closed mold process.

11. 11. The polymeric sheet material molding process of claim 10, wherein the closed mold process is selected from the group consisting of an injection molding process, a compression molding process, a resin transfer molding (RTM) process, and combinations thereof.

12. 1. A rigid thermoplastic polymer sheet material molding process comprising: heating the rigid thermoplastic polymer sheet in a heating zone under a heated vacuum range to a molding temperature to form a heated rigid thermoplastic polymer sheet material; conveying the heated rigid thermoplastic polymer sheet material from the heating zone under a supply vacuum to deliver the heated rigid thermoplastic polymer sheet material to a forming zone under a supply vacuum; forming said heated rigid thermoplastic sheet material into a molded article in said forming zone.

13. 13. The rigid thermoplastic polymer sheet material molding process of claim 12, wherein said forming step is performed using a thermoforming process.

14. 14. The rigid thermoplastic polymer sheet material molding process of claim 13, wherein said thermoforming process is selected from the group consisting of a vacuum forming process, a pressure forming process, a plug assist molding process, a matched die molding process, and combinations thereof.

15. 13. The rigid thermoplastic polymer sheet material molding process of claim 12 further comprising the step of transferring the molded article from the forming zone under ambient or inert atmosphere.

16. 13. The rigid thermoplastic polymer sheet material molding process of claim 12, wherein said molding step is performed using a closed mold process.

17. 17. The rigid thermoplastic polymer sheet material molding process of claim 16, wherein the closed mold process is selected from the group consisting of an injection molding process, a compression molding process, a resin transfer molding (RTM) process, and combinations thereof.

18. 13. The rigid thermoplastic polymer sheet material molding process of claim 12, wherein said forming zone is a forming chamber, and further comprising maintaining a supply vacuum range within said forming zone throughout the first and second molding cycles.

19. 13. The rigid thermoplastic polymer sheet material molding process of claim 12, wherein the forming zone is a forming chamber including a shroud, a crown, and a bed, the crown and the bed being fixedly connected to the shroud to enclose the forming chamber.

20. 13. The rigid thermoplastic polymer sheet material molding process of claim 12, wherein the heating step includes heating the polymer sheet in the heating zone with a heat source.

21. 21. The rigid thermoplastic polymer sheet material molding process of claim 20, wherein the heat source is selected from the group consisting of a conductive heat source, an electromagnetic heat source, a radiant heat source, and combinations thereof.

22. 13. The rigid thermoplastic polymer sheet material molding process of claim 12, wherein the heated rigid thermoplastic polymer sheet material is a flowable polymer sheet material at molding temperatures.

23. 13. The rigid thermoplastic polymer sheet material molding process of claim 12, wherein the rigid thermoplastic polymer sheet comprises multiple layers and / or plies.

24. 13. The method of claim 12, wherein the polymer sheet is gripped at one or more edges of the polymer sheet.

25. 13. The rigid thermoplastic polymer sheet material molding process of claim 12, wherein the step of transferring under a supply vacuum reduces heat loss from a surface of the heated rigid thermoplastic polymer sheet material compared to transferring under ambient conditions.

26. 13. The rigid thermoplastic polymer sheet material molding process of claim 12, wherein the molded article is a decorative automotive item.

27. 1. A heated polymer sheet material forming process comprising: heating the polymer sheet to a forming temperature in a heating zone within a single chamber containing a forming zone under vacuum to form a heated polymer sheet material; conveying the heated polymeric sheet material from the heating zone under vacuum to deliver the heated polymeric sheet material to a forming zone under vacuum; forming said heated polymer sheet material into a molded article in said forming zone.

28. 30. The heated polymer sheet material forming process of claim 27, wherein the heating zone comprises first and second heating elements on first and second sides, respectively, of the polymer sheet.

29. 30. The heated polymeric sheet material forming process of claim 27, further comprising maintaining a vacuum during and between said heating and transferring steps.

30. 30. The heated polymeric sheet material forming process of claim 27, wherein the formed article is a decorative automotive item.

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