Thermoplastic molding process and apparatus
View Patent ↗A system and method for forming an article from thermoplastic material and fiber. The method includes heating thermoplastic material to form a molten thermoplastic material for blending with the fiber. The molten thermoplastic material is blended with the fibers to form a molten composite material having a concentration of fiber by weight. The molten composite material may then be extruded through dynamic dies to deliver discrete controlled material that is gravitated onto a lower portion of a mold. The lower portion of the mold may be moved in space and time while receiving the flow of composite material to deposit a predetermined quantity of molten composite material thereon conforming to mold cavities of the lower and an upper portion of the mold. The upper portion of the mold may be pressed against the predetermined quantity of molten composite material and closing on the lower portion of the mold to form the article.
1. A method for forming a solid article from a viscous material and fiber, said method comprising:
blending the viscous material with the fiber to form a composite material;
extruding the composite material and depositing gravitationally said composite material onto a lower mold portion;
moving at least a portion of the lower mold portion during gravitational depositing of the composite material, so as to deposit a quantity of composite material on said lower mold portion conforming to mold cavities of the lower mold portion;
compressing an upper mold portion against said quantity of composite material, after said quantity of composite material has been gravitationally deposited onto said lower mold portion; and
maintaining the quantity of composite material under such conditions that the quantity of composite material hardens within a mold cavity formed between the upper mold portion and the lower mold portion, so as to form said solid article.
2. The method of claim 1 , further comprising controlling flow of composite material to vary the quantity of composite material being gravitationally deposited onto the lower mold portion over time.
3. The method of claim 1 , wherein the fiber blended with the viscous material is between approximately one-half and approximately four inches in length.
4. The method of claim 1 , wherein the fiber has an average fiber length of at least one inch.
5. The method of claim 1 , wherein said composite material comprises a concentration of fiber of approximately at least ten percent by weight.
6. The method of claim 1 , wherein the composite material comprises a concentration of fiber of at least 40 percent by weight.
7. The method of claim 1 , wherein moving of the lower mold portion, results in formation of a predetermined quantity of composite material of varying thickness on said lower mold portion.
8. The method of claim 1 , wherein moving of the lower mold portion is along a single axis.
9. The method of claim 1 , wherein extruding said composite material produces composite material having a minimum of approximately 85 percent of unbroken fibers.
10. The method of claim 1 , further comprising the step of controlling said extruding to vary a volumetric flow rate and a relative position of an extrusion die and the lower mold portion.
11. The method of claim 1 , wherein the composite material is extruded onto an insert contained within the lower mold portion.
12. The method of claim 11 , wherein the insert is at least partially embedded within the composite material.
13. The method of claim 1 , wherein, extruding comprises extruding at least one first layer and at least one second layer onto the lower mold portion.
14. The method of claim 1 , wherein said viscous material comprises a thermoplastic resin.
15. The method of claim 1 , wherein said viscous material comprises a thermoset resin.
16. The method of claim 1 , wherein said maintaining step comprises causing a chemical reaction within the mold cavity.
17. The method of claim 1 , wherein the viscous material comprises at least one polymer selected from the group consisting of: polyethylene; polysulfone; polypropylene oxide; polyvinyl chloride; polybutylene terephthalate; polyvinylidene chloride; polyethylene terephthalate; polystyrene; polycyclohexane diethylene; terephthalate; styrene-butadiene-acrylonitrile; polybutylene naphthalate copolymer; nylon 6; nylon 66; nylon 11; nylon 12; thermotropic liquid crystal polymers; polyphenylene sulfide; polyether ether ketones; polyether sulfones; copolymers of aliphatic nylons polyether imides further copolymerized with terephthalic acid or other aromatic dicarboxylic acids or aromatic diamines; polyamide imides; copolymerized polyamides polyimides; polycarbonate; polyurethane; polyacetal; polyether amides; polymethylmethacrylate; and polyester amides.
18. The method of claim 1 , wherein extruding comprises dynamically outputting the composite material at different volumetric flow rates across a plane; and
positionally synchronizing said lower mold portion to receive the composite material in relation to the different volumetric flow rates across the plane.
19. The method of claim 1 wherein said lower mold portion resides on a trolley, and said upper mold portion resides within a press, said method further comprising,
transporting said lower mold portion on said trolley into said press, after depositing gravitationally said composite material onto said lower mold portion, and
compressing, within said press, said upper mold portion against said quantity of composite material, after said quantity of composite material has been gravitationally deposited onto said lower mold portion.