Expanded compression molding of composite plastics
View Patent ↗Composite polymeric articles significantly larger than the size of a compression molding press are produced by providing a plurality of expandable pillows interposed between an upper plate and the upper exterior surface of an outside the press upper mold. The upper plate has a plurality of downwardly extending paired vertical arms attached to opposite sides of the upper plate. Each vertical arm has a lower portion having a eyelet (or aperture), and each pair of vertical arms together forms an aligned pair of eyelets. When the upper and lower mold portions are pressed together, the eyelets reside below the exterior lower surface of the outside the press lower mold portion. Each eyelet is dimensioned to reversibly receive a horizontal or lateral arm that is deployed below the exterior lower surface of the outside the press lower mold portion. A plastic material is introduced onto the interior surface of the lower mold portion, which is compressed between the upper and lower mold portions via a press having a press area that does not extend out over the outside the press portions of the upper and lower mold portions. The lateral arms are extended through the paired and aligned eyelets. The plurality of expandable pillows are expanded, and the lateral arms are brought into compressive abutment with the exterior lower surface of the outside the press lower mold portion. The plastic material residing between the outside the press upper mold portion and the outside the press lower mold portion is then correspondingly compressed.
1. A method of forming a molded article comprising:
a. providing a mold apparatus comprising;
i. a upper mold portion having an exterior pressable surface and an interior surface;
ii. a lower mold portion having an exterior pressable surface and an interior surface;
iii. a press having a press surface, a portion of said upper mold portion extending beyond said press surface and having an outside the press upper mold portion exterior surface and an outside the press upper mold portion interior surface, a portion of said lower mold portion extending beyond said press surface and having an outside the press lower mold portion exterior surface and an outside the press lower mold portion interior surface;
iv. said press being positioned to reversibly position said interior surface of said upper mold portion and said interior surface of said lower mold portion towards each other;
v. said outside the press upper mold portion interior surface and said outside the press lower mold portion interior surface together defining an outside the press internal mold space, when said upper mold portion and said lower mold portion are pressed together;
vi. a plate having a first surface and a second surface, said second surface of said plate being opposed to said outside the press upper mold portion exterior surface, said plate being separate from said press;
vii. at least one expandable member interposed between said second surface of said plate and said outside the press upper mold portion exterior surface;
viii. a plurality of vertical arms attached to opposite sides of said plate and forming a plurality of oppositely paired vertical arms, each vertical arm extending towards said lower mold portion, each vertical arm having a terminal portion having a guide, each pair of oppositely paired vertical arms together forming an aligned pair of guides, each aligned pair of guides being dimensioned to receive reversibly a lateral arm there-through;
b. introducing a polymeric material onto said interior surface of said lower mold portion;
c. pressing said upper mold portion and said lower mold portion together by means of said press, and compressing said plastic material between said interior surface of said upper mold portion and said interior surface of said lower mold portion, said guide of each vertical arm concurrently being positioned beyond said outside the press lower mold portion exterior surface;
d. inserting said lateral arm through each aligned pair of guides;
e. expanding each expandable member resulting in said plate moving away from said outside the press upper mold portion exterior surface and each lateral arm being brought into compressive contact with said outside the press lower mold portion exterior surface, and correspondingly compressing further said plastic material residing within said outside the press internal mold space, thereby forming said molded article.
2. The method of claim 1 wherein each expandable member is an expandable pillow interposed between said second surface of said plate and said outside the press upper mold portion exterior surface.
3. The method of claim 1 wherein each expandable member is an expandable tube interposed between said second surface of said plate and said outside the press upper mold portion exterior surface.
4. The method of claim 1 wherein,
a. a portion of said upper mold portion resides in alignment within said press surface and has an intra-press upper mold portion exterior surface and an intra-press upper mold portion interior surface, a portion of said lower mold portion resides in alignment within said press surface and has an intra-press lower mold portion exterior surface and an intra-press lower mold portion interior surface;
b. said intra-press upper mold portion interior surface and said intra-press lower mold portion interior surface together defining an intra-press internal mold space, when said upper mold portion and said lower mold portion are pressed together;
c. further wherein plastic material residing within said intra-press internal mold space is submitted to a compressive intra-press pressure, when said upper mold portion and said lower mold portion are pressed together;
d. plastic material residing within said outside the press internal mold space is submitted to a compressive outside the press pressure, when said upper mold portion and said lower mold portion are pressed together;
e. said compressive intra-press pressure and said compressive outside the press pressure being substantially equivalent.
5. The method of claim 1 , wherein said polymeric material is a thermoplastic plastic.
6. The method of claim 1 , wherein said polymeric material is a thermoset plastic.
7. The method according to claim 1 , further comprising controlling the flow of polymeric material to vary the quantity of molten polymeric material being delivered to the lower portion of the mold.
8. The method according to claim 1 , wherein the molten polymeric material is blended with the fibers being between approximately at least 12 millimeters and approximately 100 millimeters in length to form a molten composite polymeric material.
9. The method according to claim 8 , wherein said blending forms a molten composite polymeric material having a concentration of fiber of approximately at least ten percent by weight.
10. The method according to claim 8 , further comprising varying the volumetric flow rate of the molten composite polymeric material being gravitated onto the lower mold.
11. The method according to claim 8 , wherein a first layer of molten composite polymeric material is extruded into the lower portion of the mold.
12. The method according to claim 11 , wherein a second layer of molten composite polymeric material is layered on top of the first layer.
13. A molding system for forming extended articles larger than the press area of a press from polymeric material and reinforcing material, said molding system comprising:
a. an upper mold portion having an exterior pressable surface and an interior surface;
b. a lower mold portion having an exterior pressable surface and an interior surface;
c. a press having a press surface, a portion of said upper mold portion extending beyond said press surface and having an outside the press upper mold portion exterior surface and an outside the press upper mold portion interior surface, a portion of said lower mold portion extending beyond said press surface and having an outside the press lower mold portion exterior surface and an outside the press lower mold portion interior surface;
d. said press being positioned to reversibly position said interior surface of said upper mold portion and said interior surface of said lower mold portion towards each other;
e. said outside the press upper mold portion interior surface and said outside the press lower mold portion interior surface together defining an outside the press internal mold space, when said upper mold portion and said lower mold portion are pressed together;
f. a plate having a first surface and a second surface, said second surface of said plate being opposed to said outside the press upper mold portion exterior surface, said plate being separate from said press;
g. at least one expandable member interposed between said second surface of said plate and said outside the press upper mold portion exterior surface;
h. a plurality of vertical arms attached to opposite sides of said plate and forming a plurality of oppositely paired vertical arms, each vertical arm extending towards said lower mold portion, each vertical arm having a terminal portion having a guide, each pair of oppositely paired vertical arms together forming an aligned pair of guides, each aligned pair of guides being dimensioned to receive reversibly a lateral arm there-through.
14. The system of claim 13 , further comprising a deposition tool, said injection unit barrel and said deposition tool operable to control the flow of composite polymeric material in a varied amount of molten composite polymeric material being delivered to the lower portion of the mold.
15. The system of claim 13 , wherein said injection unit barrel is an injection head.
16. The system of claim 15 , wherein said injection head includes an screw having a thread spacing large enough to blend the molten polymeric material with the fibers being between approximately 12 millimeters and approximately 100 millimeters in length.
17. The system of claim 13 , wherein said injection unit barrel is an extruder.
18. The system of claim 13 , wherein said deposition tool is an injection nozzle.
19. The system of claim 13 , wherein said deposition tool is an injection die.
20. The system of claim 13 wherein said deposition tool is a dynamic die.
21. The system according to claim 13 , wherein the blended molten composite polymeric material has a concentration of fiber of at least approximately ten percent by weight.
22. The system according to claim 13 , further comprising a controller coupled to said first trolley and operable to move said first trolley to position the lower mold to form a predetermined quantity of molten composite material of varying thickness on the mold.
23. The according to claim 13 , wherein said first trolley includes wheels operable to move the first trolley.
24. The system according to claim 13 , further comprising a controller coupled to said injection unit barrel and operable to vary the volumetric flow rate of the molten polymeric composite material and gravitate the molten composite polymeric material onto the lower mold.
25. The system of claim 24 , wherein said controller moves said first trolley directly below said injection unit barrel for gravitating the extruded composite polymeric material onto the lower mold.
26. The system of claim 13 , wherein said polymeric material is a thermoplastic plastic.
27. The system of claim 13 , wherein said polymeric material is a thermoset plastic.
28. The system of claim 13 , wherein each expandable member is an expandable pillow interposed between said second surface of said plate and said outside the press upper mold portion exterior surface.
29. The system of claim 13 , wherein each expandable member is an expandable tube interposed between said second surface of said plate and said outside the press upper mold portion exterior surface.