Reinforced thermoplastic molding technique method
AssigneeThe Budd Company
InventorBruce Norman Greve
Life of this patent
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Abstract
A method and apparatus for binding the fibers of, and forming a fiber reinforced plastic structure. A fiber reinforced plastic preform is created by depositing a mixture of reinforcing fibers, binding fibers and resin matrix fibers on a screen having a preselected geometry. The fiber reinforced plastic preform is exposed to high temperature fluid causing the binding fibers to melt and, thereafter, to cool air to temporarily bind the preform in a tackified state. The tackified preform is exposed to a higher temperature fluid causing the resin matrix fibers to melt and, thereafter, to cool air to solidify and thus bind and lock the reinforcing fibers of the tackified preform in place to create a homogeneous fiber reinforced plastic structure.
Claims11
A method for forming a fiber reinforced plastic structure which comprises:
- (a) creating a one-piece preform haying three-dimensional contours approximating a desired shape for the structure, said preform being made from a mixture having reinforcing fibers and thermoplastic meltable resin matrix fibers;
- (b) placing the preform into a complementary shaped mold;
- (c) heating the preform to a temperature sufficient to melt the resin matrix fibers into a resin which flows to surround the reinforcing fibers without substantial displacement of the reinforcing fibers;
- (d) cooling the preform to solidify the resin matrix fibers and form a rigid fiber reinforced plastic structure having an essentially uniform distribution of the reinforcing fibers therein bound together by the resin of the resin matrix fibers without introducing additional resin into the preform;
- (e) wherein the mixture includes a sufficient concentration of the resin matrix fibers to yield a substantially homogenous fiber reinforced plastic structure and a sufficient concentration of the reinforcing fibers to provide structural rigidity to the fiber reinforced plastic structure;
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- (f) removing the rigid fiber reinforced plastic structure from the mold.
Method for forming a fiber reinforced plastic structure which comprises:
- a) placing a contoured screen in a tank filled with liquid;
- b) adding reinforcing fibers to the liquid to create a slurry wherein a length of the reinforcing fibers ranges from 0.5 to 6 inches;
- c) adding meltable resin matrix thermoplastic fibers to the slurry wherein a length of the resin matrix fibers ranges from 0.5 to 3 inches;
- d) adding meltable binding thermoplastic fibers to the slurry, wherein a length of the binding fibers ranges from 0.25 to 1.25 inches, the binding fibers have a lower melting point and a lower concentration than the meltable resin matrix thermoplastic fibers, the binding fibers comprising approximately 2-7 percent by weight of a total weight of a preform and having a melting temperature of less than about 270.degree. F., and wherein the resin matrix fibers comprise approximately 30-70 percent by weight of the total weight of the preform and having a melting temperature of between about 300.degree. F. and about 450.degree. F.;
- e) raising the screen in the tank thereby causing the fibers to be deposited on the screen to form a one piece preform having three dimensional contours approximating a desired shape for the structure;
- f) removing the screen from the tank;
- g) heating the preform to a temperature above the melting point of the binding fibers but below the melting point of the resin matrix fibers to yield a tackified preform;
- h) removing the tackified preform from the screen;
- i) placing the tackified preform in a mold, the mold having a pair of complimentary dies, each having contoured molding surfaces defining a three dimensional cavity, such that the three dimensional contours of the preform generally conform to the molding surfaces of the dies;
- j) heating the tackified preform to a temperature above about 300.degree. F. and sufficient to melt the meltable resin matrix fibers such that the meltable resin matrix fibers melt into a resin which flows throughout the tackified preform without substantial displacement of the reinforcing fibers to yield a fiber reinforced plastic structure having an essentially uniform distribution of the reinforcing fibers therein bound together by at least the resin provided by the resin matrix fibers thereby eliminating a need for introducing additional resin into the preform;
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- k) removing the fiber reinforced plastic structure from the three dimensional cavity of the mold.
Dependencies are inferred from the claim text.