Method for molding and impact resistant automotive part produced thereby

Abstract

A molding method and an impact resistant automotive part such as a bumper beam resulting from the molding method are obtained wherein a thermoplastic reinforced fiber structure at least partially forms a pair of attachment portions of the part and continuously extends between the attachment portions to link the attachment portions. The method includes the steps of providing a plurality of blanks, heating the plurality of blanks, and stacking the plurality of blanks to form a stack of blanks. The stack is then stamped to form the part including the pair of attachment portions spaced a predetermined distance apart. The thermoplastic reinforced fiber structure has tows of fibers wetted by a resin material such as polypropylene. Preferably, the fibers are woven glass fibers.

What is claimed is:  
     
         1 . A method for molding an impact resistant automotive part adapted to be attached to an automotive vehicle at a pair of attachment locations spaced a predetermined distance apart, the method comprising the steps of: 
 providing a plurality of blanks of material including at least one layer having tows of fibers;    heating the plurality of blanks;    stacking the plurality of blanks to form a stack of blanks; and    stamping the stack to form an automotive part having a pair of attachment portions spaced the predetermined distance apart wherein the tows of fibers are wetted by a resin material to form at least one thermoplastic reinforced fiber structure which at least partially forms the pair of attachment portions and continuously extends between the attachment portions to link the attachment portions.    
     
     
         2 . The method as claimed in  claim 1  wherein the resin material is polypropylene.  
     
     
         3 . The method as claimed in  claim 1  wherein the tows are woven.  
     
     
         4 . The method as claimed in  claim 1  wherein the attachment portions have inner and outer surfaces and wherein two thermoplastic reinforced fiber structures at least partially form the attachment portions at the inner and outer surfaces.  
     
     
         5 . The method as claimed in  claim 4  wherein each of the two thermoplastic reinforced fiber structures is formed from a single-layer blank.  
     
     
         6 . The method as claimed in  claim 4  wherein each of the two thermoplastic reinforced fiber structures is formed from a multi-layer blank.  
     
     
         7 . The method as claimed in  claim 1  wherein the tows are aligned to improve part stiffness.  
     
     
         8 . The method as claimed in  claim 1  wherein the tows are unidirectional and wherein the unidirectional tows are attached together to preserve tow alignment during molding.  
     
     
         9 . The method as claimed in  claim 3  wherein the woven fibers are unbalanced.  
     
     
         10 . The method as claimed in  claim 1  wherein each of the attachment portions is cone-shaped.  
     
     
         11 . The method as claimed in  claim 1  wherein the plurality of blanks include a plurality of blanks of glass mat thermoplastics.  
     
     
         12 . The method as claimed in  claim 1  wherein at least one of the blanks includes a glass mat layer and at least one layer of thermoplastic material.  
     
     
         13 . The method as claimed in  claim 1  wherein the fibers are glass fibers.  
     
     
         14 . An automotive part molded from a plurality of blanks and adapted to be attached to an automotive vehicle at a pair of attachment locations spaced a predetermined distance apart, the part comprising: 
 a central shock-absorbing portion;    a pair of attachment portions connected to the central shock-absorbing portion and spaced the predetermined distance apart; and    at least one thermoplastic reinforced fiber structure which at least partially forms the central shock-absorbing portion and the pair of attachment portions and continuously extends between the attachment portions to link the attachment portions.    
     
     
         15 . The part as claimed in  claim 14  wherein the thermoplastic material is polypropylene.  
     
     
         16 . The part as claimed in  claim 14  wherein the tows are woven.  
     
     
         17 . The part as claimed in  claim 14  wherein the attachment portions have inner and outer surfaces and wherein two spaced apart thermoplastic reinforced fiber structures at least partially form the attachment portions at the inner and outer surfaces.  
     
     
         18 . The part as claimed in  claim 17  wherein each of the two spaced apart thermoplastic reinforced fiber structures is formed from a single-layer blank.  
     
     
         19 . The part as claimed in  claim 17  wherein each of the spaced apart thermoplastic reinforced fiber structures is formed from a multi-layer blank.  
     
     
         20 . The part as claimed in  claim 14  wherein the tows are aligned to improve part stiffness.  
     
     
         21 . The part as claimed in  claim 14  wherein the tows are unidirectional and wherein the unidirectional tows are attached together to preserve tow alignment during molding.  
     
     
         22 . The part as claimed in  claim 16  wherein the woven fibers are unbalanced.  
     
     
         23 . The part as claimed in  claim 14  wherein each of the attachment portions is cone-shaped.  
     
     
         24 . The part as claimed in  claim 14  wherein the plurality of blanks include a plurality of blanks made of glass mat thermoplastics.  
     
     
         25 . The part as claimed in  claim 14  wherein at least one of the blanks includes a glass mat layer and at least one layer of thermoplastic material.  
     
     
         26 . The part as claimed in  claim 14  wherein the fibers are glass fibers.