Method of manufacturing a composite part comprising a core and at least one skin region

Abstract

A method of manufacturing a composite part comprising, a core ( 16 ) and at least one skin region ( 20, 22 ) formed of a skin polymer attached thereto, the skin polymer being a low-friction thermoplastic polymer, by: a) providing a mold with a heatable mold cavity; b) loading into the mold cavity a core element having a surface with at least one contacting region provided with a plurality of anchoring sites ( 10 ), and—previously or subsequently—loading into the mold cavity a layer of the skin polymer in powder form adjacent said contacting region and embedding the anchoring sites; c) applying a heat pressing step melting the skin polymer powder to form a molten skin polymer matrix ( 20, 22, 32 ); d) applying a cooling step, solidifying the skin polymer matrix forming a skin region mechanically engaged into anchoring sites of the core element forming the core.

1 . A method of manufacturing a composite part comprising a core ( 16 ) and at least one skin region ( 20 ,  22 ) formed of a skin polymer attached thereto, the skin polymer being a low-friction thermoplastic polymer, the method comprising the Mowing steps:
 a) providing a mold with a heatable mold cavity ( 4 ,  14 );   b) loading into the mold cavity a core element ( 6 ) having a surface with at least one contacting region provided with a plurality of anchoring sites ( 10 ,  28 ,  30 ,  34 ,  36 ), and—previously or subsequently—loading into the mold cavity a layer ( 2 ,  12 ) of the skin polymer in powder form adjacent said contacting region and embedding the anchoring sites;   c) applying a heat pressing step whereby the skin polymer powder is molten to form a molten skin polymer matrix ( 20 ,  22 ,  32 );   d) applying a cooling step, whereby the skin polymer matrix solidifies to form a skin region mechanically engaged into the anchoring sites of the core element forming the core.   
     
     
         2 . The method according to  claim 1 , wherein the skin polymer is ultra-high molecular weight polyethylene (UHMWPE). 
     
     
         3 . The method according to  claim 1 , wherein the layer of skin polymer powder is applied above and below the core element. 
     
     
         4 . The method according to  claim 1 , wherein the layer of skin polymer powder is applied patchwise. 
     
     
         5 . The method according to  claim 1 , wherein the core element is forted of a thermoplastic fleece ( 8 ) with reinforcement fibers ( 10 ), wherein the thermoplastic fleece consists of a core thermoplastic polymer, and wherein cavernous surface structures of the thermoplastic fleece and/or surface portions of the reinforcement fibers act as said anchoring sites, the heat pressing step causing melting of the core thermoplastic polymer, whereby the core element is formed to the core. 
     
     
         6 . The method according to  claim 5 , wherein the core thermoplastic polymer is polypropylene. 
     
     
         7 . The method according to  claim 5 , wherein the skin polymer is UHMWPE and the heat pressing step is carried out at a temperature of 190 to 230° C. with a pressure of 20 to 60 bar. 
     
     
         8 . The method according to  claim 5 , wherein the reinforcement fibers ( 10 ) are glass fibers. 
     
     
         9 . The method according to  claim 5 , wherein the core element ( 6 ) further comprises at least one reinforcement layer ( 24   a,    24   b ). 
     
     
         10 . The method according to  claim 9 , wherein the reinforcement layer is selected from a fabric, multiaxial stitch or unidirectional reinforcement. 
     
     
         11 . The method according to  claim 1 , wherein the core element ( 6 ) is formed as a solid or hollow body ( 36 ) and wherein the anchoring sites are configured as surface discontinuities such as recesses ( 30 ), rims or under-cuts ( 34 ). 
     
     
         12 . A composite part comprising a core ( 16 ) and at least one skin region ( 20 ,  22 ,  32 ) formed of a skin polymer attached thereto, the skin polymer being a low-friction thermoplastic polymer, the core element having a surface with at least one contacting region provided with a plurality of anchoring sites ( 10 ,  28 ,  30 ,  34 ,  36 ), and the skin region being mechanically engaged into the anchoring sites of the core element, the skin region having a thickness of 0.5 to 10 mm. 
     
     
         13 . The composite pan according to  claim 11 , wherein the skin polymer is UHMWPE. 
     
     
         14 . The composite part according to  claim 12 , wherein the core comprises a solid matrix ( 18 ) of the core thermoplastic and reinforcement fibers ( 10 ), which together form anchoring sites embedded by the skin polymer ( 22 ). 
     
     
         15 . The composite part according to  claim 14 , wherein the core thermoplastic is polypropylene