Method of manufacturing a shell element provided with an undercut and a shell element manufactured by said method

Abstract

A method of manufacturing a shell element ( 13 ) for an electronic device, said shell element ( 13 ) having a front ( 5 ) and at least one part that is angled in relation to said front ( 5 ). The shell element ( 13 ) further comprises a formed sheet ( 6 ) that constitutes at least a part of the outer surface of said front ( 5 ) and at least a part of said part that is angled in relation to the front of the shell element ( 13 ). The method comprises the steps of first forming a sheet ( 1 ) to a desired shape including a part that is angled in relation to a front part ( 5 ) and then injection moulding a plastics material on the back of the formed sheet ( 6 ). At least one area of the angled part of the formed sheet ( 6 ) is provided with an undercut ( 7 ) at the latest during injection moulding of the plastics material on the back of the formed sheet ( 6 ). A shell element manufactured by this method is also disclosed.

1 . A method of manufacturing a shell element ( 13 ) for an electronic device, said shell element ( 13 ) having a front ( 5 ) and at least one part that is angled in relation to said front ( 5 ), said shell element ( 13 ) further comprising a formed sheet ( 6 ) that constitutes at least a part of the outer surface of said front ( 5 ) and at least a part of said part that is angled in relation to the front of the shell element ( 13 ), said method comprising the steps of: 
 forming a sheet ( 1 ) to a desired shape including a part that is angled in relation to a front part,    injection moulding a plastics material on the back of the formed sheet ( 6 ), characterised in    providing at least one area of the angled part of the formed sheet ( 6 ) with an undercut ( 7 ) at the latest during injection moulding of the plastics material on the back of the formed sheet ( 6 ).    
     
     
         2 . A method according to    claim 1   , characterised in trimming the edges of the formed sheet ( 6 ) before the plastics material is injection moulded on the back of the formed sheet ( 6 ).  
     
     
         3 . A method according to claims  1  or  2 , characterised in providing at least one opening ( 4 ) in the front part of the formed sheet ( 6 ) before the plastics material is injection moulded on the back of the formed sheet ( 6 ).  
     
     
         4 . A method according to any one of claims  1 - 3 , characterised in that the undercut ( 7 ) is provided during forming of the sheet ( 1 ) to the desired shape.  
     
     
         5 . A method according to    claim 4   , characterised in that the injection mould ( 9   a ,  9   b ) is provided with at least one protrusion ( 12 ) that extends into the at least one area provided with an undercut ( 7 ) when the formed sheet ( 6 ) is positioned in the injection mould ( 9   a ,  9   b ) for injection moulding a plastics material on the back of the formed sheet ( 6 ).  
     
     
         6 . A method according to claims  4  or  5 , characterised in that the injection mould ( 9   a ,  9   b ) is provided with at least one displaceable member ( 22 ) that is displaced into the at least one area provided with an undercut ( 7 ) when the formed sheet ( 6 ) is positioned in the injection mould ( 9   a ,  9   b ) for injection moulding a plastics material on the back of the formed sheet ( 6 ).  
     
     
         7 . A method according to any one of claims  1 - 3 , characterised in that the undercut ( 7 ) is provided in the formed sheet ( 6 ) by means of protrusions ( 12 ,  22 ) provided in the injection mould and under influence of an injection moulding pressure when the plastics material is injected into the injection mould ( 9   a ,  9   b ).  
     
     
         8 . A method according to any one of claims  1 - 7 , characterised in that the formed sheet ( 6 ) covers the entire front ( 5 ) of the shell element ( 13 ) and that the angled part comprises a circumferential flange ( 8 ) that extends from the front ( 5 ) of the shell element ( 13 ).  
     
     
         9 . A method according to any one of claims  1 - 8 , characterised in that the sheet ( 1 ) is a plastics material, such as polycarbonate (PC).  
     
     
         10 . A method according to any one of claims  1 - 9 , characterised in that the material that is injection moulded on the back of the formed sheet ( 6 ) is a plastics material, such as PC or ABS.  
     
     
         11 . A method according to any one of claims  1 - 10 , characterised in that the electronic device is a mobile radio station, such as a mobile telephone.  
     
     
         12 . A shell element ( 13 ) for an electronic device, said shell element ( 13 ) having a front ( 5 ) and at least one part that is angled in relation to said front ( 5 ), said shell element ( 13 ) comprising 
 a formed sheet ( 6 ) that constitutes at least a part of an outer surface of said front ( 5 ) and at least a part of said part that is angled in relation to the front ( 5 ) of the shell element ( 13 ),    a backing that is injection moulded on the back of the formed sheet ( 6 ), characterised in that at least one undercut ( 7 ) is provided in the part of the shell element ( 13 ) that is angled in relation to the front ( 5 ) of the shell element ( 13 ).    
     
     
         13 . A shell element according to    claim 12   , characterised in that the formed sheet ( 6 ) covers the entire front ( 5 ) of the shell element ( 13 ) and that the angled part comprises a circumferential flange ( 8 ) that extends from the front ( 5 ) of the shell element ( 13 ).  
     
     
         14 . A shell element according to    claim 12    or    13   , characterised in that at least one opening ( 4 ) is provided in the front ( 5 ) of the shell element ( 13 ).  
     
     
         15 . A shell element according to any one of claims  12 - 14 , characterised in that the sheet ( 1 ) is a plastics material, such as polycarbonate (PC).  
     
     
         16 . A shell element according to any one of claims  12 - 15 , characterised in that the material that is injection moulded on the back of the formed sheet ( 6 ) is a plastics material, such as PC or ABS.  
     
     
         17 . A shell element according to any one of claims  12 - 16 , characterised in that the electronic device is a mobile radio station, such as a mobile telephone.