Method of supporting a work piece

Abstract

During friction welding a disc ( 10 ) is mounted on a support member ( 16 ). A cavity ( 18 ) is defined between the support member ( 16 ) and an internal surface ( 9 ) of the disc ( 10 ). The cavity ( 18 ) is filled with a low melting point alloy. The low melting point alloy solidifies and expands to form a compressed layer that provides a load path from the disc ( 10 ) to the support member ( 16 ). The compressed layer has a thickness of the order of 3 mm and allows for tolerances in the disc ( 10 ) whilst offering the required level of support during the subsequent welding operation.

1 . A method of supporting a work piece during a welding operation comprising the steps of mounting a first work piece on a support member, the first work piece being mounted on the support member to define a cavity between an internal surface of the work piece and the support member, pouring a material into the cavity between the work piece and the support member, solidifying the material in the cavity, the solidifying material expanding to fill the cavity and form a compressed layer which stiffens the support members, welding at least one second work piece to an outer surface of the first work piece, the welding loads being transmitted through the compressed layer which acts to support the internal surface of the first work piece during the welding process, melting the compressed layer to release the welded work pieces from the support structure. 
   
   
       2 . A method as claimed in  claim 1  in which the material poured into the cavity is a low melting point alloy. 
   
   
       3 . A method as claimed in  claim 1  in which the material poured into the cavity is a low melting point alloy having a yield strength of the order of 40 MPa. 
   
   
       4 . A method as claimed in  claim 1  in which the thickness of the compressed layer is in the range of 1-10 mm. 
   
   
       5 . A method as claimed in  claim 1  in which the compressed layer has a thickness of the order of 3 mm. 
   
   
       6 . A method as claimed in  claim 1  in which the low melting point alloy has a volumetric expansion of the order of 0.5% upon solidification. 
   
   
       7 . A method as claimed in  claim 1  in which the support member is at least partially segmented. 
   
   
       8 . A method as claimed in  claim 1  in which the support member is made from a tool steel. 
   
   
       9 . A method as claimed in  claim 1  in which the first work piece is a disc and the second work piece is a blade. 
   
   
       10 . A method as claimed in  claim 1  in which the support member is segmented to support re-entrant features on the internal surface of the first work piece. 
   
   
       11 . A method as claimed in  claim 1  in which the welding process is a friction welding process.