Method and apparatus for performing a magnetic pulse forming process

Abstract

A magnetic pulse forming process is performed by an apparatus and a method that causes the plasticity of a workpiece to be preliminarily increased to facilitate deformation to the desired shape. Initially, a mandrel having a surface and an electrically conductive member are provided. The workpiece is oriented between the surface of the mandrel and the electrically conductive member, and a first electrical current is caused to flow through the workpiece and the electrically conductive member so as to increase the plasticity of the workpiece. Then, a second electrical current is caused to flow through the electrically conductive member and the workpiece so as to cause to cause the workpiece to be deformed into engagement with the surface of the mandrel.

1 . A method of deforming a workpiece comprising the steps of: 
 (a) providing a mandrel having a surface;    (b) providing an electrically conductive member;    (c) orienting a workpiece between the surface of the mandrel and the electrically conductive member;    (d) causing a first electrical current to flow through the workpiece and the electrically conductive member so as to increase the plasticity of the workpiece; and    (e) causing a second electrical current to flow through the electrically conductive member and the workpiece so as to cause to cause the workpiece to be deformed into engagement with the surface of the mandrel.    
     
     
         2 . The method defined in  claim 1  wherein said step (a) is performed by providing the mandrel having an outer surface, said step (b) is performed by providing the electrically conductive member having an inner surface, and said step (c) is performed by orienting the workpiece between the outer surface of the mandrel and the inner surface of the electrically conductive member.  
     
     
         3 . The method defined in  claim 1  wherein said step (a) is performed by providing the mandrel having an inner surface, said step (b) is performed by providing the electrically conductive member having an outer surface, and said step (c) is performed by orienting the workpiece between the inner surface of the mandrel and the outer surface of the electrically conductive member.  
     
     
         4 . The method defined in  claim 1  wherein said step (c) is performed by connecting a preheating current source so as to cause a first electrical current to flow through the workpiece and the electrically conductive member.  
     
     
         5 . The method defined in  claim 4  wherein said step (c) is performed by connecting the preheating current source through an electrically conductive end member and a first electrically conductive insert to a first portion of the workpiece and by connecting a second portion of the workpiece through a second electrically conductive insert to the preheating current source.  
     
     
         6 . The method defined in  claim 1  wherein said step (d) is performed by connecting a pulse current source so as to cause a first electrical current to flow through the workpiece and the electrically conductive member.  
     
     
         7 . The method defined in  claim 6  wherein said step (d) is performed by connecting the pulse current source through an electrically conductive end member and a first electrically conductive insert to a first portion of the workpiece and by connecting a second portion of the workpiece through a second electrically conductive insert to the pulse current source.  
     
     
         8 . The method defined in  claim 1  wherein said step (c) is performed by connecting a preheating current source so as to cause a first electrical current to flow through the workpiece and the electrically conductive member, and wherein said step (d) is performed by connecting a pulse current source so as to cause a first electrical current to flow through the workpiece and the electrically conductive member.  
     
     
         9 . The method defined in  claim 8  wherein said step (c) is performed by connecting the preheating current source through an electrically conductive end member and a first electrically conductive insert to a first portion of the workpiece and by connecting a second portion of the workpiece through a second electrically conductive insert to the preheating current source.  
     
     
         10 . The method defined in  claim 9  wherein said step (d) is performed by connecting the pulse current source through the electrically conductive end member and the first electrically conductive insert to the first portion of the workpiece and by connecting the second portion of the workpiece through the second electrically conductive insert to the pulse current source.  
     
     
         11 . The method defined in  claim 1  wherein said step (b) is performed by providing a magnetic field concentrator adjacent to the electrically conductive member, and wherein said step (c) is performed by orienting the workpiece between the surface of the mandrel and the magnetic field concentrator.  
     
     
         12 . The method defined in  claim 1  wherein said step (c) is performed by orienting first and second workpieces between the surface of the mandrel and the electrically conductive member, said step (d) is performed by causing a first electrical current to flow through the first and second workpieces and the electrically conductive member so as to increase the plasticity of the first and second workpieces, and said step (e) is performed by causing a second electrical current to flow through the electrically conductive member and the first and second workpieces so as to cause to cause the first and second workpieces to be deformed into engagement with the surface of the mandrel.  
     
     
         13 . The method defined in  claim 1  wherein said step (a) is performed by providing a mandrel having a surface and a recess, and wherein said step (e) is performed by causing the workpiece to be deformed into engagement with the surface and the recess of the mandrel.  
     
     
         14 . An apparatus for deforming a workpiece comprising: 
 a mandrel having a surface;    an electrically conductive member positioned relative to said mandrel such that a workpiece can be oriented between said surface of said mandrel and said electrically conductive member;    means for causing a first electrical current to flow through the workpiece and the electrically conductive member so as to increase the plasticity of the workpiece; and    means for causing a second electrical current to flow through the electrically conductive member and the workpiece so as to cause to cause the workpiece to be deformed into engagement with the surface of the mandrel.    
     
     
         15 . The apparatus defined in  claim 14  wherein said means for causing a first electrical current to flow includes a preheating current source connected through an electrically conductive end member to a first electrically conductive insert that is adapted to engage the workpiece.  
     
     
         16 . The apparatus defined in  claim 14  wherein said means for causing a second electrical current to flow includes a pulse current source connected through an electrically conductive end member to a first electrically conductive insert that is adapted to engage the workpiece.  
     
     
         17 . The apparatus defined in  claim 14  wherein said means for causing a first electrical current to flow includes a preheating current source connected through an electrically conductive end member to a first electrically conductive insert that is adapted to engage the workpiece, and wherein said means for causing a second electrical current to flow includes a pulse current source connected through said electrically conductive end member to said first electrically conductive insert that is adapted to engage the workpiece.