Method and device for the production of a tubular workpiece, particularly a shock absorber piston rod, and such a workpiece

Abstract

The invention describes a method for producing a tubular workpiece, especially a shock-absorber piston rod, wherein, starting out from a tubular initial workpiece ( 3 ), a first area ( 3 a ) of the initial workpiece ( 3 ) is reduced in a first step by a radial forming process for reducing its outer diameter, and a transition area ( 3 c ), extending at an angle relative to the longitudinal axis (A) of the tubular initial workpiece ( 3 ), is formed, said transition area ( 3 c ) extending between said first area ( 3 a ) of the initial workpiece ( 3 ) having the reduced diameter and a non-reduced second area ( 3 b ) following the transition area ( 3 c ), characterized in that in a second process step, following the first process step. It is provided according to the transition area ( 3 c ) of the initial workpiece ( 3 ) is cold-formed to obtain the substantially rectangular shoulder ( 2 ) of the workpiece ( 1 ).

1 . Method for producing a tublar workpiece, comprising: 
 first processing steps of: 
 reducing a first area of the initial workpiece by a radial forming process for reducing the outer diameter of the workpiece,  
 forming a transition area, extending at an angle relative to the longitudinal axis of the tubular initial workpiece said transition area extending between said first area of the initial workpiece having the reduced diameter and a non-reduced second area following the transition area  
   a second process step of: 
 cold forming the transition area of the initial workpiece is cold to obtain a substantially rectangular shoulder of the workpiece.  
   
   
   
       2 . The method as defined in  claim 11 , wherein the orbital forming process of the second process step is an orbital forging or axial pressing process.  
   
   
       3 . The method as defined in  claim 2 , wherein the orbital forging process is effected by at least one of circular movement and a tilting movement.  
   
   
       4 . Workpiece with a substantially rectangular shoulder comprising: 
 an intial workpiece haing a wall and a shoulder wherein the shoulder is an integral part of the wall of the initial workpiece and the shoulder is produced by cold forming the initial workpiece by a radial forming process, followed by an orbital forging or axial pressing process.    
   
   
       5 . Device for producing a tubular workpiece with a substantially rectangular shoulder comprising: 
 a reducing unit, adapted to form a transistion area in the form of a circumferential inclined surface can be formed in a tubular initial workpiece, and    a forming unit adapted to convert the inclined transition area to a substantially rectangular shoulder of the workpiece by cold forming of the intial workpiece.    
   
   
       6 . The device as claimed in  claim 5 , wherein the reducing unit of the device comprises at least one forging die.  
   
   
       7 . The device as claimed in  claim 6 , wherein the at least one forging die comprises an inclined forming surface.  
   
   
       8 . The device as claimed in  claim 5 , wherein the forming unit of the device is designed as an orbital forming unit.  
   
   
       9 . The device as claimed in  claim 5 , wherein the forming unit comprises an orbital tool that performs an orbital movement about a longitudinal axis of the initial workpiece.  
   
   
       10 . The method as defined in  claim 1 , wherein radial forming of the first area is effected by rotary swaging.  
   
   
       11 . The method as defined in  claim 1 , wherein the cold-forming process of the second process step is an orbital forming process.