Device and method for the axial forming of elongated hollow bodies

Abstract

A device and a method for axially forming an elongated hollow body is disclosed. The device has at least one receptacle, a reducing die, a punch for pressing the elongated hollow body through the reducing die in the direction of an axis, an expanding mandrel and means for limiting the axial displacement of the punch. The punch and the expanding mandrel are movable on the same axis and the expanding mandrel is arranged inside the punch. The hollow body is reduced to a first diameter in a first portion and expanded to a second diameter in a second portion as a result of a movement of the punch and the expanding mandrel in the same direction.

1 . A device for axial forming of an elongate hollow body, comprising:
 a reduction die for leading through the elongate hollow body,   a ram for pushing the elongate hollow body through the reduction die in the direction of an axis,   an expansion mandrel, and   a mechanism that limits the axial movement of the ram, wherein the ram and the expansion mandrel are movable on the same axis and the expansion mandrel is arranged within the ram.   
   
   
       2 . The device as claimed in  claim 1 , wherein the expansion mandrel is movable independently of the ram. 
   
   
       3 . A method for axial forming of an elongate hollow body, comprising:
 moving a ram and an expansion mandrel in the same direction such that the elongate hollow body is reduced to a first diameter in a first portion during a first process, and is expanded in a second portion to a second diameter during a second process.   
   
   
       4 . The method as claimed in  claim 3 , in which during the first process, a parallel movement of the ram and of the expansion mandrel takes place within a receptacle for positioning the elongate hollow body, wherein the ram pushes the elongate hollow body into a reduction die. 
   
   
       5 . The method as claimed in  claim 3 , in which the processes of the expansion and of the reduction of the first and second portions of the hollow body are carried out in direct succession. 
   
   
       6 . The method as claimed in  claim 3 , in which during the second process, only an axial movement of the expansion mandrel is carried out until the expansion mandrel extends at least partially into a reduction die. 
   
   
       7 . The method as claimed in  claim 3 , in which the ram acts on the elongate hollow body axially and the expansion mandrel acts on the elongate hollow body radially from the inside. 
   
   
       8 . (canceled) 
   
   
       9 . The device as claimed in  claim 1 , wherein the device further comprises a heating element operatively connected thereto. 
   
   
       10 . The device as claimed in  claim 9 , wherein the heating element is operatively connected to at least one of the reduction die, ram and expansion mandrel. 
   
   
       11 . The device as claimed in  claim 1 , wherein the device further comprises a receptacle for receiving the hollow body, the receptacle defined by an engagement opening that is configured to receive the ram and expansion mandrel. 
   
   
       12 . The device as claimed in  claim 11 , wherein the reduction die is positioned at an end of the receptacle, opposite the engagement opening. 
   
   
       13 . The device as claimed in  claim 1 , wherein the reduction die is defined by a first opening having a first diameter, a tapered portion, and a second opening defined by a second diameter. 
   
   
       14 . The device as claimed in  claim 1 , wherein the mechanism is a feed motion limiter. 
   
   
       15 . The device as claimed in  claim 1 , wherein the reduction die is selectively removable from the device so as to release the hollow body from the device. 
   
   
       16 . The method as claimed in  claim 4 , further comprising heating the receptacle. 
   
   
       17 . The method as claimed in  claim 6 , further comprising heating the reduction die. 
   
   
       18 . The method as claimed in  claim 3 , further comprising heating at least one of the ram and the expansion mandrel. 
   
   
       19 . The method as claimed in  claim 4 , further comprising heating the hollow body prior to placing the hollow body within the receptacle. 
   
   
       20 . The method as claimed in  claim 4 , further comprising selectively separating the reduction die from the receptacle after the second process to release the hollow body.