Method and Device for Producing a Peripherally Closed Hollow Profile

Abstract

In a method and apparatus for producing a peripherally closed hollow profile having a secondary feature and/or a branch, the hollow profile is shaped from a hollow profile blank by an internal high pressure. The cap of the secondary feature and/or of the branch is severed by a counterholding punch that supports the secondary feature or the branch during the shaping process. In order to permit the production of a hollow profile having secondary features and/or branches, during which the cap of the secondary feature or of the branch is severed in a simple and reliable manner in terms of the process, the cap of the secondary feature and/or of the branch is severed at an internal high pressure which corresponds at most to the forming pressure for forming the hollow profile from the blank.

1 - 7 . (canceled)  
     
     
         8 . A method of producing a peripherally closed hollow profile having a secondary feature or a branch, said method comprising: 
 shaping a hollow profile from a hollow profile blank by applying an internal high pressure whereby said hollow profile blank undergoes an expansion; and    severing a cap of the secondary feature or of the branch by a counterholding punch which supports the secondary feature or the branch during the act of shaping;    wherein the cap of the secondary feature or of the branch is severed at an internal high pressure which corresponds at most to a forming pressure for forming the hollow profile from the hollow profile blank, by a stroke of the counterholding punch in an opposite direction to an expansion direction of the hollow profile.    
     
     
         9 . The method as claimed in  claim 8 , wherein, after the act of severing by a plunging movement of the counterholding punch into the secondary feature or the branch, the secondary feature or the branch is calibrated by a calibrating contour corresponding to a shape of the secondary feature or of the branch.  
     
     
         10 . A device for producing a peripherally closed hollow profile having a secondary feature or a branch, comprising: 
 a hydroforming tool for shaping the hollow profile; and    a counterholding punch which is integrated in the hydroforming tool in a displaceable manner and supports the secondary feature or the branch during a shaping process; wherein    the counterholding punch is driven so that, after the shaping of the secondary feature or of the branch, the counterholding punch plunges into said secondary feature or said branch and severs a cap of the secondary feature or of the branch by a severing contour;    an end face of the counterholding punch runs in a continuously even manner;    an end edge of the counterholding punch forms the severing contour;    a passage is formed in the forming tool in which the counterholding punch is guided in a displaceable manner; and    the width of an annual gap between a wall of said passage and a punch circumference corresponds approximately to a wall thickness of the secondary feature or of the branch.    
     
     
         11 . The device as claimed in  claim 10 , wherein a punch end which contains the severing contour is of frustoconical design and has bevel surfaces facing the secondary feature or the branch.  
     
     
         12 . The device as claimed in  claim 10 , wherein the counterholding punch has a calibrating contour which adjoins a punch end on a side facing away from the hollow profile and is designed in accordance with a contour of the secondary feature or of the branch.  
     
     
         13 . The device as claimed in  claim 12 , wherein an encircling collar is formed on the counterholding punch and directly adjoins the calibrating contour on the side facing away from the hollow profile.  
     
     
         14 . The device as claimed in  claim 10 , wherein the end edge of the counterholding punch is rounded.  
     
     
         15 . The device as claimed in  claim 11 , wherein the counterholding punch has a calibrating contour which adjoins the punch end on a side facing away from the hollow profile and is designed in accordance with a contour of the secondary feature or of the branch.  
     
     
         16 . The device as claimed in  claim 15 , wherein an encircling collar is formed on the counterholding punch and directly adjoins the calibrating contour on the side facing away from the hollow profile.  
     
     
         17 . The device as claimed in  claim 11 , wherein the end edge of the counterholding punch is rounded.  
     
     
         18 . The device as claimed in  claim 12 , wherein the end edge of the counterholding punch is rounded.  
     
     
         19 . The device as claimed in  claim 13 , wherein the end edge of the counterholding punch is rounded.  
     
     
         20 . The device as claimed in  claim 15 , wherein the end edge of the counterholding punch is rounded.  
     
     
         21 . The device as claimed in  claim 16 , wherein the end edge of the counterholding punch is rounded.