Method and device for the production of varying elements

Abstract

The invention relates to a method and a device for producing secondary form features on a circumferentially closed hollow profile. The device comprises an internal high pressure forming tool, into the impression of which a hollow profile blank can be inserted, a branch branching off radially from the impression, into which branch the hollow profile blank can be expanded by means of a fluidic internal high pressure, with the secondary form feature being formed. So that secondary form features configured in virtually any desired manner from the point of view of the form profile can be formed on the hollow profile in a simple manner and in a reliable manner in terms of the process, it is proposed that the device, furthermore, comprises a diaphragm and a pressure generator, by means of which pressure can be applied to the diaphragm via a pressure medium in such a way that the diaphragm, during the expansion, bears in a supporting manner against the forming secondary form feature against the expansion direction. The diaphragm gives way elastically with the progress of the forming of the secondary form feature until the final shape is achieved. In this case, the diaphragm is attached to the tool in such a way as to span the branch outside the longitudinal extent of the impression.

1 . A method of producing secondary form features on a circumferentially closed hollow profile, a hollow profile blank being expanded by means of a fluidic internal high pressure into a branch branching off from an impression of the internal high pressure forming tool, with the secondary form feature being formed, characterized in that the forming secondary form feature ( 23 ), by means of a diaphragm ( 10 ) to which an external pressure is applied, is supported against the expansion direction during the expansion in such a way that the diaphragm ( 10 ) gives way elastically with the progress of the forming of the secondary form feature ( 23 ) until the final shape is achieved.  
     
     
         2 . The method as claimed in  claim 1 , characterized in that the secondary form feature ( 23 ) is supported by a supporting pressure which increases with the progress of the expansion.  
     
     
         3 . A device for producing secondary form features on a circumferentially closed hollow profile, having an internal high pressure forming tool, into the impression of which a hollow profile blank can be inserted, a branch branching off radially from the impression, into which branch the hollow profile blank can be expanded by means of a fluidic internal high pressure, with the secondary form feature being formed, characterized in that the device comprises a diaphragm ( 10 ) and a pressure generator, by means of which pressure can be applied to the diaphragm ( 10 ) via a pressure medium in such a way that the diaphragm ( 10 ), during the expansion, bears in a supporting manner against the forming secondary form feature ( 23 ) against the expansion direction, the diaphragm ( 10 ) giving way elastically with the progress of the forming of the secondary form feature ( 23 ) until the final shape is achieved, and in that the diaphragm ( 10 ) is attached to the tool ( 1 ) in such a way as to span the branch ( 4 ) outside the longitudinal extent of the impression ( 2 ).  
     
     
         4 . The device as claimed in  claim 3 , characterized in that the diaphragm ( 10 ) is fastened in an annular recess inside the branch ( 4 ).  
     
     
         5 . The device as claimed in  claim 3 , characterized in that the diaphragm ( 10 ) is fastened to the rear side ( 12 ) of the impression-carrying forming tool ( 1 ) at the end ( 9 ) of the branch ( 4 ).  
     
     
         6 . The device as claimed in one of  claims 3  to  5 , characterized in that the device contains a supporting plate ( 17 ) which covers the branch ( 4 ) at the location of the final position of the end face ( 24 ) of the secondary form feature ( 23 ) on the rear side of the diaphragm ( 10 ).  
     
     
         7 . The device as claimed in  claim 6 , characterized in that the supporting plate ( 17 ) is at a distance from the diaphragm ( 10 ) unloaded with regard to a supporting and/or internal high pressure.  
     
     
         8 . The device as claimed in either of claims  6  or  7 , characterized in that a pressure passage ( 18 ) runs in the supporting plate ( 17 ), this pressure passage ( 18 ) being connected to the pressure generator on the one hand and opening out on sides of the diaphragm ( 10 ) on the other hand.  
     
     
         9 . The device as claimed in one of  claims 3  to  8 , characterized in that the final position of the end face ( 24 ) of the secondary form feature ( 23 ) is at a distance from the pressure-relieved position of the diaphragm ( 10 ).  
     
     
         10 . The device as claimed in one of  claims 3  to  9 , characterized in that the pressure medium transmitting the supporting pressure is liquid or gaseous.  
     
     
         11 . The device as claimed-in one of  claims 3  to  10 , characterized in that the diaphragm ( 10 ) is made of a low-friction material or is provided with a low-friction coating.  
     
     
         12 . The device as claimed in one of  claims 3  to  11 , characterized in that the device comprises a bypass line which connects the pressure line of the internal high pressure to the pressure line of the supporting pressure and contains a controllable valve which keeps the bypass line closed during the expansion and opens the bypass line after the final position of the end face ( 24 ) of the secondary form feature ( 23 ) has been reached.