Punch For Producing Holes In The Wall Of Hollow Parts Subjected To The Action Of Internal High Pressure

Abstract

A punch designed for producing holes in the walls of hollow parts, the part being subjected to the action of high pressure in the interior by a medium during the punching. In particular when producing hollow parts by the internal high pressure forming process, it is normal practice, following the forming and with the part still located in the forming tool, to make holes in the wall. In order to avoid a drop in the internal high pressure when cutting through the wall of the part, the punch is designed so as to taper at an angle toward the cutting edge in its region plunging into the part to be punched. As a result, sealing of the hole occurs during the punching.

1 - 3 . (canceled)  
     
     
         4 . A punch for producing holes in the wall of hollow parts subjected to the action of internal high pressure and accommodated in the mold of an internal high pressure forming tool, wherein the punch is designed to be pushed from the mold wall into the mold interior space, said punch comprising: 
 a first portion; and    a tapered portion having a cutting edge, wherein said tapered portion extends from said first portion to said cutting edge at an angle whereby, when said punch plunges into a part to be punch, a sealing surface between said part and said punch is formed.    
     
     
         5 . The punch as claimed in  claim 4 , wherein the punch, in its initial position, is arranged in the mold in such a way that the cutting edge is set back relative to an inner wall of the mold.  
     
     
         6 . The punch as claimed in  claim 4 , wherein the angle of taper is greater than 0° and is at most 30°.  
     
     
         7 . The punch as claimed in  claim 5 , wherein the angle of taper is greater than 0° and is at most 30°.  
     
     
         8 . The punch as claimed in  claim 6  wherein the angle of taper at least 1° and at most 3°.  
     
     
         9 . The punch as claimed in  claim 4 , wherein the tapered portion is conically constructed whereby material in the region of walls of the punched hole is upset.