Method of manufacturing a hollow body by loading such a hollow body blank seated in a cavity with an internal pressure under increased temperature

Abstract

The subject matter of the invention is a method of manufacturing a hollow body ( 1, 10 ) by applying to such a hollow body blank seated in a cavity an internal pressure at increased temperature, wherein said hollow body blank is made using at least one previous forming or master shaping process, said hollow body blank differing by at least 10% in circumferential length on its circumference.

1 . A method of manufacturing a hollow body by applying to such a hollow body blank seated in a cavity an internal pressure at increased temperature, wherein said hollow body blank is made using at least one previous forming or master shaping process, said hollow body blank differing by at least 10% in circumferential length on its circumference. 
   
   
       2 . The method as set forth in  claim 1 , characterized in that the hollow body blank has only one open end. 
   
   
       3 . The method as set forth in  claim 1 , characterized in that the hollow body blank comprises a bottom. 
   
   
       4 . The method as set forth in  claim 1 , characterized in that the bottom comprises an opening. 
   
   
       5 . The method as set forth in  claim 1 , characterized in that, during internal pressure forming at increased temperatures, the hollow body blank is compressed axially in order to prevent undesired reduction of the wall thickness or in order to increase the wall thickness. 
   
   
       6 . The method as set forth in  claim 1 , characterized in that, during internal pressure forming at increased temperatures, the hollow body blank is drawn in order to achieve the desired wall thickness distribution. 
   
   
       7 . The method as set forth in  claim 1 , characterized in that the hollow body is bent before forming or while the cavity is being closed. 
   
   
       8 . The method as set forth in  claim 5 , characterized in that the hollow body blank is compressed at the closed end. 
   
   
       9 . The method as set forth in  claim 8 , characterized in that the hollow body blank is additionally deformed in the region of the closed end during compression. 
   
   
       10 . The method as set forth in  claim 1 , characterized in that the hollow body blank is configured to be spherical and is made by at least one previous forming or master shaping process, said blank comprising at least one opening. 
   
   
       11 . The method as set forth in  claim 1 , characterized in that the hollow body blank has a higher temperature in regions of higher degrees of deformation and/or wall thicknesses than in regions of lower degrees of deformation and/or wall thicknesses. 
   
   
       12 . The method as set forth in  claim 1 , characterized in that the temperature for internal pressure forming is lower than the melting temperature of the material of the workpiece. 
   
   
       13 . The method as set forth in  claim 1 , characterized in that air or an inert gas such as nitrogen or argon is used for applying the internal pressure. 
   
   
       14 . The method as set forth in  claim 1 , characterized in that the hollow body blank is heated partially or completely. 
   
   
       15 . The method as set forth in  claim 1 , characterized in that the cavity is heated partially or completely. 
   
   
       16 . The method as set forth in  claim 1 , characterized in that the hollow body blank and/or the cavity (die engraving) comprises a heat profile with temperature differences preferably ranging between 2° and 100° C. in order to allow for deformation to proceed in the desired deformation sequence. 
   
   
       17 . The method as set forth in  claim 1 , characterized in that the hollow body blank is tempered from the forming heat after forming. 
   
   
       18 . The method as set forth in  claim 1 , characterized in that the hollow body blank consists of several parts that communicate with each other for the forming medium to pass through. 
   
   
       19 . The method as set forth in  claim 1 , characterized in that the hollow body blank is sealed outside the cavity during compression or drawing.