Process for producing a rotationally symmetric hollow part and hollow part produced thereby

Abstract

A process for producing a rotationally symmetric hollow part, especially a shaft, including: providing a bar-shaped solid material involving the steps of heating the solid material substantially to forging temperature; cross wedge rolling of the solid material so as to cause weakening in the core zone of the solid material; and inserting at least one rotating mandrel, driven at a predetermined velocity, substantially along the central axis of the cross-wedge-rolled solid material, thus creating a through-hole and to a rotationally symmetric hollow part, especially a shaft.

What is claimed is: 
     
         1 . Process for producing a rotationally symmetric hollow part, comprising the steps of:
 providing a bar-shaped solid material;   heating the solid material substantially to forging temperature;   cross wedge rolling of the solid material in a manner causing weakening in a core zone of the solid material; and   inserting at least one rotating mandrel driven at a predetermined velocity substantially along a central axis of the cross-wedge-rolled solid material in a manner creating a through-hole.   
     
     
         2 . Process according to  claim 1 , wherein said at least one rotating mandrel comprises two rotating mandrels, each of which inserted into a respective one of opposite ends of the bar-shaped solid material. 
     
     
         3 . Process according to  claim 2 , wherein the mandrels are inserted simultaneously. 
     
     
         4 . Process according to  claim 2 , wherein the mandrels are inserted asynchronously. 
     
     
         5 . Cross-wedge-rolled rotationally symmetric hollow part in the form of one of a gear shaft, cam shaft, drive shaft, output shaft, starter clutch shaft, hollow shaft and a preform for other forming parts produced by the process of  claim 1 . 
     
     
         6 . Cross-wedge-rolled rotationally symmetric hollow part according to  claim 5 , wherein the part has a diameter of approximately 30 to 200 mm. 
     
     
         7 . Cross-wedge-rolled rotationally symmetric hollow part according to  claim 5 , wherein the part has a diameter of approximately 60-150 mm. 
     
     
         8 . Cross-wedge-rolled rotationally symmetric hollow part, to  claim 5 , wherein the part is made of a ductile wrought alloy. 
     
     
         9 . Cross-wedge-rolled rotationally symmetric hollow part, according to  claim 5 , wherein the part is made of a material from the group comprising 16MnCrS4, 20MnCr5, and 20MoCrS4 steel. 
     
     
         10 . Cross-wedge-rolled rotationally symmetric hollow part, according to  claim 5 , wherein the part is made of a material from the group comprising a non-iron alloy, aluminum alloy, titanium alloy and magnesium alloy.