Hollow drive shaft using upsetting method and manufacturing method therefor

Abstract

Provided are a hollow drive shaft using an upsetting method and a method of manufacturing the same, in which hot forging and upsetting processes are applied to both ends of a workpiece so that an outer diameter at both ends of the workpiece is greater than an outer diameter of a middle part of the workpiece, thereby reducing a weight of the drive shaft and enabling the drive shaft to transmit higher driving power. According to the present invention, the upsetting process is applied during the hot forging process to manufacture the hollow drive shaft, portions to be substantially processed are limited to portions at both ends of the workpiece, and the number of upsetting processes is limited to a minimum number (2 or the like), such that initial investment costs and manufacturing costs are low because the number of processes is small.

1 .- 8 . (canceled) 
     
     
         9 . A hollow drive shaft for a vehicle, comprising:
 a middle part having a hollow portion therein as a middle portion of the drive shaft; and   both ends having a hollow portion therein to communicate with the middle portion,   wherein the both ends of the hollow drive shaft has a greater thickness than the middle portion by applying an upsetting process including heat treatment.   
     
     
         10 . The hollow drive shaft of  claim 9 , wherein the hollow drive shaft is formed by inserting a mandrel into a through hole of a steel pipe between a forming die and a punching die by the upsetting process. 
     
     
         11 . The hollow drive shaft of  claim 10 , wherein the hollow drive shaft is manufactured by decreasing the overall length as the cross-sectional area of the steel pipe is increased by the upsetting process. 
     
     
         12 . The hollow drive shaft of  claim 9 , wherein the hollow drive shaft is manufactured without cold forging of the swaging process or sub-component coupling of friction welding. 
     
     
         13 . The hollow drive shaft of  claim 9 , wherein the hollow drive shaft is for increasing a diameter of a constant velocity joint and a ball cage fastened to both ends of the hollow drive shaft and increasing the number of balls of the ball cage to transmit higher driving power. 
     
     
         14 . The hollow drive shaft of  claim 9 , wherein the both ends are, by the upsetting method, a larger outer diameter than the middle portion, the same outer diameter as the middle portion, the same inner diameter as the middle portion, or a smaller inner diameter than the middle portion.