A metal mold for plastic working a differential pinion and a method for plastic working with the metal mold.

摘要

The present invention relates to a differential pinion (40) for automobiles or the like, a metal mold (45) for plastic working the differential pinion, and a method for plastic working with the above metal mold. And particularly the differential pinion (40) of the present invention is provided with an end relief section which is effective to reduce a noise and has a continuous fiber flow from a tooth face (44) to the end relief section providing a high pitting resistance. The metal mold for plastic working the differential pinion of the present invention can provide the internal pressure working area of the die (45) in a position deep below by a required distance from the open end, thereby providing the metal mold with higher rigidity and strength. Further, in the plastic working method of the present invention, it is very easy to position the punch (49) under pressure stress in the axial direction.