Patent ID: 8661677

Claim:
A manufacturing method of a rack shaft comprising the steps of: mounting a shaft raw material on a receiving groove of a lower mold; pressing a part of a peripheral surface of the shaft raw material with an upper mold having a rack-teeth-forming teeth portion formed in a rectangular shape in a bottom view; and oscillating the upper mold with respect to the shaft raw material in a width direction of the receiving groove and around an oscillation center which lies on a center in a width direction of the rack-teeth-forming teeth portion and at a bottom of the rack-teeth-forming teeth portion, thereby forming rack teeth on said part of said peripheral surface of said shaft raw material, wherein the rack-teeth-forming teeth portion has a surface which is inclined with respect to a horizontal line through the oscillation center at substantially the same angle that the upper mold is oscillated and the rack-teeth-forming teeth portion is symmetrically formed with respect to the oscillation center.