To realize a method for easily producing a high precision ring 8 serving as a base stock for forming a raceway ring constituting a radial ball bearing by a cold working.
A disk-like intermediate base stock 22 shown in (B) is formed from a billet 21 shown in (A) and a circular intermediate base stock 26 shown in (D) is formed through a second disk-like intermediate base stock 24 shown in (C). This circular intermediate base stock 26 is subjected to inverse working for changing the cross-sectional shape at 90° angle in such a direction that the inner diameter side having large thickness size is made large and the outer diameter side having small thickness size is made narrow. Then, a cylindrical high precision ring 8 having the regulated values of the inner diameter, the outer diameter and the axial directional length, is formed.
OTSUKA SEIJI
MORI KOHEI
Nakai Shun
Kinzo Koyama