METHOD FOR FORMING STEP ON OUTER PERIPHERAL SURFACE OF SHAFT-SHAPED MEMBER HAVING CIRCULAR SECTION

PROBLEM TO BE SOLVED: To form a stepped part at a substantially right angle on an outer peripheral surface of a shaft-shaped member having a circular section without relying upon cutting work. SOLUTION: An outer peripheral surface of a member is deformed to form an inclined part 24 having an outer diameter that is continuously decreased from a first diameter to a second diameter. The member with the inclined part 24 formed thereon is inserted into a mold 5 that comprises in its interior at least a first inner peripheral surface 61s having an inner diameter substantially equal to the first diameter, a second inner peripheral surface 62s that is connected to the first inner peripheral surface 61s and is extended outward in a radial direction as compared with the first inner peripheral surface 61s, and a pressing surface 62p that is connected to the second inner peripheral surface 62s and has a substantially right angle to a member insertion direction. The outer side of the inclined part 24 is brought into contact with the pressing surface 62p, and from this state, the member is further pressed to deform the inclined part 24 outward in the radial direction, and the member is then pulled out from the mold 5 to allow the material constituting the inclined part 24 moved outward in the radial direction beyond the first diameter to be ironed by the first inner peripheral surface 61s. COPYRIGHT: (C)2011,JPO&INPIT