MANUFACTURING METHOD OF OUTSIDE JOINT MEMBER FOR CONSTANT VELOCITY UNIVERSAL JOINT, AND INTERMEDIATE FORGED PRODUCT PROCESSED TO OUTSIDE JOINT MEMBER

摘要

PROBLEM TO BE SOLVED: To inexpensively manufacture an outside joint member of a constant velocity universal joint having a desired shape and rigidity.SOLUTION: There is provided a manufacturing method of an outside joint member which has a bottomed cylindrical cup part whose one end is opened, and in which a plurality of track grooves extending to an inside diameter face of the cup part are formed. The outside joint member is manufactured through a pre-forging process for molding a rod-shaped raw material into an intermediate forged product 21 having a bottomed cylindrical cup-shaped part 22 in which track grooves are roughly molded at the inside diameter face, and a grueling process for molding the intermediate forged product 21 into a final forged product having track grooves having finished shapes. In the pre-forging process, the intermediate forged product 21 is molded in which a diameter-expanded face 24 in a direction in which an elastic deformation margin of the cup shaped part 22 is gradually increased accompanied by the progress of the grueling process in the succeeding grueling process is formed at an outside diameter face 23 of the cup-shaped part 22.