Method for and apparatus of producing outer member of universal joint having cross-grooves

摘要

A method for and an apparatus of producing an outer member of a universal joint having cross-grooves are provided in order to increase replenishability of the inner peripheral portion of the outer member. The outer member 1 is provided in a preformed material including a shaft 1a and a cylindrical portion 1b. A punch set 5 is fitted within the cylindrical portion 1b. The punch set is expandable and constrictable in the radial direction and includes a plurality of protrusions 3 having a configuration complementary to that of the cross-grooves. The cylindrical portion 1b is pressed into a die bore 8, starting with its opening portion 9, for performing an ironing operation.