The upsetting step which by the fact that it stores the work which consists of

摘要

PROBLEM TO BE SOLVED: To reduce as much as possible a forging forming process and a number of components necessary for the forming of a shaft having a large diameter part and a projecting part which extends from the large diameter part, and to reduce a manufacturing cost.;SOLUTION: A forming device 10 has a fixing part 12 and a movable part 14. The sleeve punch 70 is fitted in a hole part 68 of a sleeve punch holder 60 which forms the movable part 14. An inner punch 74 which is vertically movable freely in a hole part 72 under an action of a piston 78 is inserted in the hole part 72 of the sleeve punch 70. Firstly, a work W inserted in a cavity 44 is pressed by the sleeve punch 70 and the inner punch 74, and a tapered shape stage parts 3a and 3b and a large diameter part 4 are installed. Then, while pressing only by sleeve punch 70 is continued, the inner punch 74 is raised. By a plastic flow of a metal of the work W to be built up following to the raised inner punch 74, a projecting part 5 which is extended from the large diameter part 4 is formed.;COPYRIGHT: (C)2003,JPO