To reduce the manufacturing cost of an annular component by a sequentially forming method without degrading the quality of a product.
A hole 22 is drilled through a disk-shaped work 20 by a drill 24, and a mandrel 30 is passed through the hole 22 to perform the sequential forming. Thus, an annular component forging/punching step by the hot forging is unnecessary for a preparation step for performing the sequential forming. The disk-shaped work 20 can also be obtained by other methods (such as punching of a plate and cutting of a columnar member) without using the hot forging, and any increase in manufacturing cost by the hot forging can be prevented. Further, material loss is only by scraps created when drilling the hole 22 by the drill 24, and the yield of the material is considerably enhanced.
COPYRIGHT: (C)2008,JPO&INPIT
ODA FUTOSHI
Miyazaki Yoshio
Kaoru Onozuka
Akio Tagami
High Masahiro
Toshio Nakamura