| 摘要 |
PCT No. PCT/JP92/00016 Sec. 371 Date Jul. 14, 1993 Sec. 102(e) Date Jul. 14, 1993 PCT Filed Jan. 10, 1992 PCT Pub. No. WO93/13891 PCT Pub. Date Jul. 22, 1993.The present invention is adapted to form, at the center of a plate-like metallic blank, a case-like boss projecting from one lateral side of the blank, by: curving the plate-like metallic blank such that the blank is convex punching a hole in the top of the curved blank: and bending an arcuate portion of the blank between an outer peripheral edge portion and a hole peripheral portion of the blank in the direction opposite to the convex direction thereof with the outer peripheral edge portion of the blank restrained from extending radially outwardly. Thus, the method of the present invention is adapted to form, with the use of a small press machine, a boss having a sufficient thickness and a sufficient projecting height even though the boss has a small inner diameter, without the thickness of the initial material reduced so much in the course of the production steps. |
