Patent ID: 6457340
Filing Date: 2002-10-01
Classification: B21D

Abstract:
A method of forming a boss-integrated sheet metal member made from a circular sheet metal blank, comprising the steps of boring a circular hole at a center portion of the circular sheet metal blank; curving the circular sheet metal blank into a shape which projects toward a projection side of the boss; and bending and pressing a part of an inclined portion of the curved circular sheet metal blank between the outer peripheral edge portion of the circular sheet metal blank and the circular hole in a direction opposite to the projection direction, while holding the center portion containing the circular hole from moving and restricting a radially outward spread of an outer peripheral edge portion of the circular sheet metal blank which has undergone said curving step, thereby bending the inclined portion into a recessed shape to form a case-like boss in which the circular hole serves as a tip end opening, whereinsaid boring step and said curving step are sequentially conducted in an arbitrary order, and said bending step is then conducted while the circular hole is positioned at a reference position.