METHOD FOR FORMING FLANGE WITH SEAL SEATING FACE AND HEAD FLANGE FOR EXHAUST MANIFOLD FORMED BY THE METHOD

摘要

PROBLEM TO BE SOLVED: To form a flange with a small burring bend radius which can secure a larger seal area than a conventional flange without extending a seal seating face outward in its radial direction whereby the flange can be made compact. SOLUTION: The method for forming the flange with a seal seating face consists of the following three (3) steps of processing. In the first step, a prepared hole a is formed in a workpiece W. In the second step, a flange b is formed by projecting the opening edge of the prepared hole a, and a pad (surplus metal portion) c is formed by projecting the rising portion of the flange b in a direction opposite to the rising direction of the flange b. In the third step, the pad (surplus metal portion) c is crushed and a flat seal seating face d is formed at the periphery of the flange b, positioned closer to the side of the flange b than the apex of the pad (surplus metal portion) c. COPYRIGHT: (C)2004,JPO