Patent ID: 7353977
Filing Date: 2008-04-08
Classification: B23K

Abstract:
1. A frictional joining method, in which different kinds of plural metal members are joined by lapping the metal members, comprising the steps of: providing said different kinds of plural metal members to be joined; forming a metal film having an oxidation-prevention function on a surface of at least one of said metal members which constitutes a joining face between said metal members; lapping said metal members in such a manner that said metal film having oxidation-prevention function is located at the joining face between said metal members; placing a rotating tool on an outside surface of a lapped portion of one of said metal members; joining said metal members by applying a rotational force and a pressing force to said rotating tool, said rotational force being applied around a pressing axis of said rotating tool, said pressing force being applied toward another of said metal members which is joined to said one of metal members on which said rotating tool is placed, wherein said step of joining the metal members includes a step of softening said metal film having oxidation-prevention function located at the joining face between the metal members by the use of frictional heat generated by a rotation of said rotating tool, and a step of pushing out said softened metal film having oxidation-prevention function outward by the use of said pressing force applied to said rotating tool, wherein said pressing force of the rotating tool is adjusted by a pressing stroke of said rotating tool which is moved toward said another of metal members, and said step of pushing out said softened metal film outward is executed by increasing said pressing stroke more than that in said step of softening the metal film, wherein said increasing of the pressing stroke of the rotating tool in said step of pushing out the softened metal film outward is adjusted so as to provide the pressing force that is large enough to push out substantially all of said softened metal film outward such that respective new uncovered surfaces of said metal members directly contact each other, whereby said metal members are joined in a solid state substantially without said metal film having oxidation-prevention function and with a direct contact of the new uncovered surfaces of the metal members at the joining face between the metal members.