METHOD AND APPARATUS FOR MANUFACTURING HOLLOW COMPOSITE MAGNETIC MEMBER, AND FUEL INJECTION VALVE

摘要

A method for manufacturing a hollow composite magnetic member in which magnetism is weakened in a part of a ferromagnetically formed hollow member, the method including a step of forming a feebly magnetic region in which magnetism is weakened by continuously supplying a Ni-containing material to a part of the hollow member while heating a line segment of an irradiation region with a laser beam so as to melt and mix the Ni-containing material and the hollow member. In this way, cave-ins which tend to be caused by a feeble magnetization process in a local area of a hollow ferromagnetic pipe can be prevented; deformation caused by laser irradiation can be greatly decreased; and the need to adjust the shield gas pressure in the pipe can be eliminated, thereby making it possible for a higher efficiency and higher quality feeble magnetization process to be performed.