| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a projection welding method by which the variance of mechanical strength at a welding portion can be prevented. <P>SOLUTION: This method is used to weld a first inner cylinder member 21 (first member) and a second inner cylinder member 22 (second member) at least either of which is formed of a galvanized steel sheet given by primary rust prevention with a post-treatment film. The first inner cylinder member 21 is elastically deformed by press working in a projection formation step, and a projection 24 with an apexθof 50-80 degrees formed by an inclined surface 24b is formed in a cross section parallel to the pressing direction. Thus, the variance of contact resistance at the initial period of energization between the projection 24 and the second inner cylinder member 22 can be prevented in the welding step, and a change in heat generation speed at the initial period of energization can be also reduced. As a result, the difference of attained temperatures due to an increase in temperature is reduced thereafter, so that the variance of mechanical strength at a welding portion can be prevented. <P>COPYRIGHT: (C)2013,JPO&INPIT</p> |
