| 摘要 |
<p>A spacer 44 is inserted between the upper end surface (40a) of a contact column (40) and the lower surface of a flange (14), and the flange (14) is supported at a plurality of places by support columns (42). Further, in heating a shoulder (16) to the hardening temperature, an electrically conductive member (56) is placed close to the shoulder (16), and an alternating current of such frequency that the currents flowing through the electrically conductive member (56) and through the shoulder (16), respectively, are attracted toward each other is passed through the electrically conductive member (56). After the shoulder (16) has been heated to the hardening temperature, it is quenched with a cooling liquid emitted from the jet port in a cooling jacket.</p> |
