| 摘要 |
<p>A spacer 44 is inserted between an upper end face 44a of a contact column 40, and a lower face of a flange 14. The flange 14 is supported at plural positions by supporting columns 42. In heating a shoulder portion 16 to a hardening temperature, an electroconductive member 56 is placed close to the shoulder portion 16, and an AC current having a frequency which will cause mutual attraction between the current flowing through the elctroconductive member 56 and the current flowing through the shoulder portion 16 is applied to flow through the electroconductive member 56. The shoulder portion 16 having been heated to the hardening temperature is quenched by ejecting a liquid coolant through ejection outlets of a cooling jacket. <IMAGE></p> |
