| 摘要 |
PROBLEM TO BE SOLVED: To prevent the generation of cracks in a valve seat and moreover to excellently position the valve seat to a cylinder head main body while controlling the reduction of the service life of a pressurizing head when the cylinder head main body is joined to the nearly ring shaped valve seat by heating between both members 2, 3 and pressurization using a pair of pressurizing heads (upper side and lower side electrodes) which are mutually faced. SOLUTION: A nearly cylindrical projected part 36a, having a prescribed gap between the whole inner periphery and an electrode 36 at the time when the rear surface of the electrode tip 36 abuts on a valve seat 3, is formed in the rear surface of the electrode tip 36 of an upper side electrode 24, a positioning part 36c is set in the whole periphery of the end part in the side periphery 36b of the projected part 36a, and the transfer in the nearly horizontal direction of the valve seat 3 at the time of pressurization is controlled with the positioning part 36c. |
