| 摘要 |
PROBLEM TO BE SOLVED: To avoid decrease of productivity and increase in equipment investment by preventing metallic powder from sticking to a valve seat member and by performing welding and demagnetizing of the valve seat member by means of the same equipment. SOLUTION: In the welding process, a welding current of about 90 kA×1 pulse (0.1 to 0.6 sec) is fed in the positive direction. After the welding process, a reheating current of about 30 to 50 kA×1 to 5 pulses (0.1 to 3.0 sec) lower than the welding current is fed in the negative direction (reverse direction) for reheating the valve seat member by the resistance heat generation. Thereby a hardened layer inside the valve seat member is tempered, and simultaneously the magnetic force of the magnetized valve seat member is relaxed by generating a magnetic field in the reverse direction as compared with that of the welding process. COPYRIGHT: (C)2004,JPO |
