| 摘要 |
PROBLEM TO BE SOLVED: To effectively carry out a welding operation, eliminate necessity of tack welding which causes bad influences such as strength deterioration of a base metal, and avoid deterioration of welding accuracy. SOLUTION: The entire member 10 for a welding joint is magnetized in an axial line direction, to form a permanent magnet which is substantially demagnetized at about 240 deg.C. In a normal circumstance where a magnetic field does not substantially exist, a groove gap 18 is provided between edge parts of both steel frames 14, and an arc-shaped section part 12 of the member 10 is outerly engaged in both of the steel frames 14. The member 10 is magnetically adsorbed to both of the steel frames 14 so that the groove gap 18 is positioned at a circumferential direction groove part 16. Under such a condition, a bar is crossed at an axial line direction center part between the edge parts of steel frames 14, whereby welding is carried out while a welding wire does not touch the steel frames 14.
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