| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a pulsed laser welding method enabling proper welding without such poor welding on a welded area as hole-making or inner-diameter- narrowing. SOLUTION: In the welding method, a protective tube 6 comprises a thin- walled small diameter pipe 6A and a thin-walled large diameter pipe 6B monolithically-containing a boss section 30. An open end of the small diameter pipe 6A is fitted in the boss section 30 by insertion, and a pulsed laser beam is radiated on a welding area A to provide laser welding between the small diameter pipe 6A and the boss section 30. For the welding, the welding area of the boss section 30 is melted by heating from pulsed laser beam radiation. After each welding completion by 1 shot, the welding area is always cooled for a definite period of time to be solidified as well as the protective tube 6 is rotated to the required angle so as to circumferentially lap a part of next welding area over the former welding area. By repeatedly providing such a pulsed laser welding, the boss section 30 is circumferentially-welded with the small diameter pipe 6A.</p> |
