| 摘要 |
PROBLEM TO BE SOLVED: To obtain the laser welding method which produces no metal particulate by varying at least one of the spot diameter and power density of laser beam irradiating a metallic member and irradiating the same welding place with the laser beam in >=2 stages. SOLUTION: A valve spacer 11 is arranged in contact at a specific position on the outside wall of a convergence cup 10 and the laser beam 13 emitted by a YAG laser oscillator 12 is converged by a condenser lens 14 to irradiate the contact part between the convergence cup 10 and valve spacer 11. In the 1st stage from the start of the irradiation to time t1, the position of the condenser lens 14 and the oscillation output of the laser oscillator 12 are adjusted and the contact part is irradiated with the laser beam having nearly the same spot diameter and power density with conventional laser welding, thereby performing welding to specific welding strength. In the 2nd stage from time t1 to t2, the condenser lens 14 is moved to make the spot diameter 10-50% larger than the spot diameter of the 1st stage, and the weld zone irradiated in the 1st stage is irradiated. |
