| 摘要 |
PURPOSE: To eliminate possibility of deforming a molten pool and to enable laser welding with a high shielding performance by exhausting a lubricant decomposed gas by means of a strong cylindrical gas flow and shielding water vapor and the like by means of a weak columnar gas flow. CONSTITUTION: When a welding part W2 of a metallic belt W is irradiated with a laser beam 18 from outside a tube, the shield gas inside the tube of a welding part W2 is constituted of a weak columnar gas flow 21 and a strong cylindrical gas flow 22 enclosing the weak one, and the inside diameter of the cylindrical gas flow 22 is made larger than that of a molten pool W3 . The weak columnar gas flow 21 prevents the air or water vapor of which the shield gas from a second gas nozzle 16 overflows from a thorough-hole 13 and heads for the molten pool W3 ; the strong cylindrical gas flow 22 is formed from a first gas nozzle 15, preventing the air or water vapor heading for the lower face of the molten pool W3 and exhausting the heat decomposed gas of a lubricant. Thus, a laser welding with a high shielding performance is made possible without deforming the molten pool W3 . |
