| 摘要 |
PURPOSE:To prevent inclusion of air into the work by providing an auxiliary flow passage through which a protecting gas passes near the end of a nozzle head on the side opposite from the work and expelling the air in the nozzle head by the negative pressure developed by the gaseous flow. CONSTITUTION:Laser light 2 is passed into the hole 2A of a nozzle head 6 and an auxiliary gas 7a is admitted through an aixiliary flow passage 7, and is blown to the surface of the work 4. In this stage, the flow of the gas 7 includes air therein and generates discoloration and welding defects in the work 4. Therefore, a gas flow passage 9 for flowing of a protecting gas 10 is mounted adjacently to the head 6, and the gas 10 is run so as to cross the laser light 2. Since the circumference of the gaseous flow is held under negative pressure, the air interposing in the head 6 is drifted toward the same and is discharged together with the gaseous flow to the outside. Thus the air is expelled from the surface of the work 4 and the surface is covered thoroughly with the gas 7b. |
