| 摘要 |
PURPOSE:To increase a holding-down effect of a pool and a penetration depth by dividing a shield gas flow into the vicinity of an electrode for surrounding the electrode and also its outside periphery, and changing physically and chemi cally a quality of the divided gas flow. CONSTITUTION:An inner nozzle 3 having the first shield gas jet port 5 and an outer nozzle 4 having the second shield gas jet port 6 are provided on the periphery of an electrode 2. A jet gas of the nozzle 4 is made to have a quantity required for preventing the periphery of a pool from being oxidized, and a jet gas of the nozzle 3 is made to have a jet pressure required for holding down the pool. As for the jet gas of the nozzle 3, the penetration is increased by using He as necessary, and also a ratio of Ar and He is increased or decreased in accordance with a variation of a welding position. In this way, a holding-down effect of a pool and a penetration depth can be increased without increasing a use quantity of a shield gas. |
