| 摘要 |
PURPOSE: To improve welding speed in the laser welding method of a welded steel tube. CONSTITUTION: A steel strip 1 conveyed continuously is formed cylindrically; the abutting part 2 of both edges of the steel strip is irradiated and welded by a laser beam 3, simultaneously, a gaseous mixture of CO2 and Ar is supplied from the inside of the tube to the welding zone by means of a gas supply nozzle 4 in the range where CO2 /(Ar+CO2 ) is 10-25%, and the welding is performed while the welding width W of the inside of the tube is expanded by the gaseous mixture. |
