| 摘要 |
PURPOSE:To prevent the oxidation of alloy components in a blank material and the generation of penetrators in the stage of producing a welded pipe by irradiating a laser beam near the welding point and welding the blank material while allowing the metal in the irradiated part to evaporate. CONSTITUTION:A steel strip is fed and is formed to a U shape; further, it is formed approximately to a circular shape to form an open pipe OP. Both opposed edges of the open pipe are accurately guided and the pipe is fed into an induction heating coil 1. High frequency current is supplied to the coil 1 to heat the opposed side edge parts. The open pipe OP heated at said parts is pressurized with squeeze rolls 3l, 3r and are welded at a welding point A, by which a pipe P is formed. A laser beam generator 7 is installed above the point A, and irradiates a laser beam to the area near the point A. The metallic surface near the point A evaporates and the metallic surface is shielded from the atmospheric air by the vapor pressure thereof, whereby a non-oxidative atmosphere is maintained around the heated parts. |
