| 摘要 |
PURPOSE:To obtain a welding method in an automatic pipe-making machine, in which the shaping of an inner surface bead is executed by welding from the inner surface at the same time from an outer surface, and the operation having high welding speed and industrial stability can be executed. CONSTITUTION:An optical fiber 13 transmitting a laser beam into a cantilever supporting pipe 10 from a laser beam source is inserted and arranged. The optical system, in which the laser beam from the optical fiber 13 is condensed in an inner guide device 12 with a collimater lens 14 and reflected to a collimater lens 17 for irradiation through mirrors 15, 16 arranged at the prescribed angles, is constituted in a laser beam head. Then, at the time of heating the inner surface seaming part with the laser beam, melting of the welding from the outer surface is adjusted to about 80% of the sheet thickness of the base stock 2 for pipe and the part at the downstream side of the advancing direction is heated from just below the melted part by the outer surface input. By this method, the high quality welded pipe which restrains the influence of action of the pressure from upper surface and the gravity and also, controls the inner surface bead by changing the output of the laser beam to be able to correct the offset, side running, etc., in the seam part, is obtd. |
