| 摘要 |
<p>During the production of a welded pipe from a metal strip by utilizing laser welding techniques, the end portions of a metal strip are preheated so that the temperature of these portions of the metal strip to be laser welded attains a level not lower than a predetermined level, and the preheated end portions are laser welded to produce a pipe, a weld bead on an outer surface and/or an inner surface of the resultant welded pipe being removed by cutting. This predetermined temperature is set in accordance with the thickness of the metal strip and the length of time between the starting of the laser welding and the ending of the removing of the weld bead. In order that the weld bead of a welded pipe obtained can be cut off, the end portions of the metal strip to be welded are preheated before the starting of a welding operation, whereby the hardening of the weld bead, which is ascribed to the rapid temperature drop in a weld zone after the completion of a laser welding operation, is prevented.</p> |
