| 摘要 |
PURPOSE:To prevent a bead from being hardened by arranging an internal bead trimmer in the rear of a post annealer and cutting the inside bead after the post annealing is performed to evade a spark flaw taking place with the post annealer. CONSTITUTION:A weld zone is heated by a work coil 5 and butt-welded by a squeeze roll 6 and the heat of the welded zone is absorbed by a peripheral pipe wall part with the low temperature and the welded zone is quenched and in case a steel pipe is formed by high tensile strength steel or alloy steel, the metallic structure of the welded zone is made to the hardened structure. Next, the welded zone is annealed by the post annealer 7 and becomes soft and is easily cut by the internal bead trimmer 10. Moreover, a spark is generated by the voltage induced by the post annealer 7 and the internal spark flaw is also cut off by the internal bead trimmer 10.
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