| 摘要 |
PURPOSE:To shorten a working time and to simplify a working stage by performing rough thread cutting by hot forging or form rolling on a periphery surface of a pipe end just after hot producing the pipe, then finish cutting the pipe after cooling. CONSTITUTION:The blank material 1 for manufacturing the pipe is made as the blank pipe by a piercing mill 30 on the hot pipe manufacturing stage 3 and finished to be the pipe having a prescribed shape and thickness through each apparatus. In the stage having temp. of 600-800 deg.C just after manufacturing the blank pipe, at next rough thread forming stage 4, after a tapered part is formed by forging or rolling on the pipe end, the rough thread is formed. This rough thread worked pipe is cooled on a cooling bed 5 to perform finish cutting on a refining stage 6. Therefore, the rough thread forming is performed while maintaining hot temp., the working time is reduced relative to the usual cutting after cooling, especially on the upset working, the working stage is simplified without reheating.
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