| 摘要 |
PURPOSE:To obtain a steel pipe having excellent roundness even with the steel pipe which is low in straightness in line for executing a continuous heat treatment by progressing the steel pipe in the longitudinal direction thereof while rotating the steel pipe around the axial center by providing a steel pipe band straightener to the inlet side of a heat treatment device. CONSTITUTION:The heat treatment device 11 is constituted by arranging a heater 11A such as induction heating furnace and a cooler 11B such as water cooler for the inside and outside surfaces in this order along the progressing direction A of the steel pipe 1 in the line. A heater 12A such as induction heating furnace and a cooler 12B such as water cooler for the outside surface to constitute the bend straightener 12 are disposed in this order along the direction A on the inlet side of the heat treatment device 11. While the steel pipe 1 is rotated by a skew roller table 13 consisting of many skew rolls 10, the steel pipe is passed through the straightener 12 and is further advanced toward the device 11. The steel pipe is thereby treated without the deterioration in the out of roundness after the treatment even in the case of treating the steel pipe with is bent and is low in the straightness and particularly the thin-walled steel pipe having a tendency to lower out of roundness.
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