| 摘要 |
PURPOSE:To prevent the thickness increase on the bend inner peripheral side and to obtain the bend pipe with uniform thickness by cutting the pipe wall of the bend inner peripheral side at the part where a bend deformation is caused or at the position before that. CONSTITUTION:The pipe 3 to be bent is held by a tail stock and whirling arm and heated in annular shape of narrow width zone by an inductor 22 from the pipe inner face. When the tail stock is advanced in this state, the annular heating part is moved in the longitudinal direction of the pipe and simultaneously a bend moment is applied on the pipe 3 by the whirling arm and bend deformation is performed from the annular heating part. The continuous bending is performed by rapidly cooling with the cooling water from a cooling device 35 immediately thereafter. In this case, the pipe 3 has the tendency to become flat at the bend deforming time, but due to the 1st and 2nd mandrels 20, 21 being arranged inside the pipe, the flattening of the pipe cross section is prevented and yet the thickness increasing part due to the bend is bulged to the outer face side of the pipe at the bend inner peripheral side. This bulging part is cut and removed by the cutter 31 which is driven with turning by a motor 33. In this way the bend pipe having the pipe wall in comparatively uniform thickness is obtd.
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