| 摘要 |
PROBLEM TO BE SOLVED: To make good bending possible by stabilizing a plastic deformation of a part where the wall thickness of the inner side in bending increases when a metal tube having a large wall thickness is continuously subjected to hot bending. SOLUTION: Among inner face parts facing the tube outer face of an inductor to conduct induction-heating to a small region in the tube axial direction of a metal tube 11, the profile 40 in the tube axial direction of the part facing the tube outer face 11b having a large increase in the wall thickness of the metal tube 11 is made to the shape following roughly at a fixed gap to a tube outer face 11b, heating of the metal tube 11 is stabilized, the generation of an uneven deformation due to temp. variation is suppressed, thus, good bending is made possible.
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