| 摘要 |
PROBLEM TO BE SOLVED: To bend a tubular body of non-circular section with a minimum curvature without difficulty by forming a recess on the inner side of the neutral line at a curved part of the tubular body. SOLUTION: In a method for bending the tubular body of non-circular section where the tubular body is fixed and held by inserting a mandrel (core) 24 inside the tubular body from one end of the tubular body 1, when the tubular body 1 is to be bent at the required angle by the rotation of a rotary bending die 30, the tensile force/thrust is applied to one end part of the tubular body 1 to be bent corresponding to the deformation resistance by the depth of the recessed part 3, so that the tubular body 1 is bent to the required angle while forming the recessed part 3 on a part of the inner side of the neutral axis at a bend 2 of the tubular body 1 to be bent along the axis.
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