| 摘要 |
PROBLEM TO BE SOLVED: To perform bending work approximating a required curve shape by series of operations by also making partial bending of the bend forming part after that perform by using the same bending die from the minimum bend corner part in the bending work of a tubular material having a special-shaped cross section for comprising a frame. SOLUTION: When bending the tubular material 1 having the special-shaped cross section, the bending work is performed, first, by forming the bent part 2 having the minimum radius of curvature by using a rotary bending die which is conformed with the minimum radius of curvature as an object frame member, after that, moving the tubular material 1 on which the bent part 2 is formed to the position where is the flexural center by the rotary bending die at prescribed intervals P1, P2 and forming the partial bend sections 3 after the bend part 2 having the minimum radius of curvature into the curve shape at an apparent large curvature by successively applying operations for bending the tubular material at shallow anglesθ1,θ2 to a plurality of places. COPYRIGHT: (C)2004,JPO
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