| 摘要 |
PURPOSE:To reduce a sectional deformation amt. by bending and to improve the efficiency in working by inserting 1st and 2nd core metals with their abuttment in the state of interposing the respective projecting piece into a square pipe and bending it by situating along the apex face of a bending die. CONSTITUTION:Two core metals 10, 32 are inserted for the square pipe 70 set on a bending die 58 to adjust so that the step difference part 24 of the core metal 10 is located on the curved boundary zone of a horizontal face 62 and inclined face 64 in the main body 60 of a bending die 57. When a force F is acted by an oscillating pressor 72 on the square pipe upper face in the state of floating from the spex face of the main body 60, the square pipe 70 is bent as shown by a alternate long and two short dashes line and its lower face lies along the inclined face 64 of the bending die 58. The curved shape of the main body 60 apex face of the bending die 58 is given to the lower wall of the square pipe 70 and the curved shape of the projecting piece 14 upper face of the core metal 10 is given to the upper wall of the square pipe 70 to bend the square pipe 70.
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