| 摘要 |
PURPOSE:To enable the bending strenuously restraining the variation in sectional shape by pinching a square pipe by providing a pair of the jigs having the inner face shape corresponding to that of both side faces of the square pipe for working object at the inner side of a pair of jig supporting plates slidable in the axial direction along the outer peripheral face of the roll main body. CONSTITUTION:The jig 9 in the shape and size corresponding to the blank 1 to be worked is provided at the inner side position of each disk 8 in the state of separating a pair of disks 8 by driving a ram 11. The blank 1 is thereafter pinched between jigs 9 by driving the ram 11, disk 8 and jig 9 so as to approach to the blank 1. When the bending is executed by bending rolls 2, 3, 4 in this state, the blank 1 is bent without accompanying the variation in the sectional shape almost because of the remarkable variation of the sectional shape being regulated by the jig 9. And yet for bending of the square pipe in different shapes and sizes the jig 9 may be changed for that in the shape and size corresponding to the square pipe thereof and a quick countermeasure is made possible.
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