ロールオフセット法によって成形される正方形角形鋼管の
コーナー形状に及ぼす成形条件の影響

抄録

A square steel pipe is reshaped from a welded round pipe by roll forming. The effect of roll diameter on the cross-sectional size of the square steel pipe was investigated by experiment and three-dimensional finite element simulation. When the diameter of the top roll is larger than that of the side roll, the width of a corner part of the formed pipe is larger than the height. The square steel pipe was formed by offsetting the small roll to the upstream side in order to make the width and height of a corner part equal. The result of offsetting is affected by the longitudinal contact distance between a roll and a pipe. Geometric contact length and relative offset (= offsetting distance / geometric contact length) were defined. The optimum value of the relative offset was clarified, which increased with the expansion of the contact length of a top roll, the roll gap, and the wall thickness of a round pipe.