Effects of Forming Conditions of Roll Offset Method on Sectional Shape at the Corner of Square Steel Pipe

抄録

Square steel pipes are reshaped from welded round pipes by roll-forming. Effects of the roll diameter on the cross-sectional size of the square steel pipe were investigated by experimentation and three-dimensional finite element simulation. When the top roll diameter is greater than that of the side roll, then the width of a corner part of the formed pipe is greater than the height. The square steel pipe was formed by offsetting the small roll to the upstream side to make the width and height of a corner part equal. The offsetting result is affected by the longitudinal contact distance between a roll and a pipe. The geometric contact length and relative offset, the 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 round pipe wall thickness.