An investigation on bend curve in the transition zone on web warping of channels with variable width in the flexible roll forming process

Flexible roll forming is a modern process to produce products with variable cross section that can be used in construction and automotive industries. The portion which connects the slim section to the wide one is called transition zone. In this paper, effect of different bend curves on the web warping has been studied in the transition zone. Considering the geometrical boundary conditions of the transition zone, five different curves including circular, quadratic, cubic, quartic, and quintic curves were studied numerically and experimentally. According to the finite element results, longitudinal strains on profile edge which are less than the desirable strain increase the web warping defect. Product with circular bend curve showed the maximum amount of web warping while the quartic bend curve led to the lowest web warping. In order to verify the finite element analysis, the longitudinal edge strain and the web warping were measured in products with Circular bend curve experimentally. A good agreement between the experimental and finite element results confirmed the accuracy of the finite element model.