Effect of Roll Gap Setup on Shape Defects during a Flexible Roll Forming Process

The flexible roll forming process is an advanced sheet metal forming process which manufactures parts with variable cross-section profiles. The metal sheet is incrementally bent into the desired shape by passing it through successive roll stands. In this process, contacts of the flange and web sides are controlled by roll gaps in vertical and horizontal directions. To investigate the effect of the roll gap on shape defects during the flexible roll forming process, experiments were conducted using a lab-scale machine according to different combinations of roll gapsetups: 1) a smaller flange gap than the blank thickness; 2) the same flange and web gaps as the blank thickness; 3) a smaller web gap than the blank thickness. Three kinds of symmetric blanks with trapezoid, concave and convex shapes were used for the experiments. To investigate the effect of the roll gap on shape defects, web-warping and longitudinal strain at the edge for the three different blank shapes were characterized at various combinations of roll gap setups.