Effect of incremental multi-step technology on longitude bending of 3D curved part in continuous roll process

Continuous roll process based on sheet thickness reduction can effectively form 3D curved parts. In the forming process, work hardening is always an important factor for affecting thickness reduction of a rolled plate. In this paper, incremental multi-step forming technology is proposed for the first time, which is different from the previous multi-step forming technology, which only one set of roll gap is needed in the whole forming process. The forming process of convex and saddle curved parts is simulated, and the effect of incremental multi-step forming technology on longitude bending deformation is studied. The results show that in continuous roll process for a 3D curved part, roll gap distribution is uneven, so thickness reduction of the rolled plate is different along the roll gap. By maximizing the thickness difference between the middle and both sides of the rolled plate, the longitudinal bending deformation of the rolled plate is maximized. When the forming steps are one, two, three, and six, the longitude curvature radiuses of forming a convex curved part is 227 mm, 186 mm, 161 mm, and 154 mm in order, so the longitude bending deformation increase to 18%, 29%, and 32% in order; the longitude curvature radiuses of forming a saddle curved part is 239 mm, 185 mm, 167 mm, and 164 mm in order, so the longitude bending deformation increases to 23%, 30%, and 31% in order. Therefore, this technology is suitable for forming 3D curved parts with large bending deformation.