Research on flexible asymmetric rolling process for three-dimensional surface parts

Abstract

To realize rapid fabrication of three-dimensional surface parts, flexible asymmetric rolling process for continuously forming surface parts is developed. This process employs an auxiliary roll, a pair of upper and lowers bendable rolls as forming tools. By adjusting the height of the auxiliary roll, the sheet metal is inclined before non-uniform rolling, which is conducive to longitudinal bending deformation of the sheet metal after rolling. Meanwhile, the non-uniform thickness reduction of the sheet metal caused by the non-uniform roll gap between the upper and lower rolls makes itself bend in the transverse and longitudinal directions. Owing to small bending behavior of the bendable roll in the experiment, the forming precisions of formed parts are not ideal by the 3D rolling process without the auxiliary roll. In this paper, the flexible asymmetric rolling process is introduced to improve the 3D rolling process for surface parts with well forming precisions. An auxiliary roll is employed in the flexible asymmetric rolling process except a pair of upper and lower rolls. The formation mechanism of the curved surface is set forth, and the parametric equations of the formed surface in flexible asymmetric rolling process are derived. Typically simulations and experiments for forming spherical and saddle surfaces have been performed. The dimensional accuracies of the forming parts are measured, and the differences of the 3D rolling and flexible asymmetric rolling processes are investigated though numerical simulations. The forming results with good dimensional accuracies show that the flexible asymmetric rolling process is feasible for manufacturing three-dimensional surface parts with a broader range.