Study On Cross-shear Deformation Based Roll Bending Process And Deformation Behavior Of Sheet Metal With Controllable Curvature

A curvature plate or tubular workpieces are widely used in vehicles,mining,construction and other industries.But the conventional bending process routine has some defects,such as the large inherent bending springback of sheet,the extra processes to pre-curve or remove straight edge,the shortage that can't again a sheet of continuously controllable curvature(such as shape of oval and S,etc.)in one process of machining.In this paper,inspired by the warping defects in plate rolling process,and utilizing the cross-shear warping phenomenon during the process of asynchronous rolling,A cross-shear deformation based roll bending(CSRB)process with controllable curvature is proposed.The active control of plate curvature can be realized by controlling the process parameters such as velocity differential rate and the thickness reduction rate in real time,and then the workpiece with variable curvature can be obtained in one step.This paper mainly studies the deformation law of the processing technology,laying the foundation for its popularization and application.Firstly,the validity of the processing technology had been verified and the law of the bending deformation is discussed.To understand deformation behavior of sheet metal in the process,FEM numerical simulations had been performed.The relationships of the curvature radius of the workpiece and the forming load versus the velocity differential rate and the thickness reduction rate are preliminarily analyzed.In order to the further research on the bending rules,a setup was designed and manufactured.And the experiment was carried out by it.Analyzing the experimental data,we found that the velocity differential rate and thickness reduction rate are the majors affecting factors and thus should be the control parameters of the CSBR process.To achieve better forming,the velocity differential rate should be selected from the left of its forming limit point(the point with the smallest radius of curvature),and the thickness reduction rate.Through the reasonable selection and control of the above process parameters,it is possible to realize the processing of curved plate-shaped workpieces of any continuously varying curvature(within the processing range).Initial thickness and radius ratio of the two rollers are the minor influence factors on the curvature radius in the CSBR process.The FEM simulation results are compared with the experimental results,which proves that the finite element model and the parameter selection are reasonable.