Modeling for warping prediction and control in cold rotary forging of round plate

Abstract

Cold rotary forging is an advanced plastic forming method, which is especially suitable for forming round plate attributed to its continuous local plastic deformation characteristics. However, the warping defect is easy to occur in cold rotary forging of round plate owing to the eccentric load exerted by the conical top die, which may lead to poor forming accuracy and even the waste of formed round plate. This paper is aimed to establish the model for warping prediction and control in cold rotary forging of round plate. Firstly, the model for calculating the stress state of time-varying contact region between top die and round plate is established, and consequently the actual circumferential stress of uncontacted region of round plate is obtained. Based on the geometric and material parameters of uncontacted region, the critical circumferential stress of warping can be obtained. By comparing the actual circumferential stress and critical circumferential stress, the critical conditions of warping are obtained. Then, the model for calculating the warping amount is established based on the boundary stress state of uncontacted region. By analyzing the warping amount of different positions, two warping modes are found under different geometric and processing parameters. Meanwhile, the judgment criterion and critical windows for the two warping modes are established. Finally, a novel warping control method is proposed and the corresponding control model is established. The FE simulation and experimental results demonstrate that the established model for warping prediction and control in cold rotary forging of round plate is effective.