Analysis of the punch motion curve for the springback of U-shaped sheet metal

Servo presses achieve high formability by using different punch motion curves, thereby increasing their applicability in conventional processing fields. In this study, the punch motion curves of servo presses were optimized, and the effects of punch motion curves on the springback of U-shaped sheet metal were explored. Subsequently, the optimal punch motion curve was determined, and the springback effect after processing was investigated. Different punch motion curves were proposed and simulated for comparison with the results of conventional methods, and the equivalent stress values obtained using different motion curves and mold angles were analyzed. DEFORM software was used to conduct simulations to determine the differences between processing methods. In addition, the spring-go, springback, load–stroke characteristics, and stress and strain distributions of U-shaped sheet metal were investigated. The conventional motion curve resulted in springback, stress, strain, and required processing force higher than those achieved by the curves proposed in this study. The smaller the movement difference in the motion curve of the servo press was, the lower the springback, stress, and strain were. These results indicate that the punch motion curves obtained for different types of processing can serve as a reference for selecting appropriate parameter values for servo presses.