Roll forming process of automotive seat rail with 980 DP steel using Yoshida-Uemori kinematic hardening model

Abstract Roll forming is a continuous manufacturing process used to obtain long parts with constant cross-sections. During the process, sheet metal from coils or pre-cut blanks is bent plastically along a linear axis. In this study, a roll process for forming an automotive seat rail lower part using 980 DP was developed. This model has an asymmetric shape and requires a process in which the central portion is bent opposite to the direction for bending at both ends and, is then bent again in the forward direction. In this process, kinematic hardening should be applied to predict springback. The Yoshida-Uemori model was used as a representative kinematic hardening model in this study. Tensile tests and tensile-compressive cyclic loading tests were performed on 980 DP steel to obtain the parameter values for the Yoshida-Uemori model. Finite element analysis was performed using the commercial code LS-DYNA. With the aid of finite element analysis, 30 stages of the roll forming process were designed and tried out in actual use. Finally, the roll-formed seat rails fulfilled the quality requirements.