Investigation of the design process for the Chain-die forming technology based on the developed multi-stand numerical model

© 2019 Elsevier B.V. The Chain-die forming process is a novel sheet metal forming technology which can be considered as a continuous stamping process. The approach aims to reduce or even eliminate the redundant deformation when manufacturing advanced high strength steel (AHSS) products by utilizing a virtual roll with sufficiently large radius. In previous researches, single-stand finite element models were employed to investigate the characteristics of the Chain-die forming process assuming no interaction between multiple forming stands. However, the effects of inter-distance and elevation of the forming stands have been shown to be significant on product quality in roll forming. In this paper, a new finite element simulation model for a multi-stand Chain-die forming process is introduced and experimentally validated. Meanwhile, an optimization process combining analytical and numerical approaches is proposed to improve the design efficiency. The results show that a multi-stand simulation approach has a much higher accuracy in predicting the development of longitudinal strain in flange edge sections compared with single-stand models. The influence of the elevation of the forming stands is theoretically and numerically investigated and proved to have a significant influence in the peak longitudinal strain. Also, a semi-analytical model for determining the minimum inter-distance for stands involving a single active bend is derived for the Chain-die forming process and compared with simulation results. The developed FE models can represent the multi-stand Chain-die forming process and be utilized in exploring the effect of process parameters. With the aid of a semi-analytical model for predicting the minimum inter-distance required and an analytical model for estimating the reduction ratio from the elevation of the forming stands, the efficiency of the design process can be significantly improved. The findings can assist in optimizing the forming strategy design for products requiring multiple Chain-die forming stands.