Numerical and Experimental Parametric Study on the Mechanism of Web-Warping in Chain-Die Forming with Variable Cross-Section

Chain-die forming is a new sheet metal forming process, which can be used to produce complex and variable cross-section UHSS automotive structural parts. In this paper, the web-warping and the longitudinal strain developed in the sheet metal during the chain-die forming process are investigated by the finite element analysis, and the accuracy of the model is verified by the experimental work by comparing the longitudinal strain of the product with a forming angle of 60°. The reasons for web-warping in chain-die forming and the effects of different process parameters on web-warping are analyzed. The results show that the side leg height has the most significant effect on the longitudinal strain development, followed by material strength, sheet metal thickness and turning radius. Likewise, the linear regression model confirms that the material strength has the most significant effect on the web-warping height while the forming angle and side leg height have less influence during chain-die forming variable cross-section profile.