Control of Defects in Deep Drawing of Tailor-welded Blanks for Complex Shape Automotive Panel

With the development of lightweight vehicles, tailor welded blanks (TWBs) are increasingly used in the automotive industry. Splitting and wrinkling are the main defects during the deep drawing of TWBs. A new method to control the forming defects was introduced in the forming process of TWBs in this study. The microstructure and mechanical properties of TWBs were characterized through metallography and tensile tests. Finite element modelling of an automobile rear door inner panel made of TWBs was built to analyse deep drawing. Edge cutting and notch cut were introduced in the drawing to deal with forming defects and reduce the number of stamping tools. The minimum distance between the material draw-in and trimming lines, thinning index and thickening index were defined as the measurable index to analyse the numerical results. Orthogonal experiment, numerical simulation and multiobjective experiment were utilised to optimize the forming parameters. The proposed method and optimised parameters were verified through experiments. The experimental results are basically consistent with the numerical simulation. Results demonstrate that the proposed method can provide some guidance for controlling the defects in deep drawing of TWBs for complex shape automotive panel.