Implementation of Real Contact Areas into Sheet metal Forming Simulations using Digital Spotting Images

Increasing demands on quality of outer car panels and shortened product development processes fundamentally challenge automotive manufacturers. Development times are significantly influenced by the manufacturing process of dies, which are introduced by the time-consuming manual grinding operations carried out during die try-out. Blue color paste is often used to visualize contact areas between die surfaces and blank to provide a spotting image. The spotting image can be used to evaluate and optimize the pressure distribution. A homogeneous pressure distribution positively influences the forming process in terms of flange draw-in and surface quality. This paper presents an approach for implementing real contact areas into forming simulations based on digital spotting images of active surfaces. Spotting images were produced for different drawing depths and subsequently extracted by image processing. The simulation model presented in this study includes different spotting levels in conjunction with the TriboForm friction model to describe tribological conditions during forming more accurately.