Analytical and numerical determination of the forming load in the Chain-die forming process

Recently there has been a growing demand for Advanced High-Strength Steel (AHSS) in the automotive sector because it can offer similar strength and crash resistance at a lower mass. However, conventional manufacturing is having trouble processing AHSS, and many technical issues such as substantial residual strains and unpredictable springback arose during the process. Thus, a new forming technique Chain-die forming was developed to address this situation. Past research has shown the advantage of the Chain-die forming method. However, systematic research and more case studies should be done to further explore the feasibility of the Chain-die forming in industrial practice. In this work, two fast estimation of the forming load methods are proposed. The first method estimates the forming load experienced by the forming device by superimposing the duplicated load curve extracted from a two-dimensional stamping simulation. The second method is an analytical model considering the stretching and bending behaviour of the sheet metal during forming. It is established using the internal deformation energy and the geometric relationship of the toolings and forming devices. Furthermore, this analytical model is based on equating the external work to the internal dissipation of the energy to estimate the forming load. The estimated results have been verified with the experimental data and show good agreement. The findings of this study can be implemented in the future development of Chain-die forming to improve the efficiency of the design and optimisation process.