Practical approach of simultaneous optimization of variable blank holder force and variable slide velocity trajectory in sheet metal forming

Variable blank holder force (VBHF) that the blank holder force varies through the stroke is recognized as one of the advanced manufacturing technologies for sheet metal forming. On the other hand, slide velocity (SV) that controls the die velocity is rarely discussed in the literature. In particular, variable SV (VSV) that the SV varies through the forming process is an attractive forming technique for improving the product quality and the productivity. This paper proposes a practical approach of optimization of VBHF and VSV trajectory for sheet forming. First, based on the experimental result, the finite element analysis model is developed. Then, a multi-objective design optimization considering the product quality and the productivity is performed. A sequential approximate optimization that response surface is repeatedly constructed and optimized is adopted to identify the pareto-frontier. Three points on the pareto-frontier are selected, and the experiment using the servo press (H1F200-2, Komatsu Industries, Corp.) is conducted. Through the comparison of numerical and experimental results, the validity of the proposed approach is examined.