Electromagnetic blank holding system for flexible segmentation in forming of complex parts: a flow rate-based design, configuration, and validation

Using a segmented holding system can effectively reduce cracking and wrinkling in the stamping process and improve the forming limit of stamped parts. Different segmentation schemes can be achieved flexibly using a blank holding system driven by electromagnetics. However, how to segment the blank holder to fulfill the demand for flow control of complex parts is still an obstacle to overcome. This paper proposes a flow rate-based design of distributed blank holders on demand for complex parts. A theoretical model is first established to analyze the differences in flow rate in the flange. Then, the flow rates are identified circumferentially and radially to find the locations where the changes in rates are large, and these locations are lined and deemed as the boundaries for segmenting holders. Moreover, a design implementation, including location identification and the electromagnetic system configuration for complex parts, is developed to explore the optimal segmentation schemes. To validate the effectiveness, the downscaling part of a car door with the material DP600 is selected to find the segmented scheme, and the corresponding prototypes of integral and segmented electromagnetic dies are then configured. Experimental results show that the thickening ratio is decreased by 15.4%, and the thinning ratio is increased by 22.5% compared with that of the integral blank holder, and the design achieves better quality and fewer segmented pieces compared with the conventional approach. This research assists in designing segmented blank holding systems enabled by electromagnetics and provides a universal segmentation approach to form better-quality complex parts.