Improving bending force prediction in L-die bending process

Abstract

Reducing production costs in sheet-metal forming is often accomplished by carefully matching the press machine capacity to the required forming force. Consequently, press machine capacity can be selected more appropriately when the forming force is predicted more accurately. Existing formulas for L-die bending force calculation demonstrate limited accuracy in predicting the actual force required during the bending process. In this research, the calculation of the L-die bending force was revised based on the L-die bending mechanism, using both the finite element method (FEM) and experimental analysis. Because the bending mechanisms differ between a 90° die angle and a die angle greater than 90°, the L-die bending force prediction required specific modifications for each case. Accordingly, this research proposes two improved bending force prediction models for the L-die bending process under two specific conditions: a die angle of 90° and a die angle greater than 90°. By comparison with the experimental data, the accuracy of the improved L-die bending force predictions was re-evaluated. The results were also compared with the L-die bending force calculation methods currently in use. When comparing the bending forces obtained from experimental work with those predicted by the existing L-die bending force formulas, significant inaccuracies were observed—exceeding 40% for a 90° die angle and 80% for a die angle greater than 90°. However, when comparing the improved L-die bending force predictions proposed in this research with the experimental results, the prediction error was reduced to less than approximately 1%.