Spring-back factor applied for V-bending die design

Abstract

To fabricate various parts with complex shapes in the sheet-metal bending industry, the V-die bending process is commonly applied. To achieve precisely bent sheet-metal parts, the design of a proper V-bending die which could prevent the spring-back characteristic and obtain the required bend angle as well as control and maintain the required bend radius is needed. The predicted spring-back and bent radius could be basically calculated by using the spring-back factor. In the present research, therefore, the accuracy of the spring-back factor for bend angle prediction and bend radius calculation in the V-die bending process was examined based on the finite element method (FEM) and laboratory experiments. The two existing spring-back factors, including the conventional and adjusted spring-back factors, were investigated. The results showed that, compared with experimental results, the accuracy of the bend angle prediction and the bend radius calculation obtained using the adjusted spring-back factor were better than those obtained using the conventional spring-back factor. These results were clarified based on the stress distribution analysis of the sheet-metal bent parts. Therefore, the adjusted spring-back factor was recommended over the conventional spring-back factor for V-bending die design applications to achieve a better accuracy bend angle prediction and bend radius calculation.