Prediction of Bend Allowance and Springback in Air Bending

In the fabrication industry, one of the critical challenges is to maintain close geometric tolerances in finished products, particularly in the air bending process. In many cases, this problem is related to springback and plastic elongation/compression of the sheet, as it undergoes deformation in bending. Springback refers to the elastic recovery of the bent sheet after unloading, whereas bend allowance refers to the elongation of the sheet during bending. Both factors, if not predicted properly, may lead to dimensional inaccuracies in the finished product and cause difficulties in the assembly. Therefore, it is essential to predict springback and bend allowance in order to obtain the final desired geometry. A new analytical model was developed to predict springback and bend allowance simultaneously in air bending, and a user-friendly computer program, BEND (Version 3.0), was developed. Results obtained from the BEND program were compared to other analytical predictions and experimental results available in the literature. It was concluded that the proposed analytical model and the computer program predicted bend allowance and springback within acceptable accuracy.