Impact of pressure die on springback and section deformation of rotary-draw bending of rectangular H96 tube

In order to control springback and section deformation of rotary-draw bending of rectangular tube, the finite element model for springback and sectional deformation prediction, which considers the loading and velocity conditions of pressure die, was established and verified by experiment. Based on the model, the impact of friction coefficient, pressure and boosting velocity of pressure die on springback and section deformation of H96 rectangular tube was investigated. The results show that the larger the friction coefficient and the clamping pressure are, the smaller the springback angle and the cross-section height deformation are. However, the impacts of pressure die on deformations of cross-section and longitudinal-section are completely opposite. The change of boosting velocity within core-filled area can influence the springback amount, while not exacerbate section deformation at the same time. Then, the combinations of pressure die boundary conditions of variable boosting speed were proposed. And by which, it is realized that springback angles are decreased by 55.31% and 36.45%, respectively, for bent tubes smaller than 90° or no less than 90°. The cross-section height deformations are reduced by 1.79% for 60° tube on average, and 5.98% and 6.35%, respectively, for 90° tube and 120° tube at most.