Springback analysis of numerical control bending of thin-walled tube using numerical-analytic method

Springback has an important influence on the forming quality of numerical control (NC) bending of thin-walled tube. In the paper, using the numerical-analytic method proposed by authors, the springback mechanism and laws of the tube bending have been analyzed. The results show the following: (1) there are two sources of springback, one is from the plastically curved part of the tube, which has an approximate bilinear relation to the bending angle; the other is from the straight portion, which varies like an exponent line with the bending angle. (2) Based on the above features of springback angle, reasonable regression equations between springback angle and bending angle under different conditions can be obtained. (3) The larger the strength factor, or the smaller the relative bending radius or the hardening exponent, the larger the springback angle. The research may serve as a significant guide to accurate prediction and control of springback.