Plastic-formation analysis and springback calculating of thin-wall tube pure-bending

Springback is one of usual quality defects in NC bending process of thin-wall tube.Based on the force analysis for a small volume element of bending tube,the differential equation of force balance on circumference direction and the stress function along the span angle of cross section are built.The position of neutral layer and bending moment are derived,and the springback angle based on principle of virtual work can be deduced.The NC bending experiments of thin wall tube with different geometry parameters are finished,and the theory prediction model is proved accordant with the experiment results.Finally the rule of springback angle affected by the bending angle and relative bending radius is analyzed.Springback compensation can be calculated before bending to improve the formation precision of tube bending.