Springback study of RDB of rectangular H96 tube

Abstract

This paper develops a comprehensive further research on the springback of rotary draw bending (RDB) of rectangular H96 tube, based on the review and revise of the previous research work. The effects of process conditions to springback and sectional deformation are studied and compared by using the simulation and the sensitivity analysis mathematical model. The coupling effects between springback and sectional deformation in the bending process are revealed by using the simulation and the theoretical analysis model. The theoretical analysis model of springback angle is established by taking sectional deformation into consideration in term of piecewise functions of sectional shape. Finally, how to control springback under different filler conditions is studied. The accuracy of finite element (FE) simulation has an important impact on this study, thus it is improved from two aspects of FE modeling, i.e. the accurate descriptions of the boundary conditions and the material constitutive model. The material constitutive model considers the varied elastic modulus effect and the Bauschinger effect. Research shows that: (1) the boundary conditions of force loading dies and tube fillers are the main factors influencing springback and sectional deformation; (2) the sectional deformation is more sensitive to process parameters than the springback; (3) the springback has great effect on the decrease of section sagging and longitudinal section ovalization; (4) the amount of springback is increasing as the overall deformation increases; (5) if the tube filler is mandrel-cores die, the optimized parameters combinations of pressure die can be used to reduce both the springback and the sectional deformation.