Research on iterative compensation method for springback control based on implicit equation

The parameter solving method for springback control mainly depends on theoretical models and numerical simulation. However, many assumptions are adopted in the theoretical model, which inevitably lead to prediction error in practical application. Therefore, for bending and straightening process, a difference iterative compensation method and secant iterative compensation method based on the implicit equation were proposed. In these methods, the deflection and curvature were taken as the control parameter of iterative compensation, and the convergence of deflection was also verified by theory. According to the proposed iterative compensation strategy, an automatic straightening equipment was developed. On this basis, the bending and straightening of shafts and stretch-bending experiments were carried out to demonstrate the efficiency and reliability of the proposed iterative compensation strategy. The results show that the iterative compensation methods can predict the next compensation value based on the springback value of each tests, so that the target value with the error of less than 2% can be obtained with 2–3 iterations. Moreover, the proposed methods are independent on the material properties and mechanical model, and has high convergence precision for the springback compensation problem.