An Iterative Compensation Algorithm for Springback Control in Plane Deformation and Its Application

Abstract

In order to solve the springback problem in sheet metal forming, the trial and error method is a widely used method in the factory, which is time-consuming and costly for its non-direction and non-quantitative. Finite element simulation is an effective method to predict the springback of complex shape parts, but its precision is sensitive to the simulation model, particularly material model and boundary conditions. In this paper, the simple iterative method is introduced to establish the iterative compensation algorithm, and the convergence criterion of iterative parameters is put forward. In addition, the new algorithm is applied to the V-free bending and stretch-bending processes, and the convergence of curvature and bending angle is proved theoretically and verified experimentally. At the same time, the iterative compensation experiments for plane bending show that, the new method can predict the next compensation value based on the springback of each test, so that the target bending angle with the error of less than ± 0.1% and the target curvature with the error of less than 0.5% are obtained after 2-3 iterations. This research proposes a new iterative compensation algorithm to predict springback in sheet metal forming process, where each compensation value depends only on the iteration parameter difference before and after springback for the same forming process of same material.

A Method for Simultaneous Optimization of Blank Shape and Forming Tool Geometry in Sheet Metal Forming Simulations

“…Edge Deviations Location (mm) Location (mm) 2 illustrates that the measured deviations are below the required values. It should be noted that the predicted values generally follow the measured ones, with few exceptions (e.g., surface points 3,5,6,12), where the measured deviation is greater than the predicted one. In both cases, however, the improvement in the product geometry is not as large as predicted by the optimization procedure and corresponding computer simulations.…”

“…The adjustment is performed iteratively, where the tool geometry compensation is applied in the direction parallel to the punch travel. While the method is simple and relatively straightforward, several improvements have been proposedrecently, for example, by Ma et al [12]. One of the first improvements was proposed by Lingbeek et al [13] to resolve the issue of different topological structures of tool and blank geometry by using smooth surfaces.…”

Research on Springback Control in Stretch Bending Based on Iterative Compensation Method

“…It can be concluded that if the equation f(x) � a needs to be solved iteratively, 0 < f ′ (x) < 1 is an indispensable condition. According to the equivalent stress-strain relationship in the elastic-plastic deformation shown in Figure 1 [20], the springback ε 2 e produced by the larger equivalent strain ε 2 is distinctly greater than the springback ε 1 e produced by the equivalent strain ε 1 . erefore, for the same ordinary metal materials, the larger the deformation, the greater is the springback when maintaining deformation conditions.…”

“…e following basic assumptions are made in the mechanical model. First, the cross section is Figure 1: Equivalent stress-strain curve in elastic-plastic deformation and springback process [20]. Mathematical Problems in Engineering assumed to be always planar and perpendicular to the neutral layer.…”

“…Although the above methods can quickly meet the requirements, they need either the specific material properties to establish mechanical models or a large number of finiteelement simulations. Ma et al [20] established an iterative compensation mechanism based on an iterative solution method, but they only analyzed pure bending under a simple stress state. A clear and stable compensation direction has a great effect on the precision of the results.…”