Research On Prediction And Control Of Bending Springback

Bending, one of the most common methods in the metal forming, is widely used by the automobiles industry. Many stamping parts, for instance, carlines, cross rails and inner/outer plates etc. are mainly produced by bending. However, springback as an inevitable phenomenon will come out, which is caused by elastic recovery and residual stress after sheet metal bending forming. It affects the quality of forming product directly, including the appearance quality, the assembly course and the final product performance. Otherwise, springback is still a problem to control successfully by now.So, the current researches on springback prediction, measure, control and compensation are going on today. It is significant to investigate how to find out springback laws and values, and how to determine the structure of dies and select the stamping forming parameters and so on before designing moulds, which can reduce and control springback in sheet metal stamping processes. The combination of numerical simulation and experiment is applied to investigate the springback rule of the U&V-shape part, providing a reference to the practical manufacture.The main contents of this dissertation are as follows:1. Key techniques of sheet metal forming and springback simulation are expounded such as finite element method, element type and mesh generation method, selection of element formula, contact algorithm and friction model, material model, springback simulation method. Furthermore, the modeling approach of springback numerical simulation is presented.2. The deformation process and springback of bending are discussed detailedly. A series of springback numerical simulation experiments of U&V-shaped part are carried out. The factors influencing sheet springback are analyzed in this paper, which include bending angle, r/t, bending force, and die gap etc. Drawing the project curve between these factors and springback amount and summarizing a constructive conclusion.3. Designing mould. It will prove that the result from real bending process experiment is close to the one from numerical simulation between the tolerances allowed. So, continuing research on springback by numerical simulation instead of experiment can reduce the expense. Otherwise, this combinative method is realistically more useful and convictive.4. Last, it introduces some ways to control the springback. And the die surface compensation method which is used to control the springback is preliminarily studied. In view of the practical application of U-shape blank, its springback is controlled by using die surface compensation method. The results show that the die surface compensation method which is used to control the springback is practicable.