Study On Fine Simulation And Optimization Techniques For Auto Panel Forming Processes

With the rapid development of the China automobile industry, the technology of numerical simulation for sheet metal forming of auto panel has been widely used to predict product forming defects in early design stage and improve the quality of the process and structure of die design. The simulation technology is still under development to meet the requirements of the higher simulation accuracy at the design and field test stages. Therefore, it is very important to research the subject about the refinement of simulation and optimization techniques of auto panel.The study is supported by the fund of the National numerical control major projects (project name "high-strength steel cool stamping technology research", project No:,2010ZX04014-072). Firstly, both the factors that affect the forming simulation accuracy of auto panel and the optimization technology are analyzed. Then the refinement simulation techniques are studied, which includes the following aspects:In order to study the law of the drawbead resistance and lifting force variation with the high-strength steel und the die structures, the test program is developed. In the program, the drawbeads with the symmetrical and asymmetrical shapes are considered. The results show that:The variation laws are same in the symmetrical and asymmetrical shapes drawbead with common steel. But the laws are different with the high strength steel. The geometric parameters with asymmetrical shape drawbead will affect the deformation and springback to some extent.Basis on the experiments and simulation analysis, a control method for high-strength steel forming quality with asymmetrical shape drawbead is developed, which can reduce the curl amount of deformation and springback of high-strength steel with less workload and shorten debug time.The drawbead optimization method with knowledge using the incremental finite element method is developed. Firstly, the key features of auto cover is classified to build the drawbead optimization knowledge base. Then optimization method is developed using the Forming Limit Diagram (FLD) as the objective function. In the method, the factors for forming formability, such as, severe thinning, rupture, wrinkling, unsufficient forming within the region of open line are considered, with can solve the problem of the initial value and the long time optimization effectively.The Influencing factor for forming formability of the blank holder deformation is analyzed with the elasticity finite element method. A process optimization and simulation technology is developed to control the gap (Referred as the management face) between the blank holder and the forming sheet. Both the calculation model of height difference within the management face and the setting rules of inner-outer blank holder force are developed using the theoretical derivation and simulation technology.Basis of the simulation results and experimental data, the process parameters for forming formability, such as, the equivalent and real shape drawbead, the blank holder deformation and the gap between blank holder and forming sheet are studied. The conclusions with test and simulation to improve the refine simulation accuracy of auto panel is Significance.