Numerical Simulation And Draw Bead Optimization Of Automobile Panels Forming

At present, automotive industry is one of the pillar industries of China’s economy. It involves the mechanical, electronic, material, energy, finance, transportation and other fields. The level of designing research and manufacturing technology directly affect the upgrading of cars, so the design and manufacture of automobile panels are the main parts of cars. The forming processes of automobile panels often appear as cracking, wrinkling and springback defects. The traditional way-repeatedly test is not only time consuming, and also sometimes it even causes mould scrapped, so quality stability of the products can not be guaranteed. With the development of computer technology, numerical simulation technology is widely applied during product quality control check and mould design. It can not only forecast some possible defects of the tensile parts during processing, but also improve the forming process according to the simulation results. CAE softwares reduce the cost of production and shorten the production cycle of products, the quality stability of the products and market competitiveness of the enterprise are greatly improved at the same time.In this paper, the finite element theories which used frequently in sheet metal stamping were discussed systematically. The theories included element algorithm, yield criterion, contact force and friction handling methods etc. Paper analyzed the defects simply which are common phenomenon during sheet metal stamping, and the countermeasures to solve defects also explained. It introduced the automobile panel stamping technology, the process and key points of numerical simulation very briefly. On the basis of them, the forming simulation of a hood was made and results were analyzed.Using DYNAFORM to establish finite element model of a hood based on its CAD model, including punch, die, binder and blank etc. This paper simulated a hood forming in two cases, without loading draw bead and loading part of the draw bead. According to the simulation results, loading draw bead can improve the quality of a part in drawing. Based on drawing analysis and DYNAFORM, the process parameters such as distribution of the draw bead, distance of the draw bead, deepness of the draw bead, lock force of the sheet metal and binder force were researched by the orthogonal experimental design method. These parameters influence on the forming quality and calculation efficiency were analyzed. In the process of simulation, impact on the minimum thickness from high to low is distance of the draw bead, binder force, lock force of the sheet metal, distribution of the draw bead and deepness of the draw bead. The distinction among the various factors effect on the maximum thickness were not obvious. The minimum thickness, maximum thickness, calculation efficiency were respectively considered as optimize goal to optimize the combination of parameters, and the optimal combination of each was tested. There are more than one indexes to measure the quality of forming, just optimize one of them can not achieve the goal to get the high quality part. For the complex automobile panel, there are so many factors to impact form, only depend on the adjustment of a process parameter is very difficult to obtain a ideal result. In this paper, the high quality was considered as optimize goal to optimize the combination of parameters, and the optimal combination was tested. To get the best quality of products, multiple process parameters should be optimized at the same time. The paper discussed the theory of springback, the main factors which could influence springback and the ways to reduce the springback. Using DYNAFORM predicated and analyzed springback of a hood, and put forward measures to reduce springback at last.