Optimization Analysis On Initial Sheet Metal Contour Line Of High Strength Boron Steel In Hot Stamping

Cars come into the common households as a symbol of convenience, high speed andfashion, enriching people’s lives since the new century. However, the rapid developmentof the auto industry has also brought some social problems. For example, combustion offuel accelerates energy consumption, automobile exhaust emissions cause air pollution,which have seriously affected people’s health and also have brought a series of safetyproblems. In face of such situation at that time, the concept of lightweight automobile hasbeen proposed and gradually been accepted. Therefore, hot stamping technology and itsnumerical simulation technology emerge as the times require.In the process of hot stamping forming, sheet metal of high strength steel is heat toaustenite state, then formed, and parts with homogeneous martensite organization, smallspringback and high strength level at room temperature after cooling will be obtained.Nowadays, hot stamping technology has been applied to the produce of the cross beam,the longitudinal beam，A column, B column, C column and some other components ofcars. Therefore, hot stamping technology is a hot technology for automobile industry.The initial blank shape is an important factor that affects the quality of sheetmetal forming. A reasonable initial sheet metal contour line is beneficial to improvematerial utilization ratio, to reduce defects and to improve the quality and performance ofthe components. For a long time, the initial blank shape of hot stamping is always aresearch focus. Nowadays, people obtain sheet metal contour lines for hot stamping by getting the blank contour line with one step inverse method and expand it about10%,then cut the redundant after stamping. In fact, that wastes raw materials and energysources; also, the production efficiency is low. In order to get the initial blank contour line,a large amount of exploration has been done. This paper simulates the hot stampingforming process and establishes the initial sheet metal contour line optimizationcalculation model based on the multi-step iterative inverse method with sheet metalforming simulation software and finally obtains the optimized initial sheet metal contourlines of high strength boron steel blank. Therefore, a stamping part would beaccomplished with only one forming step which saves materials and the trimmingprocesses. It is an effective guidance for the production with high precision, high qualityand high efficiency. The main research works of this paper are presented as follows:(1) Design a simple U shaped part and get the initial sheet metal contour line withone step inverse method; establish it’s stamping model and the correspondingoptimization model based on hot stamping principle; study impact of blank thickness onthe optimization of initial sheet metal contour line; do experiment with data collectedfrom the optimized initial blank contour line and compare its sizes after stamping withideal U shaped part’s.(2) Establish the hot stamping model for a front bumper beam of an automobile andoptimize the initial blank contour line with multi-step iterative method; compare itsforming precision before and after stamping; analyze the thinning distribution, stress andstrain distribution of the hot stamping part whose contour line has been optimized.(3) Establish the whole and the partial optimization model for a B column of anautomobile and analyze the data, study the influence of blank holder force on the sheetmetal contour line optimization results and put forward reasonable explanations.