Study On Forming Limit And Springback Of DP780 High-strength Steel Sheet

At present,high strength steel plates are developing rapidly in the automotive industry,but there are often problems such as wrinkling,cracking and springback in stamping forming.Based on a series of problems in the stamping process,this paper selects DP780 high strength steel as the research object,and obtains its basic mechanical property parameters through static tensile test at room temperature.The main research content is summarized as follows.(1)In order to determine the damage parameters of the GTN model,the influence of three main damage parameters on the forming limit curve was analyzed.After the damage parameters were determined,the numerical simulation was carried out using ABAQUS software,and the forming limit curve was obtained.The theoretical prediction formula of the forming limit curve of DP780 steel was also obtained.The results of experiment,simulation and theoretical comparison prove that both numerical simulation and theoretical formula can accurately predict the forming limit curve of DP780 steel plate.(2)Under the condition that the steel plate is not cracked,that is,when the deformation is below the forming limit curve,the typical U-shaped parts are first analyzed for springback in stamping.The influence of single factor friction coefficient,blank holder force,stamping speed and concave convex die clearance process parameters on springback in U-shaped bending is studied respectively,and the influence of different value parameters on springback is summarized.(3)Under this rule,it is applied to the stamping springback of the automobile anticollision beam.The orthogonal test table of three levels and four factors is designed by orthogonal test,and the influence of three process parameters,namely friction coefficient,stamping speed and concave convex die clearance,on springback is analyzed by range.The optimal parameter combination is obtained.The springback results obtained after springback compensation meet the requirements and the forming quality of stamping parts is good.It provides theoretical reference for the actual anti-collision beam stamping production process.