Analysis On The Drawing Springback Of Automobile Rear Floor Parts

Sheet metal stamping is a widely applied plastic forming technology.Numerical simulation has been used to aid stamping process design,die engineering and problem solving.However,with further and deeper application,the limitations of the current simulation technology surfaced up,namely,it cannot accurately or even correctly calculate the springback under complex stamping environment.The proposed project aims to establish the finite element model for stamping simulation of large drawn panels with drawbead,and to develop an automatic switching scheme between dynamic explicit algorithm and static implicit algorithm during springback calculation.These methods will help accurately calculate the springback of automobile rear floor parts.First,some key issues in finite element simulation,such as finite element solving methods,material models,element types,finite element grid divisions,and real drawbead models,are discussed in detail.And the evaluation standards of forming quality and springback of the automobile rear floor parts are introduced.The numerical simulation model and springback calculation method based on DYNAFORM for stamping forming of automotive rear floor parts are built.Second,DYNAFORM is used in finite analysis of the automobile rear floor parts,the in-plane anisotropic yield and isotropic hardening criteria are taken as the materials type,the influence of blank initial mesh size,element type,stamping speed,blank holder gap,blank holder force,number of integration points on automobile rear floor parts forming and springback are studied,to observe whether the springback direction is correct.The results showed that under the premise of MAT36,applying the blank holder control methods with the equal thickness blank holder gap,the springback direction can’t be calculated accurately by changing the blank initial mesh size,element type and stamping speed.But when the blank holder gap is 1.1 times of blank thickness,the springback direction of the rear floor parts can be calculated accurately.Furthermore,the springback direction can be calculated by exerting a reasonable blank holder force when the force control blank holder is applied.Under the premise of the correct calculation of the springback direction,the precision of springback calculation can’t be improved obviously but the simulation cost is increased greatly by increasing the number of integration points.Finally,the MAT226 that can reflects the Bauschinger effect was taken in this simulation to improve the accuracy of springback calculation.The results showed that the blank holder control methods with the equal thickness blank holder gap and force control blank holder can guarantee the accuracy of the springback direction,and the simulation results with MAT226 are more rational than that with MAT36.In addition,the calculation with force control blank holder is superior to the blank holder control methods with the equal thickness blank holder gap,which can be concluded with MAT226 and MAT36.At the same time,it is proved that the parameter setting in this paper is feasible to analyze the spingback of automobile rear floor parts.