Optimization Design For Stamping Process And Springback Compensation Of Automobile Front Door Outer Panel

In recent years,China's auto industry has been developing continuously,and automobile production and sales have been growing at a high speed.Meanwhile,the competition is also increasing.During the development of new models,the surface quality and dimensional accuracy of automobile panel are demanding and defects are easily occur in the process of stamping.Combining the constantly growing CAD/CAE technology with the advanced optimization methods,it can effectively improve the comprehensive forming quality of the automobile panel,shorten the development cycle,push the new models to the market faster,and improve the competitiveness of the automobile manufacturers.In this paper,the front door outer panel is chosen as research object.Some key problems such as finite element numerical simulation,multi-objective optimization design and springback compensation technology in the whole stamping process of automobile panel are studied with the help of CAD/CAE technology.Firstly,according to 3D model of the parts and the principles of process design,the stamping process was reasonably arranged.Through the combination of CATIA and AutoForm,the finite element models of drawing,trimming and piercing,flanging process were established and the numerical simulation of the whole process was carried out for the stamping of the parts.For the drawing process,the influence of different drawing surfaces and binders on drawing thinning rate was mainly studied.And the reasonable drawing surface and the better drawing formability were obtained.For the trimming and piercing process,the problem of piercing angles was mainly solved.For the flanging process,the flanging surface and flanging angles were designed.The numerical simulation results showed that the formability for drawing and flanging process of the parts was good,but the springback was overall large after trimming.Secondly,in order to further reduce the maximum thinning rate of drawing and make sure the springback after the trimming as small as possible,taking the drawing circle radius,drawbead line force,friction coefficient,blank holder force,stamping speed as the process parameter variables,and the maximum thinning rate of drawing and the maximum springback after trimming as the optimization objectives,orthogonal test of five factors and four levels was designed.The range analysis and variance analysis were used to deal with the experimental data and the effect of each factor on the maximum thinning rate of drawing and the maximum springback after trimming was analyzed.Then the optimum combination of process parameters for each single objective was obtained.The grey relational analysis method was adopted to calculate the correlation coefficient and correlation degree of each process parameter to the objective function,and optimal combination of process parameters for multi-objective optimization was obtained.The optimized drawing process parameters was used to simulate again in AutoForm.The simulation results show that the maximum springback after trimming was reduced while the maximum thinning rate of drawing was satisfied.Finally,on the basis of the process parameters after multi-objective optimization,in order to further control the springback of the parts within the tolerance,the springback compensation for the drawing surface was made through AutoForm,making the springback after trimming of the parts was controlled within 0.5mm.Based on the compensated drawing surface,the springback compensation for the surface of flanging process was carried out,making the final springback after flanging of the parts was controlled within 0.5mm.The surfaces after springback compensation were used for mold processing and trial production.The surface quality and dimensional accuracy of the part meet the requirements.