Analysis And Optimization Research On Forming Process Of WL Passenger Car Rear Floor

The car rear floor is one of the chassis parts,which mainly plays a supporting role for the car and the personnel.At the same time,it forms the main part of the car chassis together with the front floor,so the car rear floor must ensure a good degree of assembly with the front floor and sufficient rigidity^[1].therefore,the formation quality requirements for the car rear floor are also higher.In this paper,the above-mentioned forming defects appear in the car rear floor of a certain brand of automobile produced by a certain company.The finite element software is used to simulate the car rear floor forming process and the post-processing results are analyzed.It is found that the car rear floor has defects such as cracking,wrinkling,insufficient forming,etc during drawing forming.and at the same time,in the process of flanging of the rear floor,a stacking defect occurs at the flange of the convex curve.In view of the cracking,wrinkling and insufficient forming defects of the car rear floor during the drawing process,the drawbeads are re-arranged,and the drawing forming process parameters are designed and optimized,In view of the stacking materials appearing in the process of flanging of the car rear floor.Firstly,the basic research on the convex curve flange and the process incision was carried out,which provided a theoretical basis for the enterprise to open the process incision.Then,based on the above research,the car rear floor flanged stacking area was optimized.Based on the above content,the following aspects are mainly studied:?1?Firstly,the structural characteristics of the car rear floor of the passenger car are analyzed,and the process supplement design,process design and sheet size optimization are carried out according to the characteristics of the rear floor structure;?2?The car rear floor forming finite element model was established by using the enterprise experience parameters,and the obtained rear floor post-treatment results were consistent with the cracking,wrinkling and insufficient forming in the actual production of the company.The forming limit diagram and thickness distribution map of the rear floor were analyzed,and the drawbeads were re-arranged and optimized for the insufficient forming phenomenon.The forming limit diagram and thickness distribution map when the drawbeads were present were analyzed and compared.?3?In order to characterize the cracking and insufficient forming defects in the car rear floor drawing process,the maximum thinning rate and the safety area area objective function were constructed respectively.The drag coefficient of drawbead 1,the drag coefficient of drawbead 2,the drag coefficient of drawbead 3 and the blanking force are optimized variables,and the central composite experimental design method is adopted.In the scheme design,the response surface function model of the maximum thinning rate and the area of the safe area in the car rear floor drawing forming process was established.The multi-objective optimization of process parameters is carried out by using the constructed response surface function model,and finally a set of comprehensive optimal process schemes is obtained:drawbead 1 drag coefficient A=0.50,drawbead 2 drag coefficient B=0.55,drawbead 3 drag coefficient C=0.60 and the blanking force D=140T,and the finite element simulation of the optimal process scheme is carried out.The simulation results show that the cracking of the sidewall of the rear floor boss and the wrinkling of the upper part of the boss are solved,and insufficient forming is significantly improved.The actual process after verification is actually produced,and qualified rear floor parts are obtained;?4?For the problem of the stacking of the rear floor in the flanging,firstly,the forming relationship between the forming curve of the convex curve and the flanging member is studied,and then the influence degree of the different kinds of process incision on the flanging stack and the influence of geometric parameters of U-shaped process incision on the flanging stack are studied.Finally,based on the above research,the area of the rear floor flanging stack was optimized.