Study On Parameters Optimization Of Stamping Process And Springback Compensation For The Hood Outer Panel

In recent years,with the technology import of joint venture brands and the technology accumulation of independent brands,automobile companies both at home and abroad have made great efforts in China's automobile market.The domestic automobile industry has entered a period of booming development.In terms of independent brand automobile companies,the forming quality of automobile panels has played a vital role in R&D,trial production and mass production of new models,and the enhancement in forming quality of automobile panels has exerted significantly practical influence on many aspects such as shortening the R&D and trial production cycle of new models,improving the vehicle quality,and enhancing the market competitiveness.This paper takes hood outer panel of a new SUV model with an independent brand as research object and numerical simulation on multi-process of stamping forming of the part is analyzed.Besides,it also focuses on the multi-objective optimization of forming process parameters and springback compensation for the hood outer panel.At first,the forming process of hood outer panel was analyzed,and the drawing die surface of the hood outer panel was also designed.In addition,the influence of different drawbead arrangement schemes on the forming quality of hood outer panel was emphatically studied,and the justified drawbead arrangement scheme was identified.Furthermore,the numerical simulation on springback after trimming process of hood outer panel was explored,and the simulation result indicates that springback of the part was overall large.Secondly,in order to control excessive thinning and large springback of the hood outer panel,with the forming quality objectives of the maximum thinning rate of drawing part and the maximum springback after trimming,the central composite experiment was designed and the response surface model was built through selecting the blank holder force,stamping speed,the coefficient of friction between die and blank,as well as the coefficient of friction between punch and blank as the process parameter variables.Then,the multi-objective optimization of hood outer panel forming process parameters was performed and the optimal combination of process parameters was also obtained based on genetic algorithm NSGA-II.Subsequently,the optimal combination of process parameters was simulated,and the error between the simulated value and predicted value is in 0.1%,which thus fully validates the accuracy of response surface model.Meanwhile,the uniform thinning,sufficient drawing and greatly reduced springback of the part also validates the feasibility of the combined response surface model and genetic algorithm NSGA-II in the multi-objective optimization of stamping process parameters.Finally,on the basis of the multi-objective optimization,the drawing die surface compensation of the hood outer panel was employed to further control springback.Through five iterations of springback compensation,the maximum springback was controlled within 1.5 mm and satisfactory springback compensation result was achieved utilizing the function of springback compensation in DYNAFORM.Meanwhile,through applying the optimal combination of process parameters and drawing die surface after compensation into subsequent stamping die design and trial production,the forming quality of hood outer panel is well which can meet the accuracy requirements of new model assembly.According to the results,it demonstrates that the integrated application of numerical simulation,multi-objective optimization and springback compensation can effectively improve the forming quality of panels and shorten the R&D and trial production cycle of the vehicle.In addition,this technological approach also provides a theoretical basis and technical support for the trial and mass production of automobile panels for new models of independent brands.