Research On Key Technology Of Automobile Body Stamping Sharp Edge

The sharp edge features of car body are more and more popular with markets and consumers.The sharp edge design can divide the surface,reduce the heavy appearance of the car body,and significantly improve the dynamic,delicate and delicate appearance.At the same time,it also puts forward higher requirements for the technical level of car body manufacturing enterprises.The outer panel directly constitutes the outer surface of the car,any small surface defects in the light tunnel inspection,the formation of irregular diffuse light and shadow stripes will seriously affect the appearance of the car.Therefore,according to the actual production needs,this paper explores the control of skid line defects and springback problems in the process of body sharp edge stamping,in order to improve the manufacturing accuracy and surface quality of the final product.In this paper,the mechanical analysis of the material passing through the edge line fillet area is carried out.It is found that the skid line defect caused by uneven thinning of sheet metal is mainly related to the diameter thickness ratio and in-plane tension,which proves the theoretical basis of the compression process for relieving springback.With the help of finite element analysis,the sharp edge model of stamping is established,and two indexes for evaluating skid line defects are proposed,the peak value of thickness gradient and the offset distance of skid line.On the premise of meeting the forming quality of automobile outer panel,the influence of diameter thickness ratio,edge angle and blank holder force on the peak value of thickness gradient and offset distance of slip line is explored;considering the fluctuation of material parameters and the common use of aluminum alloy and high strength steel,the effects of strength coefficient,yield strength,thickness anisotropy,elastic modulus and Poisson's ratio on skid line defects are studied.Taking the fender as an example,this paper expounds the typical stamping process design with the requirements of edge sharpening,including the selection of stamping direction,the design of parting line,and the addendum surface with equal height or elevation at both ends of edge.Considering the defect of skid line,the sharpening scheme of fender shoulder line is determined according to Audit evaluation standard.Based on the strength analysis method of load mapping,the influence of elastic mold on springback and skid line defects of fender was studied.The elastic deformation of the press and mold structure was optimized and compensated iteratively,and the die surface refinement scheme of the fender drawing mold was determined.The effectiveness and feasibility of the stamping process and the die surface refinement design were verified by means of the blue oil coloring effect,the Audit review results of the drawing process parts and the 3D scanning point cloud data.