Design And Optimization Of Drawing Process For Automobile Aluminum Alloy Side

Automobile panel stamping is a complex and large deflection deformation process.Stamping process parameters and process plan directly affect the quality of the panel.By using the finite element technology,the defects of sheet metal in the stamping process can be predicted in advance.According to the results of CAE,the process plan and process parameters can be optimized to effectively avoid most of the forming defects and reduce the number of die tests for panel dies,so as to reduce the cost of die production and meet the requirements of improving product quality and production efficiency.In view of the problems such as cracking and wrinkling in the drawing process of aluminum alloy automobile panel,taking the manufacturing aluminum alloy sidewall by an automobile die company as an example,the processability of the parts was analyzed,the process supplement surface was designed according to the characteristics of the parts,the movement mode of the die and the stamping direction of the plate were selected,and the blank holder force in the stamping process was preliminarily calculated and selected,The process parameters such as friction coefficient and die clearance were determined,and the general design principle of draw bead was introduced.The initial simulation and analysis of the panel including gravity simulation,simulation without draw bead and simulation with draw bead were carried out.The primary simulation results show that the main problems of the aluminum alloy side wall are:a large area of crack at the fillet of the B-pillar flange,a crack at the corner of the door opening,insufficient drawing of the lower threshold beam and too large thinning rate at some local points.For the crack of the door opening,three schemes were put forward,locking the inner ring drawing bead,optimizing the R angle of the blank line and reducing the stamping speed.The results of three schemes show that:when the internal parts are not cracked,locking the inner ring draw bead can solve the problem;passivate the R angle of blank line can effectively reduce the situation of door opening cracking,and reduce the stamping speed can also play an auxiliary role in optimizing the door opening cracking.For the insufficient drawing of the lower sill beam,the L9(34)three factors(draw bead height,die clearance and the type of draw bead)three level orthogonal test was designed.The orthogonal test results show that the higher the draw bead height,the smaller the die gap between the convex and concave dies,and the larger the main strain at the lower threshold beam position,the better the problem of the optimal drawing deficiency can be caused.The effect of the optimal drawing deficiency of the double round bead is better,which meets the requirements of the actual parts.The main factors are the type of the draw bead>the bead height>the die gap.In this paper,the final optimal parameter are draw bead height 5mm,die gap 0.4,The double round bead(A2).Based on the mathematical software MATLAB,two process parameters which are blank holder force and stamping speed were optimized.50 groups of sample data were extracted by Latin hypercube sampling method,and the regression equation of data fitting is used as the fitness function of genetic algorithm.42 groups of sample data which are blank holder force and stamping speed were used as input items of training set construction,and the output items are neural network models of thinning rate and major strain,respectively.8 groups of sample data are used as error size between predicted value and actual expected value of detection set.The prediction results of the model are accurate.The optimal blank holder force is 1950KN and the optimal stamping speed is 1700mm/s.After using the optimized scheme to actual make part and die debug,the final forming state of the panel was good.The Argus stress-strain analysis of the panel was carried out with the optical camera.The results show that the predicted risk area is the same as the actual part risk area,and the actual part is basically consistent with the simulation results,which verifies the effectiveness of the simulation software.The actual maximum thinning rate of the final plate is less than 25%,which meets the requirements of the parts.The optimization scheme has certain reference significance for other similar products.