Optimization Of Technological Parameters For Drawing Process Of Wheel Cover Panel Based On Dynaform

As an automobile panel, automobile wheel cover panel has a complex outline, and a large drawing depth, so some defects, such as cracking, wrinkling, will frequently occurred during the the forming process, and the optimal combination of forming process parameters can’t be simply obtained by experience. So it is necessary to optimize and design these parameters of the forming process. Applying CAE simulation technology for drawing technology and die of automobile panel to do numerical simulation and a large number of technological parameters and combination can be optimized, and can preliminary estimate the feasibility of forming. What’s more, it can also reduce the risk of drawing technology and dies design errors, and the die design and manufacture cycle can be shortened and the costs can be reduced.Based on sheet metal forming elastic-plastic theory and the CAE software Dynaform, the drawing process of automobile wheel cover parts was investigated by the finite element numerical simulation, so that technological parameters for drawing process can be optimized. By using orthogonal experimental design, this paper investigates following parameters: blank holder force, punch velocity, die clearance, friction coefficient, draw bead resistance, which influence the forming quality of wheel cover. Considering maximum thinning rates and wrinkling rates as evaluation index, and designing three kinds of weightings about maximum thinning rates and wrinkling rates which are q1, q2, q3, and obtaining a comprehensive evaluation of the results which are Q1, Q2, Q3. Next, the rule and influence mechanism of process parameters on on defects such as rupture and wrinkling are analyzed to obtain a better technological parameter combination. And then, choosing the main influencing factor of first time orthogonal experiment such as blank-holder force, die clearance, drawbead resistance to do another orthogonal experiment, which investigating and optimizing the process parameters, and getting a more optimal combination of process parameters. Finally, in order to obtain meaningful drawbead structure parameters, it’s important to choose drawbead geometrical size, such as convex rib radius, groove radius, height of drawbead according to the optimized drawbead resistance and normal force, and to do orthogonal experiment, which investigates influence of the drawbead geometrical size to drawbead resistance and normal force, and inverse designs the better parameters of drawbead geometrical size.The investigation results show that when the weight of maximum thinning is 0.75 and the weight of wrinkling is 0.25, the optimization technological parameters is that blank-holder force is 300 kN, punch velocity is 3000 mm/s, die clearance is 1.33 mm, friction coefficient is 0.18, draw bead BD1 and BD2 percentage is 23%; by using these technological parameters to do numerical simulation, part’s thinning rate is 28.226%, wrinkling rate is 9.131%, and obviously all the effective parts are in the security area of the forming limit diagram(FLD), and the these parts don’t crack and wrinkle, so the forming effect is good. With drawbead percentage is 23%, equals meaningful structural parameters of drawbead is that convex rib radius is 4.5 mm, groove radius is 4.8 mm, and draw bead height is 4.9 mm. The optimization of process parameters and drawbead geometrical size for drawing process technology and die design of a certain automobile wheel cover panel has a guiding significance.