Research On Hydroforming Process Of Special-shaped Aluminum Alloy Parts Based On Numerical Simulation

With the gradual deepening of the development concept of lightweight,energy saving and emission reduction,lightweight materials such as aluminum alloys have been widely used in the manufacturing industry.Aluminum alloy sheets are widely used in the automotive industry and have become the main application materials in the automotive body in white.However,for parts with complex structures and shapes,aluminum alloy plates have poor forming effects and low product qualification rates.Parts with complex structures have always been a difficult point in the study of sheet metal forming.To improve the formability of parts with complex structures,this paper takes 6061-T6 special-shaped aluminum alloy parts as the research objects,and combined with numerical simulation and experiment to analyze the formability of the special-shaped aluminum alloy part.In view of the particularity of the structure of the convex-concave specialshaped aluminum alloy parts,this paper proposes a method of pre-bulging forming and then deep drawing with hydroforming.The advantage of this forming method is that not only can the bottom of the part be formed by the pre-bulging pressure,but also the blank can be bonded to the bottom of punch under the action of the prebulging pressure.Before the deep drawing,reduce the hanging of the blank at the side wall step and increase the contact area between the blank and the punch,so that the parts deform uniformly under the interaction of the punching force and hydraulic pressure,and the forming effect of the parts is better.The influence of the pre-bulging process on the forming limit diagram,wall thickness distribution and fittability of convex-concave special-shaped aluminum alloy cylinder was studied,and it was concluded that increasing the pre-bulging height or the pre-bulging pressure alone increases the risk of wrinkling and cracking defects.Reasonable selection of the combination of pre-bulging height and prebulging pressure,sheet forming effect was better.By setting different blank holder force,blank holder gap and liquid chamber loading pressures,the forming defect law and wall thickness distribution of the blank under different parameters were analyzed,and the reasonable forming parameters were obtained.Combined with the simulation analysis law of convex-concave special-shaped aluminum alloy parts,this paper were carried out by numerical simulation and experiment.Taking the forming limit diagram and wall thickness distribution diagram of the parts as reference,the deformation law and wall distribution law of the convex-concave special-shaped automobile sunroof panel under different forming parameters were analyzed,and the optimal forming process parameters were obtained.The experimental verification was carried out under this parameter,and the experimental results were consistent with the simulation results,which met the expected goal.