Research On The Hydraulic Bulging Process And Failure Control Of Complex Curvature Parts Based On Aluminum Alloy 2B06

Aerospace and automobile products mainly meet the requirements of light weighting through structural optimization,adoption of new materials and new forming processes.Aluminum alloys are lightweight materials and have the most applications in aviation.However,the forming performance of aluminum alloy is poor at room temperature,and the precision requirements of aerospace parts are very high,the traditional forming process cannot meet these requirements.Therefore,sheet hydroforming has been applied more and more in the aviation field.The aluminum alloy aerospace parts mostly have complex curved surfaces,in which the local small fillet features are prone to rupture and poor mold matching during the forming process,which limits the application of advanced hydroforming techniques.Therefore,this paper study the small fillet filling of complex curvature parts based on the aluminum alloy 2B06 during the forming process,the failure of the small fillets is controlled through the optimization of process parameters.Firstly,the influencing factors in the forming process of small fillets are determined:friction coefficient,blank holder force,free bulging height,liquid chamber pressure,etc.Several different types of lubricating media are selected;the blank holder force and the relationship between the hydraulic pressure and the fillet radius during the forming process are calculated;different free bulging heights are set;and the mold profile is designed to a complex surface with center small fillet characteristics,large curvature characteristics,and bottom tip features to facilitate the study of the free filling process of small characteristics.The DYNAFORM/LS-DYNA software was used to numerically simulate the hydroforming of complex curvature parts.The pressure of the liquid chamber is determined by the fracture experiment of the maximum free bulging height.The wall thickness and stress distribution of the parts,and the part-mold contact gap distribution of each characteristics under different free bulging heights were analyzed.The springback law of large curvature characteristics and the influence of hydraulic pressure on the deformation of small fillet characteristics were also studied.The numerical and experimental methods were used to the sheet hydraulic bulging test under different friction coefficient,blank holder force and free bulging height.The effects of different process parameters on the forming limit and the limit radius of the parts were studied.The material flow characteristics of various parts of the part under different process parameters were analyzed,and the deformation law with the change of hydraulic pressure of each characteristic of the parts are analyzed.Designed a set of molds to realize the adjustment of different free bulging heights.The sheet hydraulic bulging test is carried out to obtain the distribution law of the part-mold contact gap and the wall thickness under different process parameters,and the correctness of the simulation results is verified.According to the simulation results,the optimized process parameters were set to form a part with a good surface quality and a small local fillet radius.Through the optimization of the process parameters,the fracture and the poor mold matching of the small fillet were controlled.