Research On Structural Design And Vacuum Die Casting Process Of Aluminum Alloy Shock Tower

With the continuous implementation of the national energy conservation and emission reduction policy,the new energy vehicle will become the development trend of the automotive industry in the future,and the lightweight demand for automotive structure is also improving.The current direction of automobile lightweight research is mainly for lightweight design,research on new lightweight materials and advanced manufacturing technology.A new energy automobile aluminum shock tower of JAC was designed to take the place of the original steel structure,it provides a new idea for the lightweight design of large and complex thin-walled die castings,and it is of great theoretical and practical significance to the light weight of automotive parts.In this paper,theory of structure optimization design and casting simulation were introduced,we conducted a comprehensive study of the structure and process of die casting,design principles such as radius and stiffener arrangement were investigated with reference to the design manual of die casting,the principle of the choice of wall thickness and gate location were given,design principle for die casting structure was thus improved and it would provide the basis for the structure and process design of the shock tower.Based on the JAC model,structure design method of large thin-wall die casting with stiffeners inside was summarized: static analysis was applied to the original steel structure to extract performance such as structural strength and stiffness requirements,which would serve as constraint conditions in the process of topology optimization.Topology optimization was implemented to determine the overall structure of shock tower and the distribution of the reinforcement,then,size optimization was applied to determine the thickness of the stiffeners to obtain the final design.In the process of optimization by HyperWorks-Optistruct,influence of different optimization space design ando draft partition constraints,manufacturing constraints such as the maximum and minimum size of different members on the optimization results was invistigated.Different gating system were designed for the aluminum shock tower,gating system structure with multi-gate was determined by the comparison of the filling and solidification process in the ProCAST,furthermore,the process parameter was optimized by orthogonal test,the optimum process parameters are as follows: preheating temperature at 200℃,casting mould at temperature of 200 ℃,the vacuum degree is 5KPa and the injection speed is 3.0m/s.Actual production experiment was implemented according to the simulation results,the performance obtained by two kinds of mould casting structure was compared to verify the reliability of simulation results,vacuum die-casting with good mechanical properties through the gating system structure and optimized process parameters,the average mechanical properties of the test points of the shock tower castings after heat treatment are as follows: yield strength is 261 MPa,tensile strength is 315 MPa and the elongation is 9.4%.