Numerical Simulation Of A356 Aluminum Alloy Cylinder Head And Prediction Of The Effect Of Casting System Structure On The Quality Of Castings

At present,the casting research of complex thin-wall castings is more extensive,mainly concentrated in aerospace,automotive and other fields.The demand for aluminum alloy castings is increasing day by day,and the precision and performance requirements are higher and higher.The main hidden problem in castings is in the aspect of defects(shrinkage loosening and shrinkage holes).In this paper,the casting shrinkage porosity and porosity technology is combined with casting molding.Taking A356 engine cylinder head as the object,the method of theoretical research and numerical analysis is used to analyze the quality problems in the casting process,explore the influence of process and structural parameters on the shrinkage porosity and porosity defects and casting cycle in the filling and solidification process,and carry out multi-objective optimization design of the casting system.The main work and conclusions of this paper are as follows:(1)The control equations and models are used as the basis and the solution method is used as a guide to prepare the theory for the filling and solidification study of castings.To explain and analyze the prediction principles of defects such as shrinkage loosening and shrinkage holes generated during the filling and solidification process,and to investigate the evolution and causes of defects in castings.(2)Establishing the structure of casting’s casting system.The geometric model of the casting was established using 3D software,and the geometric model of the casting system was established according to the structural characteristics of the casting and the design principles.Numerical simulation analysis of the casting was carried out using CAE to determine the relevant characteristics of the casting and casting material,mesh irrelevance verification and boundary parameters.(3)The Procast software was used to simulate the filling and solidification of castings.Turbulence model and particle tracking model are used to track the flow velocity of metal liquid to explore the flow capacity of metal liquid and track the surface oxidation of castings by releasing particles with the same metal properties.The heat transfer and solidification properties of castings were investigated by the solidification heat transfer model,and the location distribution and size of shrinkage porosity and porosity after liquid solidification were predicted by the shrinkage porosity and porosity model.By analyzing the shrinkage porosity and solidification time of castings with different parameters,the influences of different factors on casting quality and casting cycle were explored.(4)Multi-objective collaborative optimization design of gating system structure was carried out based on multi-objective optimization method.By establishing the response surface model between the variable and the target,the algorithm and TOPSIS decision method are used to select the optimal parameters.The results show that the error is small after numerical verification.The optimal shrinkage volume and solidification time are8.75cm3 and 119.71 s,respectively.Compared with the original design scheme,the optimized shrinkage volume and solidification time are reduced by 9.80% and 7.25%.