| The automobile industry of China has taken shape after several decades'development, the output of automobile increases greatly. The development of Al automobile hub industry is promoted by the fast developing of automobile industry, especially the passenger car industry. Nowadays, Al hub is applied in almost all types of new passenger car. The domestic light alloy hub industry starts relatively late, but develops rapidly. Now China has become a production country of Al automobile hub, while a majority of companies depends mainly on the experiential mode of production, there is a repeated process from mould development to trial production, then modifying mould and process scheme. During the designing process of casting process, there are many complicated calculations and lookup work. Technological design personnel resorts on personal experience and manual operation, which is time consuming, moreover, the results are always with low precision, reliability, unsatisfied casting quality. Repeated experiments also increase the production cost, development cycle and reduce the yield.The effective method for the prior problems is developing advanced casting numerical simulation technology. The whole process of mold filling and solidification of castings can be observed by computer visualization technology to predict and analyze the defect and its position in the cast product, then judge whether the technique is reasonable and the casting structure meets the use requirement. According to the above results, which provide theoretical basis for obtaining cast with less defect and high quality, the casting process and structure can be improved. Meanwhile, the development cycle can shorten, and the production cost decreases, production efficiency improves.We take one type of Al hub for example, simulate the process of mold filling and solidification of castings, predict defect during the process. The main conclusions are as follows:(1) The mould was established using Pro/E in this study. Metal-mould low pressure casting has to use assembly mode because it at least includes metal-mould and casting. Acquiescent Entity format file of Pro/E for assembly is .asm, which is unacceptable by ProCAST, therefore, the data can only be transferred through standard interface format file, which contains dividing surface cell and volume mesh in MeshCAST, dividing surface cell in Pro/E, dividing volume mesh in MeshCAST, dividing surface cell and volume mesh in Pro/E. We found there were some problems when dealing with the casting and mold interfaces by these methods. So it was difficult to form volume mesh. The HyperMesh software was introduced to divide mesh. After testing, it is found that the mesh divided by HyperMesh software can be read-in MeshCAST, and obtain finite element mesh meeting the requirement after units detection.(2) Mould structure has great influence on the process of mold filling. In this study, the liquid metal flow was hindered by the five salient cylinders in the bottom die during the process of molten aluminum filling, which caused different filling speeds of initial liquid metal in seven wheel spokes. This situation was relieved at the intersection of wheel spoke and wheel rim, but the irregularity of metal level was discovered at the late stage of filling. After removing the salient cylinders in the bottom die, the filling process became stable. Therefore, it should ensure unblocked flow channel and avoid structural obstruction when designing mould.(3) The shrinkage porosity was discovered at the intersection of wheel spoke and wheel rim and the central part of hub after the simulating of casting solidification. The shrinkage porosity was attributed to the disconnection of feeding channel for the intersection structure. The isolated liquid can't be compensated by metal liquid during the solidification process, which led to generate of defect. The shrinkage defect can be eliminated by increasing air cooling at corresponding position and improving the cooling speed at the two positions, which proved that the cooling system of low pressure casting played an important role in the realization of sequence solidification.(4) The variation of pressure speed has an obvious effect on the temperature distribution of wheel rim when the pouring temperature is constant. The faster the pressure speed is, the higher the average temperature of wheel rim is, but the change of wheel spoke isn't obvious. The best pressure speed is pouring 0.0017 MPa/s,best pouring temperature is 700℃,in this experiment.
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