Foreign progress in numerical simulation of sand casting

The research field of Solidification Numerical Simulation of sand castings abroad started early, which began in the 1960s. Its development process can be roughly divided into the following three stages:

1) In the basic research stage, it focuses on the numerical simulation of the temperature field distribution of sand castings;

2) In the prediction research stage, the sand casting defects are predicted by checking the sand casting process plan after completion; Through the simulation of flow field, the revision of pouring scheme is completed with the help of computer, and the research on the simulation of microstructure has also begun;

3) Optimize the process design stage, including calculation simulation, geometric simulation and database establishment, and effectively combine them.

In the 60s of last century, the Danish people applied the finite difference method to study the numerical simulation of solidification process, which opened up a new world for solidification simulation. Three years later, GM applied the general program of transient heat transfer to simulate the sand casting of automobile cylinder block, which was verified by the actual measurement of sand casting. Subsequently, American universities began to carry out planned research in this field. Based on the discrete Fourier equation, the mathematical model is established by using the explicit difference method, alternating implicit difference and finite difference scheme. The calculated temperature value is compared with the measured temperature value, and the isochron and isotherm distribution map of temperature field are obtained.

After the 1970s, following the United States, the former Soviet Union, Canada, Japan and other countries have also carried out relevant research and published a large number of influential articles. For example, Dazhong Yixiong of Osaka University in Japan proposed the direct difference method in view of the weakness of the finite difference method; Japan’s shinyama Yingfu proposed the pseudo three-dimensional calculation method and the prediction criteria of shrinkage and porosity. These scientific research achievements have laid a good foundation for the subsequent scientific research work of various countries.

In the 1980s, solidification numerical simulation research has formed a worldwide upsurge. The American company developed the three-dimensional temperature field simulation software by using the finite difference method, and simulated the solidification process of large cast steel roll. The baccas software developed by Kawasaki iron making Institute of Japan simulated the solidification process of shell precision casting, and successfully predicted the generation of shrinkage cavity; T. Inoue et al. Explored the viscoelastic plastic constitutive relationship of materials; G. L. dymove et al. Carried out simulation research on three constitutive relations: elasticity, viscoelasticity and elastoplasticity. Many simulation software have been combined with the actual production process and began to enter the practical stage.

Since the 1990s, the development of three-dimensional numerical simulation software has become more and more perfect. Many commercial software have been applied in practical production with good results. Such as MAGMAsoft in Germany, ProCAST in the United States, CastCAE in Finland, etc. Y. Otsuka of Japan used the finite element method to simulate the residual stress distribution of gray cast iron cylinder during sand casting, and the simulation results are consistent with the actual measurement; A. I. manesh simulated the solidification stress distribution of continuous steel castings; P.R. Sahm of Germany used the finite element software Casta to simulate the residual stress distribution of machine tool worktable under different reinforcement forms. These simulation software can simulate the temperature field, flow field and stress field, and predict the defect location and the tissue distribution of each location. Numerical simulation is beginning to develop to investment molding, low pressure casting and continuous casting.