Development of casting process simulation technology

As early as 1940, when computer technology was just starting, Victor Paschkis of Columbia University of the United States put forward a mathematical model for the analysis of casting process simulation “HeatandMass Flow Analyzer”. Based on this analytical model, Victo Paschkis made a heat conduction analysis on the sand mold in 1944, and many of his research results were published in the famous AFS bulletin.

In 1962, Fursund of Denmark studied the influence of heat transfer in sand mold on the surface quality of steel castings. It was the first time that the paper was published in the computer simulation literature. It was the first time that the finite difference approximation method was applied to the heat transfer calculation of solidification process, It has opened up a new way to study solidification theory with computer numerical calculation method [21. In 1959, Campbell and Villen Weider of General Electric Company studied the application of finite difference method (FDM) to simulate the production of large and thick castings, and developed a predictable solidification mold in 1965. However, FDM method cannot track the free surface of metal during mold filling, so in the early 1980s, a method called flow volume method (Volume of Flow: VOF), introduced by Hirt and Nicholas, takes the flow volume function as the main parameter to track the flow free surface. These initial attempts made researchers realize the broad prospects and great potential of solidification simulation.

In the 1960s, some people began to use FEM to solve steady-state and transient heat conduction problems. Among them, the AFS Heat Transfer Committee initiated and proposed a plan to encourage further research. Researchers from the University of Michigan published some important documents: Rober Pehlke and James Wilkes simulated the sand mold casting process, and filled various materials including carbon steel, aluminum and error-containing brass alloy. The results show that the FDM method is largely affected by the thermophysical parameters of the filling medium.

In 1973, Victor Davies of Norway and others applied FDM method to sand casting, metal casting and low pressure casting when filling aluminum products. In 1974, Los Alamos Scientific Laboratory developed the computer-generated color moving picture technology. This technology uses standard microfilm shooting device. Through the control program set for a series of optical filters, 11 composite colors are used to describe different temperature ranges, and finally produce strip or speckled images, realizing the visualization of solidification simulation technology mold profile.

In the 1980s, with the improvement of computer technology, more mathematical calculation models were established. These models can simulate the filling process and wave body flow mode, predict the change of filling temperature and the impact of these factors on the casting quality. In the early 1980s, the assumption of instantaneous mold filling was applied to a certain extent. In the late 1980s, mold filling simulation technology was rapidly developed and applied to actual production. Using mold filling simulation can effectively improve the mold filling system, eliminate casting defects caused by flow, produce an optimal temperature distribution for solidification and feeding, and improve the quality and yield of castings.

In the 1990s, the computer numerical simulation technology of casting process was further promoted, and the microstructure simulation was developed. In addition to having a deeper impact on metallurgy, it can also predict the mechanical properties of castings. Shortly after that, people realized the flow process of molten gold in the growing dendrite fragments through convection and diffusion simulation [. In the late 1990s, the simulation study of stress and deformation was more conducive to controlling the distortion of castings, reducing residual stress, eliminating hot cracks and cracks to the maximum extent, reducing mold deformation, and improving the service life of molds.

At the beginning of the 21st century, the development of 3D numerical simulation software abroad has tended to be perfect. Due to the rapid development of computer technology, numerical simulation has obtained unprecedented research and development. All kinds of commercial casting software have been widely used in practical production and achieved good results. This is largely due to the popularity of high-performance computers and the maturity and perfection of casting theories and models. The casting solidification simulation is gradually transiting from heat transfer model to heat and mass transfer and flow comprehensive model, and the mold filling simulation of liquid metal has become a frontier topic.