Application status of computer simulation in Lost Foam Casting

Lost foam casting numerical simulation technology has become a powerful simulation and simulation technology, and goes deep into all aspects of casting molding process. In the lost foam casting process, numerical simulation is mainly reflected in the following four aspects.

(1) Numerical simulation of mold filling and solidification. The numerical simulation of solidification process has appeared as early as the middle of last century. Many algorithms have been studied, such as numerical method and analytical method, three-dimensional finite difference method, three-dimensional finite element method and parallel algorithm. They mainly simulate the filling process in sand casting. The design of gating system is its future development direction. At present, the research of mold filling numerical simulation technology has become more and more mature. Practicability and accuracy are the main concerns of current numerical simulation technology.

(2) Prediction of shrinkage cavity and porosity. Shrinkage porosity and shrinkage cavity of steel castings is regarded as the criterion, which is to convert it from two-dimensional to three-dimensional, so as to simulate the formation of shrinkage porosity and shrinkage cavity. Numerical simulation technology has become more and more mature, and it is also developing effectively in the image simulation technology of shrinkage porosity and shrinkage cavity of lost foam castings.

(3) Numerical simulation of stress field in solidification process. In the early 1980s, the numerical simulation technology of residual stress and residual strain of lost foam castings has been started, and the stress field when solid-liquid two phases coexist is the core of the numerical simulation of stress field in the solidification process. In recent decades, based on the finite element analysis technology, the numerical simulation software not only has the function of stress analysis, but also establishes the corresponding mathematical model. With the development of rheology, it opens up a new research direction for the behavior of two-phase region. In addition, the finite element method and finite difference method can also be combined.

(4) Numerical simulation of microstructure during solidification. Researchers began to study the numerical simulation of the microstructure of lost foam castings in the 1990s. Phase field, randomness and mesoscopic scale simulation are the main ways to simulate the microstructure of lost foam castings.

It can be seen from the above that the lost foam casting numerical simulation technology can simulate the defects produced in the actual production, such as shrinkage porosity, shrinkage cavity, crack and other defects, and analyze the causes. By comparing different process schemes, the lost foam casting process can be optimized, and finally the lost foam casting defects in the actual production can be reduced or even eliminated, So as to improve the quality of products. Because the simulation and prediction of product quality is carried out on the computer, there is no actual production of lost foam castings, which not only saves human, material and financial resources, but also improves the production efficiency and economic benefits.