Research status of casting simulation in China

Casting belongs to liquid metal forming technology. In actual production, casting engineers often make process according to previous experience, and lack of scientific and rigorous judgment on flow field, temperature field and defect location and size. However, casting defects often exist in the body, which is difficult to find by naked eyes and existing detection methods, which results in many production units There are potential quality hazards and root causes of quality accidents.

In recent years, with the large-scale application of computer numerical simulation technology, casting simulation technology has been widely used in foundry enterprises. By means of three-dimensional modeling, database analysis and visualization technology, the flow field and temperature field changes of various materials and processes in metal filling cavity stage, metal solidification stage, metal cooling stage are systematically simulated Finally, the position of the defect is predicted in advance. Casting simulation technology can complete the simulation of casting process as a whole, and then reduce the trial production cycle and defects, improve metal utilization and reduce production costs. The main research contents of casting simulation are as follows

(1) According to the theory of metal hydrodynamics, the fluidity of metal in the process of liquid punching is analyzed, and the distribution diagram of flow field is obtained. It is conducive to the simulation of the whole gating system, so as to avoid the occurrence of casting defects such as sand washing, insufficient pouring and air entrapment.

(2) Temperature field simulation, temperature field simulation analysis: it is to use the relevant theoretical knowledge of heat transfer to analyze the heat transfer process of casting, to obtain the temperature field distribution in the solidification process, so as to predict the location and size of shrinkage porosity, shrinkage cavity and other casting defects of the axle housing.

(3) Coupled simulation of flow and heat transfer: Based on the basic principles of fluid mechanics and heat transfer, and based on the simulation of filling process of axle housing, the heat transfer process can be calculated, and casting defects such as air entrapment, cold shut-off and insufficient pouring can be predicted. In addition, the temperature field distribution after mold filling can be obtained, which can provide initial conditions for the simulation of solidification process.

(4) Microstructure simulation: it is divided into macroscopic, microscopic and mesoscopic microstructural simulation. The dendrite growth rate, microstructure transformation process and nucleation number are calculated by mathematical model, so as to predict the microstructure and properties of the axle housing.

(5) Stress field simulation: Based on the basic principle of mechanics, the stress field distribution in the forming process of the axle housing is analyzed, so as to predict the casting defects such as hot crack, cold crack and deformation.