Numerical simulation of casting filling is to analyze the heat transfer phenomenon and forming ability of high temperature liquid metal in the process of mold filling, which is an important part of CAD. Through the simulation and analysis of the flow state of the liquid metal, to optimize the process design of the pouring system and riser, to prevent the liquid metal from oxidation, rolling up, inclusion, pouring shortage and other defects in the forming process; on the other hand, the control of the temperature field distribution in the forming process can provide a reference for the solidification stage, and have a certain guiding role in the prediction of the cold separation and shrinkage of the liquid metal.
The numerical simulation of solidification process is to analyze the temperature field of molten metal during the cooling and solidification process in the mold cavity, which is of great reference value to predict the shrinkage and porosity defects of casting. Solidification numerical simulation technology includes three parts: three-dimensional heat transfer numerical calculation technology, geometric modeling and defect criteria. It can reasonably predict some defects that will appear in the solidification process, and can be used to judge whether the casting process design is reasonable, so as to reduce the number of experiments and the cost of process design
1.Numerical simulation method of filling process
The filling process of liquid metal belongs to the incompressible and unsteady flow with free surface viscosity. Its whole process includes momentum transfer and energy transfer. To describe its flow, filling, heat transfer state and process completely, its control equation needs to conform to the laws of momentum conservation, mass conservation and energy conservation.
2.Numerical simulation method of solidification process
When the molten metal is poured into the mold cavity, the temperature of the molten metal will be transferred to the mold cavity, so the casting process is a process of heat energy control transfer, the whole process is accompanied by heat transfer. With the continuous heat exchange between the internal and external environment of the internal mold, and with the change of time, it also leads to the irregularity of casting defects. Therefore, in order to predict the internal defects of castings, it is necessary to accurately control the heat transfer in the casting process. In the process of solidification and heat transfer, there are three ways: heat conduction, convection and radiation.
