Mesh generation is the basis of numerical simulation. At present, there are two main methods of division, namely, finite difference method and finite element method. The division of finite element mesh is complex, which can accurately express the characteristics of castings. It is suitable for dealing with the complex flow analysis of casting filling process. The division of finite difference mesh is relatively simple, which is suitable for the analysis of temperature field in the process of sand casting of mud pump body, and the simulation speed is fast. The software ProCAST adopts the finite element method, which can truly simulate the filling process of sand casting of mud pump body.
Before using the software creo3 The 3D solid model completed by 0 has been transformed into step format and exported. Then it needs to be analyzed and repaired by geomesh software and output to gmrst format file. Finally, it is imported into the meshcast module of ProCAST software for meshing, so that the assembly position and geometric characteristics of mold and casting can be displayed completely and accurately; Importing the step format file directly into meshcast will result in the loss of the assembly position of the mold and the casting and the complete separation of the components of the assembly, as shown in Figure 1.
The software geomesh has simple modeling and meshing functions, but it is difficult to complete the complex modeling and meshing of sand casting mud pump body. Its inspection, repair and format conversion functions can greatly simplify the meshing in the process of casting simulation. Geomesh can read the three-dimensional solid models in step, IGS, STL and other formats, and check and repair the free edges and overlapping edges of the geometric models of sand mold casting mud pump body, gating system and sand mold in the assembly (as shown in Figure 2). After the repair of the geometric model is completed, Hide other parts in the assembly and export sand mold casting mud pump body, gating system and sand mold one by one in gmrst format.
The repaired gmrst file was read in meshcast, and the finite element mesh of sand casting mud pump body, gating system and sand mold was divided. Meshcast first divides the geometric model into face meshes, then checks and repairs the generated face meshes, and finally divides and optimizes the volume meshes. During casting simulation calculation, the grid parameters of sand casting mud pump body and gating system are required to be higher, while the grid requirements of sand mold are lower. At the same time, due to the complex structure of sand casting mud pump body, it is necessary to adopt uneven grid division for sand casting mud pump body, gating system and sand mold, Dense grids are used to deal with the parts with large geometric change gradient such as the pump tail, so as to truly retain the geometric characteristics of the sand casting mud pump body as much as possible. When dealing with the parts and molds with small geometric change gradient of castings, they should be divided into relatively sparse grids. In this way, the calculation accuracy and accuracy can be improved and the calculation time can be reduced. The divided finite element mesh is shown in Fig. 3.