3.1 The generation of 3D models and the exchange of electronic documents How to obtain accurate electronic data models of components is a crucial first step for CA. With the development of technologies such as 3D CAD software and reverse engineering, this work has become simple and quick. Here we mainly introduce the process of entity modeling and data conversion using IDEAS. IDEAS9 integrates 3D modeling and reverse engineering modeling modules. The complex model can be obtained through the MasterModeler module (see Figure 2). It can perform parametric design of full geometry constraints and free innovation design of arbitrary geometry and engineering constraints. Surface design provides variable sweep, boundary surface and many more. The modeling function of a free-form surface. Reverse Engineering Freeform can process the point cloud information collected by the digitizer, create curves and surfaces, and design. After the surface is generated, the RPM file can be directly generated or returned to the main modeling module for processing (see Figure 4). After the entity file is generated, it needs to be converted into an STL file (see Figure 3) to be used as input to the RP device. The conversion process should pay attention to the choice of molding equipment name, usually choose SLA500, the output accuracy of the triangle is between 0.005~0.01. When using MagicRp, you should pay attention to multiply 25.4 to get the actual design size.
3.2 Numerical Simulation of Solidification Process 3.2.1 Numerical Simulation of Solidification Process Casting is a process in which a liquid metal fills a cavity and solidifies and cools therein, which contains many complex phenomena that affect the quality of the casting. In actual production, it is often empirically evaluated whether a process is feasible. For a casting, the process setting needs to pass several tests and repeatedly explore. Finally, according to the casting results of various test schemes, the casting process plan that meets the design requirements is selected. It takes a lot of manpower, material resources and financial resources for many trial castings.
Although the casting process is very complicated and has many accidental factors, it still follows basic scientific theories such as fluid mechanics, heat transfer, metal solidification, and solid mechanics. In this way, the casting process can be abstracted to solve the problem of liquid metal flow, solidification and temperature change, which is to solve the Fourier heat conduction equation and the elastoplastic equation under given initial conditions and boundary conditions. The development of computer technology has made it possible to solve numerical solutions of physical processes. Application of computer numerical simulations provides a quantitative description of extremely complex casting processes.
Through mathematical physics abstraction, the casting process can be characterized by the coupling of several types of equations:
1 Thermal energy conservation equation: 2 Continuity equation: 3 Momentum equation: The commonly used numerical simulation methods are mainly finite difference method and finite element method. The mathematical model of the finite element difference method is simple, simple and easy to understand, and takes up less memory. However, the calculation accuracy is general. When the casting has a complex boundary shape, the error is large. In the stress analysis, the differential mesh is converted into a finite element mesh for calculation. The finite element method calculates the unit according to the variational principle, and then performs the unit synthesis. The simulation accuracy is high, which can solve the problem of casting with complicated shape. Regardless of the numerical method used, the numerical simulation software for the casting process should consist of three parts: pre-processing, intermediate calculation and post-processing. Pre-processing mainly provides geometric information of castings and shells for intermediate calculations; various physical parameters of castings and shells and casting process information. The intermediate calculation is based on the physical field of the casting process design, providing a calculation model for numerical calculations and predicting the quality of the casting based on the quality of the casting or the relationship between the defect and the physical field. Post-processing refers to visually expressing the calculated results graphically. Figure 5 is a numerical simulation system composition of the casting process.
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Performance advantages:
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