| Virtual cutting is a technology which can implement the dynamic simulation of cutting processes on the computer. The aim of virtual machining system is to develop a visible machining environment to simulate and evaluate the influence of various machining process to machining result.Nowadays, CNC machine tools are used widely in manufacturing. In order to reduce the cost of test cuts, the simulation of CNC processes is needed; CNC codes are checked on the computer in virtual cutting. On the other hand, it can also improve greatly the effect of teaching and training of CNC machine tools.The key technology of CNC turning simulation in 3D is discussed in this paper. Virtual CNC turning system V2.0 is developed on the platform of Virtual turning system V1.0, VC++6.0 and OpenGL.This project is accomplished as follows:1. Sum up the methods of solving 3D geometry molding problem and put forward a blend molding mode on the study of 3D geometry molding. Divide the geometry model into static model and dynamic model. An entity input interface is developed for the static model. System platform can mold a static 3D geometry model quickly by this interface.2. A virtual module library is created by the use of OpenGL display list technology. The 3D sence of Virtual CNC turning system is built by virtual assembly technology using the virtual module library, which is referenced on the CYNC-400 numerical control machine in Engineering Training Center of SooChow University. Motion control model of virtual machine tool is built by numerical control interpolation technology and 3D simulation of turning is implemented by computer cartoon technology. The dynamic model of virtual workpiece is built by discrete method.3. The graphics check and information report of collision and interference is implemented. User can not only see the graphics display of collision and interference, but also know the coordinate of tool position when collision or interference happens. It offers convenience for user to consummate his NC code.4. Because of the lack of virtual part management in virtual machining research, a virtual part library is developed to manage the virtual part. It can do 3D observe transform, file management, virtual measure, remachining to virtual part and generate physics simulation report. These functions can make the virtual part resource more useful.5. Put forward the content of physics simulation of this paper on the study of physics simulation technology. The stable cutting force forecast model is built on the research of cutting force source and measure. Through analyze of error molding, a technics coordinate system is built and a resolve mathematical model of workpiece error in this coordinate system is given. The workpiece distortion error model of stable cutting force is built. By using these models, the forecast of cutting force and workpiece error is achieved.With its successful simulation and good use interface, this system will bring great convenience to CNC teaching.
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