With the rapid development of manufacturing technology, the traditional simulation of machining can not meet the people’s need. Research on virtual machining environment is one of the key parts of virtual manufacturi...With the rapid development of manufacturing technology, the traditional simulation of machining can not meet the people’s need. Research on virtual machining environment is one of the key parts of virtual manufacturing technology. According to the features of virtual turning, this paper proposes a simplified Whitted lighting model based on analysis of Phong and other local illumination model. This model takes the material and roughness of workpiece into account to calculate the roughness coefficient D, geometric fading coefficient G and Fresenel transmission coefficient F’ so that the light intensity in the scene can be got more realisticly. Moreover, to obtain the natural lighting effects, based on the analysis of motion space of machine tools, local ray tracing algorithm is given to calculate the light intensity of every position during the course of simulation. This method can not only simulate the machining environment accurately, but also reduce the calculating time greatly. For example, if CPU is 1.3 G and internal memory is 128 M, the refresh time using the original algorithm is 0.1 second, while it becomes 0.01 seconds by local refreshing. Besides, to get more realistic machining scene, the paper deduce the transfer matrix from chip coordinate to feeding coordinate so that the chip model can be integrated into the whole machining scene. At last, a example of virtual cutting scene is shown to demonstrate the effects of global illumination model and helical chip simulation. The system can give the user high true sensation. The user can operate the machine tools through the controlling panel and watch the cutting process from different viewing angle. The data needed for construction of scene and chip simulation is obtained form the C616 lathe. This study plays important role in richening virtual manufacturing theory and promoting the development of advanced manufacturing technology.展开更多
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文摘With the rapid development of manufacturing technology, the traditional simulation of machining can not meet the people’s need. Research on virtual machining environment is one of the key parts of virtual manufacturing technology. According to the features of virtual turning, this paper proposes a simplified Whitted lighting model based on analysis of Phong and other local illumination model. This model takes the material and roughness of workpiece into account to calculate the roughness coefficient D, geometric fading coefficient G and Fresenel transmission coefficient F’ so that the light intensity in the scene can be got more realisticly. Moreover, to obtain the natural lighting effects, based on the analysis of motion space of machine tools, local ray tracing algorithm is given to calculate the light intensity of every position during the course of simulation. This method can not only simulate the machining environment accurately, but also reduce the calculating time greatly. For example, if CPU is 1.3 G and internal memory is 128 M, the refresh time using the original algorithm is 0.1 second, while it becomes 0.01 seconds by local refreshing. Besides, to get more realistic machining scene, the paper deduce the transfer matrix from chip coordinate to feeding coordinate so that the chip model can be integrated into the whole machining scene. At last, a example of virtual cutting scene is shown to demonstrate the effects of global illumination model and helical chip simulation. The system can give the user high true sensation. The user can operate the machine tools through the controlling panel and watch the cutting process from different viewing angle. The data needed for construction of scene and chip simulation is obtained form the C616 lathe. This study plays important role in richening virtual manufacturing theory and promoting the development of advanced manufacturing technology.
