| CNC machining technology greatly improves the generation efficiency of products, while making machining the parts of complex and high-precision as possible. The accuracy of CMC machining directly affects the quality of product, so the inspection of NC code has become an important means to ensure CNC machining accuracy and processing quality. CNC machining simulation not only to verify the accuracy of the NC code but also to be able to inspect the cutters, machine tools and fixtures interference, also, the simulated model can be used to verify machining precision, so it is the primary means to inspect NC code.Because of the importance of NC machining simulation technology, domestic and foreign Specialists have made a lot of research, put forward many machining simulation algorithms and developed a number of NC Machining simulation systems. But there are still problems and insufficient, such as type a single of machining simulation, the balance between simulation accuracy and simulation speed, etc. So the CNC machining simulation technology was studied in-depth, and a common set of CNC machining simulation system was developed in this paper.Since most machining simulation software only for a single machine tool or processing methods, the conceptual of instance model database was presented. The machine tools of all types, cutters were unified stored and Managed by machine tool and cutter model database, so, the all types machine tools cutters could be machined simulation. By three-dimensional solid models, topology chains and attribute parameters combination to express machine tool instances was proposed, so, the instances modeling of all types machine tools could be achieved. Two modeling methods direct modeling and external loading were put forward for cutter and work piece examples. The direct modeling was used to created common cutter models and simple work piece models by parametric, also the external loading was used to load CAD models. The diversification of cutter and work piece modeling was achieved, and the versatility of the system was guaranteed.CNC machining simulation algorithm is the key technology of CNC machining simulation, on the base of the current machining simulation algorithm, the space segmentation and graphics rendering technology combination was proposed to achieve dynamic display of simulation model in this paper. The work piece models were express by Constructive Solid Geometry (CSG), the work piece models were seen as CSG structural models composed by the work piece and cutter swept volumes. By comprehensive comparison of various methods created swept volumes of cutter, the approach based on envelope theory was adopted to create cutter swept volumes. On the other, the improved SCS algorithm was be used to dynamically render and display the work piece model. In the rendering process, the visible and invisible part of work piece model were Determined by depth test and stencil test. On this basis, dynamic display work piece model by rendering invisible part. While spatial region segmentation, cutter swept volume consolidation, occlusion query were be integrated used to reduce the numbers of cutter swept volumes rendering in process of rendering, thus the rendering efficiency was improved.Finally, a five-axis CNC machining simulation system was developed by VS2008and Open Scene Graph (OSG).The common machine tool instances were created by this simulation system, also the machining processes at different structures machine tool of five-axis were simulated, then, the simulation results was compared with the results of UG. The results show that the machining simulation of various types of machining tools can be achieved, and the accurate simulation results for CNC machining verification can be obtain by this simulation system. |
