| Compared with the general lathe turning, NC Turning can make operators extricate from the heavy physical labor. It also can improve the accuracy of lathe turning and increase the productivity for related enterprise. On the other hand, it can significantly shorten the working hours and improve the production efficiency by using of twin-turret vertcal lathe to machining the workpiece. However, it is very difficult to make NC programs for the lathe. In this paper, a feature-based parametric CAD/CAM system for twin-turret vertcal lathe is set up by making use of object-oriented technology, NC machining technology and computer-aided technology. Under the automatically programming system, the following tasks can be completed, those are parts modeling, process planning for twin turrets, tool path generation, the treating of process parameters and the automatically producing of NC code, etc. This paper mainly discusses the following issues:1. The first part of this paper summarizes the current situation of numerical control technology. And it introduces CAD/CAM technology specifically, including the general development, working processes, main tasks, the current problems in the system and its development trend. Meanwhile, it expounds research status and key issues of twin-turret CNC programming. Finally, it raises the research purposes, significances and methods of the issue on the basis of enterprise requirements.2. Combining with design principles of CAD / CAM systems and application features of our special system, it researches on development platform for the system. According to the processing features of plate parts, requirements analysis and concept design of the special system, it educes the overall design flow model, function structure model and data flow model for the system.3. In this part, the design process for a feature-based parametric modeling module is researched. In accordance with the structure features of plate parts, this paper proposes a feature-based parametric modeling method. In the method, the first thing is classifying the plate parts to kinds of structural features, they are main features, auxiliary features, baseline features and non-shape features. Then all the features should be defined by the object-oriented methods of C++. Finally, it implements parametric modeling for plate parts through parametric technology. In addition, it gives a detailed description of the parametric modeling process for kinds of standard flanges.4. Research on the feature-based parametric planning process. Based on the method, the task division, twin-turret task allocation, determination of each process route, processing sequence, tool selection and the determination of cutting parameters are ascertained.5. The parametric generation method of NC code is expounded. Main research is focus on post processing method of the system, which generates the NC program that can be directly used for the actual production and processing enterprises. For the corporation needs of achieving automatic programming process of standard flanges is designed.6. Accomplished the design of parameric CAD/CAM sub system applied to flanges, with which a case is carried out.7. In the last part of this thesis, it shows a summary of the whole text and puts forward a few prospects for further research.
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