Research Of NC Automatic Programming Based On Technological Feature Recognition

The current NC automatic programming systems can only capture low-level geometric information of products from CAD systems; can not automatically capture the geometry of the product information and the product senior features and semantic information. Consequently, the whole CNC programming process must be completed through graphical interaction by the participation of experienced engineers, The degree of automation and programming rate is so low that the feature-based NC programming becomes a hot research issue currently. But the current feature recognition systems were designed for capturing underlying features and failed to recognize the technological features. Therefore, it is very significant to improve the processing efficiency by studying research automatic recognition method oriented product technological features and developing the CNC automatic programming system based on it.In view of problems in electrode processing such as duplication of labor, low processing inefficiency, superior programming resources losing easily, this paper achieves the NC automatic programming technology based on the technological features recognition by combining with the Mole-electrodes features and the processing requirements of modern enterprise, analyzing and identifying the part information in STEP standard neutral file, making up the map relationship between the process characteristics and the "learning" process from outside, and finally completed the design and development of TFeature prototype system. The system can recognize a variety of technological features and program automatically, and it improved the efficiency of the mold electrode processing. The main content and results are as following:1,Research the key integration technology of CAD/CAPP/CAM, and introduces the feature recognition technology and CNC automatic programming techniques. A technological feature recognition method to improve the efficiency of NC automatic programming is proposed for the special processing field; 2,The STEP file format of parts is studied, and deep analysis is made for the geometry information and topology information of boundary representation. According to mould electrode processing technology, the entity information extraction method not dependent on EXPRESS grammar is put forward to extracted the entity information of the parts;3,According to mould electrode processing industry and on the basis of the electrode processing technology, this paper defines the technological features. The extracted entity information is reformulated by means of attribute adjacency graph(AAG) and combination reasoning method, and the rules of technological feature recognition are established, and the technological feature of part is recognized finally;4,A automatic programming module with learning function is established, which can learn good processing and store it. And the mapping between processes and process features is established that the user can automatically invoke appropriate processing technology learned in the system correspondingly, and then the system can automatically process practically according to the technical characteristics;5,With Visual Basic2005 as development environment, TFeature prototype system that has learning and derivation function was developed by use of the Macro recording function of PowerMILL. The system is able to identify various technological features and learn the excellent programming technology that can reduce repeated labor and improve the processing programming efficiency.