The Research On NC Programming System For Electrode Based On Case Reasoning

With the rapid development of CNC machining technique in the machinery manufacturing area and military industry field, automation of numerical control programming is also subject to greater attention. Traditional manual programming technique is time-consuming and inefficient. Programmers also need to have a high level of knowledge and a lot of experience. On the contrary, automatic programming technique reduces the workload and improves the efficiency of programmers. As part types are continuously enriched and part structure increasingly complex, the automatic programming system development has become increasingly difficult.This paper presents a method of CBR, which provides a new way for the development of automatic programming system. The CNC cases database is very large, if we can take advantage of these existing process cases, it will not only help to improve CNC programming standard level, but also to improve the versatility of the system. Take electrode automatic programming for example, based on the information models of electrode products, the features which will affect process scheme are extracted. Then through the description of the electrode cases, not only the cases base is established, but also the process of case retrieval and similarity calculation are analyzed. In additon, it can use the man-machine interface to realize the management and maintenance of the cases base. Meanwhile, introducing the 3D model retrieval technology to match the geometry characteristics of electrode products. Using 3D polar radius curved rectangular to extract the shape features and using the Euclidean distance to calculate the similarity of shape features. After retrieval is complete, there are two conditions for the electrode programming process. When the retrieval is successful, similar case is directly used to generating the NC programming, using the method of rule reasoning. When the retrieval fails, it will formulate an appropriate processing program by combining the single templates. At the same time, these two methods provide lots of interactive tools to modify parameters for optimizing the toolpath.Based on the above studies, the electrode automatic programming system has been developed on NX platform. This system includes three modules, cases base management, similar case retrieval and automatic programming. With the application of this system, programmers can quickly reuse the CNC cases database knowledge, which greatly improves the efficiency of programming and processing quality.