Research On Methodologies For Converting Design Features To Machining Features

Along with increasing of market competition, industries generally adopt the new theory and method to shorten the period of product design. Nowadays, there still exist some problems in the implementation of these theories and methods, but they can indeed save a lot of time during the design period. As another period of product design– period of process planning, there is no good tool which can be used to improve its efficiency, and, in general, process planning of product is completed almost manually by engineer. It not only consumes a lot of human and material resource, but also postpones the time for bringing the products to markets. To address this issue, after studying and analyzing the present status of part design and process planning both in China and abroad, an approach for converting design features in a part model into machining features is presented, which can be developed to a key technique for promoting the automation of process planning.The first work of this thesis is to present an approach for reconstructing part CAD models by selecting proper feature representations so that they are more consistent with machining processes. This method, with the 3D mathematical model of part as input, recognizes its connotative information, and then reconstructs the part model according to style and direction of process. The model reconstructed is expressed by a sequence of features, which are used in feature recognition, conversion and sorting in the next steps. Not only the features are associated with the style of part machining, but also the type of feature must be correspondent to one machining style. Thus, the efficiency of the following computation is improved.The second work of this thesis is to develop an approach for converting design features in a part model into machining features. The input data of the approach is the sequence of features constructed in the previous work. In the process of feature conversion, the sequence of part feature is compared with the blank model, and then machining features are constructed. But these features are out-of-order; there is no any relation with each other. So the machining features should be sorted so that they can be used in design process planning. In this sorting step, the process route would be created as many as possible, and then the best one would be chosen by process designer. As another option, it can be input to other software for the further process planning work.Based on the work mentioned above, a prototype system for part feature reconstruction, feature conversion, feature sorting on transformation of feature information has been developed to validate the ideas and methods proposed in this thesis. The software development platform is Visual C++ 6.0 and UG II NX2.0, and the prototype system mainly consists of four sub-modules; that is, feature reconstruction, conversion, merging and sorting. Some practical examples are used to validate the correctness and effectiveness of the research results. In the end of the thesis, some conclusions have been drawn and the future directions in the field are given.