Process Constraints Based Machining Feature Recognition For Aircraft Structural Parts

This work was supported by the National Natural Science Foundation of China, National S&TMajor Project, and aircraft manufacturing company. Analyzing the difficult of machining featurerecognition and sequencing because of the complicated structure and process of the aircraft structuralparts, the paper made further study into the key technology of the meta-feature recognition andsequencing. The main jobs of this paper were as follows:1) The definition and classification of meta-feature were presented. We analyzed andsummarized the typical process of the aircraft part. Then, we decomposed present machining featuresin the rule of one feature corresponding to one operation. We proposed meta-feature of the aircraftpart based on the needs of the feature information for the operation of NC programming.2) The recognition technology of meta-feature based on the re-decomposition of holistic attributeadjacency graph twice was proposed. First, we analyzed of processing technology on thecharacteristics of intersection relationship between features or within a feature. Second, werecognized machining features based on a holistic attribute adjacency graph. Third，we decomposedand recombined holistic attribute adjacency graphs in order to get meta features based on optimizedprocess, which realized that a machining feature corresponds to one machining operation.3) The method of sequencing meta features based on branch-and-bound algorithm of theminimum cost was proposed. The definition of meta-feature changed the sequence of machiningfeatures into the sequence of machining operations, which did not suffer the effects of the originalsequence of machining features again in meeting the needs of the rigid process constraint rules. Abranch-and-bound algorithm of the minimum cost for the sequence of meta-feature was suggested toachieve the shortest tool path.4) The system about meta-feature recognition for the aircraft structural part was developed onCATIA V5, which is applied to an aircraft manufacturing corporation and has been proved effective.