Research On Feature Based NC Machining Process For Aircraft Structural Parts

Incorporating the National Science and Technology Major Project of China, Natural ScienceFoundation of China and the actual demands from the aircraft manufacturing industry, to addresssuch process-induced problems as fixture deformation and the non optimal cutting parameters, thefeature-based NC machining process for aircraft structural parts is researched. The majorachievements of this paper are as follows:(1) The feature-based fixture design method is proposed. On the basis of summarizing oftypical fixture methods of aircraft structure parts, the relationships between fixture methods andfeatures are analyzed, to form the typical machining features related to fixture design methods andtheir dimensional parameters. The relative stiffness of the bottom and the relative stiffness of thewhole part are calculated, and the stiffness grading system is constructed on that basis. All theseform the feature-based fixture design method.(2) The feature-based cutting parameters optimization method is researched. The influence ofthe feature structures and their dimensions to the cutting parameters are analyzed, and the factorsinfluencing stiffness of the features are abstracted. Through the Finite Element Analysis (FEA) andthe artificial network prediction, the optimization model of cutting parameters is established withfixture scheme, machining strategy, feature type, feature structure as its variables, vibrationmagnitude, cutting force, machine tool power, cutting tool stiffness, cutting strategy, featureparameter as its constraints and feature-based maximum cutting force as its objective.(3) The feature-based standard machining process test model is researched. Via analyzing thestructure and process characteristics of aircraft structural parts, the typical machining features andtheir typical combinations are abstracted, the feature-based standard machining process test modelis constructed. The feasibility of testing the machining process of aircraft structural parts isdiscussed, and the test schemes of this model are also designed.(4) Based on the above research results, the prototype systems of fixture design and cuttingparameters optimization are developed, and the test model for machining aircraft structural parts isestablished. The research results have already seen its preliminary application in some aircraftmanufacturing enterprise.