An integrated modeling method of unified tolerance representation for mechanical product

For mechanical product, tolerance includes Dimensional Tolerance, Form, Profile, Orientation, Location, Runout, and Assembly Mating Tolerance. Generally, the error of part or product is restricted by a kind of tolerance or several kinds of tolerance. In order to analyze error and its stack-up of mechanical product effectively and absolutely, this paper presents an integrated modeling method of unified tolerance representation based on Key Features (KFs) and Graph Theory in order to deal with these types of tolerances simultaneously. The method includes three steps. The first is to build a tolerance-meta model covering KFs, the relationship set of KFs, the type of tolerance, attributes of tolerance, and variational direction of KF. The model of Dimensional Tolerance, Form, Profile, Orientation, Location, and Runout can be built by tolerance-meta model. The second is to build a model of part's tolerance and Assembly Mating Tolerance based on sum arithmetic of Graph Theory. The third is to build the integrated tolerance model including Dimensional Tolerance, Form, Profile, Orientation, Location, Runout, and Assembly Mating Tolerance. The integrated model is propitious to represent tolerancing experience from engineers. The method is applied successfully to build the integrated tolerance model for a component of aircraft's fuselage.