Study On The Technology Of Computer-Aided Geometric Tolerance Types Generation

Based on the "Study on Computer Aided Tolerancing System" and "Design Theory of Integration Tolerance Based on Geometrical Product Specifications" (National Nature Science Fund Project, No: 59705022, 50275136), the technology of computer-aided geometric tolerance types generation is presented. The prototype system for computer-aided geometric tolerance types is developed.In the first chapter, the development and State-of-the-arts of computer aided tolerancing system at home and abroad are summarized. The key techniques of computer-aided geometric tolerance are analyzed. At last, Main contents and general structure scheme of this dissertation are present.In the second chapter, based on new feature defined by ISO/TC213 and TTRS theories, seven symmetrical features are classified and analyzed. Variational geometric constraints (VGC) are classified as self-referenced VGC, cross-referenced VGC and mating VGC. Seven kinds of self-referenced VGC, twenty-seven kinds of basic cross-referenced VGC and six kinds mating VGC are classified.In the third chapter, based on the theories of graph theory, mate tree and loop circuit are proposed. Evaluation rules of well-constrained VGCN are studied. Then, the flow charts of VGCN generation and evaluation are given. At last, based on MDT, the VGCN is established.In the fourth chapter, according to the GB/T 1182-1996, tolerances are classified into self-referenced tolerance and cross-referenced tolerance. The corresponding relationship between self-referenced & cross-referenced VGC and self-referenced & cross-referenced tolerance are studied. The method and process of well-referenced tolerance types are discussed.In the fifth chapter, the prototype system for geometric tolerance types generation is built on MDT. The system comprises three modules. The example is studied to demonstrate that the system can effectively work.In the sixth chapter, all of the work in this dissertation is summed up. The future research of computer-aided tolerancing is prospected.