The Research On Digital Modeling And Normative Design Of Typical Geometric Features Based On GPS

With the developing of information and automation technology, Traditional tolerance design which is based on experience can not meet the needs of manufacturing development. So the digital design of tolerance is desperately needed, but because of that tolerance is the key parameter which realizes functions and coordinate the technical with economic of the products and tolerance design is a typical progress which can be influenced by multi-factors, for example:the function,struncture,processing,assembly,inspection,material and so on.Because of the above impact factors, at present there is no a uniform normative design method. As a result there is a lack of unified standard in the course of design, manufacture and inspection. With the aim to solve these problems, the new generation of GPS is a system which integrates normative design and measurement authentication. It offers theories about the features, elements, skin model and duality. These theories helps to solve the problems of digital design of tolerance based on the function of the product. Normative model is the bond of guiding the tolerance design; normative operator is the approach to realize the digital design of tolerance; the both provide the basic of realizing duality of normative design and measurement authentication.In the thesis, digital modeling and normative design of typical geometric features based on GPS are studied the main work is as follows:Firstly, Research on The basic related theory of GPS. The difference and relationship between features, elements, skin model and duality are analyzed. Then, the important role of duality which is played in the product life cycle is discussed, the duality in the design and measurement attestation is studied, and the important roles of GPS in the manufacturing are summarized.Secondly, based on the theory of SDT, the dimensional tolerances domain modeling of geometric tolerance zone is researched, then based on the new generation of GPS, typical shape tolerances(straightness, flatness, roundness, cylindricity) and position tolerance are(parallelism) specificity, establishing typical geometric tolerance domain digital model, realizing the unified mathematical expression of the definition and description of the elements.Thirdly, based on the Monte Carlo theory and Surface fitting technology, virtual simulation of typical geometric tolerance is studied, then skin models of typical contours of geometric features are constructed; the influences of materials, processing technology, the structure on the skin surface is researched, rules for rounding of skin models of typical geometric features are established; generation method of skin model which has normative requirements of flatness, spatial straightness and cylindricity.Fourthly, normative design is studied. According to the different characteristics, Normative operators are realized in VB based the skin models established, characteristic values are given, in the last, Probability and statistics methods are used to obtain normative characteristic values, which guides tolerance design Lastly, the development for prototype system. With VB in CATIA the prototype system of digital model of typical features and normative design is developed. Then.An application is given to illustrate the functions of the software.