Study On Intelligent Theory And Application Of Machining System Design For Complex Surfaces

Based on extensive survey and analysis of existing complex workpiece surface machining system design (cutting tool edge profile design and tool path generation) methods, especially application of CAD and AI techniques, tentative research work was carried out on intelligent theory of machining system design for complex surface.Combining analysis and syntheais (?)thods, a series of intellectualization principles and techniques for machi(?) system design has been established based on decomposition and reconstitute model, so providing intelligent CAD system with high adaptability and potential innovative power. The machining experiments and practical application in production have shown that the theoretical model and principles and methods derived from it are correct and effective.Decomposition and reconstitute model is the theoretical basis of all the intellectualization principles and techniques in complex surface machining system design proposed in this study. It includes the following decomposition and reconstitute of complex surfaces, form cutting system schemes, cutting tool edge, cutting motion and man-machine system itself. From the view point of design, it consists of decompositions and reconstitute of initial requirements, design contents, design process. Design intelligence analysis and reconstitute has derived the now way of intellectualizing design system by providing it with "cognitive and recognition power".Giving shape to workpiece is the primary and the most important function of the machining system. Workpiece surface is firstly classified into two categories: design model and machining model, and the relation between them is studied and conversion from the former to the latter is discussed. Then, according to characteristics of machining process, the machining model is further divided and put into three levels in hierarchical form: micro, local and overall levels. Finally, discrete space structure is established for workpiece surface based on granularity conception and decomposition and reconstitute model.Automatic creation of form cutting system scheme is the decisive element for design systems with innovative potential. After extensive analysis of characteristics of various machining systems, a new synthetic principle is firstly proposed for machining system scheme formation based on 3 dimensions of machining allowance. Then, to provide design system with true innovativepotential, a variety of basic and complex surfaces is analyzed synthetically, and recognition and inference principle is applied for complex surface recognition. Finally, an innovative case is studied to make the conical end ? milling cutter with constant helical angle, which derived a new machining system, so as to demonstrate the effectiveness of the above intcllcctualization principle.Form cutting tool profile and hob profile design is most important task in traditional machining system design. In this work, decomposition and reconstitute of profile design process is made use of in establishing general-purpose and fully automatic design system. Firstly, the profile of rotary cutter for helicoid surface is obtained through 3D methods, which adapts itself to. frequently changing relative positions between tool and workpicce, and ever-changing workpiece surface, and needs not human derivation of conjugation formula. Then, the method is applied further to hob profile design. To cut down computing time, 2B design method is adopted called discrete-and-synthesis method, and its result is taken as the initial "heuristic" value of 3D solution. Reconstitute of time series leads to a refined solution' of hob profile.Tool path generation and interference checking is the basic contents in modern NC machining system design, making good use of over-all property of complex surfaces, movement scheduling is studied firstly. In order to optimize synthetically the overall machining system, i.e. 2-1/2D NC machine in the ease discussed, several optimal principles are proposed. Then, non- cutting- edge interference problem is tackled by hierarchical inference method, which especially suits to be used on micro-computer without 3D modelling system. In tool path generation on 2-1/2D NC machine, path reconstitute conception is proposed for fine cutting, and practical method is designed with satisfactory results. Finally, a new type of tool path generation method by copying principle is introduced, which is a diroct method and is made practical by local level reconstitute of workpieco surface.As application of the theoretical model and techniques established above, -intelligent CAP system is developed. Firstly, intelligent interactive CAD model is built up, making good use of existing CAD capability and human intelligence, and a new type of interface element is developed, called Prototype Menu, which makes the design system more user-friendly. Then, AI techniques arc used to develop various intelligent elements including the representation of various knowledge developed in the study, intelligent interactive control strategics, and inference engines closely related with the machining system design, e.g. workpiece surfaee recognition, machining system scheme creation, tool profile synthosis, interference checking, etc. Based on these intelligent elements, practical softwaro systems have been developed, among which WGIICAD system has been put into production over a year with effective results.