Evaporative Pattern Casting Detection And Reconstruction Technique Reasearch

Based on the systematic analyses of model data measurement and model restructured method for both domestic and abroad large part in the field of reverse engineering, this thesis makes a systematic research on the measurement method of evanescent mode used for large casting, the pre-processing technology of three-D measurement and the restructuring technology of curved surface etc.Using the Three-D Measurement method, which is combined close-range photography measurement with binocular stereoscopic vision on the evanescent mode used for large castings and putting a foundation on the structural characteristics of evanescent mode used for large castings, this thesis carries out the route planning used in the process of measuring. It analyzes the impact on the splicing error and the surface reconstruction caused by the quantity of monumented points, the way of distribution and the size of spacing. Besides, it also points out that the selection criteria of distribution for the monumented points, which are used in the detection process. Experiments have verified that this kind of methods can achieve the goal of Three-D measurement on the evanescent mode used for large castings quickly and accuratcly.Based on the Three-D measuring data of the evanescent mode used for large castings, this thesis systematically introduces the mathematical model of Bezier, B-sample band and NURBS curved surface as well as their advantages and disadvantages, and then, it completes the combination of those three kinds of curves, at last, the NURBS surface reconstruction of evanescent mode used for large castings accomplished is in CATIA. This thesis also systematically introduces the rectification method about the three kinds of Point Cloud data and mathematical model, and it studies on the theory and the method of three-D direct detection, Two dimensions section detection as well as Slide tolerance. The thesis has completed the detection of evanescent mode used for large castings and generates the detecting reports, which will provide a faster and easier way for the detecting of evanescent mode used for large castings.