Research And Application Of The Key Techniques In Reverse Engineering For Large-scale Complex Parts

Reverse engineering is an important research area of advanced manufacturingtechnology. With its further theoretical research and gradually expanding applied range, RE,as an independent research branch in CAD/CAM, is one important way to improve productinnovative design and enhance manufacturing level.This dissertation majors in two aspects of work about the technology of process of RE:theoretical research and practical application with the blade of wind turbine, oil drill, andcotton picking ingot as research objects.Compared to the reverse process of common parts, large-scale complex parts' reversetechnology has certain particularity. This dissertation conducts research on the keytechnologies of RE and summarized digital method for measuring and simplified point clouddata as well as the reconstruction of complex surface. On this basis, this dissertation developsan improved method and innovative research on RE technology in order to accommodatereverse large-scale complex parts. In digital measurement and data processing, thisdissertation focuses on measurement methods and principles of the optical scanning and putsforward specific measurement method for large-scale complex parts and planningmeasurement path and achieves the measurement example of large-scale complex part as well.Based on such common methods in the field of point cloud data processing as bounding boxmethod, random sampling method and uniform grid method etc, this dissertation presents adata simplified algorithm based on curvature variation. This algorithm can search each pointneighborhood and estimate curvature in uniform and non-uniform point cloud as well assimplify point cloud data according to curvature values. Though processing point cloud dataof Oil drill with complex surface, the algorithm is approved to be valid ensuring the accuracyof surface reconstruction. In model reconstruction, this dissertation puts forward an improved3D space division algorithm based on Bézier and NURBS parameters surface reconstruction. The method uses Coons surface as transition surface and transforms Bézier surface intoNURBS surface. Therefore, it enhances the flexibility and adaptability of surfacereconstruction and remains better versatility with CAD／CAM system.In applied reverse technology, combined with distinguishing region characteristics inXinjiang, this dissertation completes digital measurement for wind turbine blades that islarge-scale complex parts in wind turbine industry using such technologies as digitalmeasurement and surface reconstruction. In the same way, reverse Oil drill and reverse cottonpicking ingot are achieved.In addition, according to the practical requirements and demands of key partslocalization of large-scale cotton picker, reverse technology is applied to reverse material ofcotton picking ingot. Through the detection of energy spectrum for internal material of cottonpicking ingot, the reverse material chemical composition of cotton picking ingot and its heattreatment process are obtained. These contribute to enhance cotton picking ingot's workingperformance and provide important reference for rapid prototype.