Design And Research On Reverse Engineering Of Globoid Indexing Cam Based On B-Spline

Automatic tool changers using cam are devices used in CNC machining tool to exchange the tool frequently in recent years. The cam is the globoid indexing cam, which is made use of in automatic tool changers. Contour surface of the cam is designed according to movement law of optimal dynamic performance, and has high indexing accuracy. But in actual application and research, the automatic tool changer by cam, which is applied in CNC, is imported entirely because the working contour surface of the cam is very complex. Design and manufacture of the cam looks hot if self-made automatic tool changer by cam is realized.This paper mainly designs and establishes math model of the working contour surface of the cam applying surface reconstruction of reverse engineering by processing measure data of a globoid indexing cam, which can provide foundation for machining and manufacture of globoid indexing cam. This paper puts emphasis upon surface reconstruction in reverse engineering, and studies the technology of interactive modeling in surface reconstruction on basis of across-the-board analyzing in the reverse engineering field.By means of using a proper data structure in surface reconstruction, the computational efficiency can be greatly improved, and at the same time the essential geometric information for the subsequent surface modeling and model analysis can be obtained. The study for preprocessing of data points in this dissertation mainly concentrates on the noise error reduction of cloud point data, smoothing data, and thinning of cloud point data by estimating curvature. Based on the processed data, computational efficiency of surface reconstruction is greatly increased, and model quality of free curve and surface is improved. In this dissertation, and the validity of methods mentioned is proven by some examples.Based on the mathematics modeling of B-spline curves and surface, the algorithm of least-squares fitting to curves and surfaces with energy items is proposed, and the algorithm of skinning approximation to scanning data by lays is presented using the algorithm of least-squares fitting to curves. In order to demostrating the smoothness of B-splines, the algorithm of curves fairing with minimal energy is proposed. In this dissertation, the principle and the procedure of various algorithms are illustrated by some examples. The investigation of provides a valid method for curved surface reconstruction in reverse engineering.