Reverse Engineering, Measurement Technology Research

Measuring technologies with 3D-coordinates measuring machines (CMM) for reverse engineering were investigated to implement the distribution of sampling points of curves and surfaces, probe parameters setting and probe radius compensation, to plan reasonable measuring paths. An automatic measuring program for curves and surfaces was developed with visual Winmeil and fast measuring technologies of freeform curves and surfaces are analyzed and studied farther.Firstly, from general measure principle, the structure types and function of CMM, B-spline function which is the mathematical basis of spline fitting for freeform curves and surfaces, are introduced briefly. The theoretic basis is provided for realization of fast modeling about freeform curves and surfaces.Secondly, the avoidance obstacle points were determined rationally and optimal design of measuring path was developed by comparing two-dimensional compensation with three-dimensional compensation and the analysis of equal-chords distribution and adaptive distribution measuring path was divided. The automatic measurement of the workpiece space outlines with point positioning and continuous scan pattern were introduced individually by control system component. The measuring method, flow chart and export format of file and program interface of cam and blade, as a typical example, were supplied in order to explain the application field of CMM.Finally, the measuring error sources of CMM were analyzed and outlined in order to minimize the measuring error. A general measuring method was realized by combining CMM with professional software. Part model was made with freeform curves and surfaces measured in the CMM and professional software.