Form Error Evaluation Of Spatial Curved Surface And Its Measurement Uncertainty Estimation In OMV

On-machine verification(OMV) is one of the important methods on spatialsurface inspection. OMV technology enables automatic detection of spatial surfaceand completes the machining quality evaluation. Effective error evaluation methodcan not only improve testing efficiency but also reduce mis-rejection rate. Completemeasurement result should include the best measurement result estimation and itsuncertainty, so policy mistakes due to measurement inaccuracy can be avoided. Basedon on-machine verification system environment, form error evaluation and itsmeasurement uncertainty estimation of spatial curved surface are studied in this paper.(1) Form error evaluation and its measurement uncertainty estimation of simplesurface are researched. Cylindrical surface and conical surface are studied asexamples, evaluation methods of cylindricity error and conicity error are designedbased on sequential quadratic programming algorithm, using MATLAB forexperimental verification of its validity and advantages. Moreover, measurementuncertainty of cylindricity error is estimated by transfer method, measurementuncertainty of conicity error is estimated by Monte-Carlo simulation method, andinstances interpret their application.(2) Form error evaluation and its measurement uncertainty estimation ofsculptured surface are studied. Two local coordinate systems are constructed usingthree corner points of measurement point set and three corresponding corner points oftheoretical surface of the sculptured surface respectively. Align the two localcoordinate systems, and measurement point set is pretreated. Minimum distance frommeasuring point to the surface is calculated using subdivision approach algorithm, andlinear differential moving model of the distance function is derived. Sculpturedsurface form error is evaluated based on SQP algorithm. Measurement uncertainty ofcomplex surface form error is estimated by bootstrap method. MATLAB is utilizedfor the verification of error evaluation and uncertainty estimation algorithm.(3) GUI functionality of MATLAB software is used to develop graphical userinterface of spatial curved surface form error evaluation and its measurementuncertainty estimation. VC++development tool is utilized to design interface betweenmachine detection system and graphical user interface. Error evaluation anduncertainty estimation function module is integrated into the OMV software systemdeveloped by Tianjin University independently, and visualization of spatial curved surface form error evaluation and its uncertainty estimation algorithm are realized.