Task-Oriented Form And Position Measurement Uncertainty Evaluation With Coordinate Measuring Machine

The purpose of measurement is to obtain the best estimate of the measured accurately,but the measurement results will always consist of measurement uncertainty because of the impact of the unknown system errors and random errors.The measurement uncertainty is an important parameter to characterize the dispersion of measurement results.Coordinate measuring machine(CMM)is an important precision measuring instruments in the field of the mechanical measurement,which can be used to measure any size and geometric error conveniently and fast in theory.In the aspect of form and position error measurement,roundness measuring instrument,autocollimator and other special instruments or measuring implements can obtain the measurement results more accurately than the CMM,but in contrast to the special instruments or measuring implements,CMM is versatile and convenient,which is more widely used in the field of modern industrial manufacturing.In this dissertation,the uncertainty evaluation of task-oriented form and position measurement with CMM is studied and CMM is taken as the research object.The research is mainly focused on the issues of establishing the uncertainty model for the form and position measurement with CMM and quantifying each uncertainty components.A complete and universal process of uncertainty evaluation of form and position measurement with CMM is proposed at last.The main research contents are listed as follows:.Firstly,the method for evaluating measurement uncertainty through the quantum property factors based on the black box model is proposed and the sources that cause uncertainty during the measurement of CMM are analyzed.Secondly,the methods for quantifying the uncertainty components of the form and position measurement with CMM by Maximum Permissible error and maximum permissible probing error are proposed according to the characteristics of typical form and position measurement with CMM and the relevant theoretical basics.Thirdly deep and systematic research on he evaluation of measurement uncertainty based on the Monte Carlo method,Monte Carlo method and Adaptive Monte Carlo method are used to synthesize the uncertainty components respectively and the results are compared with the result which obtained by the GUM method.Moreover the limitations of GUM method are analyzed.Finally The study on flatness and parallelism measurement with CMM are carried out.The result show that the uncertainty model and the quantifying methods,which were proposed in the paper,can effectively solve the problem of uncertainty evaluation for task-oriented form and position measurement with CMM;The uncertainty component caused by the indication error do not obey the normal distribution and the proportion of it in the uncertainty components is large,so synthesizing the uncertainty components by MCM is more scientific and reasonable.