坐标测量机孔径测量的不确定度评定模型研究

Uncertainty evaluation model for aperture measurement of coordinate measuring machines

以坐标测量机测量孔径为例,阐述测量过程中影响测量结果的不确定度来源,根据测量模型建立孔径测量的GUM法不确定度评定模型;利用对坐标测量机的测量系统量值特性指标分析的方法 ,给出基于量值特性分析法的各标准不确定度分量的评定模型。通过对汽车空调压缩机后缸体的孔径测量,比较两种方法评定的扩展不确定度。实例分析可以看出:对于坐标测量机复杂的非线性测量模型,GUM法在计算灵敏系数时,运算量较大且获得的是近似结果,因此其可操作性不强;量值特性分析法通过对测量系统整体的分析,基于大量的实验数据对测量结果进行测量不确定度评定,其流程和操作性更为便捷、有效。

The factors which may influence the measurement uncertainty of aperture measurement by coordinate measuring machine （CMM） were analyzed. Two uncertainty models were established based on guide to the expression of uncertainty in measurement （GUM） and measurement system analysis （MSA）. Measurement uncertainty for aperture of workpiece were evaluated by the two methods. Moreover, seen from the evaluation example, the results of uncertainty evaluation obtained from GUM and MSA were compared, the comparison result indicates that GUM method needs large amounts of computation and can only get the approximate results in the calculation of sensitivity coefficient but MSA method analyses the whole measurement system and evaluates uncertainty through a large number of experimental data,which is more convenient and more effective than GUM method.