Beitrag zur Messunsicherheitsermittlung für die Messung großer Zahnräder zur Erweiterung des virtuellen Koordinatenmessgerätes der Physikalisch-Technischen Bundesanstalt

Description

In this work, influences on the measurement process regarding a large gear ring measurement standard of the German national metrology institute (Physikalisch-Technische Bundesanstalt) using a large coordinate measuring machine (CMM) are investigated. The examinations lead to the detection and definition of present influences on the measurement process and the determination of resulting measurement deviations and uncertainties. This enables to model the influences of this specific measurement task so that adaptions and expansions can be implemented in the virtual CMM, a software tool named VCMM. The resulting virtual measurement samples of the complex measurement process enable to statistically determine the task-specific measurement uncertainty. For modelling these it is necessary to know the impact of the machine and workpiece-specific influences on measurement results in detail. Therefore, systematic and random shares of the measurement deviations can be identified. In the scope of this work, firstly, the measuring machine regarding the parameters of a geometrical definition of the large CMM´s structure also under thermal influences is considered. Furthermore, the behaviour of the large gear as a workpiece is considered due to thermal and gravitational influences. The findings provide an important contribution to the extension of the virtual measurement process of a large CMM and the determination of the resulting measurement uncertainty for measurements of large workpieces.