Study on dimensional measurements based on rotating wire probe and acoustic emission touch sensing




Elfurjani, Salah

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There is an increasing trend towards miniaturization of micro features as well as micro parts. In order to accurately produce these components and the miniaturized features on them, accurate measurement of the component dimensions is required. However, there are limitations in the dimensional measurement of miniature components: micro-probes and Micro coordinate machines (micro-CMMs) suitable for micro-feature measurement are expensive and fragile so it can be difficult to justify the cost for dimensional verification of batch-produced parts (in many cases miniature components are batch-produced). Therefore, a new cost-effective way for dimensional measurement of miniature components is needed. With this in mind, this thesis describes the development of a novel, three-dimensional measurement system using a rotating wire as a probe and acoustic emissions for contact sensing. This study presents a novel concept of three-dimensional measurements using a rotating wire as a probe and acoustic emission for contact sensing. Experimental results show that the probing system can measure a part with high repeatability. A controller algorithm has been developed for automated scanning within a machine tool. The performance is verified against calibration artifacts. The main contributions of this thesis are as follows: firstly, the traditional contact and non-contact micro coordinate measuring machines including sensing techniques and acoustic emission sensing are reviewed, and a clear set of knowledge gaps are identified in these fields. Secondly, a novel concept of three-dimensional measurements using a rotating wire as a probe tip and acoustic emission for contact sensing is introduced. The operation and measurements of the rotating micro probing based on acoustic emission (AE) sensing are validated experimentally. Initially, the ability of the rotating microprobe tip based on AE sensing to counteract the measured surfaces interaction rubbing is investigated. Other areas of validation are in the determination of the probing point repeatability, the straightness, and probe tip calibration. Thirdly, the acoustic emission signal and its characterizations of the probe tip touches are studied. The behavior of the rotating probe tip focusses on the threshold, touching time and as well as measured materials type that has an effect on probing accuracy. Finally, the estimated effective diameter and approximation threshold are modeled. This work is directly aimed at ensuring that the developed rotating probe tip based on AE sensing is capable of operating in an industrial metrology environment. It is concluded that the developed rotating probe tip based on AE sensing will be able to address the current needs of the micro-CMM community. On the other hand, it is possible that the rotating wire probe tip based on AE sensing can measure micro holes less than the achieved in this work, further increasing its usefulness.



Metrology Acoustic emission Measuring instrument Probing system Micro hole Wire probe