| Summary: | 碩士 === 南台科技大學 === 機械工程系 === 97 === This study develops a low-cost highly sensitive there dimensional touch trigger probe with real-time observation. The development of touch trigger probe is consisted of four parts, which are the stylus with a probe tip, suspension structure, sensors and image systems. The development of probe tip to be smaller than 100μm used Micro-EDM machine, and probe characteristics in accordance with the design of stiffness for the suspension structure. For the design of the suspension structure, this study used micro beam design, and determined the length, and diameter of the micro beam, and the dimension of the suspension structure, according to the selected contact forces. The test results were analyzed and validated with finite element software ANSYS and the theoretic deduction of analytical formula. It proved that the suspension structure has the feature of inhibiting three degree of freedom, lowering the measurement error of the sensor, improving equal stiffness of the entire touch trigger probe with the selected probe length, and reducing the pre-travel error of the touch trigger probe due to different stiffness.
The development of the sensor used optical displacement and angular sensor improved from the pick-up head inside the DVD player available on the market, and used it as the sensory device for the touch trigger probe. The ball is less than 100μm is not easy to identify with the naked eye, the need for an imaging system with a probe to observe the situation. The imaging system using the webcam and microscope, and according to the design of geometrical optics to the required depth of field, magnification and field of view, and to the use of optical simulation software ASAP.
When the probe tip touches the surface of the object to be tested, the resulting contact force would be transmitted from the probe to the suspension structure, and lead to displacement or angular deviation generated by the stiff body connected to the probe, and the sensor records the displacement or angular deviation, and generates a touch-off signal when the deviation reaches the trigger threshold. It would be used as the reference for each axial displacement of the three-axis positioning platform. At the same time, imaging system to observe the probe tip touch the object and surface profile, when it comes to the naked eye does not recognize the holes, you can determine the location of the mobile probe.
Based on the experiment, the X/Y/Z measuring range of the touch trigger probe is ±2.5μm×±2.5μm×3μm, the measuring uncertainty is 96.96nm, probing force is smaller than 0.01mN.
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