| Abstract
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1965 |
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Optical Measuring Device for Radial Error of Micro-spindle Using High-speed Photo-amplifiers |
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Metrology: Instrumentation, Design & Testing |
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| Content |
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In recent year, micro machine tools have been studied and developed for space, energy and resource savings. A micro-spindle, which is a miniaturized spindle, is one of the main components of miniaturized machine tools. It is comparatively easy for a micro-spindle to run at high-speed because the rotor of the micro-spindle is thin and lightweight. Therefore, a micro-spindle system with a maximum rotation speed of 300,000 rpm has already been demonstrated.
The measurement of the spindle rotation accuracy, which is the width of the run-out, is very important to verify the machining accuracy. A conventional measurement method uses capacitive displacement sensors and a target which is a high-precision ball or cylinder. However, the target attached to a micro-spindle must be small and light to avoid an unbalance of the spindle. In addition, capacitive displacement sensors have limitations in the applicable radius of the target and are not suitable for measuring the displacement of a small target at ultra-high speed. Therefore the conventional measuring method can not precisely measure the rotation accuracy of the micro-spindle.
Authors have proposed the optical measuring method for the rotation accuracy of micro-spindles, which is based on the Holster’s method. In this method, the rotation accuracy is evaluated according to the movement of the reflected light from the target sphere attached to spindle end, and a small target sphere can be targeted because the light beam is condensed by the objective lens. In addition, this method has advantages such as non-contact, long working distance and insusceptibility to electric noises. Moreover, authors have succeeded to relax the effect of the surface of the target sphere in the measurement accuracy by applying the algorism of the three point method.
In this paper, we have tried to improve the measurement accuracy and the response speed by reconsidering the measuring circuits and the light source of the measuring device. First, we describe the principle of the optical measuring method and the basic characteristic of the measuring system. Then, we refer to the improved measuring device and show some of the measurement data of the rotation accuracy. Finally, we summarize the results of this paper.
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