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Proceedings Paper

Development of a 3D touch trigger probe using micro spherical stylus machining by micro-EDM for micro-CMM
Author(s): Chih-Liang Chu; Yi-Lin Chen; Tzu-Yao Tai; Yun-Hui Liu; Cheng-Hsin Chuang; Chin-Tu Lu
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Paper Abstract

This study develops a low-cost three-dimensional touch trigger probe for micro-CMM using micro spherical stylus machining by micro-EDM. The tip ball of the stylus, with a diameter smaller than 100 μm, is made by a micro electro discharge machine with the method of wire electro discharge grinding (WEDG). The current study uses tungsten carbide (WC) as the material for the stylus. Experimental results show that, the tip ball roundness could amount to 2 μm. Since the tip ball is not easily observable by naked eyes, we designed a micro imaging system to observe the probing in real time. This system is created with modified commercial webcam and microscope. The general design of the touch trigger probe is combined the stylus and suspension structure. When the stylus touches workpiece, it can be determined the time of probe trigger by measuring the motion of suspension structure. The stylus machined by micro-EDM was very fragile and the stylus handle of the tip ball was very thin. Therefore, the stylus handle bends easily that would result in the large measurement error or stylus break when the stylus touched workpiece. In this study we designed a measuring probe using a small chuck and an electrical circuit to measure the probe trigger. When the stylus touches the workpiece, the parallel circuit will switch on immediately and pick up the voltage variation of the resistor. Because the transistor always turns ON, it can avoid the problems of excessive energy and electrical noise.

Paper Details

Date Published: 16 November 2011
PDF: 6 pages
Proc. SPIE 8321, Seventh International Symposium on Precision Engineering Measurements and Instrumentation, 83213A (16 November 2011); doi: 10.1117/12.905263
Show Author Affiliations
Chih-Liang Chu, Southern Taiwan Univ. (Taiwan)
Yi-Lin Chen, Southern Taiwan Univ. (Taiwan)
Tzu-Yao Tai, Southern Taiwan Univ. (Taiwan)
Yun-Hui Liu, Southern Taiwan Univ. (Taiwan)
Cheng-Hsin Chuang, Southern Taiwan Univ. (Taiwan)
Chin-Tu Lu, Southern Taiwan Univ. (Taiwan)

Published in SPIE Proceedings Vol. 8321:
Seventh International Symposium on Precision Engineering Measurements and Instrumentation
Kuang-Chao Fan; Man Song; Rong-Sheng Lu, Editor(s)

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