Deep-hole inner diameter measuring system based on non-contact capacitance sensor

Abstract

A precise aperture measuring system of small deep holes with capacitance sensors is presented. Based on the working principle of non-contact capacitance sensors, influence of the edge effect of gauge head is studied, and one capacitance sensor for measuring the aperture of the small blind holes or through holes is introduced. The system is composed of one positioning device, one aperture measuring capacitance sensor, one measuring circuit, and software. This system employs visual CCD and two-dimensional micro-adjusting mechanism to realize the precise positioning. By LabView software this system is controlled to run automatically, to carry out calibration and automatic data collection, and to make data import into the database directly. Experiments proved that the diameter measurement range of the system can be 1.8 mm–7 mm, the resolution can be up to 5 nm–10 nm, the repeatability measurement standard deviation can be 0.05 μm–0.1 μm, and the measurement uncertainty can achieve 0.15 μm–0.3 μm. So the measuring system can realize the nanometer-level measurement.

Keywords

deep-hole measurement / non-contact / CCD / stepping motor / precise positioning

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