Research On Micro Hole Diameter Measuring System With Capacitive Sensor

With the rapid development of modern science technology and manufacturing capability,micro-aperture devices are widely used in various industrial applications,and the higher and higher demands of the processing and detection accuracy of micro-aperture are proposed.Aperture is the most important geometric feature in hole characteristics and it is the primary means to determine the quality of the hole by aperture measuring.Generally,apertures of the micro-aperture devices have a significant impact on the function of products,but it is difficult to measure the apertures of microporous due to the limited measurement space.Therefore,micro-aperture precision measurement is an important research direction in the field of geometric precision measurement in the world.Based on the review about existing micro-aperture measuring methods and combined with the practical measuring needs,this paper proposes a contact measurement method via capacitance sensor.The main work of this paper is as follows:(1)This paper proposed a micro-aperture measuring method via capacitance sensor,in which the core measuring element is the capacitive sensing probe and achieved the function of measuring aperture by means of length measuring device.The working principle of the probe was also elaborated.The relationship between the lateral displacement and the quantity of capacitance change was obtained and the measuring sensitivity of probe was given.(2)This paper established the mechanics model of the probe and obtained analytical expression of the probe's lateral displacement.The finite element model of the probe is also established by ANSYS Workbench through which the static finite element simulation of main part of the probe was done.The analytical solution was consistent with the simulation value of FEA.The optimal structure size of probe parameters was obtained by means of the Taguchi experiment.The physical probe device was designed and made based on the work before.(3)Using coordinate measuring machine and micro-positioning platform as measurement platform,and the laser interferometerworked as length metering instrument,the micro-aperture measurement experiment system via capacitance sensor was set up in this paper.The measuring system was tested by measuring ?5 mmstandard ring gauge.The test results showed that the measurement error of the system was 9 ?m.At last,the analysis of the measuring error as well as the source of the error was given in the paper.