Research On The Method Of Fine-Pitch Gear Measurement Base On Image Process

Fine-pitch gear is widely used in high precision instruments and meters, and its accuracy has direct influence on the instruments' operational performance and work life span, so the detection and measurement of fine-pitch gear is vital. Meantime, due to its own particularities, there are many difficulties in the fine-pitch gear's detection including low stiffness, easy distortion; short distance between two gears, difficult to adjust; high automation requirement on measurement system; difficulties of clamping and alignment from a great variety of micron gears; difficulties of arranging mechanical structure caused by the constraint of gears' size and volume. Currently, the automation of detection and measurement of fine-pitch gear is far from satisfaction both at home and abroad, and there is the shortage of testing instrument and equipment. In order to solve the problem of behindhand situation of detection method of fine-pitch gear, enhancing the study of fine-pitch gear's detection and development of testing instrument and equipment is becoming more important.In this paper, on the basis of the present research of fine-pitch gear's measurement, CCD image probe was mounted on the three-coordinates measuring machine to study non contact measurement method through the means of image processing with the purpose of the detection of fine-pitch gear. During the measuring procedure, we used the method of image processing to process the picture of fine-pitch gear, and then did several sets of data sampling of coordinates of involute flank profile's edge. According to the coordinates above, we finished the fit calculation about involute curve and calculated out some other parameters and mismachining tolerance with the help of base radius computed from fit results. The main contents in this paper are as follows:1 .Measurement and control system design of fine-pitch gear, including mechanical structure composition, kinetic control system, and measurement system.2.The study of digital image process method., including image enhancement, image segmentation and some other basic methods such as histogram modification, gray transformation, image filtration, image sharpen, edge detection, gray level threshold method, etc.3.Data processing of fine-pitch gear's measurement. According to the coordinates above, we finished the fit calculation about involute curve and calculated out some other parameters and mismachining tolerance with the help of base radius computed from fit results4.Error analysis of measurement of fine-pitch gear, we analyzed the measurement errors and the causes, and calculated the measurement errors finally.