Research On Machine Vision Measurement Technology In Automatic Assembly Process Of Thermocouple

Monitoring subject wall heat temperature is very important to pulse wind tunnel transient heat flow detection. Due to the high dynamic pressure, high heat flow in the test environment, the flow of the temperature sensor is serious, so in order to control the cost and efficiency of the test, the appropriate temperature sensor is essential. Because of the simple structure, high temperature resistance and good repeatability, the coaxial thermocouple is a temperature sensor to meet the requirements of the front. At the same time, due to the needs of the test, the size of the coaxial thermocouple should be as small as possible. So in the production of this kind of temperature sensor, in order to ensure the quality of coaxial thermocouple, thermocouple between the electrodes need to do insulation protection. Therefore, in the process of the assembling of coaxial thermocouple, the uniformity of the insulating medium must be guaranteed, that is to ensure that one electrode is nested in the center of the other regular electrode. It can be seen that the thermocouple glue is an important part of the assembly.Currently, the irrigation glue process of coaxial thermocouple used in heat flow measurement is to take artificial manner. Insulation and efficiency of irrigation glue is not good because the manual mode is difficult to control. Obviously, that will affect the quality and using effect. Therefore, in this paper, we propose a machine vision measurement technology for thermocouple irrigation glue. The application of this method ensures the uniformity of the insulation between the electrodes of the thermocouple and improves the efficiency of the assembling, the measurement accuracy of thermocouple has been greatly improved also.This paper mainly studies and analyzes the method of machine vision measurement in the process of thermocouple irrigation glue, and analyzes and introduces the modules involved in the thermocouple filling system.Firstly, this paper introduced the advantage of machine vision measurement in irrigation glue and analyzed each part of the system. At the same time in order to facilitate the subsequent processing, we improved the clamping device. The device needs to measure the sleeve section from the forward and it can also keep the relative position unchanged for the two 45 degree angle shooting from the side vertical position, to get the distance between the object to be measured and the sleeve. Then, this paper focused on the research of machine vision measurement method used in the system. In determining the regularity of sleeve section(outer electrode), we used the methods of denoising, binarization, morphological closing operation and contour tracking method. After the feature extraction of contour, the paper described several methods to determine the round section and chose the method of Hough transform to screen size suitable sleeve. In the process of determining the distance between the core(inner electrode) and the sleeve, we compared the distance between pixel coordinate to judge and calculate the accuracy through the pixel coordinates record. Finally, we chose the fuzzy c-means to extract the appropriate profile and then done through the feature extraction and morphological processing to determine the position of the inner core whether is in the middle of the sleeve. The rationality of the method is verified by the results of the actual measurement. In summary, the machine vision measurement technology can realize the work requirements and meet the corresponding functions.