I. Types and characteristics of electronic yarn clearer Electronic yarn clearer is an important means to control harmful defects in yarn quality. It is often equipped on yarn conversion equipment, and the most common one is the winder, especially the automatic winder, which is the last quality control process and equipment for products of spinning enterprises and the first quality control process and equipment for raw materials of weaving enterprises. The working performance of electronic yarn clearer is directly related to the yarn quality control and the production efficiency of automatic winder, so the careful maintenance and timely maintenance of electronic yarn clearer is very important and necessary for the product quality and production efficiency of textile enterprises. According to the structure and working principle, there are two kinds of electronic yarn clearer: photoelectric and capacitive. At present, these two kinds of electronic yarn clearer are widely used in textile equipment such as winder and automatic winder. It's hard to say which is better or worse, only that each has its own advantages and disadvantages. We can compare these two kinds of electronic yarn clearer from the following aspects. First of all, these two yarn cleaners are mainly based on electronic technology to detect and remove yarn defects. Secondly, they generally have important components in structure, such as yarn signal detection, signal amplification and shaping, defect removal parameter setting, yarn removal action and so on. Thirdly, their purpose is to ensure that harmful yarn defects are controlled, thus improving yarn quality. However, there are many differences between these two yarn cleaners, mainly due to the differences brought by different circuit principles. Photoelectric electrostatic cleaning relies on luminous tube and receiving tube to detect the light blocking amount of yarn to reflect the lateral change and yarn defects, while capacitive electrostatic cleaning relies on detecting the capacitance change of yarn when it passes through the flat capacitor to reflect the yarn volume change and yarn defects. Due to different principles, there are obvious differences in yarn quality control and environmental impact in production practice, such as quality index, spinning material, temperature and humidity, dust, electronic sensing and so on. The first is the difference in quality index. Photoelectric cleaning is used to detect the value and change of the light-receiving surface area of yarn. Because the yarn is approximately cylindrical, but not all of them are standard cylindrical, it reflects the accurate change of the light receiving lateral area of the yarn, and the reflected yarn volume is only approximate. The advantage is that it is closer to people's feelings and impressions of yarn. It conforms to the user's visual perception and impression of the cloth made of photoelectric yarn. The disadvantage is that almost all yarn quality indicators are mainly capacitive detectors (produced by Hurst Company) in the spinning process, which may be different from the values detected by capacitive instruments that accurately reflect the yarn volume and changes. Capacitive electrostatic cleaning detects the capacitance change caused by yarn volume, so it can accurately reflect the value and change of yarn volume, while the value and change of yarn lateral area reflected by capacitive electrostatic cleaning are similar, and its advantages and disadvantages are just the opposite of photoelectric electrostatic cleaning. At present, there are both photoelectric electrostatic cleaning and capacitive electrostatic cleaning in the equipment of spinning enterprises, but relatively speaking, capacitive electrostatic cleaning accounts for the majority of users because the detection instruments of yarn quality indicators are mainly capacitive. Secondly, it is not difficult to analyze some differences between photoelectric electrostatic cleaning and capacitive electrostatic cleaning in production practice from their working principles and circuit characteristics. These two kinds of electrostatic cleaning are yarn detection and defect removal equipment mainly based on electronic instruments. The principle difference of sensors makes them have their own characteristics, advantages and disadvantages, mainly in the different influences on the external production environment and conditions. Because photoelectric electrostatic cleaning relies on light reception to detect the light receiving area of yarn, the production conditions are mainly affected by floating dust, light change, temperature and humidity. Flying dust will affect the emission and reception of light, the change of light will increase misoperation, and the temperature will cause instability and deviation of circuit performance. Higher humidity will make flying dust and dust easier to attach to the probe head of photoelectric electrostatic cleaning, which will aggravate the influence on the emission and reception of light by the probe head. Capacitive electrostatic cleaning is to judge the yarn volume by detecting the capacitance generated by the yarn through the plate capacitor, so all the factors that affect the capacitance value will affect it, including yarn material, temperature and humidity, flying dust, yarn speed and so on. The dielectric constant of different yarn materials will be different, temperature will affect the stability of circuit performance, humidity will affect the dielectric constant of yarn materials and the capacitance of probe, flying dust will also affect the capacitance of probe, and different yarn speeds will affect the friction static electricity between yarn and probe, which will also cause the change of capacitance. In the actual production process, the influence of these factors is very important, and the influence of different production environments and conditions on electrostatic cleaning is very different. For example, the influence of temperature, humidity and dust has a great relationship with the plant structure, air conditioning environment and ventilation conditions of different enterprises. For photoelectric electrostatic cleaning, the lighting mode will also affect the normal operation of electrostatic cleaning. For example, the photoelectric electrostatic cleaning of our company was exposed to the sun during the first phase of electrostatic cleaning detection, which led to a large number of electrostatic cleaning. Among the influencing factors of photoelectric electrostatic cleaning, according to the production experience, temperature is the main factor, especially in the alternating spring and summer and high temperature period in summer, which mainly shows the influence of high temperature and high temperature on the performance stability of electrostatic cleaning circuit board, especially on the voltage value of regulated power supply, resulting in voltage fluctuation and deviation, affecting the normal operation of electrostatic cleaning of the whole equipment, followed by the influence of flying dust on single spindle detection head. Too much flying dust is deposited on the photoelectric detector, which affects the accuracy of detection data and the automation of the detector. Second, the working principle of Lofi photoelectric electronic yarn clearer has been widely used by users, especially when domestic textile enterprises introduced ESPER-M automatic winder made by Italian Guan Mingsheng company in 1990s, it was widely used and achieved satisfactory results. The earlier photoelectric yarn clearer model is FR700, and it has been continuously improved. The photoelectric electric cleaning technology using microcomputer technology is more mature and advanced. The power board is improved, which improves the efficiency and reduces the calorific value and temperature rise. The process setting is changed to keyboard operation, and various parameters are displayed by LCD panel, accompanied by cutting curve display and setting. Later, the amplifier board was improved, and the circuit performance was improved by using single chip microcomputer, which simplified the circuit structure and reduced the failure rate. However, a large number of textile enterprises in China are still using the early photoelectric electronic yarn clearer, and because of its long use time, the failure rate is also rising, which has become an obstacle and hidden danger for production enterprises to improve product quality. The supply of many circuit boards has been in short supply, and it is broken, so it is impossible to replace and transform new boards. Only good maintenance and timely repair can prolong its service life, ensure its operation efficiency and improve yarn quality. Therefore, good maintenance and timely maintenance are more important and necessary. The leaders of our company have always attached great importance to this work, created a good environment and conditions for the photoelectric electrostatic cleaning machine to be well maintained and repaired in time, and accumulated some experience in use, maintenance and repair. In the past ten years, it has made great contributions to improving yarn quality, ensuring efficient operation of automatic winder and reducing maintenance cost. Now, these materials have been sorted out. Communicate with technicians of many production enterprises to improve the use effect and service life of photoelectric electronic yarn clearer and make greater contributions to the development of textile enterprises. Please give me advice if you can't reach it. To do a good job in the maintenance of photoelectric electronic yarn clearer, it is necessary to understand its working principle, especially the working principle closely related to maintenance, and know what it is and why it should be done, so as to be targeted, well documented and flexible in maintenance. After several years of continuous exploration and practice, I have tried my best to understand and verify its working principle from the schematic diagram of the circuit board, and guided the maintenance and repair work, and achieved certain results. However, since I am not a designer or manufacturer after all, the analysis of its principle is not comprehensive and accurate, and I pay more attention to practical work such as maintenance and repair, which is more in line with the use and demand of textile enterprises and easy to understand and guide the maintenance and repair work. From the structure of photoelectric electronic yarn clearer, it includes power transformer, regulated power board, cutter power board and setting board, and each spindle has an amplifier board and a probe. The common configuration is 60 amplification plates and 60 detection heads. The regulated power supply board provides stable working power supply and reference signal (25KHZ square wave) for the setting board, the amplifier board and the detector head, the cutter power supply board provides scissors power supply for the amplifier board and the detector head, the setting board is used to set the yarn cleaning process parameters, and automatically detect the yarn diameter together with the amplifier board and the detector head. At the same time, the process parameters are converted into various control voltage parameters, which become the basis and standard for the amplifier board and the detector head to control yarn defects. The function of the amplification board is to amplify and convert the yarn diameter signal detected by the detection head, compare it with various yarn defect indexes of the setting board, judge whether there are defects and types of defects in the spun yarn, and send the results to the single spindle board. After the cutting signal of the single-core board is converted by the amplifier circuit, the scissors of the detection head are controlled to cut the defects. The function of the probe is to cooperate with the amplification board to detect the yarn diameter signal by emitting and receiving light, and amplify it to the amplification board, and the scissors carried by it execute the yarn. The above is the composition of Lofi photoelectric yarn clearer and the function of each circuit board. It is very important to understand its working process and working principle in the next step. The work of photoelectric cleaning is mainly divided into two processes: automatic detection of yarn diameter and classification and removal of yarn defects. The former is mainly completed by the detection button on the setting board (an operation program on the microcomputer operation board). At this time, the setting board sets the set voltage to a specific value, so that the amplifying board is in the state of detecting the yarn diameter, the control of yarn defects is stopped, and the yarn diameter voltage in the operation process is transmitted to the setting board. After a period of detection (about 20-30 seconds), the setting board averages and stores the detected yarn diameter voltage parameters as the reference voltage of this kind of yarn, and then sets the voltage standard for cutting yarn defects according to the yarn cleaning process parameters, and sends it to the amplification board as the cutting standard for yarn defects. The reference voltage value of yarn diameter can still be accurately saved and will not be lost in the case of power failure, which is the automatic detection process of yarn diameter. After the automatic detection of yarn diameter is completed, the setting plate automatically returns to the standard control state of yarn defects. In this state, the amplifying plate receives the yarn diameter signal detected by the detector head according to the setting standard of the setting plate, and transmits it to the single spindle plate after amplification, comparison and classification, and then converts the cutting signal of the single spindle plate into the cutting action of the scissors of the pressure-controlled detector head to complete the cutting of yarn defects and ensure the stability and improvement of yarn quality. From the above analysis, it can be seen that the power board is the working basis of Luofei electric cleaning composition. The setting board collects and stores the yarn diameter signal and converts it into the control standard of electronic yarn cleaner. The amplification board and the detection head complete the removal and control of yarn defects, and these circuit boards work together to complete the electric cleaning task. Electronic yarn cleaner is an adjustable instrument, which mainly shows that the cutting curve is determined by setting process parameters to meet the different requirements of different users for yarn. At the same time, the circuit parameters of the detector and amplifier can be adjusted and optimized, which means that its working state is different from other equipment and instruments, and it can be divided into three types: accurate operation, normal operation and fault state. For textile production enterprises, electronic yarn clearer affects the quality and output of yarn at the same time. Accurate working conditions not only help to strictly control yarn defects, but also help to improve the production efficiency of automatic winder. On the contrary, it will have adverse effects. Too many missing cuts will affect the removal of yarn defects, which is extremely unfavorable to quality. Although too much wrong cutting can ensure yarn quality, it will affect the production efficiency of automatic winder, increase the number and burden of joints, and increase equipment wear and failure. Increasing the number of coils and too many joints will increase the small yarn defects at the joints. In fact, in the process of exploring its working principle and accumulating practical production experience, I found that the wrong cutting and missing cutting of electric cleaning exist at the same time, only for different yarn defects, because most of the yarn defects are related to excessive yarn diameter, such as neps, short thickness and long thickness, and the details are related to excessive yarn diameter. In actual production, the former accounts for the absolute number of yarn defects. The control parameters of yarn defects are all obtained by amplifying and converting the detected yarn diameter. When the detected yarn diameter is thicker than the actual yarn diameter, large-diameter defects will be cut by mistake, while detailed defects will be missed. On the contrary, when the detected yarn diameter is smaller than the actual yarn diameter, large-diameter defects will be missed, and detail defects will also be missed. The difference between the yarn diameter detected by a single spindle and the yarn reference diameter is the root cause of false cutting and missing cutting, and the yarn diameters detected by the two may be deviated due to different circuit parameters. Only by ensuring the accuracy of yarn diameter can we ensure the elimination and reduction of false cutting and missing cutting, and to ensure this, we must ensure the accuracy of electrical parameters of each circuit board of electronic yarn clearer, including the accuracy and stability of power supply board voltage. The accuracy and rationality of the process parameters of the setting plate, and the most important thing is the accuracy and unity of the circuit parameters of the detection head and the amplification plate, because they are the basis for setting the plate to detect the yarn reference diameter, and are also the main body of yarn defect control, which is related to the accuracy and reliability of the electronic yarn clearer. Therefore, it is necessary to do a good job in maintaining the electrostatic cleaner, and improve the working state of the electrostatic cleaner from normal to accurate operation, so as to ensure the requirements of yarn defect control and efficient production. The three working states of Rofid electronic yarn clearer have been reflected in its operating instructions. In order to make it work in a good state, Rophy Company has equipped users with a special tester. There are three circuit technical parameters in the manual, which stipulate that the voltage deviation between positive and negative 12V is 0.20V, that is, it is required to be between positive and negative11.80-12.2v. The second item is the voltage value of the yarn diameter signal F.sig when the standard yarn sample (0.5mm steel wire) is put into the tester. The third item is that the feedback voltage Ureg is between 6.2 and 6.8V. The experience in actual production shows that when these three circuit parameters exceed a certain range of the above standards, obvious faults may not necessarily occur. In fact, we found mistakes in production. 3.60-4.40v； 5.80-7.80V, so it can be seen that these three state values may have exceeded the required circuit parameters without obvious faults, leading to the wrong cutting and missing cutting of the electronic yarn clearer, which seriously affected the yarn quality and the production efficiency of the equipment. The positive and negative voltage of 12V is the working voltage provided by the power board, and its instability and inaccuracy will cause the deviation of the whole electric cleaning system, so it has a great influence. The latter two items are important and key circuit parameters of amplifier and detector, which are directly related to the accurate removal and operation of yarn defects. In particular, the reference voltage value of yarn diameter directly determines the accuracy of electronic yarn clearer, and the feedback voltage determines the ability of a single electric cleaning circuit to eliminate the performance change of internal circuit and the influence of external environment, making it more accurate and stable. In fact, all the above parameters have certain accurate values. Only by ensuring that these circuit parameters are stable at accurate values can the electrostatic precipitator work in an accurate state. For example, the regulated voltage value is adjusted to plus or minus 12. 15V. This is because the automatic winder consists of dozens of single spindles, and the voltage difference from the first single spindle to the last single spindle before and after voltage adjustment is about 0.30V, so the voltage of the headstock is 12. 15V. The middle voltage is 12.00V, and the rear voltage is 1 1.85V, which basically keeps the voltage balance and reduces the adverse impact of voltage deviation on the whole electric vacuum cleaner. Compared with the voltage parameter (11.50-12.50 v) required in the original operating rules, the voltage value of yarn diameter signal is adjusted to 4.00±0.20v v when the sample steel wire is put in, which can ensure that the deviation rate of yarn cutting curve is controlled at 1%, while in the original operating rules. It can make up and eliminate the adverse effects caused by various factors stably and effectively, and ensure the stability and accuracy of electrostatic cleaning. The above circuit technical parameters can be called precise operation state, while the circuit technical parameters required by the operating instructions can be called normal operation state. It is worth mentioning that the fault state is not exactly the same as the usual fault, which includes the operation state with inconspicuous fault phenomenon and the state with obvious fault phenomenon that even leads to production difficulties. The former is also called fault state because the yarn defect deviation controlled by electric cleaning has exceeded the allowable limit, which poses a great threat to the yarn quality index. The effective means to deal with the fault state is repair, and the effective means to achieve and ensure the accurate operation state is careful implementation.