4. During the operation check and the trouble check operation, the inspection items include the rolling noise, vibration, temperature, and lubrication status of the bearing. The details are as follows: When an abnormal state is found during operation, refer to Table 2-8 above.
4.1 Rolling sound of the bearing The sounder is used to check the size and sound quality of the rolling sound of the running bearing. Even if the bearing is slightly peeled off, abnormal sounds and irregular sounds will be emitted, which can be distinguished by the sounder.
4.2 Bearing vibration The vibration of the bearing is very sensitive to the damage of the bearing. For example, peeling, indentation, rust, crack, wear, etc. will be reflected in the vibration measurement of the bearing. Therefore, by using a special bearing vibration measuring device (frequency analyzer, etc.) The magnitude of the vibration can be measured, and the specific situation of the abnormality cannot be inferred by the frequency. The measured values vary depending on the conditions of use of the bearing or the mounting position of the sensor. Therefore, it is necessary to analyze and compare the measured values of each machine in advance to determine the judgment standard.
4.3 Bearing temperature The temperature of the bearing, generally the temperature outside the bearing can be inferred. If the oil hole can directly measure the bearing outer ring temperature, it is more suitable. Usually, the temperature of the bearing rises slowly as the operation starts, and reaches a steady state after 1-2 hours. The normal temperature of the bearing varies with the heat capacity, heat dissipation, speed and load of the machine. If the lubrication and installation parts are suitable, the bearing temperature will rise sharply and abnormal temperature will occur. At this time, it is necessary to stop the operation and take necessary precautions. Based on a large amount of test data, Table 4-1 lists the average value of the outer ring temperature when the bearings are working in various machines for reference. Since the temperature is affected by lubrication, speed, load, and environment, the values in the table only indicate the approximate temperature range. The thermal sensor can be used to detect the working temperature of the bearing at any time, and automatically alarm or stop the occurrence of the burning shaft accident when the temperature exceeds the specified value.
4.4.1 Effect of bearing lubrication Lubrication has an important influence on the fatigue life of rolling bearings and friction, wear, temperature rise, vibration, etc. Without normal lubrication, the bearings cannot work. Analysis of the cause of bearing damage indicates that about 40% of bearing damage is associated with poor lubrication. Therefore, good lubrication of the bearings is an effective measure to reduce bearing friction and wear. In addition, the lubrication of the bearing also has various functions such as heat dissipation, rust prevention, sealing, and shock relief. The effect of bearing lubrication can be briefly explained as follows: a. Form a gap between the two rolling surfaces or sliding surfaces that are in contact with each other. The oil film separates the two surfaces, reducing friction and wear on the contact surfaces. b. When using oil lubrication, especially when using circulating oil lubrication, oil mist lubrication and fuel injection lubrication, the lubricating oil can take away most of the friction heat inside the bearing and effectively dissipate heat. c. When grease lubrication is used, foreign matter such as dust can be prevented from entering the bearing and sealing. d. Lubricants have the effect of preventing metal corrosion. e. Extend the fatigue life of the bearing.
4.4.2 Comparison of grease lubrication and oil lubrication The lubrication methods of bearings are roughly classified into grease lubrication and oil lubrication. In order to fully utilize the function of the bearing, it is important to use a lubrication method depending on the purpose of use reduction and use. Table 4-2 shows the advantages and disadvantages of grease lubrication and oil lubrication.
4.4.3 Grease Lubricating Grease is a lubricant consisting of a base oil, a thickener and an additive. When selecting, you should choose a grease that is very suitable for the conditions of use of the bearing. Due to the different trademarks, there will be great differences in performance, so you must pay attention when choosing. Commonly used greases for bearings include calcium-based greases, sodium-based greases, calcium-sodium-based greases, lithium-based greases, aluminum-based greases, and molybdenum disulfide greases. The amount of grease filled in the bearing is preferably 1/2-1/3 of the internal space of the bearing. It should be reduced to 1/3 at high speed. Excessive grease will increase the temperature rise.
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