Causes of bearing heating and solutions!
In our production process, we often encounter various problems, one of which is very troublesome but helpless, and that is the bearing heating problem. In fact, this problem often arises because we have not noticed some details. Now let me talk about the experience I have summed up on these issues in the past few years. First, you can quickly find the cause of the fever and take appropriate measures to ensure the safe and stable operation of the equipment. There are many reasons that cause the bearing temperature to be too high. Here are 7 common problems that I have organized for everyone. hope that it can help us. .
Lubrication has a significant impact on the service life of the bearing and friction, wear, vibration, etc. Good lubrication is a necessary condition to ensure the normal operation of the bearing. According to statistics, about 40% of bearing damage is related to poor lubrication.
: The effect of lubrication on bearings mainly includes
1) Prevent metal corrosion.
2) Prevent foreign objects from entering and play a sealing role.
3) Dissipate frictional heat to prevent the bearing temperature from rising too high.
4) Reduce friction and wear and extend bearing life.
The factors that usually cause poor bearing lubrication are:
1) Insufficient lubricant (grease).
2) The lubricating oil pipe is blocked by foreign matter, etc.
3) There is a problem with the quality of the lubricating oil (grease).
4) Lubricant (grease) is not added on time.
5) The lubricating oil (grease) contains impurities.
Bearings are important parts in various sizes of machinery. The working environment of some machines (such as crushers) is very dusty. When some fine dust enters the bearing housing that runs at high speed, it will cause deterioration of the lubricating oil or grease in the bearing housing, poor lubrication, and then wear of the bearing. The bearing continues to run under wear and tear. As the friction increases, the heat increases, which causes the bearing temperature to rise.
Improper installation is another important cause of bearing heating. Because the correct installation of the bearing has a direct impact on its life and the accuracy of the host, it is required that the centerline of the shaft and the bearing hole coincide when installing.
If the bearing is not installed correctly, the accuracy is low, the bearing has deflection, and a torque will be generated when it rotates, causing the bearing to heat or wear. In addition, bearings will also generate vibration and increase noise, which will also increase the temperature rise.
Insufficient cooling is usually manifested in: blocked pipes, inappropriate selection of cooler, poor cooling effect, etc.
Fouling and clogging of the cooler of the lubricating pipeline will cause the cooling effect to deteriorate, especially in summer production. This problem is particularly common. Individual manufacturers do not hesitate to increase or parallel coolers in series to enhance the cooling effect. The scale of the cooler is very serious, and the situation that the bearing temperature is too high and frequent alarms will be encountered in many production sites. The more effective treatment method is to scale the cooler before the summer.
For example, the difference in the process of correcting the coupling does not meet the requirements, the rotor has dynamic and static imbalances, the foundation rigidity is poor, the ground is weak, the rotation stall and surge are present. Some rotors are subject to the corrosion of the medium or the wear of solid impurities or the bending of the shaft, which will cause an unbalanced centrifugal force, which will cause the bearing to heat and vibrate, and the raceway will be seriously worn until it is damaged.
If the bearing is found to have severe fatigue peeling, oxidized rust, worn pits, cracks, or excessive noise that cannot be adjusted, if it is not replaced in time, it will cause the bearing to generate heat, abnormal sound, and vibration, which will affect the normal produce.
In addition, vibration caused by improper bearing disassembly and loose anchor bolts of the equipment will also cause indentation of the bearing raceways and rolling elements, and cracks in the inner and outer races of the bearing. During the running of the bearing, the inspection should be carried out according to the prescribed cycle.
Rolling bearing parts work in the form of point contact or line contact for a long time under high alternating contact stress. The accuracy, life and reliability of the host are largely determined by the bearings, so we must pay attention to inspection in the purchase and acceptance of bearings, using qualified high-quality products from regular manufacturers.
Now that we have found the problem, we will seek solutions to these problems. I think the solution to the problem is nothing more than the following:
1. Improper refueling, too much or too little grease
The bearing box should be refueled regularly in accordance with the requirements of the job. After the bearing is refueled, sometimes the temperature is high, mainly due to excessive refueling. At this time, the phenomenon is that the temperature continues to rise continuously. After reaching a certain point (generally about 10 ° C to 15 ° C higher than the normal operating temperature), it will remain unchanged and then gradually decrease.
2. When the added grease does not meet the requirements or is contaminated
The selection of lubricating grease is not suitable, it is not easy to form a uniform lubricating oil film, it is not possible to reduce the internal friction and wear of the bearing, the lubrication is insufficient, and the bearing temperature rises.
When different types of grease are mixed, a chemical reaction may occur, causing the grease to deteriorate and agglomerate, reducing the lubrication effect. Contamination of grease will also increase the temperature of the bearing. Dust will fall into the process of adding grease, which will cause grease pollution, resulting in deterioration of the grease inside the bearing housing, which will damage bearing lubrication and increase the temperature. Therefore, suitable grease should be selected. During the maintenance, the bearing box and bearing should be cleaned, and the oiling pipeline should be inspected and cleared. Different types of grease should not be mixed. If replacing other types of grease, the original grease should be cleaned first. Operation and maintenance Add grease regularly. Grease should be stored properly to prevent moisture and dust.
3. When the cooling is insufficient
Check whether the pipeline is blocked and whether the inlet temperature and return water temperature exceed the standard. If the cooler is not selected properly and the cooling effect is poor, it can't meet the requirements for use, it should be replaced in time or a new cooler should be installed in parallel. Axial flow induced draft fans should also check the insulation and tightness of the core cylinder.
4. When there is no problem with the above, check the coupling
The alignment of the coupling must meet the process standards. For example, the axial expansion fan, hydraulic coupler, etc. should also be used to correct the thermal expansion of the equipment during operation.
Due to the thermal expansion of the impeller side of the induced fan, the bearing box rises; the temperature increases during the operation of the hydraulic coupler. The bearing box expands and the bearing rises. Therefore, the motor should be higher when the timing is correct. Depending on the temperature parameters during operation.
Main points of daily bearing maintenance
Bearing maintenance is inseparable from daily maintenance, so where should we focus on during maintenance? I think there are the following points, I hope to help my friends.
First, check whether there is any bad condition such as deterioration, agglomeration, impurities, etc., which is an important basis for judging the cause of bearing damage.
Secondly, check the bearing for seizure and wear; check the surface finish of the bearing inner and outer rings, rolling elements and cages, as well as cracks, rust, peeling, pits, overheating and other defects, and measure whether the bearing clearance exceeds the standard; check The shaft sleeve is worn, pitted, peeled, and the bearing should be replaced with a new one if the above conditions exist.
When the bearing is installed, the cooperation between the bearing inner diameter and the shaft and the outer diameter and the housing is very important. When the fit is too loose, the mating surface will cause relative sliding, which is called creep.
Once the creep occurs, it will wear the mating surface, damage the shaft or the shell, and the wear powder will invade the inside of the bearing, causing heat, vibration and damage. When the interference is too large, the outer diameter of the outer ring becomes smaller or the inner diameter of the inner ring becomes larger, reducing the internal clearance of the bearing. In order to select a bearing suitable for the application, various factors such as the nature, size, temperature conditions of the bearing load, and the rotation of the inner and outer rings must be considered.
3. Adjustment of bearing clearance
If the bearing clearance is too small, the grease will cause the bearing to heat up due to the excessive shear friction loss in the clearance. At the same time, if the bearing clearance is too small, the amount of oil will be reduced. It is too late to take away the heat generated by the friction, which will further increase the bearing temperature .
However, if the clearance is too large, the dynamic characteristics of the bearing will be changed, causing the rotor to run unstable. It is therefore necessary to select verified bearing clearances for different equipment and conditions of use.
Thanks for watching! hope that it can help us!