Better solution for bearing heating during use

High bearing temperature is a common and harmful failure of rotating equipment, which will reduce the service life of bearings and increase maintenance costs. When the temperature rises quickly and the temperature exceeds the standard, it may easily lead to unplanned shutdown or load reduction of the unit. The economic benefits have a great impact. Therefore, to quickly determine the cause of the failure and take appropriate measures to solve it is the guarantee of continuous and safe operation of the equipment.

Common causes of excessive bearing temperature

1. Improper refueling quantity, too little or too much lubricating oil

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, it will remain unchanged after reaching a certain point, and then it will gradually decrease.

2.The grease added to the bearings does not meet the requirements or is polluted

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, and the bearing box and bearing should be cleaned during maintenance, and the oiling pipeline should be inspected and cleared. Different types of grease are not allowed to be mixed. When 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.Insufficient cooling

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.

4. After confirming that the above problems do not exist, check the coupling alignment and bearings

The alignment of the coupling must meet the process standards. In the axial flow induced draft fan, hydraulic coupler, etc., the problem of thermal expansion of the equipment during operation should also be considered. 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 coupling. The bearing box expands and the bearing rises. Therefore, the motor should be higher when the timing is adjusted. The size of the reserve depends on the characteristics of the equipment and Depending on the temperature parameters during operation.

The inspection of bearings mainly includes the following:

1.The quality of the bearing

During the disassembly of the bearing box, first of all, 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 if it is above, the bearing should be replaced with a new one.

2. Bearing fit

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 suitable fit, 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.Adjusting the clearance of each bearing

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 operating conditions.