·The bearing temperature is too high, similar to the abnormal situation of “fever”. It is a common and harmful failure of rotating equipment. If the cause is unknown and improperly handled, it will often get half the result with half the effort, which will reduce the useful life of the bearing, increase the maintenance cost, and even cause the bearing to burn out.
· Therefore, to quickly determine the cause of the failure and take appropriate measures to solve it is the guarantee for the continuous and safe operation of the equipment.
·The bearing temperature is too high-here is the culprit
·There are many reasons that cause the bearing temperature to be too high, and we have sorted out several common problems for everyone.
-Poor lubrication
·Lubrication has an important influence 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 main effects of lubrication on bearings include:
-1) Prevent metal corrosion -2) Prevent foreign matter from intruding and play a sealing role 3) Discharge frictional heat to prevent excessive temperature rise of the bearing-4) Reduce friction and wear, and extend bearing life
·The longer the rotation time, the better the quality? Facts have proved to be related to the lubricating oil
The factors that usually cause poor bearing lubrication are:
·1) Insufficient lubricating oil (grease)
·2) The lubricating oil pipe is blocked by foreign matter, etc.
·3) The quality of lubricating oil (grease) is problematic -4) The lubricating oil (grease) is not added on time -5) The lubricating oil (grease) contains impurities
.Bearing wear
·As an important part, bearings are used in various large and small machines. Some machines (such as crushers) have a lot of dust in the working environment. When part of the fine dust enters the high-speed bearing housing, it will cause lubricating oil or grease in the bearing housing. Deterioration, poor lubrication, and then wear and tear on the bearing. Bearings continue to run in a worn state, due to increased friction and heat increase, resulting in an increase in the temperature of the bearing.
·Improper installation
·Improper installation is another important cause of bearing heating. Because the bearing is installed correctly or not, it has a direct impact on its life and the accuracy of the host, so the center line of the shaft and the bearing hole must be coincident during installation.
·If the bearing is installed incorrectly, the accuracy is low, and the bearing has deflection, torque will be generated during rotation, which will cause the bearing to heat up or wear. In addition, the bearing will generate vibration, increase the noise, and increase the temperature rise.
-Insufficient cooling
·Insufficient cooling is usually manifested as: pipeline blockage, improper selection of cooler, poor cooling effect, etc.
-▲Cooler
·Scaling and clogging of the cooler of the lubrication pipeline will cause the cooling effect to deteriorate, especially in summer production. This problem is especially common (public number: pump housekeeper). Individual manufacturers do not hesitate to increase or parallel series coolers to enhance the cooling effect.
·Severe scaling of the cooler and frequent alarms for excessively high bearing temperature are encountered in many production sites. A more effective solution is to pickling and descale the cooler before the beginning of summer each year.
·Big vibration
·For example, the coupling alignment process does not meet the requirements, the rotor has dynamic and static imbalance, the foundation rigidity is poor, the foot is virtual, rotating stall and surge.
·▲Coupling
·During the operation of some rotors, due to the corrosion of the medium or the abrasion of solid impurities, or the bending of the shaft, unbalanced centrifugal force will be generated, which will cause the bearing to heat and vibrate, and the raceway will be severely worn until it is destroyed.
Check and replace not in time
·If the bearing is found to suffer from fatigue peeling, oxidation, corrosion, 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 noise, vibration, etc., which will affect the normal Production.
In addition, vibration caused by improper bearing disassembly and loose equipment anchor bolts can also cause indentation on the bearing raceway and rolling elements, and cracks in the inner and outer races of the bearing. During the operation of the bearing, the inspection should be carried out according to the specified period.
Poor bearing quality
·Rolling bearing parts work for a long time under high alternating contact stress in the form of point contact or line contact. The accuracy, life and reliability of the main engine are largely determined by the bearing. Therefore, it is necessary to pay attention to the inspection during the purchase and acceptance of the bearing, and use qualified and high-quality products from regular manufacturers.
Improper bearing selection
·Pay attention to the limit speed and load capacity of the bearing when selecting the bearing. It cannot be used with over-speed or over-load, as this will only shorten the service life of the bearing, and the gain will not be worth the loss.
·Bearing cooling has a coup
·When the bearing temperature is high, the problems should be solved first from the following aspects.
·When the amount of oil is improper, too much or too little lubricating grease:
·The bearing box should be oiled regularly in accordance with the requirements of the work. High temperature sometimes occurs after the bearing is refueled, mainly due to excessive refueling.
·At this time, the phenomenon is that the temperature continues to rise, after reaching a certain point (usually about 10℃~15℃ higher than the normal operating temperature), it will remain unchanged, and then it will gradually decrease.
When the added grease does not meet the requirements or is contaminated:
·Inappropriate selection of lubricating grease, it is not easy to form a uniform lubricating oil film, can not reduce the internal friction and wear of the bearing, insufficient lubrication, bearing temperature rise.
·When different types of grease are mixed, a chemical reaction may occur, causing the grease to deteriorate, agglomerate, and reduce the lubricating effect.
·Lubricating Grease
·Contaminated grease will also increase the temperature of the bearing. Dust will fall into the grease during the process of adding grease, causing grease pollution, resulting in deterioration of grease in the bearing box, destroying the lubrication of the bearing, and increasing the temperature.
·Therefore, suitable grease should be selected, the bearing box and bearings should be cleaned during the maintenance, and the fueling pipeline should be checked and dredged. Different types of greases are not allowed to be mixed; if you change other types of grease, the original grease should be cleaned up; operation and maintenance Grease is added regularly in the medium, and the grease should be properly stored for moisture and dust prevention measures.
.When the cooling is insufficient:
·Check whether the pipeline is blocked, whether the inlet oil temperature and the return water temperature exceed the standard.
·If the cooler is not selected properly, the cooling effect is poor, and cannot meet the requirements of use, it should be replaced in time or a new cooler should be installed in parallel. The axial flow induced draft fan should also check the insulation and tightness of the core tube.
.When there is no problem in the above aspects, check the coupling:
·The alignment of the coupling must conform to the process standard. The thermal expansion of the equipment during operation should also be considered when aligning axial-flow induced draft fans and fluid couplings.
·The bearing housing rises due to thermal expansion on the impeller side of the coupling alignment; the temperature rises during the operation of the fluid coupling, the bearing housing expands, and the bearing rises. Therefore, the motor should be higher when alignment, and the size of the reserved amount should be based on It depends on the characteristics of the equipment and the temperature parameters in operation.
·What should be paid attention to in bearing inspection·Bearing quality
·First of all, check whether the lubricating grease has bad conditions such as deterioration, agglomeration, impurities, etc. This is an important basis for judging the cause of bearing damage.
·Secondly, check the bearing for bite damage and wear; check the surface finish of the bearing inner and outer rings, rolling elements, and cage, as well as whether there are defects such as cracks, rust, peeling, pits, overheating and discoloration, and measure whether the bearing clearance exceeds the standard; Check whether the shaft sleeve is worn, pits, or peeling. If any of the above conditions, replace the bearing with a new one.
Bearing fit
·When the bearing is installed, it is very important to match the inner diameter of the bearing with the shaft, outer diameter and the housing. When the fit is too loose, relative sliding of the mating surface will be called creep.
·Once creep occurs, it will wear the mating surface and damage the shaft or housing, and the wear powder will invade the inside of the bearing, causing heat, vibration and damage.
·If the interference is too large, the outer diameter of the outer ring will decrease or the inner diameter of the inner ring will increase, reducing the internal clearance of the bearing.
·In order to select a suitable bearing, various factors such as the nature, size, temperature condition of the bearing load, and the rotation of the inner ring and outer ring must be considered.
·Adjustment of bearing clearance
·If the bearing clearance is too small, due to the excessive shear friction loss of the grease in the clearance, it will also cause the bearing to heat up. At the same time, the clearance is too small, the oil volume will be reduced, too late to take away the heat generated by friction, which will further increase the temperature of the bearing. Rise. However, excessive clearance will change the dynamic characteristics of the bearing and cause unstable operation of the rotor. Therefore, it is necessary to select the verified bearing clearance for different equipment and use conditions
Post time: Jul-16-2021