Time：2020.07.06 Source：Roller Bearings Suppliers
The correct use and common faults of cylindrical roller bearings
Cylindrical roller bearings are generally installed inside the mechanism, so it is inconvenient to check visually, only to make a rough judgment based on the fault phenomenon, and then disassemble and check.
The correct use of cylindrical roller bearings is a reliable guarantee to reduce bearing failures and extend bearing life. Its contents include correct installation and reasonable lubrication.
The following describes the use requirements and common failures and damages of cylindrical roller bearings.
The correct use of cylindrical roller bearings
1. Bearing disassembly
The bearings should be cleaned before installation. When installing, use special tools to press the auxiliary bearing straight and evenly. Do not strike with a hand hammer. It is especially forbidden to strike directly on the bearing. When the bearing seat ring and seat hole are loose, the seat hole should be repaired or the bearing should be replaced. Do not use the method of hitting pits or copper pads on the bearing mating surface. When disassembling the bearing, use a suitable puller to pull out the bearing, and do not hit the bearing with a chisel, hand hammer, etc.
2. Lubrication of bearings
Lubricants and greases are commonly used in cylindrical roller bearings. When the peripheral speed of the shaft is less than 4-5m/s, or the parts of the car that cannot be lubricated with lubricating oil, grease is used for lubrication. The advantage of grease lubrication is that the sealing structure is simple, the grease is not easy to be lost, and it is not greatly affected by temperature. Adding grease once can be used for a longer time.
Common failures of cylindrical roller bearings
The failure phenomena of cylindrical roller bearings are generally manifested in two types. One is that the temperature of the bearing installation part is too high, and the other is that there is noise during the operation of the bearing. WSBC cylindrical roller bearings NJ 313 EM bearings online , pls click here :
1. Bearing temperature is too high
When the mechanism is running, a certain temperature is allowed at the location where the bearing is installed. When touching the housing of the mechanism with the hand, it is normal to not feel hot, otherwise the temperature of the bearing is too high.
The reasons for the high bearing temperature are: the quality of the lubricating oil does not meet the requirements or deterioration, the viscosity of the lubricating oil is too high; the assembly of the mechanism is too tight (the gap is insufficient); the assembly of the bearing is too tight; the bearing race rotates on the shaft or in the housing; Large; broken bearing cage or rolling element, etc.
2. Bearing noise
Cylindrical roller bearings are allowed to have a slight running noise during operation. If the noise is too loud or there is abnormal noise or impact sound, it indicates that the bearing is faulty.
The reason for the noise of cylindrical roller bearings is more complicated. One is the wear of the matching surfaces of the inner and outer rings of the bearing. Due to this wear, the matching relationship between the bearing and the housing, and the bearing and the shaft is destroyed, causing the axis to deviate from the correct position, and producing an abnormal noise when the shaft moves at high speed. When the bearing is fatigued, the metal on the surface will peel off, which will also increase the radial clearance of the bearing and produce an abnormal noise. In addition, insufficient bearing lubrication, dry friction, and broken bearings can all produce abnormal sounds. After the bearing is worn and loose, the cage is loose and damaged, and there will also be abnormal noise.
Cylindrical roller bearing damage
When disassembling and inspecting cylindrical roller bearings, the faults and damage causes of the bearings can be judged according to the damage of the bearings.
1. Metal peeling off on the raceway surface
The rolling elements of the bearing and the raceway surfaces of the inner and outer rings are subjected to periodic pulsating loads, resulting in cyclically varying contact stress. When the number of stress cycles reaches a certain value, fatigue spalling occurs on the working surface of the rolling element or the inner and outer ring raceways. If the load of the bearing is too large, this fatigue will be exacerbated. In addition, the bearing is not installed correctly, the shaft is bent, and the raceway peeling phenomenon will also occur.Fatigue peeling of the bearing raceway will reduce the running accuracy of the shaft, and cause vibration and noise in the mechanism. WSBC cylindrical roller bearings SL18 3012 bearings online , hereby share bearing photos , pls click here :
2. Bearing burns
Burned bearings have tempered colors on their raceways and rolling elements. The causes of burns are generally insufficient lubrication, the quality of the lubricating oil does not meet the requirements or deterioration, and the bearing assembly is too tight.
3. Plastic deformation
Uneven pits appear on the contact surface of the raceway and roller of the bearing, indicating that the bearing is plastically deformed. The reason is that under the effect of a large static load or impact load, the local stress on the working surface exceeds the yield limit of the material. This situation generally occurs on bearings rotating at low speeds.
4. Cracks in the bearing race
The cause of the cracks in the bearing race may be over-tightness of the bearing, looseness of the foreign or inner ring of the bearing, deformation of the bearing of the bearing, and poor surface processing of the mounted bearing.
Excessively high temperature of cylindrical roller bearings is a relatively common phenomenon. The key is that we need to know the reasons for the heating of cylindrical roller bearings and the resulting phenomena, and then find solutions and solutions. The following is a brief introduction to the causes and solutions of the high bearing temperature.
Phenomenon of temperature increase of cylindrical roller bearing
(1) An alarm bell rings;
(2) Thermometer disc (expansion thermometer) black needle and yellow needle coincide or exceed yellow needle;
(3) Issue a fault signal that the bearing temperature has increased.
Reasons for temperature increase of cylindrical roller bearings
(1) Interruption of bearing cooling water
(2) Deterioration of oil quality
The oil itself is not clean or the oil is degraded during operation. For example, the increased moisture in the oil will cause the acidity of the oil to increase, which will reduce the lubricating effect of the oil.
Treatment of temperature rise of cylindrical roller bearing
When the bearing temperature rises, first determine whether it is malfunctioning, if it does rise, it should be treated as follows:
(1) Check the cooling water pressure, water flow and piping system are normal. If the water pressure is low, it may be that the filter is clogged. If it cannot be processed in time, it can be stopped for processing. When it is confirmed that it can work, it can be put into use again.
(2) The oil pressure of the governor should be checked. If the oil pressure is low, the cooling water hydraulic valve may be closed.
(3) Check whether there is abnormal noise in the bearing, and check whether the bearing swing is abnormal.
(4) Take an oil sample and observe whether the oil color has changed, and conduct a test to see if it has deteriorated. If deterioration is confirmed, it should be stopped and replaced with new oil.
(5) Check whether the oil level of the oil standard is normal. If it is abnormal, check whether the oil drain valve of the oil tank is tightly closed. If it is tightly closed, oil should be replenished. If the sealant is leaking oil, it should be shut down for treatment.
When we use cylindrical roller bearings, if it is found that the temperature is very high, then quickly stop the operation of the equipment, then find out the cause, and follow the solutions provided above, but it may be due to the cause of bearing heat Different, so the solution is also different, so we still have to deal with specific situations.