1. Correct use of IKO needle roller bearings
(1) Disassembly and assembly of the bearing
The bearing should be cleaned before installation. When installing, use special tools to press in the auxiliary bearing straight and evenly. Do not strike with a hammer. It is especially forbidden to strike directly on the bearing. When the bearing race is loose with the seat hole, the seat hole should be repaired or the bearing should be replaced. Do not use pitting or pad copper on the bearing mating surface. When disassembling the bearing, use a suitable puller to pull the bearing out, and do not knock the bearing with a chisel, hand hammer, etc.
(2) Lubrication of bearings
Commonly used lubricants for IKO needle roller bearings are lubricating oil and grease. When the peripheral speed of the shaft is less than 4-5m/s, or the parts on the car that cannot be lubricated with lubricating oil, grease lubrication is used. The advantages of grease lubrication are that the sealing structure is simple, the grease is not easy to lose, and it is not affected by temperature. It can be used for a longer time with one grease.
Two problems should be paid attention to when using lubricating grease. One is to select the appropriate brand of lubricating grease according to the requirements of the car manual. For example, it is not appropriate to use nano-based grease for automotive water pump bearings because of its poor water resistance. The second is to add a proper amount of grease to the bearing. Generally, it is only suitable to fill 1/2-l/3 of the bearing cavity. Too much is not only useless, but also increases the running resistance of the bearing, causing it to heat up and heat up. Special attention should be paid to automobile wheel bearings. "Empty hub lubrication" should be promoted, that is, only an appropriate layer of grease should be applied to the bearing. Otherwise, it will not only waste and poor heat dissipation, but will also cause the grease to be heated and overflow, which may affect Braking performance.
The advantages of lubricating oil are low frictional resistance and heat dissipation. It is mainly used for bearings with high speed and high working temperature. The brand of lubricating oil should be selected according to the requirements of the car manual, and replaced in time after the car maintenance cycle. After the old oil is discharged, the mechanism should be cleaned before adding new oil. The fuel should be added to the specified line or flush with the fuel filler. (It depends on the specific structure and requirements of the car), no more.
2. Common faults of IKO needle roller bearings
IKO needle roller bearings generally have two failures, 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.
(1) The bearing temperature is too high
When the mechanism is in operation, the part where the bearing is installed is allowed to have a certain temperature. When touching the housing of the mechanism by hand, it is normal to not feel hot, otherwise it indicates that the bearing temperature is too high.
The reasons for the excessively high bearing temperature include: the quality of lubricating oil does not meet the requirements or deterioration, the viscosity of lubricating oil is too high; the mechanism assembly is too tight (insufficient clearance); the bearing assembly is too tight; the bearing race rotates on the shaft or in the housing; Large; the bearing cage or IKO needle roller bearing body is broken, etc.
(2) Bearing noise
IKO needle roller bearings are allowed to have a slight running noise during work. If the noise is too loud or there is abnormal noise or impact, it indicates that the bearing is faulty.
IKO needle roller bearings have more complicated reasons for noise. One is the wear of the mating surfaces of the inner and outer rings of the bearing. Due to this kind of 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 abnormal noise occurs when the shaft is moving at high speed. When the bearing is fatigued, the metal on its surface will peel off, which will also increase the radial clearance of the bearing and produce abnormal noise. In addition, insufficient bearing lubrication, formation of dry friction, and bearing breakage will cause abnormal noise. After the bearing is worn and loosened, the cage is loosened and damaged, and abnormal noise will also be produced.
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3. Damage of IKO needle roller bearings
When the IKO needle roller bearing is disassembled and inspected, the fault and the cause of the damage can be judged according to the damage of the bearing.
(1) The metal peeling off the surface of the raceway
The IKO needle roller bearing body and the inner and outer ring raceways are all subjected to periodic pulsating loads, resulting in periodic contact stresses. When the number of stress cycles reaches a certain value, fatigue spalling occurs on the working surface of the IKO needle roller bearing body or the inner and outer ring raceways. If the bearing load is too large, this fatigue will increase. In addition, if the bearing is installed incorrectly and the shaft is bent, the raceway will peel off.
Fatigue spalling of the bearing raceway will reduce the running accuracy of the shaft and cause vibration and noise to the mechanism.
(2) Bearing burns
The burnt bearing has a tempered color on its raceway and IKO needle roller bearing body. 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
The uneven pits on the contact surface between the raceway and the roller of the bearing indicate that the bearing is plastically deformed. The reason is that the local stress on the working surface of the bearing exceeds the yield limit of the material under the action of a large static load or impact load. This situation generally occurs on a bearing that rotates at a low speed.
(4) Cracks in the bearing races. The causes of cracks in the bearing races may be that the bearing is too tightly fitted, the outer ring of the bearing or the inner ring is loose, the bearing housing is deformed, and the surface on which the bearing is installed is poorly processed.
(5) The reason for the cage cracking is insufficient lubrication, the IKO needle roller bearing body is broken, the seat ring is skewed and so on.
(6) The metal of the cage adheres to the IKO needle roller bearing body. The possible cause is that the IKO needle roller bearing body is stuck in the cage or insufficient lubrication.
(7) The raceway of the seat ring is severely worn, which may be caused by foreign matter falling into the seat ring, insufficient lubricating oil or improper lubricating oil grade.