Needle bearings are required to be fixed in three directions, radial, axial and tangential, on the shaft and in the housing. The radial and tangential positioning is achieved by the tight fit of the bearing ring. The axial positioning is only used in a few cases. The axial position is generally limited by axial limit parts such as end caps and retaining rings. Within the clearance range.
When choosing a fit, you should pay attention to the following four points:
(1) The circumferential surface of the bearing ring should have good support and uniform force to reduce deformation, and fully exert the bearing capacity of IKO bearing.
(2) The ferrule cannot slide in the tangential direction in its mating surface, otherwise the mating surface will be damaged.
(3) The free end bearing must be compatible with the length change of the shaft and the housing bore, that is, it must have the ability to accommodate the axial position to swim within a certain range.
(4) It must be noted that the needle roller bearing is easy to install and disassemble, saving labor, time and money.
For heavy loads, the grease with a small penetration should be selected for high pressure, and the oil film strength and extreme pressure performance should be high. When selecting grease according to environmental conditions, calcium-based grease is not easily soluble in water and is suitable for drying and low moisture environments. Commonly used greases for IKO bearings include calcium-based greases, sodium-based greases, calcium-based greases, lithium-based greases, aluminum-based greases, and molybdenum disulfide greases. The amount of grease filled in the needle bearing is suitable for filling 1/2-1/3 of the inner space of the bearing. At high speeds, reducing the grease to 1/3 will increase the temperature rise.
The temperature of the bearing, generally the temperature outside the bearing can be inferred. If the oil hole can directly measure the outer ring temperature of the thin-walled bearing, it is more suitable. Usually, the temperature of the bearing rises slowly as the bearing starts to run, and reaches a steady state after 1-2 hours. The normal temperature of the needle bearing varies with the heat capacity, heat dissipation, speed and load of the machine. If the lubrication and installation parts are suitable, the IKO bearing temperature will rise sharply and abnormal temperature will occur. At this time, it is necessary to stop the operation and take necessary precautions.
The bearing is a kind of precision mechanical support component. The bearing user deeply hopes that the bearing mounted on the main machine will not damage and maintain its dynamic performance within the predetermined service period, but the objective facts are sometimes not satisfactory, sudden bearing failure accident. Will cause significant losses to users. Through a large number of bearing failure analysis studies, the short-life or premature loss of precision of needle roller bearings is due to material defects or improper manufacturing, but to a considerable extent, it is not installed and maintained in strict accordance with the requirements of bearing use. Or improper bearing damage or actual load exceeding the rated load of the thin-walled bearing itself causes abnormal damage to the IKO bearing.
Cracking and spalling of the bearing is caused by the cyclic load of the bearing, and the contact surface is prone to fatigue damage. Therefore, in order to improve the service life of the needle bearing, the bearing steel must have high contact fatigue strength.
Hardness is one of the important qualities of IKO bearing quality, and has a direct impact on contact fatigue strength, wear resistance and elastic limit. The hardness of the thin-walled bearing steel in the state of use generally reaches HRC61~65, so that the needle bearing can obtain high contact fatigue strength and wear resistance.
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