The service life of NTN rolling mill bearings is not only related to the quality of the bearings, but also closely related to their installation and use. Therefore, the technical requirements for bearing installation should be paid attention to, and the relevant operating regulations should be followed.
1. Preparation before installation
(1) Prior to installation, the mating surfaces of roller necks, bearing boxes, bearing rings, and bearing box covers should be carefully inspected to check whether their dimensions, shape position accuracy, and mating male covers meet the technical requirements of the design .
(2) The surface matching the bearing, the edges and burrs of the roller neck, bearing box hole and oil hole must be removed, and cleaned and coated with lubricant.
2. Installation of four-row cylindrical roller bearings
(1) Install the labyrinth ring (waterproof cover)
The cooperation between the labyrinth ring and the roll neck is generally a tight dynamic fit, and it needs to be gently tapped in with a copper rod during installation. The two surfaces of the labyrinth ring must be parallel and tightly fit the shaft shoulder and the inner ring of the bearing. NTN 6007LLBC3 bearings on line , pls click here :
(2) Install the outer ring
The outer ring of the four-row cylindrical roller bearing and the inner hole of the bearing housing are generally in a transitional fit. For smaller bearings, the outer ring and the whole of the roller and the cage can be gently tapped into the bearing housing with a copper rod. For larger bearings, you can use the lifting holes provided on the outer ring or the cage to lift the outer ring and outer ring components and install them vertically into the bearing box.
Marks Ⅰ, Ⅱ, Ⅲ, and Ⅳ on the end face of the outer ring are marks of the load zone. When it is installed and used for the first time, the direction of the rolling load should be aligned with the first mark. After cleaning and reinstalling, the rolling load can be aligned with the remaining marks in order to extend the service life of the bearing.
3. Installation of thrust (positioning) bearings
Thrust bearings include four-point angular ball bearings, double-row (single-row) angular ball bearings, two-way thrust tapered and cylindrical roller bearings. Recently, the company has also developed brake roller bearings.
When four-point angular ball bearings and double (single) row angular contact ball bearings are used as thrust bearings, they are not allowed to bear the load in the radial direction, so the inner bore of the bearing housing corresponds to the location where these bearings are assembled, and the diameter must be larger than the outer diameter of the bearing. The diameter is about 0.5 mm. Or the diameter of the roller is less than about 0.5 mm of the inner diameter of the bearing.
For four-point contact ball bearings, do not interchange the separation rings of the same model during installation to prevent changing the axial clearance at the factory.
Double-sided thrust tapered roller or double-sided thrust cylindrical roller bearings, the same circle, the bearing of the same model must not be interchanged, in order to prevent changing the axial clearance at the factory.
The end face of the thrust bearing inner ring must be pressed tightly when installed, and the axial direction must be locked. In order to avoid relative rotation on the roll neck, causing the wear and burn of the matching surface of the roll neck. NTN 5204ZZ bearings on line , pls click here :
When the axial force bearing of the brake roller is used, the axial positioning is performed through two bearing boxes, and the axial clearance is adjusted. When installing the bearing box, make sure that the inner and outer rings of the bearing are in close contact with the inner and outer rings of the main bearing. When fixing the bearing boxes on both sides in the axial direction of the frame, pay attention to eliminating the axial movement of the bearing boxes in the direction of the shaft end during the introduction of the bearing boxes on both sides into the frame.
4. Installation of four-row tapered roller bearings
The fit of the inner ring of the four-row tapered roller bearing and the roller neck is generally with a gap. When installing, first install the bearing into the bearing box, and then install the bearing box into the journal.
The outer ring of the four-row tapered roller bearing and the hole of the bearing box are also dynamically matched, and the outer ring is first installed into the bearing box. When leaving the factory, character symbols are printed on the outer ring, inner ring and inner and outer spacer rings, and must be installed into the bearing box in order according to the order of the character symbols during installation. It cannot be interchanged arbitrarily to prevent the change of bearing clearance.
Maintenance and monitoring of NTN rolling mill bearings
NTN bearings should be strengthened during maintenance and monitoring to extend their service life.
1. Keep the lubricating oil passage smooth, choose the type of lubricant according to the regulations, and refill the lubricant regularly with sufficient amount. Ensure that the rolling surfaces of the rollers and the sliding surfaces of the rollers and ribs maintain good oil wax lubrication.
2. Regularly check the sealing of the seals and replace damaged seals in time. Ensure the sealing performance of the bearing to prevent water and oxide scale from entering the bearing and the leakage of bearing lubricant.
3. In accordance with the actual situation of the company, actively carry out monitoring of the running status of bearings.
Noise monitoring: It should be a steady buzzing sound during normal operation. Regularly monitor and compare with the normal sound to find abnormal conditions in time.
Lubricant monitoring: Normal lubricant should be clear and clean. If the lubricant has become dirty, there will be worn particles or contaminants.
Temperature monitoring: When the temperature rises, the operation will be abnormal. The company has carried out temperature monitoring work and is willing to serve customers more extensively.
Establish a record card to record the number of days the bearing is used online, the amount of steel passed, and the maintenance and monitoring status, etc., and strengthen the management of the bearing's operating status.
Lubrication of NTN rolling mill bearings
1. The importance of lubrication
The lubrication of NTN bearings is to use oil film to separate the relative moving rolling surfaces from each other, so as not to fail due to excessive wear caused by rough point contact. If users can attach great importance to bearing lubrication technology, they can ensure that they can still maintain stable performance and rotation accuracy during a predetermined working life.
2. The amount of grease filled
The amount of grease filled should be one-third and one-half of the bearing and bearing housing space. If too much grease is added, the deterioration of the grease will be worsened or refined due to the stirring and sweeping heat. At high speeds it should only be filled to one third or less. When the rotation speed is very low, in order to prevent external heterophysics from entering the bearing, the housing space can be filled.
3. Grease replacement
The service life of the grease is limited, its lubricating performance gradually decreases during use, and wear and tear also gradually increases, so it must be replaced and replaced at certain intervals.
The replenishment period of the grease is related to the structure, speed, temperature and environment of the bearing, and should be determined according to the specific working conditions of the enterprise. When replacing grease, it should be noted that greases with different grades cannot be mixed. Mixing greases with different types of thickeners will destroy the structure and consistency of the lubrication. If greases with different grades must be replaced, the original After the grease has been completely removed, add new grease.