Tips for "All-staff preventive Maintenance Centered on inspection"
The bearings of the rolling mill are in operation
Perhaps for various reasons
This leads to premature damage of the bearing
Even under normal installation, lubrication and maintenance conditions
After a period of operation
Fatigue spalling and wear may also occur
It cannot work properly
The following are common faults and maintenance methods
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Common Fault 1: Fatigue spalling
The inner and outer raceways of a rolling bearing and the surfaces of the rolling elements roll relatively. Due to the effect of the shear load, cracks first form at a certain depth below the surface (at the maximum shear stress point), then spread to the contact surface, causing spalling pits on the surface layer, and finally develop into large-scale spalling. This is the fatigue spalling phenomenon. Fatigue spalling can cause an increase in impact loads, vibrations and noise during operation. Under normal circumstances, fatigue spalling is often the main cause of rolling bearing failure.
Common Fault 2: Wear and tear
Due to the intrusion of dust and foreign objects, surface wear will occur when the raceways and rolling elements move relatively. Poor lubrication will also accelerate the wear. The result of wear is an increase in bearing clearance, an increase in surface roughness, a reduction in bearing operation accuracy, and at the same time, an increase in vibration and noise. Therefore, to a certain extent, the amount of wear limits the service life of the bearing.
Common Fault 3: Plastic deformation
When bearings are subjected to large impact loads or static loads, or additional loads due to thermal deformation, or when very hard foreign objects invade, dents or scratches will form on the raceway surface. This will cause the bearing to generate severe vibration and noise during operation. Moreover, once there are indentations, the impact load caused by the indentations will further lead to the detachment of nearby surfaces.
So, how can we do a good job in the daily maintenance of rolling mill bearings?
Maintenance method one: Inspect the bearings during operation
According to the inspection standards, regularly listen to and observe the bearings. Listening is to use a listening rod with one end facing the axial end cover of the bearing and the radial shell of the bearing housing, and the other end pressed against the ear to listen for any impact sounds or mechanical friction sounds during the operation of the bearing. Observation involves checking the operating environment, installation location, vibration, lubrication conditions, etc., to see if there are any adverse working conditions. Use these methods to conduct periodic inspections of the bearings to determine whether they are in a normal state.
Maintenance Method Two: Precautions for Disassembling and assembling Bearings
After the rolls are removed, a cleaning agent can be used to clean the bearings thoroughly, dry them with compressed air, and then inspect the rolling elements, cages and raceways. Each time the rolls are disassembled or assembled, it is required to use compressed air to blow and inspect the oil, gas and lubricating oil passage of the roll seat to prevent blockage of the oil passage and poor lubrication.
Maintenance Method three: Post-disassembly inspection of the bearing
Check the bearing seal. Depending on the degree of wear, consider whether to replace it to prevent the bearing's service life from being affected due to poor sealing. If the bearing seal is poor and the emulsion enters the bearing, it will contaminate the lubricating oil system and affect the lubrication effect. If copper strips and copper powder enter the interior of the bearing, it will cause the lubrication conditions to be disrupted, resulting in foreign object wear on the surface of the bearing elements.
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