(1) Inspection during operation
The rolling mill bearings should be audited and the working temperature checked on a regular basis according to regulations.
You can use special equipment to monitor the stethoscope for listening or use a wooden rod or screwdriver to touch the bearing seat with one end and stick the other end to the ear for monitoring. Under normal circumstances, the bearing makes a buzzing sound. If there is a sharp clicking sound, it means that the lubricant is lacking. If the sound is normal after replenishing the lubricant, it can be judged that the lack of lubricant; if there is an irregular hitting sound, It means that foreign matter has entered the bearing or the bearing has been injured. In serious cases, the roller table may have peeled off.
The working temperature check is to measure the temperature on the bearing seat with a thermometer. If the temperature rise is too high, the internal clearance may be too small, or the bearing positioning may be incorrect.
(2) Inspection and maintenance after disassembly
According to the different working conditions of the rolling mill, it is stipulated that the rolling mill bearings should be thoroughly inspected and maintained every certain period. It can be combined with the roll change at the same time. Before the bearing is removed, the load area should be marked clearly. The outer ring should be rotated 90% when re-assembled °, change the outer ring to another loading area.
The bearing should be thoroughly cleaned during disassembly and inspection, and dried with dry compressed air. During the inspection, the inner and outer ring raceways, rolling elements, and cages of the bearing should be carefully inspected.
If there is dull wear on the raceway and rolling elements, the degree is not very serious, and it does not exceed the standard during the clearance detection, which can be regarded as normal wear and can continue to be used; if there is bright wear, it is proved to be insufficient lubrication. If the clearance test does not exceed the standard, you can strengthen the lubrication and continue to use it. If the clearance test exceeds the standard, you should replace the bearing; if a small amount of fatigue peeling (also called fatigue pitting), indicating that the fatigue life of the bearing has reached and the rolling mill bearings must be replaced.
If rust is found on the bearing parts during the inspection, it indicates that water or moisture has entered the bearing. It may be that the lubricating oil is inappropriate, indicating that the bearing seat is sealed. For oil mist and oil-air lubrication, it may also be that the compressed air contains water. If the rust is not serious, use a whetstone to clean the rust. If it is serious, replace the bearing.
The wear on the cage is usually caused by impurities or poor lubrication in the bearing.
After bearing maintenance, for grease-lubricated bearings, the removed grease must never be refilled into the bearing, and a new qualified grease must be replaced.
In addition, during the disassembly and maintenance of the bearing, the parts related to the assembly of the bearing should also be inspected to determine whether they meet the requirements of dimensional accuracy, smoothness, and contact rate specified in the drawings; especially the wall thickness tolerance of the bearing seat and the cylindricity of the inner hole, check various indicators such as the contact plane shape of the bearing seat and the archway, the contact rate, and the perpendicularity to the inner hole, and solve the problems in time.
If the above-mentioned regular inspection and maintenance work is in place, it can ensure that the rolling mill bearings are always working in the correct state, avoid further deterioration of potential problems in time, and can greatly extend the effective service life of the four-row cylindrical roller bearings for rolling mills.
Please check the Product Guide to select suitable bearings for your machinery.
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