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What are the maintenance of bearings?

Update:26-09-2021
Summary:

Maintenance Disassemble The disassembly of the bearing […]

Maintenance

Disassemble
The disassembly of the bearing is for regular maintenance, and it is carried out when the bearing is replaced. After disassembly, if you continue to use it, or if you need to check the condition of the bearing, the disassembly must be carried out as carefully as the installation. Pay attention not to damage the parts of the bearing, especially the disassembly of the interference fit bearing, which is difficult to operate.
It is also very important to design and manufacture disassembly tools according to needs. When disassembling, study the disassembly method and sequence according to the drawings, and investigate the matching conditions of the bearing to ensure that the disassembly operation is foolproof.
Disassembly of the outer ring For the outer ring with interference fit, several screws for extruding the outer ring are set on the circumference of the outer ring in advance, and the screws are tightened evenly while being disassembled. These screw holes are usually covered with blind plugs and separable bearings such as tapered roller bearings. Several cuts are set on the blocking shoulder of the shell. Use a pad to remove it with a press or gently tap it.
The disassembly of the inner ring can be the easiest to pull out with a press. At this time, pay attention to let the inner ring bear its pulling force. Furthermore, the pull-out clamps shown are mostly used, and no matter what kind of clamps, they must be firmly clamped to the side of the inner ring. For this reason, it is necessary to consider the size of the shoulder of the shaft, or study the processing of the upper groove at the shoulder in order to use the drawing fixture.
The oil pressure method is adopted for the inner ring disassembly of the large bearing. Oil pressure is applied through the oil hole provided in the bearing to make it easy to draw. For bearings with a large width, the hydraulic method and the drawing fixture are used together for disassembly operations.
The inner ring of cylindrical roller bearings can be disassembled by induction heating. It is a method to heat the part in a short time to expand the inner ring and then pull it out. Where a large number of these bearing inner rings need to be installed, induction heating is also used.

Cleaning
When disassembling the bearing for inspection, first make a record of the appearance with photography or other methods. In addition, confirm the amount of remaining lubricant and sample the lubricant before cleaning the bearing.
a. The cleaning of the bearing is divided into rough washing and fine washing, and a metal mesh rack can be placed at the bottom of the container in use.
b. When rough washing, use a brush in oil to remove grease or adhesions. At this time, if the bearing is rotated in oil, be careful that the rolling surface may be damaged by foreign matter.
c. When fine washing, slowly rotate the bearing in oil, and must be carried out carefully.
Commonly used cleaning agents are neutral non-water-containing diesel or kerosene, and sometimes warm lye etc. are used as needed. No matter what kind of cleaning agent is used, it must be filtered frequently to keep it clean.
After cleaning, immediately apply anti-rust oil or anti-rust grease on the bearing.

Inspection and judgment
In order to judge whether the removed bearing can be reused, it is necessary to check its dimensional accuracy, rotation accuracy, internal clearance, mating surface, raceway surface, cage, and sealing ring. Because large bearings cannot be rotated by hand, pay attention to checking the appearance of rolling elements, raceway surfaces, cages, rib surfaces, etc. The higher the importance of the bearing, the more careful inspection is required.
Causes of heating of rolling bearings and their elimination methods

Low bearing accuracy: select bearings with specified accuracy grades.

The spindle is bent or the box hole is not concentric: repair the spindle or box.

Poor lubrication: use the lubricating material of the specified brand and clean it properly.

Low assembly quality: Improve assembly quality.

Bearing inner and outer shell running ring: replace the bearing and related wear parts.

Axial force is too large: cleaning and adjusting the sealing ring gap between 0.2mm and 0.3mm, correcting the diameter of the impeller balance hole and verifying the static balance value.

Bearing damage: replace the bearing.

Custody
The bearings are coated with an appropriate amount of anti-rust oil and packed with anti-rust paper when they leave the factory. As long as the packaging is not damaged, the quality of the bearings will be guaranteed. However, for long-term storage, it is advisable to store it on a shelf 30cm above the ground under the condition that the humidity is lower than 65% and the temperature is about 20°C. In addition, the storage place should avoid direct sunlight or contact with cold walls.

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