Maintenance of bearings

Disassembly:

Bearing disassembly is a regular maintenance task, and bearing replacement is required. After disassembly, if you continue to use it, or if you need to check the condition of the bearing, disassembly should be carried out with the same care as during installation. Be careful not to damage the various parts of the bearing, especially the disassembly of interference fit bearings, which is difficult to operate.

It is also important to design and build disassembly tools according to your needs. During disassembly, study the disassembly method and sequence according to the drawings, and investigate the matching conditions of the bearings to ensure a foolproof disassembly operation.

Disassembly of the outer ring: For the outer ring with an interference fit, set several screws for extruding the outer ring screw on the circumference of the casing in advance, and tighten the screws evenly while disassembling. These screw holes are usually covered with blind plugs, separable bearings such as tapered roller bearings, and several cuts are set on the housing shoulder. Use spacers to disassemble with a press or tap lightly to disassemble.

To disassemble the inner ring, it is easiest to use a press to pull it out. At this time, attention should be paid to allowing the inner ring to withstand its pulling force. Furthermore, the pull-out clamp shown is mostly used. No matter what kind of clamp, it must be firmly stuck on the side of the inner ring. For this reason, it is necessary to consider the size of the shaft shoulder, or study the processing of an upper groove at the shoulder to facilitate the use of a drawing fixture.

The inner ring of large bearings is disassembled using the oil pressure method. Oil pressure is applied through the oil hole provided in the bearing to make it easy to pull out. For large-width bearings, the hydraulic method and the drawing fixture are used together for disassembly.

Induction heating can be used to disassemble the inner ring of cylindrical roller bearings. This is a method of heating a local area in a short period of time to expand the inner ring and then drawing it. Induction heating is also used where a large number of such bearing inner rings need to be installed.

Cleaning:

When disassembling the bearing for inspection, first record the appearance using photography and other methods. In addition, confirm the amount of remaining lubricant and sample the lubricant before cleaning the bearings.

a. The cleaning of bearings is divided into rough cleaning and fine cleaning, and a metal grid can be placed at the bottom of the container used.

b. During rough cleaning, use a brush in oil to remove grease or sticky matter. At this time, if the bearing is rotated in oil, be aware that the rolling surface may be damaged by foreign matter, etc.

c. When fine cleaning, slowly rotate the bearing in the oil and do it carefully.

The commonly used cleaning agents are neutral non-aqueous diesel or kerosene, and warm alkali solution is sometimes used as needed. No matter which cleaning agent you use, filter it frequently to keep it clean. After cleaning, immediately apply anti-rust oil or anti-rust grease to the bearings.

In order to judge whether the removed bearing can be reused, it is necessary to focus on checking its dimensional accuracy, rotation accuracy, internal clearance, mating surface, raceway surface, cage and sealing ring. Since large bearings cannot be rotated by hand, pay attention to the appearance of rolling elements, raceway surfaces, cages, rib surfaces, etc. The more important the bearing, the more careful inspection is required.