Maintenance and maintenance of bearings

Maintenance and maintenance of bearings

1. Regular inspection

In order to make the bearing fully play and maintain its proper performance for a long time, it is necessary to do regular maintenance (periodic inspection). It is very important to improve productivity and economy by properly detecting failures early and preventing accidents before they happen.

1.1 Cleaning

When the bearing is removed for inspection, first use photography and other methods to make a record of its appearance. Also, confirm the amount of remaining lubricant and sample the bearing for the lubricant.

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

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

c. During fine cleaning, turn the bearing slowly in the oil, which must be done carefully.

The cleaning agent usually used is neutral water-free diesel or kerosene, and sometimes warm lye is used as needed. No matter what kind of cleaning agent filter is used to keep it clean. After cleaning, apply anti-rust oil or anti-rust grease to the bearing immediately.

1.2 Inspection and judgment

1.2.1 Bearing fault identification method

Maintenance and maintenance of bearings It is very important to improve productivity and economy to identify or predict whether there is a fault in a running bearing without disassembly inspection. The main law is as follows:

a. Recognition by sound

Recognition by sound requires a lot of experience. Must be sufficiently trained to be able to recognize bearing sounds from non-bearing sounds. For this work to be carried out by a special person. The sound of the bearing can be clearly heard by attaching a listener or a listening stick to the shell.

b. Identify by working temperature

This method is a comparative identification method, which is limited to occasions where the running state does not change much. For this, continuous recording of the temperature is necessary. There is only an increase in temperature, but also irregular changes.

c. Identification by the state of the lubricant

The lubricant is sampled and analyzed, and judged by whether the degree of contamination is mixed with foreign matter or metal powder. This method is especially effective for bearings that cannot be observed closely.

1.2.2 Inspection of bearings

Check the disassembled bearings during the regular maintenance of the equipment, the operation inspection and the replacement of peripheral parts, so as to judge whether the bearings can be used again. It is necessary to carefully investigate and record the removed bearings and their appearance. In order to clarify and investigate the remaining amount of lubricant, clean the bearings in a sampling manner.

Secondly, check the raceway surface, the condition of the rolling surface and the mating surface, and the wear state of the cage for damage and abnormalities. To judge whether the bearing can be used again, it is necessary to check the results after considering the degree of bearing damage, machine performance, importance, operating conditions, and inspection cycle. Countermeasures. In addition, if there are several defects in the inspection results, the bearing can no longer be used, and a new bearing needs to be replaced.

a. There are cracks and debris in any of the inner and outer rings, rolling elements, and cages.

b. Any one of the inner and outer rings and rolling elements is peeled off.

c. The raceway surface, ribs, and rolling elements are obviously stuck.

d. The cage is severely worn or the rivets are loose.

e. The raceway surface and rolling elements are rusted and scratched.

f. There are obvious indentations and marks on the rolling surface and rolling elements.

g. There is creep on the inner diameter surface of the inner ring or the outer diameter of the outer ring.

h. Severe discoloration due to overheating.

i. The sealing ring and dust cover of the grease-sealed bearing are severely damaged.

2. Stop inspection

It is very important to check the bearing seal regularly to maintain the bearing in good condition. The favorable inspection time is arranged in the regular shutdown inspection plan and knowing the type of bearing and having bearing spare parts is usually by means of inspection work.

2.1 It is very important to keep the bearings and lubrication clean.

Clean the surface of the machine before inspection, and then disassemble the parts around the bearing. The oil seal is a very fragile part, so it needs to be carefully disassembled, cut, and then carefully inspect the oil seal and its surrounding parts. If there are bad symptoms, be sure to replace it, and the bad oil seal will damage the serious equipment. shutdown.

2.2 Check lubricant

Rub a little lubricant between your fingers, feel for contamination if present, or apply a thin coat of lubricant to the back of your hand.

2.3 Replace lubricant

After the oil-lubricated bearings are drained of old oil, if possible, fill in fresh oil and let the machine rotate at a low speed for a few minutes. Can collect residual pollutants as much as possible, and then purge the oil, the oil is filtered before use.

Grease-lubricated bearings used when changing grease should avoid having cotton corners to any part of the bearing, because these residual energy can be wedged between the rolling parts and cause damage, especially small The application of bearings needs to pay more attention to this problem.

2.4 Covering exposed bearings

When inspecting bearings, never expose them to contaminants or moisture. If the work is interrupted, it should be oiled paper plastic sheet or similar.

If the exposed bearing is to be cleaned without disassembly and inspection may be performed, use a brush dipped in petroleum solvent to wash it, and then dry it with a lint-free cloth or blow dry it with compressed air (be careful not to let the bearing assembly starts to rotate). Use a small mirror and a probe similar to that used by a dentist to inspect the bearing raceways, retainers and beads. If the bearing is not damaged, perform relubrication as recommended by the manufacturer's lubrication instructions.

Do not clean sealed or dust-proof bearings; only wipe the outer surface. If the bearing is damaged, it needs to be replaced. It is far more economical to replace the bearings during the regular maintenance period than the loss of sudden shutdown due to damage to the array bearings.

3. Inspection and troubleshooting during operation

The inspection items during operation include the rolling sound, vibration, temperature, and lubrication status of the bearing, among which the rolling sound of the bearing and the vibration of the bearing are as mentioned above, and the lubrication is introduced here as follows:

3.1 The role of bearing lubrication

Lubrication has an important impact on the fatigue life, friction, wear, temperature rise, vibration, etc. of rolling bearings. Without normal lubrication, the bearing cannot be damaged. The reason for bearing damage shows that about 40% of bearing damage is related to poor lubrication. Therefore, good lubrication of the bearing is an effective measure to reduce the bearing size. In addition, the lubrication of bearings also has multiple functions such as heat dissipation, rust prevention, sealing, and shock mitigation. The functions of bearing lubrication are as follows:

a. A layer of oil film is formed between the two rolling surfaces or sliding surfaces that are in contact with each other to separate the two surfaces and reduce the friction and wear of the contact surfaces

b. When oil lubrication is used, especially when circulating oil lubrication, oil mist lubrication and oil spray lubrication are used, the lubricating oil can take away most of the inside of the bearing to effectively dissipate heat.

c. When using grease lubrication, it can prevent foreign matter such as external dust from entering the bearing and play a sealing role.

d. Lubricants have the effect of preventing metal corrosion.

e. Extend the fatigue life of the bearing.