Bearing lubrication is to enable the bearing to run normally, avoid direct contact between the raceway and the surface of the rolling body, reduce friction and wear inside the bearing, extend the service life of the bearing, as well as enhance the performance of the bearing.
At the same time, it can prevent rust and corrosion caused by the intrusion of foreign objects into the bearing.
This article introduces 11 kinds of lubrication methods commonly used in bearings, I hope it will help with your design.
1. Manual lubrication
This is the most primitive method. In the case of insufficient lubricant in the bearing, use an oiler to supply oil.
However, this method is difficult to maintain a certain amount of oil.
The risk of forgetting to refuel due to negligence is greater, and it is usually only used in occasions such as light load, low speed or intermittent exercise.
When it is best to operate, set a dust cover or ball valve on the fuel hole, and use felt, cotton, wool, etc. as a filtering device.
2. Drip point lubrication
It is usually used for light and medium load bearings with a peripheral speed of less than 4 to 5 m / s.
Approximately constant quantity of lubricating oil is supplied from the container through holes, needles, valves, etc.
The most classic is the drip oil cup.
The amount of oil dripping varies significantly with the viscosity of the lubricant, bearing clearance and the position of the oil supply hole.
3. Oil ring lubrication
The ring that hangs on the shaft and can rotate brings the oil from the oil pool into the bearing (only for the lubrication method of the horizontal shaft).
It’s suitable for medium and high speed bearings with shaft diameters greater than 50mm. The oil ring is best to be seamless.
When the bearing aspect ratio is less than 2, you can only use one oil ring, otherwise two oil rings are required.
4. Oil rope lubrication
Relying on the capillary and siphon action of the oil rope, the lubricating oil in the oil cup is introduced into the bearing, which is mainly used for light and medium load bearings with a peripheral speed of less than 4-5 m / s.
In addition, the oil rope can play a filtering role in the whole process.
5. Oil pad lubrication
Use the capillary action of the oil pad to apply the lubricating oil in the oil pool to the surface of the shaft diameter.
This method can always keep the friction surface clean, but dust can also block the pores and cause insufficient oil supply.
The oil supply amount of oil pad lubrication is usually only 1/20 of oil lubrication.
6. Oil bath lubrication
This lubrication method is to immerse a part of the bearing in lubricating oil.
It is often used for thrust bearings of vertical shafts, and is not suitable for radial bearings of horizontal shafts.
7. Splash lubrication
The lubricating oil splashed by the flapping of the rotating parts in the oil tank is supplied to the bearing, which is suitable for higher speed bearings.
8. Spray lubrication
The lubrication method of atomizing the lubricant and spraying it on the friction surface, which is suitable for high-speed bearings.
9. Pressure oil lubrication
Oil is supplied to the bearing by the pressure of the lubrication pump, and the lubricating oil flowing from the bearing is recovered to the oil pool for recycling.
It is the most stable and most lubricating method for oil supply.
It is suitable for high speed, heavy load and important sliding bearings.
10. Circulating oil lubrication
The filtered oil is delivered to the bearing parts with an oil pump, and the lubricating oil after passing through the bearing is filtered and cooled before being used.
Since the circulating oil can take away a certain amount of heat and cool the bearing, this method is suitable for bearing components with high speed.
11. Jet lubrication
Use the oil pump to shoot the high-pressure oil into the bearing through the nozzle, and the oil injected into the bearing flows into the oil groove through the other end of the bearing.
When the bearing rotates at a high speed, the rolling elements and the cage also cause the surrounding air to form an airflow at a relatively high rotation speed, and it is difficult to send lubricating oil into the bearing by the general lubrication method.
At this time, the lubricant must be sprayed into the bearing by high-pressure spraying.
The position of the nozzle should be placed between the inner ring and the center of the cage.
6 selection principles of lubrication methods
After the above analysis, the advantages and disadvantages of various lubrication methods have been comprehensively evaluated.
Therefore, in terms of bearing lubrication method selection, the appropriate method can be selected according to the actual operating conditions.
The main principles can be summarized as follows point:
1) If the running speed of the bearing and the temperature rise index are reasonable, then the method of grease can be selected first.
2) Of all the methods of lubricating oil, drip oil lubrication is the higher comprehensive index in terms of technology and economy, so attention should be paid to the selection process.
As far as drip oil lubrication is concerned, if it can be said that the automation system can be applied to it and the drip oil lubrication can be controlled better, then this method will have a good development prospect.
3) If it is a heavy-duty bearing with a low speed or a hollow bearing with a high speed, you can choose the lubrication method of pressure cycle.
4) High-speed light-load bearings can be selected with dispersed droplets or oil mist lubrication; high-speed heavy loads should be spray-lubricated.
5) The comprehensive technical and economic indicators of splash lubrication and oil bath lubrication are low, and should be used as little as possible or not to use.
6) If it is a bearing in a complete set of equipment, in the process of selecting the lubrication method, the lubrication methods and characteristics of other components should be fully considered, and the lubricant of the same model or the same variety should be used as much as possible, so that during operation, it can reduce a lot of running costs.
Bearing lubrication is a continuous task, and the replacement cycle of the lubricant is based on the conditions of use of the bearing and the amount of oil.
Generally, it should be replaced once a year when it is used in a good environment where the operating temperature is below 50 ° C and there is little dust.
When the oil temperature reaches 100 ° C, it should be replaced every 3 months or less.