Selection of oil-free self-lubricating bearings

In order to solve the lubrication problems of high temperature, low speed, heavy load, dust, water flushing and impact vibration in mechanical equipment, oil-free self-lubricating bearing is selected.
1. The structure of the bearing self-lubricating bearing is to develop holes with proper size and orderly arrangement on the metal friction surface of the bearing matrix, and embed molybdenum disulfide, graphite, etc. to make a composite self-lubricating sliding block, which is embedded in the metal sleeve. The friction area of the solid lubricant is 25-65%. The solid self lubrication slide can work normally at 280 ℃. However, due to its low mechanical strength and weak bearing capacity, it is easy to deform. If it is inlaid in the metal hole and groove, this defect can be restrained. The metal part plays the role of bearing and the self lubricating sliding block plays the role of lubrication.
The lubrication mechanism of the self-lubricating bearing is that in the sliding friction process between the shaft and the sleeve, a part of the self-lubricating material molecules transfer to the metal surface of the shaft, fill up the micro non-plane, and form a relatively stable solid lubrication film, resulting in the friction between the solid lubricating films and preventing the adhesion wear between the shaft and the sleeve. This reasonable combination combines the complementary advantages of copper alloy and non-metallic antifriction materials. It is especially suitable for oil-free, high-temperature, high-load, low-speed, anti-fouling, anti-corrosion and strong radiation environment, as well as the special working conditions in which lubricating grease cannot be added due to water or other solutions.

2. The area ratio of self lubrication slide block to surface area of self lubrication slide block is related to the running speed and bearing strength, and the running speed is low; if the bearing strength is large, the metal area should be larger. For example, the area of the self lubricated slide block of the walking wheel bearing of the ingot trolley is about 25%, and the bearing of the spindle pulling mechanism should be fully lubricated, and the bearing strength is not large. The area of the self lubricating sliding block is about 65%.
3. According to the technical requirements of bushing material, the bushing shall be made of alloy copper, and the bushing shall have high hardness, and generally it shall be heat treated, and its hardness shall not be lower than hrc45.
4. The geometric shape and inlay requirements of self lubricating slide block. There are two types of self lubrication slide block: cylindrical and rectangular. According to the size of self lubrication area, column shape can be used, otherwise rectangle can be used. No matter what shape, it must be inlaid firmly to prevent falling off during operation.
5. The linear expansion coefficient of the self lubricated slider is about 10 times that of the steel. In order to adapt to the change of bearing temperature, the clearance between shaft and bushing is increased from 0.032 ~ 0.15mm to 0.45 ~ 0.5mm from the original four stage dynamic fit of metal parts (D4 / DC4). The self lubricating sliding block protrudes 0.2 ~ 0.4mm from the lining metal on one side of the friction pair. In this way, the bearing will be fully lubricated during the initial running in period, and the consumption of power driving power will be reduced.

6. Advantages of oil-free self-lubricating bearing
A. No oil lubrication or less oil lubrication, suitable for the places where it is impossible or difficult to add oil. It can be used without maintenance or less maintenance;
B. Good wear resistance, low friction coefficient and long service life;
C. With a proper amount of elastic-plastic, the stress can be distributed on a wide contact surface and the bearing capacity can be improved;
D. The static and dynamic friction coefficient is similar, which can eliminate the crawling at low speed, so as to ensure the working accuracy of the machine;
E. It can reduce vibration, noise, pollution and improve working conditions;
F. In the process of operation, the transfer film can be formed to protect the grinding shaft without shaft biting;
G. The hardness requirement of grinding shaft is low, and the shaft without conditioning can be used, which reduces the machining difficulty of related parts;
H. Thin wall structure, light weight, can reduce the mechanical volume;
1. The bushing is made of brass and can be used in corrosive medium.
Through the practice of an aluminum enterprise, the casting machine bearing has been changed into oil-free self-lubricating bearing, which has been used for 15 months continuously and is still in operation. The clearance between shaft and bushing is generally less than 1 mm. It is estimated that it can be used for another 12 months, significantly exceeding the original service life (2 months).
The oil-free self-lubricating bearing can not only be well used in aluminum ingot casting machine, but also adapt to the motion range in the environment of no oil, high temperature, high load, low speed, anti fouling, anti-corrosion and strong radiation environment, as well as the equipment under special working conditions in which lubricating grease cannot be added due to water or other solutions. This kind of bearing has a wide application value.
At present, most of the bearings used in various mechanical industries are ball bearings, needle rollers, etc., but a small part of them have adopted self-lubricating bearings. I believe that in the near future, self-lubricating bearings will become the dominant bearings. The following are the application features and advantages of some self-lubricating bearings:
1. No oil lubrication or less oil lubrication, suitable for the places where it is impossible or difficult to add oil. It can be used without maintenance or less maintenance;
2. Good wear resistance, low friction coefficient and long service life;
3. With a proper amount of elastic-plastic, the stress can be distributed on a wide contact surface and the bearing capacity can be improved;
4. The static and dynamic friction coefficient is similar, which can eliminate the crawling at low speed, so as to ensure the working accuracy of the machine;
5. It can reduce vibration, noise, pollution and improve working conditions;
6. In the process of operation, the transfer film can be formed to protect the grinding shaft without shaft biting;
7. The hardness requirement of grinding shaft is low, and the shaft without quenching and tempering treatment can be used, which reduces the machining difficulty of related parts;
8. Thin wall structure, light weight, can reduce the mechanical volume;
9. At present, it has been widely used in the sliding parts of various machinery, such as printing machine, textile machine, tobacco machinery, micro motor, automobile, motorcycle, agricultural and forestry machinery, etc.