Selection of solid inlaid self-lubricating bearings

               
Update: 26-05-2021
               
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In order to solve the lubrication problems of high temp […]

In order to solve the lubrication problems of high temperature, low speed, heavy load, heavy dust, water washing and shock and vibration in mechanical equipment, oil-free self-lubricating bearings are selected.

1. The structure of the bearing The self-lubricating bearing is a composite self-lubricating block made of a composite self-lubricating block embedded in a metal sleeve by developing well-arranged holes of appropriate size on the metal friction surface of the bearing matrix, and embedding molybdenum disulfide, graphite, etc. For bearings, the friction area of ​​solid lubricants reaches 25-65%. The solid self-lubricating block can work normally at a high temperature of 280℃. However, due to its low mechanical strength, weak load-bearing capacity, and easy deformation, it can be embedded in the metal hole and groove to suppress this shortcoming, forming the metal part to bear the load, and the self-lubricating block to lubricate.

The lubrication mechanism of this kind of self-lubricating bearing is that part of the self-lubricating material molecules are transferred to the metal surface of the shaft during the sliding friction process between the shaft and the sleeve, filling out the small unevenness, and forming a relatively stable solid lubricating film , Resulting in the friction between the solid lubricating film, to prevent the adhesive wear of the shaft and the sleeve. This reasonable combination combines the respective complementary advantages of copper alloys and non-metallic anti-friction materials, and is particularly suitable for motion amplitude in an oil-free, high temperature, high load, low speed, anti-fouling, anti-corrosion, and strong radiation environment, and It is used under special working conditions where it is soaked in water or other solutions and cannot be added lubricating grease at all.

2. The area occupied by the self-lubricating block is related to the operating speed and pressure-bearing strength. The operating speed is low; the pressure-bearing strength is large, and the area occupied by the metal should be larger. For example, the self-lubricating block of the walking wheel bearing of the spindle grabbing trolley occupies about 25% of the area, and the spindle bearing of the pulling mechanism must be sufficiently lubricated, and the pressure-bearing strength is not large. The self-lubricating block occupies about 65% of the area.

3. Technical requirements for bushing materials: self-lubricating bearing bushings should be made of alloy copper, and the bushings should have a higher hardness, generally requiring heat treatment, and their hardness should not be lower than HRC45.

4. The geometric shape and inlay requirements of the self-lubricating block. The shape of the self-lubricating block has two types: cylindrical and rectangular. The self-lubricating block can be cylindrical according to the size of the occupied area, otherwise it can be rectangular. Regardless of the shape, it must be inlaid firmly to prevent it from falling off during operation.

5. The matching clearance value between the bush and the shaft. The linear expansion coefficient of the self-lubricating block is about 10 times that of steel. In order to adapt to the change of bearing temperature, the gap between the shaft and the bushing is increased from 0.032~0.15MM to 0.45~0.5MM from the four-stage dynamic fit of the original metal parts (D4/DC4). The self-lubricating block protrudes from the bushing metal 0.2~0.4MM on the side of the friction pair. In this way, it will be fully lubricated during the initial running-in period of the bearing operation and reduce the consumption of power driving power.

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