What is an oil-free bearing? How to lubricate oil-free bearings?

               
Update: 12-09-2020
               
Abst:

According to the different friction properties, the bea […]

According to the different friction properties, the bearing can be divided into sliding bearing and rolling bearing.
According to the different load direction, lubricant type, nature of lubricating film, structure of bearing bush and material of bearing bush, sliding bearing can be classified into oil lubricated bearing, grease lubricated bearing, water lubricated bearing, gas lubricated bearing, solid lubricated bearing, magnetic fluid bearing and electromagnetic bearing.
The so-called oil-free bearing generally refers to the sliding bearing, which belongs to the category of sliding bearing. If the oil-free bearing is defined from whether the lubricant has oil, water lubrication, air lubrication, electromagnetic, etc. can also be included in the oil-free bearing. Here, only the self-lubricating material or oil-bearing material, which is made by special process, and does not need to add lubricant in the working process, is introduced Shao. It mainly refers to inlaid solid lubrication bearing and self-lubricating bearing.
1 inlaid solid lubrication bearing
Taking JDB series inlaid solid lubrication bearing as an example, it takes metal materials as the matrix, and holes with proper size and orderly arrangement are opened on the matrix (brass, tin bronze, aluminum bronze, cast iron, GCr15 and other alloy materials), and then oil-bearing graphite, polytetrafluoroethylene (PTFE) and molybdenum disulfide particles are embedded as solid lubricating materials. When the bearing works under the condition of no oil lubrication, due to the effect of friction heat, the solid lubricating material will gradually transfer to the working surface of the friction pair, thus reducing the friction coefficient.
Widely used in: light industry, heavy industry, construction, metallurgy, transportation and other mechanical equipment, such as: continuous casting machine, rolling mill, injection molding machine, paper machine, mold guide pillar, ship, machine tool, etc.
Assembly method and process:
There are two kinds of assembly methods recommended for shaft sleeve, one is normal temperature pressing assembly method, the other is cooling assembly method. The cooling assembly method has the advantages of convenient operation and high matching accuracy, and it should be preferred when conditions are available. The method of seat hole heating should be avoided because the heat will damage the structure of bearing material.
Operation process:
① Put the bearing into the heat insulation container and put the cooling medium (liquid nitrogen or dry ice). The recommended cooling temperature is - 40 ~ - 70 ℃;
② The cooling time is more than 1 h. If the interference between the sleeve and the seat hole is large, the cooling time should be extended appropriately;
③ The outer diameter of the sleeve and the inner diameter of the seat hole are measured again to facilitate the smooth assembly;
④ If the cooling shaft sleeve is quickly installed into the seat hole, it will be difficult to install the shaft sleeve if the stopover time is too long;
⑤ Apply grease to the working surface of the shaft sleeve.
⑥ When the temperature is low in winter, the seat hole should be kept at 20 ~ 30 ℃.
2 self lubricating bearing:
It is made of self-lubricating material or oil-bearing material after special processing.

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