Advantages and Disadvantages of Gas Lubricating Bearing
2018-11-26 by zysbearing
The so-called gas lubricated bearing is the interactive bearing which uses the gas lubricant to carry on the lubrication, our common gas lubricant is the air. Is in use. The mechanism of gas lubricated bearing forming bearing film is the same as that of liquid lubricated bearing. Therefore, gas lubricated bearing has the following advantages and disadvantages.
Advantages of Gas lubricated bearings
1. High speed
The rotational speed of the small helium turbine expander has reached 650,000 rpm, the linear velocity is 238m / s, and by DN it has reached 455x106mm ·r / min.
2. High precision
The gas film has the effect of error homogenization, and its precision is two orders of magnitude higher than that of the rolling bearing, and the vibration is small and the noise is low.
3. Small friction loss
The gas viscosity is only 1/1000 of the lubricant viscosity, so the friction torque caused by internal friction of the film is three orders of magnitude lower than that of the oil film.
4. Wide applicable temperature range, can resist atomic radiation
High temperature up to 300-500 ℃, low temperature to 10 K gas bearing can still work.
5. No pollution
The lubricating gas is usually air or inert gas, which does not cause pollution to the atmosphere. The bearing vibration is small, the noise is low, and it does not pollute the environment.
6. Long life-span
The aerostatic bearing has no metal direct contact and the theoretical life is infinite. Considering other conditions, it should generally be above 104H. There is an intermetallic friction at the moment of starting and stopping of the dynamic pressure gas bearing, and the life is affected, but it is also above 3000h.
Shortcomings of gas lubricated bearings
1 . Low bearing capacity
The bearing capacity of the gas - lubricated bearing is about 1 - 2 orders of magnitude lower than that of the oil - lubricated bearing of the same kind . According to the bearing capacity of the unit area , the oil - lubricated bearing is generally ( 0.5 -2 ) MPa , and the gas - lubricated bearing is only ( 0.02 - 0.04 ) MPa .
2. Poor reliability
On the one hand, the gas lubricated bearing is easy to lose its stability, and the air hammer vibration and vortex instability are common, on the other hand, the gas lubricated bearing is stuck, and the phenomenon of holding the shaft or killing the shaft also occurs from time to time.
3. High manufacturing precision and high cost
Because the gas film is very thin, generally in the range of several microns to tens of microns, so the manufacturing accuracy of the parts is high, which increases the cost. In addition, there are special process requirements such as machining spiral grooves, throttle holes and porous materials. Increased manufacturing difficulty and cost.
4. Demanding working conditions
Gas lubricated bearings require a high cleanliness working environment and strict compliance with operating procedures to ensure that the bearings work properly and without accidents. Therefore, its wide application and commercialization are limited to a certain extent.
