Bearing, believe everyone not unfamiliar, we often use the rolling bearing is supposed to be the most familiar with, it is the important parts of modern machinery and equipment.
What is air bearing?
What is the air bearing?
Air bearing (
气体轴承)
: with gas as smooth agent sliding bearing.
The most commonly used gas smooth agent for air, according to the demand is also available nitrogen, argon, hydrogen, helium and carbon dioxide.
In tight gas machine, shrinking machine and circulator, often working medium as smooth agent.
Air bearing refers to the use of sliding bearing of the pressure of the air membrane between vice appearance will load bearing, bearing up when work between sliding skin integrity by gas membrane separation.
Air bearing belongs to the sliding bearing, sliding bearing of the fluid at work as the fluid is smooth, smooth the medium of air.
Air bearing classification according to the mechanism of air film pressure, air bearing is divided into two main categories: air dynamic pressure bearing and aerostatic bearing.
Air dynamic pressure bearing the pressure of the air film is after sliding pair of each campaign will air into the region of convergence between the sliding pair appearance and composition, gas film roughly wedge-shaped.
Because the air dynamic pressure bearing external gas source don't demand, therefore, also known as 'the bearing'.
Aerostatic bearing pressure air is by external membrane squeeze air through the choke import between sliding pair of appearance.
Aerostatic bearing needs clean external gas source.
Figure 1 air dynamic pressure bearing principle figure 2 working principle of the aerostatic bearing characteristics of air bearing (1) very low friction due to gas was much lower than the liquid viscosity, viscosity of air at room temperature is only one over five thousand of the number 10 machine oil, and the bearing friction is proportional to the viscosity, so the gas bearing friction is lower than liquid smooth bearing.
(2) the applicable speed range of gas bearing friction is low, low temperature, the speed of up to 50000 RPM, are no more than 20 ~ 30 ℃, the temperature rise speed that up to 1. 3 million RPM.
Aerostatic bearing can also used for low speed, and zero speed.
(3) wide applicable temperature gas can in the temperature range of the gas, its viscosity is influenced by temperature is small (
Viscosity at higher temperatures also increases slightly, such as temperature from 20 ℃ to 100 ℃, and the air viscosity increased by 23%)
, consequently, the application of the gas bearing temperature range can be up to -
265 ℃ to 1650 ℃.
(4) load to the low dynamic pressure bearing load ability is proportional to the viscosity, the bearing capacity of gas dynamic pressure bearing ability as long as the same size of fluid dynamic pressure bearing a few parts per thousand.
As a result of the gas can be tight, the bearing capacity of gas dynamic pressure bearing to have a limit value, average unit load can only be added to the projection area 0.
36 million mpa.
(5) high processing precision request of gas bearing load to the gas film stiffness, usually adopt bearing clearance (smaller than liquid smooth bearing
Less than zero.
015 mm)
Accordingly, demand progress parts precision.
Air bearing applications of air bearing is used air elastic potential energy to a new type of bearing supporting role.
Only use the smooth agent is the air;
Therefore, about the necessary request of pollution-free artifacts, or work environment, air bearing technology is ideal.
In air bearing, ball bearing by air instead.
One of the most familiar application of air bearing is perhaps the hovercraft.
Big fan blowing air at the bottom of the hovercraft, through elastic rubber 'skirt' prevent air escaping.
Below the hovercraft produced by high pressure can support body weight, so make it floating on a cushion of air.
Since the 50 s, the application of gas bearing more and more common, and commonly and deepen the discussion.
The gas bearing can be used in textile machinery, cable machinery, instrument machine tools, gyroscope, high-speed centrifugal separation machine, the drill of hydrogen refrigerating machine, shrinking machine, low temperature operation and high temperature gas recycling device, etc.
