Introduction to gas lubrication bearing strengths and weaknesses - bearing knowledge
So-called gas lubricated bearing means the use of gas lubricant lubrication for the interaction of the bearing, we common gas lubricant for air.
In is the use of gas lubricated bearing formation bearing mechanism and liquid gas film lubrication bearing the same.
When using gas lubricated bearing, therefore, have the following several major advantages and disadvantages.
Gas lubricated bearing 1, the advantages of high speed small helium turbine expander speed reached 650 000 r/min, the linear velocity of 238 m/s, calculated according to the dn value has reached 455 x106mm r/min.
2, high precision of gas film have error smoothing effect, its precision is higher than rolling bearing two orders of magnitude, and little vibration, low noise.
3, small gas viscosity friction loss is only one over one thousand of the lubricating oil viscosity, so the gas film internal friction caused by the friction torque is lower than that of the oil film three orders of magnitude.
4, suitable temperature range wide, atomic radiation can resistance to high temperature can reach 300 -
500 ℃, the temperature as low as 10 k gas bearing can still work.
5, pollution-free lubricating gas for air or inert gas, commonly released into the atmosphere does not produce pollution.
Bearing little vibration, low noise, also does not constitute a pollution to the environment.
6, long life aerostatic bearing has no direct contact with the metal, the theory of infinite life.
Consider other conditions, should be in commonly 104 h above.
Dynamic pressure gas bearing start-stop moment there is friction between the metal, affected by a certain life, but also in the more than 3000 h.
Gas lubricated bearing faults 1, low carrying capacity of gas lubrication bearing with the same kind of oil lubrication bearing ratio, low carrying capacity of about 1 ~ 2 orders of magnitude.
According to the bearing capacity per unit area, oil lubrication bearing is commonly (
5 ~ 2)
MPa, while gas lubricated bearing only (
2, poor reliability, on the one hand, gas lubricated bearing is easy to instability, a common hammer vibration and vortex instability phenomenon.
On the other hand is gas lubricated bearing binding, holding shaft or killed phenomenon also happen from time to tome.
3, need to manufacture high precision, high cost because of the gas film is thin, generally within a few microns to a few microns, and so on parts manufacturing precision demand is higher, increase the cost.
In addition, there are small holes and spiral groove, throttling porous materials and other special technical requirements, increase the manufacturing difficulty and cost.
4, working conditions are demanding gas lubricated bearing need high cleanliness of the work environment and strictly abide by the operation procedures, to ensure the normal work of the bearing, not an accident.
To this end, to a certain extent to limit its wide application and commercialization.