Magnetic bearings are a new type of bearing. Specific data is currently not very detailed. Today, we tell you about the characteristics and classification of magnetic bearings. Magnetic bearings are supported by magnetic force load bearing or suspended form a rotor. Bearings developed rapidly in recent years, particularly in the high-speed, low friction, high (low) temperature and vacuum environment applications. Magnetic bearings compared with other forms of support has its unique advantages, promising.
1. Features ① low friction, low power consumption, ultra-high-speed operation. ② supporting high precision, stable and reliable. ③ at high temperature, cryogenic and vacuum environments running. ④ complex structure, requiring harsh conditions, magnetic interference on the environment, but no other contamination.
2. Classified according to their control magnetic bearings, magnetic energy source, structure and other classifications. In addition, you can also press the magnetic field of the permanent magnet type by type, type electromagnet and permanent magnets - the electromagnet mixed. Bearing suspension force can also be divided into a suction type type type and repulsion. Superconducting magnetic bearing is also divided into low and high temperature superconducting superconducting two kinds. All of the above categories between different types there are some special restrictions, should pay special attention. ① permanent magnet-type bearings only passive type (passive), while the passive type bearings impossible
3 both directions stable, at least in one direction should be active type. ② DC excitation type bearings can only be active type (active). ③ pure electromagnetic type bearings only five degrees of freedom control type bearings, volume, mass and power consumption are large. ④ repulsive type magnetic bearing, because the flux utilization is low, suction-type structure is more complex, it seldom used.
From the viewpoint of long-life, bearing selection requirements are:
(1) Select high load capacity of the bearing model
Bearing selection should take into account the price of the bearing, or use a higher load capacity but expensive bearings, or on the use of plain bearings while the other managed to extend its life.
Using a high load bearing capacity, for example, with a crown of cylindrical roller bearings with symmetrical rollers Spherical roller bearings, reinforced tapered roller bearings and ball bearings, ball groove ball bearings bus corrected, or 70000CD Bearings of series instead of groove (single radial) ball bearings, which have a high load capacity of the bearing or because of improved stress distribution, or because of a larger number of rolling bodies which may have a higher fatigue life.
(2) select the appropriate bearing size
For bearing size chosen, must be accurately calculated or actual work of checking the bearing load, speed and operating temperature.
Load the greatest influence on bearing life, so although the load but also the most difficult to measure as accurately measured. When the load measurements are in trouble, measure the actual motor power consumption, according to projections transmission line power loss and net along the way, until relatively close to the actual calculated bearing load. Calculated or measured load is too large, the fatigue life of the bearing can be expected with greater amplitude decreases inevitable, must try to remedy the situation. If the installation site allows optional one size larger files bearing; if the radial size is limited, there is a wide selection of bearings circumstances should be wider bearing; If you can not take advantage of a wider bearing load carrying capacity could be replaced higher bearings.
(3) Select the appropriate bearing material
Select bearing materials also take into account its price, but when you have to use a vacuum smelting or remelting steel, pay attention to perfect the lubrication conditions must, in order to exponentially increase the fatigue life of the bearing can be expected. Of course, the choice of this type of bearing quality steel than the cost of the system chosen higher load capacity of the bearing is much more expensive, but in the machine inaccessible and difficult to dismantle the bearing, or in mines, tunnels operating machinery used in bearings, overhaul extremely difficult situations, and sometimes must still be considered.



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