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An article to let you know about high temperature bearings

Nov 17, 2022
What is the high temperature bearing?

High temperature bearing refers to a kind of high temperature resistant bearings, which can stably guarantee the excellent mechanical performance of the bearing in a high temperature environment for a long time. The working temperature of high temperature bearings is higher than that of ordinary bearings, and the general working temperature is above 150°.

High temperature bearing product category

High temperature bearing can be divided into two types in terms of structure and technology: the high temperature resistant ordinary structure type and the high temperature resistant special structure type.

High temperature resistant ordinary structure type

The ordinary structure high temperature bearing: Mainly refers to the bearings designed according to the common bearing structure, using high temperature resistant materials such as high temperature resistant bearing steel, etc., mainly including high temperature resistant self-aligning ball bearings, high temperature resistant deep groove balls and other bearings.

Spherical Ball Bearings
High-temperature spherical ball bearings: in the two raceways of the inner ring and the raceway for the spherical surface of the outer ring between, assembled by the keeper to guide the two rows of steel balls. Spherical ball bearings can withstand large radial load, but also can withstand a certain amount of axial load.
High temperature spherical ball bearings with stamped steel cages are lubricated with high quality white high temperature resistant grease and can be used in temperatures from -40 to +300°C. They can be used in operating conditions up to 300°C.
High temperature spherical ball bearings are usually produced to normal class tolerances and have a much higher clearance than normal bearings, so they are not usually suitable for high speed applications. However, they can usually be operated at speeds of up to 100 rpm for long periods of time.

Deep groove ball bearings
High temperature deep groove ball bearing: no internal keeper, only rolling body composition; can meet about 300 ℃ working conditions, according to the ordinary level tolerance production, and clearance is much larger than ordinary bearings, so usually not suitable for high-speed operation occasions, belong to the high temperature low speed bearing, usually can be in 200 rpm speed within the long-term operation.

High temperature resistant special structure type
Special structure high temperature resistant bearings: Not only are the materials used high temperature resistant materials, but also the structure to achieve automatic clearance compensation under high temperature environment, such as coil spring bearings, etc.

Features of high temperature bearings:

1. Lifetime lubrication, no grease is added during use.
2. Cost-effective, the quality is dozens of times higher than that of ordinary bearings.
3. It has won the trust of customers with its long service life.
4. High temperature bearings are widely used in machinery under high temperature operations such as metallurgy, kilns, glass, blast furnaces, and painting equipment.

High-temperature bearings are mainly used in aviation jet engines, gas turbines, nuclear reactor systems, X-ray tube tungsten discs and high-speed aircraft, rockets, spacecraft.

Installation of high temperature bearings

When installing the bearing, be sure to apply equal pressure around the circle of the end face of the ferrule. One side (such as the outer ring) exerts pressure, and the other side of the ferrule (such as the inner ring) is pressed in through the rolling element, which often causes indentations or scratches on the rolling element surface, which must not be used. Non-separable bearings are mounted on both the shaft and the bearing housing.

During the installation of the heater, it is necessary to know the temperature range of the high-temperature bearing under different high-temperature bearings.

Matching of high temperature bearings

1. Interference

The inner and outer rings of the rolling elements are fixed on the shaft or the bearing housing, and when they are under load, the relative movement between the ring and the shaft or the bearing housing does not occur in the radial, axial and rotational directions. This kind of relative movement will cause friction, frictional corrosion or frictional cracks on the mating surface, which will cause damage to the bearing, shaft and bearing housing, and then the friction powder will be mixed into the bearing, which will cause poor operation, abnormal heating or vibration. .
Regarding the way of fixing the bearing, it is best to leave an interference amount on the mating surface of the ring and the shaft or the bearing housing, and it is best to perform a static fit, which can make the load of the thin-walled ring evenly distributed on the circumference, Will not affect the load capacity of the bearing.

However, when the static fit is used, in addition to the inconvenience of installing and disassembling the bearing, if the bearing adopts a separate bearing, it cannot move axially, so it cannot be used in all occasions.

2. The choice of cooperation
The selection of cooperation is generally carried out according to the following principles:

(1) According to the direction and nature of the load acting on the bearing and which side of the inner and outer rings rotates, the load on each ring can be divided into rotating load, static load, or non-directional load. The ferrule should be a static fit (interference fit), and the ferrule that bears a static load can be a transition fit or a dynamic fit (clearance fit). When using a hollow shaft, a thin-walled bearing housing or a light alloy or plastic bearing housing, the interference must also be increased.
(2) When it is required to maintain high rotation accuracy, high-precision bearings must be used, and the dimensional accuracy of the shaft and bearing box should be improved to avoid excessive interference. If the interference is too large, the geometric shape accuracy of the bearing or axle box may be affected. The geometric shape of the bearing ring will damage the rotation accuracy of the bearing. If the inner and outer rings of a non-separable bearing (such as a deep groove ball bearing) use a static fit, it will be extremely inconvenient to install and disassemble the bearing. Cooperate.

3. Recommended cooperation
Regarding the shaft diameter and hole diameter tolerance of the shaft and bearing housing where the bearing is installed, in the metric series, ISO283 (dimensional tolerance and fit) has a corresponding standard. Therefore, the fit tolerance has been determined with the selected shaft diameter and hole diameter tolerance.
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