The concept and application of high temperature bearing and low temperature bearing
For bearings, the first and foremost thing is the quality to withstand high temperatures. There are many kinds of high temperature bearings, according to different needs and different environments, different types of bearings can be installed.
High temperature bearing can be divided into: ordinary structure high temperature bearing and special structure high temperature bearing. High-temperature bearings are widely used in high-temperature operation machinery such as metallurgy, furnaces, glass, blast furnaces, and painting equipment.
The models of high temperature resistant bearings and ordinary bearings are different, which can be divided into two situations:
1. The bearing parts are made of bearing steel and processed by high temperature tempering:
The code is in accordance with the regulations of JB/T2974 (the parts are subjected to high temperature tempering treatment, and the working temperature can reach 150C°, and the code is /S0; the parts are subjected to high temperature tempering treatment, and the working temperature can reach 200°C, and the code is set S1; the parts are subjected to high temperature tempering treatment, and the working temperature can reach 250°C, and its setting code is /S2; the parts are subjected to high temperature tempering treatment, and the working temperature can reach 300°C, and the setting code is /S3; High temperature tempering treatment, the working temperature can reach 350°C, and its code name is /S4).
2. Bearing parts are made of heat-resistant steel
The code is in accordance with JB/T2974 (the material is Cr4Mo4V, and the post code is /HN; the material is Cr14Mo4, and the code is /HN1; the material is Cr15Mo4V, and the code is /HN2; the material is W18Cr4V , Its suffix code is /HN3).
What material is the high temperature resistant bearing? Use heat-resistant bearing steel, also called high-temperature bearing steel. This steel has sufficiently high temperature hardness, high temperature wear resistance, high temperature affect fatigue strength, oxidation resistance and high temperature dimensional stability.
Currently used high-temperature bearing steel mainly includes the following three categories:
(1) Cr4Mo4V (M50) steel is a heat-resistant bearing steel with excellent performance, which has high hardness and fatigue life at high temperatures. It is mainly used in aero-engines and can be used at 315°C. The following long-term work can be used up to 430°C in a short time;
(2) Cr15Mo4 steel has high hardness and corrosion resistance in the range of 260-280°C, and can be used to manufacture corrosion-resistant bearings that work below 480°C, such as jet engines and Missile; (3) 12Cr2Ni3Mo5 (M315) is a widely used high-temperature carburized bearing steel, suitable for working below 430℃, and can be used to manufacture high-temperature bearings with complex shapes and impact resistance.
Bearings whose operating temperature is lower than -60°C are low temperature bearings. Mainly used in various liquid pumps, such as liquefied natural gas pumps, liquid nitrogen (hydrogen, oxygen) pumps, butane pumps, liquid pumps for rockets and missiles, space vehicles, etc.
Low-temperature bearings are not the bearings that run stably in high-temperature environments corresponding to high-temperature bearings, but refer to the design of special materials and structures to reduce the friction coefficient, thereby reducing friction and heating, so that the bearing can still maintain low temperature during long-term operation .
1. The world's leading bearing brands take bearing operating temperature as an important indicator
Therefore, the operating temperature of low-temperature bearings reflects the material technology and processing level of bearing processing. The measurement is mainly based on the temperature difference between the outer ring of the bearing and the injected cooling oil during operation.
Lower operating temperature means longer bearing life and higher performance. The world-renowned bearing manufacturers, relying on their respective advantages, are trying to obtain the comparative advantages of cryogenic bearings in many fields.
Take Timken spherical roller bearings as an example. After rigorous testing, the operating temperature of this company's products is lower than similar products in the market, about 15.5 degrees Celsius, while other internationally renowned brands are above 19 degrees Celsius.
2. The commonly used low temperature bearings are mostly single row deep groove ball bearings and cylindrical roller bearings are stuck in the bearing at low temperature. The external factor is the change of temperature, and the internal factor is the different thermal expansion coefficients of the shaft, frame and material. When the temperature range is large, the shrinkage rate of different materials is different, causing the gap to become smaller and jam. Therefore, for equipment with a wide range of work, including equipment used at low temperatures, it is necessary to calculate the expansion coefficient of the material, and at the same time try to use materials with similar expansion coefficients, the effect will be better. In addition, in the structural design, try to avoid using a tapered roller bearing at each end of the shaft. With this structure, the longer the distance between the two bearings, the greater the possibility of jamming. If one end of the shaft is equipped with a pa ir of tapered bearings, as the positioning of the shaft, the axial movement of the shaft is constrained. The other end of the shaft is used with the rolling bearing to limit the radial force only, and the axial temperature can follow the axial temperature.