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What factors must be considered in bearing selection?

wallpapers Industry 2020-07-29
Various types of bearings have different characteristics due to different designs. Due to the variability and complexity of the specific mounting position of the bearings and the application, the non-fixed mode of bearing type selection can be followed. When selecting the bearing type to adapt to the specific mounting position and application conditions of a certain host, it is recommended to integrate the following main factors. When considering the allowable space mechanical design, the size of the shaft is generally determined first, and then the bearing is selected according to the size of the shaft. Usually, small shafts use ball bearings; large shafts use cylindrical roller bearings, spherical roller bearings, tapered roller bearings (and sometimes ball bearings can also be used). If the radial space of the bearing installation part is restricted, a bearing with a smaller radial section height should be used. Such as needle roller bearings, some series of deep groove ball bearings, angular contact ball bearings, cylindrical roller or spherical roller bearings and thin-walled bearings. If the axial space of the bearing installation part is restricted, bearings with smaller width dimensions can be used.
Bearing load The size of the load is usually the decisive factor in selecting the size of the bearing. Roller bearings have greater carrying capacity than ball bearings with the same external dimensions. Usually ball bearings are suitable for light or medium loads, and roller bearings are suitable for heavy loads. For pure radial load, deep groove ball bearings and cylindrical roller bearings can be selected. For pure axial load, thrust ball bearings and thrust cylindrical roller bearings can be selected. When there is radial load and axial load (combined load), angular contact ball bearings or tapered roller bearings are generally used. If the radial load is large and the axial load is small, the bearing is professional on WeChat! Optional deep groove ball bearings and cylindrical roller bearings with ribs on the inner and outer rings. If there are large shaft or housing deformation and poor installation alignment, self-aligning ball bearings and spherical roller bearings can be selected. If the axial load is large and the radial load is small, thrust angular contact ball bearings can be selected. If the four-point contact ball bearing still requires alignment performance, thrust spherical roller bearings can be selected.
Speed ​​The working speed of rolling bearings mainly depends on their allowable operating temperature. Bearings with low friction resistance and less internal heating are suitable for high-speed operation. When only bearing radial load, deep groove ball bearings and cylindrical roller bearings can be used to achieve higher speeds. When bearing combined loads, angular contact ball bearings should be used. Specially designed high-precision angular contact ball bearings can reach extremely high speeds. The speed of various thrust bearings is lower than that of radial bearings. Rotational accuracy For most machinery, the use of 0-level tolerance bearings is sufficient to meet the requirements of the host, but when there are strict requirements on the rotation accuracy of the shaft, such as machine tool spindles, precision machinery and instruments, you should use deep groove balls with higher tolerance levels Bearings, angular contact ball bearings, tapered roller bearings, cylindrical roller bearings and thrust angular contact ball bearings.
The rigidity of a rigid rolling bearing is determined by the amount of elastic deformation that occurs when it is loaded. Generally, this amount of deformation is very small and can be ignored, but in some machinery, such as machine tool spindle systems, the static stiffness and dynamic of the bearing The stiffness has a great influence on the characteristics of the system. Bearing person WeChat professional! Generally speaking, roller bearings have higher stiffness than ball bearings. Various types of bearings can also improve their rigidity to varying degrees through proper "preloading". Noise and vibration The noise and vibration of the bearing itself are generally very low. But for small and medium motors, office machinery, household appliances and instruments that have special requirements for noise and smooth operation, low-noise bearings are usually used. The most common configuration method of axially moving bearings is to install a set of axially positioned "same bearings" on one end of the shaft, and install a set of axially movable "floating bearings" on the other end to prevent thermal expansion of the shaft. The phenomenon of freezing caused by cold shrinkage. The frequently used "floating bearing" is a cylindrical roller bearing with no ribs on the inner ring or outer ring. At this time, the inner ring and the shaft or the outer ring and the housing hole can be fitted with interference fit. Sometimes non-separable deep groove ball bearings or spherical roller bearings can be used as floating bearings, but when installing the inner ring and the shaft or outer ring and the housing hole, the clearance fit should be selected to ensure that the inner or outer ring has Enough freedom of axial movement.

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Tag: bearings