What factors must be considered when selecting bearings?

Allowable space:

Bearing load:

Load mode Deep groove ball bearings and cylindrical roller bearings can be selected for pure radial loads. Thrust ball bearings and thrust cylindrical roller bearings can be selected for pure axial loads. When there are both radial and axial loads (combined loads), angular contact ball bearings or tapered roller bearings are generally selected. If the radial load is large and the axial load is small, Bearing People WeChat Professional! Deep groove ball bearings can be selected and cylindrical roller bearings with flanges on both the inner and outer rings. If there are also large deformations of the shaft or housing and poor installation alignment, self-aligning ball bearings and self-aligning 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 also requires self-aligning performance, thrust self-aligning roller bearings can be selected.

Speed:

The operating speed of the rolling bearing mainly depends on its allowable operating temperature. Bearings with low friction resistance and less internal heat are suitable for high-speed operation. When only radial loads are applied, deep groove ball bearings and cylindrical roller bearings can be used to achieve higher speeds. If combined loads are applied, angular contact ball bearings should be selected. High-precision angular contact ball bearings with specially designed designs can achieve extremely high speeds. Various thrust The speed of the bearing is lower than that of the radial bearing.

Rotation accuracy:

For most machinery, the selection of 0-grade tolerance bearings is sufficient to meet the requirements of the main machine, but when there are strict requirements for the rotation accuracy of the shaft, such as machine tool spindles, precision machinery and instruments, deep groove ball bearings, angular contact ball bearings, tapered roller bearings, cylindrical roller bearings and thrust angular contact ball bearings with higher tolerance grades should be selected.

Rigidity:

The rigidity of rolling bearings is determined by the elastic deformation that occurs when they are under load. Under normal circumstances, this deformation is very small and can be ignored, but in some machinery, such as machine tool spindle systems, the static and dynamic stiffness of the bearings have a great influence on the characteristics of the system. Bearing people WeChat professional! Generally speaking, roller bearings have higher stiffness than ball bearings. Various types of bearings can also improve rigidity to varying degrees by appropriately "pre-tightening".

Noise and vibration:

The noise and vibration of the bearing itself are generally very low. However, for machinery with special requirements for noise and running stability, such as small and medium-sized motors, office machinery, household appliances and instruments, low-noise bearings are usually selected.

Axial movement:

The most common bearing configuration is to install a set of axially positioned "fixed bearings" at one end of the shaft and a set of axially movable "floating bearings" at the other end to prevent the shaft from getting stuck due to thermal expansion and contraction. The commonly used "floating bearings" are cylindrical roller bearings with no flanges on the inner ring or outer ring. At this time, the fit between the inner ring and the shaft or the fit between the outer ring and the housing hole can be interference fit. Sometimes inseparable deep groove ball bearings or spherical roller bearings can also be used as floating bearings, but when installing, the fit between the inner ring and the shaft or the outer ring and the housing hole should be a clearance fit to ensure that the inner ring or the outer ring has sufficient axial freedom of movement.

Friction torque:

The friction resistance of ball bearings is smaller than that of roller bearings. When pure radial load is applied, the friction resistance of radial contact bearings is small; when pure axial load is applied, the friction resistance of axial contact bearings is small; when combined load is applied, the friction resistance of angular contact bearings with a bearing contact angle close to the load angle is the smallest. In instruments and machinery that require low friction torque, it is more appropriate to use ball bearings or cylindrical roller bearings. Bearing people are professional on WeChat! In addition, low friction torque bearings should avoid contact seals. At the same time, it is recommended to use drip lubrication, oil-gas lubrication or other lubrication methods that are conducive to reducing wear.

Installation and disassembly:

Bearings with cylindrical inner holes are used in machinery that is frequently installed and disassembled. Separable angular contact ball bearings, tapered roller bearings, separable cylindrical roller bearings, needle roller bearings and thrust bearings should be preferred. Bearings with tapered inner holes can be installed on the shaft neck, or on the cylindrical shaft neck with the help of a tightening sleeve or a withdrawal sleeve, which is very convenient for installation and disassembly.