Introduction to roller bearings

Roller bearings are a type of rolling bearings and are one of the components widely used in modern machinery. It relies on rolling contact between major components to support rotating parts. Roller bearings are now mostly standardized. Roller bearings have the advantages of small starting torque, high rotation accuracy, and easy selection.

definition

Rolling bearings are divided into ball bearings and roller bearings according to the rolling force body.

Roller bearings rely on rolling contact between major parts to support rotating parts. Different roller bearings can withstand different radial and axial forces. When selecting roller bearings, the selection should be based on specific operating conditions.

Roller bearings mainly include spherical roller bearings, thrust spherical roller bearings, tapered rollers and cylindrical roller bearings and other structural types.

Type of choice

When selecting bearings, the main considerations are as follows:

Bearing load

The magnitude, direction and nature of the load on the bearing are the main factors in selecting the bearing.

When selecting bearings based on the size of the load, compared to the point contact of ball bearings, the main components in roller bearings are in line contact, which is easy to bear the load and the deformation after loading is also small.

When selecting bearings based on the load direction, thrust bearings are generally selected for pure axial loads. For larger axial forces, thrust roller bearings are selected. For smaller axial forces, thrust ball bearings are selected. For purely radial loads, deep groove ball bearings, cylindrical roller bearings or needle roller bearings are generally used. When bearing radial load as well as small axial load, you can choose deep groove ball bearings or tapered roller bearings; when the axial load is large, you can choose angular contact balls with larger contact angles. bearings or tapered roller bearings. 

Bearing speed

Under normal circumstances, the rotation speed will not have any impact on the selection of bearing type, but when the rotation speed is large, the rotation speed must be included in the bearing selection criteria.

(1) Compared with roller bearings, ball bearings have a higher limit speed, so in the case of high speeds, ball bearings are given priority.

(2) When the inner diameter is the same, the smaller the outer diameter, the smaller the rolling elements, so the centrifugal force exerted by the rolling elements on the outer ring is smaller, so it is more suitable to work at high speeds. According to the properties given in Table 1, needle roller bearings are more suitable for working at high speeds. 

Alignment performance of bearings

When the centerline of the shaft does not coincide with the centerline of the bearing seat and there is an angular error, or when the shaft is bent or tilted due to force, the axis of the inner and outer rings of the bearing will be deflected. At this time, self-aligning bearings or seated spherical ball bearings with certain self-aligning performance should be used.

Roller bearings are most sensitive to bearing deflection and may have a lower load-carrying capacity than ball bearings when deflected. Therefore, when the shaft stiffness and the support stiffness of the bearing seat hole are low, or when there is a large deflection moment, the use of this type of bearing should be avoided as much as possible. 

Bearing installation and removal

When the bearing seat has no split surface and parts must be installed and disassembled along the axial direction, priority should be given to bearings with separable inner and outer rings (such as N0000, NA0000, 30000, etc.).