Which factors must be considered in bearing selection?

"Various types of bearings have different characteristics due to their different designs.Due to the variability and complexity of the specific mounting position of the bearing and the application,the selection of the non-fixed mode of the bearing type can be adapted to the specific mounting position of a certain host When selecting bearing types based on application conditions,it is recommended to consider the following major factors.

Allowed space:

In mechanical design,the size of the shaft is generally determined first,and then the bearing is selected according to the size of the shaft.Generally,ball bearings are used for small shafts;cylindrical roller bearings,spherical roller bearings,and tapered roller bearings are used for large shafts(ball bearings may also be used sometimes).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:

Load size Load size is usually the decisive factor in selecting bearing size.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 person is WeChat professional!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 self-aligning performance,thrust spherical roller bearings can be selected.

Rotating speed:

The working speed of rolling bearing mainly depends on its 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.

Rotation 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,deep groove ball bearings with higher tolerance levels should be selected.Angular contact ball bearings,tapered roller bearings,cylindrical roller bearings and thrust angular contact ball bearings.

Rigidity:

The rigidity of a 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 and dynamic stiffness of the bearing 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.

Axial movement:

The most common way to configure bearings is to install a set of axially positioned"same bearings"at one end of the shaft,and install a set of axially movable"floating bearings"at the other end to prevent the shaft from expanding and contracting due to heat.A stuck phenomenon occurs.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 an 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 ring or outer ring has Enough freedom of axial movement.

Friction torque:

The friction resistance of ball bearings is lower than that of roller bearings.When pure radial load is applied,the friction resistance of radial contact bearing is small;when pure axial load is applied,the friction resistance of axial contact bearing is small;when combined load is applied,the bearing is in contact Angular contact bearings whose angles are close to the load angle have the least frictional resistance.In instruments and machinery that require low friction torque,ball bearings or cylindrical roller bearings are more appropriate.Bearing person WeChat professional!In addition,low friction torque bearings should avoid the use of contact seals.At the same time,it is recommended to use drip lubrication,oil-air lubrication or other lubrication methods that are conducive to reducing friction.

Installation and removal:

Bearings with cylindrical bores are used in machines that are frequently installed and disassembled.Separate angular contact ball bearings,tapered roller bearings,separable cylindrical roller bearings,needle roller bearings and thrust bearings should be preferred.The bearing with a conical inner hole can be installed on the journal,or on the cylindrical journal with the aid of an adapter sleeve or a withdrawal sleeve,which is very convenient for installation and disassembly.