Radial preloading method and axial preloading method of rolling bearing

Preloading methods are divided into two categories: radial preloading method and axial preloading method, which are briefly introduced as follows:

1. Radial preloading method

The radial jacking method is mostly used in the tapered bore bearing that bears radial load. A typical example is the double row precision short cylindrical roller bearing. The axial position of this bearing relative to the tapered journal is adjusted by the nut to make the inner The ring has a proper amount of expansion to obtain a negative radial clearance. This method is mostly used in machine tool spindles and jet engines.

2. Axial preload method

The axial pre-tightening method can be roughly divided into two types: positioning pre-tightening and constant pressure pre-tightening.

In positioning preload, you can adjust the size of the bush or gasket to obtain the proper preload; you can also measure or control the starting friction torque to adjust the proper preload; you can also use the pre-adjusted preload directly To achieve the purpose of pre-tightening, the user generally does not need to adjust again at this time. In short, the relative position of any bearing that has been axially pre-tightened will definitely not change during use.

Constant pressure preloading is a method of using coil springs, disc springs, etc. to properly preload the bearings. The rigidity of the preload spring is generally much smaller than the rigidity of the bearing, so the relative position of the bearing preloaded under constant pressure will change in use, but the preload is roughly the same.

The comparison between positioning preload and constant pressure preload is as follows:

(1) When the preload is equal, the positioning preload has a greater effect on the rigidity of the bearing, and the effect of the rigidity change on the bearing load during the positioning preload is also much smaller.

(2) Positioning pre-tightening in use, due to the axial length difference caused by the temperature difference between the shaft and the bearing seat, the radial expansion caused by the temperature difference between the inner and outer rings, and the displacement caused by the load, etc., will cause the pre-tightening The amount changes; while the constant pressure preload is in use, the change of the preload is negligible.