A customer asked how to preload rolling bearings two days ago, so today I will introduce to you what are the methods for preloading rolling bearings?

Rolling bearing preloading methods are divided into two categories: radial preloading method and axial preloading method:

1. Radial preloading method

The radial preloading method is mostly used in tapered bore bearings that bear radial loads. A typical example is a double row precision short cylindrical roller bearing. The nut is used to adjust the axial position of the bearing relative to the tapered journal, so that the inner ring has a proper expansion to obtain a negative radial clearance. This method is mostly used in machine tool spindles and jet engines.

The axial preloading method can be roughly divided into two types: positioning preload and constant pressure preload.

In the 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 directly use the pre-adjusted preload To achieve the purpose of preloading, the user generally does not need to adjust it again. In short, the relative position of any bearing that has been axially preloaded will definitely not change during use.

Constant pressure preloading is a method that uses coil springs, disc springs, etc. to properly preload the bearings. The rigidity of the pre-tensioned spring is generally much smaller than that of the bearing, so the relative position of the fixed-pressure pre-tightened bearing will change during use, but the preload is roughly the same.

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

(1) When the amount of preload is equal, the positioning preload has a greater effect on the rigidity of the bearing, and the effect of rigidity changes on the bearing load during 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 will cause the pre-tightening The amount changes; while the constant pressure preload is in use, the change of the preload is negligible.