The high-speed precision spindle bearing must be pre-added with a certain axial load under normal working conditions. Its main purpose is to improve the rotation precision of the bearing, reduce the sliding of the rolling element at high speed, improve the rigidity of the bearing, and reduce the axial and radial directions of the bearing. The amount of turbulence increases bearing damping, reduces noise and increases bearing life.

The preload system of angular contact ball bearings is usually divided into three levels: light (A), medium (B), and heavy (C). The pre-tightening of the bearing is divided into two types: pre-tightening and constant-pressure pre-tightening.

Positioning the pre-tensioned bearing does not change the relative position of the components between the supports during use. When the angular contact ball bearing rotates at a high speed, due to the centrifugal force, the rolling element tends to "outer throw", so that the inner ring of the bearing tends to move axially relative, but since the position is relatively fixed, the result is inevitable The pre-tightening force of the bearing is increased, and the frictional heat is intensified. In addition, the change in operating temperature will also affect the size of the bearing housing and the size of the two bearing components, which in turn affects the pre-tightening state of the bearing. Therefore, when using the positioning pre-tightening method, attention should be paid to the influence of the change of the preload on the working performance of the bearing.

Constant pressure preloading is the use of elastic elements such as coil springs and butterfly springs to achieve proper preloading of the bearing at the support. Since the pre-tightening stiffness of the spring is generally much smaller than the rigidity of the bearing, the magnitude of the preloading load is determined by the pretensioning device itself, and the value is constant. In addition, the preload of the bearing support is not affected. The effect of temperature.

In short, the positioning pre-tension is beneficial to improve the rigidity of the bearing, and the constant pressure pre-tightening is suitable for the occasion of high-speed rotation.