The preloading method of the two crossed roller bearings achieves five effects

Preload is to give an axial force to the inner and outer rings of the bearing during assembly to eliminate the bearing clearance and cause initial deformation of the rolling elements in contact with the inner and outer rings. 

Preload can improve the stiffness and rotation accuracy of the crossed roller bearing under working conditions. 

So, what is the method of preloading crossed roller bearings? The following is a detailed summary for you

1. Two methods of preloading crossed roller bearings

Radial preload method:

The radial jacking method is generally used in tapered bore bearings bearing radial loads. A typical example is a double row precision short cylindrical roller bearing. 

The nut is used to adjust the axial position of this bearing relative to the tapered journal, so that the inner The ring has a suitable amount of expansion to obtain radial negative clearance, which is mostly used in machine tool spindles and jet engines.

Axial preload method:

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

① Positioning preload

In the positioning preload, the appropriate preload can be obtained by adjusting the size of the bushing or washer; the appropriate preload can also be adjusted by measuring or controlling the starting friction torque; 

The preload can also be directly adjusted by using the To achieve the purpose of preloading, there is generally no need for further adjustment at this time. In short, for any bearing that has been axially preloaded, its relative position will definitely not change during use.

② Constant pressure preload

The constant pressure preload is to use the coil spring, disc spring and other preload devices to make the bearing get proper preload. 

Since the stiffness of the spring is generally much smaller than that of the bearing, the relative position of the constant pressure preload bearing will change with the speed and external load during use. 

However, the size of the preload is determined by the preload device itself, so its value is basically unchanged, and it is not affected by the working temperature.

2. Five functions of cross roller bearing preload

① Improve the bearing rotation accuracy

After the cross roller bearing is preloaded, the internal clearance is eliminated, 

So that each rolling element bears a certain preload, and supports the ring from all directions, 

Which can improve the rotation accuracy and enable the bearing to perform axially and radially. 

Correct positioning, thereby improving the rotational accuracy of the bearing.

② Improve bearing stiffness

The contact between the rolling element and the raceway of the crossed roller bearing is elastic contact, and the rolling element can be regarded as a spring. Bearings with clearance are only supported by a few springs in the direction of force. 

The preloaded crossed roller bearing has spring support in all directions, and has a certain amount of preload, and the number of rolling under load is more than when there is clearance, so the rigidity can be improved.

③  Improve bearing life

After the cross-roller bearing is preloaded, the number of loaded rolling elements increases, the load on each bearing rolling element is reduced, 

and the load can be distributed evenly on each rolling element, so the cross-roller bearing can be effectively improved. bearing life.

④ Reduce bearing noise

Preload can establish a stable oil film between the bearing rolling element and the raceway, improve the damping between the bearing rolling element and the raceway, 

improve the dynamic characteristics of the support structure, and reduce the noise generated by the bearing operation.

⑤ Improve the dynamic performance of bearings

In the high-speed rotating crossed roller bearing, proper preload can prevent the gyroscopic rotation of the steel ball, prevent or reduce the revolving slip of the steel ball, and also control the spin sliding of the steel ball.

The commonly used preloading methods for crossed roller bearings are radial preloading method and axial preloading method of positioning preloading and constant pressure preloading. 

During the operation of the bearing, the clearance will increase due to wear, and these conditions can be effectively compensated and solved by preloading. 

The size of the preload load of the crossed roller bearing should be determined according to the load conditions and usage requirements.