What is preload of crossed roller bearings? Generally, rolling bearings have a certain clearance under working conditions. However, in order to achieve a specific purpose, when the cross roller bearing is assembled, apply a certain internal load through adjustment of the clearance to achieve negative clearance. This method is called preload.
After the bearing is pre-loaded, the internal clearance is eliminated, and each rolling element is subjected to a certain preload, so that the cross roller ring is supported from all directions. Therefore the running accuracy is improved, and the shaft will be positioned correctly in the axial and radial directions.
The contact between the rolling element and the raceway is elastic contact. The rolling element can be regarded as a spring. Bearings with clearance are supported by only a few springs in the direction of force. But the pre-loaded cross roller bearings are spring-loaded in all directions and have a certain amount of preload. The number of rolling elements under load is greater than that when there is a clearance, so the stiffness can be improved.
After pre-load, the number of cylindrical rollers under load is increased, so the load on each roller is reduced. At the same time, the load can be evenly distributed on each rolling element, so the life of the bearing can be extended.
Pre-load makes a stable oil film between the rollers and the raceways of crossed roller bearings. This will improve the damping between the rolling elements and the raceways, and can improve the dynamic characteristics of the support structure and reduce noise.
The bearing will increase the clearance due to wear during operation. This situation can be compensated by pre-load of crossed roller bearings.