In the application of machine tool bearings, the load capacity is not important when choosing the size of the bearing, but the rigidity, speed and accuracy are the decisive factors. However, when selecting the type of bearing, the magnitude and direction of the load should be considered. Generally speaking, the load capacity of a roller bearing is higher than that of a ball bearing under the same basic size.
1. Radial load
The double row cylindrical roller bearing in the sample has no ribs on the inner ring and can only bear radial loads, while angular contact ball bearings and tapered roller bearings can bear combined radial and axial loads.
2. Axial load
The bidirectional thrust angular contact ball bearings in the sample can bear axial loads in both directions. For the use of large bearings or heavier axial loads, it is recommended to use one-way thrust ball bearings or thrust cylindrical roller bearings.
3. Combined load
Combined load refers to simultaneous radial and axial loads. Angular contact ball bearings and tapered roller bearings mainly bear combined loads. The axial load carrying capacity of the bearing depends on the contact angle of the bearing. The larger the contact angle, the higher the axial load carrying capacity of the bearing.
4. Stiffness
The stiffness of the bearing is the characteristic of the amount of elastic deformation under the action of the load. Due to the different contact conditions between the rolling elements and the raceways, the stiffness of roller bearings is greater than that of ball bearings. Bearings can be preloaded to increase the stiffness of the spindle.
5. Bearing preload
The preload of the bearing can not only increase the rigidity of the bearing but also increase the precision of the bearing installation. Therefore, the bearings installed on the machine tool spindle are almost always preloaded.
a. Single row angular contact ball bearings and tapered roller bearings are installed back-to-back, and the preload (or clearance) is adjusted by the difference in the length of the inner and outer spacers between the two bearings. Tapered roller bearings are adjusted to zero or very small clearance.
b. Single row angular contact ball bearings can be combined into double bearings according to a certain preload.
c. The preload of cylindrical roller bearings with a tapered inner hole can be achieved by the interference of the inner ring and the tapered surface of the shaft.
d. The preload of the two-way thrust angular contact ball bearing can be adjusted by the length of the inner spacer.
e. High-speed angular contact ball bearings usually use springs to achieve axial preload.
