Bearing rigidity is important, 4 ways to teach you to increase bearing rigidity
The rigidity of a bearing is the amount of force required to produce a unit deformation of the bearing. The elastic deformation of rolling bearings is very small and can be ignored in most machines. However, in some machines, such as bearings or pinion bearings of machine tools, bearing rigidity is an important factor. Generally, cylindrical and tapered rollers should be used. Bearing.
The elastic deformation of rolling bearings is very small and can be ignored in most machines. However, in some machines, such as machine tool spindles, the rigidity of bearings is an important factor. Cylindrical roller bearings and tapered roller bearings are generally used. Because these two types of bearings are subjected to load, the rolling elements and the raceways are in line contact, and the elastic deformation is small and the rigidity is good. Ball bearings are point contact and have poor rigidity.
In addition, various types of bearings can also be pre-tensioned to achieve the purpose of increasing the rigidity of the support. For example, angular contact ball bearings and tapered roller bearings, in order to prevent the vibration of the shaft and increase the rigidity of the support, a certain axial force is often applied at the time of installation to press them against each other. Here specifically pointed out: the amount of preload should not be too large. When it is too large, the friction of the bearing will increase and the temperature rise will increase, which will affect the service life of the bearing.
1) The configuration of the bearing, the configuration of the bearing has a great influence on the rigidity of the bearing. Generally speaking, for the ball thrust bearing and the roller bearing of the centripetal thrust type, it is preferable to adopt a configuration in which the large end faces of the outer ring are opposed when used in pairs, so that the ability of the bearing to resist the overturning moment is large. The amount of pre-tension that is adjusted as the temperature changes is also less variable.
2) Multi-bearing support is adopted. Under the condition that the axial position allows, two or more bearings are used as radial support for each fulcrum, which can improve the support rigidity. For example, recently, in the spindle part of a machine tool, a plurality of sets of radial thrust bearings mounted axially preloaded as the shaft support of the same fulcrum are widely used.
3) For the matching surface of the bearing, the lower the surface roughness of the bearing mounting part on the shaft and the seat hole, the better the shape and positional accuracy, the higher the support rigidity is, and the surface strengthening treatment is applied to the above surface. It is beneficial to increase rigidity. The use of a high-hardness plug with a very low roughness, with a certain degree of interference in a lubricated state, multiple times to gently press in and exit the seat hole, is also beneficial to improve the support rigidity, if necessary, the collar can be similarly treated with a snap ring .
4) The bearing pre-tightening method is used to improve the bearing rigidity. The axial pre-tightening method can be adopted for the ball bearing or the tapered roller bearing, and the radial pre-tightening method can be adopted for the short cylindrical roller bearing, etc., which can significantly improve the rigidity of the shaft bearing. At this time, the bearing clearance is eliminated or a small negative clearance is obtained. However, under the condition that the rotation speed is not too high and the temperature rise is not large, it is better to adjust to a small negative clearance state.
The way to choose bearings from the concept of support rigidity is:
(1) Roller bearings are stiffer than ball bearings;
(2) Bearings with large dimensions are stiffer than bearings with smaller dimensions, even for bearings of the same diameter and larger width, which are stiffer than the smaller ones;
(3) Bearings with multiple number of rolling elements and many bearings with a large number of columns have good rigidity;
(4) Adjustable clearance bearing, which is beneficial to improve bearing rigidity i
(5) If necessary, use bearings without inner ring, without outer ring or without inner and outer rings, then reduce deformation and add roll number.
Reprinted from the network