Pre tightening methods can be divided into two categories: radial pre tightening method and axial pre tightening method. A brief introduction is as follows:
The radial pre tightening method is commonly used in tapered hole bearings that bear radial loads. A typical example is a double row precision short cylindrical roller bearing, which uses nuts to adjust the axial position of this bearing relative to the tapered journal, so that the inner ring has appropriate expansion and obtains radial negative clearance. This method is often used in machine tool spindles and jet engines.
The axial preloading method can generally be divided into two types: positioning preloading and fixed pressure preloading.
In positioning pre tightening, the appropriate pre tightening amount can be obtained by adjusting the size of the lining or gasket; Suitable preload can also be adjusted by measuring or controlling the starting friction torque; Paired double bearings with pre adjusted preload can also be directly used to achieve the purpose of preloading. At this time, users generally do not need to make further adjustments. In short, any bearing that has undergone axial preloading will definitely not change its relative position during use.
Fixed pressure preloading is a method of using spiral springs, disc springs, etc. to achieve appropriate preloading of bearings. The rigidity of the pre tensioned spring is generally much smaller than that of the bearing, so the relative position of the fixed pressure pre tensioned bearing may change during use, but the pre tensioning amount remains roughly unchanged.
The comparison between positioning preloading and fixed pressure preloading is as follows:
(1) When the pre tightening amount is equal, the effect of positioning pre tightening on the increase of bearing rigidity is greater, and the impact of rigidity changes during positioning pre tightening on bearing load is also much smaller.
(2) During use, the axial length difference caused by the temperature difference between the shaft and bearing seat, the radial expansion caused by the temperature difference between the inner and outer rings, and the displacement caused by the load can cause changes in the preload amount; However, during use, the variation of preloading under constant pressure can be ignored.
Bearing torque, load, and service life
1. The torque required to initiate rotation of a bearing ring or washer relative to another fixed ring or washer.
2. Rotation torque The torque required to prevent the movement of another bearing ring or washer when one bearing ring or washer rotates.
3. The radial load acts on the load in the direction perpendicular to the axis of the bearing.
4. The axial load acts on the load in the direction of the parallel bearing axis.
5. Static load: The load acting on the bearing when the relative rotational speed of the bearing ring or washer is zero or when the rolling element has no movement in the rolling direction.
6. Dynamic load: The load acting on the bearing when the bearing ring or washer rotates relative to each other or when the rolling element moves in the rolling direction.
7. The general term used for calculating the theoretical load of equivalent load is that in specific situations, the bearing bears the actual load as if it were under the action of the theoretical load.
8. The radial basic rated static load corresponds to the total permanent deformation of the rolling element and raceway. If the rolling element and raceway are or are assumed to be normal busbars under zero load, the total permanent deformation generated at the contact between the rolling element and raceway under high contact stress is 0.0001 times the diameter of the rolling element. For single row angular contact bearings, the radial rated load is the radial component of the load that causes pure radial displacement of the bearing rings relative to each other.
9. The radial basic rated dynamic load is a constant radial load, under which the rolling bearing can theoretically withstand a basic rated life of 1 million revolutions. For single row angular contact bearings, the radial rated load is the component of the load that causes pure radial displacement of the bearing rings relative to each other.
10. The number of revolutions of one ring or washer relative to another ring or washer before the first occurrence of fatigue propagation in the material of a rolling element of a bearing, and the lifespan can also be expressed by the number of operating hours at a given constant speed.
11. The percentage of bearings that are expected to reach or exceed a specified lifespan for a group of nearly identical rolling bearings operating under the same conditions. The reliability of a set of bearings is the probability that the bearing will reach or exceed the specified lifespan.
12. The predicted lifespan is based on the radial basic rated dynamic load or axial basic rated dynamic load.
13. The rated life associated with basic rated life and 90% reliability.
14. Life coefficient is a correction factor applicable to equivalent dynamic load in order to obtain the basic rated radial dynamic load or basic rated axial dynamic load corresponding to the given rated life.
15. A component consisting of a radial bearing and a seat, with a base plate for installing screws on a supporting surface parallel to the bearing axis.
16. Vertical seat for rolling bearings.
17. The flange seat is a type of seat with radial flanges and screw holes for installation on the supporting surface perpendicular to the bearing axis.
18. A sleeve with a cylindrical inner hole and an axial opening, whose outer surface is conical and the small end has an external thread. Used to install bearings with tapered holes on shafts with cylindrical outer surfaces.
19. A sleeve with a cylindrical inner hole and axial opening, with a conical outer surface and an external thread at the large end. Used for installing or disassembling bearings with tapered holes on a cylindrical outer surface shaft.
The 20 locking nut is a screw nut with a cylindrical outer surface and an axial groove. The nut is locked with an outer claw of the locking washer and a circular wrench. Used for axial positioning of rolling bearings.
21. The locking washer is a thin steel plate washer with many external claws. One outer claw is used to lock the nut, and one inner claw is inserted into the axial groove of the locking sleeve or shaft.
22. One end of the eccentric sleeve has a groove steel ring with relative eccentricity of the inner hole, which is installed on the extended end of the equal eccentricity of the inner ring of the outer spherical bearing. Rotate the eccentric sleeve relative to the inner ring to tighten it, then tighten the top screw to secure it onto the shaft.
23. The steel ring installed on the wide inner ring of the outer spherical bearing with a concentric sleeve is threaded into the hole on the inner ring and in contact with the shaft.