Determination of bearing clearance

The internal clearance of the bearing is the total distance that one of the bearing rings can move in a radial (radial clearance) or axial (axial clearance) relative to the other bearing ring. The clearance of the bearing before installation is the initial clearance. The clearance of the imported bearing when it reaches the working temperature after installation is the working clearance. The interference fit of the bearing on the shaft or in the bearing housing can cause the bearing ring to elastically deform (expand or compress), resulting in a reduction in the internal clearance of the bearing. However, a certain minimum clearance must be maintained to avoid damage to the bearing.

For tapered roller bearings, the axial clearance is mainly considered. The slanting of the slewing gears of the high-speed shaft of the slewing gearbox is adjusted by the spring preloading method, and the bearing clearance is 0. 3mm. The axial clearance of the bearing is 0. 18~0. 23mm, and the axial clearance of the bearing is not guaranteed. Obviously, the original design drawing gasket thickness is not suitable, resulting in excessive bearing preload and a sharp decrease in service life. The proper preload at normal operating temperatures depends on the bearing load. Tapered roller bearings can withstand both radial and axial loads. Under radial load, a force acting in the axial direction is generated in the bearing, which is generally carried by the second bearing, which faces in the opposite direction to the first bearing. The pure radial displacement of one bearing ring relative to the other bearing ring means that half of the circumference of the bearing (ie half of the rolling element) is subjected to a load, and the axial force generated in the bearing is: Fa=0.5Fr/Y (7) Medium Fr—the radial dynamic load of the bearing, that is, half of the radial force of the gear shaft, is Fr=0.5Fr2=0.5×5 193=2 596. 5N; Y———The calculation coefficient of single row tapered roller bearing Take 1.4. The pre-tightening force of the mating bearing should be greater than Fa.

    Using Bearing Knowledge In a bearing configuration consisting of two tapered roller bearings facing each other, each bearing must withstand axial forces from another bearing. When the two bearings are the same, the radial load acts on the center of the two bearings. If the bearing arrangement is adjusted to zero clearance, half of the rolling parts can automatically reach the load distribution when subjected to load. Under other load conditions, especially when there is an external axial load, it may be necessary to preload the bearing to compensate for the axial load. Due to the play caused by the elastic deformation of the bearing, a more favorable load distribution can be achieved on another bearing without axial load. According to the relationship between bearing preload and axial displacement, if the external axial force exceeds the value of F0, the bearing B will release the axial preload force, and the axial displacement under the additional load will be the same as that of the non-preload bearing. It is completely determined by the spring constant of the bearing A. The actual test shows that the bearing stiffness and life requirements can be well satisfied.