What are the basic failure modes of tapered roller bearings

The basis for choosing fit.

According to the rotation of the load acting on the bearing relative to the ring, there are three kinds of loads on the bearing ring: local load, cyclic load and swing load. Usually, tight fit is used for cyclic load (rotating load) and swinging load, and tight fit is generally not suitable for local load except for special requirements. When the bearing ring bears the holding load and the load is heavy, both the inner and outer rings should adopt interference fit, but sometimes the outer ring can be slightly loosened and should be able to swim axially in the hole of the bearing housing shell; when the bearing ring bears the swinging load and the load is light, a fit which is slightly looser than the tight fit can be adopted.

Load size.

The amount of interference between the bearing ring and the shaft or shell hole depends on the size of the load. When the load is heavy, a larger amount of interference is used; when the load is lighter, a smaller amount of interference is used. Generally, when the radial load P is less than 0.07C, it is a light load, and P > 0.07C is equal to or less than 0. The normal load was at 15C, P > 0. Heavy load at 15C (C is the rated dynamic load of the bearing).

Operating temperature.

When the bearing is running, the temperature of the ring is often higher than that of the adjacent parts. therefore, the inner ring of the bearing may be loose with the shaft due to thermal expansion, and the outer ring may affect the axial movement of the bearing in the shell hole because of thermal expansion. When choosing the fit, the temperature difference, expansion and shrinkage of the bearing device should be taken into account. when the temperature difference is large, the interference between the shaft and the inner ring should be larger.

Rotation precision.

In order to eliminate the influence of elastic deformation and vibration, the clearance fit should be avoided when the bearing has higher rotation precision.

Structure and material of Hole in bearing Shell.

For the formal shell hole, the interference fit should not be used when matching with the bearing outer ring, and the outer ring should not be rotated in the shell hole. For bearings installed on thin-walled shell holes, light metal shell holes or hollow shafts, a tighter fit should be used than thick-walled shell holes, cast iron shell holes or solid shafts.

Convenient installation and disassembly.

For heavy machinery, loose fit should be used for bearings. When tight fit is needed, separate bearing, inner ring bearing with taper hole and tightening sleeve or unloading sleeve bearing can be selected.

Axial displacement of bearing.

In the fit, when a bearing ring is required to move axially in operation, the bearing outer ring and the housing housing hole should be loosely matched.

The choice of fit.

The matching of the bearing and the shaft is made of the base hole, while the matching of the bearing and the shell is made of the base shaft. The fit between the bearing and the shaft is different from the tolerance fit system used in the machine manufacturing industry, and the tolerance zone of the inner diameter of the bearing is mostly below the change. Therefore, under the condition of the same fit, the matching ratio of the bearing inner diameter and the shaft is usually more close. Although the tolerance zone of the outer diameter of the bearing and the tolerance zone of the base shaft are both below the zero line, their values are also different from the general tolerance system.