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How to buy rolling bearings

Update:22 Feb 2020
Summary:

There are three kinds of loads that automobile rolling […]

There are three kinds of loads that automobile rolling bearing rings bear: partial load, cyclic load, and swing load. Normally, cyclic load (rotation load) and swing load adopt tight fit. Except for special requirements on application of some loads, tight fit is generally not suitable. When the rolling bearing ring bears a dynamic load and the load is heavy, the inner and outer rings should adopt an interference fit, but sometimes the outer ring can be loosened a little, and it should be able to move axially in the bearing housing housing hole. When the bearing ring bears the oscillating load and the load is light, a looser fit than a tight fit can be used.

Load size

Auto parts manufacturers The interference between their bearing ring and the shaft or housing hole depends on the load. When the load is heavier, use a larger interference amount; when the load is lighter, use a smaller interference amount. Cooperate. Ordinary radial load P is less than 0.07C is light load, P is greater than 0.07C and equal to or less than 0. 15C is normal load, P is greater than 0. 15C is heavy load (C is the rated dynamic load of the bearing).

Obligatory temperature

When the bearing is running, the temperature of the ferrule is often higher than the temperature of adjacent parts. Therefore, the inner ring of the bearing can loosen with the shaft due to thermal expansion, and the outer ring can affect the axial movement of the bearing in the housing hole due to thermal expansion. When choosing the fit, the temperature difference and expansion and contraction of the bearing device should be considered. When the temperature difference is large, the interference amount of the shaft and the inner ring should be greater.

Rotation accuracy

When automotive clutch bearings are required to have high rotational accuracy, in order to eliminate the effects of elastic deformation and vibration, clearance fits should be avoided.

Structure and material of bearing housing hole

In the case of a housing hole, an interference fit should not be used when mating with the bearing outer ring, and the outer ring should not be rotated in the housing hole. For bearings installed in thin-walled housing holes, light metal housing holes, or hollow shafts, tighter fits should be used than thick-walled housing holes, cast-iron housing holes, or solid shafts.

Easy installation and removal

For heavy machinery, bearings should be loose fit. When a tight fit is required, a differentiated bearing, a tapered bore on the inner ring, and an adapter sleeve or withdrawal sleeve bearing can be selected.

Axial displacement of the bearing

In the cooperation, when a bearing ring is required to move axially during operation, the bearing outer ring and the housing of the bearing housing should adopt a loose fit.

Choice of fit

The bearing and shaft are fitted with a base hole system, while the housing and the housing are fitted with a base shaft system. The fit between the bearing and the shaft is different from the tolerance matching system used in the machine manufacturing industry. The tolerance zone of the bearing inner diameter is mostly less than change. Therefore, under the condition of using the opposite fit, the fit between the bearing inner diameter and the shaft is usually closer . Although the tolerance zone of the outer diameter of the bearing and the tolerance zone of the base shaft are also below the zero line, their values ​​are not contrary to the ordinary tolerance system.