Roller Bearing Installation Matters And Requirements

The fit and clearance of idler bearings Since idler bearings must meet the requirements of high-precision bearings and high-temperature bearings, when considering their fit and clearance, the following two points should be taken into account:

(1) Dimensional change and hardness change when rising from normal temperature to high temperature;

(2) Force system changes and shape changes caused by centrifugal force at high speed.

In short, under the condition of high speed and high temperature, it is difficult to maintain the precision and working performance of the bearing from the selection of fit and clearance.

In order to ensure that the raceway deformation of the idler bearing is small after installation, the interference of the interference fit cannot be too large, and the centrifugal force at high speed and thermal expansion at high temperature can offset the normal pressure of the mating surface. Or make the matching surface loose, so the interference must be carefully calculated under the premise of considering the above two factors. The effective interference at normal temperature and speed may be invalid for idler bearings.

If the calculation result is too contradictory (usually only at ultra-high speed), the only way to do this is to adopt double lubrication measures that combine the under-ring lubrication method and the static pressure lubrication method, and this solution may cause the dmn value of the bearing to break through 3 million mark.

Thermal expansion at elevated temperatures, or against the normal pressure of the mating surfaces. Or make the matching surface loose, so the interference must be carefully calculated under the premise of considering the above two factors. The effective interference at normal temperature and speed may be invalid for idler bearings.

If the calculation result is too contradictory (usually only at ultra-high speed), the only way to do this is to adopt double lubrication measures that combine the under-ring lubrication method and the static pressure lubrication method, and this solution may cause the dmn value of the bearing to break through 3 million mark.

When considering the clearance of idler roller bearings, not only the above factors must be considered, but also the influence of the thermal elongation of the shaft on the clearance should be considered. It is required that the bearing has the best clearance under the working condition, that is, at the working temperature, and This clearance is formed under the state of precise alignment of the ball groove centers of the inner and outer rings. Since the idler bearing strives to reduce relative sliding and internal friction, it is best not to adjust the clearance of the ball bearing by displacing the inner and outer rings in the axial direction.

When considering the fit interference and clearance of the bearing, it is necessary to pay attention to the characteristics that the material becomes soft and easy to deform at high temperature, and the possibility of permanent deformation caused by multiple temperature changes from normal temperature to high temperature.