Matching of rolling mill bearings

Aug 16, 2021

Ⅰ Cooperate purpose

In order to obtain the best running performance of the bearing, the fit between the inner ring and the shaft and the outer ring and the housing hole must be appropriate. If the mating surface fits insufficiently, under load, the bearing ring will move relatively circularly on the shaft or in the bearing seat. This phenomenon will damage the shaft and the bearing seat, and cause abnormal heating or wear of the bearing. In order to prevent the relative circular motion of this kind of bearing, in addition to the axial positioning of the bearing, an interference fit design must be made for the rotating bearing ring and the mating surface, and the bearing ring that bears a static load generally does not require an interference fit. , Unless the bearing is subjected to vibration and shock load.

Ⅱ Coordination selection principle

In order to choose the most suitable fit, relevant factors such as load direction, load characteristics, load size, temperature conditions, installation and disassembly need to be considered.

1. Operating conditions

When the ferrule rotates or swings relative to the load direction, an interference fit should be selected;

when the ferrule is fixed relative to the load direction, a clearance fit can be selected; 

when the load direction is difficult to determine, an interference fit should be selected

2. Load condition

The greater the load, the greater the fit interference. When subjected to shock load or heavy load, a tighter fit than normal and light load should be selected.

3. Rotation accuracy

For occasions that require high rotation accuracy and smooth running, clearance fit should not be used. While improving the tolerance level of the bearing, the matching position of the bearing should also improve the accuracy

4. temperature

When the bearing is running, its temperature is usually higher than that of the adjacent parts, the fit between the inner ring and the shaft becomes loose, and the outer ring and the bearing seat are expanded to affect the axial movement of the bearing in the bearing seat. Therefore, the temperature difference between the bearing and the shaft and the bearing seat should be fully considered to select the corresponding fit

5. Installation and disassembly

Clearance fit is easy for bearing installation and disassembly. For applications that require interference fit and easy installation and disassembly, use separable bearings or tapered bore bearings

Ⅲ、Recommended fit for rolling mill bearings

When the inner ring is subjected to a rotating load, an interference fit is generally used; In order to facilitate installation, the inner ring and the journal of the four-row tapered roller bearing generally adopt a clearance fit, and are designed with lubricating oil grooves or oil lines on the end and inner diameter surfaces of the inner ring to reduce the wear of the inner ring and the roller. The outer ring is relatively static and generally adopts a clearance fit. For deep groove ball bearings or angular contact ball bearings that bear axial loads, while the inner ring adopts a clearance fit, sufficient clearance must be maintained between the outer ring and the box to avoid the bearing from bearing radial loads