Improvement of corrugated cage for four row cylindrical roller bearings

Abstract: In response to the problems of filling rollers in four row cylindrical roller bearings, the structure of the bearing was analyzed. The  corrugated  shaped cage was improved to reduce the outer diameter of the cage and the capacity of the rollers, which solved the problem.

Keywords: four row cylindrical roller bearing;  corrugated  shaped retaining frame; Lock quantity; Package capacity

1. Bearing structure

The structure of four row cylindrical roller bearings used in rolling mills is generally divided into three forms: FC, FCD, and FCDP. four row cylindrical roller bearings with an outer diameter of less than 500mm are mostly FC and FCD type FC type structures, as shown in Figure 1. The cage generally adopts a  corrugated  shaped brass solid cage as shown in Figure 2.

Figure 1 FC type four row cylindrical roller bearing

Figure 2 corrugated  cage before improvement

The inner ring of this type of bearing is interchangeable, and the outer ring, rollers, and cage form an outer component that can be separated from the inner ring. One side of the outer double edge is designed with a loading groove. In order to prevent the rollers from falling out of the loading groove during the operation of the bearing, the design depth has a certain locking amount for the rollers. The retaining frame is guided by the inner diameter of the outer ring edge, and the guide gap is generally 0.5-1mm, that is, the outer diameter of the retaining frame Dc=D2- (0.5-1) mm. Among them, D2 is the inner diameter of the outer ring edge.

2. Existing problems

During bearing assembly, a row of rollers needs to be loaded into the raceway from the outer ring filling groove, as shown in direction F in Figure 3. The locking amount (radial) of the cage on the roller is δ=Dw - Δ b. Where Dw is the roller diameter Δ b is the width at the outer diameter of the cage pocket hole. Due to the large capacity of the outer diameter of the cage for the rollers, the locking amount (radial) δ of the cage for the rollers is generally around 6mm; Therefore, the roller loading process is limited by these factors, making it difficult to load and often requiring the use of a copper hammer to strike it in. This also leads to the following problems during the loading process: (1) serious jamming on the outer raceway surface that cannot be eliminated internally due to jamming; (2) The roller end faces the inner wall of the cage pocket near the outer diameter surface, causing a momentary large cutting force, resulting in the presence of copper chips falling off inside the bearing, which affects the internal working environment of the bearing and seriously affects the rotational accuracy of the bearing, reducing its service life. Moreover, the labor intensity of workers during roller loading is relatively high, and the production efficiency is low.

Figure 3 Internal structural relationship diagram of bearings

3. Structural improvement

By analyzing the structure of four row cylindrical roller bearings, it can be concluded that the difficulty of roller installation depends on: (1) the size of the locking groove for the outer ring edge; (2) The size of the outer diameter of the cage relative to the capacity of the roller pack. To prevent the rollers from falling out of the loading groove during bearing operation, the locking amount of the outer ring edge on the rollers should generally not be reduced; So to reduce the difficulty of loading rollers, it can only be achieved by reducing the outer diameter of the cage to accommodate the rollers. The improved  corrugated  shaped holder is shown in Figure 4.

Figure 4 Improved corrugated cage

As shown in Figure 4, in order not to affect the guiding effect of the inner diameter of the outer ring edge on the retaining frame, the outer diameter dimension Dc at the guiding position of the retaining frame remains unchanged, and only the outer diameter dimension Dc1 at the pocket hole is reduced, and Dc is connected to Dc1 at a 30 ° angle to enhance the strength of the pocket hole root. Generally, Dcp-Dc1 is taken as 10-13mm (Dcp is the center diameter of the cage pocket). At this time, the outer diameter of the cage facing the roller's packing capacity is significantly reduced, and the locking amount of the cage to the roller is δ '=1-1.5mm. The minimum locking amount required by the design is 1mm to meet the requirements.

4. Conclusion

The improvement of the cage structure fundamentally solves the problems existing in the original structure, improves the rotational flexibility of the bearing, and extends the service life of the bearing. Tracking and verifying the assembly of the product shows that the difficulty of filling the rollers is significantly reduced, and the scratches on the raceway caused by the rollers are significantly improved, resulting in a decrease in labor intensity and an increase in production efficiency. Simultaneously improving and reducing its own quality has lowered manufacturing costs. ‚

2024 August 5th Week KYOCM Product Recommendation:

Corrugated ined Bearing：

Composite bearing is a kind of roller bearing which can bear both radial load and axial load. The structure of the  corrugated ined bearing is axial and radial bearing running at 900 °, the main load is borne by the radial bearing, and the axial bearing bears the lateral thrust.

Corrugated ination bearing is used together with profile guide rail or channel steel. There are two main types of profiles, I and C profiles. Thecorrugated ined bearing slides into the profile guide rail to generate the required linear movement. The corrugated ined bearing is welded with the flange plate for installation according to the application requirements. The assembly is mainly used for precise heavy vertical and horizontal movement.