2022 December the Fifth Week VISTA Technical Knowledge: On the Optimization Direction of Extra Large Cylindrical Bearing


Bearing structure, performance characteristics, damages and differences of oversized cylindrical bearings and optimization direction.

 

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With the popularization of the six high cold rolling mill and the improvement of AGC, the rolling mill has been developing towards high load and high speed. The linear speed can reach 800-1000m/min. When the rolling mill is running, the backup roll bears all the radial loads during rolling. The bearing is required to provide the maximum radial load and rigid support in the effective radial and axial space, which requires that the bearing must be designed with high load, high rigidity and high precision, At present, FCDP four row cylindrical roller bearing is the preferred structure because its structure and characteristics meet the requirements of the main bearing of the backup roll system of the rolling mill.

 

Bearing structure

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As a typical rolling mill roll bearing, FCDP cylindrical roller bearing can provide the maximum radial bearing capacity and lower friction coefficient compared with other types of bearings in a given installation space. The bearing consists of two movable retaining rings, one movable spacer ring, two outer rings, four row roller assemblies and two inner rings.

 

Performance characteristics

High precision

The structure has a high degree of separation. The retaining ring and spacer ring are movable detachable rings. The outer ring is close to a regular ring piece. The inner ring is a standard ring piece, and the overall part is a regular geometry, which is more convenient for precision control of the workpiece during machining.

 

Bearing strength

The rolling element is designed as a hollow structure. The cage strut passes through the rolling element center, saving the circumferential arrangement space of the whole set of bearing rolling elements. Compared with the bearings of the same size series, the bearing can accommodate more rolling elements, greatly improving the bearing capacity.

 

Local interchange

The bearing outer ring component and inner ring can be separated. After installation, the outer component is installed in the bearing box, and the inner ring interference is installed in the roll journal. In the process of use, the inner ring and outer ring components can be interchangeable.

 

Easy to check

After disassembly, the interference of the inner ring is installed on the roll journal following the roll journal, and the outer ring assembly is integrated with the bearing box, which can visually detect the use of key parts such as the bearing inner ring, the rolling element, and the outer ring load area.

 

Easy to clean

The bearing has a high degree of separation, and the inner ring, outer ring, spacer ring and roller components can be separated. The grease and foreign matters adsorbed on the surface of the parts can be efficiently and quickly cleaned during machine washing or manual cleaning.

 

According to the summary of market research, there are mainly the following types of damages and differences of oversized cylindrical bearings

1. After a certain period of use, the outer ring has a large deformation, with an average elliptical value of 0.15 mm, which makes it difficult to install the second or third time, and serious problems directly lead to the inability to install;

2. The design length, quantity and diameter of rolling elements differ greatly. The average diameter difference of rolling elements of the same type of bearing reaches 3mm, the average length difference reaches 8mm, and the average number difference reaches 10;

3. The rolling body and the rib are grinded, and the problem of rolling body and rib grinding burrs occurs in the middle of use;

 

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4. Serious installation or removal scratches and gouges on the surface of rolling element and inner ring;

 

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5. Some rolling elements are damaged by fatigue in advance or the bearing area of the outer ring single row raceway is peeled off;

 

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6. The cage is damaged and desoldered, and the prop is broken;

 

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Optimization direction

1. According to the fact that the outer ring is easy to deform and has large radial load, it is necessary to adjust the wall thickness of the outer ring. Properly adjust the section ratio of the rolling element to the outer ring, and thicken the outer ring. First, ensure that the bearing has sufficient rigidity, ensure that the elastic deformation of the bearing is infinitely reduced during operation, ensure the uniform distribution of load, and improve the overall operating life of the bearing;

2. By adjusting the spacing between the rolling elements, the spacing L between adjacent rolling elements can be compressed to save space and increase the number of rolling elements;

3. According to the objective problem of sliding friction between the rib and the end face of the rolling element, strictly control the parallelism between the rib and the end face, strictly control the warping deformation of the edge retainer ring, and strictly control the roughness value of the rib contact end face;

4. The cage belongs to pure passive motion and runs through the rolling element at the same time. It is necessary to accurately configure the clearance h between the cage strut and the rolling element hole, which is easy to lubricate and impact resistant. At the same time, it is necessary to strictly control the deformation of cage components after connection (thread and welding) to keep the minimum, so as to prevent the rolling element from running track deflection;

5. According to the periodic disassembly of the bearing, the disassembly tools can be optimized or modified according to the structure of the bearing box and the on-site conditions of the disassembly, so as to eliminate the collision damage to the bearing during the disassembly process to the maximum extent.

 

More about VISTA Cylindrical Roller Bearing:

As a Cylindrical Roller Bearing manufacturer, Vista supplies the following series Cylindrical Roller Bearing for the customers: single row Cylindrical Roller Bearing, double row Cylindrical Roller Bearing, three row Cylindrical Roller Bearing, four row Cylindrical Roller Bearing.

 

Cylindrical roller bearings are available in a wide range of designs, series, variants and sizes. The main design differences are the number of roller rows and the inner/outer ring flanges as well as cage designs and materials.

 

Cylindrical roller bearings are also available in sealed or split designs. In sealed bearings, the rollers are protected from contaminants, water and dust, while providing lubricant retention and contaminant exclusion. This provides lower friction and longer service life. Split bearings are intended primarily for bearing arrangements which are difficult to access, such as crank shafts, where they simplify maintenance and replacements.

 

Cylindrical Roller Bearing 


2022-12-27

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