1  Unit parameters

Rolling Mill model: 1450 eight high single unit *** High line speed: 600m/min

Product type: stainless steel strip Common rolling force: 10000KN Lubrication method: rolling oil lubrication

Support roller bearing model: FCDP120184680

2 Support roller bearing structure and characteristics

As a typical rolling mill roller bearing, the FCDP cylindrical roller bearing can provide the largest radial load capacity and lower friction coefficient compared with other types of bearings in a given installation space. The bearing consists of two outer rings, two inner rings and four rows of roller components. The roller assembly consists of 2 washers, 1 column of pillar, 1 column of hollow rolling body, the pillar passes through the rolling body, one end is threaded with the washer 1, and one end is welded with the washer 2. The clearance between the end face of the roller and the two gaskets is set at 1.2-2mm, and the cage can be axially displaced when the bearing is running at high speed.

3 Assembly structure

The maintenance inspection of the lower support roll bearing on the operating side of the rolling mill during the first cycle (about 25 days per cycle) found that the end face of the cage washer 1 was seriously worn, and the end face of the bearing rolling body was also worn, resulting in the final scrap of the bearing.

4 Site damage phenomenon

1.bearing maintenance found that the end face of the washer 1 serious wear;

2.the corresponding distance ring 2 end face is also seriously worn;

5 Reason analysis

In summary, the judgment described in two, three and four: the bearing damage is caused by interference between the end face of the washer 1 and the corresponding end face of the distance ring, resulting in wear and tear, and eventually causing the bearing to fail and be scrapped. From the analysis of the assembly structure, the main reasons for interference between the end face of the washer 1 and the corresponding end face of the distance ring are as follows:

1. The end face of the distance ring 1 is worn, and the overall width becomes smaller, resulting in the axial displacement to the right of the entire bearing housing and the bearing outer assembly relative to the roll;

2. There is a gap when the outer gland locks the positioning bearing outer ring;

3. There is a gap when the lock nut locks the positioning bearing inner ring;

4. The clearance between the end face of the washer 1 and the corresponding end face of the distance ring is too small, and any small axial displacement will cause the risk of interference.

6 Further comparative analysis of data

By viewing the CAD structure drawing and related parts drawing, the data is sorted out as follows:

1. Four-row cylindrical bearing FCDP120184680, after comparison and measurement calculation, the end face of the cage washer 1 and the end face of the bearing outer ring *** small clearance 2mm;

2, the installed roll assembly, after comparison and measurement calculation, the end face of the washer 1 and the distance ring 2 corresponding to the end face *** small spacing 2.5mm;

By comparing and measuring the size of the relevant parts of the damaged roller system, it is found that the width of the distance ring 1 compared with the drawing is shortened by 2.1mm due to wear.

At the same time, the outer ring face of the external gland locking positioning bearing is worn, indicating that the outer ring of the positioning bearing is not locked, and the measured clearance is 0.8mm after restoration installation.

3. By comparison, it is found that the total relative axial displacement exceeds the minimum distance of 2.5mm between the end face of the washer 1 and the end face of the distance ring 2, that is, there is an interference amount of -0.4mm.

7 Preventive and improvement measures

1. Ensure the reliability of axial locking during installation;

2, regular measurement of axial positioning parts to prevent changes in size;

3. Amplify the safety distance of axial interference, such as the small spacing between the end face of the washer 1 and the end face of the distance ring 2.