After receiving the notification from your company, the business manager and technical personnel arrived at the site for on-site inspection. Through the on-site inspection of the damaged bearings and the introduction of the person in charge, the site situation was understood as follows:

Bearing model: FCDP110160560

Use position: support roll

Use problem: the rolling element is damaged

1 Bearing structure and performance

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, four rows of roller assemblies, and two inner rings. The outer ring clearance is installed in the bearing seat, and the inner ring interference is installed in the diameter of the roll, which mainly carries all the radial load during rolling. It is used in the support roll system of the metallurgical calendering machine. Because it cannot bear the axial load, it cannot be used alone, and it needs to be used with positioning bearings, with high bearing manufacturing accuracy and high installation accuracy.

1, does not have aligning performance, more sensitive to tilt and cross;

2, the box requires high accuracy, especially the taper of the box hole, such as the taper is out of whack, will directly affect the force distribution;

3, the inner ring and the shaft are required to have a height concentric and the diameter difference between the two ends is strictly required, generally not more than 0.02mm;

2 Through customer feedback and disassembly inspection, the main damage characteristics of bearings were found as follows:

1. The breakage of the middle two columns of rolling element corresponds to the breakage of the cage;

2, there is A significant difference in the size of the covering Angle trace of the outer diameter load zone of the outer ring A and the outer ring B;

The outer diameter load zone covering Angle mark of outer ring B is about 160°, while the outer diameter load zone covering Angle mark of outer ring A is about 90°.

3. There is also A significant difference in the covering Angle of the load zone of the raceway corresponding to the first column of the outer ring A and the fourth column of the inner raceway corresponding to the outer ring B;

Outer ring A, column 1, inner raceway load zone covering Angle mark about 75° Outer ring B, column 4 load zone covering Angle mark about 180°.

4, the middle row of rolling body end face friction is serious, there are visible cracks and burns, individual rolling body fragmentation;

5. The whole circumference of the outer ring rib face is seriously worn;

6. The two ends of the septum ring are seriously worn, the outer diameter has circumferential friction marks, and a cracking occurs;

There are obvious friction marks in the circumference direction of the outer diameter of the septum ring, serious friction between the contact points of the two end faces and the end faces of the rolling body, friction cracks and local falling blocks in the whole circumference.

3 Cause analysis

From the above picture and combined with the service cycle, bearing force characteristics and wear state of each part, the analysis is as follows:

(1) The covering Angle of the load zone of the inner and outer rings is about 160° in the outer diameter load zone of the outer ring B, and about 90° in the outer diameter load zone of the outer ring A; The covering Angle mark of raceway load zone in the first column of outer ring A is about 75°, and the covering Angle mark of raceway load zone in the fourth column of outer ring B is about 180°. The covering Angle directly reflects the stress condition and working clearance state of the bearing during operation, and from the current covering Angle size of the bearing, it can be directly judged that there is serious clearance deviation in the running state of the bearing. That is, the working clearance of the first column is much greater than that of the fourth column, and the stress state of the fourth column is much greater than that of the first column, which results in the serious load bias problem of the bearing, which leads to the linear decline of the bearing bearing capacity and the deviation of the running track of the rolling element, resulting in problems such as end friction and axial load.

(2) The end face wear and cracking of the rolling body, as well as the corresponding outer ring rib wear and the corresponding cage damage problem, the role of the cage in the bearing is mainly to divide the rolling body equally, so that the rolling body is evenly distributed on the circumference of the bearing inner ring and the outer ring to ensure the uniform bearing load. The operation is passive operation, mainly driving the inner ring when the roll rotates, and the inner ring drives the rolling body to run. The rolling body drives the cage to operate, and the damage is often caused by shear stress. When the rolling body is deflected, the torque load is formed relative to the cage, which leads to its damage. However, the biased load force and the serious wear of the end face of the rolling body and the end face of the baffle will inevitably lead to the deflected operation of the rolling body.

(3) The wear problem of the spacer ring, there are obvious friction marks in the circumference direction of the outer diameter of the spacer ring, the contact point of the two end faces and the end face of the rolling body has serious friction, and the entire circumference has friction cracks and local falling blocks. In the bearing structure, the outer diameter of the spacer is smaller than the outer diameter of the bearing and does not bear radial load. It mainly blocks the end face of the rolling body, guides its running track and ensures that the lubricating oil passes through the oil hole where the outer diameter is evenly distributed. After installation, the end face is in close contact with the end face of the outer ring of the bearing. It indicates that there is creep phenomenon or the problem of fitting with the outer ring. In addition, the cracking of the spacer also indicates that the end face is seriously worn and bears the axial force of the rolling body when it runs sideways.

4 Corresponding elimination measures

1. Measure the outer diameter of the bearing inner ring before installation to ensure that the outer diameter of the four columns inner ring is within the range required by the drawing;

2. Measure the bearing seat aperture before installation to ensure that the aperture is within the range required by the drawing;

3. Strictly implement the size of the bearing drawing to ensure that the clearance, size, etc. meet the requirements of the drawing;

4, the first installation joint users to complete;