1、 Abstract

The double row angular contact ball bearing can bear radial load and axial load acting in two directions. It can limit the axial displacement of shaft or shell in two directions. The contact angle is 30 or 35 degrees. It can provide high rigidity bearing configuration and can withstand overturning moment. Therefore, it is usually selected as axial positioning role in rolling mill roll system (operation side). It is usually composed of inner ring, outer ring, rolling element and cage. The main function of the cage is to divide the rolling element equally and limit the proper operation of the rolling element in the channel. During the operation process of 4024d (double row angular contact ball bearing) in the middle roll operation side of a customer's six high cold rolling mill, abnormal damage often occurs to the bearing cage, which seriously affects the normal production.

2、 Damage phenomenon

It is mainly due to the wear and fracture of cage at high temperature (over 80 degrees at the gland of positioning bearing) during high-speed operation, resulting in locking and adhesion, and damaging roll diameter and bearing box hole in serious cases, resulting in great economic loss and human and material resources consumption.

3、 Cause analysis

1. Bearing angle consideration

Generally speaking, when the speed of rolling mill is close to the limit, the speed of bearing will be too high or the speed will be too low. In this incident, all the bearing damage was concentrated on the operation side, and the bearing on the transmission side used the same batch of bearings, and the above problems were not found under the same rotating speed and lubrication conditions, and they could operate normally. Therefore, the bearing damage caused by the bearing itself can be ruled out temporarily.

2. Dimensional fit

The angular contact ball bearing is installed on the operation side of the roller system. The axial movement of the main limit shaft should not bear any radial load. The outer diameter and the box aperture should be matched with F7, the inner diameter and shaft diameter should be matched with E6. The main bearing is C3 group radial clearance. According to the calculation, all the bearings will be distributed to the main bearing after being subjected to radial force during operation The angular contact ball bearing does not bear any negative radial load but only axial load. Therefore, it can be ruled out temporarily that the bearing damage is caused by the size matching problem.

3. The matching problem of end contact parts

After careful inspection of the end faces of the inner and outer rings of the bearing, it is found that the damaged bearings basically have abnormal wear on the end faces, and the cages also have serious wear traces. Further check the end faces of the mating parts contacted with them, mainly including the end face of the outer ring gland extension, the end face of the distance ring connecting the inner ring, and the convex end face of the outer ring of the positioning bearing with holes in the box. It can be judged that there is serious relative sliding friction between the bearing and the mating contact parts during operation. After measurement and installation, the outer ring of the bearing is not compressed axially, there is a gap of 0.5-0.7mm, and there is also a large axial clearance after the inner ring is locked. Therefore, the bearing has a large axial movement during operation. Due to the lower hardness of the accessories than the bearing, it is easy to be worn irregularly Due to the axial force in a certain direction, when the end face is close to the contact surface of the opposite mating part (the end face has been irregularly worn), the inner and outer rings of the bearing are inclined relatively. Therefore, the higher the speed, the irregular operation of the rolling element will result in larger clamping force and frequent impact force on the cage, which will lead to the wear and fracture of the cage.

4、 Conclusion

From the above analysis, we can temporarily judge that the axial fit after installation, the contact fitting in use and the bearing damage caused by the main factors.

And why there is no such phenomenon in the drive side bearing Welcome to leave a message for discussion.

5、 Rectification measures

Call the DMD bearing.