Double row angular contact ball bearings can withstand radial loads and axial loads acting in both directions, it can limit the axial displacement of the shaft or housing in both directions, the contact angle is 30 or 35 degrees, can provide a more rigid bearing arrangement, and can withstand the overturning torque, so it is usually selected in the rolling mill system (operating side) for axial positioning. It is usually composed of four major parts: inner ring, outer ring, rolling element and cage. Among them, the main role of the cage is to equally spaced rolling elements and limit the rolling elements to operate correctly in the channel. Let's take a look at the damage to the double row angular contact ball bearing cage with xiaobian?
Mainly when running at high speed, there is a high temperature phenomenon (more than 80 degrees at the positioning bearing gland) The cage wears and breaks, which eventually leads to lock and stick, and when it is serious, the roll diameter and bearing box hole are damaged, resulting in greater economic losses and manpower and material resources.
Cause analysis of double row angular contact ball bearing cages:
1. Consider the angle of the bearing itself
In general, the bearing rotation accuracy is low, the clearance is small, the rolling mill line speed is high, the speed of the bearing is close to the limit speed or exceeds the limit speed, which will lead to the high temperature of the bearing, and then the abnormal sound, locking, adhesion and so on will occur. In this incident, the damaged part of the bearing was concentrated on the operating side, while the transmission side bearing used the same batch of bearings, which could operate normally without the above problems at the same speed and lubrication conditions. Therefore, bearing damage caused by the bearing itself can be temporarily excluded.
2. Size fit
This angular contact ball bearing is installed on the operating side of the roller system, the axial movement of the main limit shaft, should not be subject to any radial load, the outer diameter and the box aperture are selected F7 fit, the inner diameter and shaft diameter are selected e6 fit, the main bearing is the C3 group radial clearance, after accounting for this fit, after the bearing is run by the radial force, the part is distributed to the main bearing, and the angular contact ball bearing does not bear any negative plus radial load, only bears the axial load. Therefore, bearing damage caused by size fit problems can be excluded for the time being.
3. The problem of surface contact parts is compatible
Carefully check the bearing inner and outer ring surface, damaged bearings basically have abnormal wear phenomena, the cage also has serious wear marks, progress to see the contact with the mating parts surface, mainly the outer ring gland extension surface, the fixed distance ring surface connecting the inner ring, the box inner bore positioning bearing outer ring of the boss surface there is abnormal wear, the surface is now pit bumps.
It can be judged from this that there is a serious relative sliding friction between the bearing and the mating contact parts during operation, and the bearing outer ring is not pressurized axially after measurement and installation. There is a 0.5-0.7mm clearance, the inner ring locking also has a large axial clearance, so the bearing has a large axial movement during operation, because the fittings are lower than the bearing hardness, it is easy to be irregularly worn, when the bearing is subjected to an axial force in a certain direction, the face is close to the opposite mating (at this time the surface has been irregularly worn) when the contact surface of the bearing inner and outer rings is relatively inclined.
Therefore, the faster the speed, the irregular operation of the rolling elements, the large clamping force on the cage, and the frequent impact force, which then causes the wear and fracture of the cage.