During assembly, the bearing outer ring and bearing seat hole or the bearing inner ring and shaft are not properly matched....
1、 Causes of bearing heating and locking
1) During assembly, the bearing outer ring and bearing seat hole or the bearing inner ring and shaft are not properly matched.
During the assembly process, sometimes the inner hole is not repaired and its size is not measured, and the bearing is replaced for assembly. After the test run, it is found that the temperature rise is too high. During the inspection and measurement, it was found that the bearing seat hole had been deformed, causing the outer ring of the bearing to be squeezed, resulting in smaller radial clearance of the bearing, uneven rotation of its rolling body and increased wear. The clearance between the bearing inner race and the shaft is too large. The bearing inner race rotates with the rolling body and the shaft, and friction causes the bearing to heat and vibrate.
2) Improper control of bearing heating temperature or uneven heating during assembly may cause bearing deformation.
If the temperature of the commissioning bearing heater is too high during the heating operation, it will backfire and reduce the hardness and precision, which will increase the bearing temperature and cause the bearing to wear and damage. Due to uneven heating, the bearing has deformation, uneven clearance and local high temperature.
3) Improper adjustment of bearing clearance during assembly.
In practical work, many installations are sometimes debugged only by hand feeling, and the gap is too large or too small to meet production needs. If the axial clearance is too small, it is easy to cause bearing heating, accelerate pitting, and even make the rolling body stuck or damaged by gluing; If the axial clearance is too large, the impact force of the moving pair will increase and the stiffness will decrease, which will cause abnormal noise in operation, and even cause serious vibration or damage to the cage.
4) Oil seal problem: oil seal is a sealing element used to seal the rotating shaft in mechanical equipment, and the cavity is basically static, so oil seal is also called the rotating shaft lip seal ring. For the oil seal with the auxiliary lip, the auxiliary lip plays a dust-proof role to prevent the invasion of impurities, so as to prolong the service life of the oil seal. However, the auxiliary lip is often poorly lubricated and the friction force is large, resulting in the damage of the oil seal due to dry friction. Therefore, when installing the double-lip oil seal, be sure to fill the grease between the two lips.
5) For thermal equipment, the thermal expansion and contraction of the shaft are not considered during installation, and the free end shaft is subjected to extrusion during operation, resulting in huge heat.
6) Clearance problem
During the assembly process, if the size of the spacer sleeve is not carefully calibrated and the assembly and test run are carried out, the temperature will rise rapidly after a certain time. The size of the outer ring of the bearing has been determined by the end cap and the bearing seat. The size of the spacer sleeve is reduced, and the size of the inner ring will be adjusted by the round nut. Finally, the axial clearance of the bearing will be reduced, making it hot during operation.
7) Lubrication problems
The lubricating grease in the bearing should not be too much. Too much grease will increase the friction torque and the bearing temperature; If the amount of grease is too small, reliable lubrication will not be obtained and dry friction will occur. Generally speaking, the appropriate amount of grease is 1/3~1/2 of the total clearance volume in the bearing. Therefore, an appropriate amount of grease should be injected regularly according to the use requirements.
The oil is interrupted during the operation of the equipment, and the bearings that lose lubrication and cooling are heated, which will soon be damaged.
2、 Treatment of bearing locking
For the locking of bearings, first of all, strictly check the installation, lubrication, cooling and heat dissipation, ensure the shape and tolerance size of the containing parts, and the bearing quality, and strictly follow the instructions or maintenance plan to avoid the locking of bearings. In case of lock-up, the inner sleeve of the bearing must be cut off first, then the axle, and the method of coating or other methods must be used. Restore the size and tolerance of the shaft, and then reassemble it as required. If the shaft is very important, flaw detection must be carried out to ensure the quality of the shaft. If necessary, the shaft must be replaced.
