Time: 2024-01-31
Source: TOOMOTOO
Author: TOOMOTOO
Click: 419 times
Bearings are important components in mechanical equipment. In order to ensure that the bearings can achieve ideal performance, correct installation and operation, and reasonable maintenance are very important. To extend the service life of bearings, three aspects of work need to be done.
First, lubrication is key
Proper lubrication and regular maintenance can avoid bearing damage caused by lubrication problems. To ensure reasonable lubrication, you should:
1. Follow the usage guidelines set by the device manufacturer for each device;
2. When adding grease, it should be filled between the rolling parts of the bearing and the shell (or retainer) to ensure that sufficient grease enters and the key raceway surfaces are fully lubricated;
3. Pay attention to when the bearing should be greased;
4. Monitor equipment’s indicating instruments to detect early signs of problems, such as temperature fluctuations and/or abnormally high temperatures;
5. Pay attention to equipment noise or abnormal vibration;
6. Observe lubricating oil leakage;
7. Sample the lubricating oil regularly and check for contamination.
Secondly, it is very important to make reasonable adjustments
If installed improperly, the bearing will not only vibrate, make loud noise, have low accuracy, increase temperature, but also be in danger of being stuck and burned; on the contrary, if installed well, not only the accuracy can be guaranteed, but the service life will also be greatly extended. Therefore, after the bearing is installed, it must be inspected.
Key inspection items are as follows:
1. Check the installation location
After the bearing is installed, first check whether the running parts and fixed parts collide, whether the lubricating oil can flow into the bearing smoothly, and whether the sealing device and axial fastening device are installed correctly.
2. Check radial clearance
In addition to installing bearings with pre-interference, the radial clearance should be checked. Deep groove ball bearings can be inspected by hand rotation. It is better to be stable and flexible, without vibration and without swinging left and right. Cylindrical rollers and spherical roller bearings can be inspected with a feeler gauge. Insert the feeler gauge between the roller and the bearing ring. The insertion depth of the feeler gauge should be greater than 1/2 of the roller length.
When the radial clearance of the bearing cannot be measured with a feeler gauge, the axial movement of the bearing can be measured instead of the reduction in radial clearance. Under normal circumstances, if the inner ring of the bearing has a tapered hole, the axial movement on the conical surface is approximately 15 times the reduction in radial clearance.
The radial clearance of bearings can be adjusted if they are not qualified after installation, such as angular contact ball bearings and tapered roller bearings; some have been adjusted according to standards during manufacturing and cannot be adjusted if they are not qualified after installation. Such as deep groove ball bearings, aligning ball bearings, cylindrical roller bearings, spherical roller bearings, etc.
If this type of bearing fails to pass the inspection after installation and the radial assembly clearance is too small, it means that the bearing fit is improperly selected or the assembly part is not processed correctly. At this time, the bearing must be removed, the cause must be identified, eliminated and then reinstalled. Of course, bearing clearance that is too large will not work.
3. Check the tightness between the bearing and the shaft shoulder
In general, bearings with a tight fit and interference fit must be close to the shaft shoulder. Testing method:
(1) Lighting method. Aim the light at the bearing and shaft shoulder to judge the light leakage. If there is no light leakage, it means the installation is correct; if there is light leakage evenly around the shoulder, it means the bearing is not close to the shaft shoulder, and pressure should be applied to the bearing to make it close; if there is partial light leakage, it means the bearing is installed tilted, you can use a hand hammer or a copper rod Or tap the sleeve on the inner ring of the bearing and slowly straighten it.
(2) Thickness gauge inspection method. The thickness of the thickness gauge should start from 0.03mm. During the inspection, try inserting several points on the end face of the bearing inner ring and the entire circumference of the shaft shoulder. If there is a gap and it is very uniform, it means that the bearing is not installed in place, and the inner ring of the bearing should be pressurized to make it close to the shaft shoulder;
If it is not tight even if the pressure is increased, it means that the fillet of the journal fillet is too large and the bearing is stuck. The journal fillet should be trimmed to make it smaller; if it is found that the end face of the inner ring of the bearing and the bearing shoulder are found to be If the thickness gauge can pass, it means that it must be disassembled, repaired and reinstalled.
If the bearing is installed in the bearing seat hole with an interference fit and the outer ring of the bearing is fixed by the housing hole shoulder, whether the end surface of the outer ring is close to the housing hole shoulder end surface and whether the installation is correct can also be checked with a thickness gauge.
4. Inspection of thrust bearing after installation
When installing a thrust bearing, the verticality of the shaft ring and the shaft centerline should be checked. The method is to fix the dial indicator on the end face of the box shell, so that the contact head of the dial is on the raceway of the bearing shaft ring and rotate the bearing while observing the dial indicator pointer. If the pointer is deflected, it means that the shaft ring and the center line of the shaft are not perpendicular. When the hole in the box shell is deep, an extended dial indicator can also be used for inspection.
When a thrust bearing is installed correctly, its seat ring can automatically adapt to the rolling of the rolling elements to ensure that the rolling elements are located in the upper and lower raceways. If installed upside down, not only will the bearing not work properly, but also the mating surfaces will be severely worn. Since the difference between the shaft ring and the seat ring is not very obvious, extra care should be taken during assembly to avoid making mistakes.
In addition, a gap of 0.2-0.5mm should be left between the thrust bearing seat ring and the bearing seat hole to compensate for errors caused by inaccurate parts processing and installation. When the center of the bearing ring deviates during operation, this gap will This ensures that it adjusts automatically to avoid contact and friction, allowing it to operate normally. Otherwise, severe damage to the bearing will occur.‘
5. Check whether the bearing noise, temperature rise and vibration meet the requirements.
Generally, the operating temperature of bearings should be lower than 90°C. When the temperature is too high, it will cause the bearings to heat up, anneal or burn out, reducing their service life.
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Harber Metal