Because many machine structures are relatively complex, multiple sets of bearings are required for combination. This is a combined bearing. Rolling bearing composed of two bearing structures combined in one set of bearings. Such as needle roller and thrust cylindrical roller combined bearings, needle roller and thrust ball combined bearings, needle roller and angular contact ball combined bearings, etc.
Among them, roller bearings are widely used. The unique feature of its design is the use of short cylindrical, conical or waist drum rollers as rolling bearings for rolling elements. Mainly used in the following fields: textile machinery, printing machinery, automobile industry, household appliances, money detector.
1. The combined form of combined bearings
1. Combined needle roller and thrust ball bearings without inner ring
2. Combined needle roller bearing without inner ring and thrust ball with outer cover
3. Combined needle roller bearing with inner ring and thrust ball with outer cover
4. Combined needle roller and angular contact ball bearings
5. Combined needle roller and three-point contact ball bearings
6. Needle roller and thrust cylindrical roller combined bearings without inner ring
7. Needle roller without inner ring and thrust cylindrical roller combined bearing with outer cover
8. Combined bearing with inner ring needle roller and thrust cylindrical roller
9. Thrust cylindrical roller combined bearing with inner ring needle roller and outer cover
10. Needle roller and bidirectional thrust cylindrical roller combined bearing
11. Combined bearing with flange needle roller and bidirectional thrust cylindrical roller
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2. Adjusting the clearance of combined bearing
In order to ensure the normal operation of the bearing, there is usually a proper axial and radial clearance inside the combined bearing. The size of the clearance has a great influence on the rotation accuracy, load, life, efficiency and noise of the bearing.
If the clearance is too large, the rotation accuracy of the bearing is reduced, and the noise is increased; if the clearance is too small, the bearing is loaded due to the thermal expansion of the shaft, the life is shortened, and the efficiency is reduced. Therefore, when assembling the bearing assembly, the clearance should be adjusted appropriately according to the actual working conditions, and the structure can be easily adjusted.
There are three common methods for adjusting play:
(1) Gasket adjustment
For the angular contact bearing assembly shown, the clearance can be adjusted by increasing or decreasing the thickness of the gasket set between the bearing cap and the bearing housing. The thermal compensation gap of the deep groove ball bearing combination is also adjusted by the gasket.
(2) Screw adjustment
Adjust the bearing clearance with screws and dish-shaped parts, and the nuts play a locking role. This method is easy to adjust, but cannot withstand large axial forces.
(3) Round nut adjustment
Two tapered roller bearings have reverse mounting structure, and the bearing clearance is adjusted by a round nut. But the operation is not convenient, and the thread will weaken the strength of the shaft.
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3. The effect of temperature on the efficiency of combined bearings
The combined bearing will heat up after it starts to operate, and after a period of time, it will be in a normal state at a lower temperature (usually 10 to 40 degrees higher than room temperature). The time to normal state depends on the size, form, rotation speed, and lubrication method of the bearing and the heat release conditions around the bearing. At this time, it takes about 20 minutes to several hours.
When the combined bearing temperature does not reach the normal state and abnormal temperature rise occurs, the following main reasons can be considered:
1. Too much or too little lubricant
2. Poor installation of bearings
3. The internal clearance of the combined bearing is too small, or the load is too large
4. Excessive friction of the sealing device
5. Lubricants do not match
6. Creep of the mating surface
In addition, if the above situation occurs, it should be shut down as soon as possible and take necessary countermeasures. Temperature is essential to maintain the proper life of bearings and prevent the deterioration of lubricants!
Suggestion: Try to control under the non-high temperature state (generally below 100 degrees) to use the most ideal.
Second, check the raceway surface of the bearing, the condition of the rolling surface and the joint surface, and the wear and tear of the confrontation frame. Whether there is any damage or abnormal conditions is especially to check the running track of the raceway surface. To determine whether the bearing can be used again, it is necessary to think about the level of damage to the combined bearing, mechanical function, priority, operation premise, search and inspection cycle, etc., and then choose.
When replacing the combined bearing, the new bearing should be carefully inspected. At the same time, the shaft diameter, the bearing seat hole and the rotor should be carefully inspected, and when the bearing is assembled and disassembled, the maintenance process should be strictly carried out and the operation should be carried out carefully to avoid the improper assembly and disassembly. The bearing is damaged. Add oil and change oil on time to ensure that the working condition of the bearing is always in good condition; check it carefully during the operation of the combined bearing, find the hidden trouble of the failure, and eliminate it in time.
Eric Bearing Limited has been engaged in international trade for more than ten years. It has cooperated with distributors of major bearing brands. The products have sufficient inventory to ensure customer needs. If you have needs, please contact us as soon as possible. Will definitely meet your needs and give you the best price.