At present, in engineering practice, people mainly choose to use deep groove radial ball bearings and tapered roller bearings. Tapered roller bearings are generally used in harsh working environments. In the design of the structure, the bearing usually adopts a large clearance ball bearing, and during operation, especially the horizontal roller, a lot of dry grease exists between the rolling elements and cannot be automatically discharged, thereby accelerating the wear of the bearing, and the service life is greatly reduced. In order to avoid this phenomenon and increase the load-bearing capacity of the idler, tapered roller bearings with large load-bearing capacity are used in the design calculation, so that the grease can be discharged automatically.
In general, we select and use 204 and 205 series rolling bearings. However, with the continuous emergence of special bearings, special bearings have been widely used, so the overall quality level of bearings can be greatly improved. After many test data, it is shown that even under very harsh conditions, the rotational resistance of the special bearing is low, and the experimental life is greatly increased, which can reach more than 10 times that of the 204 bearing. This shows that the use of special bearings for roller bearings can not only greatly improve the service life of the bearings, but also improve the overall quality of the roller bearings137.
Bearing is one of the important components of the roller, and its selection is appropriate, and the quality is very critical, which directly affects the service life of the roller. In the operation of the belt conveyor, the roller has a high rotational speed, which mainly bears the radial force and also bears a certain axial force. Considering the cost of the idler and the characteristics described above, deep groove ball bearings are usually chosen.
Excessive wear is the main form of failure of rolling bearings, and improper lubrication, improper lubricant type or composition are among the key factors causing excessive wear. Therefore, we must attach great importance to the selection of lubrication methods and lubricant varieties of rolling bearings.
From the perspective of lubrication, there are two ways:
(1) one-time oil lubrication, because this lubrication method in the roller in the middle and late stage of wear, its running resistance increases faster, and the life of the bearing is also shorter, so the long-term operation of the support is not suitable for this mode (2) can be oil-injected lubrication, the bearing can not only maintain a good lubrication state in this way, but also can eliminate the impurities in the bearing raceway. This method not only improves the service life of the bearing, but also maintains a constant resistance of the roller during operation.
Lubricants used in rolling bearings are divided into three main categories, namely oils, greases and solid lubricants, with greases being the most widely used. Considering the limitations of the roller structure and different use conditions, grease lubrication is generally used. There are usually three main types of greases commonly used in coal mining machinery: calcium-based greases, sodium-based greases and lithium-based greases.
