The most commonly used bearings in motors-deep groove ball bearings
The most commonly used type of bearings in motors are deep groove ball bearings. In the field of industrial motors, the use of deep groove ball bearings accounts for more than 70% of the total use of bearings. If it is used in terms of quantity, its proportion will be even greater. Therefore, if electrical engineers are familiar with deep groove ball bearings, they can understand the application of motor bearings to a large extent.
Deep groove ball bearings, the previous domestic standard is called radial ball bearings. As the name implies, this type of bearing is a type of rolling bearing that bears centripetal load and the rolling elements are spherical. The centripetal load mentioned here is the so-called radial load. Therefore, the main load bearing capacity of deep groove ball bearings is in the radial direction.
At the same time, due to the structural characteristics of the channel, the bearing can bear a certain axial load. The axial load capacity of deep groove ball bearings is much weaker than the radial load capacity. Therefore, it is necessary to check the life of deep groove ball bearings under axial load conditions to ensure that the bearings can achieve the expected results of operation under this load.
Compared with roller bearings, deep groove ball bearings have point contact between the internal rolling elements and raceways. Let’s briefly analyze the characteristics and limitations of deep groove ball bearings.
Features of deep groove ball bearings
01. The ability to withstand radial loads is weaker than roller bearings
The load carrying capacity of deep groove ball bearings is smaller than that of corresponding roller bearings, but they are sufficient for general industrial motors. Often for working conditions with extra radial load such as an external pulley, the load capacity may not meet the requirements. In this case, cylindrical roller bearings can be used.
02. The internal friction of the bearing is relatively small, and the heat is small
The rolling element and the raceway are in point contact, and the internal heating of the bearing is relatively small. If it is a bearing with a seal, the friction and heating of the seal should be considered during operation.
03. High speed of bearing
The inner rolling elements of deep groove ball bearings are balls. Compared with roller bearings, the mass of rolling elements is relatively small, and the centrifugal force during high-speed rotation is small. The commonly used stamped rigid cages and nylon cages have better strength, so The mechanical limit speed capability of deep groove ball bearings is relatively high. Correspondingly, due to the relatively low heat generation, the thermal reference speed capability of deep groove ball bearings is relatively high.
04. Simple bearing arrangement
Deep groove ball bearings can bear both axial load and radial load, so this type of bearing can be used as either a locating end bearing or a non-locating end bearing.
05. Easy to use, convenient for storage and transportation
Deep groove ball bearings are usually a one-piece bearing structure, so the installation, storage and transportation of the bearing are easier than split bearings.
06. Simple maintenance
Usually deep groove ball bearings are available in open type, with dust cover and with seals, which greatly simplifies the workload of bearing relubrication and has the characteristics of simple operation.
The limitations of deep groove ball bearings
Deep groove ball bearings also have their own limitations due to their structural characteristics:
General deep groove ball bearings have very limited eccentricity adjustment capabilities, generally within a range of less than 10 arc minutes. This eccentricity is brought about by its own structure and clearance, and is not reserved for application conditions. Therefore, it is not recommended for electrical engineers to use this eccentricity.
2. Damage in bearing installation
The inner part of deep groove ball bearing is in point contact, so it is very easy to get injured during installation. Therefore, when installing the motor bearing, it is necessary to prevent the installation force from causing raceway damage through the rolling elements.
3. Temperature limit
Generally, the heat treatment dimensional stability temperature of deep groove ball bearings without special instructions is 120 degrees Celsius. Therefore, deep groove ball bearings are not suitable for operation at temperatures higher than this temperature.
At the same time, when selecting deep groove ball bearings under high temperature conditions, the temperature limits of lubricants, cages and seals need to be considered. (Please refer to related articles in the official account)
4. Application under vibration conditions
Deep groove ball bearings are prone to damage the raceways and rolling elements under vibration conditions. Therefore, deep groove bearings will encounter certain challenges under vibration conditions.