The bearing is an important supporting component between the stator and the rotor of the motor. It is used to ensure the uniform air gap of the motor and transfer the load. The correct selection and application of the bearing is an important part of the motor design. According to the different characteristics of the motor, such as the structure of the motor itself, the type of load, the working speed, etc., the bearing selection of the motor is also different. Only when the bearing is properly selected, the inherent characteristics of the bearing can be exerted and the reliable operation of the motor can be guaranteed.
Deep groove ball bearings and cylindrical roller bearings are the most commonly used bearing types for small and medium-sized motors and basic low-voltage high-power and high-voltage motors. The rolling element of the deep groove ball bearing is in point contact with the inner and outer rings of the bearing. It has low noise operation, low cost, can carry a certain range of radial load and axial load, low friction, low heat generation, high speed operation, etc.; its disadvantage is that it can not bear impact load, or radial and axial heavy load.
The rolling elements of the cylindrical roller bearing are in line contact with the inner and outer rings of the bearing. It has the advantages of being able to withstand radial heavy loads, and is widely used in large and medium-sized motors and large, medium and small motors with belt loads. Compared with deep groove ball bearings, the disadvantages are lower rated speed and higher noise.
Bearing working clearance
Bearing clearance is an important parameter in the use of motor bearings. If the working clearance is too small, it will cause heat or even high temperature to lock up. If the working clearance is too large, vibration will occur and the bearing life will be reduced.
The high bearing temperature and bearing noise are common problems encountered by motor manufacturers. In addition to the factors of the bearing itself, the machining quality, assembly process and component matching relationship of other parts related to the motor and the bearing will affect the final degree to varying degrees. Assembly effect.
Adjust and correct bearing working clearance
The non-backlash operation of the bearing is an ideal state that the assembly process strives to achieve. Some motor manufacturers use the actual matching method for the large-size motor to adjust the bearing working clearance, but take into account the tolerance zone of the special parts. The factor is that the good condition of the bearing clearance is higher by the actual matching method; if the axially acting spring element is used to adjust the bearing, the non-backlash operation can also be achieved, and the spring element is generally placed on the bearing cap and the axial swimming bearing. Between the outer rings.
In addition to the radial load, the motor bearing can withstand a certain two-way axial force under the condition of the motor.
Ball bearings are used for the bearings at both ends of the small motor. The problem of swimming must be considered. The medium-sized motor uses cylindrical roller bearings at the load end and ball bearings at the non-load end. Deep groove ball bearings are generally used as positioning end bearings and do not have the ability to move axially. Cylindrical roller bearings are mostly used on the load end, with large radial loads and axial travel characteristics.
Advantages of cylindrical roller bearings
Cylindrical roller bearing raceway and rolling element geometry have been improved, and have high load carrying capacity. The new structural design of the rib and roller end face not only improves the axial bearing capacity of the bearing, but also improves the roller end face. Lubrication conditions in contact with the ribs improve the performance of the bearing.
Cylindrical roller bearings are generally only used to withstand radial loads. The rollers are in linear contact with the ferrule raceways and are axially separable bearings. Compared to deep groove bearings of the same dimensions, cylindrical roller bearings have a large radial load capacity. Cylindrical roller bearings are easy to install and disassemble, impact resistant, and have good rigidity. The axial direction can generally be displaced in a limited amount, and cannot be independently subjected to axial load. Cylindrical rollers are in line contact with the raceway and have a high radial load capacity. They are suitable for both heavy and shock loads and for high speed rotation.
Advantages of deep groove ball bearings
Deep groove ball bearings have a wide range of applications; mainly used for high speed, high precision rotation and other working conditions. For example: CNC machining center spindle, grinding high-speed electric spindle, grinding wheel spindle, high-speed precision machinery. Sealed bearings with pre-filled grease are available. Deep-ball bearings are often used for two-head bearings of small motors. Medium-sized motors use roller bearings at the load end (as is commonly used for high-load conditions) and ball bearings at the non-load end. The advantages and disadvantages of motor bearing placement will directly affect the accuracy, life and performance of the bearing.