The rotor part of the motor product usually needs to be supported by two sets of bearings, and the rotor is radially and axially positioned relative to the stator. According to different use requirements, such as: load, required rotation accuracy, and manufacturing cost, etc., the bearing configuration of the motor generally adopts: one end fixed and one end floating; Floating "floating" configuration etc.
01 One end fixed and one end floating configuration
The fixed end bearing is fixed at the same time by the shaft and the bearing chamber of the end cover, which is radially supported at one end of the shaft and plays an axial positioning role in both axial directions. The bearing at the fixed end must be a radial bearing that can withstand combined radial and axial loads. The most commonly used deep groove ball bearings in motor products are double-row or paired single-row angular contact in some other equipment and machinery. Ball bearings and other bearings that can withstand combined loads.
For motors with three-bearing structure, the combination of bearings is used for positioning, that is, radial bearings that can only bear pure radial loads (cylindrical roller bearings with rings without ribs) and deep groove balls that can bear combined loads are used. Bearing combination. In this configuration, the other bearing, the deep groove ball bearing, is only used for axial positioning in two directions, and a certain degree of radial freedom must be left in the bearing chamber, that is, a clearance fit with the diameter direction of the bearing chamber.
The floating end bearing of the motor is on the other end of the shaft, and it is only radially supported, so the bearing of the floating end can be a deep groove ball bearing or a column bearing. Cylindrical roller bearings are used. In this configuration, the shaft must be allowed to have a certain axial displacement, so that there is no mutual force between the bearings. During the operation of the motor, when the shaft expands due to heat, axial displacement can be achieved inside some types of bearings (cylindrical roller bearings). Axial displacement can also occur between one of the bearing rings and the part to which it is connected, preferably between the bearing outer ring and the bearing chamber. In view of this, the choice of N-type or NU-type bearings requires the designer to carry out comparative analysis and demonstration.
There are many different combinations of fixed and floating bearing arrangements, the following are some of the more common combinations. For rigid bearing arrangements, combinations in which axial displacement can be achieved in the bearing should be used, such as: deep groove ball bearings combined with cylindrical roller bearings; double row angular contact ball bearings combined with cylindrical roller bearings; paired single row tapered rollers Bearings and cylindrical roller bearings are combined, and of course there are other combinations. For the design of this aspect, it is recommended to conduct joint analysis and selection with bearing manufacturers.
In the above combination, the angular error between the shaft and the housing must be minimized. If the application does not allow it, it is recommended to use a combination of self-aligning bearings that can withstand a larger angular error. These configurations can withstand a certain angular error and axial displacement, and can avoid internal axial forces in the shafting.
For the bearing configuration where the inner ring is subjected to rotational load, the length change of the shaft needs to be adjusted between the bearing and its mating surface, and the axial displacement should be between the outer ring and the bearing chamber. The most commonly used combination is deep groove ball bearing and deep groove ball bearing. Ball bearing; paired single row angular contact ball bearing and deep groove ball bearing combination, etc.
02Floating bearing configuration
The floating bearing arrangement is also a cross-positioning method, which is suitable for applications where only moderate axial positioning is required, or there are other components on the shaft for axial positioning. In this configuration, the most important thing is that each bearing can be displaced axially. It can be between one of the bearing rings and its mating surface, but preferably between the bearing outer ring and the bearing chamber.
03 Pre-adjusted bearing arrangements
In a pre-adjusted bearing arrangement, the shaft is axially positioned in one direction by one bearing and held by the other bearing in the other direction. This configuration is called "cross" positioning and is typically used for shafting of shorter lengths. All radial bearings capable of bearing axial loads (in one or both directions) are suitable for this configuration. In some cases, single row angular contact ball bearings or tapered roller bearings are used in cross-located arrangements, but some preload may be required.
No comments:
Post a Comment