Ms. Can's friend told me that their company produced a YE3-355-4 export vertical motor , but due to excessive vibration and noise, it did not meet the testing requirements and was not allowed to leave the factory. After consultation and discussion among the company's experts, it was decided to make some minor adjustments to the motor's axial direction. Upon retesting, all the original faults were eliminated. Ms. Can then discussed the characteristics of large-size vertical motors, sharing her experience and insights with everyone.
The special characteristics of vertical motor structure
Compared to horizontal motors, vertical motors, especially large-sized vertical motors, have unique bearing systems, typically using angular contact ball bearings at one end. Due to the special structure of angular contact ball bearings, it is crucial to avoid incorrectly installing them in the wrong orientation; otherwise, the bearing will be rendered unusable. If the bearing is not properly seated or if the axial fit of the bearing is misaligned during motor operation, it may cause abnormal vibrations and unusual noises in the motor.
Features of angular contact ball bearings
Single-row angular contact ball bearings are designed for combined loads and can handle large thrust in one direction. Most vertical motors use a single-row angular contact ball bearing at the non-shaft extension end for axial forces high enough to exceed the axial force that deep groove ball bearings can withstand. They are interchangeable in size with the single-row deep groove bearings of the corresponding motor, avoiding a series of unforeseen problems that would arise from redesigning structural components.
Angular contact ball bearings are also commonly used in applications with large axial forces, such as gear reducers, pumps, worm gear drives, vertical shafts, and machine tool spindles. In these applications, they are often installed in various pairs.
Loading method of angular contact ball bearings in vertical motors
In vertical motors, angular contact ball bearings are used to apply an axial force that balances the weight of the motor rotor, ensuring a balanced axial position between the rotor and stator. When the angular contact ball bearing is located below the motor rotor, it is a lifting mechanism; when it is located above the motor rotor, it is a suspension mechanism.
Why is misalignment of the bearing itself prone to occur?
Regardless of whether the motor is installed using a lifting or suspension method, during operation, in addition to the inherent matching relationship of the axial dimensions, the stator and rotor magnetic center lines spontaneously align under the influence of electromagnetic force after the motor is powered on. This may lead to axial displacement of the rotor. Due to unavoidable cumulative errors in the machining of components and overall assembly deviations, the actual displacement will cause varying degrees of axial misalignment of the bearing itself. When the bearing misalignment is severe, the spontaneously aligning electromagnetic force and the rotor's weight become a reciprocating excitation force, exacerbating bearing noise and vibration.
Response measures
In the motor design phase, the bearing stress conditions should be carefully analyzed, and potential axial excitation forces should be fully considered. Special attention should be paid to the selection of motor bearing structures, such as the paired use of angular contact ball bearings, axial stopping and control of bearings, the adoption of a three-bearing structure, and appropriate pre-misalignment of the motor stator and rotor. Among these, the pre-misalignment dimensions of the motor stator and rotor must be precisely controlled; otherwise, the results will be counterproductive.
It is particularly important to note that during the storage, transportation, and testing of vertical motors, the motor must be kept in the correct vertical position to avoid generating harmful external forces that could damage the bearings.
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