The three-phase asynchronous motor rotor imbalance is a failure caused by the eccentricity of the rotor component or the defect of the rotor component. It is a common failure of rotating machinery. According to statistics, about 70% of the faults of rotating machinery are related to the unbalance of the rotor. Today, the editor of Dalan Motor leads everyone to see what causes the rotor imbalance.
1. Design issues:
(1) The geometric design of the rotating body is asymmetric, and the center of gravity is not on the axis of rotation.
(2) There are unprocessed surfaces inside or outside the motor rotor, causing uneven mass distribution.
(3) The mating surface of the part on the rotating shaft is rough or the tolerance is not suitable, resulting in radial or axial swing. When the fit is too loose, the inner bore of the rotor expands at high speeds causing eccentricity.
(4) The mating key on the shaft is installed in the key groove, forming a partial metal vacancy.
(5) The rotating parts on the shaft are not installed symmetrically, and there is a fit clearance.
2. Material defects:
(1) The casting has air holes, resulting in uneven internal structure of the material and inconsistent thickness of the material. For example, the welded structure has asymmetric quality due to different thicknesses.
(2) The material is poor, and it is easy to wear and deform, resulting in uneven mass distribution.
3. Processing and assembly errors:
(1) Modeling defects in welding and casting.
(2) Cutting error during cutting.
(3) The accumulation of matching errors during assembly of the impeller causes a shift in the center of gravity. Therefore, dynamic balancing is required for each impeller installed on the high-speed rotor.
(4) The heat treatment of the material does not meet the requirements, or the residual stress does not eliminate the distortion during processing and welding, which permanently deforms the rotor.
(5) Inconsistent mating parts cause asymmetric quality. Such as: the depth of the screw hole or the length of the screw is inconsistent.
(6) The coupling is misaligned. For one of the rotors, a parallel misalignment is equivalent to adding an unbalanced load to the rotor. Therefore, it also shows unbalanced characteristics.
Fourth, the method of dynamic balance is wrong: for a flexible rotor, the vibration mode at the working speed is significantly different from the first-order vibration mode. Therefore, the rotor is balanced only at low speeds, and large vibrations still occur at high speeds.
----- Responsible Editor: Dalan Oil Pump Motor 02-Procurement Consultant
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