What are the effects of rotor imbalance on motor quality?

What are the effects of rotor imbalance on motor quality? Today we will analyze the vibration and noise problems caused by rotor mechanical imbalance.

1. Causes of rotor unbalanced vibration: residual imbalance during manufacturing, large amounts of dust attached during long-term operation, shaft bending caused by thermal stress during operation, unbalanced load caused by thermal displacement of rotor accessories, deformation or eccentricity caused by centrifugal force of rotor accessories, shaft bending caused by external forces (belts, gears, poor direct connection, etc.), and poor bearing installation (shaft accuracy or locking) causing shaft bending or internal deformation of bearings.
2. How to suppress the rotor imbalance: maintain it within the allowable imbalance, improve the excessive tight fit between the shaft and the core, improve the design for thermal expansion anisotropy, improve the strength design or assembly, modify the shaft strength design, change the type of shaft coupling and modify the center of the direct connection, and prevent the bearing end face from leaning against the shaft attachment or locking nut.

3. Causes of abnormal vibration and noise of bearings: damage inside the bearing, abnormal axial vibration of the bearing, excitation of the vibration system composed of axial spring constant and rotor mass; poor lubrication and bearing clearance of cylindrical rolling bearings or large-diameter high-speed ball bearings.

4. Bearing replacement: Appropriate axial spring preload changes the bearing clearance, select soft grease or grease with excellent low-temperature performance, and the residual clearance becomes smaller (pay attention to the temperature rise problem).
5. Rotor dynamic balancing correction method: After the dynamic balancing machine measures the rotor, the rotor can be balanced by adding weight or removing weight as needed: The so-called adding weight means adding a correction weight in the opposite direction of the imbalance. Common methods include welding, soldering, riveting, screwing, adding weight, etc. The removing weight method is to remove a certain amount of weight in the direction of imbalance. Common methods include: boring, drilling, chiseling, milling, grinding, etc.