For centrifugal pumps, unbalance refers to components that make rotational motion, such as various drive shafts, spindles, fans, pump impellers, rotors for electric motors and steam turbines, mass eccentricities, or failures caused by defects in rotor components.
The reasons for the unbalance are roughly divided into the following categories:
1. The shape of the rotating piece itself is asymmetrical
2, manufacturing tolerances
3, improper assembly and installation
4. Deformation when the rotating part is running
5, the broken parts wear and tear
6, the rotating parts attached to foreign objects
Unbalance can be divided into static imbalance, even imbalance, and dynamic imbalance according to its mechanism.
Static unbalance: There is an unbalanced mass in the center plane of the rotor, which makes the center line of the shaft deviate from the center line of rotation, but the two lines are parallel.
Even unbalance: There are unbalanced masses of equal mass and 180 degrees out of phase at the planes at both ends of the rotor, so that the center line of the shaft intersects the center line of rotation at the center of gravity.
Dynamic unbalance: A random combination of static imbalance and moment imbalance, the centerline of the shaft is not parallel or intersected with the centerline of rotation.
Correction
Unbalance can be used to perform on-line dynamic balancing correction with dynamic balance system and dynamic balance meter.
