Causes of multistage pump shaft bending

The bending of the pump shaft of the multistage pump is usually caused by frequent vibration, bearing misalignment, and friction between static and dynamic, which will produce a series of problems, such as the wear of the mouth ring, shaft sleeve, impeller, etc., which leads to the uneven clearance between the balance disc and the balance drum, destroying the liquid film, resulting in dry friction, causing the failure or wear of the balance device. This causes the pump shaft to bend.

Pump shaft bending causes:

1) Improper turning

Because there is no common-sense rotation of the centrifugal pump before starting the pump, it will cause hot bending of the rotor, and if the pump is forcibly started, it will cause strong vibration and even become permanent bending.

2) Improper clearance

The gap between the various flow parts of the multistage pump is not adjusted, and the gap is too small, which causes the friction of the parts in operation, and the rotor heat obviously causes the rotor of the pump to bend.

3) The set impeller is loose

If the impeller is obviously loosened, the thermal resistance will change, which causes the temperature of the part of the rotor and the impeller to rise rapidly, making the pump shaft appear hot bending.

4) Oil is fed into the center hole of the rotor

If there is a vaporization and condensation cycle in the center hole, it will lead to asymmetric cooling or heating of the rotor, resulting in thermal bending.

5) There is friction between the rotor and the stator

The gap between the two slowly becomes smaller and then disappears, the friction causes the temperature to rise, and the pump shaft to bend due to the uneven temperature distribution of the rotor.

6) The pump shaft is not centered

The misalignment between the multistage pump shaft and the motor shaft, there will certainly be a certain slight misalignment will also lead to the obvious vibration of the pump shaft, and over time it will lead to the bending of the pump shaft, and eventually the failure of the pump shaft.

7) Variable speed operation

Torque and pump shaft speed is inversely proportional, with the deceleration of the pump, the torque of the pump shaft will also increase, making the pump shaft instantaneous burst of force greater, the pump shaft caused serious bending.

8) There may be problems with the material of the pump shaft

Uneven expansion of the pump shaft after heating will make the pump appear thermal bending, if the pump shaft in the manufacturing stage there is residual stress, such as heat release, will also cause the pump shaft thermal bending.