In industrial production, centrifugal fans are often used as induced draft fans, but after long-term operation, many centrifugal fans show axial vibration, but the vibration of other parts is within the normal range, then the axial vibration of centrifugal fans What’s the big reason?

1. Reasons for the large axial vibration of the centrifugal fan

1. There is friction between the impeller and the air inlet chamber: The impeller of the centrifugal fan usually has a certain small gap with the air inlet chamber. This gap will be maintained even during operation, but if the gap disappears, it will This leads to constant collision between the two, resulting in increased axial vibration.
2. The foundation is not firm: The weak foundation is also one of the reasons for the large axial vibration of the centrifugal fan, such as loose anchor bolts, unstable cement foundation, unstable secondary grouting, and no backfilling soil. Doing the foundation on the top, or without stretching the foundation, etc., will cause the axial vibration of the centrifugal fan to increase.
3. Bearing damage: If the centrifugal fan bearing is damaged, it will cause the impeller to run erratically, make the impeller appear axial runout, and then cause the axial vibration to increase.
4. Bending deformation of the main shaft: If the centrifugal fan runs with high load for a long time, the main shaft is clamped by internal and external stress for a long time, which may cause bending deformation, resulting in the left and right deviation of the impeller when it is running.
5. Unbalanced impeller: Before the initial use of the centrifugal fan and after using it for a while, the balance of the impeller should be corrected, and the imbalance will cause large axial vibration.

2. the solution to the large axial vibration of the centrifugal fan

1. Restoring the gap between the impeller and the air inlet chamber: There are many reasons for the reduction of the gap between the impeller and the air inlet chamber, which need to be checked gradually. If the impeller bearing is damaged, it can be replaced in time; too much dirt adheres to the surface of the impeller, which causes the load to become larger and causes the bearing to deform. It is necessary to clean the impeller and replace the bearing.
2. Reinforce the foundation of the fan: Clean the foundation surface, and insert shear-resistant steel bars along the foundation surface after chiseling. Above the concrete surface layer, 0.5m thick reinforced concrete is added, and longitudinal steel bars and circumferential steel bars are arranged inside. After that, the original backfill soil is used for layered paving, and the vibrating rolling layer is statically pressed to the design high-rise to ensure that the top surface of the foundation backfill soil is lower than the top of the foundation ring, and the surface is provided with a drainage slope.

3. Repair/replace bearings: In general, if the centrifugal fan can be repaired, try to repair it as much as possible. Replacing bearings is not only expensive, but also time-consuming and energy-consuming, but if it cannot be repaired, It is necessary to replace the bearing, because the damage of the fan bearing will not only cause the axial vibration of the fan to increase, but also be detrimental to the operation of the fan. For the specific replacement method of the centrifugal fan bearing, please contact the manufacturer’s maintenance personnel.
4. Replace the main shaft: The main shaft of the centrifugal fan is deformed and bent, and the editor strongly recommends to replace it, because even after the deformed main shaft is repaired by heat treatment, the internal structure can no longer carry more torque, It is easy to deform again, causing the centrifugal fan to fail, so when the deformation of the main shaft causes the axial vibration to increase, it should be replaced directly.
5. Correction of fan balance: The balance of centrifugal fan is an important condition to ensure the normal operation of the fan. About how to balance the centrifugal fan, I have written a related article before, which introduces the two balance methods of dynamic and static in detail. Among them, the dynamic balance correction of the working speed is simple to operate, but the precision is not high enough, and the static balance correction of the guide rail type static balancer is used more in enterprises.