Cause Analysis Of Broken Shaft Of Blower Motor

Cause Analysis Of Broken Shaft Of Blower Motor

When the blower motor is running, the dust of the impeller generates an exciting force, and the surge in a fault condition generates an additional impact load. Two major factors cause the blower motor to easily break the shaft.

1.Impeller dust problem

When the fan first started working, the vibration of the bearing part was very small, but as the running time lengthened, the dust in the fan would adhere to the impeller unevenly, gradually destroy the dynamic balance of the fan, and make the bearing vibration gradually increase. Once the vibration reaches the fan maximum value allowed, the fan must be shut down for repair.

2.Surge problem

The fan periodically blows out and reverses, and the flow is repeated periodically, causing the fan to vibrate violently. At the same time, the noise of the fan is increased. When the surge is severe, it may cause damage to equipment and bearings and cause accidents.

3.Matching problems cause the motor shaft to break

If the assembly coordination between the drive motor and the high-pressure blower is relatively good, the output shaft of the drive motor will only bear the rotational force (torque), and it will run smoothly without pulsation. When not concentric, the output shaft of the drive motor also bears the radial force from the input end of the high-pressure blower.

The action of this radial force will force the output shaft of the drive motor to bend, and the direction of bending will change continuously with the rotation of the output shaft.

If the concentricity error is large, the radial force will increase the local temperature of the motor output shaft, and its metal structure will continue to be destroyed, which will eventually cause the drive motor output shaft to break due to local fatigue. The greater the error of the concentricity between the two, the shorter the time for the output shaft of the drive motor to break.

When the output shaft of the drive motor is broken, the input end of the high-pressure portable blower will also bear the radial force from the output shaft of the drive motor. If this radial force exceeds the maximum radial load that the input end of the high-pressure blower can withstand, the input end of the high-pressure blower will be deformed or even broken or the input end support bearing will be damaged.

4.Quality defect causes the broken shaft

The sharp angle of the undercut during turning leads to stress concentration fracture! The roughness of the convex part of the fracture surface is the initial part of stress concentration and the culprit of fracture.

The possible reasons are:

1)The arc of the undercut processing is too small or has burrs and sharp corners;

2)The motor pulley has a big jump, shaking and breaking;

3)Excessive heat or hardening of the quenching and tempering treatment, and the carbide of the hot-rolled steel rod in a band or mesh shape may also cause the shaft to break.

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