The main power source of the centrifugal fan is the motor. The part used to connect the fan shaft and the motor shaft is called the coupling. Generally, the coupling and both ends should be concentric with the fan and the motor, that is, the concentricity should meet the standard. The phenomenon of concentricity will cause the vibration of the centrifugal fan, and even affect the damage of the main shaft, bearings and other parts, so it is necessary to adjust the concentricity of the coupling. How to adjust the concentricity of the coupling of the centrifugal fan?
1)Measuring method of concentricity of centrifugal fan coupling
There are two main methods for measuring the concentricity of centrifugal fan couplings, one is the measurement method with a lower precision using a ruler, and the other is a measurement method with a higher precision using a dial indicator:
1. Use a ruler to measure: After connecting the centrifugal fan main shaft and the motor main shaft with a coupling, press one side of the ruler against the outer surface of the coupling in the axial direction. Without turning the coupling, measure in the order of up, down, left, and right. Adjust unevenly until the outer edges of the two coupling halves are flush. This method is relatively simple, but the accuracy is not very high.
2. Use a dial gauge to measure: Fix the dial gauge bracket on one half-coupling, and fix the measuring frame on the other half-coupling. Turn the coupling to make the two half couplings rotate synchronously, and record the readings at the four positions respectively. Then compare the values of the upper and lower, left and right symmetrical points, if the difference does not exceed the specified range, it is considered to meet the requirements, otherwise it must be adjusted.
2)The method of adjusting the concentricity of the centrifugal fan coupling
When the centrifugal fan coupling needs to be adjusted concentrically, it can also be adjusted by moving the motor. The motor usually has four feet. If the thickness of the spacer between the four feet and the base is changed equally, the motor axis can be moved up and down, and the thickness of the spacer of the front two or the back two feet can be changed, and the motor axis can be adjusted. Swing in the up and down direction; for the installation deviation in the horizontal plane, use a hydraulic jack or a copper hammer to hit the motor feet of a centrifugal fan in the horizontal direction, and the main line after the motor can swing in the horizontal plane. With a support foot, the axis of the motor can be moved in parallel in the horizontal plane.
The specific concentric adjustment operation of the centrifugal fan coupling is as follows:
1. Unscrew the four fastening bolts of the coupling guard, and remove the guard;
2. Rotate the coupling by hand to observe whether the front and rear couplings are level and whether there is any shaking or deflection; you can place a ruler and other tools close to the coupling for auxiliary reference, and observe the outer circle and straightness of the coupling during rotation. Whether the gap of the ruler has changed significantly;
3. If the coupling is not concentric, adjust accordingly:
(1) The end faces of the two pairs of wheels are parallel and the heights are equal. In this case, there is no need to increase or decrease the thickness of the gasket, just make the motor move in a plane to meet the coupling spacing, left and right radial, axial alignment requirements or quasi-rotor coupling gasket thickness.
(2) The end faces of the two couplings are parallel and uneven. In this case, it is only necessary to increase or decrease the shims of the same thickness at both ends of the rotor or at the four corners of the motor.
(3) The end faces of the two couplings are not parallel, and the upper opening is uneven. In this case, the thickness of the gasket required to eliminate the opening should be calculated according to the number of openings, and then the gasket should be added or subtracted according to the height difference.
(4) The end faces of the two couplings are not parallel, and the lower opening is uneven. In this case, it is necessary to use the number of openings to calculate the thickness of the gasket required to eliminate the opening, and then increase or decrease the gasket according to the height difference.
4. Check the end face clearance between the pump end coupling and the motor end coupling, it should not be less than 1mm, generally 2~3mm;
5. After the adjustment of the coupling is completed, replace the protective cover, and confirm that the fastening bolts of the bearing seat and the motor have been tightened.
