Several misunderstandings in maintenance of explosion-proof centrifugal fan
1. When adjusting the coupling between motor, fluid connector and explosion-proof centrifugal fan, please do not use the following two methods for alignment.
(1) Use the auxiliary flat block and use the clearance gauge to measure the deviation in radial and axial directions.
(2) The two half couplings are not in contact and are fixed on the fixed half coupling with dial gauge, so the probe can measure the deviation in the radial direction and shaft direction of other rotating half couplings.
Reason analysis: the positioning accuracy of explosion-proof centrifugal fan coupling is very high, and it is necessary to ensure that the coaxiality in normal operation state is within 0.05mm. Due to the influence of the dirt of the coupling itself, the actual coaxiality value will usually exceed several times or 10 times, which will cause serious vibration of explosion-proof centrifugal fan. Method (1) is generally used to roughly locate C / W and places with low requirements, but it is not suitable for the positioning of explosion-proof centrifugal fan. Method (2) does not rule out the influence of shape error, but uses high-temperature fan.
The correct method: centrifugal fan uses 2~3 bolts to temporarily connect 2.5 coupling to synchronize rotation, and uses 3 (rapid alignment) or 2 scales to measure radial and axial vibration values, and then adjusts to the required conditions.
Second, the explosion-proof centrifugal fan of the coupling takes the above method as the center, and the coaxiality is also controlled within 0.05mm. However, the influence of the explosion-proof centrifugal fan, oil pressure coupling and the expansion difference between the motor and the centerline at low temperature on the high-temperature conditions is ignored. Or, even if you are careful, the operating temperature of explosion-proof centrifugal fan will be high, so you must reduce the cold centerline.
Reason analysis: when the explosion-proof centrifugal fan works normally, the temperature of the fluid joint (greater than 80 ℃) is higher than that of the motor and bearing seat (oil pump lubrication), and the corresponding thermal expansion becomes larger. Therefore, the center needs to be removed in the cold state. Lower the line a little. The high temperature environment of absolute explosion-proof centrifugal fan propeller configuration cannot be used as the basis of high thermal expansion of the computing center.
Correct method: in order to make the center line of explosion-proof centrifugal fan, fluid joint and motor in a straight line in theory under high temperature during normal operation, the center line of fluid joint is deliberately lower than that of motor. Explosion proof centrifugal fan, generally 0.1? 0.2mm。
3. When installing the bearing rear end cover, the fixed end and free end cover are not installed correctly.
Cause analysis: in order to adapt to the thermal expansion caused by the high temperature environment of the fan shaft, the manufacturer designed a non fixed bearing at the tail. The bearing must be strictly positioned during installation, and there is no limit on the expansion side of the free bearing. If installed after replacement, the free expansion and contraction of the shaft is limited, which may lead to machine accidents.
Correct method: according to the length of the bearing end cap inserted into the flange part, install the short upper half and lower half of the flange at a distance. At the same time, the positioning reliability of other end caps is ensured, and the insufficient positioning will not be caused by the thickness of the sealing ring.
