What Are The Methods For Checking The Pump Shaft Of A Centrifugal Pump During Operation?

Feb 04, 2025

During the operation of a centrifugal pump, if there is vibration, impact, or sudden increase in torque, it will cause the shaft of the pipeline centrifugal pump to bend or break. For certain dimensions on the pump shaft (such as the neck dimensions at the mating points with the impeller, rolling bearings, and coupling), a micrometer should be used to measure the dimensional accuracy.
2. The straightness deviation of the pump shaft of the centrifugal pump should also be measured in order to obtain the correct data on the straightness deviation of the pump shaft. Firstly, place the pump shaft between the two tips of the lathe, set two dial gauges at appropriate positions on the pump shaft, divide the outer circumference of the shaft neck into four equal parts, and mark them respectively as 1, 2, 3, and 4 points. Slowly rotate the pump shaft by hand, record the readings of the dial gauge at the four points in the table, and then calculate the straightness deviation of the pump shaft.
The calculation method for straightness deviation value is: half of the difference between the readings of the dial indicators at two relative measuring points in the diameter direction. The straightness deviation in the 0 ° and 180 ° directions of measuring point I is (0.36-0.20)/2=0.08mm. The deviation of the straight line in the 90 ° and 270 ° directions is (0.28-0.27)/2=0.05mm. By selecting a certain proportion on the graph using these values, the bending amount and direction of the maximum bending point on the pump shaft can be approximately observed using graphical methods.
4. Check the key connections. The two ends of the pump shaft are respectively matched with the impeller and the coupling. The two sides of the flat key should achieve a small interference fit with the side of the keyway on the chestnut shaft, while the two sides of the impeller hole key groove and the coupling hole key groove should have a transitional fit. During inspection, a vernier caliper or micrometer can be used for dimension measurement. If there is a gap between the width of the flat key and the width of the keyway on the shaft, regardless of the gap value, it can be determined that the flat key has lost its value of use. Therefore, the keys should be re filed and leveled according to the actual width of the keyway and the fitting tolerance. The two sides of the keyway should be perpendicular to the bottom surface of the keyway. If there is any tilting or unevenness, it should be repaired in a timely manner.