Reasons for high bearing temperature in multi-stage pumps
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Multi-stage centrifugal pump – manufactured by Liaoning Hengxing Pump Industry. The thrust bearing is of type 7309AC; the bearing clearance is 3 microns. After operating for half an hour, the temperature of the bearing was measured at 80 degrees using a temperature gun.
Has thermal expansion clearance been taken into account? And how is bearing play measured?
Too much lubricant can also cause high temperatures
The common reason for high bearing temperatures in multi-stage pumps is that the axial force is not properly adjusted. It’s almost certainly right. I’ve already said it – a symmetrical balance design is the best choice; it’s just a bit more expensive, but there are no other issues.
A few references: check whether the gap of the balance disc is too large; if so, use copper sheet to adjust the gap； Check whether the rear cover of the bearing housing is pressing the bearing too tightly; if so, increase the thickness of the cover gasket. Additionally, insert five copper sheets between the two bearings to increase the bearing oil clearance
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Two dial indicators, one on the left and one on the right, are placed on the vise with the bearings in between; by moving the bearings back and forth by hand, the clearance can be measured
The estimate seems to have nothing to do with the axial force. This high temperature is related to the fact that thermal expansion gaps were not taken into account. So far, only the clearance has been considered. Oh, there’s one thing I forgot to ask: does the motor use shaft bearings or ball bearings? Regarding bearing bushes, one needs to take into account the magnetic field lines, as these can also lead to high temperatures.
The bearing shells on the motor? Why are bearing shells more susceptible to the influence of magnetic field lines and thus generate heat?
The position of the magnetic flux lines determines the spacing between the couplings. If the deviation exceeds 0.5, it will subject the rotor to additional tension or compression, causing the pump bearings to be stressed in one direction. These are my humble opinions.