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Increasing the kiln speed?


We wish to modify the kiln speed from 4.3 to 6.1 rpm. What mechanical problems may be appear in (girth gear, tyers, bearings and thrust) etc.?

Apart from the obvious, needing a larger drive motor and gearbox, is the gear large enough (sufficient face width) to deliver an added 50% power? Please inspect the support roller oiling system. If it is a standard Ferris wheel with buckets, the bucket angle will have to change in the very least. Calculations may have to be made on the pour rate to make sure that such an oiling system can even work at such high speeds. Applying a forced lubrication system may be necessary. Drive vibrations often develop with speed. This will be related to torsional harmonics in the drive train. A torsional vibration analysis will have to be done on the complete drive train, motor shaft, high speed coupling, reducer shafts, slow speed coupling and pinion shaft, to see if such a potential problem exists. The OEM made such an analysis when the kiln was first designed. They should now review this in consideration of a 50% speed increase. Other factors namely alignment and ovality will become critical. Basically long term mechanical service life will be reduced and fatigue failures can be expected much sooner. Fatigue life is inversely proportional to speed. Increasing speed by 50% reduces fatigue life by 50% - unless the kiln was originally built to run at the higher speed.



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