Yesterday I took some readings on a slow speed cylinder roll bearing. At 760 FPM heavy impacting with crest factor levels of over 12 were recorded. Pk-Pk waveform levels were almost 2 G's. When I felt the bearing a heavy non repetitive knocking was observed. I checked the bearing again at 820 FPM and this condition disappeared. Crest Factor is 4 and Pk-Pk waveform levels are now at 0.01 G's. The spectrum shows random, broadband raised noise floor levels. I have seen this condition before and they have examined the bearing and could find nothing wrong with it. Has anyone ever had an experience like this that they could share?

Cylinder_Roll.doc (68 Kb, 34 downloads) Cyliner Roll bearing vibration

Resonance?

Check thoroughly for any looseness or cracks.

Regards
Ibrahim

Rob,

I tend to agree with Ibrahim that resonance may be an issue. I have seen transfered vibration from the fan pumps/machine screens to the individual former vat tanks that was the source found on the cylinder/couch rolls.

There may be also be axial loading issues caused by the decrease in torgue of the drive system or change in the feeding of stock to the vat allowing some axial endplay.

Give me a call to discuss this week if you get a chance.

Jim

Jim,

I think you are on to something there regarding axial loading issues caused by the decrease in torque. They have found that some of the rollers were sliding through the load zone instead of rolling at a certain speed. They have also found that the bearing housings were not centered properly and slightly cocked. Jim, I'll call you when I get a chance.