Ok paper mill guys...I need some help with this one. I know there is a pressure roll talk ongoing so this is a busy day for you.

I have a wire stretch roll that is moving in the axial direction (along the roll). I have measured amplitudes at .5 ips. The roll is on air bags to adjust tension. I have suggested to adjust the tension. Does anyone know what the air bag pressure should be? I am sure it varies from machine to machine. I believe this one is set to 32 psi.

Just to follow up with what was found with this roll. Further investigation found that the Wire Stretch roll was actually moving at the speed of the Forming Roll. This was very close to 1/2X speed of the Wire Stretch roll. So...we had a resonance but why??? We watched the roll until they decided to shutdown this week. The roll got up to 1.6 ips. The only thing that was changed was the drive shaft of the Forming Roll. Axial vibration is now .1 ips. Very interesting how a drive shaft can effect another roll. One for the memory bank.

I was somewhere in your region a number of years ago for Voith Sulzer in a paper plant ~1880 making paper from wheat way back when but the paper plant is still going or was a few years ago.

Wouldn't by chance be where you are is it?

WOW...I don't know if I want to talk with you if you were here in 1880!!!

The mill I am at has been in operation since the early 90's, only 1 PM to start.

You may be talking about a plant in Henderson, KY. I am more towards Owensboro, KY (contract).

The wire stretch roll I have been talking about was from a different mill that I have been helping at, not my home base.

Jacob,

Do you know Gary McDaris in Henderson?

Danny

Sam really is that old

Sam,

When you get back in Florida, give me a call. In training now, but maybe we can get together in the afternoon.

Gary B

jschlottman,
What were you seeing in the jack shaft and drive motor? I have something similar going on right now....hmmmmm.

David Eason

David,
I have been involved in this with jschlottman so I am familiar with the progression and final fix. I am not sure what the drive side of the forming roll was doing but the tending side bearing of the forming roll had very low amplitudes until the wire stretch roll was over 1.0 in/sec in the axial direction. Radial vibration never was an issue. The tending side of the forming roll got up to .22 in/sec axially (1.4 in/sec axial on wire stretch roll) with high third and fifth harmonics. I have not seen the drive shaft yet but was told it looked like a lubrication issue with the bearings. The drive shaft was replaced and after running for approximately 24 hours the axial vibration on the wire stretch roll dropped from .14 in/sec to .07 is/sec.

Ronnie

Ronnie,
My Pressure roll had axial vibration at running speed. The roll was changed and a cocked bearing was found, but now the new roll has axial plus radial vibration of Pressure roll running speed. I can see Pressure roll speed in the Stretch, Yankee, dust collection, hand rails...but I'm not seeing anything in the jack shaft or drive motor. Based on jschlottman's find, I'm wondering if something might be there and I'm just not seeing it.

David Eason

Has anything else been changed on the machine? Paper grade, speed, wire tension, air and bag resonance are just a few of the things I’d be looking at. Air bags with proportional valve can also cause roll misalignment if the air pressure is not equalized properly. This will cause the wire to jerk across the misaligned roll in the axial direction. This can show up in the stretch roll. Often stretch rolls are hung on long arms, which make them easier to move in the axial directing. Sometimes production will try strange things involving roll loading trying to improve their drying profile and you’ll never catch it. They’ll go down for the jackshaft, via maintenance cost instead of production, clean there head box while they’re down and reset the roll tension. You’ll be left scratching your head wondering how changing a jackshaft in the press corrected the wire turning roll problem. Something got this thing going and that means it could return if the source has not be located. 1.6 in/sec in the axial would be very noticeable. Strange thing about paper machine is that what you notice often is just the result. Finding the source is often the challenge. I’d do some bumping around so see if I could locate possible resonance of interest. Has your machine been sped up beyond its original design? You’ll often see several things start to pop up when that has been done. Sometimes it takes a while for things to build up. The vibration will build slowly over time. The machine might be running great after a shut down, but a few hours later you have something like you have described on your hands. I once had a nipped set of rolls that would rattle your teeth after running 2600fpm for a couple of hours. Stop the rolls for twenty minutes to look for cover issues only to find nothing. Start-up and everything would be fine. Two hours later the same vibration would return. As it turned out cover heating was the issue. It just took a while for the heat to build up. Someone had accidentally kicked the cooling water valve handle, which restricted the flow. Again, the roll vibration was a result not the source of the problem.
Good luck and I hope you've fixed your problem.

David, I do not miss paper machines, but they can be fun to work on.