Here where I work they want me to mount a pickup on a Center Roll Doctor to give a continuous readout of the Vibration. I guess they want to monitor when it increases or decreases with speed or other things. I am considering a pickup that gives a 4-20 ma signal in relation to 0-1 inch/second. I actually have no real idea what to expect as far as amplitudes. I am planning on feeding the signal to our control loop so they can trend it against speed or whatever they want. The signal doesn't have to be 100% accurate as long as it decreases and increases where they can tell if things are better or worse.

Has anyone had any experience doing this any suggestions are helpful.

Thanks
Mike Brooks

The change is a plant modification. It should go through the review and approval process, shouldn't it?

No modifications, I am just adding a pickup and the instrumentation people are taking it from there. I don't have to have any approval for any pickups i deem necessary to add.I was just wondering if anyone has ever done this before on a doctor blade.

Thanks

Mike,

I've never done it on a doctor blade, but I would be try to make sure that 1 ips is enough. I would guess (an experienced guess, but still a guess) that you could see as much as 5 ips.

Is there any way to use a non-contact sensor?

Today sometimes I am going to try to put my walk around on it and see what the amplitude is so i will at least have some idea. No way to do a non contact probe. The pickup will actually not be in the middle but closer to the edge.It won't be a true reading of what the doctor is actually doing but it will increase or decrease if blade vibration goes up and down. Maby this will tell me the frequency it is bouncing at and if theres a certain roll speed that excites the blade, and which roll.

Mike

We also had to monitor the vibration on a doctor blade on a roll in a paper mill and the reason was they were considering going from using a blue steel doctor blade to a ceramic blade to increase the life of the blade between changes.

Mike,
Are you the Mike Brooks who worked at Temple Particle Board in Monroeville years ago. I use do go there regularly to balance their fans until they bought their on IRD 880.
Just wanted to say Hi if you are.
Also I work at the paper mill here in Mobile with David Hickman and if you are interested, I can get you the frequency ranges and amplitudes on the doctor blade they are monitoring. They are doing it through their online monitoring system so we are not directly connected to monitoring it but I do have access to their system.

Ronnie

Hi Ronnie yes its me. I would love to have the amplitudes and frequencies. THat would give me a ball park anyways. By the way you were a good teacher on the 350..Hope all is well.. thanks a lot
Mike

Mike,
Well, they took the sensor off the doctor blade and quit monitoring it. But there are four envelope readings stored that I can give you.
E1 is 300 CPM to 6KCPM filter and was .013 GS
E2 is 3KCPM to 60KCPM filter and was .015 Gs
E3 is 30KCPM to 600KCPM filter and was .03 Gs
E4 is 300KCPM to 2.4M and was .06Gs
When they first set this up I saw a 0 to 1000Hz fmax with an overall of less than .1 in/sec. and I put a hand held sensor on it and aquired a spectrum out to 5000 Hz but did not see anything above 1000 Hz. also I was told they observered .5 in/sec overall while monitoring it live in the 0 to 1000Hz range.

Good to hear from you,
Ronnie

Thanks Ronnie. I think I will use a 1/ips to 4-20 ma and see how that goes.

Mike