Dancer Speed follower circuit before i build one

Jamie · 2006-12-06T03:25:53+00:00

This is the scenario: Lets say we have a catenary arm with a poton it that monitors the catenary position. This arm has a chive (roller) where we wrap wire aroundit to serve as a pully. As the wire starts to be pulledaway from the machine, this arm will move thus moving thePOT which signals the drive to give the reel of wire apush to maintain the catenary arm in a desired position. Now, we use regen drives for this application (Penta KB series)to be exact, and here is the problem.. The load on the shaft is heavy and what happens is when thecatenary arm moves in position to signal the drive, there may bea delay of response due to the extra swing load of weight andthus the arm might end up in a position where high bias voltage isnow at its point and when the shaft finally gets going in the other direction, it goes to fast! And thus, this extra weight generatesa lot of it's own momentum. (Swing load). This is what i want to know before i go and build it. cause ifit's on the market i would rather buy it. I need to detect the speed of which the catenary arm is moving, not the reel speed! I do not want to employ encoders on the shaftbecause of expense reasons. It must generate a negative response to what the POT wants thedrive to do as the POT starts to change position and as soon as the potstops, the POT's real signal will be reported at the position it iscurrently in. I need this type of control to not allow the drive to accelerate sofast that the catenary arm whiplashes. My thoughts on this for ideal thinking, is something like a voltagefollower that mirrors the POT's signal, a capacitive system will createan inhibiting signal as the voltage changes but not inhibit when thevoltage from the POT is stable or changing very slowly. The end results is, the POT's signal to the drive will change slowly to get the catenary arm into position but not too slow where it willcause it to stall in position. Lead, Lags, Delays etc found on mostDancer and drive...

Dec 06, 2006 21 Replies

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nospam 19 years ago

I do, IBM ones, although I think the ones I saw had a line of holes in the tape column and sensed the tape loop position by looking at which (or perhaps how many) holes saw vacuum. The real advantage of this 'dancer' system is its effectively zero weight.

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Anthony 19 years ago

Paul M wrote in news: snipped-for-privacy@4ax.com:

Actually there can be considerable stretch, even intermittent growth or shrink due to heat/cool cylcing as the material gets printed, dried and printed again going through the press. Even in the paper industry, there many printers, etc that run plastic as well as paper, on the same machines and many plastics stretch like heck. You can't have a loose web while printing, it will walk all over the place. You can't re-roll a loose web either....well....not on a 3000 lb roll anyway. It's done with a dancer and servo system. Check out the Bobst Registron systems.

Anthony You can\'t \'idiot proof\' anything....every time you try, they just make better idiots. Remove sp to reply via email

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