Dancer Speed follower circuit before i build one

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Do you recall the vacuum columns on the old reel-to-reel computer tape
drives? Constant negative pressure in the column maintained constant
tape tension no matter which reel held the most tape, and photocells
sensed the loop positions, adjusting the servoed speed of the reel motors.

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]

Paul M <PaulMatWiredogdotcom> wrote in

I am working now on designing a new type of tensioning system for a
machine that wraps a material under tension onto a spool using a regen
drive system. In this situation I am looking for obtaining consistent
high tension values. I believe that this will work better than the
systems out there now. It's ironic that I would be working on
designing a drive tension system and make the statement that they
don't work well, but it really depends on the product properties. The
paper industry needs either a follower system with no tension or it is
tensioning a product with little to no stretch.

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.


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Anthony

You can't 'idiot proof' anything....every time you try, they just make
better idiots.

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