unwind drive

Good Morning.
I will be designing a unwind station to provide material to a nip roll that runs at a constant speed once dialed in by the operator. There will be no rewind. The material is fairly prone to mechanical distortion.
I am hoping that I can find a servo controller or a VFD that has a predefined unwind function built in.

Do any of you guys have any suggestions?
Thanks

Joe
Here you go
https://support.industry.siemens.com/cs/document/38043750/sinamics-s%3A-dcc-winder?dti=0&lc=en-US

Winders/Unwinders are pretty complicated. You may need some help

Consider if you need a driven unwind or a braked unwind.
What kind of tensions are you looking to maintain?

SEWs MovidriveB series has a build in application for winding/unwinding.

http://seweurodrive.com/produkt/constant-tension-center-winder.htm
http://download.sew-eurodrive.com/download/pdf/11341114.pdf

I used it once for a small strip cutter, but the material wasn't that fragile (1200kg rubber ply). It held the programmed tension pretty well, considering that it had to fight the worn out (well driven in...) mechanic installation...

Ps: Forgot to mention it, there was no tension or diameter feedback, the diameter is calculated over running time and a min/max roll diameter parameter, friction coefficients are measured during the initial setup. Both parameters are then used to calculate the resulting tension. If you will have different max roll diameters you should use a diameter sensor with it.

I think I would need a driven unwind.
If anything I would like just a little slack between the center winder and the unwind

Help me out a little bit here. First you say:

Originally posted by JoeM1:

I will be designing a unwind station to provide material to a nip roll that runs at a constant speed once dialed in by the operator. There will be no rewind.

Click to expand...

But then you say:

Originally posted by JoeM1:

If anything I would like just a little slack between the center winder and the unwind

Click to expand...

So is it unwind/pull roll or unwind/rewind?

How fast is this supposed to run? How much total tension will this operate with (one man's "fairly prone to distortion" is another man's "holy ****, I can't hardly break this stuff!!)? What is the roll diameter range (min to max)? I assume this is a center driven unwind but please confirm that.

If you want to run with any slack then you are in the realm of droop control. You would use a sensor to measure the height of the web in a span between rolls and modify the speed of the unwind to maintain that height. This works right up until the web is pulled tight (minus a little margin). It really works similarly to a somewhat nonlinear version of dancer control.

If you want to run with a specific tension value then you are into open or closed loop torque control or closed loop velocity control. It all depends on what you need to accomplish and what the operational parameters are.

Keith

Well I cant get into too much detail, IP being what it is and all. Droop control is probably the method moving forward, thanks for the links to the drive manufacturers.