Centre winder drive

[Puddle]

I've never done this before but it seems like something that will have been done a thousand times in the past.
Centre winder is currently manually controlled, rolls are all over the place. Winder is being used to re-roll web at the end of a production line.

Components:
-S7-1510 CPU
-Siemens G120c
-Keyence LR-TB5000 (Distance laser with analog out)
-Re SPA. T-one (load cell converter with 0-10v output)

I'm thinking I'll get a good result by using a calculation of line speed and roll diameter to get the speed to match, then use the load cell feedback to limit torque.

Potential problems that I can see:
-Getting the calculations wrong
-Response speed. G120c has a single AI connection, which will be the laser. Load cell will be connected to the PLC, filtered through a PID block and then sent to the drive via profinet.
-I'll never ever get it right and I need encoder feedback for full torque control, which the G120c hasn't got.

Drive experts, please let me know if there's anything I've missed. I've been reading up on tension control and the re-wind calculations don't look too complex.

 

[widelto]

See attached files

I did something like this in the past.
The control is done taking into account diameter versus linear speed on the recoiler.

 

[OkiePC]

I've done these before even without anything measuring the roll diameter by using a supply loop dancer or tension feedback to drive a PID block that acts as a "ratio detector". You have a limit range of ratios your winder rolls can be relative to the line speed, so once your logic adjusts to match line speed, it should follow along quite nicely. Having a diameter sensor should give you a head start, but you likely still need something to fine tune it and account for sensor imprecision. If your controller "knows" when a new roll is started, you can initialize the ratio to a known or estimated maximum (or minimum core size).

The machines I dealt with could occasionally restart from a partial roll and the controls to insert new cores and eject full rolls was all manual pneumatics with no PLC feedback, so I had to strictly rely on the slack loop or tensioner upstream of the winder and it still worked much better than the oversimplified PID it replaced. The code I replaced didn't take line speed into account at all, it just reacted to line speed changes after the slack loop or tension experienced an upset. Using line speed as the basis and the PID just to trim it made a massive improvement in quality and productivity.

 

[Puddle]

I did something like this in the past.
The control is done taking into account diameter versus linear speed on the recoiler.

This is pretty much what I've been reading and how I intend to approach it.

I've done these before even without anything measuring the roll diameter by using a supply loop dancer or tension feedback to drive a PID block that acts as a "ratio detector".

I think I'll end up running the roll slightly faster than the production, then using the tension feedback to limit it, which should result in the system being able to control the tension of the roll. The diameter seems to be required for the calculation to convert linear speed to the surface speed of the roll though.

 

[JRW]

I’ve used parts of this
Works great

https://support.industry.siemens.com/cs/de/en/view/58565043

 

[Puddle]

I think that's exactly what I need!

I found something like that before but it was designed for the S120 drives and needed some motion control licence which I couldn't even find a supplier for.

 

[drbitboy]

The diameter seems to be required for the calculation to convert linear[???] speed to the surface speed of the roll though.

How is linear speed different going to be any different from the surface speed of the roll (other than tensioner/dancer noise between the linear speed measurement and the roll)?

Roll diameter is proportional to the square root of the accumulated length on the roll, to first order (R=0.99+). Adding a phantom length to the measured length, to account for the core improves the model; material thickness is a scaling factor, but a typical value might be good enough.

 

[JRW]

That was DCC or drive control charts
It works great on s120 but it doesn’t work for g120 drives

I’m curious
What is the material you’re winding?
Motor HP or Kw?
Max roll diameter ?

 

[Puddle]

How is linear speed different going to be any different from the surface speed of the roll

I meant linear speed to rotational speed, I was just thinking about it as surface speed as I was writing it.

That was DCC or drive control charts
It works great on s120 but it doesn’t work for g120 drives

Yes that's what I was looking at. I couldn't find much information on it at all really. Maybe if I was doing this sort of thing every day it would be a necessity but I'm not there yet!

I’m curious
What is the material you’re winding?
Motor HP or Kw?
Max roll diameter ?

It's carpet, so relatively elastic and forgiving compared to some materials.
Motor is 1410rpm / 0.75kW with a 126.76 ratio gearbox
Largest roll is 4.3m, but I'll have to verify that as from a spreadsheet that I made quite a while ago.

 

[drbitboy]

I've never done this before but it seems like something that will have been done a thousand times in the past. ...

FYI:

https://shareok.org/handle/11244/320247

https://www.convertingguide.com/2020/01/24/osu-web-handling-research-center-closes-down/​

 

[widelto]

+Drbitboy: good info, I save it into my knowledge data base.

 

[L D[AR2P#0.0]]

Motor is 1410rpm / 0.75kW with a 126.76 ratio gearbox
Largest roll is 4.3m, but I'll have to verify that as from a spreadsheet that I made quite a while ago.

Confirming that is a 4.3m diameter roll of carpet?

 

[kekrahulik]

I didn't read all of the responses - so forgive me if redundant.

Control is always best if target speeds are closely calculated and then feedback is used for minor trim. So you want to calculate the proper winder speed and use loadcell or dancer feedback to trim (no more than a few percent).

A diameter sensor is good to determine a starting diameter, but it is not the best for control (you will need to rely more on the feedback if you do so). If its a winder, then you probably know the initial diameter if its on an empty core. Diameter sensor is useful for loading a partially wrapped roll.

Roll diameter can be dynamically calculated if you know the speed of the web (ie the speed of a pull roll) and the RPM of the winder. By calculating, you get the true diameter that the winder needs to run.

If you do this right, you will see that your trim (from loadcell or dancer) will be very small and will pretty much just be compensating for out of round and other imperfections

 

[Puddle]

Confirming that is a 4.3m diameter roll of carpet?

Having checked some readings, it's more like 2.5m diameter if it is run to spec. Depending on the product (thickness varies) that's about 700m linear. I think I originally said 4.3m as that's the theoretical maximum based on dimensions.

I didn't read all of the responses - so forgive me if redundant.

Control is always best if target speeds are closely calculated and then feedback is used for minor trim. So you want to calculate the proper winder speed and use loadcell or dancer feedback to trim (no more than a few percent).

A diameter sensor is good to determine a starting diameter, but it is not the best for control (you will need to rely more on the feedback if you do so). If its a winder, then you probably know the initial diameter if its on an empty core. Diameter sensor is useful for loading a partially wrapped roll.

Roll diameter can be dynamically calculated if you know the speed of the web (ie the speed of a pull roll) and the RPM of the winder. By calculating, you get the true diameter that the winder needs to run.

If you do this right, you will see that your trim (from loadcell or dancer) will be very small and will pretty much just be compensating for out of round and other imperfections

I have line speed in the control system to use in my calculation, so I should be able to get a pretty accurate figure.

My main concern was just the level of control I'll get by simply limiting the torque, or if I need to use a module drive with the CU250 and an encoder to allow full torque control.

 

[kekrahulik]

I use torque control if feedback isn't available. With loadcell feedback, you can use it to trim the speed and not mess with torque.

If you are doing this all from scratch, you may need to use some filtering on your diameter calculation to smooth it out.