Wrapping machine retrofit

Hello
We are considering retrofitting our wrapping machine, a Signode Sprialgrip 500, with modern, non proprietary controls.

The only hangup is this machine has the most overly complex tension setup we've seen.

There are two strain gauges working on some form of propietary board. This board acts upon a cheap DC drive to pulse a motor on and off, which in turn spins this Rube Goldbergian contrivance which unreels the shrink wrap.

What can I do to simply this mess? It is very prone to failure and has not worked very satisfactorily in the last 3 years. I dont want any proprietary components.

Mechanical means are an option, we have a fairly good machineshop down the street that could fab some new rolls or something.

Any notions?

You have not provided much to go on. Operating speed is an important factor in the control of an overwrap machine. Jaw motion profile, and yes film tension. If the machine is running at 35 PPM and using a heat tunnel you will need a completely differnet approach then a machine running at 1000 PPM fin sealed flow wrapper. More info would help.

God your asking for the earth here. I don't know the mechanics of it by I have worked with and around Kisters on quite a few occasions and always been awestruck by the size and complexity of their tensioning systems.

To ask someone for design tips on something as complex is this is I would believe is beyond this forum.

I would look for specialists who could modify the equipment for you, I know of one in the UK that take in overhaul and modify second hand Kisters, that is the sort of company you would want.

http://www.wulftec.com/retrofits.html

Two of our stretch wraps were retrofitted with these. The tension mechanism is so simple - two different size motor-driven rollers, the film is prestretched as it comes off the head. Speed control is through an analog prox driving a VSD driving the motor. A little bit of wiring to get it up but then troublefree.

Doug-P said:

http://www.wulftec.com/retrofits.html

Two of our stretch wraps were retrofitted with these. The tension mechanism is so simple - two different size motor-driven rollers, the film is prestretched as it comes off the head. Speed control is through an analog prox driving a VSD driving the motor. A little bit of wiring to get it up but then troublefree.

Click to expand...

We are talking about a pallet wrapper, right? I have done a few and as Doug mentioned the tension can be done using 2 rollers for the feed and one spring loaded tension roller that has a cam on it for an analog prox. Note: it can be done without the analog prox but boy do those things make it easier.

I have always used DC drives and gearmotors for the film wrap and lift but the turntable can be AC motor with gearboxes on contactors. You normally have to be able to slightly open the 2 drive rollers when installing a new roll of film so a release arm is needed that will tension the chain when latched close. I prefer chains to belts because of the constant releasing and re-tightening. In this case chains are best for turn, lift, and film feed.

I did not realize there was that much engineering required for the tensioning.