web handling edge guiding

Hi all,

Has anyone ever done an installation where edge guiding for coilers/re-coilers were done in a PLC, where a manufacture's sensors were used and either the a stand alone hydrualic power pack or a process's hydraulic system was used as the prime mover to a cylinder?

I know most manufactuers dont like to sell just there sensors without there controllers, but this is a system in all out lines we are looking to integrate into the plc, because of manintance and spare parts, as the systems we have right now are OLD, and parts are not made anymore for them. Has anyone dont something like this or seem anything like this?? What sensors were used, as in manufacture's names?? We arnt sure if we are going for a emitter/reciever pair just looking at the edge of the strip or a capacitance/inductance sensor looking at the total width of the strip or a camera system..I hope someone understands what I just described, and I will put a sketch together and add it to this post..

Thanks for any suggestions in advance..

Andrew

Here's a link to the picture, sorry I had trouble posting the image ...

Andrew

It Worked..

It worked..ok cool..

Before choosing components to piece together a system, I would run some tests on the existing system. I'd connect a chart recorder to the existing edge sensor and to the command output to the servovalve. Then introduce a step change to the system and monitor the reaction.

With that data, you'll have an idea of the performance that you need to meet or beat with your new system, and whether or not the PLC-based control can do it.

I've used an analog photodetector successfully. The output of the detector was proportional to the amount of the detector that was covered by the web (paper in my case). The detector itself was about an inch wide, so it was mounted so that it could be adjusted in the cross-machine direction to be able to control webs of different widths.

One other thing we found to be necessary was to run a pneumatic hose to the detector and blow a puff of compressed air at it periodically to blow off any dust that might accumulate.

Looking at your diagram, I'm not sure if yours is an edge guide system to maintain a web in position or whether it's a traversing rewind for steel strip.

What type of material are you sensing?? If it's opaque, a lot of optical type sensors could be used to sense position. If it's transparent, like plastic film, you'll probably be limited to ultrasonic or vision, and your choices will be many fewer.

We wanted to do a similar thing on a film unwind with traversing unwind stand--while replacing the old hydraulic/air system with a electronis sensor and ballscrew/motor. We wanted to use these wide range (11.25 inch) ultrasonic sensors from Accuweb (one sensor on each side--to center guide). By the time we buy the sensors and the amps to make them work, then buy somebody elses drive/motor/screw, it's cheaper (and easier) to buy the whole system, motor and all, from Accuweb.

The up side is: Their controller accepts digital and analog inputs so my PLC can command modes and the control point remotely--so our host control system will somewhat have control of the edge guide.

We install in Feb.

I like what John said. If you are not doing anything unusual Fife and Accuweb have done all the work you. Figure out what kind of control you want to do with the PLC and speak to distributor it might save you from reinventing the wheel.

I like what John said. If you are not doing anything unusual Fife and Accuweb have done all the work you. Figure out what kind of control you want to do with the PLC and speak to distributor it might save you from reinventing the wheel.

Andrew,

I know your looking at making your own- but look at this
company too-
http://www.erhardt-leimer.com/e/index.html