Linear Position Transducer

Aefyn · Mar 12, 2015

I was looking at http://www.zettlex.com/shop/lintran-400/

I need to know the position of a metal block attached to a roller that rides slowly up and down a 3' threaded rod. If I know the position of that block I can get the roller positioned perfectly between size changes. The rod is 3' but the rollers only ever move 12-16" on that 3' rod.

Anyone else have some suggestions about who or where I can get something like this or that would give me a position? I didn't want to put in a pot as the rod can turn over one hundred times. An encoder seems like overkill and I believe I would need more cards in my AB 5/04. With a 0-10V signal I could just use the existing analog input card and be done. The motor moving this is a Slo-Syn SS700 from Superior Electric and I don't see any way to get position off of it.

I liked this solution because it was a magnet with no moving/touching parts rather then a rod that may get worn. I am in the printing industry so anything here will get covered in grease, oil, ink, and grime pretty quickly.

Anyone have any thoughts on this? Better sensor type or company? Better for industrial? I'm trying to stay around $500 per sensor.

RonJohn · Mar 12, 2015

In the past, I've used Balluff and Temposonics linear transducers. Not sure about where Temposonics is located, but Balluff has a US HQ in Kentucky. Lots of standard parts with quick turnaround.

adisharr · Mar 12, 2015

Aefyn said:
I was looking at http://www.zettlex.com/shop/lintran-400/

I need to know the position of a metal block attached to a roller that rides slowly up and down a 3' threaded rod. If I know the position of that block I can get the roller positioned perfectly between size changes. The rod is 3' but the rollers only ever move 12-16" on that 3' rod.

Anyone else have some suggestions about who or where I can get something like this or that would give me a position? I didn't want to put in a pot as the rod can turn over one hundred times. An encoder seems like overkill and I believe I would need more cards in my AB 5/04. With a 0-10V signal I could just use the existing analog input card and be done. The motor moving this is a Slo-Syn SS700 from Superior Electric and I don't see any way to get position off of it.

I liked this solution because it was a magnet with no moving/touching parts rather then a rod that may get worn. I am in the printing industry so anything here will get covered in grease, oil, ink, and grime pretty quickly.

Anyone have any thoughts on this? Better sensor type or company? Better for industrial? I'm trying to stay around $500 per sensor.

MTS Temposonics, Balluff and Ametek also make similar devices to the Zettlex unit.

The Gemco (Ametek) part# 955LC-VO-0070 7.0" stroke analog 0-10V out model is about $ 400.00 (Repeatable to 0.01%)

You can order them in 0.1" stroke increments.

Aefyn · Mar 12, 2015

Thanks,

I found one from mts.

http://www.mtssensors.com/fileadmin/media/pdfs/E_Series_EP2_Analog.pdf

This should work well for my application and it can be here in 2 weeks. Thanks for being the best forum on the web for automation!

rocksalt · Mar 12, 2015

What is the amount of position error you can have in order to satisfy the process? A simple solution that is cost effective could be a string pot or maybe even a ultrasonic sensor depending on the location. Unimeasure has products (string pots) or IFM and Keyence. Also..

What will be tricky is to be able to position the object, especially in closed loop.

Plastic · Mar 12, 2015

rocksalt said:
What is the amount of position error you can have in order to satisfy the process? A simple solution that is cost effective could be a string pot or maybe even a ultrasonic sensor depending on the location. Unimeasure has products (string pots) or IFM and Keyence. Also..

What will be tricky is to be able to position the object, especially in closed loop.

Yep, this is a rapidly deployed and economical solution.
"String-Pot" is the term for Cable Extension Transducer. Cable pays out with the moving axis, and is retracted into a rotary device via spring tension. These devices tolerate side shift, floating alignment issues.

Although the original string-pots were literally potentiometers, subject to reduced lifetimes, the same product is now available in OPTICAL equivalent to give analog output or encoder output.

They come in all shapes, sizes, and prices. Google Celesco Cable extension transducer.

rguimond · Mar 13, 2015

How about a laser distance sensor? We use these:

http://www.bannerengineering.com/en-US/products/sub/680

Aabeck · Mar 13, 2015

I worked on a Minster feedline for an automatic press & the coil reel travelled over 6 feet - for the position they had a cable pull tranducer that pulled the cable out & sprung retracted as it travelled. The actual tranducer assy wasn't that big. I remember it didn't have any name or markings on it (Minster considers a lot of the parts they use Proprietary & wan'ts you to buy them from only them) But it should be a commercially available item. And this one was optical to the SLC blue-hose, not a pot.

It was very accurate & the only problem they ever had was a material handler hit the cable with a lit OxyAcet torch.

Str8jCkt · Mar 13, 2015

Have used several from Turck.
you can get them in various packages, sizes and fieldbus comms besides the standard analog.

http://pdb.turck.de/media/_es/Anlagen/d101791.pdf

Aefyn · Mar 13, 2015

Honestly if I'm within 1/2" they will be happy. Within 1/4" and the automatic scanner will pull it in. This is a process with a camera, an encoder, and this Slo-Syn motor that moves the compensator.

If you've ever seen the color bar on a box of cereal, it's lining up each of those colors. If it's outside 1/4" they have to move it manually until the camera can see it and pull it in. I think with this solution it will pull it in and then I'll hand it off to the automatic mode to keep it running.

They do about 5,000 changes a month and takes them a minute to pull it in manually. The scanner and other items are older and not able to pull the dots when they are more then +/- 1/4".

http://www.westcoastplastics.com/HTML/MTS-EP2-Analog.pdf

Is what I got and it seems to be great, magnet so the dust won't matter and the resolution is way over for what I need.

jraef · Mar 13, 2015

So if you already have an encoder, why not just count the pulses to the desired destination?

Aefyn · Mar 13, 2015

Sorry didn't give the full picture. There is paper going over the roller. I know the speed of the paper going through the press. I don't know the speed of the roller moving up and down to move the cutoff.

CapinWinky · Mar 13, 2015

An encoder is overkill but a linear measuring device is not? An encoder is cheaper and an encoder card should be cheaper than an analog card.

Anyway, I would do a poor man's encoder, put a bolt on the shaft that you can see with a prox and count revolutions. Need more resolution? put a star wheel looking thing on the rod to get more pulses per rev. Cost is whatever a cheap prox is and your time, the bolt is negligible.

EDIT: You may need a second prox to home against in case you lose the position.

Aefyn · Mar 16, 2015

I found 6 pots that are going to an analog card in the system. Of these pots 4 haven't been used in years, the other 2 are only used to take a master 0-10V signal to 0VDC and 10VFC when calibrating the drives. We calibrate the voltage output of a drive using them.

Since they are hardly ever used, and even when used are only used by maintenance staff I'm moving them to a panel view. I'll make a button there that scales 0-100 and get back my 0-10.0 value.

That opens up 6 analog inputs and I only need 5.

Trying to utilize existing resources otherwise an encoder would be fine. I am also new to the automation game and wasn't sure what I would need for high speed inputs for AB. I had put some on using Direct Logic and those needed a card for each encoder unless using the single high speed inputs on a DL06.

For encoders on AB how many can fit on a single card?

Racer5039 · Mar 16, 2015

I have used these with a ML1100 to track a roller in a small cardboard machine. Work's well and don't break the bank. http://www.unimeasure.com/

Linear Position Transducer

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