Count unwinding wire

What are you manufacturing? Transformers, clamps?

If the reel is on a spool you could count revolutions.

A very simple method is to count the products made and multiply by the standard length/weight per part.

Sorry my bad, I did not read your question.

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There are several assumptions here. First, I think you must be saying that you do not know how many feet of wire are on a spool? If you install a rotation counter on the source spool, you will quickly find an average number of feet per spool, and then be able to produce a number which represents the average minimum number of rotations per spool to approach emptiness.

If the number of feet on a spool is not consistent, then a linear wire counter (by the foot) will not help you. Ideally, each spool would have a marker located on the wire of the source spool, which would indicate eg 50 feet from empty, so you could stop your machine in a timely manner. (I assume this is why you want to know?)

If you are driving the source spool with a motor, then perhaps you could install a load sensor(current draw) in the motor control circuit. Measure the amount of current draw required to turn an empty spool, and then of course, you can calculate the approximate amount of current drawn when any spool is nearly complete. If your motor controls are run by PLC, then you will be able to program the motor to stop within reasonable time, based on an analog load setpoint.

Another wild idea, is to use a weight scale under each spool, and to have measured the weight of the empty spool (assuming they are of consistent weights) and then you will know when you can implement PLC controls as mentioned above, to stop based on analog setpoint.

I may be able to help more if I know more about your process and products. I have built equipment in the past for winding transformers. They were cheap, and while the system did have a rotation counter on the destination winder, the spools of copper wire were very consistent in the number of turns of wire they had on them, and typically would all run empty at nearly the same time, so the operators could look at a spool and tell if there was enough wire to run another batch.

I'm curious to know more.

Rather than a counter, which doesn't measure feet supplied due to the coil size reducing as the wire is unwound.

Why not just measure the revolution of the supply roller or whatever you have pulling the wire off the spool? At least that roller or pulley will have a constant diameter allowing revolutions to be linked to feet length etc...

As for the type of counter there are so many that would do the job, depending on speed etc... a simple mechanical counter may suffice.

John.

There are several ways they do this in the field and most often they rely on 2 or 3 together as there is so much that can give you the wrong reading.

Slippage will render the revolutions of the drive wheel useless.

Spool revolutions only work if there is one layer on the coil.

In wire eroding we used to count revolutions on the drive wheel, have a sensor arm lay on the spool coil surface linked to a micro switch to trigger an alarm when it 's diameter falls below a certain level and on top of all that we would have a tension measuring device which was self made. It was two pins, perpendicular to the wire direction, with the wire running between them. The 2 pins were connected to a micro switch each, the top pin having it above and the bottom pin below.

Depending on the angle of the wire you would slightly tense the pin that holds the wire from becoming taut and set the micro switch so that if the wire gets snagged it pulls on the pin and so setting of the alarm.

The same with the bottom pin but that has to be very sensitive as it detects lag in the wire.

The whole thing had a brake on the spool and was set up delicately to work as a system. Not one item did a job on its own, it only worked when all was right together.

Hope it helps.

For about a hundred bucks and up you can get various types of IR beam devices that operate on 12-24 VAC or DC. They are popular in security. More robust units are generally used for industrial automation, but require outboard relays and controllers.

You get two boxes and provide power each of them. Position the units so the (beam) will connect when the wire is nearly out.

The internal relay can be used for a signal or to stop the operation.

Weigh one foot of wire and do the math

You're making this WAY more difficult than needed.

Set the wire spool carrier onto a scale - when the scale reaches a given weight, it's time to watch the reel.

You haven't told us what kind of wire or size, and in a given manufacturing process, adding a 'counter' would add drag to the wire, therefor a possibility of feeding issues.

Don't raise the bridge; lower the river!

Still too difficult, your relying on a operator to sit there and watch the reel between the lowest point and empty, the machine could be a fully automatic machine, or semi automatic machine, and your distracting the operator with a menial task of watching the feed spool.

Get a meterage/footage roller and place a idler arm on the feed spool or on the wire itself, and count the distance of wire coming from the spool, very simple with minimal components, and being wire, you'd be buying it as a known length, not just by weight, so the reels could be 500' or 10,000' reels or more (depending on the wire guage)

Get a PLC or computer to monitor the footage as the reel unspools, and activate a indicator to let the people who change the spools enough time to ready up the new spool to minimise the changeover time.

Using the idea to sense the end of the wire, while will work, your not saving time, as the end of the wire is reached, then you have to contact the people in charge of supply, organise for the new spool to be setup, and all this could be done minutes or hours before the spool is exhausted.

The end of wire detection can then be utilised for a marker that stops the wire in a particular position if the wire is then end bonded to the new spool of wire.

I work for PFERD Milwaukee Brush Co. We are a company who manufacture steel wire brushes for welding aplications. THe way we know when to change our wire spools is very simple. Have a a frame with a ring near the spool. The wire goes through the ring and then through another ring that is welded to a metal bike chain. The ring that is attached to the bike chain is suspended above a ground out plate. The idea is this, once the wire of the spool runs out, before the last end of the wire goes into your machine, the ring that is welded onto the bike chain comes down and rests on the ground out plate. The machine grounds out, stopping the operation. This has worked for spools that range from 40-60 pounds where tension would be of higher concern.

Ron Terrell,

terrellr@msoe.edu

If you want to know the length of wire on spool, even before loading on the machine, it is simple:

The weight of copper (or whatever is the material) is marked on the spool. You also know the gauge of wire. You can find out length of wire per Kg (or pound) from wire data (easily available on net also) for your gauge of wire. So length of wire on spool is

Length of wire per Kg (or pound) X total weight of the wire on spool (in appropriate unit)

This will be accurate enough.

I apologize if this was already stated, but you could use a laser displacement sensor to measure the height of the wire wrapped around the spool. As the wire unravels, the height on the spool decreases and the measurement from the sensor will increase (since the wire will be getting further away. All you need to know is the measurement value that would constitute as "nearing empty" and you'll be all set. They make these sensors in many different forms and will certainly have a variation suitable for your operation.

If you've ever gone to WalMart, or K-Mart or various other department stores to buy wire, you will note that they have rolls of wire that they simply feed the end through and it goes between two steel rollers. These rollers are held rather tightly together against the wire. As the wire pulls through the rollers, it causes them to turn. A dial is caused to turn in unison with the rollers and indicates the length of the wire as it exits the rollers.

This is simple enough. The rollers could be monitored by a device that would send a signal to a more sophisticated receiver and display the results on a LED or LCD screen, or any number of other devices. This set of rollers could be placed four feet, for example, from the place where the wire exits its spool. A simple photo cell could sense when the end of the wire has been reached and cause the device pulling the wire to stop or whatever other action the application requires.