movement wire sensor

Thread Starter

eduardo2102

Joined May 6, 2021
4
Hello, I need a sensor that gives me a high signal when a wire is in motion entering to the stripping machine

I attached a photo, i hop that you can help me.

Thanks!!
 

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cmartinez

Joined Jan 17, 2007
7,332
Hello, I need a sensor that gives me a high signal when a wire is in motion entering to the stripping machine

I attached a photo, i hop that you can help me.

Thanks!!
There are many ways to go around that, you could place a small rotary encoder or a friction actuated device touching the wire. Does the machine use a PLC? Or is it semi-automatic?
 

Irving

Joined Jan 30, 2016
1,497
How much motion? Are we talking mm or microns? What gauge wire, & what material? How fast is it moving? Do you want just to know if it's in the machine or if it's reached a specific point?

You must give details of the problem if you expect a useful answer
 

Thread Starter

eduardo2102

Joined May 6, 2021
4
How much motion? Are we talking mm or microns? What gauge wire, & what material? How fast is it moving? Do you want just to know if it's in the machine or if it's reached a specific point?

You must give details of the problem if you expect a useful answer
the motion is a mmmm maybe 3mm/second. I Only need a signal when the machine is in use for remote monitoring. Gauge: from caliber 16 to 28
 

Irving

Joined Jan 30, 2016
1,497
the motion is a mmmm maybe 3mm/second. I Only need a signal when the machine is in use for remote monitoring. Gauge: from caliber 16 to 28
OK, do you need to know its speed, or just that its moving?

How does the wire get into the machine? 28 gauge is quite fine and needs a different sort of handling from 16 gauge. A pair of soft rubber pinch rollers will detect wire movement with a simple bar magnet attached to one roller and a hall-effect sensor or a simple opto-interruptor and a 3d-printed slotted disc. You need to have enough load on the wire to detect its motion but not so much that it restricts movement, stretches it or prevents it being fed into the machine. Ideally the magnet/slotted disc would be attached to an existing guide wheel/pulley that turns by virtue of the wire passing over it, so as not to complicate the wire path.

The output of the hall sensor or the opto-interruptor is a series of pulses. These need to be fed to a 555 timer wired in a monostable configuration with a time constant of, say, 0.5 - 1 second. This will give a constant high output while the wire is moving (ie magnet/slotted disc turning) falling to zero when its stationary.

The electronics is trivially easy. The mechanics could be very difficult & depends exactly on how the wire feed path is configured/managed. Without knowing more about the machine and how wire feeding is managed its hard to advise further.
 

cmartinez

Joined Jan 17, 2007
7,332
OK, do you need to know its speed, or just that its moving?

How does the wire get into the machine? 28 gauge is quite fine and needs a different sort of handling from 16 gauge. A pair of soft rubber pinch rollers will detect wire movement with a simple bar magnet attached to one roller and a hall-effect sensor or a simple opto-interruptor and a 3d-printed slotted disc. You need to have enough load on the wire to detect its motion but not so much that it restricts movement, stretches it or prevents it being fed into the machine. Ideally the magnet/slotted disc would be attached to an existing guide wheel/pulley that turns by virtue of the wire passing over it, so as not to complicate the wire path.

The output of the hall sensor or the opto-interruptor is a series of pulses. These need to be fed to a 555 timer wired in a monostable configuration with a time constant of, say, 0.5 - 1 second. This will give a constant high output while the wire is moving (ie magnet/slotted disc turning) falling to zero when its stationary.

The electronics is trivially easy. The mechanics could be very difficult & depends exactly on how the wire feed path is configured/managed. Without knowing more about the machine and how wire feeding is managed its hard to advise further.
I was going to suggest exactly what you've described. My only comment is that he could use a single pulley wheel around which the cable would loop once. Protection against disengagement due to low tension could be made by adding a well designed shield around the wheel.

The wheel in turn could have a magnet inserted in a blind orifice so that said magnet would be flush on the wheel's surface. A hall sensor would detect the magnet's presence/absence and said hall would be connected to a monostable 555 timer as you've just mentioned.
 

Irving

Joined Jan 30, 2016
1,497
My only comment is that he could use a single pulley wheel around which the cable would loop once.
You might struggle with the larger wire gauges unless its a fairly large diameter pulley. Also looping the wire round puts a twist on it that might not be desirable.

Of course, it just occured to me that if the wire is being pulled off a reel then the obvious place to fit the sensor would be the reel's axle!
 

cmartinez

Joined Jan 17, 2007
7,332
Of course, it just occured to me that if the wire is being pulled off a reel then the obvious place to fit the sensor would be the reel's axle!
You're absolutely right... a lack of pictures and images severely limits the imagination for most of us...
 

click_here

Joined Sep 22, 2020
182
Did you see my suggestion of a reel sensor? If not the commercial product in that post, a hand made one.

Sensing it this way removes dependence on the gauge size (or cable in general), and opens up many easy ways to sense the cable - You just have to measure angular velocity
 

Bernard

Joined Aug 7, 2008
5,788
With either supply reel or pinch roller connected to a rotary encoder, movement detected with a missing pulse detector. Maybe about 600 PPR encoder. Pulse detector time constant adjustable to account for diameters or cable jerkeyness.
 
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