Rotary motion detector

[drforsythe]

This is not a PLC question, but maybe one of you have seen a product like I am looking for.

I have a portable pneumatic misting system that is used to apply a mist to an extruded product. The mister currently does not have any controls and it can be used on several machines of varying technology. I have been asked to add controls to enable the mist if the machine is running and disable it if the machine is not running. I could add controls to all of the possible machines the mister is run on and design a connector interface that allows it to be run universally from any machine. This would involve several hardware modifications and some programming for the smarter machines. I would like to keep this as simple as possible and would like to avoid connecting the mister to the machine it is serving. I am looking for a device that could be connected to a wheel that would roll when the extrusion conveyor is running and turn on an output if it is rolling and turn it off it it is not rolling. If I can find such a device, I would be able to simply supply power to the sensor and use the output to control the air supply. If I am unable to find such a device, I will roll my own, but I thought it would be worthwhile to ask the diverse talent that monitor this site. Has anyone seen anything like this?
Thanks for reading this!

 

[Robb B]

Several options come to mind. #1 a proximity switch set to read some bump or something on the face of the wheel. Set some programming so if it sees X revolutions in Y time, means the wheel is turning. #2 a rotary encoder. This is more frequently used to obtain the position of the wheel, or the distance it's travelled, but you could use it to detect rotation.

#1 is probably cheaper and easier.

 

[FilthyTech]

depending on your setup, easiest and quickist would be a ct switch that could be applied to whatever motor is running your extruder. Many other options come to mind as well.

 

[OkiePC]

There are devices that incorporate everything you need into a relatively simple package. You might have to attach a flag to a shaft if there isn't already something suitable to use for motion detection.

One example:
https://pharessensors.com/index.php/zero-speed-switch-sensor-model-zs09p-for-conveyors-and-more/

For others, search the web for "zero speed switch"

 

[I_Automation]

If the product is heated to extrude (plastic, silicone, etc) then a non-contact IR thermocouple could be aimed at the exit area and if the product is warm, over a setpoint, run the mist. Even if not heated you might be able to detect the temperature rise created from the extruding process itself.



This could be a PLC thermocouple input, or just a temperature controller giving a COOL signal to turn the mist on.

 

[robertmee]

You just need a rotary RPM sensor....Lots of people make them. Here's a company specifically suited to what you're talking about:

https://superior-ind.com/products/conveying-parts/accessories/belt-speed-sensor/

I've also used Whirligigs....They're magnetic and just mount to the end of a pulley shaft.

https://www.go4b.com/Usa/products/speed-switches/whirligig.asp

 

[Bit_Bucket_07]

You just need a rotary RPM sensor....Lots of people make them. Here's a company specifically suited to what you're talking about:

https://superior-ind.com/products/conveying-parts/accessories/belt-speed-sensor/

I've also used Whirligigs....They're magnetic and just mount to the end of a pulley shaft.

https://www.go4b.com/Usa/products/speed-switches/whirligig.asp

+1 for the Whirligigs. Good product. Good service. You can also get one with a continuously on output when motion is detected if you don't want a pulsed output.

 

[drforsythe]

Thanks for the replies. The products that OkiePC and robertmee suggested are what I am looking for. Again, I have a standalone mister that may run on one of many different machines. The mister currently has no power or controls. I believe I could make either of these devices work without having to change the other machines the mister may be used on. Thanks again.