proximity sensor on sugar mill

labingtone

Member
Join Date
Aug 2002
Location
Manila, Philippines
Posts
113
Hi everybody.

I'm conceptualizing a design to provide shutdown system on cane conveyor. On the cane conveyour there are four cutter installed. When any of this four cutter is stop the conveyour should stop. I'm planning to put a speed sensor on the shaft of the cutter to provide a NC contact to stop the conveyour when any of the 4 cutter is stop. My design on the speed sensor are composed of worm gear and proximity sensor wired to the PLC. Can any one suggest what is the best type of proximity sensor to used on this application?
 
My first thought is "HOW" is it stopped..ie jam, overload?? The starter/drive controlling the motor should react to any of the above conditions (and more). The sensor or encoder/tach is not a bad idea but may not be necessary to stop the conveyor because the cutter has stopped.

If you must use the proximity and worm gear idea that is ok too, count the teeth over a specified time period, if there is NO count or below minimum count during X time period then stop conveyor.

Proximity switch is a proximity switch overall, as long as it can sense the metal and pulse approproately.

Another concept is to use a single piece of metal (or any material that can be sensed) that the prox or photoeye senses once per revolution. If the "once per revolution exceeds X seconds or milliseconds then its in a stopped condition.
 
Any reputable brand of proximity switch will sense the presence of metal. Your application suggests to me that you should be looking at a tubular style. It's up to you to pick the size and style of switch that will reliably sense your target. It's up to you to mount the switch so that it can do the job reliably and not be knocked out of alignment during normal operation. It's up to you choose a model that will operate properly under the environmental conditions imposed upon it. Manufacturer's data sheets provide information about all of those factors. Start there. Call in the salesman/applications specialist from your local industrial supply distributor. Which brand you use is of far less importance than how you apply it, and whether you can get one locally.
 
speed sensing

labingtone

I have used the magnetic sensor and contact feedback to a plc that is shown at this site:
http://www.maxigard.com/zerof.htm

I can vouch for their effectiveness and the cost is minimal as well if you are that concerned about contact welding and the like. This is the same device that I recommended on the contactor feedback post.
 
I assume you mean NOT susceptible... :p

Have you looked into something along these lines?
[attachment]
You may be able to get one that will fit your motor. These offer pretty good protection for (and a great way to mount!) a prox switch for an application like yours. The picture is from RED LION'S PAGE, but is available from a lot of manufacturers.

beerchug

-Eric

ring.gif
 

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