electronic clutch?

[pmac10]

can anybody explain to me the principle of operation and make up of an electronic safety clutch between a servo motor and the driven components??

 

[waross]

Google
Browse this:

http://www.warnernet.com/litportal/pdfs/P-1264_cover.pdf

Bill
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"Why not the best?"
Jimmy Carter

 

[pmac10]

thanks waross, had a quick look through but they all seem to be electric brake or mechanical clutch. for your info, im dealing with a packaging machine and the sealing jaws have an electronic safety clutch(in case your arm or somethin gets stuck in it).. i have worked with older versions of this machine incorporating mechanical safety clutch as described in your link. if a product, or my arm, becomes one, with the sealing jaws, how does this electronic clutch work??? i can clear the fault on an HMI after removing the obstruction, need to know the principle of operation to eleiminate false signalling, i appreciate this is maybe specialist subject area, especially not mine ha ha!
all thoughts appreciated.

 

[itsmoked]

So you aren't interested in how the clutch works, you're interested in what triggers the clutch?

Keith Cress
kcress -

http://www.flaminsystems.com

 

[OperaHouse]

Ate these the eddy current clutches that don't use a hard clutch, but a magnetic field to transfer power?

 

[ScottyUK]

Perhaps an overcurrent trip or reverser?


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If we learn from our mistakes I'm getting a great education!

 

[waross]

There are two common types of electric clutch. One uses eddy currents to produce a drag and may be operated with variable slip.
The other type uses magnetism to squeeze friction plates together. Typically a plate lined with friction material will be sandwiched between two steel plates. These clutches are in or out and no slip is allowed.
What the OP wants is help with the electronic circuit that controls the clutch, but there are so many different ways of detecting an obstruction that his question can not be answered without more information concerning the obstruction detection method.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[pmac10]

itsmoked, im interested in both, waross, thanks again for another extremely helpful answer, scotty uk, nothing physically trips, just a message on the hmi, perhaps you could tell me more, poor lubrication of moving parts would eventually lead to this fault message also.

 

[jraef]

There is another technology out there, the magnetic particle clutch, that is very typical for small servo applications like what you are describing. They contain a set of suspended particles that when not magnetized, slip freely but when power is applied, they solidify and lock into the clutch. Applying variable power allows for partial slipping.

This was the only generic reference I could find, but there are plenty of products out there if you do a search on "magnetic particle clutch".

http://en.wikipedia.org/wiki/Magnetic_particle_clutch

"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
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[waross]

Proximity, electric eye, pressure, excess torque, conductivity, capacitance and probably others; there are a lot of technologies that may be used for obstruction detection depending on the application and the designers whim. We need more info.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[pmac10]

waross, this machine is a RECORD flow wrapper, the only electrical connections at the driven components are a heating element and a PT100 resistive probe. could the feedback from the servo motor to the servo drive be monitored and an abnormality be sent to the plc to give a warning on the hmi? im just guessing here but all your replies are helping me build up an idea of whats happening. nothing 'sees' an obstruction regards prox sensors, which is why i posted about poor lubrication also causing the fault.
on sunday, as an afterthought, a production supervisor asked me why, after i had rectified an unrelated fault, why her machine faults when she tries to run at over 98per minute.
the machine max is 150pm and when she showed me i saw electronic clutch fault on the hmi. this ive seen before if a product becomes trapped in the sealing jaws or other jammage, but this time the machine just give up.
you see? nothing in jaws, no blockage, and 52pm under max limit. if i know where this fault signal is generated from i can stop guessing, im sure you can appreciate a high speed production enviroment doesnt allow me time to pursue this,
hope this helps and you have been of great assistance,
thanks

 

[fangas]

This looks sorta like a language (nomenclature) problem. If I'm remembering correctly, FANUC called this an "Abnormal Current In Servo" alarm. the machine tool maker can call it anything he wishes though.

Basically it means that the servo is exceeding it's current limit, and the drive is shutting it down.

I've run into similiar conditions on lathes when they try to hog out too much of a cut. Or, shaving have built up in and around the slides, or lack of lubrication.

Ed

 

[pmac10]

fangas, that sounds exactly like whats happening, maybe the engineering manager should just gimme the freekin manual and i could work this out myself!!!

 

[waross]

fangas may be on the right track here.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[ScottyUK]

That's pretty much what I was thinking, a signal generated by overcurrent in the drive. Fangas did a better job of explaining it than I did. Quite what the machine does with that alarm could be any of a number of things: slow down; shut down / trip; warn the operator; reverse the drive to un-jam whatever is causing the overcurrent; catch fire . Overcurrent would result from anything which increases the load on the motor, so yes, lack of lubrication or the wrong lubricant could very likely be a factor. RTFM might well be the way to go here!


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If we learn from our mistakes I'm getting a great education!