Armature knife (Lost in translation)

I am reviewing a JIS style drawing for a slitter line. meanwhile I reached an input for the PLC with the name of "ARMATURE KNIFE".

what is this "ARMATURE KNIFE"?

THANKS FOR YOUR HELP

Where was the machine fabricated?

My guess is that it's some lighting around the knife

My guess would be that its a rotating knife.

another choice for mis spelt armature is the word amateur but can't see how it would relate to knife.

What language was it translated from.

nettogrisen : It is fabricated in USA, It is an input it can not be a lighting

Gil47: my guess is the same. I have seen these rotation feedback before. armature is not a spelling problem I checked it again. The language is pure American English. too much American )

This is a largely unfounded guess but:

How about a slitter anvil drive motor armature thermal switch? What does the input symbol look like? The drafter may have only indicated the location of the input expecting the form of the input to tell the user what the input is.

Another possibility might be this is the status of an armature knifeswitch, or disconnect. Is there a motor on the slitter with a local disconnect?

Keith

Why should he call a thermal switch as "knife"?

The sys. has a local disconnect which I see in the drawings. checking the drawings again I just find out a normal contact with no pos or loc code and another line of discription "DC DRIVE LOCK OUT".

what is a knife switch ?

He wouldn't be calling the thermal switch a knife. He would be calling the slitter a knife. So "ARMATURE KNIFE" would be a shortened version of "armature for the knife motor", in this case the knife being the slitter. As I said it was a wild guess.

A knife switch is a switch that presses a flat blade of metal between two other pieces of metal to make a contact. In the US many disconnects have this design.

What does the symbol of the device providing this input look like?

Keith

The IOs are three, they are:

SLITTER ARMATURE KNIFE
SCRAP CHOPPER ARMATURE KNIFE
RECOILER ARMATURE KNIFE

Thank you

From what you are describing, it sounds like the auxiliary contacts of the disconnect switches are being looped back to the PLC, so the system will know if the various motors are shut off or not.

The terminology is definitely weird though. Knife switches are 19th century tech. I guess I could see the contact blades inside a modern disconnect switch being called knives, but it's not common vernacular.

Yeah, I'd agree. It's probably monitoring the status of the disconnect switch at each motor. Especially since it also says "DC DRIVE LOCK OUT". Do a Google image search for "Knife Switch" and you'll see why a disconnect would be considered a knife switch.



-Eric

I have seen a lot of japanese translations using this type of logic Knife = Cut off

Prince, Let us see if we can figure out what meaning is the most likely. Because there are three different devices listed with "armature knife" then it is unlikly that the meaning is actualy for some type of electrically-operated cutter.

SLITTER ARMATURE KNIFE
SCRAP CHOPPER ARMATURE KNIFE
RECOILER ARMATURE KNIFE

Were these terms translated from another language into English? The strict dictionary definitions are:

Armature: Electric: (a) the part of an electric machine than includes the main current-carrying winding and in which the electromotive force is induced; (b) the pivoted part of an electric device, as a buzzer or relay, that is activated by a magnetic field; (c) the iron or steel applied across the poles of a permanent magnet to close it, or across the poles of an electromagnet to transmit the mechanical force.

Knife: (1) an instrument for cutting, consisting of a thin, sharp-edged, metal blade....(7) to move or cleave through something with or as with a knife.

So, the term is referring to an electrically-operated device that is common to at least 3 devices. It would be possible for the physical devices "SLITTER" and "SCRAP CHOPPER" to actually have an electrically operated knife blade, but I doubt if a "RECOILER" ever would. Therefore the meaning must be for an electrical device needed for at least two different types of device, and common to all three.

I think the term "armature knife" is being used to mean a "motor starter contactor". Motor starters do have a armature (pivoted part of an electric device that is activated by a magnetic field) which moves to cut off an electric current (knife). Motor starters are generally used for all motors above 1 horsepower, and these are probably larger than that.

SLITTER ARMATURE KNIFE
SCRAP CHOPPER ARMATURE KNIFE
RECOILER ARMATURE KNIFE
Armature = Motor
knife = cut out/overload
Inputs to tell you the status of the Motor control relays..... Just what I am thinking.

Badger,

I suppose that if this is a coil-metal handling operation, then a RECOILER could be a machine that rewinds a strip of metal onto a new coil of a different width or diameter. In that case it could have some type of electric cut-off knife. Maybe these all are actually just that: electrically actuated metal-cutting knives.

I think it is not possible to determine with the information given. If we were at the site, we might could figure it out in the context of the plant and the operation.