Servo indexer motor or drive?

[itsmoked]

Got a 10 year old indexer for a big machining center.
It has a 19" rack mount controller/drive.
A cable runs to the indexer proper.

The motor is connected to a big indexer that holds a part being machined. When needed the part can be rotated (indexed) to some new position for the next machining move.

Worked just fine three months ago when the indexer head was removed from the machining deck.

Reinstalled it and... nada.
I had the motor pulled.
You can turn it with a weee bit of effort unpowered.
When powered, but not commanded, it is considerably harder to turn.
When it's commanded to index it hums and is very hard to turn by hand but doesn't turn on it's own.

I thought maybe the brake was toast so the motor couldn't turn because of a normally ON brake or because the brake might be rusted to its disk or something. But this seems out the window since it can be turned with fingers while unpowered.
I am unsure whether the motor is DC or Brushless. I'm suspecting no brushes.

There isn't an obvious encoder but there has to be so it must be inside or it's a resolver or something.

Speculations of the cause of these symptoms?

1) Brushless three phase and the drive has a blown phase?
2) Motor has an open winding?
3)

Keith Cress
kcress -

http://www.flaminsystems.com

 

[Brad1979]

To me it sounds like you are commutating correctly. Could you have connected one of the motor leads or one of the encoder/hall leads incorrectly?

 

[jraef]

Stepper motor with the controller stuck on one step? That would have a braking effect when powered on.


"Will work for salami"

 

[mikekilroy]

What I tell customers 3-4 times a week: "usually the last thing we do is why something is now broken." so you took it off and now put back and it does this.

If stepper, you'd more likely not say turns with wee bit of effort when off, but more likely it bumps around with wee bit off effort when off so i would say probably not stepper. also, 10 years ago "large indexers" probably didnt use steppers.

If dc brush motor, then missing motor lead is not likely or it would not hold pos or hum at your when told to turn, nor missing encoder wire or it would ZING run away and your fingers would have been in danger trying to move it....

so probably ac synchronous (brushless). 1 missing motor lead would make it meet all your symptoms. 1 missing feedback wire would too if it is so old that 19" rack does not have 'loss of feedback' protection, but this is far fetched.

Can you list the mfgrs or part nos of the stuff? Might help too...

So my money is on a missing motor phase wire.

 

[mikekilroy]

oops pushed enter too fast: or the 3 motor phase wires in incorrect place now (phase wrong) - would also meet all your symptoms

 

[itsmoked]

Thanks guys.

Further: After he did the requested removed-motor-tests he reassembled the motor back into the indexer and what-the-hell tried it. It ran perfectly. He then siliconed the motor side covers and cable entry and tried it again. It no longer works.

The driver side is a classic circular connector. Motor end is terminated to the motor windings inside the motor housing. No connector.

He re-opened the motor side to gain access to the wires on that end, disconnected from the driver and ohm'd the cable end-to-end. He didn't find any opens. He also ohm'd the motor windings and they all met the factory specs, so none of them are open.

In finding the motor specs he discovered the motor is indeed a stepper motor.

So Brad, the cable is all made up and preassembled with a connector so it's not a misconnection situation.

Jeff you nailed the motor type! That explains a lack of a brake.

Mike; Not a synchronous or brushless AC motor which I was thinking it was too. I still believe it's a bad connection in the cable makeup. One that makes and breaks with cable motion. Probably near the motor but possibly near the drive too. I have him trying to index while moving the cable carefully over its length.

Thanks for your speculations all. I'll let you know what transpires.


Keith Cress
kcress -

http://www.flaminsystems.com

 

[itsmoked]

Oh Mike: It's a Richmill system. The motor appears nameless.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[Compositepro]

With no encoder feedback I was going to say that it is probably a stepper motor. That also means that the controller needs to find a "home" position in order to find itself. The drive may be disabling itself if it can't find "home", which it needs to do at every power-up.

 

[itsmoked]

Thanks Compositepro.

The jury is back in from deliberations!

It's the connector that connects the cable to the controller. When he worked his way gently down the cable, while trying to get a cycle to run, as he flexed the cable at the connector.. Bingo. It's a circular AMP military type connector. Man.. Have you guys seen what these things cost now days? You can easily drop $150 on one half of a connection.

It's one of those assembled cables made of a bunch of wires in a flex conduit. Those always suffer from the short wire bearing the entire tension of the whole assembly. Weak.

Thanks for all your insights!

Keith Cress
kcress -

http://www.flaminsystems.com