Kollmorgen DC replacement

[bigalow]

I have a machine with a bad Kollmorgen DC drush motor. The motor has a tach and encoder feedback to the control. Question: Is it possible to substitute another brand of DC motor with the same specs, Volts, amps, encoder and tach??? Thankyou!

[Al_The_Man]

Generally DC motors are the easiest to sub, over BLDC or AC.
If the system you have still uses the tach feedback to the drive, then you MAY have to tune the velocity loop, which involves using a +-10vdc analogue signal, battery box, to replace the control command and tune the balance, gain and feedback pot.
If the tach is no longer used and torque mode drives have been fitted, then there is not much in the way of tuning.
Try and get a tach with an output voltage as close as possible as the original, as it can be tuned if within range.
If it is a large sized motor, look for Fanuc or Gettys off ebay.
Al.

[bigalow]

What about updating the motor and drive? The motor is a DC brush with only encoder feedback to the control. The control outputs a diff 10vdc command. I also don't do any contour moves. If the other axes failes then I can update that axes. I would think with the modern drive PID software the axes should be easy to tune??
If I matched the motor spec's and the control feedback a modern package should work??? What would the negatives be???
The Kollmorgan motor needs a rebiuld and I am looking at $5000.00. i bet for $5000.00 I could buy a pretty nice modern motor/drive package.Fun! Thank you AL!!!

[Al_The_Man]

You did not say what system/controller you are using it on, for $5k.00 that must be a pretty big motor?
If the tach is not being used, then it most probably is a torque mode amplifier, which makes things easier.
If the servo loop is closed in the controller then the PID loop is usually tuned in the controller, rather than the drive.
Were you thinking of upgrading to BLDC or AC?
What is the voltage/current/torque rating of the motor?
Al.

[bigalow]

The control is a Teachable 111 made by Brynt. The control uses a 10 Dif command and Line driver encoder feedback. the tack goes to the amplifier. The Specs are 0-115VDC. 2000Rpm max, 8.5 full load amps. 2.0 Amps cont, Torq 2.0lb-ft
The axis spends most of its time in the less 100RPM range.
What drive package would you rec??? AC/DC, Brand?? Machining any adapters that would be needed are no problem. Kollmorgan motors are extremely expensive to have repaired from my experience.

[Al_The_Man]

That is not that big a motor. For well under 5k, you should be able to replace it, let alone rebuild it.
You could keep the existing drive and go with a replacement motor, if you are thinking of upgrading the drive at the same time, you could go with a Brushless DC and compatible drive, Aerotech sell matching motors and drives.
If you stick with DC motor, you could look at A-M-C drive, if you buy a one of their DCBL drives, it will run a DC brush motor, which can be used at a later date for a DCBL motor.
In fact most DCBL drives will run a brushed motor.
The modern drives run in the torque mode of operation which means you do not use a tach.
Generally you need access to the controller parameters to tune the PID loop, in any event.
Al.

[bigalow]

I cannot axcess the parameters of the control. Could I still use a brushless drive and motor?? Thanks Al

[Al_The_Man]

Without replacing the exact motor and tach, anything else may be a crap shoot without access to tuning.
Al.

[bigalow]

So without axcess to tuning parameters in the control I am limited to a DC motor replacement???
I have done some research and I can find DC brush motors with my encoder , tach, torque specs
reasonably priced. Thanks

[Al_The_Man]

Originally Posted by bigalow So without axcess to tuning parameters in the control I am limited to a DC motor replacement???

I would say pretty much so.

Originally Posted by bigalow I can find DC brush motors with my encoder , tach, torque specs reasonably priced. Thanks

That may be the way to go considering no tuning.
Remember, you still may have to tune the inner, (velocity) loop using a battery box, but that should not be a big deal.
see post #34. http://www.cnczone.com/forums/showth...t=17510&page=3
Al.

[bigalow]

Thanks Al!!!!

[bigalow]

I am going to have" Baldor Motors" build a replacement motor for the Kollmorgan motor.
The excisting Kollmorgen DC brush motor has the following specs:
Torque 3ft/lbs cont 8 amps
22ft/lbs stall 14amps
110 volt max
3000 RPM
Tach 12v/1000rpm
Encoder 2500 per rev
The Baldor motor has the following specs:
Torque 4ft/lbs cont 7 amps
25 ft/lbs cont 14 amps
90 volt max
2800 RPM
Tach 12v1000RPM
Encoder 2500 per rev

The Tach is fed back to the drive and the encoder to the control. This is torque control correct?
What about BEMF should I care about value? Any comments much apprieciated!!!! Will it work?!?!? Is it worth a try?