Re: [CAD_CAM_EDM_DRO] Servo motor question

Mina Aboul Saad wrote:

>Hi group,
>
>I'm trying to do this for the first time, I'm planning to change the old
>Fanuc controller on a German lathe, with a new one.
>Servo motors are Siemens with the following specs:
>- Dc Servo, permenant magnet.
>- 1.03 KW
>- 2000 RPM
>- 176 V
>- 7.1 A
>- Max. torque 5 Nm
>With an optical encoder, +5v and 1024 count/turn.
>
>I was thinking of using Turbocnc with Gecko drivers.
>
>Will this setup work?
>

There's one big Uh-Oh! That is the motor's 2000 RPM at 176 V.
That means you will only get 1000 RPM at 80 V, the limit for the
Gecko. You can figure out how this will affect your feedrates,
and then decide whether to go ahead, swap motors, or whatever.
Rutex has a higher voltage servo driver. See
http://www.rutex.com/home/index.html for info on their products.

>What is the required DC supply I need to build?
>

It should be no more than about 76 V for a Gecko drive.

>Which Geckos to use G320 or G340, and what is the differnce between them.
>
>

The G340 has a step pulse multiplier. This is useful if the servo motor has
a high resolution encoder, and the computer is very limited in the step
pulses per second it can produce. Your motors have 256 cycle/rev encoders
that produce 1024 quadrature counts, if I read your data right. At 2000
RPM, that will produce 2000 * 1024 = 2,048,000 counts/min, or 34,133
counts/second. If your computer can produce 34000 steps/second, you
don't need the G340. And, using the step muliplier reduces the resolution
of the servo. But, the voltage problem is the big one.

Jon