Re: wrong guy, but have servo question.

Hi,

The peak power a servomotor can generate is:

1) P = V squared / 4R

Where P is mechanical power in Watts
Where V is your power supply voltage
Where R is your motor's armature resistance in Ohms

2) Torque at peak power is:

T = (2 times W times RPM) / 1351

Where T is torque in in-oz
Where W is power in Watts
Where RPM is, uh no-load RPM?

Also know:

3) 1HP is 746 Watts
4) 1 HP is 550 ft-lbs/sec.

Example:

You have a 24VDC rated 3000 RPM (no load) motor that has a 1 Ohm
armature resistance. You have a 5 pitch leadscrew. At peak power, how
much thrust will it have (in lbs) and what will be the speed?

Let's take care of speed first. Peak power occurs at 1/2 no-load
speed, so speed is (RPM/leadscrew pitch)=(1500/5)=300 IPM

Use (1) to calculate power: (24 squared)/(4 times 1)= 144 Watts.

Use (2) to calculate torque: (144 times 1351)/1500 = 129.7 in-oz

Use (3) to calculate HP: (144/746)= .193 HP

To calculate thrust: 130 in-oz on a 5 pitch leadscrew is a .03183"
moment arm, 1/(2 times pi times 5). Thrust will be 130/.03183 or 4084
oz, or 255 lbs.

Hope this helps. The above does not take into account leadscrew
efficiency.

Mariss
Geckodrive Inc.

--- In CAD_CAM_EDM_DRO@egroups.com, "Wally K" <cnc4me@u...> wrote:
> Jon, in you last post you said "Wally K wrote:" the following, but
it
> was Ron that wrote it. I am using steppers on my system.
>
> Ron is doing a bridgeport type retrofit and has been trying to
> determine how much HP he will need to move his table and if his
> servos are big enough. And i have been trying to gather
information
> about his system so we could help.
>
> Personaly i think his servos are to small for this type of a mill
but
> i do not have any servo experance so i hesitate to just say it as
> fact.
>
> I have a few questions on servos that you could clear up for me.
> First i thought servos were chopped drives. But it seems that when
> people here talk about a servo rated at a certain voltage, that is
> the voltage they run it at. Example, the servo is rated at 24vdc.
> So they run it at 24vdc.
>
> Second what do the torque curves of a servo look like.
>
>
> Wally K.