Re: MOTOR SIZE CALCULATION FOR RAPID STOPPING

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Leslie Watts"
<leswatts@a...> wrote:

>Hi Leslie,

Thanks for the advise. I meant 15NM stepper motor (not
15KN). I have
downloaded the software as you advised and am using the rack and
pinion model to simulate my requirement however I am still not
convinced that all is correct as I am getting a very low torque
requirement for the motor of 2.3NM which is definately too small as
I have already tried a 2.0NM motor which is totally unsuitable.
In my application I am using a toothed belt to drive the slide
directly from the stepper motor pulley. Also, there is very little
inertia in the system as I am using ball bearings in the "V" slide.

john
PS The work on your website is really nice.
john_glynn57@...


Hi John

>
> Lets get consistent units and say your moving mass is
> about 68 kG.
>
> If your stepper had zero moment of inertia and friction you could
> accelerate Force/mass = 15 kN / 68 kG= 220 meters/sec^2.
> This is about 22g and does not sound real to me. It would
> be half or less considering the steppers moment of inertia
> but even that sounds not real.
>
> I suspect the system would be limited by a lot of gearing down
> of the stepper to achieve the huge 15 kN linear force. The

reflected

> inertia looking back into the stepper would go as the square of

that

> ratio, so my guess would be that the gears and stepper moments

would

> dominate...The load might be of little or no consequence.
>
> This can all be analyzed by a free program like this:
>
>

http://www2.danahermotion.com/about/pr/releases/KOL516_Motioneering43
0.html

>
> You will need to supply a bit more information such as travel

length,

> moments of inertia of gears, screws, armature, etc to get an

answer.

>
> I'll help run you through it if you want.
>
> Les
>
> Leslie M.Watts
> L M Watts Furniture
> Tiger Georgia
>
> Main page:
> http://www.lmwatts.com
> Engineering:
> http://www.lmwatts.com/shop.html
> Cnc surplus for sale:
> http://www.lmwatts.com/forsale.html
> Carved signs:
> http://www.lmwatts.com/signwp.html
>
> -----Original Message-----
> From: john_glynn57 [mailto:john_glynn57@y...]
> Sent: Tuesday, August 24, 2004 5:55 PM
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Subject: [CAD_CAM_EDM_DRO] MOTOR SIZE CALCULATION FOR RAPID

STOPPING

>
>
>
> I am building a simple grinder with a belt drive and stepper motor
> to drive the reciprocating axis which is 150lbs and want to
> calculate the maximum speed that I can drive the axis using a 15KN
> stepper motor without losing control of the axis due to inertia.

Has

> anyone got the calculations.
>
> john