Re: Higher performance systems

Jon,

The other thing being left out of the whole thing is Newton's
contribution; the equal and opposite reaction thing. 400 lbs of
reaction force appearing and disappearing on every acel/decel would
get things rocking pretty good.

Our pick-and-place machine gantry moves at about 4 ft/sec (2880 IPM)
and I estimate the moving part weighs about 100 lbs. The machine
itself weighs 3,000 lbs. We had to put anti-skid pads under its feet;
otherwise it would start walking around the shop like a badly loaded
washing machine.

It uses a toothed belt / pulley transmission and linear encoders. The
belt is 3" wide to withstand the 1 or 2 HP the AC servo motor
delivers to the load.

Mariss

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Jon Elson <elson@p...> wrote:
>
>
> Mariss Freimanis wrote:
>
> >Jon,
> >
> >Indulging in a little "calculator fun" shows 746W (1 HP)
accelerating
> >a 396 lb load to 1,000 IPM in 43 milliseconds; acceleration
distance
> >is 0.36".
> >
> >Identities used:
> >
> >1) 1 HP = 550 ft-lbs / sec.
> >2) 1G acceleration (a) = 32 ft / sec^2
> >3) v (ft / sec) = at
> >3) s (ft)= at^2 / 2
> >
> >
> >
> At first I thought you had made a mistake that the motor was
producing
> a constant 1 HP from near zero speed, which would be wrong in most
> cases. But, after following your calculation, it seems OK. I still
> have a hard time believing this result - it just seems too fast an
> acceleration. Of course, you have neglected all friction and
cutting
> forces,
> which are often not negligible. Of course, a Bridgeport table with
drive
> probably weighs more than 396 Lbs, the table plus saddle (Y axis) is
> even more.
>
> Jon