On 6/16/22 21:57, John Dammeyer wrote:
Hi Gene,
Quite right. That link I posted used a table while in fact, as you pointed out, the mass
is mostly on the outside of a flywheel with spokes. I would imagine at there is some
average where if it's a 300 lb disk that is 24" might be the same as a 36" disk
that is 400 lbs.
Think of a fly press for example with a clutch that engages the tooling. Even
if it does take 5 seconds to get up to speed, the clutch engages, the tool
moves down and punches and moves up and the clutch releases. Even if the speed
slowed down by 20% when the clutch released then assuming linear acceleration
now only 1 second is required to bring the speed back up. At 50 RPM (0.83
seconds per rev) then you could do another punch stroke 1 second later and so
possibly run 30 strokes per minute.
That jpg chart I included suggests with 100% efficiency and no real friction
that 45 oz-in are required. Seems very low to me hence the questions. Even
if I did use a stepper motor and went 16:1 to bring the RPM down to 800 RPM the
motor could easily be a size 23 300 oz-in.
Could that actually bring a flywheel up to that speed in 5 seconds?
Maybe, if you had a more non-linear control that most, but I'd stay away
from steppers
because if it slips a step, it will stop. I'd much rather have an
encoder right on the motor
like I did on the go704, and in your case get a 1 or 2 horse treadmill
mill motor, drive it from
around 125 volts from an unregulated DC supply, controlling it with one
of Jon's PWM-Servo
drivers (Pico Systems) for long lasting dependability. That combo can
turn my go704 mills
spindle from 3k fwd to 3k in reverse is 350 milliseconds. I've a 5"
chuck on TLM, and
essentially the same circuit with a few less amps available, can turn
that 5" chuck doing
500 revs, in a full reverse, or back foward, in around 400 milliseconds.
That servo driver of
Jon's is a full 4 quadrant control, recovering the energy in the motor
when bringing it to a
stop, and charging the supply's filter caps up to around 170 volts in
about 100 milliseconds,
but it then uses that energy recovered to re-accelerate the motor in the
other direction.
You don't need the reversal so that energy is not there to recover, it
must come from the
wall socket. I hear the iron chirp from the PWM-Servo going into current
limit at around
18 amps for a small fraction of a second. That means your service will
need a 25 amp
breaker to stop the nuisance trips. IOW, that 1 hp motor is for a few
milliseconds
making right at 2 hp, and its been doing it, without even fresh brushes
for around 7
years on the go704 now. TLM about a year more. But I've also broken lots
of drive
parts until I put the limit3 in its hal file.
So that's how I would build your setup, basically using the current
limiter of Jon's driver
to set the limit. And if It has time to spare profiling the on start
signal with a limit3 can slow
it just enough it won't hit the limiter and that could probably get your
service breaker
down to 20 amps, allowing a 10 gauge feed line legally.
Take care & stay well John.
Cheers, Gene Heskett.
--
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author, 1940)
If we desire respect for the law, we must first make the law respectable.
- Louis D. Brandeis
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