TJ:
Slightly off-topic: Your explanation of isopulse technology explains at
least partially why RC based EDMs produce pretty darn good finishes-- because
the energy per pulse is mostly constant. The capacitors dump their energy, the
arc goes out and that's it. The short pulse durations do cause greater
electrode wear, even with positive polarity on the electrode.
I ran a Charmilles D-10 and a D-20. The D-10 was an Isopulse machine and I
think the D-20 was also. I also programed and ran an Agie AT-50, which was
later re-branded as the U-100. I don't remember the name of the pulse
technology it used. Electrode wear was remarkably low on the Agie.
Pete Gruendeman
--------------------------------------------
On Wed, 3/9/16, TJoseph Powderly <[email protected]> wrote:
Subject: Re: [Emc-developers] EDM gap control (Control parameters)
To: "EMC developers" <[email protected]>
Date: Wednesday, March 9, 2016, 12:10 AM
Niklas Pete,
if you want ISOPULS ( isoenergetic pulses that
have uniform craters )
then all the worry
about frequency is useless
if you dont need uniforn surface finish, then
ignore this comment
if you
DO want uniform surface finish, then you do not use
repetitive
pulse grnerator
instead, you wait for ionization ( a kind of
indetermonate latency of
conduction)
THEN start decrementing the ontime. This was
the joules delivered are
equal ( the energy
is equal )
Once the ontime is finished, the
current is turned off and the off time
is
waited
THEN you turn on a tiny exciting
voltage and wait for another ionization
(
and voltage drop ) before starting the next ontime current
flow.
some pix:
http://www.edm-products.com/Dielectrics/ifase/ifase_1.htm
look at figure 3
if you wait
for the ionization (wait for the voltage to drop)
and then deliver current for the duraction of
'ontime',
the energy delivered will
be uniform, and the surface crater will be uniform
if not, the energy per pulse in non-uniform, to
the extreme that some
pulses deliver nearly
no energy!
see figure 4,
when the strategy is isoenergetic, the current
waveform will be uniform
and the leading
edge of the voltage will vary.
if not
isoenergetic, the leading edge is static on the scope,
but the current wave form will vary.
On 03/09/2016 01:59 AM,
Nicklas Karlsson wrote:
> A
microcontroller with suitable peripherals for power
conversion is cheap and do the work much better. I know
about: stm32f334, Infineon xmc4xxx something, maybe texas
instruments and Microchip.
>
> I am working with stm32f334. It have a
high resolution timer equal to about 4GHz clock frequency
with a lot of triggering options, DAC, fast comparators and
cost maybe a few dollars. There are also cheap development
boards available.
>
>
I guess spindle off/on signal may be useful to turn off/on
generator and some m-code is useful for the parameters?
>
> Regards Nicklas
Karlsson
>
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