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Electro-Punch design
« on: January 21, 2016, 03:33:09 PM »
 :)
If you've got a moment ................................

I have a little device made by Black and Webster called an Electro-Punch.
Pretty cool and works very well. (pic soon)
Its basically a simple 220 VAC solenoid that gets energized for a few milliseconds with a spring return. Some use a supplied controller to vary the impact which can also be varied by positioning the work at differing distances within the available stroke.

I want to possibly build one that is maybe 2 to 3 times as heavy.
I could scale this one up dimensionally, but it would probably not be correct electrically.

Question is, would there be a formula ... or ? ? ? to determine the coil length, diameter, wire size, # of winds, resistance, ? ? ? ? ?

The one I have has a core (weighted inner moving mass) that is about 2 lbs. and strokes about 2".

I'd like to make one that is about 6-8 lbs.

This would fire once every 5 seconds ..... or so.

Is there a simple way to determine the dimensions and electrical requirements for optimal performance ?

Thanks,
Russ
 :)
 
edit: added pic. mine is only slightly different and is 220 V
 
« Last Edit: January 21, 2016, 03:49:50 PM by Overloaded »

Offline BR549

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Re: Electro-Punch design
« Reply #1 on: January 21, 2016, 05:41:58 PM »
WHATCHA building ??  One of the things you you will find harder to overcome is teh weight of teh hammer needing a large return spring then it take s a LOT more solenoid power to over come the spring AND add velocity to teh hammer.

I will take a look in some old books but most of teh formulas for solenoids and coils  should be on the web.

(;-) TP
Re: Electro-Punch design
« Reply #2 on: January 21, 2016, 06:20:36 PM »
Thanks Terry, I'll dig around a bit more.

I did see another method using air where you pressurize both sides of the piston (regulated to keep the ram retracted) then vent the rod side through a large port quick exhaust dump valve.

Might experiment with that also.

Basically cutting tubing and wire on the fly (150 fpm +/-) coming from a coil and through a straightener. Must happen quickly ...BAMM .. or is that BOOM.  ::)
Two opposing sharpened blocks, sort of like lineman's pliers. 70 deg incl. angle and sharp, one block stationary and the other attached to the hammer.

The entire cutting assembly should only move laterally a fraction of an inch during the cut, then retract for the next cycle.

Just figgurin'.  ::)

The punch I have works for the smaller material but seems to be about 50% of what I need for the larger stuff.  But I'd like a little extra.

Thanks Terry,
Russ

Offline BR549

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Re: Electro-Punch design
« Reply #3 on: January 21, 2016, 08:28:18 PM »
Are you sure a traveling shear or saw would not be better ?  Any sort of tubing would be calasped on the ends ?

Just a thought, (;-) TP
Re: Electro-Punch design
« Reply #4 on: January 21, 2016, 08:49:03 PM »
The collapsed "pinch off" is no problem. We're just cutting tons per day to 12' lengths.

We have "on the fly" saws but they don't work well at 150 + FPM as there is no time to retract the saw blade out of the material without a longer slide than I have room for.
Also trying to minimize the complexity. 1 input and BAMM .... no motors/belts/saws to sharpen/actuators/ knives/  ....+++++++

This material is zooming,, the cut needs to be near instantaneous.

Offline BR549

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Re: Electro-Punch design
« Reply #5 on: January 21, 2016, 09:02:27 PM »
IF it is traveling that fast then your punch hammer at that weight is going to be slower than the material is traveling . UNLESS yo hve one really BAD punch hammer solenoid and rebound spring (;-) And thenyou still may have a binding problem from teh traveling material side pushing on the punch.

Let me know what you figure out.
Re: Electro-Punch design
« Reply #6 on: January 21, 2016, 09:46:32 PM »
I'll get a pic ... I don't think you're seeing what I'm meaning.
No bind, it's over in a fraction of a second.
The timing is such that the coil is de-energized just before the hammer reaches its extended pos. The required momentum is established by then.
So, as soon as it bottoms out against the cutter blocks it rebounds.
The pic I'll get just shows the actual cutting edges.
There will also be solid blocks above and below to stop the ram exactly where the cutting edges come together.

Back in a min ... or 2.  .........................
Re: Electro-Punch design
« Reply #7 on: January 21, 2016, 10:02:01 PM »
 :)
The sketch shows the lower cutter milled into a solid block to provide solid stops for the hammer. The top one will be the same.
Re: Electro-Punch design
« Reply #8 on: January 21, 2016, 10:33:02 PM »
  And thenyou still may have a binding problem from teh traveling material side pushing on the punch.
 

The entire unit will be on a slide, or possibly just a simple pivot to allow allow it to travel during the actual cut.
@ 150 FPM, it will only traverse .250" in 100 ms. .... which is about all the time it takes. (maybe even less) But, I can give it an inch or 2 of freedom.
Russ
 :)

Offline stirling

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Re: Electro-Punch design
« Reply #9 on: January 22, 2016, 07:59:35 AM »
Question is, would there be a formula ... or ? ? ? to determine the coil length, diameter, wire size, # of winds, resistance, ? ? ? ? ?

Hi Russ

There is - but (to me at least) it gets brain hurt complicated.

How about using the one you've got but use a lever to increase your cutting force?

(crude) picture attached.