Machsupport Forum
Tangent Corner => Tangent Corner => Topic started by: Overloaded on January 21, 2016, 03:33:09 PM
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:)
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
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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
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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
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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
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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.
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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.
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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. .........................
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:)
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.
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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
:)
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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.
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Ok, so to heck with the formulas. Something told me it wasn't simple. :)
You call that "crude" !
I guess Michelangelo was a "chicken scratcher". :)
I like your idea !
Would most likely provide enough force but not sure about the kinetics of it.
Questions ...The velocity at the knife looks to be reduced by about 3:1 ?
.. meaning the e-punch would provide more of a "push" than actual impact ?
Relying more on the impact allows all actuation to cease well before the tooling contacts the material relying solely on the kinetics of the mass to complete the cutting.
and making it as fast as absolutely possible.
I was tinkering with a variation of yours but using an air cyl instead of the e-punch.
The cyl would fully extend as quickly as possible leaving the cutters slightly open.
The kinetics of the mass would make the cut and the lower return spring would immediately open the gap so the matl. could continue.
See pic. Something a bit more cruder. :)
I like your pivot pin and return too ... just as I had envisioned. Much simpler than a slide.
Thanks Ian, much appreciated,
Russ
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Something else just came to mind.
Back in 75 (19 that is, not 18) I worked at a place that made fluorescent lighting fixtures.
A 10 stage roll form formed the U channels, CANS for 4' and 8' lights.
There was a guillotine type "on the fly" cutter at the out-feed that had an air reservoir and a rubber air bladder for actuation. Sort of like the air ride on a semi.
The sliding portion of the die probably weighed 200 lb, or more.
Anyway, the air only propelled the mass and probably contributed little, if any, to the actual cutting.
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How about a motor turning a flywheel and an electric clutch to engage/disengage? Or, I had a friend do something very similar a while back using a servo and drive with detect switch going straight to the drive. Its insane fast and does it all day. Get a good braking resistor for sure. I was wondering how it would hold up starting and stopping so quick and so often but been running without issue for a few years now I guess. All day every day or close to it.
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:)Hi Brett.
That is sort of what we are using now. It is massive, somewhat complex and worn badly. It's also an antique. :) Been running since the 60's.
It uses a large motor through a gear reducer to a large 12" clutch/brake that engages a double gear cutting device.
Massive spur gears that are cleared out in the middle with 2 pinch cutter blocks inserted into the body of the gears.
When triggered, it makes 1 revolution and pinches the material in two.
There is a variable speed adjustment on the straightener to insure that the surface speeds between the cutter and the straightener match precisely.
Man, I wish I could draw like you folks, but here is an idea of how it works.
The sketch represents the gear with the center grooved out and the cutter block installed. There would be one mirror image above of course.
The little vid shows the relationship of the gears running and the cutter blocks.
Thanks to ART for Gearotic. :)
Russ
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Also had the notion of a spring loaded design cocked and fired by air cylinders.
Would be instantaneous and plenty of time to get it cocked for the next shot
Hard to decide.
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Am I right in thinking that with your current spur gear system, the cutters travel with the wire as they're cutting? If so I reckon that's VERY neat.
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The trigger and sear would forever be a problem child. You could use an air cylinder arrangment to drive teh hammer similar to what you have drawn.
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The trigger and sear would forever be a problem child.
Why is that?
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Am I right in thinking that with your current spur gear system, the cutters travel with the wire as they're cutting? If so I reckon that's VERY neat.
Yes, it's a very cool set-up. I wish I had a pic of it here.
I searched for hours on the web and never found an image or example.
It is from Germany and has no name on it. Might be custom built .... like a brick **** house.
The gears are about 4" dia. and the pitch is heavy ... Here's a Gearotic example of how the gears are cut. One drives the other and there's a bunch of backlash which makes it difficult to cut accurately without damaging the cutters. Quite a tremendous amount of pressure when the "pinch" comes around.
There is one micro switch to disengage the clutch and engage the brake with the cutter blocks about 180 deg away from the cutting pos. And there's a small speed controlled dc gear-motor with a trigger cam that trips another switch to undo the brake and engage the clutch making one rev and completing one cut. The length of matl. is governed by the speed of the constantly rotating DC motor cam.
The straightener runs continuously as well as the drive to the gears. Speeds are matched so when the clutch engages, the cutter does not "pull" or "buckle" the material.
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The trigger and sear would forever be a problem child.
Why is that?
I see TP .... I think that would work too.
The sear would be quite robust and made of tool steel. Maybe a full .25" of engagement and well lubed.
I have similar in other apps and works flawlessley .... millions of cycles.
I'm curious as Brett.
What issues do you envision ?
Thanks,
Russ
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One thing I like about the spring fired design is near perfect repeat-ability regardless of fluctuations in supplied air pressure and volume.
Russ
:)
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The one thing you will HATE about it is the heavy spring and the wear and tear on the trigger/sear then getting premature firing of teh weight. Been there many times. That spring plus the weight of the hammer will put a very heavy load on the trigger/sear surface contact areas.
Just add in an accumilator tank at the cylinder for air that way the volume is constant at teh hammer location. IF your pressure is dropping out of spec you have other problems (;-) You could simply add in a booster at the hammer location to make SURE the tank is topped off pressure wise each time it cycles. It should run many many thousands of cycles without fail.
IF the Pincher method works for you( bolt cutter style) I would consider a traveling Hydraulic unit or Air unit and forget teh hammer.
(;-) TP
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Just add in an accumilator tank at the cylinder for air that way the volume is constant at teh hammer location. IF your pressure is dropping out of spec you have other problems (;-) You could simply add in a booster at the hammer location to make SURE the tank is topped off pressure wise each time it cycles. It should run many many thousands of cycles without fail.
(;-) TP
That's just how the airbag deal at the lighting plant worked. Just a large bore 3 way sol. valve.
Yep ... might just look into that further.
A bit less complex than the spring deal too.
Thanks
:)
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This one MIGHT do the job (;-) .
(;-) TP
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;D
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Hey Russ
Just playing with some ideas - can I just check some figures please?
@ 150 FPM, it will only traverse .250" in 100 ms.
If my maths is good, one of these is wrong I think. 150 INCHES/min would be .25 in 100ms. 150 FEET/min would be 3inches in 100ms.
out of interest what diameter/material wire/tube are you wanting to cut?
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Hi Ian,
Yep, your math is far more gooder than mine. :)
All the more reason to keep the engagement part of the cycle as short as possible.
The electro, or air acting directly on the cut might be closer to 10 ms getting us back to near 1/4" @ 150 FPM. (I hope ::) )
I don't know how to figgure or estimate the vel, of the hammer, but the material is .25" dia max (for now).
So the "time in matl" would be derived from that.
The toughest to cut is a copper/nickel alloy tube ... .25" OD.
Thanks Ian, much appreciated,
Russ
:)
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Far more gooder, NOW that is a term I can understand.
(;-) TP
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Hey Russ - how about something like this?
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Nice Ian!
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Looks good but you will have following problems with that pin and cam setup.
Just a thought, (;-) TP
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Cheers Brett
<sarcastic-mock-teenage-voice>
Yeah Terry - it's like a scheme suggestion not a design.
</sarcastic-mock-teenage-voice>
;D
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Hey Russ - how about something like this?
That does look good Ian.
I had thought earlier about a similar method that kept the lower pincher fastened rigidly to the sliding <------> assy. The cutting op is about a foot or so from the exit of the straightener so a slight flex of the matl is OK.
What I couldn't figure out was how to precisely match the actuation of the <> sliding assy to the flow rate of the material.
Pneumatic, or hyd would be difficult to "time" unless there was a gripper of sorts to clamp the stock to match the cutting action to the feed of the matl.
Unless you considering just initiating the pinch, then let the feeding of the matl itself do the activation of the <--> sliding assy. ? ? ? Which I do not think would work very well.
Encoder following of sorts with a servo and screw (like Brett mentioned earlier ?) would be a bit overly complex ... I think.
Timing is critical. Maybe a mechanism like this on a free floating spring centered platform. Adjust as close as possible, the let the free float compensate for the variations ?
Just wondering what you had in mind for these issues.
Nice drawing too !
I did some "hammer" experiments while the wife was shoveling ..(grin) ;D will post a pic and and notes soon.
Thanks Ian,
Russ
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I did some "hammer" experiments while the wife was shoveling ..(grin) Grin will post a pic and and notes soon.
Just remember, this is a kid friendly forum. ;D
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:D
Man, if I could only see inside that head of yours ...... I'd wear a welding helmet. :)
That's classic :)
I will be careful of the pics. ;D
Thanks Brett, I needed that.
Russ
:)
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;D
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This is what I was experimenting with.
Left illustration was a temp set-up clamped on the table to compare impact / mass / return spring relationships.
I only used 1/4" valves and tubing, so easy enough to go bigger if necessary.
It had a surprisingly heavy wallop. I'm making 2 new cutter blocks to verify by actually cutting some sample material.
On the right is what I thought I would put together.
The outer tube will be a surplus steel hydraulic cylinder.
Threaded cap on the top for the air fitting.
The weight itself will have a groove with an o-ring or lip seal.
The spring connecting pin will pass through the weight and through 2 opposing slots in the outer tube to
prevent rotation of the weight keeping the upper cutter block aligned.
The springs will only be heavy enough to reliably return the weight to its upper position.
The position of the exhaust ports are positioned to allow the hammer to return the blocks to the open position instantly, with no interference.
A special quick exhaust valve might not be necessary at the inlet port as there will be 5 seconds or more before the next cycle.
See anything that could use improvement ?
This is the least complex solution so far ( I think)
Will be searching for the recommended metal and treatment for the cutter blocks to withstand the beating. The cutting edges aren't the major issue, it's the flat parts of the blocks that slam together that concerns me.
Still tryin to draw like Ian .... some day. :)
Thanks folks,
Russ
:)
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To further simplify:
Basic 4 way valve, quick exhaust on the extend stroke, spring just enough to carry the weight.
When fired, the cyl extends fully, the weight continues on compressing the spring and completing the cut (with some spring travel left), then immediately rebounds to an open position by the spring.
De-energize the valve and retract the cyl, standby for the next cut.
Will have a tube with slots to guide the weight as before.
This would eliminate possible issues with the longer springs and positive retraction.
This will be fairly easy to try.
Russ
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I reckon you're on the right track there Russ - looking good.
Still tryin to draw like Ian .... some day. :)
Those are great drawings. Is that Rhino you're using?
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I think "9" was also the price. :)
Not very powerful, but neither am I. ;D
Thanks Ian,
Russ
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Hey Russ - take a look at this...
http://www.youtube.com/v/yKAq-zS77hg?hl=en_US&version=3
if you look at the 1:50 mark, they're PULLING the wire through the straightener a length at a time and then chopping it whilst its stationary.
Ian
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That's a very fancy set-up there !
We have a few similar 4-Slide Machines but none that does the rolled threading.
The major difference that makes the incremental feed problematic is that our cut length is 12' for shipment outside and 20' for in-house processing.
Another is the spools weigh about 600 lb.
Would be quite a rework to start and stop the straightener to control the feed length and to control that 600 lb spool accel/decell.
VERY neat though, thanks for posting.
Cool.
Russ
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No worries. Whatever you do though - we're gonna need a video when it's finished :)
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Hi Ian,
I did a little testing.
Ram is 2" dia. x 8" long, about 7 lbs.
Cylinder is 2.5" bore x 2" stroke.
Pics show the cyl extended with the recoiled gap and the "internals". Will experiment with various springs as it looks to provide a more than adequate wallop. Yep, all them clamps ARE necessary. Even slid them slightly. :)
Pretty well instantaneous but there is a little oscillation as the spring settles out right after the slam. But I think it will be well clear of the material ... hope so. Might need to figure a way to dampen it without affecting the recoil speed. ::) Its a bit worse when vertical.
Tried to do a vid, I need luck with that.
Next, I'll set up some actual cutters, too busy right now.
Russ
dang video is too large. Will get another.
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Tried to do a vid, I need luck with that.
Pathetic ;D
dang video is too large. Will get another.
c'mon Russ - pull finger ;D
and I want to see it on youtube - not some gigabyte download... let's at least pretend we're pro's here ;D
Hell even Hood can manage that... ;D
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:D
Here's a shorter vid. I don't have a fancy phone. Never used this video camera deal much either. ::)
Need to set the resolution down I guess, files are huge.
:)
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looking good. That should do it.
I don't have a fancy phone either - but hey Russ at least we can do videos that don't look like they've been shot through a hole in a fence! ;D
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any progress Russ?
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I'll tell you how fast it is, I just watched the video and got a black fingernail........ ;D
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:D Good one Brett :)
I made a set of cutter blocks out of some D2 and heat treated them.
Set them in a small fixture to maintain the proper alignment.
It sends the cat a runnin', but it is not quite adequate for positively cutting the tube.
It will work very well on the smaller stuff using the Electro approach, so the job was not a complete blowout.
Will need to experiment further regarding the larger, tougher material. :-\
Russ
:)
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Pretty well instantaneous but there is a little oscillation as the spring settles out right after the slam. But I think it will be well clear of the material ... hope so. Might need to figure a way to dampen it without affecting the recoil speed. ::) Its a bit worse when vertical.
How about using two springs with different spring rates, to minimise bounce?
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With teh hammer approach using inertial weight you will not have NEAR the cutter power as a levered (bolt cutter style) cutter. There are bascially only 2 methods to improve the cutting power of a hammer.
Increase the speed of the hammer ( larger air intake at the cylinder(more, faster flow) and a LARGE OPEN exhaust port area)
Increase the weight of the hammer ( not always the better choice )
Just make sure you keep your pinky away from that area.
(;-) TP