Author Topic: [ non-lisp ] Rotary die distortion equation  (Read 12608 times)

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T.Willey

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[ non-lisp ] Rotary die distortion equation
« on: March 24, 2009, 12:53:54 PM »
I know this isn't a lisp question, or even a programming question, but I couldn't figure out where to put it, but I thought that someone here might know it.  If this topic gets moved, it's all good.

How can I figure out the distortion between a rotary die and a flat surface?  I have searched, and can't quite seem to find the answer.  My co-worker has done the same, and came up with the same non-answers I have.  It seems like the die dimension are smaller than the flat dimensions along the paper, but we can't figure out a constant formula for it, as all the numbers don't seem to add up the same.

All help is appreciated.  Hope that made sense.  Thanks.
Tim

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T.Willey

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Re: [ non-lisp ] Rotary die distortion equation
« Reply #1 on: March 24, 2009, 02:09:24 PM »
I talked to some of the people here, and it seems like there is no equation.  Sucks.  But we are still searching incase we find some obscure web posting somewhere.
Tim

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Strucmad

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Re: [ non-lisp ] Rotary die distortion equation
« Reply #2 on: March 24, 2009, 05:15:57 PM »
Do you have a pic, or sketch of the distortion...just to get juices flowin :-)

T.Willey

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Re: [ non-lisp ] Rotary die distortion equation
« Reply #3 on: March 24, 2009, 05:24:49 PM »
Not one I can share, but let me see if I can come up with something that is similar.
Tim

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CAB

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Re: [ non-lisp ] Rotary die distortion equation
« Reply #4 on: March 24, 2009, 05:31:38 PM »
Doing a quick search, it looks like a complicated situation involving the material being punched, the size of the hole, and the speed of the punch. Maybe I'm not understanding the problem presented though. Happens all too often. :-o
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T.Willey

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Re: [ non-lisp ] Rotary die distortion equation
« Reply #5 on: March 24, 2009, 05:43:26 PM »
Doing a quick search, it looks like a complicated situation involving the material being punched, the size of the hole, and the speed of the punch. Maybe I'm not understanding the problem presented though. Happens all too often. :-o

That is what I was thinking also, but they say there is no equation.  I think there should be; it might be complicated, but there should still be on.

Do you have a pic, or sketch of the distortion...just to get juices flowin :-)

Here is one I think that is similar to what we were trying to figure out.  With the layout given, what would be the equation to layout the die above?  The pdf is the same as the png.
Tim

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Strucmad

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Re: [ non-lisp ] Rotary die distortion equation
« Reply #6 on: March 24, 2009, 05:58:18 PM »
Bare with me , I have not worked in your industry and I may not be on the same track :ugly:,

Could you explain what I'm looking at ? does the circle need to be punched in that one rectangle or all.

looks like a cool math exercise  :-)

maybe a matrix solution (n,m)  :|

T.Willey

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Re: [ non-lisp ] Rotary die distortion equation
« Reply #7 on: March 24, 2009, 06:02:25 PM »
No problem.

Lets make it simple ( as simple as it can be ), and say the first row needs to be punched as shown, and then repeat at the distance shown.

I thought it might need to be something like that, but my math is so rusty its sad for me to admit that I love math.   :cry:
Tim

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James Cannon

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Re: [ non-lisp ] Rotary die distortion equation
« Reply #8 on: March 24, 2009, 06:04:43 PM »
What 'fuzz factor' are you trying to account for?

Does the circumference of the die not equal the actual linear travel distance across the sheet/part ?

Strucmad

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Re: [ non-lisp ] Rotary die distortion equation
« Reply #9 on: March 24, 2009, 06:13:36 PM »
what would be the origin of the equation be..
why does the circumference come into it? is something rotating? I'm lost
tell me to bugger off if like  :-D

T.Willey

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Re: [ non-lisp ] Rotary die distortion equation
« Reply #10 on: March 24, 2009, 06:15:01 PM »
What 'fuzz factor' are you trying to account for?

Does the circumference of the die not equal the actual linear travel distance across the sheet/part ?

No.  We have a continuous roll that will travel through many rollers before it is cut down to fit within a pouch.  Each set of rollers does something different, and some seem to be in spec at some point, and the loosing spec spacing at the next; until a full cycle comes around, and it is in spec again.

I'm not sure if it's the speed issue that is causing the problem ( or need for differing dimensions between sheet and roller ), or if it is something else.  That is why I was trying to see if there was an equation that would take that into account.  Or even a principle that shows what is supposed to happen and why.  Then maybe I / we / someone could come up with something.  But I haven't even been able to find a true principle.  It could also be my search terms, as I keep coming up with distortion for sound waves.
Tim

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T.Willey

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Re: [ non-lisp ] Rotary die distortion equation
« Reply #11 on: March 24, 2009, 06:21:22 PM »
what would be the origin of the equation be..
why does the circumference come into it? is something rotating? I'm lost
tell me to bugger off if like  :-D

So in the pic shown.  The sheet will feed that way into the roller ( left to right on the png ).  The roller should then make the appropriate cuts to the sheet, so that they pattern shown will be true to dimensions shown.  The roller will rotate about it's center axis, and continue to cut the pattern at the spacing shown.  The origin is not as important as the repeatability of the pattern on the sheet, as we could cut off the beginning of the sheet that doesn't meet spec.
Tim

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T.Willey

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Re: [ non-lisp ] Rotary die distortion equation
« Reply #12 on: March 24, 2009, 06:28:55 PM »
Sorry I might have been clear in the drawing.  The roller is the 5 diameter circle, and the 20 unit long rectangle ( below it in the png ).
Tim

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James Cannon

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Re: [ non-lisp ] Rotary die distortion equation
« Reply #13 on: March 24, 2009, 06:45:00 PM »
I understand the process you illustrate, but having no actual experience, I can't think of any reason there would be variance due to principle or an "ideal situation" and any problems that occur seem, to me, that they would be coming from natural deviance in machine operation and the general chaos of happenstance.

How good are your operators?  That makes all the difference in the world that no engineer or designer can plan for.

CAB

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Re: [ non-lisp ] Rotary die distortion equation
« Reply #14 on: March 24, 2009, 06:48:26 PM »
My thought was that maybe your tolerance is too tight for the equipment.

What is the tolerance?
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