# bending and flat pattern

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Hello.

I have a problem with bending and flat pattern. First bending with 90 degrees, next four with 45 degrees next one with

90 degrees and then I can't create flat pattern. Before last bending it's OK. Is this a bug or just my lack of knowledge about bending in Por/E??? Problem occur in 2001 and WF2.
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180 degrees (or 0 degrees?) which is effectively what unbending and flat pattern does.

The other troubling thing you said is that "before last bending it's OK." How did you determine this? Are there a bunch of unbend and bendback features in the part before the last bends? If there are, suppress them all and try the flat pattern again.

David Janes

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OK I'll try again.

I have a large piece of sheet metal, I need to create some kind of frame, which means that all bends should provide me a closed loop. Unfortunetly the frame isn't a square or rectangle so not all bending angles are 90 degrees. (if all bending angles are 90 degrees there is no problem with creating flatpattern). With creating bendings I don't have problems at all. Problem is when I try to create flat pattern from final part (with all bendings). As I said before firs bending is at 90 degrees next 4 are 45degrees an last 2 are 90 degrees. My first thought: maybe I have to complex shape of first wall created by driving surface. So I simplified it to maximum. Creating bendings one by one I was trying to find out which one makes a problem (I was creating flat pattern after each bending). I haven't any problems to create flat patterns after 5 bendings (90 deg and four 45deg). Next bending (90deg) causes a problem. From this moment I can't create flat pattern.

If it helps, here is a picture of final part.

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David Janes

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Have you tried creating the frame as one extruded feature?

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Dnia 2004-07-29 15:15, U¿ytkownik David Janes napisa³/a:

Nope, no effect.

For test I used the simplified model without any tabs, that was a long, straight strip. So that's not it.

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Dnia 2004-07-30 01:05, U¿ytkownik CKERIDES napisa³/a:

and what about flat pattern at the end ???

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"pit" wrote : Dnia 2004-07-29 15:15, U¿ytkownik David Janes napisa³/a: : : > Picture was helpful. By the time you get to the last wall and the flat pattern, : > you have a very long, very thin part which may be challenging the default accuracy : > ratio. Sheet metal is especially susceptible to accuracy problems because of small : > thickness values. Try changing part accuracy to .0001 or even larger ratio, : > regenerating the part and then doing the flat pattern. : : Nope, no effect. : : > Other than that, I see : > nothing that could challenge flat pattern creation. Those tabs that make the : > 'feet' aren't twisted, are they? no very short bends in the notched area? : >

: : For test I used the simplified model without any tabs, that was a long, : straight strip. So that's not it. : I can't really tell from the picture where the start/end break is. If I were puzzling this out, I'd try moving it, putting it between different bends, centering it between bends, then moving it back and forth, till I found something that worked. If you could find ANYTHING that makes it work, you'd have a shot at figuring out what makes it fail.

David Janes

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Dnia 2004-07-30 15:25, U¿ytkownik David Janes napisa³/a:

OK. Thanks for help and suggestions. Now I'll have some free time, so I'll try to play with it and maybe I'll succeed.

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David Janes

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David Janes

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I tried to be even devious and deliberately confusing. For example, on the last flat wall, I constrained the bottom of the sketch to the end of the start wall. Couldn't get it to fail. In any case, I am absolutely sure it is not a simple case of the shape of the part or its bend angles. So, eliminating that from consideration, what else is there? what else could effect unbending? what won't unbend?

David Janes

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David,

Unless I am misunderstanding you, you do not need to move the Insert bar before the flat pattern feature when creating additional walls. Pro/E always maintains a flat pattern feature as the last feature in your model. When you create a new feature, Pro/E will suppress the flat pattern and automatically put you in insert mode just prior to the flat pattern.

Ron

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DJ

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Dnia 2004-07-30 21:45, U¿ytkownik David Janes napisa³/a:

Hello I just came back from my hollidays. If You're still interested :

This is not the latest model but the problem still exist. Model is in WF2.

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Setup>Accuracy>.0005

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Dnia 2004-08-17 00:47, U¿ytkownik SaenZ napisa³/a:

Thanks. I'm wondering why it didn't works before. I was changing accuracy several times and nothing.

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