Cone Refold Adding Bogus Surfaces

[wengerbryan]

We're seeing strange behavior on all of our workstations when using a Refold feature on a sheet metal cone.  Surfaces are (very incorrectly) being added at the top and bottom openings of the cone when the Refold feature is added.  Is anyone else seeing this or does anyone have any clues what is causing it.  The behaviour is the same whether using Contour Roll or Revolve.  The surfaces dissappear when the cone is revolved to a lesser degree, such as 200 degrees instead of 359.  The cone can be revolved to 360 degrees and ripped but that raises a whole nother problem because Inventor does not correctly refold a 360 ripped cone.  Any input?  File attached.  By the way, the surface artifacts show up in the flat pattern as well.

[SBix26]

This looks like one for the Inventor QA folks.  I tried a slightly different modeling method, making the contour flange a full 360° and adding a Rip feature (makes the gap even).  Unfolded easily, refolded easily, but the refold was a completely bizarre mess.  Much worse than yours with the apparent caps on the ends, it was only a partial cone with a bunch of strange angled surfaces attached.

I also tried modeling it using your sketch, but instead of the contour flange, I revolved a surface and thickened it, ripped it, then tried unfolding and refolding-- no joy.  This time I got about an eighth of the cone back, and not from the edge that I had designated as stationary.

Anyone else have a try at it?

Sam B
Inventor 2012 Certified Professional

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[JDMather]

There are techniques (requiring a trick) that do not require unfold/refold.  In the Unfold condition put the geometry that sent you there in the first place and then I'll show you the alternative technique that will work.

[wengerbryan]

In this particular case the user was needing to cut a pattern of round perforations in the unfolded condition.  You can just cut any true round in the flat condition on the file I attached earlier to demonstrate your technique.  Also, when did this behaviour start happening?  One of the service packs?  Inventor definitely hasn't always been this way.  Why doesn't it work to Unfold/Refold after a Rip feature?  I'm meeting with Imaginit about it this morning.  Thanks,

[JDMather]

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@wengerbryan wrote:

1.  You can just cut any true round in the flat condition on the file I attached earlier to demonstrate your technique.  

2. Also, when did this behaviour start happening?  One of the service packs?  

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1. Don't know what this means?  I have never used Unfold/Refold - I prefer to use Project Flat Pattern and Cut Across Bend
2. Looks like a bug in Inventor to me. 

[wengerbryan]

I am always ready to learn, JD, could you take the attached file and create the pattern of cutouts using the workflows you have refered to and attach it to your post.  By the way, adding the perforations brings to light other issues with the refold feature, the hole pattern is not correct on the refolded cone.  Thanks,

[JDMather]

Is the design intent for the perforations to be circular in the flat or in the rolled part (cannot be both)?

Note - if the design intent is for circular in the rolled part then the punch (can't be drilled) will have to be elliptical shape.

[wengerbryan]

The design intent is for the perforations to be circular in the flat which is the reason for unfolding and cutting in the flat.  Most of our cutouts are true round in the rolled part and we don't use unfold/refold for those.

[wengerbryan]

Any more input on this one?  I was hoping to learn something new regarding the statement below:

Spoiler

 I have never used Unfold/Refold - I prefer to use Project Flat Pattern and Cut Across Bend

Is this a method that can be used on the sheet metal cone I attached earlier?

Thanks,

[JDMather]

I've been busy - will try to get back to this one.