Bend geometry passes through the bend axis

[n.brom]

In de part in the attachment I'm trying to cut away excess sheet metal to produce a rather peculiar shape.

I'm attempting to first create the part curved, then make a flat pattern so the part is able to be cut.

I generated the part first using countour flange, then made an offset plane with the sketch on it.

However once I get to the point of actually cutting it off, it gives the "Bend geometry passes through the bend axis" error. When using the cut command I select the "all" distance with both directions. The error appears to be when generating the flat pattern.

I've tried first creating a normal part, in which this technique works fine. When converting it to sheet metal however it doesn't seem to want to unfold properly and keeps its curved shape.

If anyone could tell me what to change or do it would be much appreciated.

EDIT 1:

Deleting the existing flat pattern did allow me to perform the cut. However now it won't generate a flat pattern. I think I have identified the problem. Because the plane was offset, and the sheet metal curved, it generated a lot of weird edges. I still have not figured out how to either project the 2D sketch onto a 3D shape with all the proper dimensions and/or conversions or how to rebuild the edges so it will fold. Any help in this part would be welcome!

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Inventor 2018

[johnsonshiue · Accepted solution]

Hi! This is actually a limitation and a bug in Unfolder. Inventor cannot properly unfolds geometry like this when there is no flat face to start with. To make this part work, you will need to use a technique I developed a while back, called Double Thicken Intersect. Basically, you cut the part regularly. Then use Thicken/Intersect from both sides to correct the detail faces.

Please take a look at attached part. It should work now. The flat pattern can be created too.

Many thanks!

[n.brom]

Why that was indeed exactly the desired result! Curious technique. I've been attempting to do something similiar but I didn't think of using the Thicken for the role. I was thinking of attmepting somehting to extrude the edges back, but the program didn't want to accept my ideas. I had also attempted projecting a 2D sketch onto the face, but I couldn't figure out a way to cut it perpendicular to the face.

I thank you a lot, this project will require more of these peculiar sheets so this will save a lot of time and headaches.

[Anonymous]

Has helped me with a different kind of fold. Used the thicken trick, but with Join. Works a treat! Thanks for sharing!