Trouble flattening a developable part

[jmoody-2]

I'm stumped trying to flatten this sheetmetal part. Creo 3 M020. It's a simple flat surface with a curved boundary blend, having zero gaussian curvature.

I can see there is something going on with the thickened boundary blend at the corner but don't understand it. Even adding deformation control does not flatten it. Is there a creo 3 sheetmetal tool like flatten quilt that I can't seem to find?

[dgschaefer]

I don’t have Creo 3 yet so I can’t open the part. However, I suspect that Creo may see a boundary blend as non-developable regardless of the actual geometry.

I’ve seen situations where I could verify the geometry was usable for my next task but because it was made with a tool (like a boundary blend) that typically produced complex shapes, Creo wouldn’t do it.

These have typically been things like arced surfaces produced by the sweep tool that Creo wouldn’t see as cylindrical or swept flat surface that weren’t recognized as planar, but the same principal may apply here.

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[mlocascio]

Have you tried creating this part as a Sheet Metal Part?

[jmoody-2]

I’ve received some suggestions that lead me to new insights. For reference, the part was started in sheetmetal mode, and boundary blend control points set to developable.



I thought that a ruled surface boundary blend i.e., having zero Gaussian curvature should be able to unbend. That is not always the case, at least for Creo. This is what I believe to be true from trial and error. The section ends must to be tangent to each other so that the ‘end’ faces of the thickened solid are planer. That unbends fine. That also explained what was going on at the corner that I did not understand. That is for a boundary blend with a single arc in each section. If the section contains more than one arc, all arc ends must be tangent to their corresponding arc on the other side. If only that little detail was provided in the documentation…



While the ‘thin ends’ of the sheetmetal solid that creo creates from the ruled surface boundary blend must be planar to unbend, the ‘thin sides’ created have curvature in both directions i.e., non-developable.



In usual fashion I submitted the case to PTC support prior to this list and still waiting for a response.



John

[mpeterson]

John,

Thanks for sharing. Yes, going to miss this community and support when the exploder is gone.

Mark Peterson

[DavidBrand]

Are you able to post the file that works for future reference?

Thanks

David.