# Thread: "Unfolding" a circular surface to a planar surface ?

1. ## "Unfolding" a circular surface to a planar surface ?

Registered forum members do not see this ad.

Hi,

I have a problem I can't seem to solve

I have two pipes, installed eccentrically. The pipes will be perforated (made holes in) perpendicularly to the inner pipe axis. The perforations have a known phasing and density that will be true for the inner pipe. But due to the eccentricity of the pipes, the holes in the outer pipe will be random.

What I want do do is to use Inventor to "unfold" the outer/larger pipe surface OD, to trace the holes down to a flat plane or surface. Then the plan is to print out this flat surface on a paper, wrap it aroud the pipe and drill the holes manually.

Can you help me with this? Please ask if you have any questions.

2. Attach your attempt (*.ipt files) here.

Do you need the flat pattern for the inside pipe or just for the outside?

I would do as multi-body surfaces trimming the outside pipe and then Thicken (if only need outside).
If need inside too, I would Derive Components and then Thicken.

There is one additional problem to be concerned with, but I will wait for your attempt.

I have made a simplified version of it now, so let's stick to this at first (please find attached). If we can do it with this part, it should be the same with the others.

What I want is the pattern on the outer surface (OD) of the outer pipe.

4. I cannot quite see how your method would work.. ? By using thicken or offset, All I get is a new cylindical shape/surface. I need the cylindrical surface to be bendt down to a flat surface.. I am experimenting with the bend function now. I am hoping that I can split the pipe in halvf, and bend each half down to a flat plate. But it seems hard to accomplish. I dont think Inventor likes bending shapes that are already bendt.

5. Originally Posted by markusiuell
... I am experimenting with the bend function now.....I dont think Inventor likes bending shapes that are already bendt.
I never had any intention of using the Bend feature.
Only took a fraction of a second for Inventor to flatten the part you attached.
Was this the inside tube or the outside tube that you attached? (I assume by the regular pattern that it is actually the inside tube.)

Flat Pattern.PNG

6. Thanks a lot! I will try again when Im back in work tomorrow. Seems easy, but I do not have very much experience with the sheet-metal function (if that is what you used?) and would be very glad if you could supplement me with a little step-by-step tutorial, if you have the time

7. Registered forum members do not see this ad.

There are some Sheet Metal tutorials in the Inventor Help.
Easy enough for the inside tube, but there is a trick to getting those holes on the outside tube lined up with the inside tube.