Wrapping Sheet metal around a pipe

Benoit

Hello,

I am trying to use Sheet Metal to wrap an insulation layer around a pipe. We hope sheet metal will be able to calculate the exact dimensions of the wrapping.
I am not a Mechanical Engineer nor very experienced with BricsCAD.

Could someone give me some clues on how to do this procedure?

Thanks a lot!

Jim Canale

I would suggest you go look at this thread: https://forum.bricsys.com/discussion/comment/37068/#Comment_37068
As I recall, when I joined the discussion, I started with a 3D solid of a cylinder. That is not something that can be converted to sheet metal. I had to cut a very thin slot lengthwise, and then use SMCONVERT to turn it into sheet metal. The thread links you to an article which suggests a K-factor of 0.5 for the unwrap. That means half the material will be compressed, and half has to stretch. The K factor is changed in the mechanical browser.

The sheet metal routine creates a sequence of segments (lofted bends) to approximate a cylinder. Now obviously you are not going to be folding insulation in segments. However, you need an accurate developed length for the insulation The more segments, the more the "developed blank" will approach the true length of a continuous wrap. To change the number of segments in the lofted bend you open the mechanical browser, click on lofted bend, and set the number of subdivisions. I have discovered a bug in V19.2.07 which prevents the change in K-Factor and subdivisions. i have opened a support request for this. V17 does not have the problem. I never worked with V18.

Of course the easier way to calculate the length of the blank (insulation), needed to wrap 360 degrees around the pipe is to calculate the perimeter of the neutral line. If the neutral line goes right through the middle of the insulation, add the thickness of the insulation to the outside diameter of the pipe, and then calculate the perimeter of the neutral path. (3.714 x (pipe OD + insulation thickness))

Jim Canale

Of course if you don't want to cut a narrow lengthwise slit in the insulation to allow it to turn into "sheet metal" you can always cut the cylinder in half lengthwise, convert one half to sheet metal, and double the length of the unfolded blank..

Benoit

Hello Jim,

Thank you very much for your help and the file attached.

I will dive now into your ideas!
Thanks again,

Joe Dunfee

The artile in the linked thread indicates that the K-factor in large radius has minimal impact. But, it does not define "large". Many years ago, I tried to work out the K-factor for soft polyurethane foam (a.k.a. Foam Rubber). I don't recall the value, but noted that foam would compress much more than it would stretch. So, the bend radius would be much closer to the outside skin. I suppose you will have to do a test by wrapping your test material into a cylinder and then trimming it. Then finally, measure the unrolled material to see how you need to adjust the value.

-joe