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ErikClacey14-Alexandrite
14-Alexandrite
September 24, 2012
Question

Flatten round bottom bag

  • September 24, 2012
  • 2 replies
  • 4861 views

Hi,

I need to design a cylindrical bag with a hemispherical bottom. The diameter of the bag is 400mm and the bottom has a 180 hole in its centre. Having contacted the company making it, they want a flat model that they can use as a stencil and cut out the fabric. How do I make this happen? I was thinking that the Sheet metal module would be good but I can't seem to make it work. Also done it in the standard mode as a flat part with half "orange peel" shapes on the bottom but how can I fold it together, with the bottom so all connect properly.


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2 replies

M
MikkoHinkkanen15-Moonstone
15-Moonstone
September 25, 2012

http://en.wikipedia.org/wiki/Developable_surface

http://en.wikipedia.org/wiki/Euclidean_metric

Please use approximation - since you live in Euclidean metric space.

V
Vladimir_G1-Visitor
1-Visitor
September 26, 2012

Hello, Erik.

I have managed to make a flat pattern of a hemispherical bottom by using a flange tool.

I just made a small round flat wall and then added a flange to it with a demanded radius.

In your case it should be 200 mm.

If you want to add some holes on this bottom you should use a filled pattern or just add them on the unbended part and then bend it again.

I hope it would help you.

Best Regards, Vladimir.

2.jpg

P.S.: It looks as if I've just discovered the fourth dimension thanks to Creo Parametric

E
ErikClacey14-AlexandriteAuthor
14-Alexandrite
September 27, 2012

Thank you for the assistance.

E
ErikClacey14-AlexandriteAuthor
14-Alexandrite
September 28, 2012

Hi. Yes the fabric that I'll be using is nonstretch. What I ended up doing, which is probably considered the "ugly" way is that I made the bag in 3d, then cut it into 10 slices. I then measured the lengh of each side, the surface measured height and then made a new part with these dimensions. Ugly but it worked.

    T
    TomD.inPDX17-Peridot
    17-Peridot
    September 30, 2012

    The hot air balloon guys come to mind. In Creo, you can cut up the sphere and flatten the quilt of one of the segments. Since there will always be some level of deformation due to the nature of turning something linear into something spherical, you have to decide how many segments you want the supplier to join. The finer the "mesh" or segmenting, the closer you will come to a true sphere. I don't think Creo will tell you how much "fudging" it does to flatten a quilt. A manual grid mapping exercise may yield better results... or at least do both and compare for a sanity check.

    Funny, however that the manufacturer cannot do this on their own. Are we beginning to rely on CAD too much? Are the true artisans of the world all retired now? ...flying hot air balloons

    http://thewondrous.com/wp-content/uploads/2009/08/0061-600x400.jpg

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