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Square to round cone sheetmetal layout

All,

I am the author of the Cone Layout program (see pulserate.com) which can calculate the layout or flat pattern projection of a cone with tilted ends. I am currently working on a new version that can also generate square-to-round "cones". I have succesfully updated the finite element model (FEM) that is used by the program to generate the layout:

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However, but noticed that the resulting layout is difficult to bend/roll. Is it generally necessary to make incisions at the corners of the squared end of the cone in order for the square-to-round cone layout to bend properly, or did I just make a mistake in my model?

All suggestions are highly appreciated!

Regards, Joris

Reply to
Joris van der Sande
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I don't have a clue to the answer to your question, but please advise when you solve it and it is available. I'm going to have to build an

8'x8' square to 6'dia. convergence section for an existing wind tunnel. It will be laminated plywood rather than sheet metal, but it would likely be adaptable for my purpose.
Reply to
Charly Coughran

Joris:

Not just any three-dimensional shape can be "flattened" out. Prismatic shapes can be and certain specific curved transitions can be. But the gradients must be such that the surface does not have a compound curvature. In other words, you can flatten out angles and you can flatten out cylinders and cones, but that's about it. You can't, for example, flatten out a sphere. So certain transitions may be impossible to form from a flat sheet without creasing and/or buckling.

Don

Reply to
Don A. Gilmore

Correct, and in actual practice the creation of such shapes out of sheet metal is known as "forming" instead of "bending". Deformation is probably a better name for it. Some CAD programs can apply "forms" (basically like tools on a press) to sheet metal to simulate the results of forming, but it's only simulation as it can't account for variations in resultant thicknesses where stretch occurs. And even the most complex and expensive CAD of which I'm aware can't take the resulting shape WITHOUT the parametric history and give you a flat pattern and a forming tool. If you COULD do such a thing with Joris' algorithm(s) then he should be able to sell that to any number of MCAD software companies for a pretty penny.

BUT . . . although I'm not sure I understand Joris' question about "making incisions at corners", indeed of course "bend reliefs" -- places where material is incised to allow deformation -- ARE used and often are necessary at corners in actual sheet metal work. Or perhaps (and probably) I'm stating something already very obvious to him (Joris).

Mark 'Sporky' Stapleton Watermark Desing, LLC

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Reply to
Sporkman

Look up a program called "sheet lightning" which would do what you wnat. IIRC there is another one caleld plate and sheet pro as well. Geoff

-- Catapultam habeo. Nisi pecuniam omnem mihi dabis, ad caput tuum saxum immane mittam. I have a catapult. Give me all the money, or I will fling an enormous rock at your head

Reply to
Geoff M

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