Development of a section of a half toroid

[simon]

Hello. I would like to know how to produce a development of a section of a toroid.  My goal is to fabricate fron 1mm thick sheetmetal a half toroid using 72 petals.  Each petal laser cut from aa development of the section. 

[OceanHydroAU]

Why not:

create a petal.

use the rotate command to put 72 of them into a circle

sweep the result half way along a circular path.

If you want overlapping ones, do all the above again, rotating the original by half of 1/72 of a circle, and do the sweep starting the same distance past the first.

[OceanHydroAU]

If you're making this from bits of steel, and want all the shapes you need cut correctly - your friend will be the combine operation - create a new body on each petal, making sure it has been "cut" by its neighbours.

note: I'm not an expert.  There's probably other ways to do this, possibly better.

[simon]

Hi, Thank you for taking time to look at this. When you say create a petal do you mean like this?

Create a torus.

Use the mid plane to split the body into two identical half bodies.

Remove the top body.

Shell the body say 1mm thick.

Then use two planes at 5 degree separation to split the shell,  which creates a petal 1/72 of the complete half torus (360/5=72)?

I can get that far!

Now I want to create a development of the petal shape so I can send it to my laser cutting sub contractor so he can produce 72 petals and I can roll them and weld them into a half torus.

Its developing the petal that Im struggling to do.

[simon]

Hi, Thank you for taking time to look at this. This is the way I've approached the project.

Create a torus.

Use the mid plane to split the body into two identical half bodies.

Remove the top body.

Shell the body say 1mm thick.

Then use two planes at 5 degree separation to split the shell,  which creates a petal 1/72 of the complete half torus (360/5=72)?

I can get that far!

Now I want to create a development of the petal shape so I can send it to my laser cutting sub contractor so he can produce 72 petals and I can roll them and weld them into a half torus.

Its developing the petal that Im struggling to do.

[OceanHydroAU]

No - I would not do it that way.

First, create one petal all by itself.

Then use the Fusion360 commands to duplicate it into a circle of petals.

Then use more Fusion360 commands to duplicate the circle of petals into a torus.

Finally, "chop off" all the overlaps.

** I am not an expert ** - exactly how you would then take the petals to get cut I'm not sure.

I am a programmer - if I had to do this, I would write code (you can do repetitive things with API instructions easier than with a mouse!)

[simon]

I’ve attached a screen shot of the shape. I’ve managed to produce with a flange.  I sliced  the flange and circle pattern the petal 72 times.  It’s about what I want. Now I need to combine the parts and produce that flat pattern.  Took me most of the day to get this far. 

[BrianEkins]

Here's what I came up with.  Most of it is using Fusion interactively without any programming.

1. Here's the model (attached) of the half torus where it's broken up into 5 deg segments and each segment is a developable surface.  The model is attached.  It's created with a single flange feature and as a result, it can be flattened.  The parameter "RingDia" is the diameter of the outer ring and the parameter "TorusRad" controls the radius of the torus from the center to the center of the outer ring.

2.  Because it's created as a sheet metal part I can create a flat pattern, as shown below.
   

3. Now you can export this flat pattern to DXF using the command in Fusion and then use some other software to layout the 72 pieces you need.  I wrote a little script to export the flat pattern body to a file and then read it back into a regular part where I manually patterned it to create the model below.

[OceanHydroAU]

Swish!  

I was having a hard time visualizing what you were doing - now it all makes sense.

(in my mind, I had something more like flat dragon scales - I didn't realize you were OK with bending the steel)

And, "half torus" - LOL - I thought of half a doughnut, like, what's left over after you've eaten half - I even messed up the idea of "half" in my mind!!

[simon]

Brian that’s exactly what I wanted. Yesterday I built this(see attached) and it seems to be almost exactly the same as your solution.  My last problem to solve is to Combine  all the parts together for the laser cutters. I see a long development of Rectangular outer wall with 72 fingers( the developed segment ) attached. Then I can roll the outer wall and weld. Then pull the petals over to form the half torus.  Then pop the inner wall to the fabrication.  It’s how to combine? I might need to produce a smaller petal in the width so when I circle pattern I use 71? But then I’ll need to combine with the outer wall somehow?   Not sure how to do the next bit.  Thank you for looking. 

[simon]

https://limaenvec.autodesk360.com/data/permalink/DT40b1dQT2f858e6a6caedd96460c1361049

Brian. I built this up as a test model.  Can you open it?