perforated mesh dome 4

[meceugen]

Hi,
I have to do a project which includes a 60" diameter and 7.5" deep dome out of 5/64" holes and 7/64" staggered
perforated mesh. The material is steel or aluminum and the
material thicknes is up to 0.074".
Does anyone know who can do it without stamping?
Thanks a lot.

 

[SnTMan]

English wheel?

Regards,

Mike

 

[ornerynorsk]

A spinning shop should be able to do it for you.

 

[btrueblood]

Mount it against a pipe flange, with a sheet of polyethylene behind it "sealing" the flange, and apply pressure.

 

[rb1957]

i think there are some basic questions to be answered first ...

is the sheet perforated before or after being formed into the shape required ? before is obviously much easier to create the perforations, but forming the perforated sheet ??

are you going to stretch form the sheet, ie start with a rectangular sheet and bash the cr@p out of it, smoothing over the buckles that'll form, or are you starting with a bunch of "orange skin" segments to join together ?

how important is conformity to the required dimensions ? (elastic spring back ??)

can you form the sheet in a soft condition, and heat treat ??

i think btrueblood has a nice idea, forming it against a mould, but working with a perforated sheet is going to be difficult. consider too, if it's easily formed, it probably won't stay that way ... you'll have to do a wack of plastic deformation to stabilize the shape.

good luck !

 

[berkshire]

I have done a few of these.
If you only have one to do, then hand hammering on a sand bag or shot bag, followed up by finishing with an air planishing hammer or an English wheel is the is the quickest way. Steel is harder to form than aluminum in that thickness and annealing may be needed with either one.
I do not know where you live, but since most commercial sheet metal shops tend not to do formed work, The skill sets you require to do this, are most likely to be found at an auto body restorer or an aircraft parts fabricator.
If you need more than one, then look at spinning or hydro forming over a disposable form block.

 

[racookpe1978]

Contact McNichols:

http://www.mcnichols.com

They are in Kennesaw GA, a bit northwest of ATL.

They've done metal grating and perf plate for me before. I'd recommend making the plates like an orange peel in "near triangles" with the holes punched in each triangle in a pattern so the holes don't cross a seam line, then bending the triangles into your dome shape and welding the seams.

Cheaper, and faster would be to start with a standard flat perforated plate with a standard pattern, then cutting the triangles out of the flat plate. You'd get lots of places where the many holes would cross a seam though. If that's OK for your process and appearance, then it'd be cheaper and easier.

 

[berkshire]

meceugen (Mechanical)
I have given you information on fabricating a dome in one piece using a raising technique. However if the dome can be made in gores and welded, the time to fabricate would be reduced by 50% and could be done by any competent sheet metal shop.
B.E.

 

[racookpe1978]

60 inch diameter would be very difficult to hammer out by hand: Be hard to get good accuracy and enough force reaching out towards the center of the dome.

Expensive to press it though: You'd need a pretty exotic (large diameter) mold or forming device made.

0.074 thick is doable: I wonder if he needs a "pure dome" (a hemisphere) or could be manage with a dished tank end or pipe "domed head" that's 60 inch diameter. Then, you'd buy the domed head once, use it as a mold to hammer against as many times as you want to make more units.

 

[berkshire]

racookpe1978 (Nuclear)
"I wonder if he needs a pure dome?".
That was my question, A pure dome would require a 72" wide sheet to allow for the radius of the arc and any trimming.
The only folk, I know that will perforate a sheet that size, are Diamond Perforatorated Metals in Visalia, CA.
A perforated sheet is a lot easier to dome than a solid sheet. Using a tank end as a form would take a lot of the fun out of job. However if he only needs one dome that is an unnecessary expense.
B.E.

 

[racookpe1978]

Yeah - I can imagine calling up a flange or tank shop, and asking, "Can we borrow one of your 60 diameter domed heads for just a few days. We need to use it as an anvil for some steel we're beating up against...."