Cone Forming
Cone Forming
(OP)
Has anyone had any experience forming large truncated cones(6 feet diameter x 2 foot diameter x 2 foot tall x 1/4" plate) with a press brake?
I have the flat pattern but I am having a little bit of trouble determining how to check that I am not over bending or under bending the break lines.
Would it be better to use a roll to make the cones?
Thanks for any suggestions
I have the flat pattern but I am having a little bit of trouble determining how to check that I am not over bending or under bending the break lines.
Would it be better to use a roll to make the cones?
Thanks for any suggestions





RE: Cone Forming
RE: Cone Forming
If anyone has any suggestions on anything that could be done to make the cones easier with the break let me know.
Thanks.
RE: Cone Forming
By the time you buy the die steel, program a mill, form the p&d on a CNC mill, polish the working faces, try a few parts, recontour a bit, try again, polish and harden ...
It would be cheaper to just buy a brand new slip roll. They're not that expensive.
Mike Halloran
Pembroke Pines, FL, USA
RE: Cone Forming
360 degrees divided by 40 scribe lines equals 9 degrees, but that is not the degree between the break lines.
9 degrees is the angle if you were breaking a cylinder.
Since the side of the cone is not parallel with the center line, the angle between the breaks changes slightly depending on the height of the cone.
On a 6 feet diameter x 2 foot diameter x 2 foot tall cone the angle between the breaks seems to be about 7 degrees.
RE: Cone Forming
RE: Cone Forming
There exist manuals for layouts of these types of forms from a sheet metal organization called "SNIPS", IIRC. They were not cheap but if you get into this type of thing even once a year they can be invaluable.
I tried chasing this down through Google and came up with this url: http://s
There may be better.
Griffy
RE: Cone Forming
I'm rolling much smaller cones (inches rather than feet).
Plasgears said "Roll the cone if you can find or make the right back up rolls, otherwise you may end up with a spiral distortion."
I have made a die set for my first cone because when I tried to make it on a slip roll I encountered the aforementioned "spiral distortion".
What are the "right back up rolls" in this circumstance? I imagined I'd need to use tapered rolls to truly roll a cone. Is it possible on normal straight rolls? Is there a special way to set them up for each cone or is it a learned skill thing?
I have some much longer cones to make and I'm buggered if I'm making a die set for each one if I don't have to.
Cheers,
Wilson.
RE: Cone Forming
The usual procedure involved preforming both ends to a modest curvature by beating them with a mallet over a cylindrical anvil. Then one precurved end was fed into the nip of the drive rolls, and the blank was driven almost to the other end. The rolls were adjusted for a little more curvature, then the blank was driven back. Forming proceeds the same way; tighten the curvature, drive the blank almost through, and reverse. There was a lot of beating on the curved edges to keep the cone aligned as the curvature was tightened up.
The blank is driven all the way through, making a couple of revolutions, after the straight edges touch.
My friend Francis made it look easy, but he does it every day, all day long, so there may be much more to it than meets my eye.
Mike Halloran
Pembroke Pines, FL, USA
RE: Cone Forming
Its the sort of thing I think I'd like to see a video of your friend Francis doing. Its amazing what some folk can do if they've been doing it a while. Its even more amazing that you can sometimes pick up on what that is by just looking. Its how I learned to TIG aluminium.
Cheers,
Wilson.