PDA

View Full Version : Oval Tube



Stepside
12-11-2002, 02:35 PM
I have a need to change some 1.5 inch diameter x .125 wall x 18 long tube into an oval cross section. Parts should be visual close in shape. I need some suggestions on how to proceed. I can access a 50 ton
press if needed as well as torches and furnaces. Appearance is important, but it should retain as much structural integrity as possible.
Thanks
Pete

metal mite
12-11-2002, 02:59 PM
Step,

We did some aluminum tubes for a mock-up.

We plugged one end, filled them with water, froze them in the freezer, and ran them thru the bending rolls fast before they melted.

Don't know if this will work with steel.

mite

Al Messer
12-11-2002, 03:05 PM
You can also fill it with table salt and plug the ends and then form/deform it. Rollers would be best to use I'd think. Salt will desolve out in water.

SGW
12-11-2002, 05:49 PM
How "oval" does it need to be, i.e. how much do you need to flatten it?

ShavingMaker
12-11-2002, 05:57 PM
try rollers to set the flat, then pull an oval mandrel thru to size the inside as they do for D.O.M. tubing. Use a lubricant too.

Dr. Rob
12-12-2002, 03:03 AM
I´ve long looked for a source for oval tubing. Haven't found the source, but do know that it can often be found at places that sell used boutique interiors and office furniture. It seems to be manufactured to the same standards as the ubiquituous DIN 2395 stuff- welded and cold drawn, smooth exterior, roughly 1.5 to 2 mm wall. It is usually perfectly elliptical, as opposed to flat-with-round-ends.
This might be a dumb answer, but hope it helps someone anyway.

CompositeEngr
12-12-2002, 03:07 AM
Aircraft Spruce and Specialty

4130 Streamline tubing:
1.685x0.714 wall 0.049
P/N 03-11600 $11.60/ft.
Various other sizes also. Not exactly oval, but thinner on the trailing edge.

Also have Aluminum 6061T6 2.697x1.143 0.049 wall.
P/N 03-40000 6' $49.90

Thrud
12-12-2002, 04:53 AM
Albert
Is that 18" or 18' - what material? 18" is going to be hard enough to do. the best way would be to make rolling dies to the shape required. I press could do it, but cosistancy could be a problem without making a die set up. You can squish it with ureathane filled dies in the press, but how much it gets squished is the issue as well as the resulting shape.

Without knowing any more - make rollers up to do the job.

NAMPeters
12-12-2002, 10:15 AM
May I suggest forging the shape using a bottom swage and a top swage machined with the contour desired. It will take a little math to calculate the major and minor axis of the ellipse. You will need a helper or two to move the tube and hold the top swage.

Have fun and safety first.

------------------
Neil Peters

tonydacrow
12-12-2002, 10:47 AM
If you need to fabricate alot, why not make a set of rollers with the required cross section?

Rich Carlstedt
12-13-2002, 09:24 PM
Quick way is to make up a channel for the tube that is wider than the tube diameter and shorter than the tube diameter and as long as the tube. Say 3 inch wide X 1 1/4 high inside x 20" long. Lay the tube in and cover it with a 1/2 thick plate and press it hydralically. The press will stop when it hits the channel as it will not compress (easily).
Take out your compressed tube, if you want more oval, remove some of the channel height.
Once you have the right one, ALL tubes will be the same...simple and works as fast as you can reload