Bending Thin Walled Tubes

[sairsk]

We have to radius a thin walled Aluminium channel. Have any one got some information regarding how to bend tubes and pipes by encapsulating them in some low melting point alloy?? Would appreciate your suggestions and ideas.

 

[rb1957]

i'm not sure "encapsulate" will work ... i think you need to make a temporary tube (but clamping a sheet or plate over the channel, then fill with some stuff (to stabilise the channel as you bend it), bend, then declamp and warm to melt the stuff.

what temper Al ? 2024T3 ?

how thin a wall ? 0.032" ?

other dim'ns of channel ?

bending the long side ? (probably)

req'd bend rad ?

 

[stanier]

Plumbers use a length of spring inside their copper pipes to keep the round profile when bending. Perhaps you could consider a specially shaped spring to suit the channel. Depends on how many you are manufacturing

 

[MintJulep]

Not encapsulate, fill.

It is possible to use lead (health issues) or sand.

"Bendalloy" is a low melting point Bismuth alloy made speciffically for the purpose.

http://www.lowden-metals.co.uk/lowmelting/BendAlloy.html

 

[sairsk]

Thanks for the ideas folks!!!

The reason I have to encapsulate is the channel deforms when we fill it and radius. Its T5 Aluminium with a wall thickness of 0.08.
The problem we are facing is what kind of mold material should I use to encapsulate. In other words I need some reusable mold ( becoz I have to ben some 700 pieces) in which I can put my channel and pour the alloy to encapsulate. Is there a particular material with which I can make this mold???

 

[ornerynorsk]

Use the low temp alloy as suggested and make up a nice silicon rubber mold. This should do the trick.

 

[deanc]

Call around to your local Job Shop(steel,boilers,sheet metal) One of them should have dies and equipment to do this for you.

 

[griffengm]

Sairsk,
There are a couple factors that bear on methods like what is the orientation of the opening relative to the bend, up like V, inside like>, or outside like<? How large is the radius? How large are the flanges of the channel? What kind of bender do you wish to use? Have you talked to Tools For Bending to see if tools already exist? Can some portion of the channel have a controlled distortion? Is this extruded channel or formed?
Without details, we could write volumes and still not answer your problem. Bending shapes seems to be more a matter of control than overpowering.

Griffy

 

[smcadman]

How tall are the flanges on the channel? How wide is the channel? How tight of a radius do you need?

At a previous employer I used to form the arches for atrium windows that were made of anodized aluminum channels. The radii were large, 48" plus, and we formed this repeatedly with a roll/bending roll and UHMW (Ultra High Molecular Weight Polyethylene).

We cut 2 grooves in the UHMW on the table saw for the channel flanges. Then we put the channel onto the UHMW and rolled both of them together in the roll. The grooves "captured" the flanges and kept them from buckling.

The rolls we used were similar to the plate-bending rolls pictured on

http://www.americanmachinetools.com/bending_rolls.htm

I might add that the "open" face of the channel faced away from the center of the radius. We bought the UHMW in 2" x 24" x 96" sheets, and cut about 4" wide strips as we needed them. 1 strip could be used hundreds of times.

Flores

 

[sean01]

A few years ago when I was faced with a similar problem - I was going to use a low melt alloy called cerobend to fill the tube prior to bending until I realised what the cost was !!

In the end I used sand and a hydraulic bender. The material I was forming was 6082 aluminium alloy 45mm diameter 1.5mm wall thickness.

sean