Bending Thin Walled Tubes 1

[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.

 

[aeroUB]

what kind of Dia. and wall thickness are you talking about here?


"encapsulating them in some low melting point alloy"

Is this some kind of a requirement or something?

 

[MikeHalloran]

You can buy small ingots of bismuth alloy from Small Parts. Some of the available alloys will melt in boiling water, which shows you how to recycle the material.

Once you have a tube or pipe filled with soft metal, bending it is as easy, or as hard, as bending a rod of the same diameter, and you can use the same tooling.

Taking that one step further, there's no reason why you couldn't stick a thin aluminum channel into a tube, fill the space between them with bismuth, bend the assembly, melt out the bismuth and cut away the tube.

Okay, I can see some potential problems getting the channel features lined up with the bend axis and positioning the channel so as to get the exact radius you want.

You can also buy or make tooling that will bend thin wall channel directly, without the bismuth, within reason.

There's also the possibility of flanging a radiused blank, i.e. turning it into a channel after it's 'bent'. Or, if the bend goes the other way, you can apply metal shrinkers and stretchers to the flanges.




Mike Halloran
Pembroke Pines, FL, USA

 

[sairsk]

sairsk (Industrial) 25 Aug 05 8:29


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???

 

[MikeHalloran]

I'd use PVC pipe, but I wouldn't count on reusing it; just slice it with a hot soldering iron and throw it away.

But .08 inches is not a thin wall, unless the channel is fairly large. You haven't told us the channel dimensions or the bend radius or the bend angle or easy way or hard way.

Have you asked a toolmaker if he could make a bending die for the job? Do.





Mike Halloran
Pembroke Pines, FL, USA

 

[sairsk]

Mike,

The radius is pretty tight. I have to radius a 8 foot long channel to a 4 feet radius. Hence I need this encapsulation process.

 

[MikeHalloran]

That's not a tight radius unless the channel is quite large.

Could you possibly reveal the cross sectional dimensions of the channel, and tell us what plane you're bending it in?



Mike Halloran
Pembroke Pines, FL, USA

 

[sairsk]

Its a 2inch by 1 inch channel being bent the Hard way. The best thing to imagine this is like a U shaped ( endes squared) 2 inches wide X 1 inch tall being bent the hard way or on the edge.

 

[MikeHalloran]

I've met old-timers who could make that bend with a hammer.

Of course, now they're gone, and I'm the old-timer, and my hammer work is not that good. But you should be able to make that bend with mechanical tooling, without the added complexity of encapsulating it.

It's a little deep, but I think you could also Hydroform it, already bent, with simple tooling.

Are there other factors that might help you choose a process? Particular tolerances? Corner radius? Tangent ends? Holes? Slots?







Mike Halloran
Pembroke Pines, FL, USA