Tight Bend Radius on Copper Pipe

What's wrong with fitting a proprietary 22mm solder elbow?

well its what the customer requires, he wants a lot off for peanuts, cheap peanuts at that apparently we had a sample with that radius on so it can be done but we cant find out how and who did it

Contact a refrigeration tubing vendor. Make sure they do "tight radius refrigeration" bends. You're right at the limit, but you should be able to get that pretty consistently.

You'll need to anneal the pipe I expect.
Quote a price using soldered fittings, and about 10 times the cost for the annealed and bent version. Hopefully the custome will chose the sensible version, or if not, you'll make a decent proffit.
Del

Del is right.

Aneealed pipe, with some effort and proper mandrel you should be just able to bend this radiau, For copper that may not me much difficult (normal radius should by 2.5 times minimum, but now you are on fractionally less 50/22 = 2.27)

Get hold of the proper mandrel and bender. If possible fill the tube with sand or some other suitable packing to avoid the flattening. Check that no kink appears.

In case of low quantity requirements, better ask somebody to bend for you, If a bulk requirement is there, swagelok or others will provide you with benders.

couple the bend and switch to soft copper tubing and do the bending by hand.

This could be possible, though it may depend on copper tube stock not being tempered too hard. Find or manufacture an inside-radius die to support the geometry of your desired bend. Prior to bending, pack the copper tube with sand, to keep it from collapsing as you bend it. Be aware that the wall thickness will decrease along the outside radius of the bend; therefore take care that it will still be sufficient to withstand the pressure that will be applied. After bending, clean out the sand.

There are also bending systems that insert a sphere to match the inside diameter of the tube (or pipe), and pull this inside sphere along as the bend is formed. You may need to do some research as to what capabilities are available locally, but I think you should be able to find a successful method.

It's doable, you'll need inner radius support, and pack it. Only seal at one end though as if it's too tight it'll actually flatten out and ovalise across the bend. Having it open allows the sand to move so it won't stretch, we haven't previously annealed it as such but low heat induced into the material intermittently during bending seemed to help prevent crimping on the inner surface. You will end up with some evidence of stretching on the outer side.

I've tried mandrel bending 42x3 cu on a multi $$$ machine we have and even when saturated with oil it still grabs and marks the tube, creates inner crimping and noticable outer stretching. There is a mandrel available that has outer rollers rather than just a sliding surface (tuboform I think is the supplier) this may aleviate the issue but I wasn't spending 2K on a mandrel to find out.

Thank you for all your input its been a big help,one other thing is would it be possible to bend the pipe in a fly press as apposed to using a dedicated pipe bender?This is an option we was considering , by having a top and die tool made with the desired radius and shaped to the correct diameter.Just wondering if this might squish the pipe or would sand or annealing help the forming process.

http://www.bendalloy.co.uk/

Consider looking into how horn (musical) instruments are made.

I've seen were they make a rough bend, place the part in a mandrel, then push lubricated round shot through the tube to to refine and restore the tubular shape.

Good Luck!

Your radius may beimpossibly small, but I have had best success in bending thin wall tubing using a long spring that is just large enough to fit over the tubing. This spreads the bending force evenly, allowing a rather sharp curve.

Heat softening may aid your project.

Fill the tubing with soapy water mixture and freeze it. then bend it accordingly and then let it thaw out and bingo you got it made. The water holds the shape of the tubing and the soap in the water lets the frozen water slid in the tubing. makes for a nice radius bend.

happy trails

GA.

This is how tailpipe manufacturers bend dual wall tubing. I've used it (the tubing) before. It should work with single wall, too.

Fill the pipe with sand and heat it up with a torch when it is red hot bend it around a wooden jig with desired radius.

This should help.

Textech

Your radius is in excess of twice the diameter. This is more than possible. In fact bend rads of 1.5 and 1 times diameter are done every day.

This is typically achieved using a standard mandrel, ball mandrel or cycling a chain of ball mandrels.

There are the more complicated extrusion bending or even hydroforming that you can look at but the tooling is very expensive.

Collapse of the copper is a big issue. This is where annealing may be more of a problem than a solution.

If you could post a picture or sketch of the configuration you are looking at it may be easier to suggest a solution. Also let us know what quantities or costing targets.

Another thing is if you do use sand or any other media that can be wet out, make sure it's dry or vented. I've seen more than one tube explode when packed with wet media and sealed then heated.

Guys,

Many, many year ago in our first house, no central heating, very little money.

A group of us bought a lorry load of antennae cable - about 22mmm, about being the operative word. It was fractionally bigger!! This was a very soft copper and bent beautifully in all of the 10 houses that participated - almost no need for the bend springs which did come out very easily after the event. At this remove I cannot tell you what bend radii we produced, every house had a different requirement.

The antennae cable was all scrap and the lorry load cost us One Pound sterling - 1963.

The only down side was that the ends were just not quite the right size so we made up a drift and drifted each end to get to the right size for compression joints. I know that if I was doing a critical job such as proposed here, I would at least consider using antennae cable!!

And we did remember to remove the inner!!

Good Luck.

Sleepy

You can anneal the tube if it is the hard type L or M tube and then pack it with damp sand and get a bend that tight.The packed sand will help prevent flattening the tube in the bend radius. I am sure you probably want a faster method for this though. You can buy copper tube in the annealed state and save some of the trouble by eliminating one step and know that it has been uniformly annealed throughout to a softer material. Although I have never personally tied it the pre-annealed tube might cold bend pretty good if you pack it with damp sand.

My name is Carl Inboden Ive been bending pipe over 25 years and have much experience with copper. First you need conventional bend tooling. bending die clamp pressure 1-2 ball mandrel maybe a wiper die. to keep from breaking anneal bend erea plus 1" on each side durind anneal process cap each end filling with nitrogen pop small holes in one end so you have steadt stream as this will eliminate oxidation after annealead let cool and bend.

my email is carl63@comcast.net Ive been doing this a long time if you have any other questions