Making tube with changing diameter along the length 10

[sftvbr]

I have to make a tube with a variating diamtere from 45 to 60 mm. the thickness is 1mm. the length is 40 mm also and the diameter change happens like a 90 degree step in the middle of the length. The material is stainless steel

As far as I searched , there are two manufacturing methods, one is reducing the diameter from 60 to 45 mm (like tapering ) . the other is increasing the diameter from 45 to 60. My guess is the second one breaks and won't resist the deformation.

what suggestions do you have for evaluation and choosing between the methods ?

 

[tygerdawg]

I suggest you start with specifying design parameters: purpose of part, applied loads it must survive in service (tensile, compressive, bending, torsion), and the material (and any treatments) required for the application. Then investigate spin forming or flow forming processes.

TygerDawg
Blue Technik LLC
Virtuoso Robotics Engineering

http://www.bluetechnik.com

 

[Tmoose]

Do you have any particular material in mind ?

Are there any tolerances on the 45 mm and 60 mm Øs, either ID or OD ?

https://www.amazon.com/Walker-41888-Exhaust-Pipe-Reducer/dp/B01LRH84JI

" I have to make a tube.. " .
Is the quantity one, and only one ?

If it is you making this tube, what tools do you have available?

https://www.youtube.com/watch?v=wOpt0iL9_8w

5 down, ?? to go.

 

[sftvbr]

Thank you for the points, the material is stainless steel, I edited my question as well. the diameters are both External.

there are no severe loads in the application, only the deformation of the part is concerned

 

[MintJulep]

what suggestions do you have for evaluation and choosing between the methods ?

I suggest that you choose the one that allows you to achieve your undefined requirements.

Alternately, you could think about 3 parts.

 

[btrueblood]

Or 5 parts and one "tool" - 3 pieces of tube, two washers, and a Tig welder.

If you are forming tubing, stretching/expanding is easier in some ways than shrinking. Both should be done on annealed stock, and both processes will require multiple in-process anneals to keep from cracking the material. Shrinking requires that the material increase in thickness, or buckle/wrinkle. Usually the latter happens, and it is tough to control if/when it does.

 

[EdStainless]

What equipment do you have?
You could layout the projection and then roll the piece and make a longitudinal weld.
Or you could just use a press and expand one end using form tool and lots of lube.
With this much stretch you will need an intermediate anneal.
If you wanted to do more work but less heat treat you could use 50mm starting stock and stretch one end and shrink the other (with a ring die).

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[handleman]

Hey, nobody's mentioned it yet... You could just machine it out of a billet.

 

[sftvbr]

I want to thank all of you guys. sorry for the late reply. I can not talk about the application, but what I can say is that it should be one part , and maybe machining it out of a billet would be costly, in terms of material and time.

Thank you for the points on shrinking

 

[Compositepro]

Try metal spinning.

https://www.youtube.com/watch?v=RB1RwNUj2o8

 

[Lou Scannon]

Not directly applicable perhaps, but you might research how traditional steel bicycle forks are manufactured.

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

 

[3DDave]

Making it out of billet is cheap. It will 100% work, doesn't require any special setup. It's the sort of thing home-hobbyists can do.

 

[sftvbr]

@hemi : do you have any link or something about that ? I did not find any

@3DDave : Thank you Dave, well in industrial scale, the material discard rate should remain at 5% , I feel that's a lot of material to throw away if I start from a billet

 

[3DDave]

Where else have you seen parts made that look like this:

This is to scale proportion, to save others from spending 10 or 20 minutes seeing exactly what is required, based on the description so far.

Forming tech will make major changes to the wall thickness.

(Still have 15 out of 20 questions remaining.)

 

[IFRs]

Machine it out of pipe with the appropriate ID and OD - less waste than billet...

 

[BrianE22]

Do you have to have the 90 degree transition? If you can live with a taper then swaging might work.

 

[handleman]

When you say, "One part", if you mean that you only need qty 1 ever, then 100% machining from billet is the only thing that makes sense. All the time you will spend trying to figure out some other way to make it will cost way more than just making a drawing and sending it to a machine shop.

Now, if you mean that it has to be one piece, and it needs that shape, and you're going to make thousands of them, deep drawing should probably be on your list of things to investigate.

 

[Lou Scannon]

Never mind,

Thanks to 3DDave, I now understand the geometry. No similarity to a bicycle fork.

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

 

[GregLocock]

3DDave has chosen the most horrible interpretation of the OP's desired geometry, probably deliberately. Here's one that my expert draftie knocked up that could be made much more reliably in any quantity.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[chicopee]

I would find a tube of the same OD and of the same smaller ID of the shape shown by 3DDave and machine the inside to the same large diameter shown in the same drawing. to the desired depth.