Tube Crimping
Tube Crimping
(OP)
Not sure where to post this.
I am looking for manufacturing advice for crimping a tube with an internal end cap. The OD cannot dimensionally change more than +/-.002, and forming the crimp must not move the internal end cap more than +/-.005.
Tube: .450"OD with .030" wall thickness, 17-4 steel
Crimp: ~.090" wide with .414"OD

I was told that roll crimping this feature may impart a twist on the OD of the tube, so I am looking to form this some other way. My concerns are that any method will deform the OD which is very critical. Internally we discussed that the tube could be crimped with a 2-part clamp about 50%, then rotated 90deg and then fully crimped to reduce deformation.
Looking for any advice or suggestions.
I am looking for manufacturing advice for crimping a tube with an internal end cap. The OD cannot dimensionally change more than +/-.002, and forming the crimp must not move the internal end cap more than +/-.005.
Tube: .450"OD with .030" wall thickness, 17-4 steel
Crimp: ~.090" wide with .414"OD

I was told that roll crimping this feature may impart a twist on the OD of the tube, so I am looking to form this some other way. My concerns are that any method will deform the OD which is very critical. Internally we discussed that the tube could be crimped with a 2-part clamp about 50%, then rotated 90deg and then fully crimped to reduce deformation.
Looking for any advice or suggestions.
"Art without engineering is dreaming; Engineering without art is calculating."
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RE: Tube Crimping
RE: Tube Crimping
The connection must hold ~19kpsi internal pressure, which as described above, does the job.
"Art without engineering is dreaming; Engineering without art is calculating."
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RE: Tube Crimping
http://www.h-htube.com/endforming.html
http://www.airmo.com/endforming/hand.htm
RE: Tube Crimping
Heckler![[americanflag] americanflag](https://www.tipmaster.com/images/americanflag.gif)
Sr. Mechanical Engineer
SWx 2007 SP 4.0 & Pro/E 2001
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This post contains no political overtones or undertones for that matter and in no way represents the poster's political agenda.
RE: Tube Crimping
"Art without engineering is dreaming; Engineering without art is calculating."
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RE: Tube Crimping
to form ends on thin wall tube and it worked exceptionally well.
We also uses the hydraulic expansion technology to expand a CS into an Al component.
RE: Tube Crimping
Of course, they're using 316, not 17-4, and
the wall is thinner, and
the operating pressure is <250psi.
That's an ambitious design.
Mike Halloran
Pembroke Pines, FL, USA
RE: Tube Crimping
Ted
RE: Tube Crimping
http://www.magneform.com/apps.html
RE: Tube Crimping
"Art without engineering is dreaming; Engineering without art is calculating."
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RE: Tube Crimping
If a commercial process isn't available, we are thinking about making our own tooling. We are leaning towards a 3-jawed chuck that can be hydraulically clamped around the OD to from the crimp. Can anyone offer any advice/experiences towards this method in regards to OD deformation? If roll forming is a viable option, what deformation concerns should I consider?
"Art without engineering is dreaming; Engineering without art is calculating."
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RE: Tube Crimping
http://www.flowformingplus.com/?src=O
Ted
RE: Tube Crimping
I worked on one that was used to squash aluminium rings, there were no hiccups that I can remember, but it was a much more compliant system than yours. Since yours is not using the swage for sealing then a collet chuck (which leaves slight witness marks) will be fine.
Cheers
Greg Locock
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RE: Tube Crimping
RE: Tube Crimping
Not sure whether this is suitable for your application, but you may want to check out:
http://www.avdel-global.com/avsealii.asp
RE: Tube Crimping
Gtracer2, we had considered this early on, but were worried about stress concentrations at the counterbored shoulder. This v-crimp almost triples the amount of material in shear.
"Art without engineering is dreaming; Engineering without art is calculating."
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RE: Tube Crimping
Basically a shotgun shell (different filling) made of extruded aluminium with an aluminium end cap.
The cap was pushed in (up against an internal cardboard liner to make sure it didnt' go too far) and then the ends swaged.
It wasn't quite the same as your image though. The end was reduced in diameter slightly.
KENAT, probably the least qualified checker you'll ever meet...
RE: Tube Crimping
-b
RE: Tube Crimping
http://www.avdel-global.com/avsealii.asp "
Toward the bottom of the page it says
" Automotive low pressure applications "
RE: Tube Crimping
Bvanhiel, we are worried about post-assembly machining because there may be a risk of ignition since this assembly contains explosives. We've designed a 3-jaw crimping tool, we should have a working tool late next week. We'll see how that goes.
"Art without engineering is dreaming; Engineering without art is calculating."
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RE: Tube Crimping
It's the .002 deformation requirement that's a bugger. If the 3-jaw chuck idea gives warping/wrinkling of the o.d. beyond the .002 limit, you may need to try making a 2-stage crimp (first bump goes halfway, and you bump the part multiple times around the o.d., 2nd bump is basically the full crimp jaws you already have).
I like the idea of roll forming better, but with the ability to adjust and slowly advance the rolls until the crimp is fully formed. That should minimize the torque on the tube, especially if it's gripped correctly, and the speed of advance of the rolls should allow forming the part with minimal distortion/buckling of the tube walls.
Course, that's much more expensive too...
RE: Tube Crimping
I put Dgowan's comment and the link in quotes.
My addition was the low pressure rating as described on the website.
I reckoned your 19kpsi requirement is a bit above " a low pressure automotive application."
RE: Tube Crimping
I don't want to start a nit-picking contest, but the section of the website that contains the line you quoted lists both thin wall and high pressure applications as possible applications.
RE: Tube Crimping
Mike Halloran
Pembroke Pines, FL, USA
RE: Tube Crimping
"Art without engineering is dreaming; Engineering without art is calculating."
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RE: Tube Crimping
Cheers
Greg Locock
Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Tube Crimping
I've heard (from a manager, not an engineer) that they crimp right on the end of the tube for some important reason that I can't remember.
Tom
RE: Tube Crimping
This site shows one pattern for a crimp.
http://w
These people make all types of crimping equipment.
http://www.customcrimp.com/
RE: Tube Crimping
It's been a few weeks, I still do not have all of the parts received for our custom crimper, but I am informed it should be no more than 8 working days. If the crimp holds during testing, then we'll need a production crimper, and I think that CustomCrimp may be the ticket.
"Art without engineering is dreaming; Engineering without art is calculating."
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