Internal water pressure expansion of metal

[eat]

hi I had some great links on applying water pressure inside
of welded sheet metal parts to expand them like a balloon of metal
One guy made a exhaust pipe for his motorcycle
Another woman was making pillows looked real but where metal
There was a link that said how to do this
And I can’t find the information on my computer anymore
And I have a little project in mind that this would be the best method for
I know you are not supposed to post some links but if someone could let me know something if they have the information like search words I cant find it and I know it was something simple like welding the metal
Then hooking a hand pump to it and pumping it up like a balloon
Thanks I know its here on my computer in this 20 gigs somewhere
But no search worked yet or on the internet help please thanks

I believe this is the right forum as it bends the metal

[ViperTX]

Well off the bat....the water pressure required to deform metal is probably beyond your capabilities.....geesch just think of the safety issues.....I seriously doubt that a hand pump will do anything more then give you a workout.....now add a bit of heat....yeehaaaa....we have a boilermaker.......

[WhiteTiger]

I believe the term is hydroforming. Most of the apps for it that I know of though use either explosives or submerged arc to generate a shock wave that forms the metal against a shell mold.


Tiger

[eat]

Yes possibly I was not remembering it right
I found one link to the pillow artist
www.calsmith.org/news2.html
There is a pillow on the bottom and they say
Inflated with air I wish I could find the place with the guy that made his motorcycle exhaust he explained it all very well how he did it from the welding to the finished product and the pump he used how there was not much risk involved for a small volume
My memory is not that great but
I know there is a way to make what I have in mind
I have seen it pretty straight forward without spending forever
I think you weld it inflate it hammer it just a little then cut off what you don’t use he made a
Tapered pipe that came out nice then he welded a mounting bracket on it
I will keep looking but have been at it for hours it is driving me nuts
I think I got it on rec craft metal working news group
Just thought someone might know what I was looking for

[Geof]

Originally Posted by WhiteTiger I believe the term is hydroforming. Most of the apps for it that I know of though use either explosives or submerged arc to generate a shock wave that forms the metal against a shell mold.Tiger

Yes it is hydroforming and what WhiteTiger is referring to is, I think, called explosive forming. Hydroforming is used for making chassis side rails by Magna International, one of the larger auto-parts subcontractors. A steel tube is put inside a mold and inflated. Much the same as blow molding plastic but at a much higher pressure.

Regarding inflating it with air I suppose it is possible if you are completely out of your mind.

[martinw]

Some manufacturers of solar water heating panels use the water pressure technique to form the waterways in stainless steel sheet. They weld lines to join two sheets together then use water pressure to 'blow' the non-welded areas apart.

Martin

[pauluk]

Hi All
Just a couple of points, don't be tempted pump it up with air, if you do and a weld fails, it will be like a bomb gong off. If you use water it is safe, because as soon as you get leakage the pressure plummets. Because water is incompressible there is virtually no stored energy to dissipate. For the same reason it is easy to create and maintain high pressures since you only need to be able to pump small volumes. If you use a small bore (say 3/8” bore) hand pump you should be able to create 300/400 psi without any problem

[NC Cams]

Hey guys: 300-400 psi is dangerous in a pressurized vessul whether you're using water, air or duck feathers.

Even A pin hole leak with that much pressure behind it could LITERALLY cut you in half... if it doesn't erode and explosively try to exit through same leak point...

Explosive forming is NOT the same as hydroforming. I've seen hydroforming of tubes and other products for automotive use and they use hydraulic oils applied by massive pumps for the pressure mediums. The parts are in closed dies when formed - they're NOT laying there and swelling like balloons or inner tubes.

Keep in mind that you are deforming to YIELD and unless you "guide" the part into forming the way you want, the expansion will occur randomly and usually with quite a bit of uncontrollable randomness - IE: explosion.

Hydroforming is NOT something that should be played. The forces involved can be LETHAL if they get out of control. Half baked, half finished, half fast attempts at duplicating the process improperly are QUITE ILL ADVISED. They could be your LAST project.... literally.

Working with hydraulic assist is a proven method for doing many things. It can be deadly serious. Hydroforming is NOT something to be casually attempted. Saw a guy try to do something like it only with grease gun for pressure - hose ruptured and shot a wad of grease into his hand/arm. Lost both due to mandatory amputation 'cause they couldn't get the grease out...

A lot of the process involves proprietary techniques and/or equipment. Although the concept is simple enough (blow molding only with much more OOMPH), I'd hardly think that the true "secrets" associated with the process would be readily "findable" as a freebie on the internet.

Be REALLY REALLY careful if you try it - you have been warned....

[carlnpa]

I am familiar with hydraulic forming of metal parts using process like in link
www.bonnydoonengineering.com
HTH
Carl

[Geof]

Originally Posted by pauluk Hi All Just a couple of points, don't be tempted pump it up with air, if you do and a weld fails, it will be like a bomb gong off. If you use water it is safe, because as soon as you get leakage the pressure plummets. Because water is incompressible there is virtually no stored energy to dissipate. For the same reason it is easy to create and maintain high pressures since you only need to be able to pump small volumes. If you use a small bore (say 3/8” bore) hand pump you should be able to create 300/400 psi without any problem

Pauluk; When you get to the pressures needed for hydroforming water is compressible. I think the number is something like 12% volume reduction at 25,000 psi. You will need a very sophisticated hand pump to get to this pressure region of course.

For inflating stainless steel solar collectors or metal pillows probably between 1000 and 4000 psi would do and a well made hand pump could get to this quite easily. I used to test acrylic filter housings to 2500 psi with water using a home made pump.

Although inflating something the volume of a pillow could be tedious; my pump discharged about 0.2cubic cm per stroke; how many liters in a pillow?

[HPbyGD]

One of the sites that has some info about hydroforming exhaust pipe is at eurospares. If you can't find it with google let me know and I'll try and find the link. I have done some motorcycle expansion chambers and it is fun to watch the pipe form as you pump it up. I borrowed the plumber's pump from the guy that has the eurospares web site. It took about 100 psi to form the 20 guage sheet metal.
Gary

[eat]

HPbyGD thank you so much with your info that sounded familiar
I was able to track down the site
http://www.eurospares.com/frame8.htm
You guys should see this look at the article and check the pictures very interesting for some applications
Hope it works for what I have planned
Would sure save me a lot of work thanks again