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Heron's Aeolipile
sbwhart:
Hi Ralph I,m Stew John spoke about me
I'll try and help you round your pressing problem (pun) :D
:- 1 You have the die in the top mounted in a top pressure plate (fixed) that's bigger than the sheet you are trying to form
:- 2 The punch is in the bottom with a spring loaded preshure plate around it, the plate is slightly proud of the punch.
:- 3 The blank should be bigger than you realy need so that when the press is bottomed out, some of the sheet is still being nipped by the preshure plate.
:- 4 When the load is taken off the preshure plate stripps the work off the punch.
You need nice big rads on corners and lubrication on the sheet, try washing up liquid, swafega, WD40.
What your trying to do is restrict the plate just engough to make it iron its way into the die
You could use rubber for the springs Doggy rubber balls cut up (poor Doggy) :(
Problems you may encounter is the strip bursting this is usualy due to trying to form too much at one go, or to much pressure from the pressure plate, or the sheet may need anealing, you may have to do a partial form, before doing a finished form.
I've attached a sketch showing methodology for the tooling
Another option if you could get hold of a thick enough piece of rubber to use as the die, I did this for a city and guilds project:- made shallow ash trays.
How about replacing the punch with a rubber ball (just thought of that one) :thumbup:
If your toggle press hasn't got enough humph I've got a fly press you could use
If you need to chat it over John knows how to contact me
Good luck
Stew
:D
Circlip:
Hmm, Stew has reiterated three basic points from post 38 Ralph, Radii, annealing and lubrication. Yer NOT going to be able to do it in one bonk, and rather than trying to "Coin" the ball halves, a ring die might be more appropriate, and yes,the propper way to form this shape in industry would involve pressure and stripper plates and while you're building it all up, don't forget the open and closed height of the press (yes I did Stew, but only once).
If you look at any of the BOOK descriptions on how to make toy boilers, annealing regularly is the key and this applies if you're going to try to spin it too. Can't remember if you've had a go at panel beating yet Ralph but it's certainly worth getting a piece of copper, annealing it and having a bash over a simple form just to see how long it takes to become too hard to work. Don't forget, rather than dash out buying a sheet of virgin Copper, a bit of old 50mm (OK for our pals over the pond 2") water or gas pipe flattens out to 150mm ( 6" ). Same rules apply to Brass re annealing but Brass seems to harden up quicker and you soon get the "Feel", soft metals "thud" while harder ones "ring".
A few more bits to think about and watch yer fingers in that press. Hope Boggy issued you with an instruction sheet with it ( and it will be in English, might even be OLD English )and a CE cert ? ? :)
Regards Ian.
PS. Just for the record, cartridge cases used to be made from -------Cartridge Brass.
sbwhart:
Hi Ian
Like your comment re shut height:- once saw a 2 1/2 Ton Taylor and Challen press, that had the main crank shaft bearing smashed off, (lovely cast iron Johns probibly got bits of it in his material box) when the setter failed to wind the pitman back after a tool change, he didn't do it again, 5 days suspension without pay.
:(
Catridge brass is 70% copper 30% zinc for thise who are interested.
Have fun
:wave:
Stew
Divided he ad:
Ok... So there's a lot to reply to and talk about here!
Here goes....
Darren, I don't really want to heat the die... It is only ali and I am not sure if it would weaken it in anyway? I could always leave the blank warm before pressing? Don't know if that would be a bad thing? (suggestions?)
Peter, I see what you mean... It makes a lot of sense to do it in stages.... I might have to make some more punches!!! Thin more difficult that thicker... Poss due to the stretch factor?... All things to consider!!
Hi Stew, welcome to my fun project :D and MadModder too :mmr:
To start with the techy stuff.... I think I have a view of how things were/are done. I drew a crap o cad for you to view... Hopefully it is clear enough... I wonder if this would work?
I don't think I have the time/patience/abillity to make a press the type shown/described... Not too sure about the rubber ball thing either... Wouldn't the pressure split the ball ?
I understand the need for a greater radius on the lip of the die... This will be done (I know you told me Ian... But I thought a smaller radius can always be made larger... You know the rest of that saying!!)
The chat idea sounds like it could be fun Stew... We will have to see about it next time I get over to Crewe :thumbup:
Ian,
I am about to trawl the interweb for all the info I can find on the subject of press forming and then plan to spend most of the afternoon trying to understand it all. (this could be interesting for a person with litereature induced narcolepsy.... For some reason I fall asleep when reading a page or so?)
Still I am going to give it a good go!
I'll also try to find some copper pipe... Bit hard top come by these days, everyone is selling it to scrappy's.
The cartridge brass might also be a bit of fun to find.... I'll give it all a go.... Might also try to find some about 0.25mm thick... Make it easier on myself! (possibly, see answer from Peter)
"Thud" and "ring".... Got it!
I took some time adjusting the press... Instruction was given on all that, I also have no intention on putting my hands near the business end!!
Fun.... Yes it is all fun... If it becomes no fun the project will become shelved until I decide it can be fun again :D (No point in doing something you don't like doing ehh!!?)
Thank you for all the great responses Guys, I'll be putting the suggestions to work and see where we get to :dremel: :thumbup:
Ralph.
bogstandard:
Thanks for coming to the rescue Stew, even I now know what is required.
Ralph, as far as I can ascertain, the metal isn't clamped around the top edge, just restrained (hence the spring loading), allowing it to flow down into the die as the punch pushes the metal down into it, and the punch pulls it into the die as required. You are not trying to stretch the metal, just making sure that no excess is allowed into the die, unlike your first brass pressing with the fold on the side.
I am more up on the punching of materials rather than press forming, and certainly know the damage a press brake or hydraulic press can do. Somewhere in my workshop I have some slugs of material, 1/2" diameter by 1/2" long that were punched out of submarine bulkheads, the material was too difficult to drill, it work hardened almost instantly. I still haven't found a use for them.
In fact the toggle press that Ralph has now, was used to punch 1/8" copper/composite laminated materials for use in an industrial lapping process, and I cut many thousands of pre shaped holes with it during the trials.
Getting back to the materials now. In the thickness that is being envisaged to be used, approx 0.5mm copper. That should be able to be formed in one pressing after first being well annealed. I think brass would be a struggle for the depth of mechanical pressing before it work hardened, the press just wouldn't be able to impart enough pressure and speed before it got to it's work hardened state, but I have no doubts about the copper being able to be deformed to that depth in one go. On the other hand, Stews' flypress would have no trouble giving brass the pressure it needed.
I suppose people are thinking, why go to all this trouble for a pair of half spheres. Not only is Ralph and other people learning a lot from this exercise. If it was wanted, once the technique is perfected, many thousands more little half spheres of all shapes and sizes could be made. Also it is things that are learned along the journey that can help with other projects that might arise. Even if it ends up as a failure to go down this route, look at all the other processes Ralph has learned about getting there. So nothing is ever a true failure, how many did it take Edison before he perfected his light bulb, but he sure learned a lot on the way.
I suppose this could have been a guaranteed success if a lot more research had been done, because these processes have been around a lot longer than we have, but the fun of it all is doing it from scratch and getting other people involved.
This all started with Ralph making a little ball turner for his lathe. It shows just how things soon progress.
Whatever next?
John
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