Need help understanding the pressure

[Fe-Wood]

I'm in need of a hydraulic press and for $$$ reasons, I need to build it. The few I've seen at auction are used up junk with a high price.

So, I get the basic concept that ram Dia. and PSI = force and that GPM = faster cycle times. What I need help with is understanding where is the sweet spot is. Is it better to have a 11GPM @3000 RPM pump coupled to a 1750 RPM motor or a 3450 RPM motor. There are so many variables.

I would like a press that moves reasonably fast and can deliver good force, about 50 tons. I also want to be able to use the power supply for a "porta power" type set up on a jig table. But thats more of a plumbing issue for later.

In short, I'm looking for information on a "H" frame with a 12 to 16" throw ram. I also need help with online suppliers.

Thanks guys!

[rthibeau]

Here is a link to the thread on the press I recently built.... http://www.iforgeiron.com/forum/f82/another-hydraulic-forging-press-15486/ John Larson made a good post about the rpms and pressures. In essence, the higher 3450 rpm motor will get you the 11 gpm @ 2500 psi and the 1750 rpm motor will get you 5.5 gpm with the same pump. If it is for general blacksmith work, I think a 24 ton press is plenty which would be a 11 gpm pump, 5.5" dual action cylinder, and 5 hp 3450 rpm motor. The cylinder I used is a 10" throw and it could have been shorter. All the hydraulics and motor I got online from Northern Tools, they seemed to have the best overall prices. Oh, and Jim Batson's manual on presses although pricey was a very good reference source.

Edited December 7, 2009 by rthibeau
added text

[monstermetal]

One thing you need to figure out is what you primarily want to do. A press that is built to forge with is not well suited for most other things. If you want a "shop" press you need tonnage and slow speed, and ram guides are not important... If you want to forge with it you speed is more important than tonnage... If you can only take one bite before the dies suck out all the heat its not an effective way to forge.. and it is really important that there are some kind of good guides to control the die position

You said you want to use a porta power pump.... which is 10,000 psi for most systems.... They give alot of tonnage for a small cylinder but they are not designed to work all day and they are slow when you get into the bigger tonnage cylinders... and they are much more expensive than 3000psi systems...

as for the sweet spot.... for forging I think you would find with about a 4"-5" cylinder with a pump that will do 8-13 gal/ min is where you want to be I think you will also find that most of the time you will never get over 1500 PSI when forging unless you are doing a real deep detail on something.. many two speed pumps will move that kind of oil with a 5HP motor at 3450 but when you get past like 300psi (any load) they kick down to like 2 or 3 gpm... which is fine.. its the dead stroke that causes problems to get that flow with a single speed pump your going to need 10-15 HP

[Fe-Wood]

Thanks for the information and links!
Richard I did look at your build thread, nice press by the way. Why do you feel you could have used a shorter throw? To long between cycle times? Flex?

Monster- I don't want to use a "porta power" pump, I want to use a portable ram hooked to the press pump for bending on a jig table.

I am looking to use it for forging hot and pressing relief forms in copper. I am particularly interested in using it for slitting and drifting. Is this crazy? I don't have a lot of experience with this kind of pressing...

Is it nuts to think about 2 or 3 cylinders run from the same pump and motor with quick couple disconnects?

[rthibeau]

How you make your dies and build the frame dictates the length of stroke you can effectively use. I got a 10" stroke cylinder and built figuring to have 10" between dies to accommodate tooling, stock, etc. I think that is too much, an 8" stroke cylinder would be fine and build to have less than that much between finished dies. That gives room for 2 - 3 inches of stock and up to 5 inches for tooling in addition to the size of the dies. Too long a stroke creates flex in the ram. With a dual action cylinder, you control both up and down ram movement and use only the space necessary for the stock anyways, so speed isn't a factor as it will move only an inch or so while pressing, the rest of the stroke capacity is unused. The only problem with slitting and drifting is getting the dies/tooling to line up exactly so you get accurate holes.....any slop there and you get slanted or off center holes. A flypress is easier for that work. I'll rebuild the top part of the frame to shorten up the distance between dies. As for the extra cylinders off one pump...a manifold system could be setup, I don't know about hydraulic quick disconnects.

[Fe-Wood]

Thanks Richard-
At this point I'm thinking about a multi ram press for different applications. An H frame and a half? I will need a platen about 12"x16" for the copper and tooling ram for forging. A manifold is a good idea to ponder, thanks for mentioning that!. I use the disconnects on heavy equipment, they are sorta like air hose couplers but for hydraulics. So many different possibilities I hadn't considered.

[Fe-Wood]

Reviving the thread-
Hay I have landed on a press design that may work for me and I would like some inputs.
Potential uses include-
Drifting with hand held tooling, Shouldering with a guillotine, forming Mokume billets and sheets, embossing sheet stock and bending bar stock with jigs and fixtures.

Heres my concept:) I'm sure its not new.... but I haven't seen one either.

I kinda need an "H" frame and a "C" frame press for these operations. So, I was thinking of making an "H" frame with a "C" frame off one leg of the "H". I would run 2 different cylinders on one pump, one for each press. They would be independently controlled by 2 foot pedals.

Comments, ideas?

Thanks