wiring controls for a hydraulic press - opinion?

I can see the reasoning behind having a shop e-stop. I just don't think it works in all shops. If you have three machines, ok.

We have power presses and double column CNC mills in a shop a couple of football fields in size. It sounds like it would be tough to connect everything such that they would be safely shut down from those switches.

At certain points in the process of loading a die, the shut height in the press is less than the height of the die. I'm not sure how the brakes on those mechanical presses work but to have a ram fall at that point could cost tens of thousands in damage (and be very dangerous).

And then there's the issue with people accidentally hitting the e stops. When our dies are going for buyoff, people are pretty edgy as it is...

Regards,

Robin

Grant, Even tho you are not inclined to "monkey" with the plumbing - I personally would prefer to have a start/stop button for the motor, so when you start it, it runs and stays running until you are done using the press, when you would shut the motor off. I would plumb in an open-center valve and set it up so that pulling down on the handle will press down and lifting up on the handle will return the ram. If you get a spring-loaded to center-position valve it would give you a great deal of control and you could incorporate a pressure gauge on the ram so you know what kind of forces you are dealing with. Just my personal opinion..... Ken.

I got this press running. First thing I did was put my 6000# load cell under the ram and tried to ease it down onto it. Well, it instantly maxed out that load cell, probably broke it, don't know yet. So then I just put a solid block of steel under it and ran it down to see if the ton gauge works. The motor stalled when it got to about 25 tons. This makes sense to me because I'm just using a temporary lashup for the motor power wiring, which involves big alligator clips. This is fine for spinning up a motor without a load, but with a big load I don't think it's passing all the current. Anyway, I have learned enough to know that running a press this big is going to involve getting a little close and then going "bump" .. "bump" .. "bump". I don't think you'd have the control you needed with a start/stop button. Right now I wired up the start button in series with the mag switch coil, so it acts like a momentary bump switch which is what I want. Obviously the press works fine. There are some things I'd like to be different about it but I'm not willing to spend any money on them. In fact, after a winter with this sitting outside under wraps, I don't really have a place for it. Anyone in the Pacific Northwest want a 60-ton hydraulic press cheap? How about $500. It weighs maybe 600-1000 pounds, and has all the features you'd want -- the circular handle which raises/lowers a ram extension, a ton gauge, a 3-hp motor (3 phase 440/220, currently set up for 220VAC), a winch/wire rope arrangement to raise/lower the table, and the dirt and grease come for free. I cut it down so it will roll into a standard garage door on my machinery skates, and I put on a Square D motor starter and a NOS button station, and replumbed the return line. I also added 3 new Gates belts and changed the hydraulic fluid. If you want this hummer go to

shoot me an email and we'll go from there. I don't want to ship it, that's how it got damaged in the first place.

Grant Erwin Kirkland, Washington

Ken Sterling wrote:

Now you're getting the idea. The fact is using the motor for control is like some posters said a little tough. There's always the inertia in the motor which takes it farther than you'd want. My press is similar to what you describe with a gigantic piston pump inside the reservoir. I've never managed to see the actual piston in the pump but the connecting rod is huge with a crank shaft that's larger than that in any auto engine (maybe a large tractor crankshaft comes close). The other side of the coin is valving for such a high pressure system is hard to come by. Most valves are rated for 3,000 psi with a few out there rated to 6,000. My press runs up to 6,000 fairly easily and can do more if pushed. I'm fairly certain that the valves on my press are home made (the rest of it darn sure is).

The trick to running a press like this is to never let your hand off the relief valve. Mine has a nice long handle on it which comes down near the switch. When it comes time for needing just that little bit more you have to turn on the switch long enough for the motor to do a coast through one pressure stroke. When the piece reaches the proper place you throw the relief valve to remove the pressure. It helps if the whole thing runs fairly slow to begin with (mine has a Ford model A transmission on it to allow different speeds, it's been in second gear ever time I've ever used it but I've heard of it being placed in first).

Sounds like a nice press. I suppose you could do like I am and keep it outside though up there that's harder to do with all the rain. Unfortunately it's way to far from here to even consider.

Wayne Cook Shamrock, TX

When Alpha testing (smoke test) NEVER use the good tools first go round.

Shrug

Been there, done that. Got the pieces.

Gunner

That rifle hanging on the wall of the working-class flat or labourer's cottage is the symbol of democracy. It is our job to see that it stays there. - George Orwell

Grant, Even tho you are not inclined to "monkey" with the plumbing - I personally would prefer to have a start/stop button for the motor, so when you start it, it runs and stays running until you are done using the press, when you would shut the motor off. I would plumb in an open-center valve and set it up so that pulling down on the handle will press down and lifting up on the handle will return the ram. If you get a spring-loaded to center-position valve it would give you a great deal of control and you could incorporate a pressure gauge on the ram so you know what kind of forces you are dealing with. Just my personal opinion..... Ken.

Grant, Even tho you are not inclined to "monkey" with the plumbing - I personally would prefer to have a start/stop button for the motor, so when you start it, it runs and stays running until you are done using the press, when you would shut the motor off. I would plumb in an open-center valve and set it up so that pulling down on the handle will press down and lifting up on the handle will return the ram. If you get a spring-loaded to center-position valve it would give you a great deal of control and you could incorporate a pressure gauge on the ram so you know what kind of forces you are dealing with. Just my personal opinion..... Ken.

Grant, how fast does the ram move? If it moves fast enough, you might try selling it to blacksmiths.

I have a hydraulic forging press that is really excellent to forge with. It uses a log splitter pump (two speed). It moves the ram at about

1" per second until the pressure builds up, then switches over to about 1/4" per second. Mine is 30 tons, which is plenty for general forging (20 is probably enough). I originally built it for 2" per second, which was *way* too fast for many operations.

So 1/4" per second is plenty fast for the actual forging, the trick is getting the ram to the work while it is still hot. Dies can be welded up mild steel since there isn't any impact, which is very convenient.

It tends to be a single stroke tool (which is all you need). By the time you're done with the first stroke, the work is too cool for a second. It works best on 1/2" and up for simlar reasons. A hydraulic forging press makes a blacksmith think about thick metal in an entirely different way.

Steve Smith

Grant Erw> I got this press running. First thing I did was put my 6000# load cell

Indeed.

Gunner

"At the core of liberalism is the spoiled child - miserable, as all spoiled children are, unsatisfied, demanding, ill-disciplined, despotic and useless. Liberalism is a philosphy of sniveling brats." -- P.J. O'Rourke

Grant, Even tho you are not inclined to "monkey" with the plumbing - I personally would prefer to have a start/stop button for the motor, so when you start it, it runs and stays running until you are done using the press, when you would shut the motor off. I would plumb in an open-center valve and set it up so that pulling down on the handle will press down and lifting up on the handle will return the ram. If you get a spring-loaded to center-position valve it would give you a great deal of control and you could incorporate a pressure gauge on the ram so you know what kind of forces you are dealing with. Just my personal opinion..... Ken.

Sorry about the repeat postings.... I was having trouble getting them to travel through cyberspace.... then all of a sudden, they all went... Ken.