I have a 60 ton, 2 cylinder hydraulic forging press (you might have seen it on YouTube) and would love to have the control of a limit switch. Does anyone know what to buy and how to set one up?

Thanks in advance for any help.

Randy McDaniel

Edited October 9, 200916 yr by Randy

Maybe a little more information would help. What do you want the limit switch to do exactly.

Control the height or depth of the push. Instead of putting blocks in to stop the push at a certain point, using the limit switch to stop where I want it to stop.

I would mount a normally closed limit switch on an adjustable rod that would open as the rams came up to the point it was set to, stopping the pump motor. A normally open switch would be linked to the reverse foot lever so when the lever was fully depressed the pump motor would re-start and reverse the rams. The two limit switches would control a magnetic contactor/starter which you may already use on the motor.

You could use a pilot operated check valve, whereby you have a valve mounted somewhere on your press that is accuated by an adjustable length rod. This valve (normally closed) when opened allows hyd pressure to flow to the pilot operated valve which is in your main hyd lines going to the back of your pushing cylinders. Opening the pilot operated valve allows the oil to dump straight back to the oil reservoir.
There are other ways to limit stroke such as using wobbly plate variable stroke pumps controlled electronically as we have installed on our Davy press, but these sort of components cost in the $10000s/$100000s. The Davy works by having a sender unit in end of the hyd cylinder that senses where the piston head is and sends that info back to the control console which is all electronically actuated. The press speed and direction is controlled by the electrics varying the stroke and direction of the pump.

I saw a neat trick at a smith shop -- the guy was able to adjust hight of hyd cill so everytime it hit bottom it was in the same spot ! took the guess work right out of how far down into piece is it :)

Ironwolf you are leaving me hanging! What was the trick??? How'd he do it? That's what I'm looking for.

Thanks for the other replies, but I'm looking for more detailed info for someone who has no clue on how to do this and no idea what switches you are referring to or where to get them and how to hook them up. Sorry guys I'm a newbie when it comes to limit switches.

Randy,
Nice videos. How many GPM does your pump put out?

Pump: Nothern tool
16 gpm, 2 stage, 1/2" shaft
2,500 psi / max 3,000 psi

Thanks man.

Ok what he did was install a LG althread to the back side of Hyd cylinder so he can adjust where the cylinder was hight wise in the press frame @ the time he was bending rectangle tubes into an arch
form for gate project alittle @ a time and was able to get the same bend each and everytime does that help ?

PS after setting cylinder up you have to beable to lock cylinder back down to press frame so all the force is not on just the LG altheard behind the cylinder

So he's moving the cylinder mount in order to adjust the height? I would have had to planned that into the press from the get go. Maybe that will help someone. Back to the drawing board.

Yes He does, its set up for production so anyone running it can do the same thing again & again--no brain needed just go to the end of the cylinder stroke you're good next piece

Limit switches can be used, you'll need a solenoid valve to shift the hydraulics. Careful! Some solenoid valves just move a little plot valve and use hydraulic pressure to move the shuttle. That requires a certain back-pressure on the line so there is always pressure to operate the valve. They do make direct acting solenoid valves, however, and that would work better for you. You could put it in after your manual valve so that the press would act normal until it hit the limit switch. Then it would reverse until it hit another limit (up) switch that would send it back down. All the while you could stop it or reverse it manually. Probably need a couple of check valves to make it work with two valves, need to plot the different "states". Let me know when you get a little further along and we could do a schematic.

You will get some variation with differing resistance like size of billet and temperature of billet.

I can't imaging turning the pump off and on. I also don't think you would want to be "dead-ending" the cylinders either.

That's a pretty nice press you built. Where did you get the cylinders?

Edited October 16, 200916 yr by nakedanvil

Thanks, Grant. I'm starting to get a better picture of how this works. I didn't design or build my press, but bought it 90% finished and completed the build. He has 3 presses in his shop and just didn't finish this one. We have a company near here that buys out shops and businesses direct or through auctions, it's stuff is too good to call a junk or scrap yard. I guess they call it an industrial surplus and salvage company. Any way that's where the clyinders came from. He buys them there and then takes them to a hydraulics company to cut them to size and rebuild them.

Go with kunklers method less work and money.