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owen bush

control system for a cycling hydraulic press.

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Up until now I have used an analog spool valve to run my press. I have however been very impressed by some of the cycling hydraulic presses I have seen, that run like a power hammer using a microswitch for top of up stroke and a microswitch for bottom bottom of down or a pressure switch whichever kicks in first.

I love my press for punching but found it limiting for drawing out work, the limitation being my reaction time at top and bottom of stroke, which sucked into heat time and at the bottom of the stroke cooled the metal too quick.

My thoughts were that with tooling set close and a cycling control system the press would really become the tool it always wanted to be.

I had this idea about 3 years ago and bought a solenoid valve block and some relays and a pressure switch and micro switches and a foot pedal.....anyhow life took over and 3 years passed..... I am back on this idea.

At the time I had someone draw me up a circuit diagram. I think it makes sense again.

what I want is :-

Foot on pedal ram moves down, foot off of pedal ram lifts up until it hits top micro switch then stops.

If I keep the pedal down ram moves down until it hits bottom micro switch or reaches pressure , it then cycles up until it hits top switch and then down again and the cycle repeats until the pedal is depressed.

 

here is what I have :-

 

24502092606_08ac48a2ee_z.jpg

 

any thoughts or critique would be most welcome.

 

 

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it almost sounds like what you really want is a powered friction screw press. My dad is a recently retired electronics tech and hydraulics person and he's built a lot of machine automation stuff. Let me pass your diagram by him and see if he thinks that it'll do what you want, or if he knows of a simple way to do it.

 

I would of course love a friction screw press and its on my radar..... but this is a very different fish . I want to maximize the forging potential of the press and take out the human time lag that happens at the point of maximum material contact.

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Owen,

I think you are on the right track with the cycling concept.

Mixing the human controlling process with the electronic controlling ( lifting your foot and still having the system do something ) scares me. I have worked in an environment with lots of hydraulics and lots of micro switches/timers etc. Hydraulic power can be very dangerous when the controls get complicated.

I have a system set up ( not yet tested ) which works off of a foot switch and a hand switch . The hand switch turns the 3 position hydraulic valve off ( or on) causing it to seek a center position ( valve off) and all the fluid from the pressure source is cycled back to the tank.......my foot switch only has two positions open or closed.

When I turn the 3 position hydraulic valve on ( using the hand switch) the ram is moving up ( foot off the foot switch) or down ( foot down.

The foot switch causes the valve to pass by the central position which would allow the fluid to cycle to the tank.

All this should work at an appropriate ram speed , my speed may be a little too fast to manage it all ( the other concern right now is the possibility of hydraulic hammering at the rapid change of ram /fluid direction.

 

Jan

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I love the control of my Uncle Al's press.. It has a pretty simple design, but is very fast. I would be lost without the foot control !

I can just about "bump" it like a power hammer.
In combo with the many "stops I have made, it is giving me a very good range of things I can do with it. I want to try a number of new dies as well.

I have been a bit worried about the extra stress that my "bumping" may be causing though. ???


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Owen,

 

That is more of a logic diagram than a circuit diagram, although the differences are subtle. I'd say whoever drew that up for you programmed PLC's at one time or another.

 

One thing I see that may not be quite what you want is that the ram will always have to return to the top of stroke before you could get it to move down again. The up solenoid will be energized any time the down solenoid is off, and the top limit switch is open. However, you cannot energize the down solenoid until the up solenoid turns off.

 

If you want to reverse the direction of travel in mid stroke, you will need to alter the logic slightly.

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Owen, I am out of town right now, but when I get back to my shop, I will send you photos (and maybe even post a video) of my press controls and operation. I can get the contact info for you too, on the guy who makes these controllers. Being that you are out of the country, I might be able to persuade him to get you some shop drawings of how it goes together. The depth of press is set manually. You set the stop and there is a graduated adjustment that decreases (or increases depending on which way you turn it) the stoke by 1/8 inch per click. There is also a fine adjustment mechanism for minor depth changes. The up stroke is controlled either by time or distance (user controls). I have mine set for .7 seconds before it starts going back down. The controller is either a foot switch or a joy stick, either one works at any given time. For single time press operation to squish and hold, the depth controller is simply moved out of operation. The press will come down as long as you hold the switch and will stay there when you release. It will not rise until you reverse the switch. It may sound complicated, but it is very simple to use and understand.

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Owen, I am out of town right now, but when I get back to my shop, I will send you photos (and maybe even post a video) of my press controls and operation. I can get the contact info for you too, on the guy who makes these controllers. Being that you are out of the country, I might be able to persuade him to get you some shop drawings of how it goes together. The depth of press is set manually. You set the stop and there is a graduated adjustment that decreases (or increases depending on which way you turn it) the stoke by 1/8 inch per click. There is also a fine adjustment mechanism for minor depth changes. The up stroke is controlled either by time or distance (user controls). I have mine set for .7 seconds before it starts going back down. The controller is either a foot switch or a joy stick, either one works at any given time. For single time press operation to squish and hold, the depth controller is simply moved out of operation. The press will come down as long as you hold the switch and will stay there when you release. It will not rise until you reverse the switch. It may sound complicated, but it is very simple to use and understand.

 

do you have a vid at all of the press in action? sounds like a good control system.

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do you have a vid at all of the press in action? sounds like a good control system.

I do not at the current time. I got a Sony GoPro for my birthday last year and making the video has been on my to-do list. I just spoke with Jeremy (he makes these things) and he said he has a video he will send to me. I will try and post it when I get it, or make one when I get back to AZ.

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Can't speak to the controller set up, and maybe it's redundant, but the single best thing I did to address the heat sink in the dies was make a rack for them on top of the forge, and keep them hot when working, like at least several hundred degrees.

 

I do tend to "tap" with the foot pedal when working carefully, so I can see how a control for that would be helpful.

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OK. So I made a basic video of the press cycling operation and how to set the depth, etc. This was a lot more complicated than I thought it would be. I actually had to create a YouTube channel for our business (Dos Gatos Designs LLC) and the video is uploading as I type. It has about 53 minutes remaining in the upload process (who would think it would take so long?) I may have to go to bed before it completes uploading. I may have a few more buttons to click on the YouTube site before it publishes, who knows what this all entails........I will keep you posted.

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OK, so it looks like the knuckle-dragger has actually managed to do this. I will try and get another video made with some hot steel soon.

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Too cool! Thanks indeed. One of these days if I ever get a press I want that kind of control. This is speaking from experience after having bitten off the end of a sword blade on a friend's press a few years ago... :rolleyes:

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Too cool! Thanks indeed. One of these days if I ever get a press I want that kind of control. This is speaking from experience after having bitten off the end of a sword blade on a friend's press a few years ago... :rolleyes:

 

 

I'm also a big fan of putting measured spacers in the dies for that reason... :)

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OK, so it looks like the knuckle-dragger has actually managed to do this. I will try and get another video made with some hot steel soon.

 

 

Very cool setup. I'm interested to see the video of the setup in action. If you don't mind my asking, what did the control setup set you back?

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I bought everything as a unit (press and controls) for $4K from the guy who designed the controls. He was upgrading his press.

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Here is the press in action drawing out a block and resizing it from 1-1/2" x 1-7/8" x 5" to 3/4" x 2"x 9-1/2"

 

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that is a really great system, I like it a lot.

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That is pretty kick ass. If I ever outgrow my Uncle Al's press (which i doubt, since this is just a hobby for me, and i get WAY too little shop time as it is) I'll build somethign along that line as well, because thats too cool =)

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Thanks for posting it Joshua

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You know, if I had the time I'd like to do things, I'd build something similar based on a little microcontroller so that I could log all of the up/down action with timings to graph and see where I could be more efficient in my forging...Sometimes it really sucks having the skills to do things without the time or money... :)

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That is so nifty I'm pinning this thread! Thanks for showing us.

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I'm honored Alan. Maybe I can get Jeremy to provide some contact information and pricing for anyone who is interested in getting this setup on their machine.

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I guess I have the responsibility of making more videos of the press doing other stuff and adding them to this.........

Any Ideas on something you guys would like to see, let me know and I'll try to figure it out.

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Please pardon my first post here for going all technical and high-brow. I do heavy industrial fluid power in high tonnage apps. Google youtube hot strip mill or hot forging press for ref. Haven't seen your video, so questions are blind and are more for design safety suggestions.

 

What pump style? Oil type? Have an accumulator? Newer hoses? Proper rated tubing? Secondary pressure line relief? What kinda tonnage you after?

 

My immediate thoughts while reading was massive pressure spikes and 'water hammer' during cycling, if using fixed displacement pumps and 'bang-bang' solenoid valves, leading to blown seals, sheared couplings, and general premature grenade-ing of the thing. Variable vane or piston pumps tandem with an accumulator would safely reduce system pressure shocks and energy costs.. Once I thought about a micro servo valve with an external LVDT, the easy and precise way to do hydraulic position cycling, I thought to post my questions, since simple and cheap is best and more broadly doable. Plus. there's so many ways to do what your doing. Once I get to a proper workstation, I'll look at the ladder diagram and videos for the clearest view and to offer constructive suggestions.

 

Cheers,

AL

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