Hydraulic power press design

I'm investigating building a powered hydraulic press for draw die
work. The press would be used for tryout only, meaning no production.
I could easily imagine the press being hit less than a thousand times
over its entire life.
Capacity would be 50-100 ton
Front-to-back working would be about 12"
Left-to-right working would be 18"
Stroke would be 10"
Closed daylight would be about 10-15"
I was considering just using three major plates: the bolster, the ram,
and the crown (on which the cylinder is mounted), and using four tie-
rods to keep everything together.
My questions refer to the size of plates, and the size of tie-rods/
guide-rods.
As I understand, hydraulic presses aren't really capable of creating
severe overload conditions (in contrast to mechanical presses). So,
what would be an appropriate safety factor for the tie-rods? 2:1? 4:1?
If the tie-rods were 4140, a single 1-1/2" rod should be able to
withstand the press's entire capacity.
I have no idea how to calculate the required thickness of the three
plates, to withstand the load without severely deforming. The die
shoes used would always pretty much consume the entire working area of
the press. While the loading wouldn't necessarily be balanced (due to
the type of die work), there won't be any pin-point loading on the
bolster or ram. Bolster to ram parallelism is actually quite important
in this application, although the die shoes will assist in resisting
deformation, in addition to the bolster.
While the die shoes will have their own guidance (pins and bushings),
the ram should be guided as well to assist in preventing severely
unbalanced dies from deforming under maximum loads (remember - this is
tryout... Things happen). I'm not sure if it would be a good idea to
have the tie-rods act also as guide-rods, or if they should be
independent. They seem to be the same thing on commercial presses...
Any thoughts are welcome. I want to build instead of buy because gap-
frame and 4-post presses of this capacity seem to be much larger (FB/
LR) than I need, and I don't want to have to deal with a 7500lb
monster if it's not required.
Regards,
Robin
Reply to
Robin S.
Loading thread data ...
Yer off into whacko-lands, kiddo...
Basic hyd.
PSI
HTH...
Reply to
Jeffrey Lebowski
Press loading in the vertical diection is not a big deal. You will have a huge issue keeping the die set plates both parallel and aligned without resorting to the massive frame of a standard press frame. Off center loading of any progressive die will overwhelm the ability of the die pins to keep it square.
Rob> I'm investigating building a powered hydraulic press for draw die
Reply to
RoyJ
He wasnt even asking about progressive dies.
Reply to
Jeffrey Lebowski
Find somebody in your area with a press and borrow it a thousand times. Or, buy a used one. Your project is like building a cruse ship for one trip. Sorry...
Reply to
Tom Gardner
I can get you a 150 tonner for very very little money here in So. Cal.
Gunner
The aim of untold millions is to be free to do exactly as they choose and for someone else to pay when things go wrong.
In the past few decades, a peculiar and distinctive psychology has emerged in England. Gone are the civility, sturdy independence, and admirable stoicism that carried the English through the war years . It has been replaced by a constant whine of excuses, complaints, and special pleading. The collapse of the British character has been as swift and complete as the collapse of British power.
Theodore Dalrymple,
Reply to
Gunner
As a panel die maker, I'm aware of the dynamics of press work. I'm looking specifically for some guide to help me decide on the size of the press bolster. Certain types of die-making do not allow for balanced loading. I'm not doing progressive die work anyway.
It sounds like looking at examples of presses on the internet is likely the best method for deciding on a bolster thickness. I'm assuming I won't know exactly what the bolster is doing until I assemble the thing and go after it with a dial indicator.
Regards,
Robin
Reply to
Robin S.
Tom,
I'm not sure how familiar you are with die tryout. Production presses probably make more strokes in a week than most tryout presses make over their entire lifetimes. The tandem presslines at my previous employer's customer's shops would make thousands of panels per week. Our tryout presses would make perhaps a couple dozen hits per day, at best.
I was thinking I could make one cheaper than I could buy it. Again, it's hard to find a press with the specs I'm looking for. My specified working area is fairly small for its tonnage capacity.
Regards,
Robin
Reply to
Robin S.
I have a feeling it would be way bigger than I need (or can reasonably accommodate) and I don't even want to think about shipping. What's the FB/LR specs, roughly?
Regards,
Robin
Reply to
Robin S.
No
Reply to
J. Carroll
Hydraulic presses are frequently custom built for specific applications. The hydraulics involved (brand new) would be about $2k, including valves, cylinder and power pack. Another $3-500 for automation, and then the steel and bronze. New press (used presses can be in *really* bad shape, while still going up and down on the factory floor), correctly sized, exactly what I want...
I'm not worried about creating the force, I'm worried about dealing with the force. I'm really just looking for safety factor info (tie- rods) and deflection (bolster).
Anyone?
Regards,
Robin
Reply to
Robin S.
Don't piece this out Robin. What are you trying to do? Here, let me help you out. "I am in the process of building a company to do________" I still think my advice earlier was spot on.
Reply to
J. Carroll
Die building. Build only, not production. I need this press for tryout work. Perhaps I should start phoning used machinery dealers. I just assumed used presses would be fairly expensive. Perhaps I should actually check that before getting into something that's more work than it's worth (duh).
Well, I certainly see where you're coming from. However, that's not what I'm worried about at this stage of my life. Right now I'm interested in a press and a CNC machine.
Regards,
Robin
Reply to
Robin S.
Ned,
This is *exactly* what I had in mind. Looks like 3" plate is a good plan. Thanks a ton for the link. Perfect - really.
Do you mind if I ask you what they're worth? My e-mail works, if you'd prefer...
Excellent.
Regards,
Robin
Reply to
Robin S.
Call Brett Blanchard at Artisan. They are in Livonia, Michigan.
It was a personal comment based on experience and I would not have offered it had I not given a shit. One dumb fuck to another if you know what I mean.
Robin, You won't be and wouldn't want to be the next Magna. Take my word for it. Been there, done that. Ever heard of Starboard Industries or Chivas Products?
I'd trade that history for a family.
Reply to
J. Carroll
I see your point and understand. You might be right building it if you can't find what you want readily. I'm blessed with a plethora of used equipment in a 20 mile radius with probably 30 hyd. presses at any one time. Sorry if I sounded flip, my mindset takes over now and then...but I did like the idea of borrowing it a thousand times!
Reply to
Tom Gardner
You'd have to tell me why first. No web address as far as I can tell...
Fair enough. I don't have a family right now, not even one on the horizon. When I'm young, right?
I'm not saying you're wrong. But I think this is right at this point in my life.
I looked them up briefly (tonight's busy). I'm not apart of Magna any more. Not really trying to be the next one. This is just something I've been wanting to do for several years now. Because of timing, I finally have the option of doing it...
Certainly a lesson I'll need to learn myself. But I'll keep your advice in mind. I didn't wake up last week suddenly wanting a machine shop. Again, years of thought. Perhaps not enough thought about the nitty-gritty details, but I think the dream has to come first. Things like money are incidental ;-)
Regards,
Robin
Reply to
Robin S.
Right now I'm definitely trying to feel out which direction I should go. I will be calling around for presses. Perhaps tomorrow or the next day. I really have no idea what to expect... Building is an option though.
Regards,
Robin
Reply to
Robin S.
There are some examples here that may be helpful. I just priced a couple 30T presses from Tox with a work envelope similar to what you're talking about. It looks like you need to download the .pdf catalog to see the larger presses.
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Ned Simmons
Reply to
Ned Simmons
I'm not very interested in how thick to make the bolster or how big to make the the guide pins/press posts. I want to see how you plan to take the torque loads. Visualize a 100 ton ram coming down on a load 12" off set from the center of the ram. That 200,000 pound-foot load has to be absorded by the pins/posts without bending or siezing.
The problem with home brew presses is that they do not usually have the necessary rigidity to take the to torque loads generated with off center loading. That torque will apply a bending load to the die set pins and/or press frame, tends to jam things up. I've had to deal with the screaming when an operator raised the ram in a 150 ton hydraulic press, one pin seized, next cyle brought the top half of the die down at about 10 degrees off of flat. VERY NASTY results.
I've also had to live through the company founder wanting to build a 100 ton horizontal press using multiple rams. Spent a bundle of time and money, never did get it to maintain parallel ram/bolster orienation.
Rob>
Reply to
RoyJ

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