Press idea floating around in my head, may just have to let it out.

[j.w.s.]

So I've had this idea in my head for a while now and sort of took a step towards building it a few weeks ago when I put my hydraulic press up on Craig's list where it promptly sold. I dont have a huge shop so floor space has always been an issue. Anyway, my idea came about when I built a rolling mill based on MacDonalds plans. My desire is to use the stuff I already have like a 4 inch 1200psi hydraulic cylinder and the air over cylinders that run it etc. Now this cylinder will comfortably push 8k to 14k lbs which is nice but nowhere near what I need a press to do. Its 8" of stroke. This is where the mill got me thinking. The rolling mill uses a lever to take my 180lbs and multiplies it to a few thousand. So what if I cut some heavy duty levers out on my cnc table and transformed that 8" stroke into 55 tons? An 8.75" lever with a fulcrum inset .75" from the work would deliver over 110k lbs at just over 10k lbs of push from the cylinder and give me almost .75 inch of compression which is more than. Enough for setting welds in billets and even drawing out. The overall height between dies could be set with lead screws. I'm thinking a c-frame design and I'm not afraid of over engineering to get safe results. So anyone care to throw some input at me? Has anyone ever done this before?

J

[Stash]

I don't really do this kind of stuff, but my first thought had to do with the size and alloy/ shear strength of the pivot pin. Over-engineered as you say, though, it should be a fun exercise. In progress pix are great.

 

Steve

[j.w.s.]

I don't really do this kind of stuff, but my first thought had to do with the size and alloy/ shear strength of the pivot pin. Over-engineered as you say, though, it should be a fun exercise. In progress pix are great.

 

Steve

 

Weird, that was odd. Yes, my main concern is that I could be building a giant shear for round stock. lol I've got some ideas and loads more thinking to do until I start the actual build, but when I do I promise pictures. :)

[Frosty]

J: What you're thinking about is the same mechanism used to put the STOP in air brakes. The lever converts the lineal motion of the brake can into rotational force that turns the cams that open the brake pads.

 

Fingers crossed, Tinyurl used to be a lot easier to use. <sigh>

 

#7 on this page. http://tinyurl.com/klxpgox

 

You can also make a compound lever that will develop scary huge psi.

 

Frosty The Lucky.

[BryanWillman]

This is kind of 1/2 of a toggle press.   In addition to needing the pivot to be very strong so you don't just shear it off, the lever (toggle arm/arms) needs to be able to resist the bending/buckling forces.

[Alan Evans]

Snip... give me almost .75 inch of compression which is more than. Enough for setting welds in billets and even drawing out. The overall height between dies could be set with lead screws. I'm thinking a c-frame design and I'm not afraid of over engineering to get safe results. So anyone care to throw some input at me? Has anyone ever done this before?

J

 

Hmmm. Sounds like taking the one of the advantage of a hydraulic cylinder over a power hammer which is that it has the same power anywhere on its stroke and throwing that away for what? If you can see that a 55tonne .75" stroke can be useful for your forging then great. I am always looking for extra capacity from the point of view of stroke length and clearance between dies from all me presses and hammers. Changing the stock size parameters with lead screws mid-heat sounds a bit of a non-starter, what about tapers or is everything you forge parallel?

 

Alan

[arftist]

My only comment concerns your desire to build a C-frame press. 

While I understand the theoretical increase in versatility the stresses increase in manifold manner.

 

In fact, given that the larger the throat, the greater the the stress, it is likely that you could have a greater opening in an h-frame press for 1/4 the material cost and weight. 

 

Otherwise your idea has good merit with the possible exception that whatever you gain in force you will proportionally lose in speed. 

As you are likely well aware, speed is similarly important to force in hot forging press work, as the dies start to rob heat at the instant of contact. 

 

Alan; he is talking more of an almost closed die setup than freeform adjust in mid heat forging. 

[Alan Evans]

Snip...

 

Alan; he is talking more of an almost closed die setup than freeform adjust in mid heat forging. 

 

Ah right, thank you.

 

 I was puzzled by the limited function of the proposal. And I could not square the limited floor space with the lack of versatility.

 

I also am tight for space so the more versatile the machine the better. My little 30 tonne press is only a couple of feet wide and four or five deep and that will do tasks requiring either a 0.75" or a 0.75' stroke with equal aplomb. 

 

Having reread the OP though...0.75" from the fulcrum what happens? how do you connect to the top die? Is it a cam acting on a top plate?

Just curious.

 

Alan

[arftist]

It is a lever and pivot affair. Google up metal muncher ironworker. The coper on the opposite end from the punch is what this fellow wants to emulate. 

[Alan Evans]

I had a look at the metal muncher and I think that is the sort of thing I was envisaging. All the early ironworkers over here were mechanical, derived from the constantly cycling shears and punches in the water mills.  I have to admit it was the punch end of the metal muncher I thought he was going to use.

 

Even so it is the 0.75" from the fulcrum that I am having difficulty with, how is that transferred to the tooling…what diameter can the pivot pin be if the operating length is only 0.75"?

 

Or is it an actual fulcrum; a 0.75" difference cam lobe operating between the frame and pushing on the top tool?

 

Maybe I am just being dense again. Sketches would help.

 

Alan

[arftist]

I had a look at the metal muncher and I think that is the sort of thing I was envisaging. All the early ironworkers over here were mechanical, derived from the constantly cycling shears and punches in the water mills.  I have to admit it was the punch end of the metal muncher I thought he was going to use.

 

Even so it is the 0.75" from the fulcrum that I am having difficulty with, how is that transferred to the tooling…what diameter can the pivot pin be if the operating length is only 0.75"?

 

Or is it an actual fulcrum; a 0.75" difference cam lobe operating between the frame and pushing on the top tool?

 

Maybe I am just being dense again. Sketches would help.

 

Alan

 

The pin could be 75mm as long as the center of the pin is .75" from the end. 

 

He has chosen to work in tiny increments for whatever reason. What matters is the ratio of the lever from the work end to the fulcrum vs the overall length or in his calculations. aprox. 11 2/3 to 1. So, perhaps it is easier for you to visualize if we treble the size maintaining the same ration; lever length becomes 26.25" and fulcrum center is 2.25" from work end.

 

As for the metal muncher, perhaps you are correct, it has been years since I have seen one; I assumed the cope would require more force than the punch. Either way, the theory is represented. 

[j.w.s.]

I'm choosing to work in tiny implements for the simple reason that I make knives and swords for a living. Its what I've been doing for decades and have no intention of tapering etc with it. :) I need the press for the simple actions of setting welds in billets and drawing them out prior to doing the rest of the drawing in my rolling mill, air hammer or by hand. Lead screws arent playing out well in my mind, and I'm leaning towards plates of various thickness to raise the lower die closer to the top one, its clumsier but I dont need instant adjustments for my purpose. Less chance of mechanical failure. For moving the top die down a simple cam will do the job quite well. Someone mentioned shearing of the pin, quite frankly I dont mind making 2.5" or larger pins to stand up against the forces. I have a plasma cnc table on which I could cut the actual levers out of 1.5" plate if necessary. Like I said, im not afraid to over engineer. I understand the limitations of a c-frame verses h and the more I think about it, my design is coming together as a hybrid of the two.. sorry, in the middle of doing demonstrations all day so I'm just browsing through this quickly on my phone and addressing the points that stand out in my mind, I'll make a point to re-read once I get back to the office. :)

-J

[clang]

I'd respectfully suggest that, since you have a severe floor space limitation...

You just go out and get a big fat hydraulic cylinder and be done with it.

Safer, faster quicker and easier to get it working.

[j.w.s.]

Started. Not as big as it could be but not a slouch either. :)

J

[j.w.s.]

I decided to opt for all cylinder operation.

J