In over my head on a press die

[rottenleonard]

Great site here!!
I'm hoping to borrow some of the knowledge from the board here,
I have been building these seats for a while using a bead roller to do the design work. I wanted to start stamping them to produce them faster and more accurately.
http://www.meachamrifles.com/images/Hot%20Rod/Bomber%20Seats.jpg


I built a shop press and I'm using a air over hydraulic setup with three 10 ton rams, I am not getting anywhere near an acceptable product and need help deciding if I need to change directions completely or just beef up the press and add more power.

Here is what I have built (no laughing)

http://i559.photobucket.com/albums/ss34/rottenleonard/press%20die/HPIM4001.jpg
http://i559.photobucket.com/albums/ss34/rottenleonard/press%20die/HPIM4002.jpg
http://i559.photobucket.com/albums/ss34/rottenleonard/press%20die/HPIM4003.jpg
http://i559.photobucket.com/albums/ss34/rottenleonard/press%20die/HPIM4005.jpg
http://i559.photobucket.com/albums/ss34/rottenleonard/press%20die/HPIM4006.jpg
http://i559.photobucket.com/albums/ss34/rottenleonard/press%20die/HPIM4007.jpg


Sorry for the poor quality pictures


And this is what it produced, really didn't work at all :???:

http://i559.photobucket.com/albums/ss34/rottenleonard/press%20die/HPIM4004.jpg

[Joe Andrews]

Couple of questions...
Are you using some sort of rubber under your sheet metal?
A rubber pad will add greatly increase the detail being transferred.

Do you think your getting enough Pressure?
Even though you have 3 10 ton jacks your only going to get 10 tons of force.

If your using a Rubber Pad and only getting that much detail then I would guess that more tonnage is needed.

Your last picture shows a lot of what's going on. There is a lot more detail being transferred on the top edge of the Panel. The beads disappear as you the panel comes toward you. That's an Alignment Issue, you need to have even contact to get what your looking for.

Keep at it, and the Seats look Very Nice .

[rottenleonard]

I am not using any sort of rubber mat, is this something that I would use instead of the lower die?

As I understand it I have three rams that are rated at 10 tons @ 10,000 psi each so wouldn't I have 30 tons with each ram getting 10,000 psi?

[TheRodDoc]

Think you will need way bigger press. As far as I know, three 10 ton cylinders still only apply 10 ton. Probably less if they arn't putting out that full capasity.

[oldgoaly]

I notice the ends of the side are extending past you upper ram. some how you need a wider than the part "platen" otherwise no pressure is being applied to those areas

[rustydog]

take a look at this thread

http://********shaping.com/showthread.php?t=2171

you can buy these cheap, there was one on Ebay last week for $800

Rusty

[dmc1]

If those three jacks were stacked up end to end, they'd produce 10 tons force. With them working in parallel as shown, the total force is 30 tons ( assuming they're rated correctly).

I can't understand why anybody would say differently.

Dave Cameron

[NewOCork]

Put a pressure gauge on the hydraulic line, the pressure will be psi x total area of cylinders. That will give you an idea where you are at.

Corky

[NewOCork]

A couple of more thoughts

Do you have enough fluid in the system for full extension of the rams? The reservoir looks small.

The bottom plate looks rather light and your sample looks like something flexed, type say 1" plate.

Try making samples with just a small piece of scrap say 6" wide in different parts of the die, that may tell you a lot.

Corky

[Joe Andrews]

I agree that you have some twisting going on. That has to be corrected. Using Rubber lets you make a Single Die that can be pressed into a Cavity that roughly matches your die. The Cavity does not have to be perfect, if you notice your not getting detail in an area on your panel its because the rubber is not filling the voids. The voids can be built up with a number of different materials. Using thick Rubber the press squeeze the rubber into every bit of detail your die has.

this video shows the process making half of a cycle frame. The Guy calls it Hydroforming but this is not hydroforming. This is Simply Press forming.

http://www.youtube.com/watch?v=YQm9g6g1kIw&feature=fvsr

[Doug98105]

Check the tonnage, are you getting 10,000psi out of the pump? Iinvest in a gage, it's handy to know what kind of forces you're working with when pressing.

Assuming you do have 10K psi, 30 tons must not be enough.

Here's a simple way to verify your press tonnage. If it'll bend a 1" x 3" mild steel bar spanning over a 6" gap then you're getting very close to 30 tons out of it.

You can reduce the needed tonnage on your parts by reducing the die clearance. Clearance would be the space between the upper die and the lower die. How much clearance do you have and what's the material type and thickness?

You could use soft or half hard material, that'd help.

You could also make another die set to do the pressing as a two step process, beads in one pressing, then the offset around the edges in another pressing.


Doug

[Doug98105]

I agree that you have some twisting going on. That has to be corrected. Using Rubber lets you make a Single Die that can be pressed into a Cavity that roughly matches your die. The Cavity does not have to be perfect, if you notice your not getting detail in an area on your panel its because the rubber is not filling the voids. The voids can be built up with a number of different materials. Using thick Rubber the press squeeze the rubber into every bit of detail your die has.

this video shows the process making half of a cycle frame. The Guy calls it Hydroforming but this is not hydroforming. This is Simply Press forming.

http://www.youtube.com/watch?v=YQm9g6g1kIw&feature=fvsr


Joe,

Rubber won't work in this case.

The problem is apparently he has too little tonnage in his press. Rubber or urethane takes more tonnage than a set of hard dies like he's made. With rubber a good deal of the press tonnage is "wasted" deforming the rubber.

In the video they had to use a fairly hard grade of rubber because it isn't contained. A softer rubber would work just as well with less tonnage except it'd "squirt" out the sides if it wasn't contained.

Doug

[RedBeard66]

Looks to me like you have enough pressing force. it's only aluminum after all. your problem is your tooling is WAY too complicated! your part is very simple. your bottom die is good but your top die is where you've gone wrong. just make your top die exactly the way you made the bottom only opposite. if you want your draw depth to be 1/8th inch use 8th inch plate welded to a piece of heavier metal and then reverse it for the top. you can even press multiple times in different spots if your part is large. also alignment pins through the tool and the blank are a MUST for proper alignment. remember when making your top die to account for metal thicknesses or it will sheer. I've done many pressing operations this way and some more complicated then what your trying and i've always had good luck with it. hope this helps

[NewOCork]

I don't know the diameter of your rams, but assume 1" and operating pressure of 2500 psi. The area of each would be pi*r*r or about .75 sq inch or ~2.4 sq in for all three. At 2500 psi the pressure of all three would be 5890 lbs or about 3 tons. The rams maybe rated at 10 ton, but you may not be getting to that pressure. At 30 tons and 2500 psi, you would need about 8 sq in per ram, or for three cylinders of ~ 3.5 inches assuming I did the calcs correctly! Next I would assume you need perhaps a gallon oil tank to drive those cylinders.

A cheap solution maybe be a Harbor Freight 20 ton air assisted jack like item #97453.

Second I would wonder about the strength of the frame. When things break under high pressures a 1/2 bolt acts like a bullet!

Be safe!

Corky

[tusk]

Well Rotten or what ever your name is, I'm totally going with Richard on this one.
I beleive ya still have 10ton.
You can put 20 of those cylinders on the press and ya still have 10ton.
I'm not an engineer or a pressing manaic, but I have learned a few things on this.
Two yrs ago at Randy's I decided I was going to make the lower panel on the inside of a whatelse? Willys door. The panel has 5 or 6 beads in it and randy has a die and I'm gonna press somthing. His orginal press looks like yours after he pressed one some time back. Looks like ya already bent the snot outa the top beam.
Randy has a trim press that wasn't running but with 11,000 lb. of iron sittin there I'm not going to bend the press.
I used a 20ton bottle jack and a 12ton. It surly did not equait to 32tons at all. The 12ton was pretty much along for the ride.
I messed around for about 5hrs befor I finally got a nice peice. Once I figured it out the next took 45min. to do.

Now I dought very much that those cylinders will take 10,000 psi unless the cyl. walls are 1" thick.
If you take a 6" dia cyl. at a typical 2000 psi it does about 30tons. But thats 30ton over a 6" circle, make that circle any shape ya want it has 30tons of force there. You go to a bigger area your tonage just went down.
Would 30ton do it? I myself don't think so with the die ya have, but could done differently.

Many can agree & many can disagree, I know what I know.
I had the finished peices at MM and they do look nice.
My two fingers are tired from typing.
Doug

[Doug98105]

Well Rotten or what ever your name is, I'm totally going with Richard on this one.
I beleive ya still have 10ton.
You can put 20 of those cylinders on the press and ya still have 10ton.

.................................................. .................................................. ....




Look at it this way, pretend each of those cylinders is a man pushing a car. One man pushing can't do it. Two men are having a hard time. A third man comes along and they can push the car. Total force is the sum of all three men's pushing forces.

The way he has the cylinders setup, the total force is the sum of the force of all the individual cylinders. 10 ton + 10 ton + 10 ton equals 30 tons. Whether his pump is actually putting out the pressure necessary to develop 10 tons per cylinder is another question.

Here's his pump, rated at 700 bar, 10,000psi:
http://www.directindustry.com/prod/enerpac/air-operated-hydraulic-pumps-14336-367503.html

You can see the pump in his 6th picture off to the left on the floor, an Enerpac air driven pump. I have the same one. They max out at 10,000 psi. That's the amount of pressure those type cylinders need to give maximum force.

His press doesn't have a pressure gage so we don't know how much pressure he's actually developing. He can verify his press tonnage simply by trying to bend a steel bar as I said in post #11 of this thread. The bending I described takes almost exactly 30 tons.

He either needs to change his dies, or increase the press tonnage. High pressure cylinders like these are expensive. Rather than invest more money in larger cylinders he can modify his dies to do the job.

There's nothing wrong with his basic die design, the press at 30 tons just doesn't have the enough force.

Doug

[captainkirk]

Interesting subject, it seems from a bit of reading that the forces applied are not that simple to calculate when ganging cylinders in a pressing operation.

If the math is done properly then there is an area of differing forces that gets applied to the object under the multiple cylinders.

Here is a PDf on the subject that explains the situation. (or seems to to me)

http://www.lemacher-hydraulik.de/pdf/en/Gleichlaufgesamtprospekt-en.pdf

[bobadame]

I see a couple of things. Your punch looks plenty stiff enough to do the job but the die and the 2 channels supporting it might be flexing away from the punch. Try putting a straight edge under the channels when the process is at maximum tonnage to see how much it flexes. Check your alignment with something softer like annealed 24 gage aluminum. This will also show you if you have enough vertical travel in the system.
Adding cylinders will add force to the process. Force is simply pressure times area. After you stiffen up the bottom this will help since some of the work that your pump is doing is to flex the press. This is assuming that the pump has enough travel to supply enough oil to fill the additional cylinders and move them far enough to bottom out the process. Also if you grease the sliding surfaces of the punch and die it will move the metal easier.

[rottenleonard]

Wow great responces, This is help I really appreciate!

I scanned CaptainKirk's pdf file, there is a lot of info to absorb and I'd like to read it a few times to retain the info for sure, As for the 10-ton to 30-ton issue I feel pretty confident in my theory there, however I do agree that I need a gauge to see if my pump is producing correctly, as for resivore size I have blead out the system at the position the rams are now in and only need the system to move about a 1/2 inch granted if i collaped all three cylinders i will have a major overflow but at this point I am just triing to do the minimum to see if I can really make this happen before going back threw and refining the project.

As a few of you mentioned flex is a major issue and so I pressurized everything again and I am getting almost a 1/2" of deflection in the lower rails of the press, and the channel that ties the three rams together has large dents under each ram, I think I am going to try to build a truss for the lower rails that attaches to the ends of the rails and forms a triangle below the center of the rails with a jack screw to preload the rails in the opposite direction. I'll try to make a drawing of what i'm poorly describing shortly. as for the channel that ties the rams together I think I'll just get some 1/2" x 4" plate to sandwich to it to beaf it up.

If I can eliminate the flex, and still do not have the needed results I guess I could start adding more rams? But I will need some help determining the failure point of the components in the press.

[whateg01]

I agree with Doug that the force being applied is the sum of all three cylinders. The pressure does not change; maybe that is the source of confusion. Whether 30T is actually being generated or not is impossible to tell without a gauge.

I don't think that the rubber is necessary here. But there are a couple of areas where I see room for improvement.

First, as mentioned before, the bottom female die needs to be beefier. Just like the upper die is effectively 6-ish inches thick, so too should the bottom die, or at least tall enough to not deflect.

Second, stamping this in sections will require less force and the force can be more concentrated. With the right reference marks, repeatability should not be an issue.

Also, I don't know if you are using any, but some sort of lubrication on the workpiece should allow it to draw in material from near the shapes to reduce the chance of tearing and to lower the force required.

Dave

[rottenleonard]

I agree with Doug that the force being applied is the sum of all three cylinders. The pressure does not change; maybe that is the source of confusion. Whether 30T is actually being generated or not is impossible to tell without a gauge.

I don't think that the rubber is necessary here. But there are a couple of areas where I see room for improvement.

First, as mentioned before, the bottom female die needs to be beefier. Just like the upper die is effectively 6-ish inches thick, so too should the bottom die, or at least tall enough to not deflect.

Second, stamping this in sections will require less force and the force can be more concentrated. With the right reference marks, repeatability should not be an issue.

Also, I don't know if you are using any, but some sort of lubrication on the workpiece should allow it to draw in material from near the shapes to reduce the chance of tearing and to lower the force required.

Dave

I havent thought about lubing the dies, what is a good lube that cleans up easly? I could see how that would make a large difference!

[whateg01]

...
As a few of you mentioned flex is a major issue...

Tall vertical sections are your friend. Trusses could be used, but they will still rely on having verticals in the right places. A tall section of even "thinnish" plate will do better than a truss. In a truss, all of the areas between verticals need to be rigid enough to resist deflection between said verticals. A gusseted section of I-beam would serve you better, I think.

Here again, breaking this up a little reduces the force as well as concentrates the area over which force is required. Maybe do the lines in the seat back, then the lines in the lower area, then the perimeter (if applicable)?

Dave

[whateg01]

One other note on hydraulics...

This applies to all fluid flow, not just liquid, so this can be applied to air systems, too. The fluid is going to go the area with the least resistance first. So, if one of the cylinders encounters less resistive force (the web of the channel deflects more easily) that is where the hyd. fluid will flow. When the resistance encountered equals that that the other two cylinders are seeing (or the next least resistive movement), then it will be split between those. This repeats until all of the cylinders are encountering the same resistance, whether you have 2 or 200 cylinders. (This all assuming a common supply.)

Imagine, if you will, a couple of balloons on a manifold. You pump air in and one of the balloons airs up first. If you squeeze that balloon, the air goes to another. If you squeeze both at the same time, you can make them the same size by modulating the squeezing. This is the same thing that happens with the cylinders.

Dave

[Terry Stolarski]

Looking at the picture it is hard to tell, but it looks to me like the slots in the bottom die are not big enough for the metal to go into, not enough clearance. What do you guys think? or maybe it's the picture.

[whateg01]

It'll go... with a big enough hammer! :D

You did make me go back and look again, though. BTW, when you are forcing metal to stretch around shapes, like you are here, every imperfection will show up. Maybe it is the pic quality, but it looks like some of your edges are not straight. Since the goal is to make more consistent, repeatable shapes, I think I would check that. If you have a milling machine, they could be cleaned up mighty nice. ;)

Dave

[DYCE]

Looking at the picture it is hard to tell, but it looks to me like the slots in the bottom die are not big enough for the metal to go into, not enough clearance. What do you guys think? or maybe it's the picture.

Terry I was thinking the same thing.

[rottenleonard]

Terry I was thinking the same thing.

I do have twice the thickness of the metal's clearance in the slots, the punch portion of the slots does need to be polished substatially, and will happen in due time.
I have a 10k psi gauge on order, and Im building a "box" for the lower die to match that of the upper, also going to try the truss idea on the lower rails of the press to eliminate flex there.
I'll post pictures when i get it done hopefully this weekend and I'll try punching another piece and post pictures of the results.

I havent done any web searching yet but what is typically used for lube on something like this?

[DYCE]

http://i559.photobucket.com/albums/ss34/rottenleonard/press%20die/HPIM4005.jpg

When you get your gauge set up and get some pressure on it check your press frame for flex. I swear that top beam has a bow in it. Get a measurment with a tape, with the frame at rest, and as you put pressure on it take a tape measure and measure the gap between the upper and lower beam at different pressures.

[bobadame]

It would be interesting to do a single bead of maybe 6" length. Use one cylinder. Do the bead at right angles to your current setup so that frame flex isn't an issue. Read the pressure gauge and see how much pressure it takes per inch of length. Then you can figure out how many square inches of cylinder area at that pressure it would take to do the entire piece. Once you know that, then you beef up the press with maybe some big tie rods across the center of the span and give it another go.

[Doug98105]

.................................................. ..............................................

I havent done any web searching yet but what is typically used for lube on something like this?

Some of the factors in lube for high production are how easy it is to remove and cost.

For your limited part runs about anything will work. I use a light weight tapping fluid (about like a 40 weight oil) or water soluble cutting fluid undiluted. Both rinse off with water and leave a rust prevention coating. Those choices are mainly because I have them.

Doug

[rottenleonard]

http://i559.photobucket.com/albums/ss34/rottenleonard/press%20die/HPIM4005.jpg

When you get your gauge set up and get some pressure on it check your press frame for flex. I swear that top beam has a bow in it. Get a measurment with a tape, with the frame at rest, and as you put pressure on it take a tape measure and measure the gap between the upper and lower beam at different pressures.

I really hadn't looked closely at that picture, the picture must have been skewed when it resized or uploaded, in that picture there is no pressure on anything and both the upper frame and the lower rails are still straight.
When loaded the upper frame stays very straight as it has quite a lot more metal built into it, while the lower rails do deflect.

[Richard K]

I asked a friend of mine about this type of work. He is over 70 and has been a die maker for this sort of stuff all his life.

He says:

1. Everything involved needs to be extremely rigid.

2. A platen press would be good as it spreads the pressure evenly over the work. In not a platen press then the dies need to be massive to push evenly.

The last die I saw him complete last year was for a truck muffler end about the size of a turkey platter. Maybe 14 gauge steel part with not too much shape. The die set cut the blank and formed it. The dies looked to weigh maybe 400 pounds and it ran in a huge punch press. Last week he was troubleshooting a die for someone. The die formed a part like a motor mount bracket made of 1/8'' steel sheet. the blank was maybe 8x8 inches. It was a multi step die in a 750 ton punch press.

The forces need for this press work are tremendous.

Use caution when attempting such work. If anything fails; the results could be very serious.

[rottenleonard]

Well here is a progress report, I built a die support for the lower die, and built the truss for the lower rails, the truss works great there was virtually no deflection when pressurized. There is about a 1/4 inch of deflection in the upper portion of the press, which shouldn't effect anything but I think I will add a truss there just because it's cheap and easy.

http://i559.photobucket.com/albums/ss34/rottenleonard/press%20die/HPIM4020-1.jpg
http://i559.photobucket.com/albums/ss34/rottenleonard/press%20die/HPIM4011.jpg

http://i559.photobucket.com/albums/ss34/rottenleonard/press%20die/HPIM4012.jpg





I decided to take many of yours advise and split the process into steps, so I milled out the slot punches from the punch die.
http://i559.photobucket.com/albums/ss34/rottenleonard/press%20die/HPIM4013-1.jpg

I tried it again and seemed to get better results but could tell it wasn't quite there, so instead of backing it off to read the part I simply mashed the go pedal, suddenly the press made a funny shift motion, and I noticed the uprights had stretched. I had felt they were suspect, but used them anyways because they were free from the scrap pile, and like most free things do they create more work!

http://i559.photobucket.com/albums/ss34/rottenleonard/press%20die/HPIM4018-1.jpg

http://i559.photobucket.com/albums/ss34/rottenleonard/press%20die/HPIM4017.jpg


So the plan now(unless anyone smarter than me objects) I will replace the side rails with 2"x4" 1/4" wall square tubing which will also allow me to step up the size of the pins from 7/8" to 1".





Someone had mentioned that the bolts holding my upper rails could turn into bullets if they fail (I hate getting shot) I was thinking of replacing the 20 grade 5, 1/2" bolts with 10 grade 8 bolts that sandwich the new uprights and upper rails, Does anyone have a way of projecting the strength of these joints?


http://i559.photobucket.com/albums/ss34/rottenleonard/press%20die/HPIM4019-1.jpg



As for the results, one side looks acceptable, the other shows signs that that the die is just too tight, once clearanced I think it will work fine. I had clearanced it so it was hard to slide the material in arould the die but I think it needs to be a little looser.

http://i559.photobucket.com/albums/ss34/rottenleonard/press%20die/HPIM4014-1.jpg

http://i559.photobucket.com/albums/ss34/rottenleonard/press%20die/HPIM4016-1.jpg

[whateg01]

Looks like you are getting there. When things under pressure make funny noises, it's a good time to quickly get out of the way.

A couple of things...

The bolts holding your upper beams to the uprights are probably fine. However, I see that you don't have them "configured" right. You really should have tapered washers between the bolt head and the channel flange. The way you have the bolts now, the bolt head is loaded entirely on one side. If you do run a bolt all the way through from front to back, be sure to use a spacer in the middle so that there is something solid to tighten the bolts against.

In a situation like this, where any deflection in the lower beam can cause it to push the vertical supports apart, you should probably bolt the pieces together, just like you have done at the top. For what you are doing, I suspect that the channel you have is probably sufficient. If you decide to change the uprights, consider the cross-sectional area of what you are replacing with that of what it is being replaced with. It looks like you are using 4" channel, probably 5.4#, which has a cross-sectional area of 1.59". The 2x4 tubing will accomplish that, but it makes it difficult to support the walls of the tubing when running the bolts all the way through.

Dave

[NewOCork]

try

http://www.rockcrawler.com/techreports/fasteners/index.asp

or do a Google search on

shear strength steel bolts

but remember that for multiple bolts to work effectively all holes must be evenly loaded and the hole and bolt diameter should be very close. A single bolt misaligned could be taking up the full load and remember no shear load on the threads.

Corky

[DYCE]

Instead of bolting I would weld the uprights to the beams. It would be a solid joint that way. I have a 50 ton Dake press and the top beam is welded to the uprights. I work with scrap all of the time too, so I know what you are going through. If I was you, I would straighten the uprights on the press now, and I would stitch weld the tubing to them. Then I would weld the uprights to the upper beam.

If you shorten the crossbeams it would go a long ways toward stiffening it up too.

[shortbus]

While your press might be fine to experiment with, you should consider making a dedicated press to actually make these parts.

There doesn't need to be so much length between the upper and lower beams. the opening of the die just needs to be enough to remove a finished part. Making it more compact will in effect make it stronger. I would also put the cylinders more centered in the shape of the part.

cary

[rottenleonard]

Well we have made some progress!!

I rebuilt the press frame, and upgraged to grade 8 bolts in the head. as well as 1" cross pins
http://i559.photobucket.com/albums/ss34/rottenleonard/press%20die/HPIM4027.jpg

Then rebuilt the female protion of the die completely. This time I used 3/8 plate and then had 1/8 plate cnc'd for the perimiter step, followed by milling 1/4" slots 1/8" deep to hold 1/4" round stock.

http://i559.photobucket.com/albums/ss34/rottenleonard/press%20die/HPIM4032.jpg

http://i559.photobucket.com/albums/ss34/rottenleonard/press%20die/HPIM4034.jpg

I reused the old press die structure for stiffness, and added 1/2" plate under the rams as they were denting the current channel. This allowed it to span any gaps without problems.

The male portion of the die didn't change much other than the slots were burned out a little wider and the placement was changed slightly.

http://i559.photobucket.com/albums/ss34/rottenleonard/press%20die/HPIM4033.jpg

I found that forming the peices in two steps (removing the 1/4" rods on the first step)proved to be very effective, however I did try doing it in all at once and it is very close to working, just lacking a little definition (a lot like myself:D)

http://i559.photobucket.com/albums/ss34/rottenleonard/press%20die/HPIM4035.jpg

http://i559.photobucket.com/albums/ss34/rottenleonard/press%20die/HPIM4036.jpg

I am concidering welding the verticle sides of the press to the upper rails and adding a truss to the top portion to match the lower truss, and then adding two more rams I think this would provide enough power to form the peices in one step. That would provide the potential for 50 tons, any opinions on this?


At any rate thanks everyone for their input. It was just what is needed to see this through.


After I get this all Ironed out I also have a very large louver press to complete!:shock:

[RedBeard66]

Looks Good! glad you got it sorted!