[TheForge] 15Ton Press

[Ed Fasula]

Hi Chuck,

I heeded Ralph's warnings and have managed to swap my cylinder for a 
shorter one with bigger ports.  It's 28" overall with a 19" cylinder and a 
16" stroke.  6 1/2" bore.  This size should work well with your design 
approach.

One thing I really like is that all forces take a load path to the center 
crossbar.  The load path is short and efficient.  But, as with the other 
designs, I'm concerned about off-center loading.  First thing is, my 
cylinder has a 2 1/2" ram which I think is kind of minimal.  I want to make 
sure the cylinder doesn't take side loading forces.  As you mentioned, it's 
just hard on the seals anyway.  So, I plan to guide the tension bars down 
from the cross bar as far as I can.

What I keep calling the tension bars will actually act like cantilevered 
beams above the cross bar when the dies are loaded off center.  I ran some 
rough numbers and the stress from combined tension and bending (maximum at 
the guides) would max out at about 2" of eccentricity.  This is assuming 
3x3 solid bars and a 82,000# press.  If I use 2x2 bars, the maximum 
eccentricity I can get is only 1/2".

Maybe full load,  fully 1/2" off center is sufficient to cover all the odd 
things someone would throw at it.  Obviously you have had good luck with 
it.  Have you noticed any side sway or any other concerns with eccentric 
loading?  Do your guides seem to be working hard?

Thanks,

Ed


>  Ralph if you are worried about the lateral force resulting from upsetting
>metal stock, you can make the guides 20" long and weld guide bars across the
>front and back bottom faces of the guides. Just make sure that you wrap the
>slide with some shim stock before welding the guides in position. This will
>give you enough clearance to minimize rail friction. I used machined bronze
>bearings for my first press, that used 2" round stock, but I found that it
>was overkill.
>Ed, my design called for using 2 hydraulic cylinders, the main reason being,
>to leave the area below the bottom die open so that I could drive drifts
>completely thru the handle holes in the blade forging hammers I make. I
>didn't make this version yet because I wasn't certain about balancing the
>cylinder force, and the rail throat has to be about 20" to provide enough
>working clearance between cylinders.
>Another idea that Len Landrum had was to make the unit using 3" or 4" heavy
>wall square tubing. It promises to be an inexpensive way to increase the die
>base support and also lighten the weight of the total package.
>Since you are aware of  the pros and cons of the VFD motor option I think
>you should try it. I'm hoping that we all can learn something about VFD
>motors thru your experience. None of us have all the answers.
>Chuck


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