[TheForge] 15Ton Press

[Chuck Robinson]

Hey Ed,
----- Original Message -----
From: Ed Fasula <edfasula@yahoo.com>
To: <theforge@mailman.qth.net>
Sent: Saturday, January 05, 2002 8:53 AM
Subject: Re: [TheForge] 15Ton Press


> Hi Chuck,
> I really like how you have the cylinder low but still have the top anvil
> the mover.  The angle of the picture makes it look like you can lift the
> unit off the wheels before the anvils are within 6" of meeting.  Must be
> the angle.  Unfortunately, I can't do this with my cylinder, it's about
32"
> overall.  I think I'm going to do something like the H frame design in the
> book, but with the cylinder on top.  I'll probably have to brace it off
the
> wall to keep it  stable.

When the die blocks touch in the closed position there are still a few
inches of clearance.
A 6" cylinder is an excellent size for most press forging requirements, but
you are either going to have to forge on your knees or the press is going to
have to be extremely tall to accommodate a 32" cylinder.. Steward's cylinder
was pretty long also, so we decided to cut eyes off each end and pin the
cylinder in place with 1/2" pins.
The cut ends of the cylinder and ram butt up against the press during the
power stroke so the pins just hold the cylinder in place during the return
stroke.
You should investigate the cost of cutting your cylinder down to a more
convenient size.
There are  enough advantages to my design  over the cylinder on top that I
wouldn't recommend that route.
>
> By throat do you mean the opening between the rails?  Do you ever wish you
> had more room between them?  I am thinking about 12" but I'm a bit leery.

Yes the throat is the distance between rails. Our presses are 16". Bur you
could go 20" if you wanted to, by welding 6" channel to the outside of all
the 1" x 6" horizontal side plates. The rails don't care how wide the
opening is as long as the side plates are stiff enough not to flex.
>
> I could get a cylinder that's 8" or 10" diameter.  I chose the 6" because
I
> looked at the cost of pump, motor, and a VFD to control the motor and
> convert single to 3 phase.

We use scrounged 3 phase motors and make our own rotary phase converters for
about $70. I don't know anything much about the VFD units, and I'm not clear
on why you need to vary the motor speed in a hydraulic system.

 Everything about doubles and I just felt like
> 35 tons was an awful lot.  But I haven't played with presses before.  How
> limited will I be at if I go with the 6"?
See Above.
>
> I'm not clear how the adjustable pressure dump valve would work.  Would I
> set it to, say 2000 psi and above that it would spill into the
> reservoir?  So it would slow down the ram?  Could I stop the ram at a
given
> pressure?

The gear pumps have a built in dump valve usually set to the manufacturers
max recommended pressure, I wouldn't screw with that one. With an inline
adjustable valve you can set the valve to open at any pressure you like as
long as it is less than the pump setting. This would act as an on off switch
for your ram.
The system only sees pressure when the oil flow is restricted in some
manner.
The pump valve won't change ram speed until the ram limits the oil flow into
it because contacts your work.
If you want to adjust ram or hydraulic motor speed you can also put
controller valves and adjustable flow restrictor valves in the system
between the pump and the driven unit.
Remember a 2 stage pump is really 2 separate pumps; a low pressure hi volume
pump, and a high pressure low volume pump. They are both pumping together to
produce a high volume of oil at low pressure to move your ram rapidly. Once
the ram contacts your work a cut off valve closes around 600-700 psi. and
only the hi pressure pump is supplying the oil. That is why I'm using the C
P pump.The flow is full volume until you reach the maximum pressure.


>
> Now that I realize that a pilot valve won't work with a 2 stage pump, I'm
> re-thinking the roller idea.  Balancing the rollers and ram off the same
> system seems like it could be frustrating.  I've been looking at using an
> electric motor with a big reduction in rpm using a gear box and maybe a
> variable drive shiv.

I sure don't have all the answers. I've got a ways to go before I produce an
operating system.
I've got a lot of ideas and a bunch of salvaged hydraulic components from
the Army Ammo Plant down here. As long as I can stay reasonably healthy.
>
> I'm curious, when you use taper dies do you see a lot of force on your
> lock?  I'm not clear if the 3/8" or the 1" dimension is resisting the
force.

The force needed is minimal. You could hold the dies in place with about 60
lbs of force.
The 1" dimension is used, it has to be big enough to drill the bolt hole
thru.

The most critical thing to remember about hydraulic press operations is that
as long as your work piece is hot and plastic the press dies will move it
easily and the material wont slide on the die faces.
Once the metal is cold ( doesn't show color) it resists the die forces and
some horrendous forces build instantaneously. Unless you can mechanically
contain the work in the die faces (especially with taper dies)you have
essentially loaded a cannon. There are some really horrendous stories about
deadly flying missiles that can easily kill the operator or anyone within
several hundred feet of the press.
Chuck