[TheForge] Hydraulic press questions.

Thu Mar 20 01:41:01 2003

Hey Shannell,
In answer to your questions:
If you look closely at the photos on http://www.photoaccess.com ,of my
"window sash" "H" design, I've addressed several of your questions.
as well as some that you haven't asked.
In my design the cylinder pushes on the bottom of the sash so that the side
loading forces are contained by the frame guides instead of the ram it self.
This minimizes any side loading that tends to accelerate wear on cylinder
seals and packing.
The location of the ram below the dies also minimizes the cylinders exposure
to excessive heat from large work pieces.
Finally  the bottom  mounted cylinder positions the dies at a more natural
working height.
Most cylinders except for welded ones are rebuildable. The easiest ones to
rebuild are tie rod cylinders.
If you have reasonable machining facilities you could shorten and rebuild
larger and longer cylinders that are initially too long for a press.
Pumps on the other hand are less cost effective to rebuild and often not
worth the trouble.
I don't use 2 stage pumps. I lucked out and picked up some surplus 6 GPM
pressure compensated piston pumps, And they work quite well in my press.
If you use an 3 hp motor on a pump designed for 5 hp. it will stall the pump
and burn out the motor, unless you are using a lower rpm motor.

When using the press remember that when the work piece is hot and plastic
the piece deforms and doesn't tend to move.
When working with cold stock, it is a completely different situation and the
work piece becomes a potentially dangerous missile. That can easily maim or
kill you.The best safety device is your brain. Don't misuse the press.
The advantage of the 2 speed pump is actually a disadvantage for me when
working with thin damascus billets because the slower the ram speed, the
longer the dies are in contact with the billet, sucking heat from it. I
usually pre heat my dies when pressing damascus.
If you fabricate simple "L"  shaped brackets with elongated mounting bolt
holes for vertical and horizontal alignment adjustments, you don't need the
bell housing. The lovejoy coupling compensates for any minimal misalignment.
I like the Concept of using tandem cylinders on the press This would allow
you to use bottom dies with openings to facilitate pressing drifts  thru
billets when punching holes such as handle holes in hammer heads. The space
between the cylinders could allow the drifts to fall thru.
If you use 2 cylinders it is critical to use identical hydraulic plumbing to
both cylinders to balance the hydraulic pressure to the cylinders with out
resorting to flow dividers or other balancing valves.
In order to maximize the versatility of the press, I like  a piston travel
length of about 12 " or more.
This  facilitates the use of more varied tooling and/or dies and thicker
billets.
My old press uses a hand control valve, but a foot valve is more functional.
In the monster press I'm working on now, the pump will be controlled by a
electric solenoid valve, actuated by 2 micro switch foot valves.
Chuck

----- Original Message -----
From: "Shannell Sugrue" <[email protected]>
To: <[email protected]>
Sent: Wednesday, March 19, 2003 10:49 PM
Subject: [TheForge] Hydraulic press questions.

> I have thought of a few questions I hope I can remember them all-
> 1. Guides- are they mandatory? Ive seen a few presses on the net that just
> rely on the cylinder to be the guide, if you limit the travel from being
> able to go to the bottom of the cyl will this be enough or is 25+ tonnes
way
> to much force to consider this?
> 2. Are all hydraulic cylinders rebuildable? Id like to save some money
here.
> 3.Does every pump need a bellhousing to mount to the motor? the ones Ive
> priced here did, can you not just mount the two in a way that they mate
ok?
> 4. Is an opening under the bottom die a good idea for pushing tooling etc
> all the way through?
> 5. Anyone using a foot pedal to control the press? Something spring
operated
> so foot off means press rises? is this a good safety idea or does it make
it
> less safe?
> 6. I mentioned this in a previous email
>  " someone suggested using 2 pumps one high flow one high pressure and a
hi
> low valve to shut one out when the pressure rises"
> is this a good or bad idea? it was a little cheaper.
> 7. If I buy a pump that need 5hp and run it from single phase 3 hp would I
> get close to 3/5's the flow/pressure?
> 8. They press photos Ive seen didnt have any sort of guards, seems like a
> good idea to me or will they get in the way too much?
>
> Thanks to anyone who has time to answer any of these questions
>
>
>
>
> _______________________________________________
> http://mailman.qth.net/mailman/listinfo/theforge
> theforge mail list group photo site is
> http://www.photoaccess.com
> Login:  [email protected]
> password:  anvil
> ___________
>
>