Improvements in Valves for Hydraulic Presses.
Year: 1897

page_text: Date of Application, 14th Sept., 1897
Complete Specification Left, 6th June, 1898-Accepted, 9th July, 1898
PROVISIONAL SPECIFICATION.
Improvements in Valves for Hydraulic Presses.
I, DOUGLAS VICKERS, a Managing Director of Vickers Sons & Co. Ltd.,
Sheffield, do hereby declare the nature of this invention to be as follows:-
This invention relates to an arrangement of valves for hydraulic presses, such
that great speed of working can be obtained with less engine power than is usually
required. It is applicable to presses in which the pressure is supplied from pumps
capable of working to comparatively high pressures, while the power required
for lifting or retracting the ram is supplied from another system, such as the
hydraulic service supply under some pressure such as 1,000 lbs. per square inch.
Generally under these circumstances the cylinders for lifting or retracting are
always in communication with the service supply, and the pumping engines are
always at work forcing water either into the cylinder of the press, or through
a bye-pass valve to the suction. The working of the press is thus controlled by
this valve, the ram pressing down when the valve is closed and being retracted
when it is open.
This valve is usually worked by a hydraulic ram acted on by
the service pressure. In order to get quick working with this arrangement of
valves the pumping engines have to be very large, for they have to act against
the pressure in the retracting cylinders during the first portion of every working
stroke.
According to my invention, I interpose between the service pipe and the retract-
ing cylinders an inlet valve and a small outlet valve; and I work the bye-pass
valve mentioned above, by means of a hydraulic cylinder communicating with the
retracting cylinders, so that the valve is held open by the pressure in the retract-
ing cylinders, but as soon as that pressure is taken off a counter-weight or ram
subject to hydraulic pressure closes the valve, thus causing all the water from
the pumping engines to pass to the cylinder of the press.
The cycle of operations is as follows:-
(1) The press being at rest with its ram supported by the pressure in the
retracting cylinders both the inlet and outlet valves of these cylinders are closed,
the pressure in the retracting cylinders being that due to the weight of the main
ram and parts connected to it. The bye-pass valve is open, the water discharged
from the pumps passing back to their suction.
(2) When the press is to be put in action the outlet valve of the retracting
cylinders is opened allowing the ram of the press to descend at a speed depending
upon the area of the outlet valve. During this descent the pressure in the retract-
ing cylinders is still maintained, and the bye-pass valve therefore remains open,
water passing to the press cylinder both from the discharge and suction of the
pumps.
:
(3) When the press ram has descended until the work is reached the pressure
in the retracting cylinders is relieved and the bye-pass valve is immediately closed.
The water from the pumps passes to the press cylinder forcing down its ram.
(4) When this has moved as far as required, the outlet valve is closed and the
inlet valve of the retracting cylinders is opened whereupon the pressure in these

page_text: cylinders at once rises, opening the bye-pass valve, and then the press ram rises
as far as is desired when the inlet valve of the retracting cylinders is closed and
the press ram comes to rest as in (1).
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ABEL & IMRAY,
Agents for the Applicant.
Improvements in Valves for Hydraulic Presses.
I, DOUGLAS VICKERS, a Managing Director of Vickers Sons & Co. Limited,
of Sheffield, do hereby declare the nature of this invention and in what manner the
same is to be performed to be particularly described and ascertained in and by
the following statement:-
This invention relates to an arrangement of valves for hydraulic presses, such
that great speed of working can be obtained with less engine power than is usually
required. It is applicable to presses in which the pressure is supplied from pumps
capable of working to comparatively high pressures, while the power required
for lifting or retracting the ram is supplied from another system, such as the
hydraulic service supply under some pressure such as 1,000 lbs. per square inch.
Generally under these circumstances the cylinders for lifting or retracting are
always in communication with the service supply, and the pumping engines are
always at work forcing water either into the cylinder of the press, or through
a by-pass valve to the suction. The working of the press is thus controlled by
this valve, the ram pressing down when the valve is closed and being retracted
when it is open. This valve is usually worked by a hydraulic ram acted on by
the service pressure. In order to get quick working with this arrangement of
valves the pumping engines have to be very large, for they have to act against
the pressure in the retracting cylinders during the first portion of every working
stroke.
In carrying out my invention I arrange the valves and communications as I
shall describe referring to the accompanying drawings. Figure 1 shows the
general arrangement of the apparatus. Figure 2 is a longitudinal section of the
by-pass valve.
Referring first to Figure 1, A is the accumulator loaded to moderate pressure
and supplied by pump Q. The press P has two, retracting cylinders R R; the
pump E which has its discharge pipe D leading to the by-pass valve B and to the
press P, draws its supply from the suction water reservoir ✗. Between the pipe J,
which may be connected to the ordinary moderate pressure main pipes, or which
may be supplied, as shewn, from a specially provided accumulator A at moderate
pressure, and the retracting cylinders R R I interpose an inlet valve V and an
outlet valve W which valves being small can be operated by hand and I connect
the by-pass valve B to the ram H of a hydraulic cylinder communicating by a
pipe with the retracting cylinders R R so that the valve B is held open by the
pressure in these cylinders, but as soon as that pressure is taken off by opening
the valve W, a ram h subject to hydraulic pressure supplied by a pipe a from the
moderate pressure service mains or from the accumulator A closes the valve B
thus causing all the water from the pump E to pass to the cylinder of the press P.
The by-pass valve B is preferably made as shewn with a passage through it
closed by a small valve b, when the valve rod r is retracted by the pressure acting
on the ram H, the small valve b is first opened relieving the pressure on the main
valve B which is then opened by the farther movement of the rod r.

page_text: The cycle of operations is as follows:
1. The press P being at rest with its ram supported by the pressure in the
retracting cylinders R R both the inlet valve V and the outlet valve W of these
cylinders being closed, the pressure in the retracting cylinders R R is that due
to the weight of the main ram and parts connected to it. The by-pass valve B
is then open, the water discharged from the pump E by the pipe Ď passing back
by the pipes to the suction pipe S.
2. When the press P is to be put in action the outlet valve W is opened allow-
ing the ram P to descend at a speed depending upon the area of the outlet valve W,
which is so regulated that during this descent the pressure in the retracting
cylinders R R is still maintained and the by-pass B therefore remains open, water
passes to the press cylinder P both from the discharge pipe D and also from the
suction pipe S.
3. When the press ram P has descended until the work is reached the weight
of the main ram and parts attached to it is supported on the work and the pressure
in the retracting cylinders R R is relieved, and the by-pass valve B is immediately
closed by the pressure on the ram h. The water from the pump E then passes to
the press cylinder P forcing down its ram.
4. When this has moved as far as required, the outlet valve W is closed and
the inlet valve V of the retracting cylinders R R is opened whereupon the pressure
in the cylinders R R and on the ram H at once rises, opening the by-pass valve B,
and then the press ram P rises as far as is desired when the inlet valve V of the
retracting cylinders R R is closed and the press ram P comes to rest, after which
the action can be repeated.
Instead of a ram h subject to pressure from the accumulator, a weight may be
employed sufficient to close the valve B when the pressure is relieved in the
retracting cylinders R R.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what
claim is:-
In combination with the main and retracting cylinders of a hydraulic press-
valves for the supply and discharge of the retracting cylinders, and a by-pass valve
arranged to direct the water from the pumps either to the press or back to the
suction, this valve being automatically controlled by a ram acted upon by the
pressure in the retracting cylinders in opposition to a weight or another ram
acted upon by uniform hydraulic pressure, substantially as described.
Doted this 6th day of June 1898.
ABEL & IMRAY,
Agents for the Applicant.