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Патент USA US3033180

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May 8, 1962
H. NORTON ETAL
3,033,170
HYDRAULIC RAM APPARATUS
Filed Sept. 25, 1959
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lNv ENTORS
HENQY Noz-roN
HERBERT V. NorroN
L_EsLxE B. Narren
DoußLAs E NORTON
ATTQQNEYS
May 8, 1962
3,033,170
HA NORTON ETAL
HYDRAULIC RAM APPARATUS
2 Sheets-Sheet 2
Filed Sept. 2_5, 1959
52
59
_L_
lNvENToRS
HENRY NoZTON
HERBERT V. NotzvoN
LESLIE B. NoR'roN
bouc-».As
E.Nosz1'o~
ATTORNEY:
3,033,170
United States Patent O M C@
Patented May 8, 1962
2
1
will allow sufficient iluid to escape to maintain the effec
tive fluid pressure on the ram at the desired value.
ln a further form of the invention providing a further
3,033,170
Henry Norton, Hubert Veare Norton, Leslie Buckingham
HYDRAULIC RAM APPARATUS
range of motions, the simple types of control valve de
Norton, and Douglas Edwin Norton, all of Horley, Eng
land, assignors to Norton Tool Company Limited,
scribed above are replaced by a more elaborate control
unit as described in the present applicants’ U.S. Patent
Horley, England, a company of Great Britain
Filed Sept. 25, 1959, Ser. No. 842,509
Claims priority, application Great Britain Oct. 1, 1958
6 Claims. (Cl. 121-38)
No. 2,980,064 issued April 18, 1961.
The invention may be performed in various ways, and
some speciñc embodiments will -now be described by
10 way of example with reference to the accompanying dia
grammatic drawings, in which:
This invention relates to hydraulic ram apparatus suit
able for numerous applications, for instance, for actuating
machine tools such as hydraulic presses, Shapers and
slotters, power steering gear, power transmission systems,
15
mechanical handling equipment and rock drills.
position;
It is an object of the invention to provide a hydraulic
ram apparatus which is easily controllable to provide a
the approach portion of the Working stroke;
variety of motions without excessive energy losses. Al
though in its basic form the apparatus is unusually simple
the return stroke;
it is capable of elaboration to provide a wider variety
of motions.
Hydraulic ram apparatus according to the present in
vention comprises, in its simplest form, a double acting
FIGURE 1 shows a simple form of hydraulic ram
apparatus embodying the invention, as applied to a hy
draulic press, with the ram stationary in its fully raised
FIGURE 2 shows the apparatus of FIGURE l during
FIGURE 3 shows the apparatus of FIGURE l during
`
FIGURE 4 shows a more elaborate form of appara
tus, during a fast approach portion of the working stroke;
and
FIGURE 5 shows the apparatus of FIGURE 4 during
the working portion of the working stroke.
ram having differential effective areas, a connecting pas
In `all the drawings, identical parts have been given
sage between the two ram chambers containing auto 25
the same reference numerals. It is to be understood that
matic unloader valve means having an open condition
the drawings are highly diagrammatic, with the object
maintained at .above a predetermined pressure in the ram
of illustrating the principles of the invention and the
chamber of smaller effective area to permit flow from
way the various valves and the like operate rather than
this ram chamber to the ram chamber of larger effective
area and adapted to be brought into said open condi 30 the details of design .and construction.
rl`he hydraulic ram apparatus shown in FIGURES 1
tion only on .attainment of a pressure substantially in
to 3 comprises a double acting ram 10 having a cylinder
excess of said predetermined pressure a source of hy
11 and a piston 12. The piston 12 has a piston rod
draulic fluid under pressure (eg. a pump) in permanent
13 provided with a working head 14 which is required to
communication with the ram chamber of smaller effec
tive area, and a control valve communicating with the 35 press with a large force upon a work piece 15 resting on
a base 16. The piston divides the cylinder into an
ram chamber of larger effective `area and operable to
upper chamber 17 and a lower chamber 18. Hydraulic
control release of hydraulic fluid.
fluid for operating the ram is drawn from a reservoir 19
This simple form of the apparatus provides for work
by `a high pressure pump 20. The pump delivers fluid
ing and return strokes of controllable length and dura
tion utilising a single control valve, as will be described 40 through a line 21 into a connecting line or passage 22, 23,
24, 25 which connects the chambers 17 .and 18 and which
in more detail hereinafter.
contains an automatic unloader valve 26. The unloader
The automatic unloader valve may comprise a cylinder
valve 26 comprises a cylinder 27 containing a piston 28
containing a spring-loaded piston of relatively large area
urged downwardly by a spring 29. The piston is pro
controlling an outlet port in the cylinder Wall and carry
ing an inlet closure member which can seat on a seating 45 vided with an inlet closure member 30 which can seat
of smaller .area than the piston and which is exposed to
the Valve' inlet, the piston being exposed to the inlet
only when the closure member is lifted from its seating,
for instance by the application to the closure member of
the said predetermined high pressure.
The automatic unloader valve may be provided with
relief means between the piston and the seating operative
to facilitate re-seating of the inlet closure member by
on an inlet seating 31, and itself controls the outlet port
32 in the wall of the cylinder 27. Communicating with
the said connecting line between the sections 24 and 25
thereof is a line 33 which leads to a control valve 34.
The control valve 34 has a piston 35 provided with a
closure member 36 which can seat on a seating 37, the
piston can be loaded by a spring 3S the force of which.
can `be adjusted by a manual control lever 39. A return
line 40 leads from the control valve 34 to the reservoir 19.
The apparatus works as follows. In the condition
shown in FIGURE 1 the piston 12 has finished a return
A preferred form of the invention provides a fast ap
stroke and is up against a dead stop 41 at the top of the
proach during the working stroke. In this form of the
cylinder 11, and the control valve 34 is in a position in
invention there is a source of hydraulic fluid at low pres
which it permits free flow from the line 33 to the return
sure communicating with the ram chamber of larger
effective area through a non-return valve. In such appa 60 line 40. The iiow from the pump 20 through the con
necting line sections 23 and 24 into the line 33 is suffi
ratus there may be an unloader valve between the supply
cient
to hold the unloader valve 26 open, as will be de
of hydraulic fluid at low pressure and the last men
scribed later. In this condition the iiuid flow is as
tioned non-return valve, to unload the said supply when
indicated by the arrows. When ya working stroke is to
this non-return valve is closed.
be performed the control lever 39 is moved towards the
The control valve is preferably such that the pressure
left as Shown in FlGURE 2 to increase the loading of
at which it opens to permit fluid to escape from the
the spring 38 and close the valve 34. The pressure then
apparatus is a function of the magnitude of a force
rises suñiciently to overcome the resistance of the piston
applied to an acuating member of the valve. Such a
12 so that the latter moves downwardly on the approach
valve enables the working force exerted by the ram on
portion of the working stroke. As the piston 12 de
70
relieving hydraulic fluid which might otherwise be trapped
between the piston and the seating.
its working stroke to be controlled, since when the Work
ing force is being applied by the ram the control valve
scends, ñuid is discharged from the lower chamber 18
and passes freely through the connecting line sections
3,033,170
3
4
22, 23, the open unloader valve 26, and the connecting
with means for ensuring that trapped fluid cannot pre
vent it from seating promptly. In this case the lower
part of the cylinder 27 communicates through a passage
line sections 24, 2S into the upper chamber 17, as shown
by the arrows in FIGURE 2, so that the pump 20 has
61 with one end of a cylinder 62 in which is a piston 63.
The space behind this piston is in communication with
the upper part of the cylinder 17 through a passage 64.
When the unloader valve 26 is nearing its closed position
and has closed the port 32, fluid beneath the piston 28
will not be trapped since it will merely be expelled into
the cylinder 62, the piston 63 being moved to the left
correspondingly, there being in effect a displacement of
fluid from the space of decreasing volume beneath the
only to supply enough fluid to malte up the difference
in the volumes of these chambers.
The operator can
slow down the speed of approach by adjusting the con
trol lever 39 towards the right. At the end of the ap
proach, i.e. when the head 14 meets the workpiece 15,
the pressure will build up as required until the valve 34
re-opens. This re-opening may take place voluntarily by
the operator moving the control lever 39 towards the
right, or automatically when the pressure overcomes the
piston 28 into the space of increasing volume above it.
loading of the spring 38 with the control lever in its left
haud position. In the latter case the maximum working
force will continue to be applied to the work-piece so
long as the control lever remains in the left-hand posi
tion. Movement of the control lever towards the right
progressively eases the working force, that is to say, the
position 0f the lever determines the magnitude of the
working force.
This apparatus works as follows. When the control
lever is moved to the left as shown in FIGURE 4 to ini
tiate the fast approach portion of the working stroke, fluid
To cause the piston 12 to rise on its re- '
turn stroke as shown in FIGURE 3, the control lever 39
is moved fully to the right, to open the valve 34. The
piston 12 can now rise freely, the fluid in the upper
enters the upper ram chamber 17 not only from the
high pressure pump 20 and from the lower ram chamber
18 as shown in FIGURE 2, but also from the low pres
sure pump Sil through the low pressure unloader valve
51, the non-return valve 52 and the line 53. The un
loader valve 51 is so constructed that at the relatively low
pressure needed to move the piston 12 in the approach
portion of its working stroke the valve member 54 re
chamber 17 being discharged freely through the lines 25
and 33, and through the valve 34, and all the delivery 25 mains on its seating. In view of the large volume of ñuid
of the pump 20 passing into the lower chamber 18 so
that there is no flow through the unloader valve 26
which accordingly closes. Since the pump 2G is at all
times in communication with the lower chamber 18 the
supplied to the upper ram chamber 17 from these three
sources, the piston 12 will descend rapidly. When the
piston 12 meets resistance, i.e, when the head 14 touches
the work-piece as shown in FIGURE 5, pressure will
return movement of the piston begins practically instan- 30 rapidly build up. The increase in pressure Will open the
taneously on opening the valve 34. When the piston 12
low pressure unloader valve S1, permitting low pressure
fluid to return to the reservoir through the return line
comes up against the dead stop 41 and can rise no further,
5S, so that the non-return valve S2 and the bleed valve
the pressure in the lines 21, 22 and 23 will rise to a high
60 closes. The low pressure part of the apparatus is now
value, exerting sufiîcient Áforce on the closure member 3G
of the unloader valve to lift it from its seating. As soon 35 isolated from the high pressure part, which continues to
operate in the manner described in relation to FIGURES
as this valve lifts, the pressure is applied to the whole
1 to 3.
under the surface of the piston 28, so that the piston is
raised sufliciently to expose the port 32. The apparatus
What We claim as our invention and desire to secure
by Letters Patent is:
is now back in the condition shown in FIGURE l, so
that the cycle described can be repeated.
1. Hydraulic double acting ram apparatus comprising
40
It is not necessary for the return stroke to continue as
a ram cylinder having a side wall and end Walls, a piston
in said cylinder, a piston rod extending from said piston
far as the dead stop 41, since the return motion can be
checked by moving the control lever 39 to the left to
through one of said end walls, said cylinder, said piston
close the valve 34, whereupon another working stroke
and said piston rod defining a first ram chamber and
begins.
45 a second ram chamber of smaller effective area than said
This apparatus thus provides for working and return
strokes of controllable length and duration utilizing a
iirst ram chamber, connecting passage means between
said first and second ram chambers, automatic pressure
single simple control valve.
sensitive unloader valve means disposed in said eonnect~
The apparatus shown in FIGURES 4 and 5 is intended
ing passage means and having an inlet side connected to
to provide a fast approach, and includes some other re 50 said second ram chamber, said valve means having an
finements. Its basic parts are essentially the same as
open condition maintained at above a predetermined pres
those of the apparatus of` FIGURES 1 to 3, with some
sure in said second ram chamber and a closed condition
additions. In addition to the high pressure pump 20
maintained at below said predetermined pressure, said
there is provided a low pressure pump 5€) which is con
valve means in said open condition permitting ñow of
nected through a low pressure unloader valve 51 and a 55 hydraulic fluid in the direction from said second ram
non-return valve 52 to a line 53 which leads to the upper
chamber to said first ram chamber, and in said closed
ram chamber 17 via the line 25. The low pressure un
position preventing such flow, said valve means being
loader valve S1 has a valve member Se which is urged
adapted to be brought into said open condition only on
towards a seating 55 by a spring 56 and which is pro
the attainment of a high pressure subtsantially in excess
vided with a grooved stem 57 so that when it is lifted 60 of said predetermined pressure applied to said inlet side,
from its seating in a manner to be described, low pres
a source of hydraulic fluid under pressure in permanent
sure fluid can escape from the valve 51 through a return
communication with said second ram chamber, and a
line 58. When the valve member 54 is closed, how
manual control valve operable to control release of hy
ever, low pressure fluid must pass to the non-return valve
draulic fluid and communicating with said first ram cham
52. In order to ensure that the non-return valve 52 is 65 ber.
not prevented from seating promptly by trapped low
2. Hydraulic ram apparatus according to claim l, in
which said automatic unloader valve comprises a cylinder
piston 59 is provided which holds the valve member 54
having an outlet port, an inlet connection to said cylinder,
slightly open whenever the pressure in the line 53 is
a seating adjacent said inlet connection, a piston slidable
greater than the delivery pressure of the low pressure 70 in said cylinder and having a cross-section greater than
pump 50. One side of the piston 59 is exposed to the
the cross-section of said seating, an inlet closure member
pressure fluid when it returns to its closed condition, a
pressure on the outlet side of the non-return valve
through a passage 60, while its other side is exposed to
the delivery pressure of the pump S0 within the valve 51.
carried by said piston in alignment with said seating, a
spring loading said piston towards a position in which
said inlet closure member seats on said seating, said piston
The high pressure unloader valve 26 is `also equipped 75 when said inlet closure member is seated on said seating
3,033,170
5
6
being isolated from said inlet connection, said piston when
second ram chamber and a closed condition maintained
at below said predetermined pressure, said valve means
said inlet closure member is clear of said seating being
in said open condition permitting flow of hydraulic fluid
exposed to said inlet connection through said seating, and
in the direction from said second ram chamber to said
said piston controlling said outlet port.
3. Hydraulic ram apparatus according to claim 2, in tu first ram chamber, and in said closed position preventing
which said automatic unloader valve is provided with re~
lief means, said relief means -being connected to said
cylinder between said piston and said seating, said relief
means being operative to facilitate re-seating of said inlet
such 110W, a source of hydraulic fluid under relatively
high pressure in permanent communication with said
second ram chamber, a control valve operable to control
release of hydraulic -iluid and communicating with said "
closure member.
10 iirst ram chamber, a source of hydraulic iluid under rela
tively low pressure, passage means connecting said source
4, Hydraulic ram apparatus according to claim l in
of low pressure hydraulic ñuid to said yfirst ram cham
which said control valve comprises a manual actuating
ber, anda non-return valve in said last mentioned pas
member, a closure member, and means connecting said
sage means.
actuating member to said closure member to impart to
6. Hydraulic ram apparatus according to claim 5 in
said closure member a closing force which is a function
which there is an unloader Valve in said last mentioned
of the manual force applied to said actuating member.
5. Hydraulic double-acting ram apparatus comprising
a ram cylinder having a side wall and end Walls, a piston
in said cylinder, a piston rod extending from said piston
through one of said end Walls, said cylinder, said piston 20
and said piston rod deñning a first ram chamber and a
second ram chamber of smaller elîective area than said
first ram chamber, connecting passage means between said
iirst and second ram chambers, automatic pressure-sensi
tive valve means disposed in said connecting passage 25
means in pressure communication with said second ram
chamber, said valve means having an open condition
maintained at above a predetermined pressure in said
passage means between said source of low pressure hy
draulic flu-id and said last mentioned non-return valve.
References ‘Cited in the ñle of this patent
UNITED STATES PATENTS
2,381,923
2,645,960
Obstresal ____________ __ Aug. 14, 1945
Hutchinson __________ __ July 21, -1953
2,770,222
Anderson ____________ __ Nov. 13, 1956
828,188
Germany ____________ __ Ian, 17, 195-‘2
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