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Jm- 7, 1947.
Filed July 12, 1945
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Patented ‘Jan. 7-, 1947
-> 'vvsuuirso- *sTArEs {PATENT ~ orncs Y
v v 'Jarn‘es'L. Le?er, North Hollywood, Calif; assign
' ‘ ‘or to Bendix Aviation Corporation, South Bend,
1nd,, a’corporation ofQDelawar-e
', Application’ July ‘12, 1945, Serial No. 604,629
‘This invention relates
cit-51) ,
An object of the invention is to provide an in;
‘requiring the development of large forces applied
through relatively short, distances.
There is shown in the diagram a conventional
press I consisting of frame vertical members 2
supporting a table 3 on which a work-piece may
to hydraulic'y'pressesand ,, '
_ ‘is particularly useful in hand-operatedv presses;
expensive, economical press for use in operations
be placed;- and supportin , above the table 3 a
hydraulic ram cylinder bcontaining a piston 5
, having a stem 6 which'ext‘ends through the bot
tom of the cylinder and can be moved toward
the table 3 to bear against a works-piece thereon.
The upper end of theycylinder 44 above the
large movements of the ‘press where’ small forces
are involvedpwhile utilizing high pressure “by; 10 piston 5 is connected ‘to a ?uidline 1,, and the
Another object is to provide aipress that utilizes"
an ordinary source of ‘compressed air‘ for‘e?ecting
' draulic ?uid for the developmentof large forces
acting through only short distances;
/ lower end of the cylinder ‘below the ,piston 5 is
connected, to an air line 8. The upperend of .
the piston is at all times filled with hydraulic ?uid,
, Ordinary‘ hydraulic presses‘ require 'a power
pump of substantial‘ capacity‘ for‘ moving the
hereinafter referred to-as oil;
‘ press at a reasonable speed while at the same time 15
The oil line 1 connects to a control valve I I and
also to the discharge port I2 ‘of a hand pump I3.
‘developing the desired high forces. Because of
the expense of-power-pumping equipment; the use
of hydraulic presses had been limited to situations
. This hand pump comprises a relatively small
' hydraulic press during ?nal movement of the
press, and a ?uid pressure as large as may be
- past a check valve ll; the latter port being. con
nected by a line 20 to the upper- end of a cylinder
diameter. working cylinder I4 containing a piston
I5 adapted to be reciprocated by a handle IS.‘
.where there was a substantial amount of press
'\ work to be done. For manypur'p‘oses, it is only 20' The cylinder I4 is connected to the discharge port
I2 past a check valve I6 and to an inlet port I8
-»\necessary to develop high ?uid pressures‘ in a s
2| and to the valve II. The lower end of cyl
required can be developed with a relatively small
and economical hand pump by making the pump 25 inder‘2I is connected by an air line 22 to the valve
II. 1 Any ordinary source of compressed air 23
a. piston relatively small‘; However, when the pump
piston is made small to develop the desired high
pressure, its volumetric capacity is correspond
:is connected. by a line“ to the valve I I.
The cylinder 2| contains a ?oating piston 25
which servesto maintain oil in thelupper end of
of time to move the press platen into position 30 the cylinder separated from air'in the lower part.
‘ The systemdescribed operates as follows:
where it bears against the work-piece.
When it is desired to elevate the piston 5 of
I ,1 accordance with the present inv 'ntion, I
the rain, the valve II is rocked clockwise into
pro ide a press that is capable of develoriing high
the dotteddine position labeled “Up.” This con
forces and, at the same time, is capableof rapid
nects the line 24 from the pressure air supply to
movement up to the point where the ‘ gh force
the line 8 leading to the lower end of the ram
must be generated, by providing a sma 1 capacity
cylinder so that pressure of the compressed air,
high pressure hand pump, in combination with
,lngly reduced so that it may require a great deal
is applied to raise the ram piston. At the same
time, oil in the upper end of. the ram cylinder
46 ?ows out through the line ‘I and through the
valve I I to the line 20 and into the upper end
_ that only aisingle ram is employed on the press
of the displacement cylinder 2|. This moves the
and only hydraulic, ?uid is introducedl'i/nto the
piston 25 downwardly, and the air in the lower
working chamber of} the press ram, the ?uid being
end of cylinder 2| is exhausted to atmosphere
circulated to and from the‘ ram by {air Ipressure
during rapid movement of the-press to engage and 45 through line 22, valve II and an exhaust port
21 in the valve.
/disengage a work-piece.
When ‘it is desired to lower the piston 5 of I
The manner in w ich the foregoing objects are
the ram, the control valve II is rocked counter
attained, together, ith other more speci?c ob
clockwise into'the dotted line positionmarked
I jects and features" of the invention, will be ap
parent from the following detailed description of 50 "Down.’? In this position, it admits pressure air
from line 24 through line 22 to the lower end of
a preferred embodiment of the invention which
the displacement cylinder 2|, forcingv the piston
refers to the drawing.
25 upwardly to displace oil from the upper end
The single ?gure of the drawing is a schematic
of the cylinder through the line 20, and a check
diagram of a system in accordance withrthp in
valve 28 and the line ‘I into the upper end of the
means utilizing an ordinary source of compressed
air for moving the press rapidly so long as only
low forces are involved. The arrangement-is such
ram cylinder. At the same time, the lower end
of the ram cylinder is connected through line,
8 and valve II to the exhaust port 21, so that
tioned can'be made while still utilizing the in
vention, which is to be limited only to the extent ,
set forth in the appended claim.
air pressure forces oil into the upper end of
the ram cylinder to move the piston 5 down.
Since the air supply usually has a. relatively low
pressure, less than 100 p. s. i., no great force is
A hydraulic press comprising: a ram cylinder
containing a piston adapted to be reciprocated in
one direction to press a ‘work-piece. and in the
developed by the ram after the‘piston- rod6
opposite direction to releasethework-piece, said
has contacted a work-piece positioned in'the f ram cylinder having a liquid opening in one end
press. However, the operator can thereafter build 10 for receiving liquid to move the piston in said one
up the pressure in the upper end of the ram
directionLand an air opening in the other end,
a source of compressed air under medium pres
cylinder to any desired value by reciprocating the
handle l6 of the hand pump. On each outward
stroke of the piston I5, it draws in oil from the
sure, aclosed reservoir for hydraulic liquid and
upper end of cylinder 2| through the pipe 20 past '
the inlet check valve H, and on each inward"
air and having aliquid opening and an air open
ing, a‘high~pressure, low volumetric capacity
pump having an inlet opening and an outlet open
ing, said pump being adapted to develop pressures
much greater than the pressure of said air source,
end of the ram cylinder.
The operator can leave the valve ‘II in the 20 check valve means interconnecting said liquid
openings of said ram cylinder and reservoir for
~‘Down” position or return it to “Neutral” posi
permittingv?ow from said reservoir to'the ram
tion, and the ‘hand pump will be equallye?‘ec
stroke forces such oil past the outlet check ‘valve "
l6 and directly through the line 1 into the upper
After the pressing operation has been com
cylinder, while preventing reverse flow,.a control
valve having ?rst,vsecond, and third position'sand
pleted, the operator can again raise the rampis 25 connections extending from said ram cylinder,
said air source, said reservoir,v ands'aid pump to
ton and piston rod to disengage the work-piece
said valve; said valve when in said ?rst position
by moving the control valve ll intothe ~“Up”
connecting the liquid opening of said reservoir to
theliquidopening of said .ram, connecting said
Although a freely ?oating piston 25' has been
air source to the air opening ofv the ram cylinder,
shown in the displacement cylinder I2, its pres
ence may not be necessary in all instances. If the
piston 25 is eliminated, the oil and air connections
30' randconnecting
the air opening ofsaid reservoir
to atmosphere, whereby said ram :piston is moved
in said other‘direction and liquid in the ram
cylinder is returned to said reservoir; said valve
‘should be reversed, i. e., the oil line!!! should be
connectedlto the bottom of cylinder 2|, and the
air line 22 should beconnected to the top of the 35 » when in said second positionconnecting said air
source to the air opening,v of- said reservoir, and
cylinder. It is usually desirable to provide ‘a
connecting the airopening of said ram cylinder to
barrier between ‘the air and the oil within the dis
placement cylinder to prevent mixing of the air ' exhaust, whereby-liquid is displaced from said
It is commonvprac
tice in accumulators for hydraulic systems to em
' reservoir, through said check‘ valve means into
or a ?exible bladder to prevent mixing of the
oil and the air, and a flexible diaphragm or
,said third position, connecting. the air openings
- in the oil under pressure.
40 ,theram cylinder to move the ram piston in said
ploy either a solid piston or a ?exible diaphragm '
one direction withllow force; said valve, when in
of said ram cylinder and reservoir to exhaust;
, and means connecting the liquid opening of the
bladder may be employed in place of the ?oat
ing piston 25 if desired. In such instances, it is 45 ram cylinder to the outlet or the pump, and con
not necessary that the displacement reservoir be
necting the liquid opening of the reservoir to the
in a form of a cylinder, and it may conveniently
inlet of the pump, whereby actuation of the pump
forces liquid into said liquid opening‘otthe ram
be in the‘form of a sphere, similar to conven
tional hydraulic accumulators.
cylinder to develop ‘high force on the piston there
Although for the purpose of explaining the in 50 in.
vention, a speci?c embodiment has been de
scribed, various departures other than those men
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