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Патент USA US2408380

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oct. 1', 1946.
- '._, F, DAY '
Filed Aug. 7, 1944
3 Sheets-Sheet 2
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Oct'. 1, 1946.
, 2,408,379
3 Sheets-Sheet Z
Filed Aug,` '7, 1944
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Luiher FDay
Patented Oct. 1, 1946
g 8,488,879.
Luther F. Day, Hawthorne, Calif., vassignor to
North American Aviation, Inc.
' 'Application August '1, 1944, serial No. 548,383
l 1 claim." (c1. Y10o-'10)
Fig. 3 illustrates diagrammatically the operat
This invention relates to improvements inA
pneumatic presses and has asits general object
ing circuit;
» Y.
Fig.`4 is a detail oi the valve arrangement taken
on line 4-\-4 of Figs. 1 and 5; and
Fig. 5 is a side elevation partially in section of
toiprovide a press of relatively simple and in-r
expensive construction which is capable of de
livering a rapid succession of strokes having ex-V
treme accuracy of stroke limit. A further object
of the invention is to provide a press which elimi
‘ the valve shown in Fig. 4.
As an example of one form in which the’in
vention maybe embodied, I have shown in the
Vnates the wear and tear lupon the clutch used
drawings a light punch press comprising a frame
in `the conventional flywheel and >crank-type
I having parallel side members provided with
press.v A further „object ‘is to provide vaïpress 10, slide Ways 3*--3’ in which is mounted, for vertical
adapted to deliver a stroke of maximum terminal
reciprocation, a ram 2. Movement »is transmitted
power with' a minimum expenditure of energy in
to the ram 2 by toggle mechanism comprising
the lover-al1 operation o_f the press. lA further
pairs, of toggle arms ||-_-4.' andV 5-5’ pivotally
object »is to provide a press which permits of rapid
joined together by a shaft 8 and pivoted respec
tively at-their remote ends to the ram 2 by trun
nions ‘|--'|’> and to the frame I by a shaft 6. The
shaft 6 is Secured to the arms 4 and journaled
A tool 'la may be supported in
Y in the frame |.
variation in the'speed of operation thereof with
out wasting power and without straining the
y' "
rThe invention contemplates a lm_eumatically '
powered, toggle stroke delivery mechanism type 20 the ramr2 and< adapted to cooperate with a suit
able mating tool mounted on the bed 1b of the
of press and aims particularly to provide a press
of this type which’iscapable of delivering twice
_ Vertical reciprocating movement of the ram 2
as many working strokes >per rcycle of motor op-v
is produced by alternately moving the pivotal
, eration, and which provides for greater accuracy
of stroke and correspondingly more uniform ac 25 joint between the toggle arms ñrst to one side
curacyin the workpiece, than has been possible
and then to theother side of the axis of ram
movement, and for this purpose-I provide a pneu
matic servo motor comprising a cylinder || piv
_oted at |2 to the frame and havingva double act
matic servo motor, so that the working ‘stroke of f 30 ing piston 3| (Fig. 3) to which is fixed a piston
rod l0 linked to the shaft 8 by a cross head 9.
the ram terminates inthe middle rather than
It may be> noted at this point that the stroke of
»at the end of` a movement of the servo motor.
the tool 1a is deliveredr when the piston 3| is
This arrangement produces the double advantage
intermediate the ends of its stroke. In the single
of improving the accuracy and uniformityk of the
length of the ramstroke and'also ldoubles the` stroke type of operation that has previously char
acterized toggle presses of this type, it has been
number of ram strokesper cycle of servo motor
impossible to terminate the piston stroke with
suñicient accuracy at the exact point of on-center
A further object of the invention is to provide
alignment of the toggle arms so as to attain uni
novel and _improved control mechanism for a
formityv of ram stroke. By .moving the toggle
double acting 'servoÃmotoL -wherein Vautomatic 40 through
Yand delivering the ram kstroke
control is derived from theïdevice actuated by " while the center
piston is in full motion, I provide much
inyprior presses of this'> general type. To this
end', the inventioniprovides for'through-center
operation ofthe toggle'mechanism by the pneu
the servo motor.
Another object is to provide a kpress which may
be converted from single stroke to continuous
' greater accuracy andstriking powerin the ram
stroke and at the same time provide for double
45 the number of ram strokes per cycle ofV servo
operation lsimplyfby turning a valve handle.
Another object of the invention is'to provide a
Retracting ymovement of the piston 3| is'ef
pneumatically-powered _press 'which can readily
fected by introducingV air through a feed line 29Y
be synchronized with a cooperating machine such
intovthe chamber 30 formed between the one side
as, for example, an automatic feeding. device.4
of the piston 3| and the cylinder ||. -Extending
Like` reference characters designate similar 5.0 movement of the piston 3| is effected by introduc
parts in the several
ing air under pressure through a line 33 into
the chamber 32 delined between the opposite side
Fig. 1 is a front elevation of the press;
of the piston 3| and the cylinder ||. When air
Fig. 2 is a section taken on the line 2-2 of
55 is being introduced through the line 2,9 into the
motor operation.
Fis. 1;
chamber 3i), air from the chamber 32 is exhausted
through the feed line 33, and vice versa.
For reversing the flow through the lines 25 and
33, I provide a slide valve including a casing 25
having ports 28 and 34 with which the lines 29
and 33 communicate, having -an inlet 25 com
municating with a. source of air under pressure,
and having discharge vents 35 and 42 respec
tively, the former adapted to vent air from the
line 33 while the inlet 26 is delivering air to the
other line 29 and the latter adapted to vent air v
from the line 29 when the inlet 26 is delivering
air to the line 33, Slidably mounted in a bore
50 in the casing 25 is a valve plunger 38` having
spaced valve ports 21 and 35 respectively (each
enlarged at the surface of the plunger so> as to
bridge the space between the inlet 26 and the
ports 23, 34 respectively) the port 21 being adapt
4 .
its function until the next half cycle of operation
of the servo motor has taken place, and the slide
valve continues to function until that half cycle
of operation is completed, the pilot valve being
the while shifted for the next half cycle of op
The invention lends itself readily to syn
chronization with a cooperating machine with
out .change in the above-described mechanism.
All that is necessary in 'order to achieve such
synchronization is to control the pilot valve feed
line I1b from the cooperating machine. For ex
ample, where it is desired to synchronize the
`press with a feeding device such as that shown
in Fig. 3, including a slide 41 operated by any
'suitable source of reciprocating movement (such
. as the crank shaft 48 driven by a motor 49 and
connected to the slide 41 by a pitman 56) it is
only necessary to provide a control valve op
communication between the inlet 26 and the line 20 erated by the slide 41 when the latter has com
29 while the port 35 establishes communication
pleted its cycle of operation, and for rthe purpose
between the line 33 and the vent 35, and the port
of illustrating such a valve, .I have shown a valve
35 being adapted .at the other limit of plunger
including a casing 5I having an oscillatory valve
movement to establish communication between
element 52 therein voperated by an arm 53 which
the inlet 2G and the line 33 while the port '2l 25 in turn is moved in one direction by the slide 41
establishes communication ‘between the line 29
and in the other direction by a spring 54. By
and the vent 42.
connecting the line I1b and a feed line v55 in
On the respective ends of the plunger 38 are
properly spaced relationship to the casing 5|, the
pistons 31 andââl which operate respectively in
valve may be made to cut olf the flow of air under
cylinders 45 and 43 formed in the respective ends 30 pressure to the pilot valve except for a short in
of the casing 25. For moving the slide valve
terval at the limit of retracting movement of the
toward the right as viewed in the drawings, air
slide 41, during which interval the- air may be
is introduced from a line 22 into the cylinder 43
supplied to the pilot valve for a suñicient length
to act against the piston 39 while air behind the
of time to reverse the slide valve. While I have
piston 39 is bled through a vent 44. Simultane 35 shown a power-driven source of movement for
ously, air in the cylinder 45 is vented through the
the slide -41 it is to be understood that the slide
line 2I in response to movement of the piston 31;
41 could, if desired, be operated manually and
and air enters the cylinder 45 through a vent 4I
the . press .would automatically operate in re
to ñll the space behind the piston 31. In» the
spense to the manual operation of the slide. It
movement of the plunger in the opposite direc 40 is also to be understood that while the movement
tion, the flow is reversed.
of thev cooperating machinehas been described,
The flow through the lines 2i and 22 is ccn
for illustrative purposes, as a`reciprocating move
trolled by a pilot valve comprising a cylindrical
ment, that it need not necessarily be that type
casing I5 mounted on the frame I and encircling
of movement but could be any other type, such
one end of the shaft 6 which is oscillated by the r as, vfor example., rotary movement.
upper toggle arms 4. The air lines 2| and »22
The foregoing may be taken as illustrative of
connect respectively with ports I9 and 28 cir
one form in which the invention may be em
cumferentially spaced in the casing I5. The
bodied, it being 'my intention to cover in my
shaft 6 has a central bore I6 which is connected
claim the use of any equivalent arrangement or
toa source of vair under pressure by a fitting I1
threaded into the end of the shaft 6, >a. rotatable
I claim as my invention:
coupling I'Ia, and a feed linellb. A passage I8
In a press, a frame, a ram adapted 'to have
in the shaft 5 delivers air from the bore I6 to the
linear reciprocating movement with -reference to
port IS when the arms 4 are at one limit of their
said frame, a toggle comprising a pair of arms
movement and to the port §24 when the arms 4
-pivotally joined to each other, the ‘remote ends
are at the other limit of their movement."v When
of one of said "arms being -attached to a trunnion
the passage I8 is thus delivering lair to the line
member which is journaled in said frame., the
2~I , the line 22 is vented through a Vent I8‘b in the
remote end of the other arm being vpivoted to said
periphery of the shaft 5, registering with the port
ram,> a double -acting pneumatic 'servo motor
20. Vand opening into the end of the shaft 6. 60
linked to the pivotal joint between sai-d 'armsjair
When the passage I8 is delivering air to the line
circulating means for delivering air 'under pres
22, the line 2i is vented through av vent lila,
sure to one end of said servo motor while eX-y
similar tothe Vent i811 but located in the shaft '
hausting air from the opposite end thereof, and
6 on 'the opposite side Vof the passage VI8 as
means for reversing the ilow in saidV circulating
- means Vat predetermined limits of reciprocating
The pilot valve operates to shift the plunger
movement of said ‘servo motor, comprising a valve
38 from one limit of its movement to the other
having an oscillating valve element >comprising
limit thereof prior to any substantial movement
an extension of saidv »trunnion 'and receiving
of the servo motor piston 3|. With the slide
movement therefromj
valve thus shifted, the pilot valve has completed 70
ed at one limit of plunger movement to establish
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