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Dec. 3, 1946,
H. F. MacMlLLlN 'ETAL
2,411,971
EXTRUSION MACHINE
Filed March ~10, 1943
Armdr
no
INVENTOR
Howmo F. MAcMmm,
BY Pam. c. PococM
ATTORNEY
Patented Dec.- 3,? .1946
' 2,411,971
UNITED? STATES
PATENT OFFICE
2,411,971
EX'I?RUSION MACHINE
Howard F. lilacMlllin, Mount Gilead, and Paul 0.
Pocock, Marlon, Ohio, asalgnors to The By
draulic Development .Corp, Ina, Wilmington,
. DeL, a corporation of Delaware
o
- Application March 10, 194:, Serial No. 478,615;
14 Claims. (Cl. 18-12)
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acting the same will be maintained in a relatively
This invention relates to continuous extru-y
balanced condition.
sion machines for extruding plastic materials. ?
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. Another object of the invention is to provide
An object of the invention is toprovide an ex
trusion ?machine for plastic materials 'having a
an extrusion apparatus wherein the extrusion '
?uid supported thrust bearing for the extrusion '
screw is provided with a hydraulic thrust-bearing
screw of the machine.
_ Another object, of the invention is to provide
an extrusion apparatus ' for plastic material
to absorb the axial thrust of the screw and a
hydraulic motor is arranged axially with the
' thrust bearing and the extrusion screw ior driv
wherein the thrust load of the extrusion screw
is absorbed hydraulically.
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ing the screw.
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It is another object of the invention to pro-v
vide an extrusion apparatus wherein the extru
sion screw is provided with a hydraulic thrust
bearing that is adapted to have pressure applied
Another object of the invention is to provide
an extrusion vapparatus wherein the thrust load
of the extrusion screw is absorbed hydraulically
wherein the hydraulically actuated thrust load ' thereon of a relatively constant value to absorb
absorbing device has pressure applied thereto 1.5 the axial thrust of the screw.
into proportion with the thrust load developed by
the extrusion screw.
It is another object of the invention to pro
vide an extrusion apparatus having a hydraulic
thrust bearing for absorbing the axial thrust of
Another object of the invention is to provide
the extrusion screw wherein the pressure applied
an extrusion apparatus that includes hydraulic
motors, for driving the extrusion screw and a 20 tov the thrust bearing is varied in proportion to
I the? thrust load of the screw as re?ected by the
conveyer means for carrying ?the extruded ma
pressure to or from a hydraulic motor that is
terial that are arranged in a hydraulic system
provided for driving the extrusion screw.
for controlling the speed of operation of the hy
Another object of the invention is to provide
draulic motors relatively constant regardless of
the load imposed upon the. motors.
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It is another object of the invention to pro
vide an extrusion apparatus in accordance with
. the foregoing object wherein hydraulic means is
25 an extrusion machine wherein the speed of ro
tation of the extrusion screw and the speed of 1
the conveyer for carrying the extruded material
from the extrusion- machine are regulatable so
that the conveyor moves the extruded material
provided for absorbing the thrust of the extru
jsion screw that has hydraulic pressure applied 30 'at a slightly greater rate than it is- extruded
thereon in a manner to prevent axial movement
of the extrusion screw? within the extrusion
_ chamber unless the thrust load of the extrusion
screw should exceed a predetermined maximum
thrust.
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It is another object of the invention to provide
an extrusion apparatus for extruding plastic
materials wherein the extrusion screw of the ap-v
paratus? and a? conveyer for removing the ex-?
from the machine by means of the extrusion
screw whereby?the extruded material is elon- .
gated slightly as it leaves the machine to increase
> its tensile strength.
Further objects and advantages will become
apparent from the drawing and the following
description.
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In the drawing:
Figure 1 is a diagrammtic representation of an '
truded material from the apparatus are driven 40 extrusion machine? and a hydraulic system for
operating the same.
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by hydraulic motors that are independently con
Figure 3 is a diagrammatic view of a portionv
trollable as to their independent speeds and
of the mechanism disclosedin Figure 1 showing
which will remain in speed synchronism regard
the hydraulic thrust bearing receiving pressure
less of the load imposed upon the motors, all of
from the back pressure control line that regulates
which are accomplished by? means .of an auto
the .speedpf a hydraulic motor for the machine.
matic balancing hydraulic control system asso
.Figure 3 is a diagrammatic representation of
ciated with the hydraulic motors.
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a portion of the hydraulic system showing the
Another object of the invention is to provide
. manner in which a relatively constant pressure
an extrusion apparatus in accordance with the
foregoing object wherein the axial thrust oi the 50 can be suppliedr?to?the hydraulic thrust bearing ~
by means of an independent? ?uid source.
extrusion screw is absorbed hydraulically and
Figure 4 is a diagrammatic representation of
wherein the thrust absorbing hydraulic means
a portion of the system of the machine illustrate
has pressure applied thereto as determined by
ing the manner in which the ?uid pressure to the
the thrust load produced by the extrusion screw
so that the thrust load and the force counter 55 hydraulic thrust hearing from an independent
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source can be changed in response to changes in
cylinder l0. ? The ?ights 33 on the rearportion
back pressure of the ?uid motor for driving the
of the screw 30, adjacent the feed opening 2c
are relatively coarse while the ?ights 34 within
the forward end of the cylinder ill have their
r extension screw.
The extrusion machine of this invention is par
ticularly adapted for extruding plastic materials
pitch decreased so as to provide a more positive
drive of the plastic material through the extru
sion cylinder and compacting vof the material
while?passin'g through the heating ?zone that is
of a type that are fed into the machine in? a
granular or powdered form and are heated and
plasticized within the machine during forward
movement ofthe plastic material through the
heated by the heating chamber 2i.
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machine as produced by an ?extrusion screw so 10' The extrusion screw 30 is provided with a shaft
that the plasticized material can be forced
35 that extends through the rear wall 36 'of the
through a nozzle or die to form the material into a
extrusion cylinder ill. This shaft 35 passes
through a hydraulic motor Ml that is adapted to
any desired shape upon passage through the die.
Suitable conveying means is provided for carry
ing the extruded material away fromthe extru
sion die as it is discharged therefrom. Any of the
drive the shaft? 35 vand thus rotate the screw 36
for feeding plastic material through the extru
sion cylinder. The? driving mechanism of the
hydraulic motor 40 is drivingly connected to the
usual means for supporting the hot plastic matee '
rial as it leaves the extrusion machine can be
provided, such as air jets, for ?oating? the ex
; shaft 35 by means of a keyadapted to ride in the
keyway 44 provided in the shaft 35, whereby the
shaft 35 can move axially through the motor db
truded material until it has cooled sufficiently to _
permit it to be supported upon a conveying appa
and thereby permit a limited amount of axial '
ratus.
As the quantity of material vextruded by a ma-. ?
chineincreases, and machines of larger capacity
arelmade, the axial thrust load produced by the 25
extrusion? screw becomes extremely large so that
considerable trouble is encountered'with the use
of conventional mechanical thrust bearings for
absorbing the axial thrustof the extrusion screw.
movement of the extrusion screw 30 in the ex
trusion cylinder l0. While the hydraulic motor
40 has been described as being constructed and
arranged in a manner for axial mountingon the
shaft 35, yet it is to be understood that any con
ventional hydraulic motor can be used to drive
the shaft 35 either through a suitable gear re
duction mechanism or belt system. Theend of
This invention, therefore, provides a hydraulic 30 the shaft 35 carries a- piston 42 that slidably
thrust bearing for the extrusion screw, thereby
engages the internal bore 43 of a cylinder 44 to
provide a hydraulic thrust bearing for the screw
supportingthe screw upon a column? of ?uid
maintained under pressure which can either be
30.
constant or changing in accordance with varying
The hydraulic thrust bearing, generally desig
conditions desired in the hydraulic system asso 35 nated by the numeral 45, is arranged with the
ciated with the extrusion machine.
cylinder 44 thereof coaxially with the shaft 35.
The apparatus of this invention is diagram
The front wall 46 of the cylinder 44 carries a
matically illustrated in Figure 1 wherein the ma
bearing member 41, which can be of anyv antifric
chine is disclosed as consisting of an extrusion
. tion bearing construction against? which a shoul
cylinder [0 having an internal bore ii that is of 40 der 48 provided on the piston 42 is adapted to
rest. A packing gland 49 is provided in the front
constant diameter., The forward end 82 of the
cylinder in is provided with a tapered bore 85
wall 46 around the shaft 45 to prevent leakage of
whichcconverges toward a nozzle ori?ce 54 which
?uid around the shaft 45. The opposite end of
connects with a die .65. The cross sectional open
the cylinder 44 is closed by means of a plate 50.
ing-of the ori?ce or channel i 6 in the die l5 deter 45
To carry the extruded member l1 away from
mines the cross sectional contour of the extruded
the extrusion cylinder i0 there is provided a
piece H that emerges from the die l5.
'conveyer 5| that is driven by means of a hydrau
The cylinder it is provided with a hopper I8
lic motor 52, the motor 52 being of any conven
for receiving granular plastic material 89, or the
tional construction that is suitably adapted for
material may be in powdered form, which dis-A 50 the purpose. Of course,- it is to be understood
charges through a feed opening 20 provided in
that the machine shown in Figure 1 is diagram
the cylinder? ID to. conduct the plastic material
matically represented and that suitable air jets
into the cylinder bore ll of thecylinder l0.
will be provided around the extruded member I?
?Heating chambers 2i are provided in the cyl
to initially suspend the same upon leaving the ex
inder i0 around the portion thereof that con
trusion die IS.
tains the uniform diameter bore H for heating
The hydraulic system for the extrusion ma
granular plastic material that is conducted
chine heretofore described includes a pump 60
through the bore H from the feed opening 20. If
for supplying ?uid under pressure to the hydrau
desired, the heating chamber 22 can be provided
lic motors 52 and 40. The pump 60 is of the var
in the tapered front end portion l2 of the cylinder 60 iable delivery type of any conventional construc
I0 and the die i5 can have a heating chamber
tion. As illustrated in this invention the pump
23. The heating chambers 2|, 22 and 23 are pro- I
60 is adapted to be placed on-stroke by means of
a spring 6| that is opposed by a piston 62 work
vided with suitable inlet conduits 24, 2.5 and 25
ing within a cylinder 63, the piston 62 having a
and suitable ?uid discharge conduits 21', 28 and
29, respectively.
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65 plunger 64 that engages the pump mechanism
tending to place the pump off-stroke, the piston
?An extrusion screw 30 is positioned within the
extrusion cylinder ID. This screw consists of a
62 moving in a left-hand direction as viewed in
core portion 3i that increases in diameter from,
Figure 1. Therefore, the pump vGil is normally
the-feed opening 20 of the extrusion machine to
held on?str0ke by means of the spring GI and is
only moved off-stroke, when pressure is placed
ward the front end of the cylinder l0 and a core
within the chamber 65 provided between the pis
portion 32 in the tapered front end l2~ of the cyl
inder III that decreases in diameter toward'the
front end of the machine?so that the wall of the
ton 62 and the cylinder 63.
The pump 60 is provided with a suction con
core portion 32 is uniformly spaced from the bore
duit 66 that connects to a. supply reservoir 61.
l3 in the front end section I2 of the extrusion 75 The pump 60 discharges through the conduit 68
2,411,971 _
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that has one branch 69 for conducting ?uid un- I
der pressure to the motor 52 and another branch
10 for conducting ?uid under pressure to the mo
tor 40. The discharge conduits ?I! and 12 of the
motors 52 and Mi, respectively, conduct ?uid from h
? these motors to a balancing valve 15.
- The balancing valve 15 consists of a cylinder
16 in which three interconnected piston heads ?l1,
If the pressure in the chamber 91 is just equal
to the axial thrust load developed by the screw
30 then the piston 42 will ?oat upon the liquid in
the chamber 91. It the pressure in the chamber
91 is variedin accordance with the axial thrust
load developed by the screw 30, then regardless
of the thrust load developed by the screw to
there will be no movement of the screw in a right
hand direction, the liquid in the chamber 9i
?l8 and 19 are adapted to reciprocate. The con
duit ?H from the motor 52 communicates with a 10 maintaining the screw in its extreme leftward
position, as shown in Figure 1. When the Dres
recess 80 provided in the wall of the balancing
sure is maintained constant in the chamber 9?
. valve 15 that is adapted to be covered and un
then the hydraulic thrust bearing operates as an
covered by means of the piston head ?I9. The
overload, or safety device, because if the thrust
recess 80, therefore, provides a variable restric
tion between the conduit ?H and the chamber 8| 15 load produced by the screw 30 in a right-hand
direction is greater than the hydraulic force urg
disposed between the piston heads 19 and ?it of
ing the piston 42 in a left-hand direction, the screw
the balancing ?valve ?I5. The chamber 86 com
30 will move against the pressure in the chamber
municateswith a conduit 82 in which there is
91 to relieve the overload thrust developed by the
placed a restriction or choke valve 84, the conduit
82 connecting with a conduit 83 that communi
As illustrated in Figure ,1, the pressure in the ?
cates with the supply reservoir 67. The conduit
- chamber 91 is the same pressure that exists in
82 is also connected with a conduit 85 that ex
the pressure line 10 from? the pump, this pres
tends into communication with the chamber 65
sure varying in accordance with the torque e?ort
provided in the cylinder 63 on the pump 60,
required by the motor 40 so that the pressure in
whereby the chamber 55 is responsive to the pres
the chamber 9] will vary and produce a force
sure existing in the chamber 8| in the balancing - through the piston 42 that is'proportional to the
valve 15. A branch conduit 86 connects the con
torque eil?ort required by the motor to as re
duit 85 with a chamber, 8'! provided adjacent the
?ected by the operation oi the extrusion screw 39.
left-hand face of the piston head 19. '
The speed of the motors 50 and 52 are inde
30
- The discharge conduit 12 of the hydraulic mo
pendently controllable through means of the bal
tor 40 is connected to a recess 90' provided in the
ancing valve and the chokes 84 and 93 so that,
balancing valve 75 that is adapted to be covered
and uncovered by the piston head ?I? to thereby ? they can operate the conveyer El and the extru
sion screw 30 at any desired speed, in a manner
provide a variable restriction between the con
to be hereinafter described, and will operate in
duit 1.2 and the chamber 8i provided between the
synchronism once the speed relationship has been
piston head TI and the piston head ?it of the bal
screw.
ancing valve 15. The chamber 9! communicates
, with the return conduit 83 through a conduit 92
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established. It is preferable .that the hydraulic
motor 52 shall operate the conveyer 5| at a speed
slightlygreater than the speed of discharge of
positioned therein. A conduit at connects the 40 the plastic piece I?! from" the die i5 so that when
the plastic piece I?! engages the conveyer there
chamber 95 adjacent the right-hand. face of the
will be a slight stretch or drawing action in the
piston head Tl in the balancing valve ?i5 with the
plastic piece ll? tending to elongate the same and .
conduit 92 ahead of the choke valve 93 so that the
reduce its cross section slightly for orienting the
space 85 will be communicating with the space
having a variable restriction or choke valve 93
9| in the balancing valve 15.
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The hydraulic thrust bearing 45 is connected
to the pressure line it from the pump Eli by means
of the conduit- 96 so that the pressure in the
, ?molecular structure of the plastic material and
, thereby increasing the tensile strength of the ma
terial.
I Operation
chamber 97 of the hydraulic thrust bearing 85
Assuming the extrusion machine to be in full
will be the same pressure as that which exists in, 50 operation; that is the motor 52 is driving the
conveyer 5| , the motor 40 is driving the extrusion
the pressure line is from the pump ea
screw 30, the plastic piece is being forced through
When the extrusion machine is operating and
the hydraulic motor at is driving the extrusion ' the die l5 and the pump 6t is delivering liquid
under pressure through the lines 69 and ?ill to
screw 38 to move the plastic material through the
extrusion cylinder ii! for forcing the material 55 operate the hydraulic motors 52 and �, with
the branch line 96 conveying ?uid pressure to
through the extrusion die i5 there is a large
the chamber 91 of the hydraulic thrust bearing
axial thrust developed by the extrusion screw to
that tends to move the screw in a right-hand ' 4'5. With these conditions in eiiect the piston 152
' of the hydraulic thrust bearing as will be posi
direction. This axial thrust load becomes? ex
tremely large when moving large quantities of 60 tioned with the shoulder t8 thereof in engage
ment with the bearing 57. With a maximum'nor
material through the extrusion cylinder id, and
varies somewhat due to any variance in density
oi? the granular material that is fed into the,
?ights 33 of the extrusion screw ?it and by the
mal thrust produced by the extrusion screw Sil
opposing the ?uid pressure in the chamber 91, the
bearing d1 need only to support a thrust load
plasticity of the plastic material when it is in 85, in the left-hand direction that is equal to the
differential between the opposedvthrusts devel
the forward end 62 of the extrusion cylinder it.
The ?uid pressure in the chamber �7 of the
hydraulic thrust bearing 65 therefore absorbs this
axial thrust of the extrusion screw 3%, the col
oped by the screw t? and the piston 182 to main- ?
. tain the screw 30 in a predetermined position in
the extrusion cylinder it and thereby maintain
70 the cross sectional area between the core 32 and
the bore it of the cylinder til relatively constant
sure applied thereto balancing the thrust load of
to obtain uniform discharge or plastic material
screw 3h regardless of what this load may be.
through the extrusion die ie by maintaining
It will readily be seen that as long as pressure
constant pressure thereon due to constant rota
stands in the chamber at that movement of the
umn of liquid in. the chamber @?i and the pres
screw lit in? a rie?htnhand direction is ?resisted.
tion of? the screw 30 and the constancy of the
earners
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cross sectional area between the core portion 32
and the bore i3.
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The balancing valve it maintains constancy
of speed of operation of the hydraulic motors 52
and ill, as well as? maintaining them in synchrow
nization after their speed of operation has been
set.
Assuming that the torque load on the motor 52 '
is increased, there will be a decrease of pressure
?uid through the resistance formed by the recess
W, thereby reducing the total resistance in the
control system for the motor 40 and increasing its
speed of operation.
From the foregoing description it will be noticed
that when the torque load on the motor 40 is in
creased that the pressure in the line 10 is in
creased to overcome the increased torque load.
This increased
pressure will be transmitted
in the conduit ?H and thus in the chamber 8!, the 10 through the line 95 into the chamber 81 of the
hydraulic thrust bearing 45 so that whenever the
conduit 82, the'conduit 85?, the chamber 55 and
the chamber 8?. This reduction in pressure in
torque load is increased upon the motor 45 there
chamber 87! of thebalancing valve '15 permits the
will be an increased pressure in the chamber 51
urging the piston 52 of the thrust bearing 45 in a
valve member within the valve 15 to move in a
left-hand direction so that the head ?#9 reduces 15 leftward direction to overcome the increased
thrust produced by the extrusion screw 30 that
the restriction across the recess 80. Simultane=
ously, an increase of restriction is produced across
has resulted from increased friction of movement
of thejplastic material through the extrusion
the recess 90 since the piston head TI is also mov
cylinder lo. Therefore, the thrust load of the ing in a left-hand direction. This increased re
striction across the recess 95 would tend to slow 20 extrusion screw 30 will always be balanced by
the'hydraulic thrust bearing 45.
down the motor 40 at this time. However, simul
taneously with the previous action the pump 60
The system as heretofore described in Figure 1
was permitted to go on stroke because the pres
maintains a balanced opposed thrust condition
between the extrusion screw ?30 and the thrust
sure in the chamber 65 is reduced thereby in
creasing the delivery from the pump 50 for sup 25 bearing 45 whereby the bearing 45 can oppose
plying additional ?uid under pressure to the mo
any thrust load developed by the extrusion screw
tors '52 and 40. The additional pressure is uti- '
30 and prevent the screw 30 from moving rela
lized by the motor 52 in maintaining the speed
tively'to the extrusion cylinder Ill so that there
of the motor constant to overcome the increased will always be a relatively constant pressure
?torque load that has been imposed thereon while 30 maintained upon the plastic material passing
the increased pressure passing through the pumpv
through?the bore I3 of the extrusion cylinder ill
and therefore maintain constancy of flow of ma
terial through the extrusion die l5.
ing its speed of operation.
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Under certain? conditions it may be desirable
Assuming now the torque load is increased on
that the thrust bearing 45 shall be used as an
the pump 40. Under this circumstance pressure
overload or safety feature to prevent overloading
in the conduit 12 falls which permits a drop in
of the extrusion screw 30. To provide for this ?
pressure in the chamber SI of the balancing valve
contingency the system as illustrated in Figure
15 on the right-hand side of the piston head 11,
2 can be used. In this system the hydraulic
whereby the valve member in the balancing valve 40 thrust bearing 45 has the chamber 91a thereof
- '15 moves in av right-hand direction to decrease
connected to the conduit 94 of the balancing valve
the restriction through the recess 90. Simulta
15 by means of a conduit 98; This conduit 88
neously, the piston head 19 is moved in a right
therefore provides communication between the
constant pressure conduit 94 and the chamber
hand direction to increase the resistance across
the recess 80 thereby producing a drop in pres
_9?|a, so that the relatively constant pressure in
sure in the chamber 8! and resulting in a drop
the chamber 9| of the balancing valve 15 is com
in pressure in the chamber 55 of the control cyl~
municated to the chamber 91a. It will thus be
inder 63 for the pump 50. The pump 60 thereby
seen that with a relatively constant pressure pro
? moves toward its on-stroke position again deliv
vided in the chamber 91a of the hydraulic thrust
ering an increased quantity of ?uid under pres 50 bearing 45 that when the ?axial thrust load of the
sure to the motors 52 and til. Since the motor 40
extrusion screw 30 is greater than the hydraulic
force developed by the piston 42a of the hydraulic
is under an increased torque load the increased
pressure will be dissipated through the motor and
thrust bearing \45 that the piston 42a will move in
a rightward direction against pressure existing
the speed will remain constant, while in the case
of motor 52 the increased pressure will be dissi
in the chamber 91a to relieve the thrust produced
40 is dissipated across the increased resistance in?
the recess 90 to prevent this pump from increas~
pated through the increased resistance through
by the extrusion screw 30. As it is only a momen
the recess 80 so that its speed will not be changed
by this increased pressure.
In order to change the speed of the motor 52
tary overload there will be no further movement
of the extrusion screw 30. Any condition of un
derload of the extrusion screw 30 will permit the
relative to the motor 40 the choke valve 84 is op 60 screw to move in a leftward direction, as viewed
erated to reduce the restriction through the same.
in Figure 1, so that the screw 30 therefore ?oats
This results in a lowering of the pressure in the
upon the constant pressure maintained in the
conduit 82 ?for shifting the balancing valve 15 in
chamber 91a.
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a manner heretofore referred to, to permit ?an
If the overload condition is a continuous over
increased ?ow of ?uid through the motor 52, the 65 load, then the thrust of the screw 30 will force
total resistance through the motor control system
the piston 42a against the constant pressure in
for the motor 52 being less than it was previously
the chamber 91a until the screw strikes the rear
so that there will be an increased ?uid ??ow and
of the extrusion chamber or the piston 42a of the
thereby an increased speed of operation of the
hydraulic thrust bearing bottoms. 0n the other
motor 52.
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70 hand, if there is a continuous underload of the
To increase the speed of operation of the motor
extrusion screw tending to relieve the thrust
40 the choke valve 93 is operated to reduce the
, load, such as an increased ?uidity of the plastic
restriction across the same and thereby reduce the
material, then the piston 42a of the hydraulic
pressure in the conduit 92 and cause the balanc
thrust bearing 45 will bottom upon the bearing
ing valve 15 to shift and increase the flow of 75 41 and prevent the extrusion screw 35 from ad
3,411,911
vancing completely into the end of the extrusion
chamber.
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the extrusion screw during the initial operatic
of the machine when it is starting on a new cycle
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of operation. '
In Figure 3 there isishowiranother arrange
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While the apparatus disclosed anddescribed
ment whereby constant pressure can be main
herein constitutes apreferred form of the'inven- _
tained in the chamber 01b of the hydraulic thrust
bearing 45b. In this arrangement an independ
ent variable delivery pump I00 is provided for
delivering-??uid under pressure through the con
tion, yet it is to be understood that the appa
ratus is capable of considerable. alteration with- _
.out departing from the spirit of the invention,
and that all such modi?cations as fall within the
duit -IOI into the chamber 011) of the hydraulic
thrust bearing 45b. The variable delivery pump 10 scope of the appended claims are intended toYbe
I00 is provided with a pressure control I02 that
communicates with the discharge conduit IOI of,
the pump I00 through the conduit I03 whereby
included herein.
the discharge pressure of the pump I00 is main
Patent is:
tained relatively constant. Such constant pres
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vHaving thus fully described our invention what
we claim as new and desire to secure by Letters
15
sure controls for variable delivery pumps are
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1. An extrusion machine consisting of an ex
trusion cylinder, an extrusion screw rotatableiin
said cylinder, a liquid chamber co-axial with said
extrusion screw, a piston in said chamber in co
well-known and therefore it is not believed that,
additional description of v?such controls is neces
operative engagement? with said extrusion screw,
sary. The operation of the hydraulic thrust
bearing 45 is the same in this instance as that 20 thrust bearing means associated with said ex
trusion screw for absorbing any forwardly di
heretofore described with regard to the disclosure
rected ?thrust of the screw and positioning the
' of the apparatus as shown in Figure 2, the pres
same in its normally operating forward posi
sure of the ?uid being maintained constant inv the
tion in said extrusion cylinder, a ?uid circuit for ,
chamber 91a of the device, as shown in Figure 2.
In Figure 4 there is shown a slightly modi?ed? 25 supplying liquid under pressure to said- chamber
for acting against said piston to maintain said _
arrangement wherein an independent pressure
extrusion screw in its forwardmost position and
source is made responsive to the discharge pres
to absorb all rearwardly directed axial thrust of
sure from the hydraulic motor ,40 so that the in
said extrusion screw, and means in said ?uid?
dependent pressure source will vary the pressure .
of the ?uid in the hydraulic thrust bearing 45 ' 30 circuit and responsive to increase and decrease
of torque from said screw for correspondingly in
in accordance with the torque load imposed upon
creasing and decreasing pressure within the cir-'
the hydraulic motor 40' as re?ected by,the dis
cuit and said hydraulic bearing whereby to main;
' charge pressure therefrom. In this arrangement
tain said piston and screw in relatively ?xed po- _
the hydraulic thrust bearing 05 is the same as
that heretofore described with regard to the de
vice disclosed in Figure l and the shoulder 48
of the piston 02 is adapted to engage the bearing
41 to maintain the position of the extrusion screw
sition despite torque changes effecting said screw.
2. An extrusion machine consisting of an ex�
trusion cylinder, an extrusion screw rotatable
in? said cylinder, a liquid chamber co-axial with
said extrusion screw, a piston in said chamber
00 within the extrusion cylinder. An independ
?in cooperative engagement with ?said extrusion
ent variable delivery ?uid pump I05 has the dis
screw, thrust bearing means associated with said
charge side thereof connected to the chamber 01
of the hydraulic thrust bearing 45 by means of i extrusion screw for absorbing any forwardly di
rected thrust of the screw and position the same
a conduit I04, The variable delivery pump has
in its normally operating forward position in said
a conventional control element I06 that is con
extrusion cylinder, a ?uid circuit for supplying
nected to the discharge conduit ?I2 of the?hy
liquid under pressure to said chamber for acting
draulic motor- d0? by means of a conduit I01.
against said'piston to maintain said extrusion
Therefore, the pressure delivered into the conduit
screw in its forwardmost position and to absorb
E04 by the pump I05 is responsive to the pressure
all rearwardly directed axial thrust of said ex
5 existing in the discharge conduit ?I2 of the hy
trusion screw, and means within said circuit and
draulic motor dd so that whenever this ?discharge
?interconnected with said driving means to in�
pressure changes due to a change in the torque
crease and decrease the pressure within said hy
load of the hydraulic motor 80, the pressure in
draulic bearing in response to air increase and
the chamber 9?! will be changed to balance the
decrease in the torque from. said screw for cor
change in thrust of the extrusion screw as re
?ected by the change in torque load on the hy
draulic motor 40. In this arrangement, there
fore, it is possible to provide pressure in the cham
55
respondingly increasing and decreasing pressure
within the circuit and said hydraulic bearing
whereby to maintain said piston and screw in
relatively ?xed position despite torque changes
eifecting said screw, said pressure being supplied
her 91 which is just sufficient to balance the axial '
thrust of the extrusion screw at any time during
the operation of the extrusion machine from the 60 ?to said chamber being maintained at a value that
the force produced by said piston is just slightly
time it begins to operate until a maximum thrust
greater than the axial thrust produced by said
load is developed, It will be understood that dur
ing the initial starting of the equipment that the ' extrusion screw whereby said bearing means only
carries a thrust load that is? determined by the
axial thrust load of the extrusion screw is rela
tively light because the extrusion chamber is 65 differential in force developed by said piston and
said extrusion screw.
not ?lled and material is not being? extruded
3.籄n extrusion machine consisting of an ex
through the extrusion die, ' Therefore, if the pres;
sure in the chamber 0? ?of the hydraulicv thrust ,
trusion cylinder, an extrusion screw, a ?rst hy
draulic motor for driving said? extrusion screw,
bearing 65 is made responsive to the pressure?
in the discharge line from the hydraulic motor 70 a source of variable pressure fluid supply for
said motor, control means actuated by the pres
til-and thus is responsive to the torque load as
sure in the discharge line from said motor to
re?ected by the "axial thrust developed by the'ex
trusion screw that the pressure in the chamber?
07 will be :light and therefore ?Just suiiicient to
balance the light axial thrust load developed by?
regulate the ?uid supplied to said motor to control I
the speed of rotation thereof and-thus control the '
75 speed ofrotation of said screw, conveying means '
2,41 1,971
for carrying extruded material away from said
pressure chamber in said ?uid thrust bearing for
regulating the pressure in said chamber in re
sponse to the discharge pressure from said motor
extrusion cylinder, a second hydraulic motor
means for driving said conveying means, a
variable pressure source of ?uid supply for said
conveying'motor means, and control means actu
ated by the pressure in the discharge line from
said second motor for regulating the ?uid sup
plied through ?said second motor means for there
and thus in response to the load imposed upon
said motor,
7. An extrusion machine consisting of an ex
trusion cylinder, an extrusion screw, a ?uid
motor for driving said extrusion screw, a com
by controlling its speed of operation, said control
pletely hydraulic thrust bearing for said extrusion
means being operably interconnected to operate 10 screw having a pressure chamber therein for
simultaneously upon a drop in pressure in the
solely absorbing the axial thrust of said extrusion
discharge line from either motor and change the
delivery rate of the ?uid supplying means without
screw by the ?uid in said chamber, control means
, for regulating the discharge of ?uid from said
aiiecting the speed operation of either of said
motors.
hydraulic motor having means to change the re
15 sistance to ?uid ?ow from said motor in response
,
4. An extrusion machine consisting of an ex
trusion cylinder, an extrusion screw, a ?rst hy
draulic motor for driving said extrusion screw,
a source of variable pressure ?uid supply for said
motor, control means actuated by the pressure 20
in the discharge line from said motor to regulate
the ?uid supplied to said motor to control the
speed of? rotation thereof and thus control the
speed of rotation of said screw, conveying means
for carrying extruded material away from said 25
extrusion cylinder, a second hydraulic motor
means for driving said conveying means, a
variable pressure source of ?uid supply for said
conveying motor means, and control means. actu
to the load imposed upon said motor for main
taining the speed thereof substantially constant
with a varying pressure on the inlet and discharge
side of said motor, and means for conducting ?uid
from the inlet side of said motor to said pressure
chamber in said hydraulic thrust bearing for
regulating the pressure in said chamber in re
sponse to the inlet pressure to said motor and
thus in response to the load imposed upon said
motor.
~ 8. An extrusion machine consisting of, an ex
trusion cylinder, an extrusion screw rotatable
within said cylinder for feeding plastic material
therethrough, a hydraulic motor operably con
ated by the pressure in the discharge line from 30 nected to said extrusion screw for driving same,
said second motor for regulating the ?uid sup
a variable delivery ?uid source for supplying ?uid
plied through said conveying motor means ,for
under pressure to said motor, a hydraulic thrust
thereby controlling its speed 01' operation, said
bearing for said extrusion screw consisting of a
control means being operably interconnected to
' single acting hydraulic motor for opposing the
? operate simultaneously upon a drop in pressure 35 axial thrust of said extrusion screw, means hy
in the discharge line from either motor and
draulically connecting said single acting motor ?
' change the delivery rate of the ?uid supplying
to said variable delivery ?uid source, andmeans
means without affecting the speed operator of
responding to ?uid pressure variations in said
either of said motors, said conveying means being
?rst motor to change the volume and pressure of
operated by the motor ?means for\the?same at a
the ?uid delivered by said variable delivery source
speed greater than the rate of extrusion of the
in accordance with the torque effort applied on
plastic material from the extrusion cylinder
said ?rst motor by said screw to maintain the
whereby the extruded material will be elongated
speed of rotation of said ?rst motor relatively
by the conveying means after leaving the ex.
constant and to apply ?said varying ?uid pres
trusion machine.
'
sure on said single acting motor concurrently with
5. An extrusion machine consisting of an ex
the application of the ?uid pressure upon said
trusion cylinder, an extrusion screw therein, ?uid
?rst motor.
?
?
motor means for rotating said screw, a. conveyer
'9. An extrusion machine consisting of, an ex
means for carrying extruded material from the _ trusion cylinder, an extrusion screw rotatable
extrusion machine, ?uid motor means for driv 50 within said cylinder for feeding plastic material
ing said conveyer means, a source of variable
therethrough, a hydraulic motor operably con
pressure ?uid supply? for both of said motor
nected to said extrusion screw for driving same,
means, and means responsive to the discharge,
a variable delivery ?'uid source for supplying ?uid
pressure from either of said motor means for
under pressure to said motor, a hydraulic thrust
dieting a change in operation of the source of 55 bearing for said extrusion screw consisting of a
?uid supply to change the volume of ?uid sup
?single acting hydraulic motor for opposing the
plied therefrom as determined by changes in
axial thrust of said extrusion screw, means hy
load requirements on either of saidmotor means
draulically-connecting said single acting motor to
to maintain the speed of operation thereof sub
stantially constant.
6. An extrusion machine consisting of an ex
trusion cylinder, an extrusion screw, a ?uid motor
for driving said extrusion screw, a ?uid actuated
said variable delivery ?uid source, and means re
60 sponsive to the torque e?ort of said ?rst motor
~for changing the pressure of ?uid applied upon
said motor and upon said single acting motor
concurrently.
,
w
thrust bearing for said extrusion screw having a '
10. An extrusion machine consisting of, an ex
pressure chamber therein whereby the axial 65 trusion cylinder, an extrusion screw rotatable
thrust of said extrusion screw is absorbed by
within said cylinder, a, hydraulic motor operably
the ?uid in said chamber, control means for
connected to said screw for driving the same, a_
regulating the discharge of ?uid from .said hy
variable delivery hydraulic ?uid source, a hy
draulic motor having means to change the resist
draulic thrust bearing for said extrusion screw
ance to ??uid ?ow from said motor in response 70 consisting of a single acting motor, means hy
to the load imposed upon said motor for main
_ draulically connecting said ?uid source with the
taining the speed thereof substantially constant
inlet of said ?rst motor and with said single act
with a varying pressure on the inlet and discharge
ing motor, means hydraulically connecting? the
side of said motor, and means for conducting ?uid '
from'the discharge side 01? said motor to said
discharge side or said ?rst motor with said source, ' '
1; and including resistance valve means therein to
2,411,971 13
-
prevent a free return of hydraulic ?uid from said
?rst motor to said source and establish a ?uid
pressure in the hydraulic connecting'means be
tween said ?rst motor and? said resistance valve
means, and means responsive to the hydraulic
?uid pressure between said ?rst motor and said
resistance valve means for changing the ?uid
pressure delivered by said source to said ?rst mo
tor to maintain the speed thereof relatively con
stant and change the pressure upon saidvsingle 10
acting motor in accordance with the changing
?uid pressure.
'
11. A machine for the extrusion of plastic ma
terial having an extrusion screw for feeding rela
tively constant quantities or plastic material
,
14
within said circuit and interconnected with said
driving means to increase and decrease the pres
sure within said hydraulic bearing in response to
an increase and decrease in the torque from said
screw whereby to maintain said piston and screw
in relatively ?xed position despite torque changes
eiiecting said screw.
>
-
13. A machine for the extrusion of plastic ma
terial having an extrusion screw for feeding rel
atively constant quantities oi.? plastic material
through an extrusion die when the extrusion
screw is rotated, means for maintaining said
screw in a relatively ?xed position comprising a
hydraulic thrust bearing including a chamber
anda piston in said chamber attached to said
screw, 9, ?uid circuit connected to said thrust
through an extrusion die when the extrusion
bearing, means for driving said screw, and means
screw is rotated, means ior maintaining said
in said ?uid circuit and whereby to maintain said
screw in a relatively ?xed position comprising a?
piston and screw in relatively ?xed position de
hydraulic thrust bearing including a chamber
and a piston in said chamber attached to said 20 spite torque changes e?ecting said screw.
14. A machine for the extrusion of plastic ma
screw, a, ?uid circuit connected to said thrust
terial having an extrusion screw for feeding rela
bearing, means for driving said screw, and means
tiveiy constant quantities of plastic material
within said circuit and interconnected with said
through an extrusion die when the extrusion
I driving means to increase and decrease the pres
screw is rotated, means for maintaining said
sure within said hydraulic bearing in response to
an increase and decrease in the torque from said 1 screw in a relatively ?xed? position comprising a
hydraulic thrust bearing including a chamber at
screw whereby to maintain said piston and screw
in relatively ?xed positiondespite torque changes
tached to said screw,? a ?uid circuit connected to
e?ecting said screw.
_
said thrust bearing, means insaid ?uid circuit for
12. A machine for the extrusion of plastic ma� 30 driving said screw, and means within said circuit
interconnected with said driving means to in
terial having an extrusion screw for feeding rei=
crease and decrease the pressure within said hy
atively constant quantities or plastic material
draulic bearing in response to an increase and
through an extrusion die when the extrusion
decrease in the torque from-said screw whereby
screw is rotated, means for maintaining said
screw in a?relativel'y ?xed position comprising a 35 to maintain said piston and screw in relatively
fixed position despite torque changes affecting
hydraulic thrust bearing including a chamber
said screw..
and a piston in said chamber attached to said
HOWARD F.
wu ,1 r.
screw, a fluid means connected to said thrust
PAUL C. POCOCK.
bearing, means for driving said screw, and means
s
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