U.S. patent application number 14/606726 was filed with the patent office on 2015-10-08 for underwater pelletizer.
The applicant listed for this patent is George A. Holmes, Tadeusz Rybka. Invention is credited to George A. Holmes, Tadeusz Rybka.
Application Number | 20150283729 14/606726 |
Document ID | / |
Family ID | 38596163 |
Filed Date | 2015-10-08 |
United States Patent
Application |
20150283729 |
Kind Code |
A1 |
Holmes; George A. ; et
al. |
October 8, 2015 |
Underwater Pelletizer
Abstract
An Underwater pelletizer for cutting extruded plastic into a
flow of liquid is disclosed. The pelletizer includes a cutter hub
(90) carrying at least one cutter blade (96), a cutter shaft (60)
for rotationally driving the cutter hub, and a flexible torque
converter (80) for connecting a motor to the cutter hub. In one
embodiment, the torque converter has a first set of bushings (82)
that is fastened to a face (98) of the cutter hub and a second set
of bushings that is fastened to a face (64) of the cutter shaft.
The disclosed pelletizer has a shaft extension (20) configured to
engage a motor shaft, the shaft extension having an Outer diameter
having formed thereon a splined portion (38) and first (26) and
second (28) sealing surfaces. A disclosed motor adaptor (40) has a
seal surface (44). A water chamber plate (50) may also have a seal
surface (52).
Inventors: |
Holmes; George A.; (West
Chicago, IL) ; Rybka; Tadeusz; (Streamwood,
IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Holmes; George A.
Rybka; Tadeusz |
West Chicago
Streamwood |
IL
IL |
US
US |
|
|
Family ID: |
38596163 |
Appl. No.: |
14/606726 |
Filed: |
January 27, 2015 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
13338029 |
Dec 27, 2011 |
8939744 |
|
|
14606726 |
|
|
|
|
12304675 |
Dec 12, 2008 |
8083509 |
|
|
PCT/US07/71481 |
Jun 18, 2007 |
|
|
|
13338029 |
|
|
|
|
60814659 |
Jun 16, 2006 |
|
|
|
Current U.S.
Class: |
425/67 |
Current CPC
Class: |
B29B 9/065 20130101 |
International
Class: |
B29B 9/06 20060101
B29B009/06 |
Claims
1. An underwater pelletizer for cutting extruded plastic into a
flow of liquid, the pelletizer comprising: a shaft extension (20)
configured to engage a motor shaft, the shaft extension having an
outer diameter having formed thereon a splined portion (38) and
first (26) and second (28) sealing surfaces; a motor adapter (40)
having a seal surface (44); a water chamber plate (50) having a
seal surface (52); a first mechanical seal (48) configured to
engage the first seal surface (26) of the shaft extension and the
seal surface (44) of the motor adapter; a second mechanical seal
(49) configured to engage the second seal surface (28) of the shaft
extension and the seal surface (52) of the water chamber plate; and
a cutter shaft (60) having a splined bore (62) formed therein for
engaging the splined portion (38) of the shaft extension; wherein:
the shaft extension (20), the motor adapter (40), the water chamber
plate (50) and the first and second mechanical seals (48, 49) form
a high pressure chamber (42) when assembled; and the shaft
extension has formed therein a piston chamber (32), an axial bore
(34) in communication with the piston chamber, and a pressure
access hole (36) in communication with the axial bore and the high
pressure chamber; and the pelletizer further includes a hub piston
(70) disposed in the piston chamber (32) and configured to apply
pressure against a cutter hub (90).
2. The underwater pelletizer of claim 1 wherein the motor adapter
(40) has formed therein a pressure port (46) in communication with
the high pressure chamber (42) and the pelletizer further includes
a pressure regulator (250) coupled to the pressure port for
controlling the pressure within the high pressure chamber.
3. The underwater pelletizer of claim 1 wherein the hub piston (70)
is pneumatically controlled by the pressure regulator (250).
4. The underwater pelletizer of claim 1, the pelletizer further
comprising a water chamber housing (100) having formed therein a
water inlet (110) and a water outlet (112), the water chamber
housing being fixedly attached to the water chamber plate (50),
where the water inlet and water outlet are positioned so that
during operation a water vortex is formed within the water chamber
housing that rotates in a same rotational direction as the cutter
hub (90).
5. The underwater pelletizer of claim 4, wherein the water inlet
(110) and the water outlet (112) are positioned substantially
parallel and adjacent to one another.
6. The underwater pelletizer of claim 4, wherein the shaft
extension (20) rotates on a rotational axis and the water inlet and
water outlet are positioned at points offset from the rotational
axis.
7. The underwater pelletizer of claim 4, wherein the pelletizer
further includes: a die (150) for extruding plastic; a die ring
(130) fixedly attached to the die; the water chamber housing
further includes an automatic clamp fitting for engaging the die
ring; and an automatic clamp rotor (140) for clamping the die to
the automatic clamp fitting of the water chamber housing.
8. The underwater pelletizer of claim 4, the water chamber housing
(100) having formed therein a drain outlet (114), the pelletizer
further comprising a valve (240) coupled to the drain outlet (114)
and has a hose fitting (242) for receiving a hose for draining the
water chamber housing (100).
Description
FIELD OF THE INVENTION
[0001] This invention pertains to the field of underwater
pelletizers, which are adapted to be mounted to the end of an
extruder for cutting streams of plastic extruded through a die into
pellets, which are carried away by water flow in a water chamber
where the cutting takes place.
BACKGROUND OF THE INVENTION
[0002] Extruders for extruding plastic material from a molten
stream of plastic material have been known and used for some time.
One particular use of such an extruder is in connection with a
pelletizer assembly, which is mounted to the end of the extruder.
In such a combination of an extruder and a pelletizer, a die having
a plurality of holes therein is mounted at the end of the extruder
and at the entrance to the pelletizer assembly and forms part of
both. The pelletizer then includes a rotating cutter assembly
having cutting blades positioned adjacent the die face from which
streams of molten plastic material flow. The rotating cutter
assembly cuts the streams of plastic material into pellets of
various sizes depending upon the extrusion flow rate through the
holes in the die and the speed of rotation of the cutter
assembly.
[0003] Also, the flow of water through the chamber serves to carry
the pellets away from the chamber.
[0004] In such a combined extruder and pelletizer assembly it is
desirable to provide means for facilitating a smooth flow of the
plastic material from the extruder to the die holes in the die.
Also it is desirable to provide means for gaining easy access to
the chamber for servicing the pelletizer, such as to replace worn
cutting blades of the cutter assembly, to generally observe the
formation of pellets by the rotating cutter assembly, and to clean
the die.
[0005] It is also desirable to provide a long useful life for the
cutting blades of the cutter assembly and die. That is to say, it
is desirable to provide cutting blades that will last a long time.
In addition, it is desirable to provide some means for
automatically readjusting the position of the cutter assembly
adjacent the die face as the space between the cutter assembly and
the die face increases due to wear of the cutting blades. In this
respect, it is desirable to keep the cutting blades juxtaposed to
the die face to ensure clean cutting of the streams of plastic
material into pellets.
[0006] U.S. Pat. No. 4,529,370 illustrates one example of a
conventional underwater pelletizer.
[0007] Another example of a conventional underwater pelletizer is
shown in U.S. Pat. No. 5,059,103. Some conventional components for
pelletizers are shown in U.S. Pat. Nos. 4,621,996; 5,403,176;
5,624,688; and 6,332,765.
BRIEF SUMMARY OF THE INVENTION
[0008] An embodiment of an underwater pelletizer includes a
flexible torque converter disc that engages a cutter hub having
cutting blades and a cutter drive hub that is driven by a motor.
The flexible torque converter disc accommodates misalignment
between a motor shaft and a die face and maintains the cutting
blades in contact with a die face during rotation. In a further
refinement, mechanical seals are provided for a shaft extension to
pass through a motor adaptor and a water chamber plate and provide
for a high-pressure chamber. An access hole and a bore through the
shaft extension permit a hub piston to be controlled by varying the
pressure in the high pressure chamber in order to control the
pressure of the cutting hub against the die face. In still another
refinement, the water chamber has a water inlet and outlet arranged
so that water pumped into the water chamber forms a vortex that
rotates in the same direction as the rotation of the cutter hub. In
a further refinement of this embodiment, the water chamber is
fixedly attached to the motor adaptor and removably coupled to the
die.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] An exemplary embodiment is described below with respect to
the following drawings, wherein:
[0010] FIG. 1 is an exploded view showing individual components of
an embodiment of a pelletizer with an automatic water chamber
clamp;
[0011] FIG. 2 is a front view of the cutting hub of FIG. 1;
[0012] FIG. 3 is a side view of the cutting hub of FIG. 1;
[0013] FIG. 4 is a top view of the cutting blade of FIGS. 1-3;
[0014] FIG. 5 is an isometric view of the cutting blade of FIGS.
1-4;
[0015] FIG. 6 is an assembled side view illustrating the water
chamber housing of FIG. 1 and associated water circulation
equipment;
[0016] FIG. 7 is an assembled cross-sectional view of the
underwater pelletizer of FIGS. 1 and 6 that also illustrates
automated clamping and pressure actuation components;
[0017] FIG. 8 is an exploded side view of the components of a
cutter shaft assembly that includes a motor shaft extension, cutter
shaft, hub piston, flexible disc coupling and cutter hub;
[0018] FIG. 9 is a frontal view of one embodiment of a flexible
disc having four bushings and
[0019] FIG. 10 is a side view of the same embodiment;
[0020] FIGS. 11 and 12 are side and frontal views, respectively, of
an embodiment of a cutter shaft;
[0021] FIGS. 13 and 14 are side and frontal views, respectively, of
an embodiment of a shaft extension;
[0022] FIGS. 15, 16 and 17 are rear, side and frontal views,
respectively, of an eight bladed embodiment of a cutter hub;
[0023] FIG. 18 is a side view of an embodiment of a piston for a
diverter valve with grooves formed on a periphery of the
piston.
DETAILED DESCRIPTION OF THE INVENTION
[0024] It is desirable to maintain the cutting blades of an
underwater pelletizer in contact with a die face of an extrusion
die in order to produce pellets of relatively uniform size and
shape, as well as to avoid jamming the cutting blades with extruded
plastic.
[0025] One conventional cutting blade configuration present in
devices produced by Gala Industries, Inc., includes a self-aligning
cutting blade assembly that attaches to a motor shaft through a
spherical coupling. The spherical coupling consists of a cut-away
ball joint that is threaded for connection to a motor shaft. A pair
of ball bearings and associated traces are used to implement a
floating connection between the spherical coupling and the rest of
the cutting blade assembly.
[0026] As the shaft rotates about a rotational axis, the spherical
coupling permits the cutting blade assembly to float, e.g. move
with respect to the rotational axis, in order to compensate for
misalignment between the shaft and the die. The movement of the
spherical coupling maintains the cutting blades in contact with the
die face. However, the spherical coupling is used to transmit axial
force for forcing the cutting blade assembly against the die face
and radial force for rotating the cutting blade assembly using the
motor shaft. Consequently, a large amount of force is focused on
the ball bearing traces and they are prone to rapid wearing.
[0027] It is also desirable to provide for rapid cleaning of the
cutting blades, die and water chamber, which must be cleared of
excess extruded plastic in order to operate properly. Conventional
underwater pelletizers provide for the plastic to be extruded
through holes in the die face into a water chamber, where the
plastic is cut by the cutting assembly. During start-up procedure
the water chamber is flooded with plastic and it has to be manually
removed by the operator. The water chamber is typically fixedly
attached to the die and a motor adaptor with a water seal is
removably coupled to the other end of the water chamber.
[0028] The water seals provided in conventional underwater
pelletizers are typically oil seals, which tend to break down if
subjected to significant levels of water pressure. Breakdown of the
seals leads to water entering the motor assembly, which can damage
the motor and requires replacement of the seals.
[0029] Conventional water chambers have a water intake on one side
of the chamber, e.g. the bottom, for inflow of water and an outlet
on another side, e.g. the top, for outflow of water and pelletized
material. The resulting flow of material is in one direction
through the chamber. The cutting blade assembly rotates within the
water chamber in approximately the same plain as the vector of the
water flow through the chamber. Consequently, the blades of the
cutting blade assembly rotate substantially with the water flow
through half their rotation and against the water flow through the
other half of their rotation. As a result, a significant amount of
power is required to drive the cutting blade assembly against the
flow of water in the water chamber.
[0030] Conventional blades used in conventional cutting blade
assemblies typically have two sharpened cutting edges that engage
the die face for cutting plastic as it is extruded. These blades
are sharpened on opposing edges of a body of the blade, where the
cutting edge is formed on opposing planar sides of the body so that
the blade can be removed and reversed when one cutting edge has
worn out. The conventional blades typically have two bolt holes for
bolting the blade into the cutting blade assembly so that the blade
does not rotate out of position under load when the cutting blade
assembly is engaged and rotated against the die face. The
conventional blades wear out after the two cutting edges are used
up.
[0031] FIG. 1 is an exploded view of an exemplary embodiment of an
improved underwater pelletizer. A motor 10 has a shaft 12 that
engages shaft extension 20. The shaft extension 20 passes through a
motor adaptor 40 and water chamber plate 50 to engage cutter shaft
60. A dual mechanical shaft seal assembly 48 is used to provide a
seal between the shaft extension 20 and motor adaptor 40 at both a
motor side and a water chamber plate side. Another mechanical seal
engages water chamber plate 50 and provides a seal for shaft
extension 20 between motor adaptor 40 and water chamber plate 50.
Shaft extension 20 also engages hub piston 70, which engages
pressure plate 92 of cutter hub 90.
[0032] Water chamber housing 100 has a first open end 102 that is
coupled to water chamber plate 50 such that cutter shaft 60 and
cutter hub 90 are disposed within water chamber bore 104. A second
open end 106 of water chamber housing 100 is adapted to engage die
ring 130 and driven rotor 140 removably couples thru the set of
eccentrically guided pins with radial bearings water chamber
housing 100 to die 150. Die 150 is fixedly connected to die ring
130 on one side and to die clamp adaptor 160 on the other side,
which engages clamp 180 for clamping die 150 to diverter valve 190.
Flow distributing insert 170 facilitates annular flow of plastic
from diverter valve 190 to die 150, where the plastic is extruded
through holes in die face 152.
[0033] The shaft extension 20 has a first bore 22 for engaging
shaft 12 of motor 10. A seal surface 26 is provided for seating a
first mechanical shaft seal 48 against seal surface 44 of motor
adaptor 40. Another seal surface 28 is provided for seating second
mechanical shaft seal 49 against seal surface 52 of water chamber
plate 50. When shaft extension 20 is assembled with motor adaptor
30 and water chamber plate 50 with mechanical shaft seals 48 and
49, a high-pressure chamber 42 is formed with motor adaptor 40 and
water chamber plate 50, where the pressure in the high pressure
chamber 42 may be controlled via pressure regulator 250 illustrated
in FIG. 7.
[0034] Shaft extension 20 also includes piston chamber 32 for
receiving hub piston 70. Piston chamber 32 is in communication with
pressure access hole 36 via axial bore 34. When assembled, pressure
access hole 36 is in communication with high-pressure chamber 42 of
motor adaptor 40 and hub piston 70 is seated in piston chamber 32.
Consequently, the axial force applied to pressure plate 92 of
cutter hub 90 by hub piston 70 may be controlled by varying the
pressure in high-pressure chamber 42 via pressure regulator 250
attached to pressure port 46, as illustrated in FIG. 7. Thus, the
axial pressure of cutter hub 90 against die face 152 is externally
controllable during operation of the pelletizer.
[0035] Motor shaft extension 20 has a splined outer surface region
38 that, when assembled, engages splined bore 62 of cutter shaft
60. Cutter shaft 60 has a flexible disc engagement face 64 that is
formed to engage bushings 82 of flexible torque transmitting disc
80. Cutter hub 90 also has a disc engagement face 98 that is formed
to engage bushings 82 of flexible torque transmitting disc 80. When
assembled, rotary force generated by shaft 12 of motor 10 is
transmitted through shaft extension 20 to cutter shaft 60 and from
cutter shaft 60 through flexible torque transmitting disc 80 to
cutter hub 90 in order to rotate the cutter blades 96 against die
face 152 of die 150. Flexible torque transmitting disc 80 is a
standard torque-transmitting device that is a generally available
power transmission product frequently used in other power
transmission applications. In the present embodiment, disc 80 is
constructed of laminated sheets of stainless steel that permits
approximately 5.degree. of movement. The stainless steel prevents
disc 80 from corroding due to contact with water in water chamber
housing 100. The flexibility of disc 80 permits it to accommodate
both angular and parallel misalignment between motor shaft 12 and
die 150. Disc 80 transmits only rotary force from cutter shaft 60
to cutter hub 90 and transmits no axial force necessary to keep the
blades 96 attached to the cutter hub 90 against die face 152.
[0036] Note that the cutter hub 90, cutter shaft 60, blades 96,
flexible disc 80 and die 150 arrangement operates to maintain
substantially consistent pressure of the blades against the die
face 152. This results in blades 96 self-sharpening as they rotate
against the die face 152. By avoiding uneven wear of the die face
152, the present arrangement can extend the operational life of the
die 150.
[0037] As shown in FIG. 1, water chamber housing 100 has a water
inlet opening 110, a water outlet opening 112, and a drain outlet
114. The water inlet 110 and water outlet 112 are formed in the
water chamber housing such that they are substantially parallel and
adjacent to one another. When the pelletizer is assembled, the
water inlet 110 and outlet 112 are arranged with respect to the
rotation of cutter hub 90 so that a water vortex is formed within
water chamber housing 100 that rotates in the same direction as
cutter hub 90. The resulting arrangement substantially reduces the
amount of power required to rotate cutter hub 90 while cutting
extruded plastic. It also results in improved pellet removal and
reduces jamming.
[0038] In the pelletizer of FIG. 1, water chamber housing 100 is
fixedly attached, e.g. bolted, to water chamber plate 50, which is
connected to motor adaptor 40. In this embodiment, water chamber
housing 100 is formed with an automatic clamp fitting for engaging
die ring 130 via an automatic clamp rotor 140, which is discussed
in further detail below with regard to FIG. 7. When the pelletizer
is assembled, water chamber housing 100 is fixedly attached to
motor 10 and removably coupled to the die ring 130 and the die 150
via a clamping mechanism.
[0039] If an automated clamp mechanism is used in conjunction with
a melt diverting valve and automatic water bypass system, then the
start-up and shut-down process for the pelletizer can be fully
automated. This arrangement substantially improves system
efficiency and operator safety over manual procedure.
[0040] The embodiment of FIG. 1 includes a die clamp adaptor 160
for fixed attachment to die 150. The die 150 is then removably
coupled to diverter valve 190 via quick clamp 180. This arrangement
permits that both the front and back of die 150 are rapidly
accessible for maintenance and cleaning.
[0041] FIGS. 2 and 3 show an exemplary embodiment of cutter hub 90
of FIG. 1. FIG. 2 is a front view of the cutter hub from the
perspective of the die face 152 that faces hub lid 94. FIG. 3 is a
side view of the cutter hub. Cutter hub 90 includes multiple cutter
blades 96A-D arranged along a periphery of the cutter hub 90 and
secured within slots formed in housing 210, e.g. slot 214C shown in
FIG. 3. The slots are formed in housing 210 of cutter hub, and are
wide enough to receive and hold securely a center portion 220
(shown in FIGS. 4 and 5) of each cutting blade 96. FIG. 3 shows
slot 214C for mounting one of the blades 96C of FIG. 2. A drilled
and tapped bore 212C is formed into housing 210 of hub 90 for
insertion, in this example, of a conical tip set screw 216C for
aligning and securing blade 96C within the housing 210 through
screw hole 224 in the blade.
[0042] FIGS. 4 and 5 show an exemplary embodiment of cutting blades
96A-D. Each cutting blade 96 is substantially symmetrical along two
perpendicular axes A and B. A central portion 220 of cutting blade
96 is positioned along axis B and has a substantially rectangular
cross-section for holding the blade securely within slot 214 in the
cutting hub housing 210. Each cutting blade has up to four cutting
edges 222A-D formed into it, where the cutting edges are formed
proximally from the central portion and perpendicular to axis A.
The cutting edges 222A-D are formed on two opposing surfaces X and
Y of blade 96. Diametrically opposed cutting edges are formed on
the same surface. For example, edges 222A and 222C are formed on
planar surface Y and edges 222B and 222D are formed on planar
surface X. The resulting cutting blade 96 may be removed from
cutter hub 90 and rotated so that all four edges 222A-D may be used
for cutting before blade 96 is worn out. Removing and rotating
blade 96 is accomplished by backing out set screw 216, rotating
and/or reversing blade 96, and resetting set screw 216.
[0043] In a preferred embodiment, a single securing hole 224 is
formed at the intersection of axes A and B of blade 96. The
securing hole 224 is adapted to engage set screw 216 threaded
through bore 212 in the cutter hub housing 210 that holds the
cutting blade securely in place within cutter hub 90. This
arrangement results in the cutting blade being self-aligning within
cutter hub 90. The conical tip of set screw 216, along with the
alignment of screw hole 224 and bore hole 212 combine to align
blade 96 within the housing 210.
[0044] FIG. 6 is an assembled side view illustrating the water
chamber housing 100 of FIG. 1 fixedly coupled to motor adaptor 40
and motor 10 along with associated water circulation ports. Flow
sight 230, which allows water and pelletized material to be
observed leaving water chamber housing 100, is coupled to water
outlet 112 via cam and groove coupling 236 and on top is coupled to
hose fitting 232 via cam and groove coupling 234, where hose
fitting receives a water and pellet hose typically for transporting
the resulting pelletized material to a pellet dryer. Water inlet
110 is coupled to hose fitting 238 via cam and groove coupling 237,
where hose fitting 238 receives a water supply line. Pneumatic
valve 240 is coupled to drain outlet 114 and has a hose fitting 242
for receiving a hose for draining water chamber housing 100.
[0045] FIG. 7 is an assembled cross-sectional view of the
underwater pelletizer of FIGS. 1 and 6 that also illustrates
automated clamping and pressure actuation components. Motor 10 is
secured to motor adaptor 40, which is secured to water chamber
plate 50. Shaft extension 20 is coupled to motor shaft 12 and
extends through high pressure chamber 42 formed within motor
adaptor 40 along with shaft extension 20 and water chamber plate
50. Mechanical shaft seal 48 forms a high pressure seal between
shaft extension 20 and motor adaptor 40. Mechanical shaft seal 49
forms a high pressure seal between shaft extension 20 and water
chamber plate 50. In one example, mechanical shaft seals 48 and 49
are ceramic and graphite disc seals actuated by a stainless steel
spring, which are widely used in other equipment applications.
[0046] A pressure regulator 250 (manual or electronic) is connected
to supply port 46 and regulates the pressure in high-pressure
chamber 42. The pressure in high-pressure chamber 42, in turn,
affects the amount of force applied by hub piston 70 to pressure
plate 92 of cutting hub 90 via pressure access hole 36 and axial
bore 34. By controlling the pressure in high pressure air chamber
42, the amount of axial force applied by hub piston 70 to cutting
hub 90 is controlled during pelletizer operation or blade lapping
sequence.
[0047] Shaft extension 20 passes through water chamber plate 50
into water chamber 101 formed by water chamber housing 100. Cutter
shaft 60 is fitted onto shaft extension 20 and is coupled to
cutting hub 90 through flexible disc 80. The blades 96 of cutting
hub 90 are pressed against the face of extrusion die 150 by hub
piston 70. When motor shaft 12 rotates, shaft extension 20 also
rotates causing cutter shaft 60, flexible disc 80 and cutting hub
90 to rotate in order to cut plastic extruded through holes in die
150.
[0048] In the embodiment of FIG. 7, clamp 180 is a hinged quick
clamp for engaging die clamp adaptor 160, which is fastened to die
150, and a clamp flange 192 of diverter valve 190. An actuator 300
has a drive shaft 302 for rotationally driving driven gear 304.
Driven gear 304 engages rotor 140 fastened to water chamber housing
100 in order to open or close water chamber 101. By automatically
controlling actuator 300, pressure regulator 250, melt diverter
valve 190 and a water bypass system start-up and shut-down of the
pelletizer can be fully automated.
[0049] The water bypass system noted above diverts water from a
hose connected to hose attachment 238 for water inlet 110 shown in
FIG. 6 to a hose connected to hose attachment 232 connected to
water outlet 112. This arrangement permits water chamber 100 to be
automatically drained during a shut-down operation, but maintain
the inertial flow of water in a water circulation system that
attaches to hose attachments 232 and 238. This allows the time
required to service an interruption of operation to be reduced.
[0050] FIG. 8 is an exploded side view of the components of a
cutter shaft assembly that includes shaft extension 20, cutter
shaft 60, hub piston 70, flexible disc 80 and cutter hub 90. This
expanded view illustrates o-rings 72 and 74 on hub piston 70, which
form a seal between hub piston 70 and piston chamber 32 of shaft
extension 20. As the pressure within high-pressure chamber 42 of
FIG. 7 is varied, hub piston 70 moves within piston chamber 32. A
retainer ring 76 seats into an end of shaft extension 20 and
prevents hub piston 70 from being ejected from piston chamber
32.
[0051] Also shown in FIG. 8 are fasteners 84A-C for securing
flexible hub 80 to cutter shaft 60 and cutting hub 90. In the
embodiment shown, a pair of fasteners 84A and 84C secure disc 80 to
drive shaft 60. Another pair of fasteners, fastener 84B and where
the other fastener is obscured from view by fastener 84B, secures
disc 80 to cutting hub 90. The fasteners are inserted through
bushings on flexible disc 80 in an alternating fashion such that
each pair of adjacent bushings on flexible disc 80 is secured to a
different one of cutter shaft 60 and cutting hub 90. This
arrangement permits the disc to flex in order to accommodate
misalignment between cutter shaft 60 and cutting hub 90.
[0052] FIG. 8 also shows a retainer ring 66 that secures pressure
plate 92 to cutter hub 90.
[0053] FIG. 9 is a frontal view of one embodiment of flexible disc
80 having four bushings 82A-D and FIG. 10 is a side view of the
same embodiment. As an example of securing flexible disc 80 in an
alternating fashion, bushings 82A and 82C are secured to cutter
shaft 60 and bushings 82B and 82D are coupled to cutter hub 90.
Other arrangements are possible, as are other embodiments where
there are a larger number of bushings utilized.
[0054] FIGS. 11 and 12 are side and frontal views, respectively, of
an embodiment of cutter shaft 60. Note that disc engagement face 64
that is formed to engage bushings 82 of flexible torque
transmitting disc 80 includes, in one exemplary embodiment,
threaded bores 362A and 362B for receiving fasteners 84A and 84C of
FIG. 8 for securing bushings 82A and 82C of flexible disc 80 to
cutter shaft 60. Also note recesses 364A and 364B, which
accommodate fastener 84B and another fastener that is obscured in
FIG. 8 for securing bushings 82B and 82D to cutting hub 90. Note
that recesses 364A and 364B are preferably sized larger than the
heads of fastener 84B to allow for flexion in disc 80. Further note
in FIG. 12 the splined surface 366 of splined bore 62 for receiving
splined outer surface region 38 of shaft extension 20 shown in FIG.
14.
[0055] FIGS. 13 and 14 are side and frontal views, respectively, of
an embodiment of shaft extension 20. As noted above, piston chamber
32 is in communication with pressure access hole 36 via axial bore
34 so that, when assembled, pressure access hole 36 is in
communication with high-pressure chamber 42 of motor adaptor 40
shown in FIG. 7. Shaft extension 20 has a splined outer surface
region 38 that, when assembled, engages splined bore 62 of cutter
shaft 60.
[0056] Piston chamber 32 is in communication with pressure access
hole 36 via axial bore 34, as further illustrated in FIG. 7. When
assembled, as illustrated in FIG. 7, pressure access hole 36 is in
communication with high-pressure chamber 42 of motor adaptor 40 and
hub piston 70 is seated in piston chamber 32. Consequently, the
axial force applied to pressure plate 92 of cutter hub 90 by hub
piston 70 may be controlled by varying the pressure in
high-pressure chamber 42 via pressure supply port 46. Thus, the
axial pressure of cutter hub 90 against die face 152 is dynamically
controllable during operation of the pelletizer or blade lapping
sequence.
[0057] As shown in FIG. 14, shaft extension 20 has a splined outer
surface region 38 that, when assembled, engages splined bore 62 of
cutter shaft 60, shown in FIG. 12. The splines of splined bore 62
may be formed by gear cutting or honing the interior surface of
bore 62, which results in a robust engagement of the shaft
extension 20 to cutter shaft 60. Seal surface 26, shown in FIGS. 13
and 14, is provided for seating a mechanical shaft seal 48 against
seal surface 44 of motor adaptor 40, shown in FIG. 1. Another seal
surface 28, shown in FIG. 13, is provided for engaging second
mechanical shaft seal against seal surface 52 of water chamber
plate 50, shown in FIG. 1.
[0058] FIGS. 15, 16 and 17 are rear, side and frontal views,
respectively, of an eight bladed embodiment of a cutter hub 90B.
FIG. 14 shows a disc engagement face 398 that is formed to engage
bushings 82 of flexible torque transmitting disc 80. In this
embodiment, disc engagement face includes threaded bores 392A and
392B for receiving fastener 84B and another fastener that is
obscured in FIG. 8 for securing bushings 82B and 82D to cutting hub
90. Also note recesses 394A and 394B, which accommodate fasteners
84A and 84C of FIG. 8 for securing bushings 82A and 82C of flexible
disc 80 to cutter shaft 60. Note that recesses 394A and 394B are
preferably sized larger than the heads of fasteners 84A and 84C to
allow for flexion in disc 80.
[0059] Further note slot 414A formed in the body of hub 390 for
receiving a cutting blade, such as those discussed above. A
threaded bore 412A is formed at an angle and intersects slot 414A
so that a set screw can be used to secure the cutting blade in
place within slot 414A. Note that other configurations for cutter
hub are possible, such as a six bladed embodiment.
[0060] In one embodiment, the diverter valve 190 shown in FIGS. 1
and 6 has a piston 194 with peripheral grooves formed thereon, as
shown in FIG. 18. In this embodiment, the grooves are approximately
1/8 of an inch wide and deep. Because the diverter valve piston 194
is typically subject to tight tolerances, e.g. thousandths of an
inch, with the diverter valve housing 190, the piston 194 is
vulnerable to jamming due to contaminant particles, such as metal
filings or wood splinters, that tend to jam conventional pistons.
In this embodiment, the peripheral grooves trap the contaminant
particles to prevent the particles from jamming the piston 194.
Also, molten plastic within the diverter valve 190 tends to
solidify within the grooves and helps form a seal between the
piston 194 and the diverter valve 190.
[0061] All references, including publications, patent applications,
and patents, cited herein are hereby incorporated by reference to
the same extent as if each reference were individually and
specifically indicated to be incorporated by reference and were set
forth in its entirety herein.
[0062] The use of the terms "a" and "an" and "the" and similar
referents in the context of describing the invention (especially in
the context of the following claims) are to be construed to cover
both the singular and the plural, unless otherwise indicated herein
or clearly contradicted by context. Recitation of ranges of values
herein are merely intended to serve as a shorthand method of
referring individually to each separate value falling within the
range, unless otherwise indicated herein, and each separate value
is incorporated into the specification as if it were individually
recited herein. All methods described herein can be performed in
any suitable order unless otherwise indicated herein or otherwise
clearly contradicted by context. The use of any and all examples,
or exemplary language (e.g., "such as") provided herein, is
intended merely to better illuminate the invention and does not
pose a limitation on the scope of the invention unless otherwise
claimed. No language in the specification should be construed as
indicating any non-claimed element as essential to the practice of
the invention.
[0063] Preferred embodiments of this invention are described
herein, including the best mode known to the inventors for carrying
out the invention. It should be understood that the illustrated
embodiments are exemplary only, and should not be taken as limiting
the scope of the invention
* * * * *