U.S. patent application number 17/242976 was filed with the patent office on 2021-08-12 for plasticating apparatus screw having grooves of varying angles and depths.
This patent application is currently assigned to Davis-Standard, LLC. The applicant listed for this patent is Davis-Standard, LLC. Invention is credited to John P. Christiano.
Application Number | 20210245398 17/242976 |
Document ID | / |
Family ID | 1000005550518 |
Filed Date | 2021-08-12 |
United States Patent
Application |
20210245398 |
Kind Code |
A1 |
Christiano; John P. |
August 12, 2021 |
PLASTICATING APPARATUS SCREW HAVING GROOVES OF VARYING ANGLES AND
DEPTHS
Abstract
A screw for a plasticating apparatus has one or more helical
flights. A portion of the screw has a plurality of advancing
grooves arranged in a noncontinuous helix cut in the screw. The
advancing grooves are dimensioned to receive material therein as
the material is conveyed through the barrel. The screw has a
plurality of noncontinuous cross-cut grooves traversing one or more
of the advancing grooves. The cross-cut grooves have a second helix
angle greater than the first helix angle and less than ninety
degrees; and/or one or more of the cross-cut grooves have a third
helix angle of about ninety degrees.
Inventors: |
Christiano; John P.; (Old
Lyme, CT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Davis-Standard, LLC |
Pawcatuck |
CT |
US |
|
|
Assignee: |
Davis-Standard, LLC
Pawcatuck
CT
|
Family ID: |
1000005550518 |
Appl. No.: |
17/242976 |
Filed: |
April 28, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16697491 |
Nov 27, 2019 |
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17242976 |
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15091802 |
Apr 6, 2016 |
10532490 |
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16697491 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B29C 48/535 20190201;
B29C 48/53 20190201; B29C 48/615 20190201; B29C 48/605 20190201;
B29B 7/429 20130101; B29C 48/56 20190201; B29C 48/03 20190201; B29C
48/397 20190201; B29C 48/832 20190201; B29C 48/64 20190201; B29C
48/60 20190201; B29C 48/67 20190201; B29C 48/655 20190201 |
International
Class: |
B29B 7/42 20060101
B29B007/42; B29C 48/56 20190101 B29C048/56; B29C 48/53 20190101
B29C048/53; B29C 48/615 20190101 B29C048/615; B29C 48/535 20190101
B29C048/535; B29C 48/60 20190101 B29C048/60; B29C 48/605 20190101
B29C048/605 |
Claims
1. A screw for a plasticating apparatus, the screw comprising: a
longitudinal axis, the screw being rotatably supportable in a
barrel for rotation about the longitudinal axis, the screw having a
core and at least one helical flight extending along a length of
the screw, the helical flight having a radially outermost flight
surface, the helical flight extending in a first threaded direction
and defining a first helical path of a first helix angle measured
relative to a reference line perpendicular to the longitudinal
axis, the first helix angle being less than ninety degrees; the
helical flight defining a helical channel; and a longitudinal
portion of the screw having a plurality of advancing grooves with
each advancing groove having at least one closed-end, the advancing
grooves being arranged in a noncontinuous helix cut in the screw
core in the helical channel of the screw, each of the plurality of
advancing grooves forming a second helical path in the helical
channel and being arranged entirely between adjacent helical
flights and extending substantially parallel to the helical
flights, and the plurality of advancing grooves being dimensioned
to receive material therein as the material is conveyed forward
through the helical channel; the longitudinal portion further
having at least one undercut surface located radially inwardly from
the radially outermost flight surface, wherein the undercut surface
has a depth that varies at least one of: in a longitudinal
direction parallel to the plurality of advancing grooves; and in a
direction traverse to the longitudinal direction.
2. The screw of claim 1, wherein the at least one undercut surface
includes one or more first undercut surfaces adjacent to the
helical flight.
3. The screw of claim 2, wherein: the at least one undercut surface
further includes a second undercut surface located on an opposite
side of a first advancing groove, among the advancing grooves, from
one of the first undercut surfaces, and the one of the first
undercut surfaces has a first depth.
4. The screw of claim 3, wherein: the second undercut surface has a
second depth that is less than the first depth, and the second
undercut surface is located radially inwardly from the radially
outermost flight surface.
5. The screw of claim 4, wherein the at least one undercut surface
further includes a third undercut surface located on an opposite
side of a second advancing groove, among the advancing grooves,
from the second undercut surface.
6. The screw of claim 5, wherein: the third undercut surface has a
third depth that is greater than the second depth, and the third
undercut surface is located radially inwardly from the radially
outermost flight surface.
7. The screw of claim 6, wherein the third undercut surface is
located on an opposite side of a third advancing groove, among the
advancing grooves, from another one of the first undercut
surfaces.
8. The screw of claim 1, wherein: the at least one undercut surface
includes a first portion having a first depth, and the first depth
is substantially constant along the longitudinal direction.
9. The screw of claim 8, wherein: the at least one undercut surface
further includes a second portion adjacent to the first portion,
the second portion has an increasing depth taper along the
longitudinal direction, and a portion of the increasing depth taper
has a second depth that is greater than the first depth.
10. The screw of claim 9, wherein: the at least one undercut
surface further includes a third portion adjacent to the second
portion, the third portion has a third depth, and the third depth
is substantially constant along the longitudinal direction and is
greater than the second depth.
11. The screw of claim 10, wherein: the at least one undercut
surface further includes a fourth portion adjacent to the third
portion, the fourth portion has a decreasing depth taper along the
longitudinal direction, and a portion of the decreasing depth taper
has a fourth depth that is less than the third depth.
12. The screw of claim 11, wherein: the at least one undercut
surface further includes a fifth portion adjacent to the fourth
portion, and the fifth portion has a fifth depth that is less than
the fourth depth.
13. A screw for a plasticating apparatus, the screw comprising: a
longitudinal axis, the screw being rotatably supportable in a
barrel for rotation about the longitudinal axis, the screw having a
core and at least one helical flight extending along a length of
the screw, the helical flight having a radially outermost flight
surface, the helical flight extending in a first threaded direction
and defining a first helical path of a first helix angle measured
relative to a reference line perpendicular to the longitudinal
axis, the first helix angle being less than ninety degrees; the
helical flight defining a helical channel; and a longitudinal
portion of the screw having a plurality of advancing grooves with
each advancing groove having at least one closed-end, the advancing
grooves being arranged in a noncontinuous helix cut in the screw
core in the helical channel of the screw, each of the plurality of
advancing grooves forming a second helical path in the helical
channel and being arranged entirely between adjacent helical
flights and extending substantially parallel to the helical
flights, and the plurality of advancing grooves being dimensioned
to receive material therein as the material is conveyed forward
through the helical channel; the longitudinal portion further
having at least one undercut surface located radially inwardly from
the radially outermost flight surface, wherein the undercut surface
has a depth that varies.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] The instant application is a divisional application of U.S.
Non-Provisional patent application Ser. No. 16/697,491, filed Nov.
27, 2019, which is a divisional application of U.S. Non-Provisional
patent application Ser. No. 15/091,802, filed Apr. 6, 2016, now
U.S. Pat. No. 10,532,490 and entitled "Plasticating Apparatus Screw
Having Grooves of Varying Angles and Depths," the entirety of which
is incorporated herein by reference.
FIELD
[0002] This invention relates to a plasticating apparatus screw
rotatable within a barrel to extrude molten resinous material. More
particularly, this invention relates to a longitudinal portion of
the screw designed to recirculate material for thorough mixing and
melting via grooves of various angles and having various depths and
depth tapers.
BACKGROUND
[0003] A plasticating apparatus typically receives polymer or
thermoplastic resin pellets, granules or powders, from an inlet
port, then heats and works the resin to convert it into a melted or
molten state. The melt or molten material is delivered under
pressure through a restricted outlet or discharge port to make the
finished article. It is desirable that the molten material leaving
the apparatus be completely melted and homogeneously mixed,
resulting in uniform temperature, viscosity, color and
composition.
[0004] A typical plasticating apparatus includes an elongated
cylindrical barrel, which is usually heated at various locations
along its length. An axially supported and rotating screw extends
longitudinally through the barrel. The screw is responsible for
forwarding, melting, pressurizing and homogenizing the material as
it passes from the inlet port to the outlet port. The screw has a
core with a helical flight thereon and the flight cooperates with
the cylindrical inner surface of the barrel to define a helical
channel for forward passage of the resin to the outlet port.
[0005] The typical plasticating screw has a plurality of sections
along its longitudinal axis with each section being designed for a
particular function. Ordinarily, there is a feed section, a
transition section, a metering section and a mixing section in
series.
[0006] As disclosed in U.S. Pat. No. 6,498,399 and illustrated in
FIG. 1 a plasticating screw 100 has a main channel defined by a
helical flight 113 disposed within and cooperating with an
inner-wall of a heated barrel (not shown). As illustrated in FIG.
1, the prior art screw 100 has a longitudinal portion with a
plurality of staggered rows of noncontinuous advancing grooves 130
arranged in the main channel thereof. The axis of each row of
advancing grooves 130 is substantially parallel to the helical axis
of the adjacent helical flight 113 of the longitudinal portion to
promote flow in the direction indicated by the arrow 140. A
noncontinuous helical channel is formed therein traversing in a
reverse direction, compared with the direction of the helical
flight 113, the channel having a plurality of retracting grooves
137. While the objective of the retracting grooves 137 is to
promote mixing of the polymer or thermoplastic resin pellets in the
main channel, in some instances mixing is insufficient.
[0007] Based on the foregoing, it is the general object of this
invention to provide a screw configured for improved mixing of the
polymer or thermoplastic resin pellets.
SUMMARY
[0008] The present invention resides in one aspect in a screw for a
plasticating apparatus. The plasticating apparatus includes a
barrel that has an axial length extending between an inlet port and
an outlet port. The barrel has an inner wall. The screw has a
longitudinal axis and is rotatably supported in the barrel for
rotation about the longitudinal axis. The screw has a core and one
or more helical flights extending along a length of the screw. The
helical flight extends in a first threaded direction and defines a
first helix angle relative to a reference line perpendicular to the
longitudinal axis and defines a first helical path oriented at the
first helix angle which is less than ninety degrees. The helical
flight defines a helical channel. The screw may include a feed
section cooperating with the inlet port, an intermediate melt
section, and/or a metering section cooperating with said outlet
port. A longitudinal portion of the screw (e.g., in the feed
section, the intermediate melt section, and/or the metering
section) has a plurality of advancing grooves formed therein. Each
of the advancing grooves has one or both ends closed. The advancing
grooves are arranged in a noncontinuous helix cut in the screw core
in the helical channel of the screw. The plurality of advancing
grooves are dimensioned to receive material therein as the material
is conveyed through the helical channel, to the outlet port. The
longitudinal portion further has a plurality of noncontinuous
cross-cut grooves traversing one or more of the advancing grooves.
One or more of the cross-cut grooves has a second helix angle
(measured relative to a reference line perpendicular to the
longitudinal axis) greater than the first helix angle and less than
ninety degrees; and/or one or more of another of the cross-cut
grooves has a third helix angle (measured relative to a reference
line perpendicular to the longitudinal axis) of about ninety
degrees.
[0009] In one embodiment, each cross-cut groove passes through the
helical flight not more than two times so that the material can
back flow and recirculate within said longitudinal portion.
[0010] In one embodiment, one or more of the plurality of advancing
grooves includes an advancing groove depth taper; and/or one or
more of the plurality of cross-cut grooves having a cross-cut
groove depth taper.
[0011] The present invention also resides in another screw for a
plasticating apparatus. The plasticating apparatus includes a
barrel that has an axial length extending between an inlet port and
an outlet port. The barrel has an inner wall. The screw has a
longitudinal axis and is rotatably supported in the barrel for
rotation about the longitudinal axis. The screw has a core and one
or more helical flights extending along a length of the screw. The
helical flight defines a first helix angle relative to a reference
line perpendicular to the longitudinal axis and defines a first
helical path oriented at the first helix angle which is less than
ninety degrees. The helical flight defines a helical channel. The
screw may include a feed section cooperating with the inlet port,
an intermediate melt section, and/or a metering section cooperating
with said outlet port. A longitudinal portion of the screw (e.g.,
in the feed section, the intermediate melt section, and/or the
metering section) has a plurality of advancing grooves formed
therein. Each of the advancing grooves has one or both ends closed.
The advancing grooves are arranged in a noncontinuous helix cut in
the screw core in the helical channel of the screw. The plurality
of advancing grooves are dimensioned to receive material therein as
the material is conveyed through the helical channel, to the outlet
port. The longitudinal portion further has a plurality of
noncontinuous cross-cut grooves traversing several advancing
grooves. One or more of the plurality of advancing grooves has an
advancing groove depth taper; and/or one or more of the plurality
of cross-cut grooves has a cross-cut groove depth taper.
[0012] The present invention also resides in yet another screw for
a plasticating apparatus. The plasticating apparatus includes a
barrel that has an axial length extending between an inlet port and
an outlet port. The barrel has an inner wall. The screw has a
longitudinal axis and is rotatably supported in the barrel for
rotation about the longitudinal axis. The screw has a core and one
or more helical flights extending along a length of the screw. The
helical flight defines a first helix angle relative to a reference
line perpendicular to the longitudinal axis and defines a first
helical path oriented at the first helix angle which is less than
ninety degrees. The helical flight defines a helical channel. The
screw may include a feed section cooperating with the inlet port,
an intermediate melt section, and/or a metering section cooperating
with said outlet port. A longitudinal portion of the screw (e.g.,
in the feed section, the intermediate melt section, and/or the
metering section) has a plurality of advancing grooves formed
therein. Each of the advancing grooves has one or both ends closed.
The advancing grooves are arranged in a noncontinuous helix cut in
the screw core in the helical channel of the screw. The plurality
of advancing grooves are dimensioned to receive material therein as
the material is conveyed through the helical channel, to the outlet
port. The longitudinal portion further has a plurality of
noncontinuous cross-cut grooves traversing one or more of the
advancing grooves. The plurality of cross-cut grooves includes one
or more first cross cut grooves having a second helix angle
(measured relative to a reference line perpendicular to the
longitudinal axis) and one or more second cross-cut grooves having
a third helix angle (measured relative to a reference line
perpendicular to the longitudinal axis). The first helix angle, the
second helix angle and the third helix angle are different.
[0013] In one embodiment, the plasticating apparatus includes one
or more third cross-cut grooves having a fourth helix angle that is
different from the first helix angle, the second helix angle and
the third helix angle.
[0014] The present invention also resides in still another screw
for a plasticating apparatus. The plasticating apparatus includes a
barrel that has an axial length extending between an inlet port and
an outlet port. The barrel has an inner wall. The screw has a
longitudinal axis and is rotatably supported in the barrel for
rotation about the longitudinal axis. The screw has a core and one
or more helical flights extending along a length of the screw. The
helical flight defines a helix angle relative to a reference line
perpendicular to the longitudinal axis and defines a first helical
path of a first helix angle less than ninety degrees. The helical
flight defines a helical channel. The screw may include a feed
section cooperating with the inlet port, an intermediate melt
section, and/or a metering section cooperating with said outlet
port. A longitudinal portion of the screw (e.g., in the feed
section, the intermediate melt section, and/or the metering
section) has a plurality of advancing grooves formed therein. Each
of the advancing grooves has one or both ends closed. The advancing
grooves are arranged in a noncontinuous helix cut in the screw core
in the helical channel of the screw. The plurality of advancing
grooves are dimensioned to receive material therein as the material
is conveyed through the helical channel, to the outlet port. The
longitudinal portion further has one or more undercut surfaces
located radially inwardly from the flight surface. The undercut
surface has a depth that varies in a longitudinal direction
parallel to the advancing grooves; and/or in a direction traverse
to the longitudinal direction.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a schematic view of a portion of the surface of a
prior art screw for a plasticating apparatus;
[0016] FIG. 2 is a schematic view of a screw for a plasticating
apparatus of the present invention, shown in a cut away view of a
barrel;
[0017] FIG. 3 is a schematic view of a portion of the surface of a
screw for a plasticating apparatus of the present invention
illustrating neutrally oriented cross-cut grooves on the screw;
[0018] FIG. 4A is a schematic view of a portion of the surface of a
screw for a plasticating apparatus of the present invention
illustrating cross-cut grooves on the screw oriented in a common
direction to the flight of the screw and each cross-cut groove
cutting through one flight;
[0019] FIG. 4B is a schematic view of a portion of the surface of a
screw for a plasticating apparatus of the present invention
illustrating cross-cut grooves on the screw oriented in a common
direction to the flight of the screw and each cross-cut groove
cutting through two flights;
[0020] FIG. 5 is a schematic view of a portion of the surface of a
screw for a plasticating apparatus of the present invention
illustrating a combination of neutrally oriented cross-cut grooves
and cross-cut grooves oriented in a multiple directions;
[0021] FIG. 6 is a schematic view of a portion of the surface of a
screw for a plasticating apparatus of the present invention
illustrating advancing grooves having varying depths and depth
tapers;
[0022] FIG. 7A is a cross sectional view of a portion of the
surface of the screw of FIG. 6 taken across line 7A-7A;
[0023] FIG. 7B is a cross sectional view of another embodiment of a
portion of the surface of the screw of FIG. 6 taken across line
7B-7B;
[0024] FIG. 7C is a cross sectional view of another embodiment of a
portion of the surface of the screw of FIG. 6 taken across line
7C-7C;
[0025] FIG. 7D is a cross sectional view of another embodiment of a
portion of the surface of the screw of FIG. 6 taken across line
7D-7D;
[0026] FIG. 7E is a cross sectional view of another embodiment of a
portion of the surface of the screw of FIG. 6 taken across line
7E-7E;
[0027] FIG. 8A is a cross sectional view of one of the advancing
grooves of FIG. 6 taken across line 8A-8A showing a decreasing
depth taper;
[0028] FIG. 8B is a cross sectional view of one of the advancing
grooves of FIG. 6 taken across line 8B-8B showing constant depth
taper;
[0029] FIG. 8C is a cross sectional view of one of the advancing
grooves of FIG. 6 taken across line 8C-8C showing an increasing
depth taper;
[0030] FIG. 8D is a cross sectional view of one of the advancing
grooves of FIG. 6 taken across line 8D-8D showing varying depth
taper;
[0031] FIG. 8E is a cross sectional view of one of the advancing
grooves of FIG. 6 taken across line 8E-8E showing another varying
depth taper;
[0032] FIG. 8F is a cross sectional view of one of the advancing
grooves of FIG. 6 taken across line 8F-8F showing another varying
depth taper;
[0033] FIG. 9 is a schematic view of a portion of the surface of a
screw for a plasticating apparatus of the present invention
illustrating cross-cut grooves having varying depths and depth
tapers;
[0034] FIG. 10A is a cross sectional view of a portion of the
surface of the screw of FIG. 9 taken across line 10A-10A;
[0035] FIG. 10B is a cross sectional view of a portion of the
surface of the screw of FIG. 9 taken across line 10B-10B;
[0036] FIG. 10C is a cross sectional view of a portion of the
surface of the screw of FIG. 9 taken across line 10C-10C;
[0037] FIG. 11A is a cross sectional view of a portion of the
surface of the screw of FIG. 9 taken across line 11A-11A;
[0038] FIG. 11B is a cross sectional view of a portion of the
surface of the screw of FIG. 9 taken across line 11B-11B;
[0039] FIG. 11C is a cross sectional view of a portion of the
surface of the screw of FIG. 9 taken across line 11C-11C;
[0040] FIG. 11D is a cross sectional view of a portion of the
surface of the screw of FIG. 9 taken across line 11D-11D;
[0041] FIG. 11E is a cross sectional view of a portion of the
surface of the screw of FIG. 9 taken across line 11E-11E; and
[0042] FIG. 11F is a cross sectional view of a portion of the
surface of the screw of FIG. 9 taken across line 11F-11F.
DETAILED DESCRIPTION
[0043] Referring to FIG. 2, a plasticating apparatus is generally
designated by the numeral 200. The plasticating apparatus includes
a cylindrical barrel 2 that defines an inner surface 3. The barrel
2 includes an inlet port 4 that has a feed hopper 7 connected
thereto. The feed hopper 7 and inlet port 4 cooperate to supply one
or more solid particulate resinous materials and any additives or
agents to the barrel 2. The barrel 2 includes an outlet port 6 for
the discharge of plasticated molten extrudate to a mold or die (not
shown). Heating elements 11 are positioned outside of the barrel 2
for applying heat to the barrel 2.
[0044] As illustrated in FIG. 2, a screw 10 is axially supported
for rotation in the barrel 2 along a longitudinal axis A1. The
screw 10 extends from the inlet port 4 to the outlet port 6. The
screw 10 includes a helical flight 13 radially extending from and
winding around a core 12 in a first direction (e.g., in a right
hand threaded direction). The helical flight 13 includes a radially
outermost flight surface 14 (e.g., also referred to as a flight
land) which moves in close cooperative association with the inner
surface 3 of the barrel 2. The helical flight 13 defines a helical
channel 18 bounded by flight 13, inner surface 3 of the barrel 2
and the surface of the core 12. The depth of the helical channel 18
is measured radially from the surface of core 12 to the inner
surface 3 of the barrel 2 and is referred to as the root depth RD.
With the rotation of the screw 10, the helical channel 18 forces a
forward flow in the direction indicated by the arrow 40 of resinous
materials.
[0045] As shown in FIG. 2, the screw 10 includes a relatively deep
root feed section B for the admission, heating and working of solid
resin, a transition section C of reducing root depth to adapt to
the reduced volume of resin due to melting and the elimination of
air spaces between the solid particles, and a relatively shallow
root metering section D wherein the resin is a combination of
molten and un-melted material. The metering section D includes a
longitudinal portion A. The inlet port 4 is typically at the
rear-most part of the upstream feed section B and the outlet port 6
is the forward-most part of the downstream metering section D.
[0046] As shown in FIG. 3, the longitudinal portion A of the
surface of the core 12 includes a plurality of noncontinuous
advancing grooves 30. The advancing grooves 30 are arranged to make
a forward helical pathway in the helical channel 18. The advancing
grooves 30 are cut into the surface of core 12. There is a
plurality of adjacent grooves 30 per channel, preferably three as
shown, but not limited to only three. The advancing grooves 30 are
generally elliptically tapered. The advancing grooves 30 are
parallel to and have the same helical pitch and first helix angle
H1 as the forward helical flight 13. The first helix angle H1 is
measured relative to a reference line perpendicular to the
longitudinal axis A1. The advancing grooves 30 facilitate the
forward flow of the resinous material towards the outlet port
6.
[0047] As shown in FIG. 3, the longitudinal portion A of the
surface of the core 12 includes a plurality of staggered rows of
noncontinuous cross-cut grooves 37N cut into the surface of the
core 12 and intercept through one flight 13. The axis of each
cross-cut groove 37N is parallel to the other cross-cut grooves
37N. The cross-cut grooves 37N are oriented in a neutral direction
parallel to the longitudinal axis A1 (i.e., at about ninety degrees
relative to a reference line perpendicular to the longitudinal
axis). The cross-cut grooves 37N facilitate mixing of the resinous
material during the transport towards the outlet port 6. While the
cross-cut grooves 37N are shown and described as intercepting
through one flight 13, the present invention is not limited in this
regard as the cross-cut grooves 37N may intercept more than one
flight 13, for example, two flights 13 (e.g., both leading and
trailing flight with respect to the channel 18), as shown in FIG.
4B.
[0048] As shown in FIG. 4A, the longitudinal portion A of the
surface of the core 12 includes has a plurality of staggered rows
of noncontinuous cross-cut grooves 37C cut into the surface of the
core 12 and intercept through one flight 13. The axis of each
cross-cut groove 37C is parallel to the other cross-cut grooves
37C. While the cross-cut grooves 37C are shown and described as
being parallel to one another, the cross-cut grooves 37C may be at
different angles to one another. The cross-cut grooves 37C are
oriented in the first direction common to that of the helical
flight (i.e., a right hand threaded direction). The cross-cut
grooves 37C are oriented at a second helix angle H2 that is
different from the first helix angle H1 of the advancing grooves 30
and the helical flight 13. The second helix angle H2 shown in FIG.
4B is greater than the first helix angle H1, however in one
embodiment, the second helix angle H2 may be greater than the first
helix angle H1 and less than 90 degrees. The cross-cut grooves 37C
facilitate mixing of the resinous material during the transport
towards the outlet port 6. While the cross-cut grooves 37C are
shown and described as intercepting through one flight 13, the
present invention is not limited in this regard as the cross-cut
grooves 37C may intercept more than one flight 13, for example, two
flights 13 (e.g., both leading and trailing flight with respect to
the channel 18), as shown in FIG. 4B.
[0049] As shown in FIG. 5, the longitudinal portion A of the
surface of the core 12 includes a plurality of the cross-cut
grooves 37N and a plurality of the cross-cut grooves 37C cut into
the surface of the core 12. Each of the plurality of cross-cut
grooves 37N and each of the plurality of cross-cut grooves 37C
intersect one or both flights 13. Each of the plurality of
cross-cut grooves 37N is oriented at third helix angle H3 that is
about 90 degrees. Some of the cross-cut grooves 37C have a second
helix angle H2' and some of the cross cut grooves 37C have another
second helix angle H2'', wherein the second helix angle H2' is
different than the other second helix angle H2''. The second helix
angle H2' and the other second helix angle H2'' are greater than
the first helix angle H1 of the flight 13. The cross-cut grooves
37N and 37C facilitate mixing of the resinous material during the
transport towards the outlet port 6.
[0050] As illustrated in FIG. 6, the advancing grooves 30 have
different depths and different depth tapers along a longitudinal
axis of the advancing groove in a direction of flow Q1 in the
advancing groove. The depths are measured from the inner surface 3
of the barrel 2 to the radially inner most point of the advancing
groove 30. The different depths and different depth tapers of the
advancing grooves 30 facilitate mixing of the resinous material,
for example, by changing velocity distributions across the
advancing groove 30. As depicted in FIGS. 2 and 4A-6, the advancing
grooves 30 promote flow in the direction indicated by the arrow
40.
[0051] For example, as shown in FIG. 7A three adjacent advancing
grooves 30 have different but uniform depths D1, D2 and D3,
respectively. In one embodiment, D1 and D3 are greater than D2,
with the advancing groove 30 with the shallow depth D2 being
positioned between two advancing grooves 30 having greater depths
D1 and D3. As shown in FIGS. 7A, 7B and 7C there is an undercut
surface 66 that is formed (e.g., machine cut into) at a depth D66
which is greater than the land depth LD. Thus, the undercut surface
66 is located radially inwardly from the flight surface 14. The
undercut surface shown in FIGS. 7A, 7B and 7C has a constant depth
D66.
[0052] As shown in FIG. 7B three adjacent advancing grooves 30 have
different but uniform depths D4, D5 and D6, respectively. In one
embodiment, D5 and D6 are greater than D4, with the advancing
groove 30 with the shallow depth D4 being positioned adjacent to
the two adjacent advancing grooves 30 having greater depths D5 and
D6.
[0053] As shown in FIG. 7C three adjacent advancing grooves 30 have
different but uniform depths D7, D8 and D9, respectively. In one
embodiment, D7 and D8 are greater than D9, with the advancing
groove 30 with the shallow depth D9 being positioned adjacent to
the two adjacent advancing grooves 30 having greater depths D7 and
D8.
[0054] While the undercut surface is shown in FIGS. 7A, 7B and 7C
as having a constant depth D66, the present invention is not
limited in this regard. For example, as illustrated in FIG. 7D the
undercut surfaces have undercut groove depths that vary in a
direction traverse to the longitudinal direction along the
direction of flow Q1 including: 1) the undercut surfaces 66
adjacent to the flight 13 each have a depth D66; 2) the undercut
surface 66' has a depth D66' that is less than the depth D66 and
greater than the land depth LD; and 3) the undercut surface 66''
has a depth D66'' that is greater than the depth D66'. The traverse
change in depths of the undercut surface 66, 66' and 66''
facilitates mixing of the resinous material, for example, by
changing velocity distributions across the advancing groove 30.
[0055] In one embodiment, as shown in FIGS. 6 and 7E the undercut
surface has a varying depth in a longitudinal direction along the
direction of flow Q1, for example: 1) a portion of the undercut
surface 66 has a constant depth D66; 2) another portion of the
undercut surface 66D has an increasing depth taper along the
longitudinal direction of flow Q1 in the advancing groove 30
wherein a portion of the increasing taper has a depth D66I that is
greater than the depth D66; 3) another portion of the undercut
surface 66'' has a constant depth D66'' that is greater than the
depth D66 and the depth D66I; 4) another portion of the undercut
surface 66D has a decreasing depth taper along the longitudinal
direction of flow Q1 in the advancing groove 30 wherein a portion
of the decreasing depth taper has a depth of D66D that is less than
the depth D66''; and 5) another portion of the undercut surface 66'
has a depth D66' that is less than the depth D66.
[0056] As shown in FIG. 8A the advancing groove 30 has a decreasing
depth taper in the first direction (i.e., a longitudinal direction
along the advancing groove in a direction of flow though the
advancing groove) as indicated by the arrow Q1. For example, the
decreasing depth taper is defined by a depth D11 that is greater
than a depth D10. As shown in FIG. 8B the advancing groove 30 has a
constant depth taper in the first direction as indicated by the
arrow Q1. For example, the constant depth taper is defined by a
uniform depth D12.
[0057] As shown in FIG. 8C the advancing groove 30 has an
increasing depth taper in the first direction as indicated by the
arrow Q1. For example, the increasing depth taper is defined by a
depth D13 that is less than a depth D14.
[0058] As shown in FIG. 8D the advancing groove 30 has a varying
depth taper in the first direction as indicated by the arrow Q1.
For example, the varying depth taper is defined by: 1) a section of
decreasing depth taper wherein a depth D15' is less than a depth
D15; 2) a section of constant depth D16; 3) and a section of
increasing depth taper wherein a depth D17' is greater than a depth
D17.
[0059] As shown in FIG. 8E the advancing groove 30 has varying
depth taper in the first direction as indicated by the arrow Q1.
For example, the varying depth taper is defined by: 1) a section of
constant depth D18; 2) a section of increasing depth taper wherein
a depth D19' is greater than a depth D19; 2) a section of constant
depth D20; 4) a section of decreasing depth taper wherein a depth
D21 is less than a depth D21'; and 5) a section of constant depth
D18.
[0060] As shown in FIG. 8F the advancing groove 30 has a
continuously varying depth D22, D24 such as a wave or sinusoidal
pattern.
[0061] While the advancing grooves 30 are shown and described as
having different depths and different depth tapers, the present
invention is not limited in this regard as the cross-cut grooves
may also or in the alternative have different depths and different
depth tapers. For example, as shown in FIGS. 9, 10A, 10B, 10C, 11A,
11B, 11C, 11D, 11E, and 11F, the cross-cut grooves 37N and 37C have
different depths and different depth tapers along a longitudinal
axis of the cross-cut groove in a direction of flow Q3 in the
cross-cut grooves 37C and in the direction of flow Q2 in the
cross-cut grooves 37N. The depths are measured from the inner
surface 3 of the barrel 2 to the radially inner most point of the
cross-cut groove 37N or 37C. The different depths and different
depth tapers of the cross-cut grooves 37N and 37C facilitates
mixing of the resinous material, for example, by changing velocity
distributions across the cross-cut grooves 37N and 37C.
[0062] As shown in FIGS. 9, 10A and 11A the cross-cut groove 37C
has a constant depth D30 along the longitudinal axis of the
cross-cut groove in a direction of flow Q3. As shown in FIGS. 9,
10B and 11B the cross-cut groove 37C has a constant depth D32 along
the longitudinal axis of the cross-cut 37C groove in a direction of
flow Q3. As shown in FIGS. 9, 10C and 11C the cross-cut groove 37N
has a constant depth D33 along the longitudinal axis of the
cross-cut groove in a direction of flow Q3. The depth D30 is
greater than the depth D32 and the depth D32 is greater than the
depth D33. Thus, the cross-cut grooves 37C and the cross-cut
grooves 37N have different depths relative to other ones of the
cross-cut grooves 37C and the cross-cut grooves 37N. While, the
cross-cut grooves 37C and the cross-cut grooves 37N are shown and
described as having different depths, the present invention is not
limited in this regard as the cross-cut grooves 37C and the
cross-cut grooves 37N may have equal depths or some of the
cross-cut grooves 37C and the cross-cut grooves 37N may have equal
depths and other of the cross-cut grooves 37 and the cross-cut
grooves 37N may have different depths.
[0063] As shown in FIGS. 9, 11D, 11E and 11F, the cross-cut grooves
37C and the cross-cut grooves 37N have different depth tapers. As
shown in FIGS. 9 and 11D, the cross-cut groove 37C has an
increasing depth taper along the longitudinal axis of the cross-cut
groove 37C in a direction of flow Q3 (e.g., the cross-cut groove
37C has a depth D40 proximate one end thereof and a depth D41
proximate another end thereof, wherein the depth D41 is greater
than the depth D40). As shown in FIGS. 9 and 11E, the cross-cut
groove 37C has a decreasing depth taper along the longitudinal axis
of the cross-cut groove 37C in a direction of flow Q3 (e.g., the
cross-cut groove 37C has a depth D44 proximate one end thereof and
a depth D43 proximate another end thereof, wherein the depth D44 is
greater than the depth D43). As shown in FIGS. 9 and 11F, the
cross-cut groove 37N has a varying depth taper along the
longitudinal axis of the cross-cut groove 37C in a direction of
flow Q3. For example: 1) the cross-cut groove 37N has a depth D50
proximate one end thereof and a depth D53 adjacent thereto, wherein
the depth D53 is greater than the depth D50 thereby defining an
increasing depth taper; 2) the cross-cut groove 37N has a constant
depth D55 along a central section thereof, wherein the depth D55 is
greater than the depth D53; 3) the cross-cut groove 37N has a depth
D52 proximate another end thereof and a depth D53 adjacent thereto,
wherein the depth D53 is greater than the depth D52 thereby
defining an decreasing depth taper.
[0064] Although the invention has been described with reference to
particular embodiments thereof, it will be understood by one of
ordinary skill in the art, upon a reading and understanding of the
foregoing disclosure that numerous variations and alterations to
the disclosed embodiments will fall within the scope of this
invention and of the appended claims.
* * * * *