U.S. patent application number 15/017766 was filed with the patent office on 2016-06-02 for coated pelletizing extrusion dies and method for making the same.
The applicant listed for this patent is Kennametal Inc.. Invention is credited to Sudhir Brahmandam, Dave Richard Siddle, Irene Spitsberg.
Application Number | 20160151952 15/017766 |
Document ID | / |
Family ID | 47911538 |
Filed Date | 2016-06-02 |
United States Patent
Application |
20160151952 |
Kind Code |
A1 |
Brahmandam; Sudhir ; et
al. |
June 2, 2016 |
COATED PELLETIZING EXTRUSION DIES AND METHOD FOR MAKING THE
SAME
Abstract
A pelletizing extrusion die comprising a die body contains a
plurality of extrusion holes. Each of the extrusion holes is
defined by a defining surface of the die body wherein at least a
portion of the defining surface has a low-friction coating
deposited thereon. A method for applying the low-friction coating
to the defining surface wherein the applying step occurs at a
temperature equal to less than about 520.degree. C.
Inventors: |
Brahmandam; Sudhir; (Irwin,
PA) ; Siddle; Dave Richard; (Greensburg, PA) ;
Spitsberg; Irene; (Export, PA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Kennametal Inc. |
Latrobe |
PA |
US |
|
|
Family ID: |
47911538 |
Appl. No.: |
15/017766 |
Filed: |
February 8, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13525536 |
Jun 18, 2012 |
9314985 |
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15017766 |
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13246137 |
Sep 27, 2011 |
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13525536 |
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Current U.S.
Class: |
427/135 |
Current CPC
Class: |
B29C 48/04 20190201;
B29C 48/35 20190201; B29C 48/2528 20190201; B29C 48/345 20190201;
B30B 11/228 20130101; B29C 48/3003 20190201; B30B 11/221 20130101;
Y10S 425/23 20130101; B29C 48/05 20190201; B29C 48/0022 20190201;
B30B 11/202 20130101; B29B 9/06 20130101; B29K 2909/04 20130101;
B29C 48/3001 20190201; B60J 10/17 20160201; B29K 2905/08
20130101 |
International
Class: |
B29C 47/08 20060101
B29C047/08; B29C 47/32 20060101 B29C047/32 |
Claims
1. A method of coating a defining surface of a pelletizing
extrusion die body contains a plurality of extrusion holes, and
wherein each of the extrusion holes being defined by the defining
surface of the die body, the method comprising the steps of:
applying a low-friction coating to at least a portion of the
defining surface at a temperature equal to less than about
520.degree. C.
2. The method according to claim 1 wherein pelletizing extrusion
die plate comprising any one of the following: steels, stainless
steels, and superalloys.
3. The method according to claim 1 wherein the low-friction coating
comprising any one of the following: metal, ceramic or
composite.
4. The method according to claim 1 wherein the low-friction coating
has coefficient of friction equal to less than about 0.5.
5. The method according to claim 1 wherein the die body having a
inner face and an outer face, the defining surface having a
generally frusto-conically shaped entrance section adjacent to the
inner face and an exit section extending from the entrance section
to the outer face, and wherein the applying step applies the
low-friction coating to only the entrance section of the defining
surface,
6. The method according to claim 1 wherein the pelletizing
extrusion die body has an inner face, and the applying step further
included applying the low-friction coating to at least a portion of
the inner face.
7. A method of coating at least a portion of a defining surface of
a cylindrical pelletizing extrusion body having an inner
cylindrical face and an outer face, and the cylindrical pelletizing
extrusion die body further containing a plurality of extrusion
holes extending radially through the cylindrical pelletizing
extrusion die body, and wherein each of the extrusion holes being
defined by the defining surface of the cylindrical extrusion die
body wherein the defining surface having a generally
frusto-conically shaped unobstructed entrance section adjacent to
the inner cylindrical face and an exit section extending from the
entrance section to the outer face, the method comprising step of:
applying a metallurgically-bonded low-friction coating having a
substantially constant thickness, on the entrance section of the
defining surface and the exit section of the defining surface.
8. The method according to claim 7 wherein the
meteallurgically-bonded low-friction coating has coefficient of
friction equal to less than about 0.5.
9. The method according to claim 7 wherein the
metallurgically-bonded low-friction coating being on at least a
part of the inner cylindrical face.
10. The method according to claim 7 wherein the cylindrical die
body comprising any one of the following: steel. stainless steel
and superalloy.
11. The method according to claim 7 wherein the
metallurgically-bonded low-friction coating comprising any one of
the following: metal, ceramic or composite.
12. The method according to claim 7 wherein the
metallurgically-bonded low-friction coating has a thickness equal
to be between about 20 microns and about 200 microns.
13. A method of coating at least a portion of a defining surface of
a cylindrical pelletizing extrusion body having an inner
cylindrical face and an outer face, and the cylindrical pelletizing
extrusion die body further containing a plurality of extrusion
holes extending radially through the cylindrical pelletizing
extrusion die body, and wherein each of the extrusion holes being
defined by the defining surface of the cylindrical extrusion die
body wherein the defining surface having a generally
frusto-conically shaped unobstructed entrance section adjacent to
the inner cylindrical face and an exit section extending from the
entrance section to the outer face, the method comprising step of:
applying a metallurgically-bonded low-friction coating having a
substantially constant thickness, on the exit section of the
defining surface.
Description
CROSS-REFERENCE TO EARLIER PATENT APPLICATION
[0001] This patent application is a divisional patent application
of pending U.S. patent application Ser. No. 13/525,536, filed Jun.
18, 2012 for COATED PELLETIZING EXTRUSION DIES AND METHOD FOR
MAKING THE SAME by Sudir Brahmadam, Dave Siddle, and Irene
Spitsberg, which is a continuation-in-part of U.S. patent
application Ser. No. 13/246,137, filed on Sep. 27, 2011 for COATED
PELLETIZING DIES by Sudir Brahmadam, David Richard Siddle, and
Irene Spitsberg, and wherein the above-referenced U.S. patent
application Ser. No. 13/246,137 and above-referenced U.S. patent
application Ser. No. 13/525,536 are each hereby incorporated by
reference herein their entirety herein. Applicants hereby claim
priority from the aforesaid parent patent application (i.e., U.S.
patent application Ser. No. 13/246,137, filed on Sep. 27, 2011 for
COATED PELLETIZING DIES) and the aforesaid CIP patent application
(i.e., U.S. patent application Ser. No. 13/525,536, filed Jun. 18,
2012 for COATED PELLETIZING EXTRUSION DIES AND METHOD FOR MAKING
THE SAME) under the United States Patent Statute (Title 35)
including 35 USC .sctn..sctn.120.
FIELD OF THE INVENTION
[0002] The present invention relates to pelletizing extrusion dies,
as well as to a method for making a pelletizing extrusion die. More
particularly, the present invention pertains to a coated
pelletizing extrusion die and a method for making a coated
pelletizing extrusion die.
BACKGROUND INFORMATION
[0003] Conventional pelletizing processes generally use a plate or
ring with many holes of various shapes that are used to form a
pellet from a material that is forced into the holes. The material
travels through the holes and exits at the other end, where it is
cut to size by knives. Such extrusion of the material generally
requires a large amount of force as the material drags on the
entrance face and then the sides of the holes, producing some level
of heating due to this work. The pelletizing process relies on some
level of friction between the raw material and the die surfaces in
order to compress the raw material to a higher density as it is
extruded. However, excessive friction results in excessive heat,
which can cause burning or oxidation of the material resulting in
scrap.
[0004] One type of pelletizing operation uses a rotary extruder to
mix and transport the materials to a die plate containing shaped
holes that form the pellets. Another type of pelletizing operation
uses a ring die that has mating rolls that force the material
radially through the pelletizing holes from the inside to the
outside of the ring die. As the extruded material exits the die,
the strands may be cut by a knife, or set of knives, passing along
the surface of the die face immediately upon exiting the die. These
types of ring dies are typically cylindrical in shape with
diameters ranging, for example, from about 16 inches (40.64
centimeters) to 72 inches (182.88 centimeters). The body of the die
includes hundreds to thousands of holes throughout to facilitate
the extrusion process. The diameters of the holes can range, for
example, from about 1 mm to about 25 mm. These plate and ring
extrusion dies may be used in a number of applications, such as
pelletizing pet and animal feed, and wood pelletizing for bio-fuel
applications.
[0005] A critical problem with these types of dies, however, is the
loss of pellet quality with increasing cycles and premature
mechanical failure of the die by cracking through the wall
thickness in a radial orientation. While such failures could
possibly be explained as the result of wear of the inner surface of
the ring and the hole, failure analysis of the dies has revealed
that, while wear of the inner surface of the extrusion die and the
holes may occur, this is not the reason for the loss of pellet
quality or the failure of the die by cracking. It has been found
that the unanticipated reason for these failures is related to
friction, as more fully described below.
[0006] During operation of conventional pelletizing ring extrusion
dies, friction causes the temperature to increase, which causes
volatile constituents in the slurry to vaporize or evaporate more
quickly. This causes viscosity variations in the slurry, which in
turn causes inconsistent flow and finally results in poor pellet
quality. This inconsistent slurry flow causes the material to build
up inside the die and increases the stress needed to extrude the
slurry through the passageways. The increase in temperature and
stress accelerate the fatigue crack growth in the die. The root
cause of the loss of pellet quality and premature cracking of the
dies is therefore mainly due to the friction at the entrance
chamfer to the pelletizing holes. A decrease in the friction on the
lead-in chamfer section would minimize the problems associated with
the increased temperature and increase the die life and the pellet
quality.
[0007] There are several approaches to control the friction of
various types of surfaces. These include self-lubricating surfaces,
where a liquid or solid lubricant is entrapped in the surface pores
or features. Various low friction ceramic or cermet coatings may be
deposited by various coating/cladding technologies. However,
modifying or enhancing the surface in a manner that will not
degrade the substrate properties while maintaining the low friction
characteristics needed in this application is a challenge. A major
problem with applying self lubricating surfaces in extrusion dies
is that either the soft lubricating material will be consumed
quickly by the extruding slurry, or the pores on the steel surface
needed to retain the lubricant decrease the mechanical strength of
the steel and can cause premature failure of the die.
[0008] While there are several coating/cladding techniques
available to deposit low friction coatings, these technologies have
their own problems including degradation of the substrate
properties and poor dimensional control. For example, techniques
such as thermal spray and plasma transfer arc do not work because
the high heat input distorts the parts which then must be
corrected, resulting in a high priced solution. Chemical vapor
deposition (CVD) and physical vapor deposition (PVD) techniques are
not considered because of the limited thickness of the state of the
art technology and dimensional distortion caused by the high
deposition temperatures. Traditional CVD technologies are limited
to deposition temperatures greater than 800.degree. C. Other
technologies such as cladding or dip coating have also been
unsuccessful as they plug the holes and/or distort the parts due to
the high heat input during the process.
[0009] It would be highly desirable to provide an improved
pelletizing die that demonstrates improved properties, such as
lower friction on the chamfer region, with adequate wear resistance
to maintain the chamfer profile and a method of manufacturing
thereof.
SUMMARY OF THE INVENTION
[0010] The present invention provides coated pelletizing extrusion
dies with improved life. Low-friction coatings are provided on the
inner surface of the die and at the entrance and at part of the
surface of the extrusion holes. The coatings limit the increase in
surface temperature during use of the die.
[0011] In one form thereof, the invention is a pelletizing
extrusion die that comprises a die body. The die body contains a
plurality of extrusion holes. Each of the extrusion holes is
defined by a defining surface of the die body wherein at least a
portion of the defining surface has a low-friction coating
deposited thereon.
[0012] In another form thereof, the invention is a pelletizing
extrusion die that comprises a die body. The die body contains a
plurality of extrusion holes. Each of the extrusion holes is
defined by a defining surface of the die body which has a
low-friction coating deposited thereon.
[0013] In yet another form thereof, the invention is a method of
coating a defining surface of a pelletizing extrusion die body
contains a plurality of extrusion holes, and wherein each of the
extrusion holes is defined by the defining surface of the die body.
The method comprises the step of applying a low-friction coating to
at least a portion of the defining surface at a temperature equal
to less than about 520.degree. C.
[0014] These and other aspects of the present invention will be
more apparent from the following description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is an isometric view of a pelletizing ring extrusion
die that may be coated in accordance with an embodiment of the
present invention
[0016] FIG. 2 is a partially schematic top view of a pelletizing
ring extrusion die in operation in accordance with an embodiment of
the present invention.
[0017] FIG. 3 is a cross-sectional view of a portion of a
pelletizing ring extrusion die assembly in accordance with an
embodiment of the present invention.
[0018] FIG. 4 is a sectional view of extrusion holes of a
pelletizing ring die coated with a low-friction coating in
accordance with an embodiment of the present invention.
[0019] FIG. 5 is a top view of a pelletizing extrusion die
plate.
[0020] FIG. 5A is a cross-sectional view of the pelletizing
extrusion die plate of FIG. 5 taken along section line 5A-5A of
FIG. 5.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
[0021] The present invention provides pelletizing dies having a
low-friction coating on at least a portion thereof. The pelletizing
die may be made of any suitable material. For example, the
pelletizing die may be made of stainless steel, carbon steel, or
superalloys. In some embodiments, the die may be made of CA6NM, a
300 or 400 series of stainless steel, 4140, 4340 or similar alloy,
Inconel or Hastealloy, or a similar nickel-based alloy. The
pelletizing die typically has a hardness of 45-55 RC, A strength of
1.3-2.1 GPa, toughness of greater than 27 N-m, and an endurance
limit of at least 680 MPa. The pelletizing die may be made by any
process as appreciated by one skilled in the art, such as casting,
welding, machining from wrought material or powder metallurgical
methods.
[0022] FIGS. 1 and 2 illustrate an embodiment of a ring pelletizing
die (or pelletizing ring extrusion die) 10 for use with a
conventional extruder that may be partially coated with a
low-friction coating in accordance with an embodiment of the
invention. As shown most clearly in FIG. 1, the ring pelletizing
die 10 comprises a cylindrical die body 12 having a top groove 14,
a bottom groove 16, and a die working area 18 therebetween. The die
working area 18 comprises a plurality of small holes or bores 20
that may be generally similar or identical in configuration. The
small holes 20 are extrusion passageways for the material feed. The
small holes 20 extend in a radial direction through the die body 12
from an inner face 22 of the die working area 18 to an outer face
24 of the die working area 18.
[0023] FIGS. 2 and 3 illustrate the use of the pelletizing die 10
of the invention in a pellet mill 50. During the process, material
is fed inside the pelletizing die 10 and roller assembly rolls 54
are used to distribute the material across the inner face 22 of the
die body 12. The material is extruded through the holes 20 from the
inner face 22 of the die working area 18 surface and is pushed
outwardly by the rolls 54 through to the outer face 24 of the die
body 12.
[0024] As illustrated in FIGS. 3 and 4, the small holes 20 include
an inlet end opening 26 having a tapered portion or chamfer 30 and
a generally cylindrical passageway section 32 extending therefrom
to an outlet end opening 34. The extrusion passageways or
passageway section 32 may present different geometric
configurations in shape and diameter size as well as may present
different configurations within the same die body.
[0025] According to the invention, an inner surface 36 of the small
holes 20 have a low-friction coating 40 on at least a portion
thereon. The low-friction coating 40 may be at least along the
tapered portion 30 of the inner surface 36 of the hole 20. In other
embodiments, the low-friction coating 40 may extend beyond the
tapered portion 30 on the inner surface 36 of the small holes 20.
In yet other embodiments, the low-friction coating 40 may be on the
entire inner surface 36 of the holes 20. The low-friction coating
40 may also cover the entire inner face 22 of the die 10.
[0026] The low-friction coating 40 may comprise any material that
exhibits low friction while having sufficient wear and corrosion
and erosion properties. In some embodiments, the low-friction
coating 40 may include tungsten carbide materials. In other
examples, the low-friction coating may be an ultralow friction
diamond-like carbon (DLC), molybdenum disulphide,
Ti--Si--Cr--C--N-based coatings, or WC/W based coatings.
[0027] The low-friction coating 40 may be at least 20 microns thick
on the inner surface 36 of the holes 20. For example, the coating
thickness may be at least 25 microns, at least 50 microns, at least
100 microns, or at least 200 microns thick. In aspects of the
invention, the low-friction coating thickness may be 25 microns to
75 microns, or 35 microns to 55 microns. The as-applied coating may
have toughness properties that allow it to demonstrate no visible
spalling on elastically deformed substrate areas during operation.
The wear resistance properties of the coated part according to ASTM
G65 (ASTM G65-04(2010) ["Standard Test Method for Measuring
Abrasion Using the Dry Sand/Rubber Wheel Apparatus"]) testing can
be greater than 30 or 40 times that of an uncoated substrate.
[0028] In aspects of the invention, the low-friction coating 40 may
be comprised of a single layer or multiple layers. In an embodiment
of multiple layers, each layer may be one of a metal, ceramic, or
composite. Examples of metal layers includes Ti, Cr, Zr or Hf.
Examples of ceramic layers may include TiN, TiCN, TiAlN, TiAlSiCN
or WC. Examples of composite layers include WC-W, TiSiCN
nanocomposite structures, SiCN, WC--Co, WC--Ni, Ni-diamond and the
like.
[0029] The low-friction coating 40 may be applied to the inner
surface of the small holes 20 by metallurgically bonding the
coating to a substrate by processes appreciated by those skilled in
the art. Deposition from vapor phase, chemical deposition or
deposition from liquid media like slurry or chemical solutions may
be used.
[0030] In aspects of the invention, the coating may be applied by a
PVD technique by rotating a cathode inside the ring during the
deposition. Examples of PVD techniques include magnetron
sputtering, arc deposition or plasma enhanced PVD-CVD hybrids, such
as plasma enhanced magnetron sputtering and the like.
[0031] Alternatively, the coating may be deposited by a low
temperature or plasma enhanced CVD technique. In certain
embodiments, the PVD and/or CVD deposition of the coating does not
occur at temperatures greater than 600.degree. C., and may occur
around 500.degree. C., such as 450-520.degree. C. The as-applied
coating on the inner surface of the small holes 20 preferably
results in a similar surface finish as the inner surface of the
hole without a coating. Preferably, the low-friction coating does
not result in any visible defects such as visible flaws, flaking or
exposed surfaces and has a consistency of color over the coated
portion of the inner surface of the small holes. In embodiments,
after applying the coating, the coated portion of the small holes
20 may undergo further processing such as polishing.
[0032] One preferred embodiment is a pelletizing ring extrusion die
where the substrate is made of stainless steel, coated at a
temperature of 450-520.degree. C. with a 20-200 .mu.m thick TiSiCN
or WC/W coating, with a friction coefficient in the 0.2 to 0.6
range. Preferably, the deposition temperature is <490.degree. C.
and the coating thickness is 30-70 .mu.m. The coating is preferably
on the chamfered portion of the hole and extends some length into
the passageway and also on the inner surface of the die. FIG. 4
illustrates the low-friction coating 40 on the inner face (or
surface) 22 of the pelletizing ring extrusion die 10.
[0033] The low-friction coating 40 preferably has a coefficient
friction of less than 0.6, typically less than 0.5. For example,
the friction coefficient may be from 0.05 to 0.4 or 0.5. Here, the
friction coefficient is measured according to ASTM G99-05(2010)
["Standard Test Method for Wear Testing with a Pin-on-Disk
Apparatus". In accordance with the present invention, the coating
being a low friction material, acts to reduce heat buildup during
the pelletizing process. The reduction in the heat buildup in the
die can serve to extend the life as the strength of the metal of
the die is maintained at a higher level, providing an improved
fatigue crack initiation resistance and longer service life from a
fatigue related failure.
[0034] The low-friction coating provides a means for reducing
friction loading and lowering operation temperatures, resulting in
improved material flow and metal strength that extends the fatigue
life. This lower friction level is accompanied by a corresponding
resistance to abrasion and erosion. Otherwise, the coating will be
worn away too quickly and fail to provide an adequate means to
reach a longer life span. A secondary effect of the coating applied
to the entrance portion of the pelletizing holes is that the lower
friction may reduce the amount of hole plugging which can lead to
reduced life due to the higher stresses experienced as the material
is blocked from entering a section or region of the die where
plugging has occurred. These higher stresses are caused by a
thicker layer of raw material that cannot pass through the plugged
holes, causing an increase in the radial pressure on the ring die
that leads to higher hoop stresses in the die metal.
[0035] FIG. 5 is a top view of a pelletizing extrusion die plate
generally designated as 80. Pelletizing extrusion die plate 80 has
a die plate body 81. The die plate body 81 contains a plurality of
supporting bolt holes 82 and a plurality of extrusion (or
pelletizing) holes 84. The die plate body 81 has an inner face 86
and an outer face 88. FIG. 5A is a sectional view of a portion of
the pelletizing extrusion die plate body 81 taken along section
line 5A-5A of FIG. 5. FIG. 5A shows the geometry of an extrusion
hole 84. Extrusion hole 84 has an entrance end 90 and an exit end
92. A generally frusto-conically shaped entrance section 94 is
adjacent the entrance end 90 of the extrusion hole 84. A generally
cylindrically shaped exit section 96 extends from the entrance
section 94 to the exit end 92, which is adjacent to the outer face
88. As shown in FIG. 5A, a low-friction coating 98 is on the
surface that defines the generally frusto-conically shaped entrance
section 94. During the process using the pelletizing extrusion die
plate 80, the material is fed along an extruder barrel that ends
with the die plate 80 wherein the material is extruded through the
extrusion holes 84 from the inner face 86 and is pushed outwardly
through to the outer face 88 of the pelletizing extrusion die plate
80. The presence of the low-friction coating 98 on the surface
defining the generally frusto-conically shaped entrance section 94
helps reduce friction during the extrusion process. There should be
an understanding that the low-friction coating 98 can also be
located on all or a part of the surface defining the exit section
96 of the extrusion hole 84. Further, the low-friction coating 98
may be located on the inner face 88 of the pelletizing extrusion
die plate 80.
[0036] Two coatings were tested against a benchmark, which is a
uncoated 420C stainless steel. Coating A was a TiSiCN
coating--PVD-based (Plasma Enhanced Magnetron Sputtering) PEMS
coating as described in publication application US2009/0214787 A1,
which is incorporated herein by reference. The coating was greater
than 50 microns thick. The coating was deposited at
.about.450.degree. C. on ASTM G65 and ASTM G99 test coupons of
SS420 steel. Coating B was WC/W--CVD-based coating as described in
U.S. Pat. No. 4,427,445, which is incorporated herein by reference.
The coating thickness was greater than 50 microns on the substrate.
The coating was deposited at .about.500.degree. C. on ASTM G65 and
ASTM G99 test coupons of SS420 steel in a low temperature CVD
furnace. The samples were tested for resistance to acids by
immersing them in HCl, H.sub.2SO.sub.4 and HF in a standard
chemical immersion test with the reactivity measured by weight
change and visual appearance. The friction coefficient was tested
using a alumina ball with a .about.1 GPa stress using the ASTM
099-05(2010) ["Standard Test Method for Wear Testing with a
Pin-on-Disk Apparatus"] test method. The wear resistance was
determined using the ASTM G65-04(2010) ["Standard Test Method for
Measuring Abrasion Using the Dry Sand/Rubber Wheel Apparatus"] test
method. The results are given in Table 1 below. As seen in the
table, Coatings A and B showed a good combination of low
temperature deposition, low friction and good wear resistance.
TABLE-US-00001 TABLE 1 Test Results for Uncoated Steel and Two
Coatings (TiSiCN and WC/W) Benchmark Coating Coating B Uncoated
SS420 A (TiSiCN) (WC/W) Resistance to Acids acceptable Good Good
Friction Coefficient 0.7 0.2-0.5 0.3-0.4 (ASTM G99) Processing -NA-
400-450.degree. C. 480-520.degree. C. Temperature Wear Base line
(1X) >10-40X over >10-40X over Resistance uncoated 400
uncoated 400 (ASTM G65) series SS series SS
[0037] The pelletizing extrusion die of the invention may be used
for a number of different applications and provides a number of
advantages. For example, such applications include pelletizing
operations of food/feed for human and animal consumption as well as
for recycling products such as plastic pellets and wood pellets.
The coated pelletizing extrusion die also provides excellent
abrasion and erosion resistance thereby increasing wear resistance
of the die. The invention also eliminates and/or minimizes further
finishing of the pelletizing extrusion die.
[0038] It is to be understood that this disclosure is not limited
to the particular methodologies and materials described, as these
may vary. It is also to be understood that the terminology used in
the description is for the purpose of describing the particular
versions or embodiments only, and is not intended to limit the
scope. For example, as used herein and in the appended claims, the
singular forms "a", "an", and "the" include plural references
unless the context clearly dictates otherwise. For example, while
reference is made herein to "a" die, "a" coating, "a" roll, and the
like, one or more of these or any other components can be used. In
addition, the word "comprising" as used herein is intended to mean
"including but not limited to". Unless defined otherwise, all
technical and scientific terms used herein have the same meanings
as commonly understood by one of ordinary skill in the art.
[0039] The patents and other documents identified herein are hereby
incorporated by reference herein.
[0040] Whereas particular embodiments of this invention have been
described above for purposes of illustration, it will be evident to
those skilled in the art that numerous variations of the details of
the present invention may be made without departing from the
invention as defined in the appended claims. Other embodiments of
the invention will be apparent to those skilled in the art from a
consideration of the specification or a practice of the invention
disclosed herein. It is intended that the specification and
examples are illustrative only and are not intended to be limiting
on the scope of the invention. The true scope and spirit of the
invention is indicated by the following claims.
* * * * *