U.S. patent application number 15/725686 was filed with the patent office on 2018-02-01 for honeycomb ceramic substrates, honeycomb extrusion dies, and methods of making honeycomb ceramic substrates.
The applicant listed for this patent is Corning Incorporated. Invention is credited to Thomas William Brew, Jeffrey Owen Foster, Steven John Kremer, Bryan Michael Miller.
Application Number | 20180029030 15/725686 |
Document ID | / |
Family ID | 51656114 |
Filed Date | 2018-02-01 |
United States Patent
Application |
20180029030 |
Kind Code |
A1 |
Brew; Thomas William ; et
al. |
February 1, 2018 |
HONEYCOMB CERAMIC SUBSTRATES, HONEYCOMB EXTRUSION DIES, AND METHODS
OF MAKING HONEYCOMB CERAMIC SUBSTRATES
Abstract
A honeycomb ceramic substrate, a method of making thereof, and a
honeycomb extrusion die configured to extrude a honeycomb ceramic
substrate from a batch of ceramic or ceramic-forming material is
provided. The substrate may include a lattice of intersecting walls
defining a honeycomb network of flow channels extending between an
inlet end and an outlet end of the honeycomb substrate. Each flow
channel may be defined by a plurality of channel walls of the
intersecting walls with at least two of the plurality of channel
walls including concave inner surfaces facing a center of the
corresponding flow channel from central portions of the concave
inner surfaces to concave corner portions facing the center of the
corresponding flow channel.
Inventors: |
Brew; Thomas William;
(Corning, NY) ; Foster; Jeffrey Owen; (Horseheads,
NY) ; Kremer; Steven John; (Big Flats, NY) ;
Miller; Bryan Michael; (Addison, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Corning Incorporated |
Corning |
NY |
US |
|
|
Family ID: |
51656114 |
Appl. No.: |
15/725686 |
Filed: |
October 5, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
14033883 |
Sep 23, 2013 |
9808794 |
|
|
15725686 |
|
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B29C 48/345 20190201;
B29C 48/11 20190201; B01D 46/247 20130101; B01D 2046/2496 20130101;
B28B 3/269 20130101; B01J 35/04 20130101; F01N 3/2828 20130101;
C04B 38/0009 20130101; C04B 38/0009 20130101; C04B 35/00
20130101 |
International
Class: |
B01J 35/04 20060101
B01J035/04; C04B 38/00 20060101 C04B038/00; B01D 46/24 20060101
B01D046/24; B29C 47/30 20060101 B29C047/30; B28B 3/26 20060101
B28B003/26 |
Claims
1. A honeycomb extrusion die configured to extrude a honeycomb
ceramic substrate from a batch of ceramic or ceramic-forming
material, the honeycomb extrusion die comprising: a plurality of
die pins arranged in a matrix and spaced from one another to define
a lattice of intersecting slots defined between the die pins at an
outer face of the die pins, wherein an outer periphery at the outer
face of at least one of the die pins includes a plurality of sides
joined by corresponding corner portions with at least two convex
sides facing away from a center of the corresponding die pin, and
wherein at least one corner portion is convex facing away from the
center of the corresponding die pin.
2. The honeycomb extrusion die of claim 1, wherein (i) two adjacent
die pins of the plurality of die pins comprise facing sides that at
least partially define a wall slot and (ii) each facing side is
convex facing away from a center of the corresponding adjacent die
pin.
3. The honeycomb extrusion die of claim 1, wherein (i) at least one
wall slot is defined between facing sides of two adjacent die pins
of the plurality of die pins, (ii) each of the facing sides are
convex facing each other from central portions thereof to
corresponding corner portions of the facing sides, and (iii) the at
least one wall slot is concave toward central portions of the two
adjacent die pins.
4. The honeycomb extrusion die of claim 1, wherein a shape of the
outer periphery of the outer face of the at least one of the die
pins is substantially defined by the equation: x a n + y b m = 1 ,
##EQU00007## wherein a and b are rectangular-fitted half-lengths
along an x direction and a y direction, respectively, of the sides
of the die pins on either side of a y axis and an x axis,
respectively, wherein x and y represent coordinates (x, y) of the
sides of the die pins in the x direction and the y direction,
respectively, wherein -a.ltoreq.x.ltoreq.a, wherein
-b.ltoreq.y.ltoreq.b, and wherein n and m are exponents defining a
degree of curvature of the sides of the die pins.
5. The honeycomb extrusion die of claim 4, wherein at least one of
n and m is in a range of from about 2.5 to about 10.
6. The honeycomb extrusion die of claim 4, wherein a and b are
independently in a range of from about 330 microns to about 1.829
mm.
7. The honeycomb extrusion die of claim 4, wherein n and m are
varied across the plurality of the die pins.
8. The honeycomb extrusion die of claim 1, wherein the sides of
each of the die pins are symmetric to each other.
9. The honeycomb extrusion die of claim 1, wherein the sides of
each of the die pins are continuously curved around the center of
the corresponding die pin.
10. A honeycomb extrusion die configured to extrude a honeycomb
ceramic substrate from a batch of ceramic or ceramic-forming
material, the honeycomb extrusion die comprising: a plurality of
die pins arranged in a matrix and spaced from one another to define
a lattice of intersecting slots defined between the die pins at an
outer face of the die pins, wherein (i) an outer periphery at the
outer face of each of the plurality of die pins includes a
plurality of sides joined by corresponding corner portions, (ii)
two adjacent die pins of the plurality of die pins comprise facing
sides that at least partially define a wall slot, and (iii) each
facing side is convex facing away from a center of the
corresponding adjacent die pin.
11. The honeycomb extrusion die of claim 10, wherein each of the
adjacent die pins comprises a plurality of sides joined by
corresponding corner portions with at least two convex sides facing
away from a center of the corresponding adjacent die pin, and
wherein at least one corner portion is convex facing away from the
center of the corresponding adjacent die pin.
12. The honeycomb extrusion die of claim 11, wherein each of the
adjacent die pins comprises a plurality of four convex sides joined
by four corresponding convex corner portions with the four convex
sides and the four corresponding corner portions each facing away
from the center of the corresponding adjacent die pin.
13. The honeycomb extrusion die of claim 10, wherein a shape of the
outer periphery of the outer face of the adjacent die pins is
substantially defined by the equation: x a n + y b m = 1 ,
##EQU00008## wherein a and b are rectangular-fitted half-lengths
along an x direction and a y direction, respectively, of the sides
of the adjacent die pins on either side of a y axis and an x axis,
respectively, wherein x and y represent coordinates (x, y) of the
sides of the adjacent die pins in the x direction and the y
direction, respectively, wherein -a.ltoreq.x.ltoreq.a, wherein
-b.ltoreq.y.ltoreq.b, and wherein n and m are exponents defining a
degree of curvature of the sides of the adjacent die pins.
14. The honeycomb extrusion die of claim 13, wherein at least one
of n and m is in a range of from about 2.5 to about 10.
15. The honeycomb extrusion die of claim 13, wherein a and b are
independently in a range of from about 330 microns to about 1.829
mm.
16. The honeycomb extrusion die of claim 13, wherein n and m are
varied across the plurality of the adjacent die pins.
17. The honeycomb extrusion die of claim 9, wherein the sides of
each of the adjacent die pins are symmetric.
18. The honeycomb extrusion die of claim 9, wherein the sides of
each of the adjacent die pins are continuously curved around the
center of the corresponding adjacent die pin.
Description
[0001] This is a divisional application of U.S. application Ser.
No. 14/033,883 filed on Sep. 23, 2013, the content of which is
relied upon and incorporated herein by reference in its
entirety.
FIELD
[0002] The following description relates generally to substrates,
extrusion dies for making substrates and methods of making
substrates and, more particularly, to honeycomb ceramic substrates,
honeycomb extrusion dies and methods of making honeycomb ceramic
substrates.
BACKGROUND
[0003] In the automotive industry, honeycomb ceramic substrates are
often employed to support a catalyst to reduce harmful emissions
from a combustion engine. Typically, such ceramic substrates
include a lattice of walls defining flow channels including a
rectangular (e.g., square) or other cross sectional shape.
SUMMARY
[0004] In the examples described herein, a honeycomb ceramic
substrate may be created by extrusion from a batch of ceramic or
ceramic-forming material using a die with die pins arranged in a
shape designed to optimize the flow channel structure of the
resultant substrate with respect to a variety of attributes, such
as, for example, open frontal area, geometric surface area, and
strength. The optimized flow channel structure may have channel
walls with concave inner surfaces and concave corner portions,
thereby providing a flow channel structure that is, for example,
elliptical in nature. This optimized flow channel structure may
result in improved product performance in substantially all areas
of measurement, including coating efficiency by minimizing corner
coating build-up.
[0005] In a first example aspect, a honeycomb ceramic substrate
includes a lattice of intersecting walls defining a honeycomb
network of flow channels extending between an inlet end and an
outlet end of the honeycomb substrate. Each flow channel is defined
by a plurality of channel walls of the intersecting walls with at
least two of the plurality of channel walls including concave inner
surfaces facing a center of the corresponding flow channel from
central portions of the concave inner surfaces to concave corner
portions facing the center of the corresponding flow channel. The
concave corner portions are where each of the plurality of channel
walls intersects with another one of the plurality of channel
walls.
[0006] In one example of the first aspect, a peripheral
cross-sectional shape of at least one of the flow channels is
substantially defined by the equation:
x a n + y b m = 1 , ##EQU00001##
[0007] wherein a and b are rectangular-fitted half-lengths along an
x direction and a y direction, respectively, of the inner surfaces
of channel walls defining each flow channel on either side of a y
axis and an x axis, respectively,
[0008] wherein x and y represent coordinates (x, y) of the inner
surfaces of the channel walls defining each flow channel in the x
direction and the y direction, respectively,
[0009] wherein -a.ltoreq.x.ltoreq.a,
[0010] wherein -b.ltoreq.y.ltoreq.b, and
[0011] wherein n and m are exponents defining a degree of curvature
of the channel walls. In one example, at least one of n and m are
in a range of from about 2.5 to about 10. In another example, a and
b are independently in a range of from about 330 microns to about
1.829 mm. In still another example, n and m are varied across the
plurality of flow channels.
[0012] In another example of the first aspect, the channel walls
are continuously curving around the center of the corresponding
flow channel.
[0013] The first aspect may be provided alone or in combination
with any one or more of the examples of the first aspect discussed
above.
[0014] In a second example aspect, a method of making a honeycomb
ceramic substrate is provided. The method includes extruding a
ceramic or ceramic-forming batch material through a honeycomb
extrusion die to form green honeycomb substrate including a lattice
of intersecting walls defining a honeycomb network of flow channels
extending between an inlet end and an outlet end of the green
honeycomb substrate. Each flow channel is defined by a plurality of
channel walls of the intersecting walls with at least two of the
plurality of channel walls including concave inner surfaces facing
a center of the corresponding flow channel from central portions of
the concave inner surfaces to concave corner portions facing the
center of the corresponding flow channel. The concave corner
portions are where each of the plurality of channel walls
intersects with another one of the plurality of channel walls. The
method further includes drying the green honeycomb substrate, and
firing the green honeycomb substrate into the honeycomb ceramic
substrate.
[0015] In one example of the second aspect, a peripheral
cross-sectional shape of at least one of the flow channels is
substantially defined by the equation:
x a n + y b m = 1 , ##EQU00002##
[0016] wherein a and b are rectangular-fitted half-lengths along an
x direction and a y direction, respectively, of the inner surfaces
of channel walls defining each flow channel on either side of a y
axis and an x axis, respectively,
[0017] wherein x and y represent coordinates (x, y) of the inner
surfaces of the channel walls defining each flow channel in the x
direction and the y direction, respectively,
[0018] wherein -a.ltoreq.x.ltoreq.a,
[0019] wherein -b.ltoreq.y.ltoreq.b, and
[0020] wherein n and m are exponents defining a degree of curvature
of the channel walls. In one example, at least one of n and m is in
a range of from about 2.5 to about 10. In another example, a and b
are independently in a range of from about 330 microns to about
1.829 mm. In another example, n and m are varied across the
plurality of the flow channels.
[0021] In another example of the second aspect, the channel walls
are continuously curved around the center of the corresponding flow
channel.
[0022] The second aspect may be provided alone or in combination
with any one or more of the examples of the second aspect discussed
above.
[0023] In a third example aspect, a honeycomb extrusion die
configured to extrude a honeycomb ceramic substrate from a batch of
ceramic or ceramic-forming material is provided. The honeycomb
extrusion die includes a plurality of die pins arranged in a matrix
and spaced from one another to define a lattice of intersecting
slots defined between the die pins at an outer face of the die
pins. An outer periphery at the outer face of at least one of the
die pins includes a plurality of sides joined by corresponding
corner portions with at least two convex sides facing away from a
center of the corresponding die pin from central portions of the
convex sides to the corresponding corner portions of the convex
sides. At least one corner portion is convex facing away from the
center of the corresponding die pin.
[0024] In one example of the third aspect, at least one wall slot
is defined between facing sides of two adjacent die pins of the
plurality of die pins. Each of the facing sides are convex facing
each other from central portions thereof to corresponding corner
portions of the facing sides. The wall slot is concave toward
central portions of the two adjacent die pins.
[0025] In another example of the third aspect, a shape of the outer
periphery of the outer face of the at least one of the die pins is
substantially defined by the equation:
x a n + y b m = 1 , ##EQU00003##
[0026] wherein a and b are rectangular-fitted half-lengths along an
x direction and a y direction, respectively, of the sides of the
die pins on either side of a y axis and an x axis,
respectively,
[0027] wherein x and y represent coordinates (x, y) of the sides of
the die pins in the x direction and the y direction,
respectively,
[0028] wherein -a.ltoreq.x.ltoreq.a,
[0029] wherein -b.ltoreq.y.ltoreq.b, and
[0030] wherein n and m are exponents defining a degree of curvature
of the sides of the die pins. In one example, at least one of n and
m is in a range of from about 2.5 to about 10. In another example,
a and b are independently in a range of from about 330 microns to
about 1.829 mm. In another example, n and m are varied across the
plurality of the die pins.
[0031] In a further example of the third aspect, the sides of each
of the die pins are symmetric to each other.
[0032] In still a further example of the third aspect, the sides of
each of the die pins are continuously curved around the center of
the corresponding die pin.
[0033] The third aspect may be provided alone or in combination
with any one or more of the examples of the third aspect discussed
above.
BRIEF DESCRIPTION OF THE DRAWINGS
[0034] The above and other features, aspects and advantages of the
present disclosure are better understood when the following
detailed description of the disclosure is read with reference to
the accompanying drawings, in which:
[0035] FIG. 1 is a perspective view illustrating an example of a
honeycomb ceramic substrate in accordance with example aspects of
the disclosure;
[0036] FIG. 2 is a schematic sectional view illustrating an example
of the honeycomb ceramic substrate in accordance with example
aspects of the disclosure along line 2-2 of FIG. 1;
[0037] FIG. 3 is an enlarged view illustrating an example of the
honeycomb ceramic substrate in accordance with example aspects of
the disclosure taken at view 3 of FIG. 2;
[0038] FIG. 4 is an enlarged view of FIG. 3;
[0039] FIG. 5 is an enlarged view of FIG. 4;
[0040] FIGS. 6-12 are enlarged views similar to FIG. 3 but
illustrating various alternative example honeycomb ceramic
substrate configurations;
[0041] FIG. 13 is a graphical view illustrating an example of an
impact of exponents defining a degree of curvature of a flow
channel of the honeycomb ceramic substrate on a change in inertia
of the flow channel in accordance with example aspects of the
disclosure;
[0042] FIG. 14 is a graphical view illustrating an example of an
impact of exponents defining a degree of curvature of a flow
channel of the honeycomb ceramic substrate on a resistance of the
flow channel to chipping as evidenced by an effective additional
web attachment length in accordance with example aspects of the
disclosure;
[0043] FIG. 15 is a enlarged view illustrating an example of the
honeycomb ceramic substrate in accordance with example aspects with
respect to effective additional channel wall thickness;
[0044] FIG. 16 is a graphical view illustrating an example of an
impact of exponents defining a degree of curvature of a flow
channel of the honeycomb ceramic substrate on a percentage of
reduction in an open frontal area of the flow channel in accordance
with example aspects of the disclosure;
[0045] FIG. 17 is a graphical view illustrating an example of an
impact of exponents defining a degree of curvature of a flow
channel of the honeycomb ceramic substrate on an effective corner
radius for washcoat efficiency of the flow channel in accordance
with example aspects of the disclosure;
[0046] FIG. 18 is a flow diagram illustrating an example of a
method of making a honeycomb ceramic substrate in accordance with
example aspects of the disclosure;
[0047] FIG. 19 is a schematic view illustrating an example of an
extrusion apparatus in accordance with example aspects of the
disclosure;
[0048] FIG. 20 is an enlarged partial schematic sectional view
illustrating an example of a die member in accordance with example
aspects of the disclosure taken at view 20 of FIG. 19;
[0049] FIG. 21 is a partial sectional view of the die member along
line 21-21 of FIG. 20;
[0050] FIG. 22 is an enlarged view of portions of FIG. 21; and
[0051] FIGS. 23-25 are enlarged views illustrating examples of the
honeycomb ceramic substrate in accordance with example aspects of
the disclosure.
DETAILED DESCRIPTION
[0052] The disclosure will now be described more fully hereinafter
with reference to the accompanying drawings in which example
embodiments are shown. Whenever possible, the same reference
numerals are used throughout the drawings to refer to the same or
like parts. However, the disclosure may be embodied in many
different forms and should not be construed as limited to the
embodiments set forth herein. These example embodiments are
provided so that this disclosure will be both thorough and
complete.
[0053] FIG. 1 is a perspective view illustrating an example of a
honeycomb ceramic substrate 102. The honeycomb ceramic substrate
102 is not necessarily drawn to scale and illustrated only one
example schematic representation of a honeycomb ceramic substrate
102. The honeycomb ceramic substrate 102 includes an inlet end 104
and an outlet end 106 positioned opposite from the inlet end 104. A
lattice of intersecting walls defining a honeycomb network of flow
channels 108 extend between the inlet end 104 and outlet end 106.
In one example, substantially all of the flow channels 108 are not
plugged and therefore provide for an unobstructed pass flow from
the inlet end 104 to the outlet end 106 of the honeycomb ceramic
substrate 102.
[0054] FIG. 2 is a schematic sectional view illustrating an example
of the honeycomb ceramic substrate 102 in accordance with example
aspects of the disclosure along line 2-2 of FIG. 1. As shown in
FIG. 2, the flow channels 108 can be formed by a plurality of
channel walls 110 of the intersecting walls extending
longitudinally between the inlet end 104 and outlet end 106 of the
honeycomb ceramic substrate 102. The flow channels 108 and the
channel walls 110 can each extend in a substantially parallel
orientation longitudinally between the inlet end 104 and the outlet
end 106. As further illustrated, the honeycomb ceramic substrate
102 may include an outer skin defining an outer surface 112 that
can extend longitudinally between the inlet end 104 and outlet end
106. As shown, the outer surface 112 can comprise a circular
cylindrical shape having a circular cross-sectional profile. In
further examples, the outer surface 112 may have an elliptical,
polygonal or other shape. For example, although not shown, the
outer surface 112 may have a polygonal shape such as triangular,
rectangular (e.g., square) or other polygonal shape. Moreover, as
shown, the honeycomb ceramic substrate 102 can comprise a single
monolithic substrate although the substrate may comprise a
segmented substrate wherein many substrates are mounted parallel to
one another to provide the desired overall cross sectional
configuration. Whether a single monolithic or segmented substrate,
various geometries may be incorporated in accordance with aspects
of the disclosure. For example, the substrates may comprise a
rectangular (e.g., square) cross-sectional outer periphery or other
polygonal shape having three or more sides. In further examples,
the substrates may have an outer cross-sectional periphery that is
circular, oval, or other curved shape.
[0055] The honeycomb ceramic substrate 102 can have a variety of
cell densities, such that a larger or smaller number of flow
channels 108 can be provided per unit area. For instance, the
channel density can be in the range of from about 7.75
channels/cm.sup.2 (50 channels/in.sup.2) to about 232.5
channels/cm.sup.2 (1500 channels/in.sup.2) of the honeycomb ceramic
substrate 102 cross-section. As such, the examples shown in FIGS. 1
and 2 are not intended to be limiting, as various ranges of cell
densities may be provided in accordance with aspects of the
disclosure.
[0056] In further examples, the channel wall constructions forming
the flow channels 108 can have different configurations. FIG. 3 is
an enlarged view illustrating an example of the honeycomb ceramic
substrate 102 in accordance with example aspects of the disclosure
taken at view 3 of FIG. 2. For illustration purposes, FIG. 3 shows
a grouping of nine flow channels 108. FIG. 4 is an enlarged view of
FIG. 3 illustrating an example of a flow channel 108 of the
honeycomb ceramic substrate 102 in accordance with example aspects
of the disclosure. FIG. 5 is an enlarged view of FIG. 4,
illustrating demonstrating further features of the example flow
channel 108. FIGS. 6-12 are enlarged views of alternative honeycomb
ceramic substrates 102a-g, respectively, that are similar to the
honeycomb ceramic substrate 102 of FIGS. 3-5 but illustrating
various alternative flow channel 108a-g configurations in
accordance with aspects of the disclosure. In each of the example
honeycomb ceramic substrates, for example as illustrated in FIGS.
1-12, the flow channel structure may have channel walls with
concave inner surfaces and concave corner portions. Indeed, the
channel walls including concave inner surfaces and concave corner
portions are noticeably shown in FIGS. 1-6 and 10, and would also
be more noticeably illustrated in enlarged views of the channel
walls and corner portions of the flow channel structure illustrated
in FIGS. 7-9, 11 and 12. This optimized flow channel structure may
result in improved product performance in substantially all areas
of measurement, including coating efficiency by minimizing corner
coating build-up.
[0057] In the examples shown in FIGS. 3-12, each flow channel 108,
108a-g is defined by a plurality of intersecting channel walls 110
with at least two of the plurality of channel walls 110 including
concave inner surfaces 116 facing a center 125 of the corresponding
flow channel 108 from central portions 120 of the concave inner
surfaces 116 to concave corner portions 118 facing the center 125
of the corresponding flow channel 108. The concave corner portions
118 are where each of the plurality of channel walls 110 intersects
with another one of the plurality of channel walls 110. The
arrangement of flow channels 108 illustrated in FIGS. 3-6 and 10
are generally elliptical with concave channel walls 110 and the
concave corner portions 118 continuously curving around the center
125 of the corresponding flow channel 108. Further examples, e.g.,
as illustrated in FIGS. 7-9, 11 and 12, may have flow channels 108
with a square-like or rectangle-like configuration with concave
channel walls 110 and concave corner portions 118 continuously
curving around the center 125 of the corresponding flow channel
108.
[0058] As mentioned above, the flow channels 108 of the honeycomb
ceramic substrate 102 may be a superellipse, also known as a Lame
curve, generally elliptical or even square-like or rectangular-like
with concave channel walls and concave corner portions in order to
obtain an optimized flow channel shape for an open frontal area
(OFA) and a geometric surface area (GSA) of the flow channels 108.
By controlling the length of the channel walls 110 and a degree of
curvature of the channel walls 110 and corner portions 118, various
desired flow channel shapes may be obtained. For example, a
peripheral cross-sectional shape of at least one of the flow
channels 108 may be substantially defined by Equation (I).
x a n + y b m = 1 ( I ) ##EQU00004##
[0059] As is illustrated in FIGS. 4 and 5, a and b are
rectangular-fitted half-lengths along an x direction and a y
direction, respectively, of the inner surfaces 116 of channel walls
110 defining each flow channel 108 on either side of a y axis and
an x axis, respectively. In other words, a and b represent the
half-lengths along an x and y direction, respectively, if the
channel walls 110 were truly straight to provide a square or
rectangular flow channel 108. The dimensions a and b serve to
define the density of flow channels 108 and the channel wall 110
thickness between the flow channels 108 in the honeycomb ceramic
substrate 102. The references x and y represent coordinates (x, y)
of the inner surfaces 116 of the channel walls 110 defining each
flow channel 108 in the x direction and the y direction,
respectively. Further, -a.ltoreq.x.ltoreq.a and
-b.ltoreq.y.ltoreq.b. Moreover, n and m are exponents defining a
degree of curvature of the channel walls 110.
[0060] In an example, at least one of n and m may be in a range of
from about 2.5 to about 10. In another example, a and b may be
independently in a range of from about 330 microns (0.013 inches)
to about 1.829 mm (0.072 inches). In a further example, a thickness
of the plurality of channel walls 110 between adjacent ones of the
flow channels 108 may be in a range of from about 25.4 microns
(0.001 inches) to about 482.6 microns (0.019 inches).
[0061] In yet another example, the channel walls 110 in each flow
channel 108 may have substantially identical lengths. In further
examples, at least two of the channel walls 110 in each flow
channel 108 may have a length that is the same. Additionally, the
channel walls 110 of each flow channel 108 may be symmetric to each
other.
[0062] Equation (I) results in a flow channel 108 having gently
curved inner surfaces 116 with more pronounced curved corners 118.
Even with corners 118 that have a more pronounced curvature than
the gently curved inner surfaces 116, each of the channel walls 110
of the flow channels 108 are continuously curved toward a center
125 of the corresponding flow channel 108 throughout the length of
the channel wall between corresponding concave corner portions. In
further examples, the entire inner surface of the flow channel is
continuously concave about the entire periphery of the flow
channel, wherein the inner surface is defined by gently concave
channel walls 110 and more pronounced concave corner portions 118
that seemlessly transition with one another about the inner
periphery of the inner surface of the flow channels.
[0063] The exponents n and m of Equation (I) are tuned, depending
on the flow channel density and a thickness of the channel walls
110 between adjacent flow channels, to meet the above-referenced
attributes in order to minimize coating buildup in the corner
portions 118 and maximize open frontal area. The examples
illustrated in FIGS. 6-12 demonstrate the power that an adjustment
of the exponents n and m may implement on a curvature degree of the
flow channels 108 and a concavity of the inner surfaces 116. More
particular, FIGS. 6-12 illustrate that, according Equation (I), the
concavity of the inner surfaces 116 may be maintained at the same
time a curvature degree of the flow channels 108a-g is
decreased.
[0064] For example, FIGS. 6-9 are representative of honeycomb
ceramic substrates 102a-g having a flow channel density of 69.75
channels/cm.sup.2 (450 channels/in.sup.2) and a thickness of the
plurality of channel walls 110 between adjacent ones of the flow
channels 108 of 635 microns (0.025 inches). However, FIGS. 6-9 each
represent honeycomb ceramic substrates 102 in which exponents n and
m have been tuned. FIG. 6 represents a honeycomb ceramic substrate
102a with n and m equaling 3.6. FIG. 7 represents a honeycomb
ceramic substrate 102b with n and m equaling 4.0. FIG. 8 represents
a honeycomb ceramic substrate 102c with n and m equaling 10. FIG. 9
represents a honeycomb ceramic substrate 102d with n and m equaling
50. As can be seen by a comparison of FIGS. 6-9, both a degree to
which a flow channel 108 is curved and a concavity of the inner
surfaces 116 can be changed by varying the exponents n and m.
[0065] FIGS. 10 and 11 are representative of honeycomb ceramic
substrates 102e-f having a flow channel density of 93
channels/cm.sup.2 (600 channels/in.sup.2) and a thickness of the
plurality of channel walls 110 between adjacent ones of the flow
channels 108 of 571.5 microns (0.0225 inches). However, FIG. 10
represents a honeycomb ceramic substrate 102e with n and m equaling
3.6, while FIG. 11 represents a honeycomb ceramic substrate 102f
with n and m equaling 42.
[0066] FIG. 12 represents a honeycomb ceramic substrate 102 having
a flow channel density of 62.78 channels/cm.sup.2 (405
channels/in.sup.2) and a thickness of the plurality of channel
walls 110 between adjacent ones of the flow channels 108 of 1.0668
mm (0.042 inches). However, FIG. 12 represents a honeycomb ceramic
substrate 102 with n equaling 4 and m equaling 8, thereby producing
flow channels 108 with a rectangular-like shape, rather than a
square-like shape.
[0067] The concavity of the inner surfaces 116 may compensate for
some of the open area of the flow channel 108 that is lost due to
the curved flow channel shape. Flow channel density and the
thickness of the channel walls 110 between adjacent flow channels
108 may additionally be selected to optimize flow channel shape for
a desired GSA. Further, the concavity of the inner surfaces 116 may
provide the flow channels 108 with increased strength and
resistance to buckling and rotational failures by increasing a
moment of inertia, or decreasing a slenderness ratio, of each of
the channel walls 110. This increased strength may afford reduced
thicknesses of the channel walls 110 between adjacent flow channels
108, thereby further optimizing open frontal area and reduction of
weight of the honeycomb ceramic substrate 102.
[0068] In an example, Table 1 compares square flow channels in a
honeycomb ceramic substrate having a channel density of 93
channels/cm.sup.2 (600 channels/in.sup.2) with elliptical flow
channels in a honeycomb ceramic substrate having n and m equal to
3.5 with a channel density of 93 channels/cm.sup.2 (600
channels/in.sup.2).
TABLE-US-00001 TABLE 1 Flow Channel Density 93 channels/cm.sup.2 93
channels/cm.sup.2 (600 channels/in.sup.2) (600 channels/in.sup.2)
Square n and m = 3.5 Channel Wall Thickness 76.2 microns 76.2
microns Between Flow Channels (0.003 inches) (0.003 inches)
Equivalent Fillet Radius 76.2 microns 254 microns of Channel Walls
(0.003 inches) (0.01 inches) MIF (uncoated) 0.69 1.24
[0069] While an equivalent fillet radius of the channel walls is
greater in the elliptical flow channel than in the square flow
channel, a mechanical integrity factor (MIF) of the elliptical flow
channel is greater than an MIF of the square flow channel. The MIF,
represented by Equation (II) below, is a dimensionless structural
property that is directly proportional to a load carrying
capability parallel to the channel walls and along a diagonal of
the flow channel, where "t" is the channel wall thickness between
flow channels, "l" is the distance between channel wall centers,
and "R" is the effective corner radius, as is illustrated in FIGS.
4 and 5. The MIF is derived by equating a maximum bending stress at
a midpoint of the channel walls or at an intersection of the
channel walls to channel wall strength.
MIF*100=t1*(t/(l-t-2*R))*100 (II)
[0070] Further, the equivalent fillet radius of the channel walls
is defined by the group of equations listed below in Table 2, where
"a", "b", and "c" represent the three sides of a triangle, "A" is
the area of the triangle, and "r" is the equivalent fillet radius
of the channel walls.
Table 2
[0071] a=sqrt((x1-x2).sup.2+(y1-y2).sup.2)
b=sqrt((x2-x3).sup.2+(y2-y3).sup.2)
a=sqrt((x3-x1).sup.2+(y3-y1).sup.2)
s=(a+b+c)/2
A=sqrt(s*(s-a)*(s-b)*(s-c))
r=a*b*c/(4*A)
[0072] Table 3 compares other strength advantages of elliptical
flow channels over square flow channels based on other product
variants. For example, a slenderness ratio is used to compare the
strength of the channel walls. Smaller slenderness ratios are more
resistant to failures at equivalent loadings. Additionally to be
noted is the fact that the channel wall thickness between the
elliptical flow channels is less than the channel wall thickness
between the square flow channels. When the square and elliptical
flow channels having equivalent flow channel densities are
compared, the elliptical flow channel having a thinner channel wall
has a lower slenderness ratio than the comparable square flow
channel having a thicker channel wall. In other words, the
elliptical flow channel designs have the lower slenderness ratios,
which indicates a higher resistance to buckling loading. Buckling
failure is often seen in the extrusion of substrates having thin
channel walls when adjacent channel wall velocities are not
uniform. Buckling failure is one of the principle reasons for
rejected extruded ware.
TABLE-US-00002 TABLE 3 Flow Channel 93 93 69.75 62 62 139.5 139.5
Density - (600) (600) (450) (400) (400) (900) (900)
channels/cm.sup.2 (channels/in.sup.2) Channel Wall 88.9 57.15 57.15
88.9 106.68 68.58 57.15 Thickness (0.0035) (0.00225) (0.00225)
(0.0035) (0.0042) (0.0027) (0.00225) Between Flow Channels -
microns (inches) Flow Channel Square Elliptical Elliptical Square
Square Square Elliptical Shape Distance 1.036 1.036 1.197 1.270
1.270 0.847 0.847 Between (0.0408) (0.0408) (0.04714) (0.05) (0.05)
(0.03333) (0.03333) Channel Wall Centers - mm (inches) Radius of
269.2 342.9 403.9 315.0 327.7 215.9 241.3 Gyration X - (0.0106)
(0.0135) (0.0159) (0.0124) (0.0129) (0.0085) (0.0095) microns
(inches) Slenderness 1.92 1.51 1.48 2.02 1.94 1.96 1.75 Ratio
[0073] The Slenderness Ratio is the quotient of the distance
between the channel wall centers, the radius of gyration around the
x-axis, and 2. The Slenderness Ratio is applied to determine the
critical buckling stress 6 between the channel wall centers, as is
shown in Equation (III) below.
.sigma.=.pi..sup.2E/(Slenderness Ratio).sup.2 (III)
[0074] where E is the Young's modulus of the channel wall
material.
[0075] FIG. 13 is a graphical view illustrating an example of an
impact of exponents defining a degree of curvature of a flow
channel of the honeycomb ceramic substrate on a change in inertia
of the flow channel in accordance with example aspects of the
disclosure. As shown FIG. 13, the vertical axis is the percent
change in inertia while the horizontal axis demonstrates the
exponents m and n (that are the same). Change in inertia is a
measurement used to determine resistance of a flow channel to
buckling of the channel walls. For example, when a flow channel has
a higher percentage of change in inertia, it is more likely to be a
stronger flow channel and have channel walls that are less subject
to buckling. It is noted an elliptical flow channel having a lower
value of m and n has a greater percentage of change in inertia.
[0076] FIG. 14 is a graphical view illustrating an example of an
impact of exponents defining a degree of curvature of a flow
channel of the honeycomb ceramic substrate on a resistance of the
flow channel to chipping as evidenced by an effective additional
channel wall thickness attachment length in accordance with example
aspects of the disclosure. As shown in FIG. 14, the vertical axis
is the effective additional channel wall thickness attachment
length (in inches) and the horizontal axis demonstrates the
exponents m and n (that are the same). Example attachment lengths
are schematically illustrated in FIG. 15. For example, when the
channel wall thickness has an effective additional attachment
length L2 of 127 microns (0.005 inches) or greater, a clear
resistance to chipping is shown when compared to smaller attachment
lengths L1. It is noted that an elliptical flow channel having a
lower value of m and n has a greater effective additional
attachment length.
[0077] FIG. 16 is a graphical view illustrating an example of an
impact of exponents defining a degree of curvature of a flow
channel of the honeycomb ceramic substrate on a percentage of
reduction in an OFA of the flow channel in accordance with example
aspects of the disclosure. As shown in FIG. 16, the vertical axis
is the percent difference in open area while the horizontal axis
demonstrates the exponents m and n (that are the same). While lower
n and m values promote greater strength in flow channels than
higher n and m values, FIG. 16 demonstrates that higher n and m
values provide a greater flow channel OFA, which relates to the
catalyst performance of a flow channel.
[0078] FIG. 17 is a graphical view illustrating an example of an
impact of exponents defining a degree of curvature of a flow
channel of the honeycomb ceramic substrate on an effective corner
radius for washcoat efficiency of the flow channel in accordance
with example aspects of the disclosure. As shown in FIG. 17, the
vertical axis is the effective corner radius (inches) while the
horizontal axis demonstrates the exponents m and n (that are the
same). For example, measurements of coated substrates show a
minimum of a 254 micron (0.010 inch) washcoat radius after coating.
It is noted that an elliptical flow channel having a lower value of
m and n has a greater uniformity of washcoat coating.
[0079] In addition, Table 4 highlights several performance
attributes of an elliptical flow channel having a channel density
of 69.75 channels/cm.sup.2 (450 channels/in.sup.2), a channel wall
thickness between flow channels of 63.5 microns (0.0025 inches),
and m and n values equal to 3.6 in comparison with alternative
hexagonal and square flow channels. Of note, the elliptical flow
channel substantially matches the hexagonal flow channel's exhaust
performance characteristics while providing close to 40% increased
strength over the hexagonal flow channel.
TABLE-US-00003 TABLE 4 Elliptical, n Flow Channel Shape Hexagonal
Square and m = 3.6 Flow Channel 93 93 69.75 Density - (600) (600)
(450) channels/cm.sup.2 (channels/in.sup.2) Channel Wall 76.2 76.2
63.5 Thickness Between (0.003) (0.003) (0.0025) Flow Channels -
microns (inches) Equivalent Fillet 76.2 76.2 304.8 Radius of
Channel (0.003) (0.003) (0.012) Walls - microns (inches) OFA
(coated) 0.84 0.78 0.84 GSA (coated) 31.6 35.3 31.3 MIF (uncoated)
0.46 0.69 0.64 Resistance to Flow 491 709 452 (RTF) (coated)
[0080] The OFA, the GSA, and RTF are calculated as is provided in
Equations (IV), (V), and (VI) below, respectively. The OFA is used
to compare substrates for back pressure. The GSA is used to compare
substrates for conversion efficiency. For example, a higher GSA
translates into a higher conversion efficiency or capability for
the substrate. The RTF is a measure of the resistance to flow
through the channels.
OFA=(1-t/L).sup.2-(4-.pi.)(R/L).sup.2 (IV) [0081] where "t" is the
channel wall thickness between flow channels, "L" is the distance
between channel wall centers, and "R" is the effective corner
radius, as is illustrated in FIGS. 4 and 5.
[0081] GSA=(4(L-t)/L.sup.2)-(((8-2.pi.)R)/L.sup.2) (V) [0082] where
"t" is the channel wall thickness between flow channels, "L" is the
distance between channel wall centers, and "R" is the effective
corner radius, as is illustrated in FIGS. 4 and 5.
[0082] RTF=2f/((OFA*Dh.sup.2)w) (VI) [0083] where "f" is the
fanning friction factor, "Dh" is the hydraulic diameter of the flow
channel, and "w" is the width
[0084] Table 5 highlights further variants of the elliptical flow
channel concept. As Table 5 shows, the elliptical flow channel is
designed to allow thinner channel wall thicknesses while
maintaining equivalent product strength and improving OFA and GSA
on a 900 channel/inch.sup.2 substrate.
TABLE-US-00004 TABLE 5 Flow Channel Shape Square Elliptical Flow
Channel Density - 139.5 139.5 channels/cm.sup.2 (900) (900)
(channels/in.sup.2) Channel Wall Thickness 68.58 57.15 Between Flow
Channels - (0.0027) (0.00225) microns (inches) Equivalent Fillet
Radius 50.8 124.46 of Channel Walls - (0.002) (0.0049) microns
(inches) OFA (coated) 84.2 86 GSA (coated) 43.3 43.8 MIF (uncoated)
0.74 0.72 RTF (coated) 867 857
[0085] Equation (I) may also be translated into x and y coordinates
to yield Equation (VII) and Equation (VIII), respectively.
x ( t ) = .+-. a cos ( t ) ( 2 n ) where a = a for 0 .ltoreq. t
.ltoreq. .pi. 2 and 3 .pi. 2 .ltoreq. t .ltoreq. 2 .pi. ; a = - a
for .pi. 2 < t < 3 .pi. / 2 ( VII ) y ( t ) = .+-. b sin ( t
) ( 2 m ) where b = b for 0 .ltoreq. t .ltoreq. .pi. and b = - b
for .pi. < t < 2 n ( VIII ) ##EQU00005##
[0086] FIG. 18 is a flow diagram illustrating an example of a
method 300 of making a honeycomb ceramic substrate in accordance
with example aspects of the disclosure. FIG. 19 is a schematic view
illustrating an example of an extrusion apparatus 400 in accordance
with example aspects of the disclosure. FIG. 20 is an enlarged
partial schematic sectional view illustrating an example of a
honeycomb extrusion die 408 in accordance with example aspects of
the disclosure taken at view 20 of FIG. 19.
[0087] Referring to FIGS. 18-20, the method 300 includes extruding
302 a ceramic or ceramic-forming batch material 402 through a
honeycomb extrusion die 408 to form green honeycomb substrate of
potentially unlimited length. The extruding 302 may be performed by
introducing the ceramic or ceramic-forming batch material 402 into
an input portion 404 of an extruding device 406. Once the desired
length is achieved, a cutter (not shown) can be used to sever the
extruded ceramic or ceramic-forming substrate to provide the
substrate with the desired length.
[0088] As shown, in one example, the extruding device 406 can
include a twin-screw extruder including twin screws 410a, 410b
configured to be rotated by respective motors 412a, 412b to mix and
compress the batch 402 of ceramic or ceramic-forming batch material
as it travels along a path 414 toward the honeycomb extrusion die
408. The extruding device 406 includes an extrusion axis wherein
the ceramic-forming substrate can be extruded from the honeycomb
extrusion die 408 along an extrusion direction substantially
parallel to the extrusion axis.
[0089] As shown in FIG. 20, the die member 408 includes feed holes
416 configured to feed batch material 402 in direction 418, along
the path 414, toward a plurality of die pins 420. The die pins 420
are arranged in a matrix and spaced apart from one another to
define a lattice of intersecting slots 422 defined between the die
pins 420 at an outer face of the die pins 420. As shown in FIGS.
21-22, an outer periphery 501 at an outer face 503 of at least one
of the die pins 420 includes a plurality of sides 505a-d joined by
corresponding corner portions 507a-d with at least two convex sides
facing away from a center 509 of the corresponding die pin 420 from
central portions of the convex sides to the corresponding end
portions of the convex sides. At least one corner portion 507a-d is
convex facing away from the center 509 of the corresponding die pin
420. The slots 422 are designed to form the channel walls 110 of
the honeycomb ceramic substrate 102 as the ceramic-forming batch
material 402 is drawn into the honeycomb ceramic substrate 102.
[0090] At least one wall slot 422 may be defined between facing
sides (e.g., 505a/505c, 505b/505d, 505c/505a, 505d/505b) of two
adjacent die pins of the plurality of die pins 420. As shown, each
of the facing sides may be convex facing each other from central
portions thereof to corresponding end portions of the facing sides.
Consequently, the wall slot 422 defined therebetween, may be
concave toward central portions of the two adjacent die pins.
[0091] For example, with reference to the die pin shown in FIG. 22,
a shape of the outer periphery 501 of the outer face 503 of one of
the die pins 420 can be substantially defined by Equation (I).
x a n + y b m = 1 ( I ) ##EQU00006##
[0092] As is somewhat inversely illustrated in FIGS. 4 and 5, a and
b are rectangular-fitted half-lengths along an x direction and ay
direction, respectively, of the sides 505a-d of the die pins 420 on
either side of a y axis and an x axis, respectively. x and y
represent coordinates (x, y) of the sides of the die pins 420 in
the x direction and the y direction, respectively. Further,
-a.ltoreq.x.ltoreq.a and -b.ltoreq.y.ltoreq.b. Moreover, n and m
are exponents defining a degree of curvature of the sides of the
die pins 420.
[0093] In an example, at least one of n and m may be in a range of
from about 2.5 to about 10. In another example, a and b may be
independently in a range of from about 330 microns (0.013 inches)
to about 1.829 mm (0.072 inches). In a further example, the die
pins 420 may be arranged in the matrix and spaced from one another
to have a die pin density in a range of from about 7.75 die
pins/cm.sup.2 (50 die pins/in.sup.2) to about 232.5 die
pins/cm.sup.2 (1500 die pins/in.sup.2). In an additional example, a
thickness of the intersecting slots 422 between adjacent ones of
the die pins 420 may be in a range of from about 25.4 microns
(0.001 inches) to about 482.6 microns (0.019 inches).
[0094] In yet another example, the sides of each of the die pins
420 may have a length that is the same. Further, at least two of
the sides of each of the die pins 420 may have a length that is the
same. In still another example, the sides of each of the die pins
420 may be symmetric to each other. In addition, the sides and
corner portions of each of the die pins 420 may be continuously
curved around the center of the corresponding die pin 420.
[0095] In addition, the shape of the die pin 420 either may be the
same or varied along an entire length of the die pin 420. For
example, the shape of the die pin 420 on the outer face 503 may
extend a depth of 127 microns (0.005 inches) from the outer face
503 along the length of the die pin 420, with the remaining length
of the die pin 420 being formed in a different shape. In another
example, the shape of die pin 420 on the outer face 503 may extend
a depth of 30% to 50% of the length of the die pin 420 from the
outer face 503 along the length of the die pin 420 while the
remaining length of the die pin 420 is formed in a different shape.
For instance, in one example, the die pins may be formed by
Electrical Discharge Machining (EDM) wire machining the entire
length of the die pin. After forming the initial die pin shape, a
subsequent machining step may be carried out by plunge EDM
machining an electrode having the desired shape of the die pin at
the outer face of the die pin. In such examples, the plunge EDM may
extend a depth of 127 microns (0.005 inches) and/or to a depth of
from about 30% to about 50% of the length of the die pin. As such,
the shape of the die pin at the outer face may comprise the shape
of the electrode while the remaining shape is defined by the
initial wire EDM machining procedure.
[0096] Turning back to FIG. 18, the method 300 can further include
the step of drying 304 the green honeycomb substrate. Additionally,
the method 300 can include the step of firing 306 the green
honeycomb substrate into the honeycomb ceramic substrate 102.
[0097] FIGS. 23-25 are enlarged views illustrating examples of the
honeycomb ceramic substrate 102 in accordance with example aspects
of the disclosure. Referring to FIGS. 23-25, the honeycomb ceramic
substrate 102 is illustrated having flow channels 108 and channel
walls 110 of varied shape and size. For example, exponents m and n
of Equation (I) can be varied across the die pins 420 of a
honeycomb extrusion die 408 to create a honeycomb ceramic substrate
102 with varying thicknesses of the channel walls 110 and varying
areas of the flow channels 108.
[0098] Referring to FIG. 23, as an example, values of m and n may
be decreased progressively from an internal portion of the
honeycomb ceramic substrate 102 to a periphery of the honeycomb
ceramic substrate 102. Such a design may serve to strengthen a
peripheral portion of the honeycomb ceramic substrate 102 while
maintaining a thickness of the channel walls 110 across the
honeycomb ceramic substrate 102. The example illustrated in FIG. 24
shows that the values of m and n may also be increased
progressively from an internal portion of the honeycomb ceramic
substrate 102 to a periphery of the honeycomb ceramic substrate
102. This may provide a more uniform gas flow in a catalytic
chamber by manipulating the OFA of the flow channels 108. In
addition, as is illustrated in FIG. 25, exponents m and n can be
increased or decreased abruptly in a specific section of the
honeycomb ceramic substrate 102. This may serve to increase
strength in the specific section of the honeycomb ceramic substrate
102 in which such an abrupt change is applied.
[0099] It will be apparent to those skilled in the art that various
modifications and variations can be made to the present disclosure
without departing from the spirit and scope of the disclosure.
Thus, it is intended that the present disclosure cover the
modifications and variations of this disclosure provided they come
within the scope of the appended claims and their equivalents.
* * * * *