U.S. patent application number 14/392179 was filed with the patent office on 2016-06-30 for method for producing honeycomb structures.
The applicant listed for this patent is SUMITOMO CHEMICAL COMPANY, LIMITED. Invention is credited to Hiroyuki IKAWA, Masashi INOUE, Teruo KOMORI.
Application Number | 20160185010 14/392179 |
Document ID | / |
Family ID | 52141626 |
Filed Date | 2016-06-30 |
United States Patent
Application |
20160185010 |
Kind Code |
A1 |
IKAWA; Hiroyuki ; et
al. |
June 30, 2016 |
METHOD FOR PRODUCING HONEYCOMB STRUCTURES
Abstract
A plurality of inlet-side octagonal cells and outlet-side
quadrangular cells partitioned by partition walls on an upper
surface and a lower surface are opened in a green honeycomb molded
body in which a plurality of through-holes partitioned from each
other by the partition walls are open in an end surface of a
columnar body. Four outlet-side quadrangular cells having a smaller
opening area adjoin around one inlet-side octagonal cell through
the partition walls. The partition walls are joined together and
the inlet-side octagonal cells are opened while closing the
outlet-side quadrangular cells on the inlet side and the
outlet-side quadrangular cells are opened while closing the
inlet-side octagonal cells on the outlet side in a
particulate-matter-removing filter such as a diesel particulate
filter.
Inventors: |
IKAWA; Hiroyuki;
(Tsukuba-shi, Ibaraki, JP) ; INOUE; Masashi;
(Niihama-shi, Ehime, JP) ; KOMORI; Teruo;
(Niihama-shi, Ehime, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SUMITOMO CHEMICAL COMPANY, LIMITED |
Tokyo |
|
JP |
|
|
Family ID: |
52141626 |
Appl. No.: |
14/392179 |
Filed: |
May 30, 2014 |
PCT Filed: |
May 30, 2014 |
PCT NO: |
PCT/JP2014/064504 |
371 Date: |
December 23, 2015 |
Current U.S.
Class: |
55/523 ;
264/320 |
Current CPC
Class: |
B28B 1/08 20130101; B01D
2046/2481 20130101; B28B 1/093 20130101; B01D 46/0001 20130101;
B01D 46/2459 20130101; B28B 11/006 20130101 |
International
Class: |
B28B 1/093 20060101
B28B001/093; B01D 46/24 20060101 B01D046/24; B01D 46/00 20060101
B01D046/00; B28B 11/00 20060101 B28B011/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 28, 2013 |
JP |
2013-136587 |
Claims
1. A method for producing a honeycomb structure comprising a
plurality of through-holes that open in an end surface of a
columnar body and are mutually partitioned by partition walls, a
part of the plurality of through-holes having been closed, the
method comprising: a closing step of closing a part of the
through-holes by joining the partition walls in a green honeycomb
molded body together at the end surface, wherein the green
honeycomb molded body in which a part of the through-holes are
closed at the closing step includes, at the end surface, one first
through-hole and four second through-holes that have a smaller
opening area than the first through hole and adjoin around the one
first through-hole with the partition walls provided
therebetween.
2. The method for producing a honeycomb structure according to
claim 1, wherein the first through-hole is octagonal and the second
through-hole is quadrangular.
3. The method for producing a honeycomb structure according to
claim 1, wherein the first through-hole has a round quadrangular
shape with a corner of the quadrangle being rounded, and the second
through-hole has a quadrangular shape.
4. The method for producing a honeycomb structure according to
claim 1, wherein, at the closing step, the second through-hole is
closed at one of the end surfaces, and the first through-hole is
closed at another end surface.
5. The method for producing a honeycomb structure according to
claim 1, wherein, at the closing step, a closing tool is inserted
into a part of the plurality of through-holes in the green
honeycomb molded body to join the partition walls together at the
end surface to close the through-holes.
6. The method for producing a honeycomb structure according to
claim 5, wherein, at the closing step, in closing the second
through-holes, the closing tool including any one shape of a
quadrangular pyramid and a quadrangular pyramid platform is
inserted into the first through-hole while allowing a lateral edge
of the closing tool to abut against each of the partition walls
that adjoin the second through-holes to close the second
through-holes.
7. The method for producing a honeycomb structure according to
claim 5, wherein, at the closing step, in closing the first
through-hole, the closing tool including any one shape of a
quadrangular pyramid and a quadrangular pyramid platform is
inserted into each of the second through-holes while allowing a
lateral edge of the closing tool to abut against the partition
walls that adjoin the first through-hole to close the first
through-hole.
8. A honeycomb structure produced by the method according to claim
1.
Description
TECHNICAL FIELD
[0001] An aspect of the present invention relates to a method for
producing honeycomb structures and also relates to a method for
producing honeycomb structures in which a green honeycomb molded
body is fired to produce a honeycomb structure.
BACKGROUND ART
[0002] For example, honeycomb hole structures made of ceramic and
having a plurality of through-holes of a cross-section polygonal
shape are conventionally known. Such honeycomb structures are used,
for example, in particulate-matter-removing filters such as diesel
particulate filters. In a production step of such honeycomb
structures, a ceramic raw material powder is formed by extruding to
produce a green honeycomb molded body. A part of through-holes in
this green honeycomb molded body are closed at an end surface. A
honeycomb structure is produced by firing the green honeycomb
molded body with closed through-holes. Patent Literature 1
discloses a method for producing such honeycomb structures. In
Patent Literature 1, a sealing material is pressed with a piston
against one end of a honeycomb structure placed within a cylinder
to supply the sealing material to the end of through-holes in the
honeycomb structure and to close the through-holes.
CITATION LIST
Patent Literature
[0003] PTL 1: Japanese Examined Patent Publication No.
S63-24731
SUMMARY OF INVENTION
Technical Problem
[0004] However, in the method in the above Patent Literature 1,
sealing materials such as sealing pastes are necessary. Further,
Patent Literature 1 has the problem that it requires a very
troublesome step, for example, applying a sealing mask to an end
surface and opening a hole at a place to be closed in the mask.
[0005] In the technical field, production methods in which sealing
pastes are not needed and which can simply close the end of a
honeycomb structure, and honeycomb structures obtained by those
production methods have been desired.
Solution to Problem
[0006] One aspect of the present invention is a method for
producing a honeycomb structure, the method comprising a closing
step of joining together partition walls of a green honeycomb
molded body in which a plurality of through-holes partitioned by
partition walls are open to each other at the end surface of a
columnar body to close a part of the through-holes, wherein the
green honeycomb molded body in which a part of the through-holes
are closed at the closing step includes, at the end surface, one
first through-hole and four second through-holes that have a
smaller opening area than the first through hole and that adjoin
around the first through-hole with the partition wall provided
between the first through-hole and the second through-holes.
[0007] With this construction, it is unnecessary to use sealing
pastes, such as in conventional methods, and the end of honeycomb
structures can be simply closed. Further, since cells are closed by
welding cell walls together, when the honeycomb structure is used
in diesel particulate filters, turbulence of flow of exhaust gases
at the end surface on the exhaust gas supply side is reduced and
pressure loss can be reduced.
[0008] In this case, the first through-hole may be octagonal, and
the second through-holes may be quadrangular.
[0009] According to this construction, the first through-hole is
octagonal, and the second through-holes are quadrangular. For this
reason, for example, when the quadrangular through-holes adjoin
every other side of the octagonal through-hole, through-holes
having a different size can be arranged in the end surface.
[0010] Further, the first through-hole may have a round
quadrangular shape with a corner of the quadrangle being rounded,
and the second through-hole may have a quadrangular shape.
[0011] According to this construction, the first through-hole has a
round quadrangular shape with the corner of the quadrangle being
rounded, and the second through-hole has a quadrangular shape. For
this reason, for example, when the quadrangular through-hole
adjoins each of the four sides of the round quadrangular
through-hole, through-holes having a different size can be arranged
in the end surface.
[0012] Further, at the closing step, the second through-hole can be
closed at one of the end surfaces and the first through-hole can be
closed at the other end surface.
[0013] According to this construction, at the closing step, the
second through-holes are closed at one of the end surfaces, and the
first through-holes are closed at the other end surface. For this
reason, for example, when the honeycomb structure is applied to a
particulate-matter-removing filter such as a diesel particulate
filter, when first through-holes having a large opening area are
open while closing the second through-holes having a small opening
area on an inlet side of the particulate-matter-removing filter,
and the second through-holes having a small opening area are open
while closing the first through-holes having a large opening area
on an outlet side, the inlet side becomes wide and pressure loss in
a state in which soot is deposited can be reduced.
[0014] Further, at the closing step, by inserting a closing tool
into a part of a plurality of through-holes in the green honeycomb
molded body, partition walls are joined together at the end surface
and the through-holes can be closed.
[0015] According to this construction, at the closing step, by
inserting a closing tool into a part of the plurality of
through-holes in the green honeycomb molded body, the partition
walls are joined together at the end surface to close the
through-holes. Thus, the closing of the through-holes can very
easily be carried out.
[0016] In this case, at the closing step, in closing the second
through-holes, by inserting a closing tool including any one shape
of a quadrangular pyramid and a quadrangular pyramid platform into
the first through-hole while allowing the lateral edge of the
closing tool to abut against each of the partition walls that
adjoin the second through-holes, the second through-holes can be
closed.
[0017] According to this construction, at the closing step, in
closing the second through-holes, by inserting a closing tool
including any one shape of a quadrangular pyramid and a
quadrangular pyramid platform into the first through-hole while
allowing the lateral edge of the closing tool to abut against each
of the partition walls that adjoin the second through-holes, the
second through-holes are closed. Thus, the second through-holes can
easily and reliably be closed.
[0018] Further, at the closing step, in closing the first
through-hole, by inserting a closing tool including any one shape
of a quadrangular pyramid and a quadrangular pyramid platform into
each of the second through-holes while allowing the lateral edge of
the closing tool to abut against the partition walls that adjoin
the first through-hole, the first through-hole can be closed.
[0019] According to this construction, at the closing step, in
closing the first through-hole, by inserting a closing tool
including any one shape of a quadrangular pyramid and a
quadrangular pyramid platform into each of the second through-holes
while allowing the lateral edge of the closing tool to abut against
the partition walls that adjoin the first through-hole, the first
through-hole is closed. Thus, the first through-hole can easily and
reliably be closed.
Advantageous Effects of Invention
[0020] The method for producing a honeycomb structure according to
one aspect of the present invention can provide a production method
in which a sealing paste is not needed and which can simply close
the end of the honeycomb structure, and a honeycomb structure
produced by the method.
BRIEF DESCRIPTION OF DRAWINGS
[0021] FIG. 1(a) is a perspective view of a green honeycomb molded
body according to a first embodiment before closing.
[0022] FIG. 1(b) is a partial enlarged view of FIG. 1(a).
[0023] FIG. 2 is a perspective view of a closing apparatus for a
green honeycomb molded body according to a first embodiment.
[0024] FIG. 3 is a partial cross-sectional view of a closing tool
for an inlet side of a green honeycomb molded body according to a
first embodiment.
[0025] FIG. 4 is an enlarged perspective view of a portion A of
FIG. 3.
[0026] FIG. 5 is an enlarged plan view of a portion A of FIG.
3.
[0027] FIG. 6 is a partial cross-sectional view illustrating an
initial state of a closing step on an inlet side of a green
honeycomb molded body according to a first embodiment.
[0028] FIG. 7 is a cross-sectional view taken along line VII-VII of
FIG. 6.
[0029] FIG. 8 is a partial cross-sectional view illustrating a
middle state of a closing step in FIG. 6.
[0030] FIG. 9 is a cross-sectional view taken along line IX-IX of
FIG. 8.
[0031] FIG. 10 is a partial cross-sectional view illustrating a
final state of a closing step in FIG. 6.
[0032] FIG. 11 is a cross-sectional view taken along line XI-XI of
FIG. 10.
[0033] FIG. 12 is a partial cross-sectional view illustrating an
initial state of a closing step on an outlet side of a green
honeycomb molded body according to a first embodiment.
[0034] FIG. 13 is a cross-sectional view taken along line XIII-XIII
of FIG. 12.
[0035] FIG. 14 is a partial cross-sectional view illustrating a
middle state of a closing step in FIG. 12.
[0036] FIG. 15 is a cross-sectional view taken along line XV-XV of
FIG. 14.
[0037] FIG. 16 is a partial cross-sectional view illustrating a
final state of a closing step in FIG. 12.
[0038] FIG. 17 is a cross-sectional view taken on line XVII-XVII of
FIG. 16.
[0039] FIG. 18(a) is a diagram illustrating flow of gas that passes
through conventional closed cells.
[0040] FIG. 18(b) is a diagram illustrating flow of gas that passes
through closed cells according to an embodiment of the present
invention.
[0041] FIG. 19(a) is a perspective view of a green honeycomb molded
body according to a first embodiment before closing.
[0042] FIG. 19(b) is a partial enlarged view of FIG. 19(a).
[0043] FIG. 20 is a cross-sectional view corresponding to a cross
section taken along line VII-VII of FIG. 6 in a closing step on an
inlet side in a second embodiment.
[0044] FIG. 21 is a cross-sectional view corresponding to a cross
section taken along line IX-IX of FIG. 8 in a closing step on an
inlet side according to a second embodiment.
[0045] FIG. 22 is a cross-sectional view corresponding to a cross
section taken along line XI-XI of FIG. 10 in a closing step on an
inlet side according to a second embodiment.
[0046] FIG. 23 is a cross-sectional view corresponding to a cross
section taken along line XIII-XIII of FIG. 12 in a closing step on
an outlet side according to a second embodiment.
[0047] FIG. 24 is a cross-sectional view corresponding to a cross
section taken along line XV-XV of FIG. 14 in a closing step on an
outlet side according to a second embodiment.
[0048] FIG. 25 is a cross-sectional view corresponding to a cross
section taken along line XVII-XVII of FIG. 16 in a closing step on
an outlet side according to a second embodiment.
DESCRIPTION OF EMBODIMENTS
[0049] Embodiments of the present invention will be described in
detail with reference to the drawings.
First Embodiment
Green Honeycomb Molded Body (Octagonal Cells and Quadrangular
Cells)
[0050] First, a green honeycomb molded body that is an object to be
machined in the first embodiment of the present invention will be
described. As illustrated in FIG. 1(a), a green honeycomb molded
body 70 according to this embodiment is, for example, a cylindrical
body that has an upper surface 71a, a lower surface 71b, and a side
surface 71c, and in which a plurality of inlet-side octagonal cells
70Octin that are octagonal through-holes and a plurality of
outlet-side quadrangular cells 70Sout that are quadrangular
through-holes are open in the upper surface 71a and the lower
surface 71b. The inlet-side octagonal cells 70Octin and the
outlet-side quadrangular cells 70Sout extend substantially parallel
from the upper surface 71a to the lower surface 71b along a side
surface 71c. The green honeycomb molded body 70 is an unfired
molded body that, by firing later, becomes a porous ceramic.
Further, the length of the direction in which the inlet-side
octagonal cells 70Octin and the outlet-side quadrangular cells
70Sout in the green honeycomb molded body 70 extend is not
particularly limited but may be, for example, 40 to 400 mm. The
outer diameter of the green honeycomb molded body 70 is also not
particularly limited but may be, for example, 10 to 360 mm.
[0051] As illustrated in FIG. 1(b), in the upper surface 71a or the
lower surface 71b, the inlet-side octagonal cells 70Octin having a
large opening area and the outlet-side quadrangular cells 70Sout
having a smaller opening area than the inlet-side octagonal cells
70Octin are partitioned by partition walls 70W. The inlet-side
octagonal cells 70Octin have an octagonal shape in which the corner
portion of the quadrilateral shape is further cut by a straight
side. Four outlet-side quadrangular cells 70Sout are respectively
adjacent to portions around one inlet-side octagonal cell 70Octin
through four partition walls 70W that partition four sides except
for the corner portion of the inlet-side octagonal cells 70Octin.
Four inlet-side octagonal cells 70Octin are respectively adjacent
to portions around one outlet-side quadrangular cell 70Sout through
four partition walls 70W that partition respective sides of the
outlet-side quadrangular cells 70Sout. The inlet-side octagonal
cells 70Octin may not have a regular octahedral shape, and the
outlet-side quadrangular cells 70Sout may not have a regular square
shape. For example, the inlet-side octagonal cells 70Octin may have
an octagonal shape that is long in one direction, and the
outlet-side quadrangular cells 70Sout may have a rectangular shape.
Further, the inlet-side octagonal cells 70Octin may have an
octagonal shape in which the corner portion of a parallelogram
shape is cut by a straight side, and the outlet-side quadrangular
cells 70Sout may have a parallelogram shape.
[0052] It should be noted that the outer shape of the green
honeycomb molded body 70 is not limited to a cylindrical shape and
may be an elliptical column, an angular column (for example, a
regular polygonal column such as a triangular column, a square
column, a hexagonal column, or an octagonal column; or a triangular
column, a square column, a hexagonal column, or an octagonal column
other than the regular polygonal column) or the like. In this
embodiment, a cylindrical shape of the green honeycomb molded body
70 will be described.
[0053] Such a green honeycomb molded body 70 is produced by
extruding a ceramic composition with an extruder. In this case, in
order to prepare a ceramic composition, a powder of an inorganic
compound source which is a ceramic raw material, an organic binder,
a solvent, and, if necessary, additives to be added are
provided.
[0054] Inorganic compound source powders include powders containing
two or more types of powders selected from the group consisting of
aluminum source powders, magnesium source powders, silicon source
powders, and titanium source powders; or powders containing one or
more types of powders selected from any one of silicon carbide
source powders, silicon nitride source powders, and aluminum
nitride source powders. In order to improve heat resistance and
mechanical strength of products, one or more types of any one of
carbon source powders, zirconium source powders, molybdenum source
powers, and calcium source powders may be added to the inorganic
compound source powder. Including aluminum source powders,
magnesium source powders, titanium source powders, and silicon
source powders can improve heat resistance. Examples of organic
binders include celluloses such as methylcellulose,
carboxylmethylcellulose, hydroxyalkylmethylcellulose, and sodium
carboxylmethylcellulose; alcohols such as polyvinyl alcohol; and
lignin sulfonic acid salts. Additives include, for example, pore
forming agents, lubricating agents and plasticizers, dispersing
agents, and solvents.
[0055] The green honeycomb molded body according to this embodiment
is produced by mixing the prepared raw materials with a kneader or
the like to obtain a raw material mixture, and extruding the raw
material mixture thus obtained through an extruder having an outlet
opening corresponding to the sectional shape of the partition walls
70W.
[0056] (Ultrasonic Closing Machine)
[0057] An ultrasonic closing machine in this embodiment will be
described below. As illustrated in FIG. 2, an ultrasonic closing
machine 300 in this embodiment includes an ultrasonic signal
transmitter 310, an ultrasonic oscillator 320, a horn 330, and a
closing tool 400. As with the above ultrasonic cutter 200, the
ultrasonic signal transmitter 310 transmits electric ultrasonic
signals. The ultrasonic oscillator 320 converts electric ultrasonic
signals supplied from the ultrasonic signal transmitter 310 to
mechanical ultrasonic vibration. The horn 330 amplifies an
amplitude of the ultrasonic vibration supplied from the ultrasonic
oscillator 220. The closing tool 400 is vibrated at a frequency of
about 20 to 40 kHz by the ultrasonic vibration supplied from the
horn 330.
[0058] (Closing Tool)
[0059] The closing tool in this embodiment will be described below.
In this embodiment, closing is carried out in an identical mode at
both end surfaces of the green honeycomb molded body 70 having the
inlet-side octagonal cells 70Octin and the outlet-side quadrangular
cells 70Sout. First, a closing tool for closing an upper surface
71a located on an exhaust gas supply side (inlet side) when the
green honeycomb molded body 70 is applied to a
particulate-matter-removing filter such as a diesel particulate
filter after firing will be described.
[0060] As illustrated in FIG. 3, a closing tool 400 in this
embodiment includes a closing surface 401a for performing closing
of the green honeycomb molded body 70; and a support socket 450 in
which the end of the green honeycomb molded body 70 is fitted. In
the closing surface 401a, a plurality of closing projections 410a
for welding partition walls 70W to each other and closing the
outlet-side quadrangular cells 70Sout are provided by being
arranged at positions corresponding to the inlet-side octagonal
cells 70Octin and inserted respectively into the inlet-side
octagonal cells 70Octin. The support socket 450 is formed of a
cylindrical concave corresponding to the diameter of the green
honeycomb molded body 70 to be closed. An inclined surface 451 is
provided on the inner periphery of the support socket 450 in such a
manner that the inner diameter of the support socket 450 increases
with an increase in distance from the closing surface 401a to
facilitate the insertion of the end of the green honeycomb molded
body 70 into the support socket 450.
[0061] As illustrated in FIGS. 4 and 5 that are enlarged views of a
site corresponding to a portion A in the above-described FIG. 3,
the closing tool 400 in this embodiment includes closing
projections 410c in a closing surface 401c of a closing tool 40
that is identical to that in the first embodiment. The closing
projections 410c include a quadrangular pyramid-shaped base 416 and
a conical tip 412. The quadrangular pyramid-shaped base 416 is
located at a base of the closing projections 410c and is projected
from the closing surface 401c. The quadrangular pyramid-shaped base
416 has a square cone platform shape in which a quadrangular
pyramid reduced similarly from a quadrangular pyramid having a
larger apex angle than the conical tip 412 is removed. The conical
tip 412 is located at a position that is a tip of the closing
projections 410c and above the quadrangular pyramid-shaped base
416. The conical tip 412 has a conical shape having a bottom
surface having a size corresponding to the upper surface of the
quadrangular pyramid-shaped base 416. The apex angle of the conical
tip 412 is smaller than the apex angle defined by lateral edges of
the square cone platform of the quadrangular pyramid-shaped base
416.
[0062] The quadrangular pyramid-shaped base 416 includes a
quadrangular pyramid side surface 417 that is a side surface of the
square cone platform; and a roundness chamfering lateral edge 415
on the lateral edge of the square cone platform. In the roundness
chamfering lateral edge 415, roundness chamfering has been
conducted at a prescribed curvature for each lateral edge of the
square cone platform. Further, the valley between the quadrangular
pyramid-shaped bases 416 in adjacent closing projections 410c
includes a roundness chamfering valley 414 that is a concave formed
by roundness chamfering at a prescribed curvature.
[0063] As illustrated in FIG. 5, in each of the closing projections
410c, apexes of conical tips 412 are arranged respectively at
positions corresponding to the plurality of inlet-side octagonal
cells 70Octin in the green honeycomb molded body 70. Further, in
each of the closing projections 410c, the roundness chamfering
lateral edge 415 of the quadrangular pyramid-shaped base 416 is
arranged in a direction that abuts against the partition wall 70W.
The size of each of the quadrangular pyramid-shaped bases 416 is a
size such that a length that the roundness chamfering lateral edge
415 projects on the closing surface 401c from just above the
closing surface 401c corresponds to a length between the center of
the inlet-side octagonal cells 70Octin and the center of the
outlet-side quadrangular cells 70Sout in the green honeycomb molded
body 70.
[0064] It should be noted that when the green honeycomb molded body
70 is applied to a particulate-matter-removing filter such as a
diesel particulate filter after firing, as with the upper surface
71a, a closing tool 400 that has a closing surface 401c with
closing projections 410c arranged at positions corresponding to the
outlet-side quadrangular cells 70Sout is used as the closing tool
400 for closing the lower surface 71b functioning as an exhaust gas
discharge side (an outlet side).
[0065] (Closing Step)
[0066] The step of closing the green honeycomb molded body 70 in
this embodiment will be described below. First, in the case where
the green honeycomb molded body 70 is applied to a
particulate-matter-removing filter such as a diesel particulate
filter after firing, the step of closing the upper surface 71a
functioning as an exhaust gas supply side (an inlet side) will be
described.
[0067] As illustrated in FIG. 6, the end on the upper surface 71a
side of the green honeycomb molded body 70 is inserted into the
support socket 450 in the closing tool 400 in the ultrasonic
closing machine 300. The closing tool 400 is vibrated by ultrasonic
vibration from the horn 330. As illustrated in FIG. 7, the tip of
the closing projections 410c in the closing surface 401c is
inserted into the inlet-side octagonal cells 70Octin. The conical
tip 412 of the closing projections 410c is inserted into the
inlet-side octagonal cells 70Octin.
[0068] As illustrated in FIG. 8, when the closing projections 410c
are further inserted into the inlet-side octagonal cells 70Octin,
as illustrated in FIG. 9, the quadrangular pyramid-shaped base 416
of the closing projections 410c is inserted into the inlet-side
octagonal cells 70Octin. The roundness chamfering lateral edges 415
in the quadrangular pyramid-shaped base 416 each abut against the
partition walls 70W. Since the closing projections 410c are
vibrated by ultrasonic vibration, the partition walls 70W are
liquefied and pressed so as to close the outlet-side quadrangular
cells 70Sout into which the closing projections 410c, that are
located at the center of four inlet-side octagonal cells 70Octin
into which the closing projections 410c have respectively been
inserted, have not been inserted.
[0069] As illustrated in FIG. 10, when the closing projections 410c
are further inserted into the inlet-side octagonal cells 70Octin,
as illustrated in FIG. 11, the partition walls 70W that have been
pressed from four directions while being liquefied by the roundness
chamfering lateral edge 415 and the quadrangular pyramid side
surface 417 in the quadrangular pyramid-shaped base 416 are
integrally welded to each other. The end of the welded partition
walls 70W is abutted against the roundness chamfering valley 414 in
the closing surface 401c, and a round partition wall joined end 73
is formed in such a state that roundness chamfering corresponding
to the shape of the roundness chamfering valley 414 has been
conducted, thereby completing closing. Thus, in the upper surface
71a functioning as the exhaust gas supply side (inlet side), one
outlet-side quadrangular cell 70Sout that is surrounded by four
inlet-side octagonal cells 70Octin respectively adjoining the
periphery of one outlet-side quadrangular cell 70Sout with the
partition walls 70W provided between is closed.
[0070] On the other hand, when the green honeycomb molded body 70
is applied to a particulate-matter-removing filter such as a diesel
particulate filter after firing, for the step of closing the lower
surface 71b functioning as the exhaust gas discharge side (outlet
side), as illustrated in FIG. 12, the end on the lower surface 71b
side of the green honeycomb molded body 70 is inserted into the
support socket 450 in the closing tool 400 in the ultrasonic
closing machine 300. The closing tool 400 is vibrated by ultrasonic
vibration from the horn 330. The tip of the closing projections
410c in the closing surface 401c is inserted into the outlet-side
quadrangular cells 70S out. As illustrated in FIG. 13, the conical
tip 412 in the closing projections 410c is inserted into the
outlet-side quadrangular cells 70Sout.
[0071] As illustrated in FIG. 14, when the closing projections 410c
are further inserted into the outlet-side quadrangular cells
70Sout, the quadrangular pyramid-shaped base 416 in the closing
projections 410c is inserted into the outlet-side quadrangular
cells 70Sout, as illustrated in FIG. 15. Each of the roundness
chamfering lateral edges 415 in the quadrangular pyramid-shaped
base 416 is abutted against the partition walls 70W. Since the
closing projections 410c are vibrated by ultrasonic vibration, the
partition walls 70W are liquefied and each is pressed so as to
close the inlet-side octagonal cells 70Octin into which the closing
projections 410c have not been inserted and that are located at the
center of the four outlet-side quadrangular cells 70Sout into which
the closing projections 410c have been inserted.
[0072] As illustrated in FIG. 16, when the closing projections 410c
are further inserted into the outlet-side quadrangular cells
70Sout, as illustrated in FIG. 17, the partition walls 70W that
have been pressed from four directions while being liquefied by the
roundness chamfering lateral edge 415 and the quadrangular pyramid
side surface 417 in the quadrangular pyramid-shaped base 416 are
integrally welded to each other. The end of the welded partition
walls 70W is abutted against the roundness chamfering valley 414 in
the closing surface 401c, and a round partition wall joined end 73
is formed in such a state that roundness chamfering corresponding
to the shape of the roundness chamfering valley 414 has been
conducted, thereby completing closing. Thus, in the lower surface
71b functioning as the exhaust gas discharge side (outlet side),
one inlet-side octagonal cell 70Octin that is surrounded by four
outlet-side quadrangular cells 70Sout respectively adjoining the
periphery of one inlet-side octagonal cell 70Octin with the
partition walls 70W provided between is closed.
[0073] In this embodiment, in the method for producing a honeycomb
structure, a plurality of inlet-side octagonal cells 70Octin and a
plurality of outlet-side quadrangular cells 70Sout that have been
mutually partitioned by partition walls 70W are open in an upper
surface 71a and a lower surface 71b of a columnar body. The
inlet-side octagonal cells 70Octin or the outlet-side quadrangular
cells 70Sout are closed by joining together the partition walls 70W
in the green honeycomb molded body 70, that become a honeycomb
structure by firing, at the upper surface 71a and the lower surface
71b. Thereby, since the cells are closed by joining the partition
walls (cell walls) 70W together, there is no need to use closing
pastes such as in conventional methods. Further, since the cells
are closed by welding the cell walls together, when the honeycomb
structure is used in a particulate-matter-removing filter such as a
diesel particulate filter, the inlet and the outlet of exhaust gas
flow passages in the end surface can be made larger than an opening
area of the through-holes, whereby turbulence of the flow of the
exhaust gas at the end surface on the exhaust gas supply side can
be reduced and pressure loss can be reduced. As illustrated in FIG.
18(a), when the outlet-side quadrangular cells 70Sout are closed
with a conventional closing material 70P, there is a drawback that
air resistance is large at the upper surface 71a functioning as the
exhaust gas supply side (inlet side). On the other hand, as
illustrated in FIG. 18(b), when the outlet-side quadrangular cells
70Sout are closed by the production method in this embodiment,
since the inlet of the gas flow passage in the upper surface 71a is
large and the end of the closed partition walls 70W is tapered, the
air resistance can be reduced to a very high extent.
[0074] The green honeycomb molded body 70 with a part of
through-holes to be closed has, in the upper surface 71a or the
lower surface 71b, one inlet-side octagonal cell 70Octin and four
outlet-side quadrangular cells 70Sout that have a smaller opening
area than the inlet-side octagonal cell 70Octin adjoining around
the one inlet-side octagonal cell 70Octin through the partition
walls 70W. Accordingly, for example, when the honeycomb structure
is applied to a particulate-matter-removing filter such as a diesel
particulate filter, in the particulate-matter-removing filter, when
the inlet-side octagonal cells 70Octin having a large opening area
are opened while closing the outlet-side quadrangular cells 70Sout
having a small opening area on the inlet side, and when the
outlet-side quadrangular cells 70Sout having a small opening area
are opened while closing the inlet-side octagonal cells 70Octin
having a large opening area on the outlet side, the inlet side
becomes wide and the pressure loss in such a state that soot is
deposited can be reduced.
[0075] Further, the through-holes having a large opening area are
inlet-side octagonal cells 70Octin and the through-holes that
adjoin around the inlet-side octagonal cells 70Octin and have a
small opening area are outlet-side quadrangular cells 70Sout.
Therefore, when the outlet-side quadrangular cell 70Sout adjoins
every other side of the inlet-side octagonal cell 70Octin,
through-holes having a different size can be arranged in the upper
surface 71a or the lower surface 71b.
[0076] Further, in the upper surface 71a, the outlet-side
quadrangular cells 70Sout are closed, and, in the lower surface
71b, the inlet-side octagonal cells 70Octin are closed. Thus, for
example, when the honeycomb structure is applied to a
particulate-matter-removing filter such as a diesel particulate
filter, in the particulate-matter-removing filter, when the
inlet-side octagonal cells 70Octin having a large opening area are
opened while closing the outlet-side quadrangular cells 70S out
having a small opening area on the inlet side, and when the
outlet-side quadrangular cells 70Sout having a small opening area
are opened while closing the inlet-side octagonal cells 70Octin
having a large opening area on the outlet side, the inlet side
becomes wide and the pressure loss in such a state that soot is
deposited can be reduced.
[0077] When closing projections 410c in the closing tool 400 are
inserted into the plurality of inlet-side octagonal cells 70Octin
or outlet-side quadrangular cells 70Sout in the green honeycomb
molded body 70, the partition walls 70W are joined together at the
upper surface 71a or the lower surface 71b and the cells are
closed. Thus, the closing of the cells can very easily be carried
out.
[0078] Further, in the closing of the outlet-side quadrangular
cells 70Sout, the outlet-side quadrangular cells 70Sout are closed
by inserting closing projections 410c in the closing tool 400
including any shape of a quadrangular pyramid and a quadrangular
pyramid platform into the inlet-side octagonal cells 70Octin while
allowing the roundness chamfering lateral edge 415 to abut against
each of the partition walls 70W that adjoin the roundness
chamfering lateral edge 415. Thus, the outlet-side quadrangular
cells 70Sout can be closed easily and reliably.
[0079] Further, in the closing of the inlet-side octagonal cells
70Octin, the inlet-side octagonal cells 70Octin are closed by
inserting closing projections 410c in the closing tool 400
including any shape of a quadrangular pyramid and a quadrangular
pyramid platform into through-holes, respectively, in the
outlet-side quadrangular cells 70Sout while allowing the roundness
chamfering lateral edge 415 of the closing projections 410c to abut
against the partition walls 70W adjacent to the inlet-side
octagonal cells 70Octin. Thus, the inlet-side octagonal cells
70Octin can be closed easily and reliably.
Second Embodiment
Green Honeycomb Molded Body (Rounded Quadrangular Cells and
Quadrangular Cells)
[0080] First, a green honeycomb molded body that is an object to be
machined in the second embodiment of the present invention will be
described. As illustrated in FIG. 19(a), a green honeycomb molded
body 70 in this embodiment is, for example, a cylindrical body that
has an upper surface 71a, a lower surface 71b, and a side surface
71c and in which a plurality of inlet-side rounded quadrangular
cells 70SRin that are rounded quadrangular through-holes with the
corner of the quadrangle being rounded, and outlet-side
quadrangular cells 70Sout that are quadrangular through-holes that
are the same as those in the first embodiment are open in the upper
surface 71a and the lower surface 71b. The inlet-side rounded
quadrangular cells 70SRin and the outlet-side quadrangular cells
70Sout extend substantially parallel from the upper surface 71a to
the lower surface 71b along the side surface 71c. As with the
above-described first embodiment, the green honeycomb molded body
70 is an unfired molded body that, by firing later, becomes a
porous ceramic and is identical in material and production method
to that in the first embodiment except for the inlet-side rounded
quadrangular cells 70SRin. Further, the length of the direction in
which the inlet-side rounded quadrangular cells 70SRin and the
outlet-side quadrangular cells 70Sout in the green honeycomb molded
body 70 extend is not particularly limited but may be, for example,
40 to 400 mm.
[0081] As illustrated in FIG. 19(b), in the upper surface 71a or
the lower surface 71b, inlet-side rounded quadrangular cells 70SRin
having a large opening area and outlet-side quadrangular cells
70Sout having a smaller opening area than the inlet-side rounded
quadrangular cells 70SRin are partitioned by partition walls 70W.
The inlet-side rounded quadrangular cells 70SRin have a rounded
quadrangular shape in which the corner of the quadrangle has been
roundly chamfered. Four outlet-side quadrangular cells 70Sout
adjoin around one inlet-side rounded quadrangular cell 70SRin
through respective four partition walls 70W that partition the four
sides of the inlet-side rounded quadrangular cell 70SRin. Four
inlet-side rounded quadrangular cells 70SRin adjoin around one
outlet-side quadrangular cell 70Sout through respective four
partition walls 70W that partition each side of the outlet-side
quadrangular cells 70Sout. It should be noted that the inlet-side
rounded quadrangular cells 70SRin may not be one in which the
corner of a square has been rounded. For example, the inlet-side
rounded quadrangular cells 70SRin may have a round quadrangular
shape that is elongate in one direction. Alternatively, the
inlet-side rounded quadrangular cells 70SRin may have a round
quadrangular shape in which the corner of a parallelogram has been
rounded.
[0082] (Closing Step)
[0083] The step of closing the green honeycomb molded body 70 in
this embodiment will be described below. In this embodiment, the
inlet-side rounded quadrangular cells 70SRin and the outlet-side
quadrangular cells 70Sout are closed using a closing tool 400 that
is the same as that in the above-described first embodiment. First,
the step of closing the upper surface 71a functioning as an exhaust
gas supply side (an inlet side) in the case where the green
honeycomb molded body 70 is applied to a
particulate-matter-removing filter such as a diesel particulate
filter after firing will be described.
[0084] As illustrated in FIG. 6, the end on the upper surface 71a
side of the green honeycomb molded body 70 is inserted into the
support socket 450 in the closing tool 400 in the ultrasonic
closing machine 300. The closing tool 400 is vibrated by ultrasonic
vibration from the horn 330. As illustrated in FIG. 20, the tip of
the closing projections 410c in the closing surface 401c is
inserted into the inlet-side rounded quadrangular cells 70SRin. The
conical tip 412 of the closing projections 410c is inserted into
the inlet-side rounded quadrangular cells 70SRin.
[0085] As illustrated in FIG. 8, when the closing projections 410c
are further inserted into the inlet-side rounded quadrangular cells
70SRin, as illustrated in FIG. 21, the quadrangular pyramid-shaped
base 416 in the closing projections 410c are inserted into the
inlet-side rounded quadrangular cells 70SRin. The roundness
chamfering lateral edges 415 in the quadrangular pyramid-shaped
base 416 each abut against the partition walls 70W. Since the
closing projections 410c are vibrated by ultrasonic vibration, the
partition walls 70W are liquefied and pressed so as to close the
outlet-side quadrangular cells 70Sout into which the closing
projections 410c have not been inserted that are located at the
center of four inlet-side rounded quadrangular cells 70SRin into
which the closing projections 410c have respectively been
inserted.
[0086] As illustrated in FIG. 10, when the closing projections 410c
are further inserted into the inlet-side rounded quadrangular cells
70SRin, as illustrated in FIG. 22, the partition walls 70W that
have been pressed from four directions while being liquefied by the
roundness chamfering lateral edge 415 and the quadrangular pyramid
side surface 417 in the quadrangular pyramid-shaped base 416 are
integrally welded to each other. The end of the welded partition
walls 70W is abutted against the roundness chamfering valley 414 in
the closing surface 401c, and a round partition wall joined end 73
is formed in such a state that roundness chamfering corresponding
to the shape of the roundness chamfering valley 414 has been
conducted, thereby completing closing. Thus, in the upper surface
71a functioning as the exhaust supply side (inlet side), one
outlet-side quadrangular cell 70Sout that is surrounded by four
inlet-side rounded quadrangular cells 70SRin respectively adjoining
the periphery of one outlet-side quadrangular cell 70Sout with the
partition walls 70W provided between is closed.
[0087] On the other hand, when the green honeycomb molded body 70
is applied to a particulate-matter-removing filter such as a diesel
particulate filter after firing, for the step of closing the lower
surface 71b functioning as the exhaust gas discharge side (outlet
side), as illustrated in FIG. 12, the end on the lower surface 71b
side of the green honeycomb molded body 70 is inserted into the
support socket 450 in the closing tool 400 in the ultrasonic
closing machine 300. The closing tool 400 is vibrated by ultrasonic
vibration from the horn 330. The tip of the closing projections
410c in the closing surface 401c are inserted into the outlet-side
quadrangular cells 70Sout. As illustrated in FIG. 23, the conical
tip 412 of the closing projections 410c is inserted into the
outlet-side quadrangular cells 70Sout.
[0088] As illustrated in FIG. 14, when the closing projections 410c
are further inserted into the outlet-side quadrangular cells
70Sout, the quadrangular pyramid-shaped base 416 in the closing
projections 410c is inserted into the outlet-side quadrangular
cells 70Sout, as illustrated in FIG. 24. Each of the roundness
chamfering lateral edges 415 in the quadrangular pyramid-shaped
base 416 is abutted against the partition walls 70W. Since the
closing projections 410c are vibrated by ultrasonic vibration, the
partition walls 70W are liquefied and each are pressed so as to
close the inlet-side rounded quadrangular cells 70SRin into which
the closing projections 410c have not been inserted and that are
located at the center of the four outlet-side quadrangular cells
70Sout into which the closing projections 410c have been
inserted.
[0089] As illustrated in FIG. 16, when the closing projections 410c
are further inserted into the inlet-side octagonal cells 70Octin,
as illustrated in FIG. 25, the partition walls 70W that have been
pressed from four directions while being liquefied by the roundness
chamfering lateral edge 415 and the quadrangular pyramid side
surface 417 in the quadrangular pyramid-shaped base 416 are
integrally welded to each other. The end of the welded partition
walls 70W is abutted against the roundness chamfering valley 414 in
the closing surface 401c, and a round partition wall joined end 73
is formed in such a state that roundness chamfering corresponding
to the shape of the roundness chamfering valley 414 has been
conducted, thereby completing closing. Thus, in the lower surface
71b functioning as the exhaust gas discharge side (outlet side),
one inlet-side rounded quadrangular cell 70SRin that is surrounded
by four outlet-side quadrangular cells 70Sout respectively
adjoining the periphery of the lower surface 17b with the partition
walls 70W provided between is closed.
[0090] In this embodiment, the through-holes having a large opening
area are inlet-side rounded quadrangular cells 70SRin and the
through-holes that adjoin around the inlet-side rounded
quadrangular cells 70SRin and have a small opening area are
outlet-side quadrangular cells 70Sout. Therefore, when the
outlet-side quadrangular cell 70Sout adjoins every other side of
the inlet-side rounded quadrangular cells 70SRin, through-holes
having a different size can be arranged in the upper surface 71a or
the lower surface 71b.
[0091] It should be noted that the present invention is not limited
to the above embodiments, and various modifications are possible.
For example, in the above embodiments, the closed green honeycomb
molded body 70 has been closed by welding the partition walls 70W
together through the application of ultrasonic waves. However, the
closed green honeycomb molded body 70 is not limited to this
embodiment. For example, the closed green honeycomb molded body 70
includes a closed green honeycomb molded body 70 that has been
closed by contact bonding between partition walls 70W without the
application of ultrasonic waves. Further, the closed green
honeycomb molded body 70 includes a closed green honeycomb molded
body 70 that has been closed by contact bonding between partition
walls 70W through the application of vibration at a lower frequency
than ultrasonic waves, for example, at 1 kHz or less.
INDUSTRIAL APPLICABILITY
[0092] The method for producing a honeycomb structure according to
one aspect of the present invention can provide a production method
in which a sealing paste is not needed and which can simply close
the end of the honeycomb structure, and a honeycomb structure
produced by the method.
REFERENCE SIGNS LIST
[0093] 70 . . . green honeycomb molded body [0094] 71a . . . upper
surface [0095] 71b . . . lower surface [0096] 71c . . . side
surface [0097] 70Octin . . . inlet-side octagonal cells [0098]
70Sout . . . outlet-side quadrangular cells [0099] 70SRin . . .
inlet-side rounded quadrangular cells [0100] 70W . . . partition
walls [0101] 73 . . . round partition wall joined end [0102] 300 .
. . ultrasonic closing machine [0103] 310 . . . ultrasonic signal
transmitter [0104] 320 . . . ultrasonic oscillator [0105] 330 . . .
horn [0106] 400 . . . closing tool [0107] 401c . . . closing
surface [0108] 410c . . . closing projections [0109] 412 . . .
conical tip [0110] 414 . . . roundness chamfering valley [0111] 415
. . . roundness chamfering lateral edge [0112] 416 . . .
quadrangular pyramid-shaped base [0113] 417 . . . quadrangular
pyramid side surface [0114] 450 . . . support socket [0115] 451 . .
. inclined surface
* * * * *