Patent Application
20160271831
An aspect of the present invention relates to a method for producing honeycomb structures and a closing tool for green honeycomb molded bodies, and also relates to a method for producing honeycomb structures in which a green honeycomb molded body is fired to produce a honeycomb structure, and a closing tool for green honeycomb molded bodies.
For example, ceramic honeycomb structures having a plurality of through-holes of a cross-sectional 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 process 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 the end surface. A honeycomb structure is produced by firing a green honeycomb molded body with closed through-holes. Patent Literature 1 discloses a method for producing such honeycomb structures. In Patent Literature 1, projections in a closing tool having a plurality of quadrangular pyramid-shaped projections are inserted into a part of the through-holes in the green honeycomb molded body to gather together ends of partition walls that partition the through-holes and to connect the ends of these partition walls, thereby closing the through-holes.
PTL 1: Japanese Unexamined Patent Publication No. H8-508199
However, in the method in the above Patent Literature 1, when the number of through-holes into which the closing tool is inserted increases, there is a drawback that removing the closing tool after closing the through-holes becomes difficult. On the other hand, a method in which the closing tool is inserted a plurality of times into a small number of through-holes at a time has a drawback that the number of through-holes that can be closed at the same time is reduced, leading to a lowered closing efficiency.
In the technical field, a method for producing a honeycomb structure and a closing tool for a green honeycomb molded body that can produce a honeycomb structure more efficiently and easily have been desired.
One aspect of the present invention is a method for producing a honeycomb structure comprising a plurality of holes that open in an end surface of a columnar body and are mutually partitioned by partition walls, the method comprising a closing step of closing through-holes by inserting a closing tool into a part of a plurality of the through-holes in a green honeycomb molded body comprising the plurality of through-holes that open in the end surface of the columnar body and are mutually partitioned by partition walls to join the partition walls together; and a removal step of removing the closing tool inserted into a part of the through-holes in the closing step from the through-holes, wherein, at the closing step, the integrated closing tool is inserted into the plurality of the through-holes simultaneously, and, at the removal step, a part of the integrated closing tool is separated and the separated closing tool is removed from a part of the through-holes into which the closing tool was simultaneously inserted at the closing step.
According to this construction, in a method for producing a honeycomb structure comprising a plurality of holes that open in an end surface of a columnar body and are mutually partitioned by partition walls, the method comprises a closing step of closing through-holes by inserting a closing tool into a part of a plurality of the through-holes in a green honeycomb molded body comprising the plurality of through-holes that open in the end surface of the columnar body and are mutually partitioned by partition walls to join the partition walls together; and a removal step of removing the closing tool inserted into a part of the through-holes in the closing step from the through-holes. At the closing step, the integrated closing tool is inserted into the plurality of the through-holes simultaneously, and, thus, a plurality of through-holes can be closed in a simultaneous and efficient manner. On the other hand, at the removal step, a part of the integrated closing tool is separated and the separated closing tool is removed from a part of the through-holes into which the closing tool was simultaneously inserted at the closing step. Thereby, the removal of the closing tool from the through-holes is facilitated. Therefore, the production of honeycomb structures can be carried out more efficiently and easily.
In this case, at the closing step, by inserting a closing tool into a part of through-holes, the partition walls can be joined together so that the partition walls are parallel to each other over a prescribed length from the end surface.
According to this method, at the closing step, by inserting a closing tool into a part of through-holes, the partition walls can be joined together so that the partition walls are parallel to each other over a prescribed length from the end surface. Accordingly, when the honeycomb structure is used as a particulate-matter-removing filter such as a diesel particulate filter, the air resistance in the junction between the partition walls is reduced and pressure loss can be reduced. Further, chipping or the like at the joined end can be made less likely to occur. When the joining is performed so that the partition walls are parallel to each other over a prescribed length from the end surface, the area of contact between the partition walls and the closing tool increases and it is difficult to remove the closing tool from the through-holes. However, in this construction, a part of the integrated closing tool is separated and the separated closing tool is removed from a part of the through-holes into which the closing tool was simultaneously inserted. Therefore, even when the area of contact between the partition walls and the closing tool has become large, the closing tool can easily be removed from the through-holes.
Further, another aspect of the present invention is a closing tool for a green honeycomb molded body comprising a plurality of through-holes that open in an end surface of a columnar body and are mutually partitioned by partition walls, the closing tool comprising: a base; and a plurality of closing projections that are arranged at positions corresponding to a part of the plurality of through-holes in the base and are respectively inserted into a part of the plurality of through-holes to join the partition walls together, thereby closing the through-holes, wherein the base has split pieces with a part of the plurality of closing projections arranged therein, and the split pieces are integratable with and separable from the base.
A method for producing a honeycomb structure according to one aspect of the present invention and a closing tool for a green honeycomb molded body can produce a honeycomb structure more efficiently and easily.
Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
(Green Honeycomb Molded Body)
First, a green honeycomb molded body that is an object to be machined in the embodiment of the present invention will be described. As illustrated in
The hexagonal cells 70h are each partitioned by partition walls 70W that extend substantially parallel to a central axis of the green honeycomb molded body 70. The thickness of the partition walls 70W may be not more than 0.8 mm, not more than 0.5 mm, and not less than 0.1 mm. 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. Further, in this embodiment, a green honeycomb molded body 70 including hexagonal cells 70h that are regular hexagonal through-holes will be given as an example. However, green honeycomb molded bodies 70 including cells that are through-holes that have hexagonal shapes other than a regular hexagonal shape or hexagonal shapes having a different size may also be used.
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 prepared.
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 any one of one or more types of powders selected from 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 powders. 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.
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.
(Closing Tool)
The closing tool in this embodiment will be described below. In this embodiment, when a green honeycomb molded body 70 is applied to a particulate-matter-removing filter such as a diesel particulate filter after firing, a closing tool used in the upper surface 71a functioning as an exhaust gas supply side (an inlet side) and a closing tool used in the lower surface 71b functioning as an exhaust gas discharge side (an outlet side) have different closing projections. First, the closing tool for closing the upper surface 71a functioning as the exhaust gas supply side (inlet side) will be described.
As illustrated in
The base 150 is split at a separating line 165 into a plurality of tool separated pieces 161. As will be described later, the plurality of tool separated pieces 161 constituting the base 150 are each configured to be integratable and separable while supporting the closing projections 110a. A surface of the tool separated pieces 161 opposite to the closing surface 101 has a tool separated piece lever 170 that is a cylindrical metal rod.
As illustrated in
The triangular prismatic base 111 includes a triangular prismatic side surface 113 that is a side surface of a triangular prism, and a round chamfering lateral edge 115 that is a lateral edge of a triangular prism. In the round chamfering lateral edge 115, each lateral edge of the triangular prism has been subjected to round chamfering at a prescribed curvature. The distance between the triangular prismatic side surfaces 113 in closing projections 110a that adjoin each other is at least not less than or at least not less than twice the distance from the closing surface 101 to the upper end of the triangular prismatic side surface 113.
As illustrated in
As illustrated in
On the other hand, closing projections 110b arranged on the closing surface 101 for closing of the lower surface 71b functioning as an exhaust gas discharge side (an outlet 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. As illustrated in
As illustrated in
Accordingly, in the upper surface 71a, the closing projections 110a are inserted into six hexagonal cells 70h that each adjoin around one hexagonal cell 70h as a center, and, in the lower surface 71b, the closing projections 110b are inserted into one hexagonal cell 70h that is surrounded by six adjoining hexagonal cells 70h into which closing projections 110a are inserted in the upper surface 71a thereof The size of each of the closing projections 110b is made so that the radius of the bottom surface in the closing projections 110b becomes a length corresponding to a length between opposite sides of the hexagonal cell 70h in the green honeycomb molded body 70.
(Closing Step)
The step of closing the green honeycomb molded body 70 in this embodiment will be described below. First, when 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.
As illustrated in
In closing the upper surface 71a, as illustrated in
As illustrated in
It should be noted that when the triangular prismatic side surface 113 in the triangular prismatic base 111 of the closing tool 100 is in a substantially plane form rather than a rounded form, as illustrated in
On the other hand, 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, in the step of closing the lower surface 71b functioning as an exhaust gas supply side (an inlet side), as described later, after the removal of the closing tool 100 from the green honeycomb molded body 70, closing is carried out in the same manner as described above using the closing tool 100 including closing projections 110b in the closing surface 101.
In closing the lower surface 71b, as shown in
As illustrated in
Thus, when the closing of the hexagonal cells 70h is completed, as illustrated in
Thus, after the completion of the closing at the upper surface 71a and the lower surface 71b, a firing step is carried out to produce a honeycomb structure having the same shape as the green honeycomb molded body 70 after the closing.
In this embodiment, in the method for producing a honeycomb structure, a closing tool 100 is inserted into a part of a plurality of hexagonal cells 70h in a green honeycomb molded body 70 in which a plurality of hexagonal cells 70h mutually partitioned by partition walls 70W are open in an upper surface 71a and a lower surface 71b in a columnar body and that, by firing, becomes a honeycomb structure, thereby joining the partition walls 70W together and closing hexagonal cells 70h, and the closing tool inserted into a part of the hexagonal cells 70h is removed from the through-holes. Since the integrated closing tool 100 is simultaneously inserted into a plurality of hexagonal cells 70h, the plurality of hexagonal cells 70h can be closed simultaneously and efficiently. On the other hand, a part of the integrated closing tool 100 is separated, and the separated tool separated pieces 161 are removed from a part of the hexagonal cells 70h into which the closing tool 100 has been inserted simultaneously. Thus, the closing tool 100 can easily be removed from the hexagonal cells 70h. Therefore, the honeycomb structure can be produced more efficiently and easily.
Further, in this embodiment, by inserting the closing tool 100 into a part of the hexagonal cells 70h, joining is made so that a partition wall extended junction 75 in which the partition walls 70W are parallel to each other over a prescribed length from the upper surface 71a or the lower surface 71b is formed. Therefore, when the honeycomb structure is applied to a particulate-matter-removing filter such as a diesel particulate filter, the air resistance in the junction between the partition walls 70W is reduced and pressure loss can be reduced. Further, chipping or the like at the joined end can be made less likely to occur. When the joining is made so that the partition walls 70W become parallel to each other over a prescribed length from the upper surface 71a and the lower surface 71b, the area of contact between the partition walls 70W and the closing tool 100 is increased and, thus, the adhesion force is increased, making it difficult to remove the closing tool 100 from the hexagonal cells 70h. Further, by removing the closing tool first from portions having a low adhesion force, the shape of the honeycomb is likely to be broken. In this construction, however, a part of the integrated closing tool 100 is separated and the separated closing tool 100 is removed from a part of the hexagonal cells 70h into which the closing tool 100 has been inserted simultaneously. Therefore, even when the area of contact between the partition walls 70W and the closing tool 100 is large, the closing tool 100 can easily be removed from the hexagonal cells 70h.
It should be noted that the present invention is not limited to the above embodiment, and various modifications are possible. For example, in the above embodiment, in the closed green honeycomb molded body 70, the partition walls 70W have been closed by being contact-bonded to each other. Embodiments of the present invention are not limited to this embodiment. For example, the closed green honeycomb molded body 70 includes a green honeycomb molded body 70 in which closing is carried out by welding the partition walls 70W together through the application of ultrasonic waves. Further, the closed green honeycomb molded body 70 includes a green honeycomb molded body 70 in which the partition walls 70W are closed by being contact-bonded to each other by the application of vibration at a lower frequency than ultrasonic waves, for example, 1 kHz or less.
Further, in the above embodiment, the through-holes are described as hexagonal. However, the cell shape of the through-holes is not limited to a hexagonal shape, and other polygonal shapes (for example, quadrangular shapes or octagonal shapes), or a combination thereof is also possible. Further, for the closing tool, polygonal pyramid shapes or polygonal pyramid platform shapes are also possible according to the cell shape. Further, the shape of the tool on the inlet side and the shape of the tool on the outlet side may be different or the same.
According to the method for producing a honeycomb structure and the closing tool for the green honeycomb molded body according to one aspect of the present invention, a honeycomb structure can be produced more efficiently and easily.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2013-136557 | Jun 2013 | JP | national |
This Application is a continuation of application Ser. No. 14/392,137, filed Dec. 23, 2015, which is a national phase application based on PCT/JP2014/064505, filed May 30, 2014, which claims the priority of Japanese patent Application No. 2013-13657, filed June 28, 2013, the content of each application being incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 14392137 | Dec 2015 | US |
| Child | 15095781 | US |
