JP2008155594A - Manufacturing method of honeycomb structure and mold for molding skinless honeycomb molded article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for easily manufacturing honeycomb structure with high dimensional precision, and to provide a mold for molding a skinless honeycomb molded article. <P>SOLUTION: The manufacturing method of the honeycomb structure includes an extrusion molding step for obtaining the skinless honeycomb structure, the drying step, the skin forming step and the heat treatment step. In the extrusion molding step, a mold body 4 and a guide ring 5 are provided. The mold body 4 has feeding holes 411 which are formed on a hole molding surface 41 for feeding material, and polygonal grid-like slit grooves 421 which are formed on a groove molding surface 42 so as to communicate with the feeding holes 411 in order to mold a material into honeycomb shapes. The guide ring 5 is provided so as to butt against the groove molding surface 42 in order to regulate an outer diameter of the skinless honeycomb molded article. The feeding holes 411 are formed inside a region of the minimum diameter of the guide ring 5 and they are closed for preventing the material from penetrating. The guide ring 5 uses the mold which has the inner circumferential surface 51 having an inclined surface of 100°±5° with respect to the groove molding surface 42. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a honeycomb structure and a mold for forming a skinless honeycomb formed body.

Honeycomb structures are used as catalyst carriers and filters in exhaust gas purification apparatuses for internal combustion engines.
The honeycomb structure has a large number of cells with partition walls arranged in a honeycomb shape. Such a honeycomb structure can be obtained by extruding a ceramic raw material to form a honeycomb formed body, and cutting, drying, and firing the honeycomb formed body.

  Conventionally, in manufacturing the honeycomb formed body, first, a honeycomb formed body having a shape to be finally obtained is formed by extrusion. However, in this extrusion molding, it is difficult to form a honeycomb molded body having a complicated shape. Further, even if a honeycomb formed body having a desired shape is obtained, deformation / cracking or the like may occur in the subsequent steps, which may reduce the dimensional accuracy.

Therefore, as a method for finally obtaining a desired shape with high dimensional accuracy, for example, in Patent Document 1, after extruding a molded body having an outer skin, drying, removing the peripheral portion, performing firing, Thereafter, a ceramic honeycomb structure having an outer skin formed on the outer peripheral surface is disclosed.
However, since machining is performed to remove the outer periphery before forming the outer skin, there are problems such as damage to cells opened to the outside during processing, and problems such as deformation and cracking in subsequent processes, and removal processing. There is a problem in that the cost increases by doing so.
Therefore, there is a demand for a method for manufacturing a honeycomb structure that can easily manufacture a honeycomb structure with high dimensional accuracy.

JP 2004-148791 A

  The present invention has been made in view of such conventional problems, and is a method for manufacturing a honeycomb structure capable of easily manufacturing a honeycomb structure with high dimensional accuracy, and for forming a skinless honeycomb formed body. Try to provide molds.

According to a first aspect of the present invention, there is provided an outer skin, partition walls arranged in a honeycomb shape in the outer skin, and a large number of cells that are partitioned in the partition walls and formed along the axial direction so as to penetrate both ends. In a method for producing a honeycomb structure having:
Extrusion step of obtaining a skinless honeycomb formed body in which the end of the partition wall is exposed on the outer peripheral side without providing a skin by extruding a ceramic raw material obtained by kneading at least the raw material powder and water;
A drying step of drying the skinless honeycomb formed body,
The skinless honeycomb molded body has a skin formation / heat treatment step for disposing a skin covering the outer peripheral side surface without performing machining and performing a heat treatment to obtain a honeycomb structure,
The extrusion molding process includes a feed hole formed on the hole forming surface for supplying the material, and a groove forming which is a surface opposite to the hole forming surface for forming the material in a honeycomb shape in communication with the supply hole. A die body having a polygonal lattice-shaped slit groove formed on the surface, and a guide ring provided so as to abut on the groove forming surface in order to regulate the outer diameter of the skinless honeycomb molded body. And the supply hole of the mold body does not exist on the outer peripheral side of the minimum inner diameter position of the guide ring or is closed so that no material enters, and the guide ring is formed on the groove forming surface. In contrast, the present invention provides a method for manufacturing a honeycomb structure using a die having an inner peripheral surface having an inclination within a range of 100 ° ± 5 °.

  The most notable point of the method for manufacturing a honeycomb structure of the present invention is to extrude a skinless honeycomb molded body with high dimensional accuracy using a mold for molding a skinless honeycomb molded body having the above specific structure, and then The outer skin is formed on the outer peripheral side surface of the skinless honeycomb molded body without machining. Thereby, a honeycomb structure with high dimensional accuracy can be easily manufactured.

Specifically, in the extrusion molding step, a mold composed of a mold body and a guide ring is used as a mold for forming the skinless honeycomb molded body having the specific shape.
The mold body is formed with a supply hole formed on a hole forming surface for supplying a material, and a groove formed on the opposite side of the hole forming surface to form a material in a honeycomb shape in communication with the supply hole. It has a polygonal lattice slit groove formed on the surface. The guide ring is provided so as to contact the groove forming surface in order to regulate the outer diameter of the skinless honeycomb formed body. Further, the supply hole of the mold body does not exist on the outer peripheral side of the minimum inner diameter position of the guide ring or is closed so that no material enters.

  By providing the guide ring so as to be in contact with the groove forming surface, and by adopting a structure in which no material is supplied from the outer peripheral side of the minimum inner diameter position of the guide ring, the material extruded from the slit groove is Thus, a skinless honeycomb formed body having a shape in which the end of the partition wall is exposed on the outer peripheral side surface is provided.

Further, as described above, the inner peripheral surface of the guide ring has an inner peripheral surface having an inclination within a range of 100 ° ± 5 ° with respect to the groove forming surface.
Thereby, it can shape | mold with a smooth shape, without disturbing the shape of the outer peripheral side surface of the said skinless honeycomb molded object.

That is, when extrusion molding is performed using a mold for forming a skinless honeycomb molded body having the above-described configuration, a skinless honeycomb molded body in which the end of the partition wall is exposed to the outer peripheral side surface without having an outer skin has excellent dimensions. It can be easily obtained with accuracy.
Since the skinless honeycomb molded body thus obtained has excellent dimensional accuracy, the skin formation / heat treatment process is smoothly performed without performing conventional machining such as grinding of the outer peripheral side surface after the drying process. be able to. Therefore, problems such as deformation and cracking in the subsequent process can be reduced, and a honeycomb structure having excellent dimensional accuracy can be obtained and costs can be reduced.
Thereby, according to this invention, the manufacturing method of the honeycomb structure which can manufacture a honeycomb structure with high dimensional accuracy easily can be provided.

The second invention has partition walls arranged in a honeycomb shape without an outer skin, and a large number of cells that are partitioned in the partition walls and formed along the axial direction so as to penetrate both ends. And a mold for forming a skinless honeycomb molded body in which the end of the partition wall is exposed on the outer peripheral side surface,
A supply hole formed on the hole forming surface for supplying the material, and a multi-hole formed on the groove forming surface which is the surface opposite to the hole forming surface for forming the material into the honeycomb shape in communication with the supply hole. A mold main body having a square lattice slit groove;
A guide ring provided to abut on the groove forming surface in order to regulate the outer diameter of the skinless honeycomb molded body,
And the supply hole of the mold body does not exist on the outer peripheral side of the minimum inner diameter position of the guide ring or is blocked so that the material does not enter,
The guide ring is in a mold for forming a skinless honeycomb molded body, characterized in that the guide ring has an inner peripheral surface having an inclination within a range of 100 ° ± 5 ° with respect to the groove forming surface.

When the mold of the present invention is used, as described above, a skinless honeycomb molded body having excellent dimensional accuracy can be easily obtained.
Therefore, according to this invention, the metal mold | die which can manufacture a skinless honeycomb molded object with a high dimensional accuracy easily can be provided.

As described above, in the die for forming a skinless honeycomb formed body used in the method for manufacturing a honeycomb formed body of the first invention, the guide ring is inclined within a range of 100 ° ± 5 ° with respect to the groove forming surface. Having an inner peripheral surface.
When the inclination of the inner peripheral surface is less than 95 ° with respect to the groove forming surface, a partial outer skin is formed on the outer peripheral portion of the skinless honeycomb molded body, which is used when the outer skin is disposed in a later step. There is a problem in that the adhesion between the coating material and the honeycomb body is reduced, and defects such as peeling occur after firing the outer skin. On the other hand, if it exceeds 105 ° with respect to the groove forming surface, the skinless honeycomb molded body and the guide ring Since the load generated at the place where the contact is made becomes local, there is a problem that the outer peripheral portion cannot be formed in a uniform and smooth shape in the axial direction without disturbing the shape of the outer peripheral side surface.

Moreover, it is preferable that the axial direction length of the internal peripheral surface of the said guide ring is the range of 9-12 mm.
When the axial length of the inner peripheral surface is less than 9 mm, the strength of the guide ring is reduced, and the guide ring is deformed by the pressure generated when the skinless honeycomb molded body is extruded, so that the desired shape is obtained. There is a possibility that a skinless honeycomb molded body may not be obtained, and when the axial length exceeds 12 mm, a partial skin is formed on the outer peripheral portion of the skinless honeycomb molded body, At the time of disposing, the degree of adhesion between the coating material and the skinless honeycomb body is lowered, and there is a possibility that defects such as peeling occur after the outer shell is fired.

  The mold body of the mold has a structure in which a supply hole is opened only in a portion located inside the inner peripheral surface of the guide ring. Specifically, as described above, the supply hole is not provided from the beginning outside the minimum inner diameter position of the guide ring, or the opening portion of the provided supply hole is closed.

  Further, in the method for manufacturing a honeycomb structured body according to the first aspect of the present invention, the skin formation / heat treatment step includes an outer skin disposing step of disposing a coating material to be ceramicized by subsequent firing as an outer skin, and firing the outer skin. It is preferable to have a firing step (claim 2).

The firing temperature varies depending on the type of the coating material, but the heat treatment is performed in a temperature range exceeding at least 1200 ° C.
Further, in the case where a preliminary firing step as described later is not performed before the firing step, not only the above-described coating material but also the ceramic raw material constituting the skinless honeycomb formed body can be made into a ceramic by this firing. . In this case, a honeycomb structure excellent in heat resistance and impact resistance can be obtained by a single firing.

Further, the skin formation / heat treatment step may include a preliminary firing step of firing the skinless honeycomb formed body in advance before the outer skin disposing step. That is, baking may be performed twice.
The preliminary firing is preferably performed under the condition that the ceramic raw material constituting the skinless honeycomb formed body is sufficiently ceramicized.
For example, when the ceramic raw material is a cordierite forming raw material, it is preferably pre-fired in a temperature range of 1300 to 1450 ° C.

  When the preliminary firing step is performed, the skinless honeycomb formed body can be ceramicized in advance before disposing the outer skin, and deformation / cracking and the like in the subsequent steps can be suppressed. Therefore, a honeycomb formed body with better dimensional accuracy can be obtained.

The coating material does not contain a pore former, and cordierite, aluminum titanate, silicon carbide, mullite, alumina, silicon nitride, a cordierite-forming raw material that becomes cordierite by firing, and a mullite that becomes mullite by firing. It is preferable to contain 1 type or 2 types or more among raw materials.
In this case, since the coating material does not contain a pore-forming material, a dense outer skin with less unevenness can be obtained, and a useless catalyst consumed for filling the unevenness becomes unnecessary, and the amount of catalyst supported is reduced. Can be made. Therefore, cost can be reduced and excellent dimensional accuracy can be maintained.

  Also, it contains one or more of cordierite, aluminum titanate, silicon carbide, mullite, alumina, silicon nitride, a cordierite forming raw material that becomes cordierite by firing, and a mullite forming raw material that becomes mullite by firing. Thus, it is possible to obtain a honeycomb formed body having a skin particularly excellent in heat resistance and impact resistance by firing.

  In the first aspect of the invention, the skin formation / heat treatment step includes a pre-baking step of firing the skinless honeycomb formed body in advance, and a coating material containing a sol material that is cured by the subsequent curing heat treatment as an outer skin. An outer skin disposing step to be provided and a curing heat treatment step for curing the outer skin may be included (claim 5).

The preliminary firing is preferably performed under the condition that the ceramic raw material constituting the skinless honeycomb formed body is sufficiently ceramicized.
For example, when the ceramic raw material is a cordierite forming raw material, it is preferably pre-fired in a temperature range of 1300 to 1450 ° C.

  When the preliminary firing step is performed, the skinless honeycomb formed body can be ceramicized in advance before disposing the outer skin, and deformation / cracking and the like in the subsequent steps can be suppressed. Therefore, a honeycomb formed body with better dimensional accuracy can be obtained.

  The curing heat treatment is a heat treatment for curing the coating material in a temperature range of 1000 ° C. or lower, and can be performed at a relatively low temperature, so that cost can be reduced.

The coating material preferably does not contain a pore former but contains silica sol or alumina sol.
In this case, since the coating material does not contain a pore-forming material, a dense outer skin with less unevenness can be obtained, and a useless catalyst consumed for filling the unevenness becomes unnecessary, and the amount of catalyst supported is reduced. Can be made. Therefore, cost can be reduced and excellent dimensional accuracy can be maintained.

  The silica sol and alumina sol can be cured by a curing heat treatment performed at a relatively low temperature to have heat resistance and impact resistance. Therefore, it is possible to form a skin having excellent heat resistance and impact resistance at low cost and with high dimensional accuracy.

The coating material preferably further contains one or more of cordierite, aluminum titanate, silicon carbide, mullite, alumina, and silicon nitride (Claim 7).
In this case, the heat resistance and impact resistance can be further improved by further containing the ceramic particles.

The skinless honeycomb molded body before the skin formation / heat treatment step preferably has a flatness ratio of 0.008 to 0.016.
The flatness is a value obtained by (L−l) / L, where L is the diameter of the circumscribed circle of the outermost periphery of the cross section and l is the diameter of the inscribed circle.

  When the flatness ratio of the skinless honeycomb molded body before the skin formation / heat treatment process exceeds 0.016, machining such as grinding of the outer periphery of the skinless honeycomb molded body is required before the skin formation / heat treatment process. There is a risk of becoming.

The honeycomb structure after the skin formation preferably has a flatness ratio of 0.001 to 0.004.
When the flatness of the honeycomb structure after the skin formation exceeds 0.004, there is a possibility that machining such as grinding of the outer peripheral side surface of the honeycomb structure may be required to obtain a desired shape.

The skinless honeycomb molded body is made of cordierite, aluminum titanate, silicon carbide, mullite, alumina, silicon nitride, a cordierite forming raw material that becomes cordierite by firing, and a mullite forming raw material that becomes mullite by firing. It is preferable that it consists of 1 type (s) or 2 or more types (Claim 10).
In this case, in the skin formation / heat treatment step, the raw material of the skinless honeycomb molded body can be particularly well ceramicized, and in particular, a honeycomb molded body excellent in heat resistance and impact resistance can be obtained. .

(Example 1)
In this example, an embodiment according to the present invention will be described with reference to FIGS.
The manufacturing method of the honeycomb structure of the present example includes an extrusion molding step of obtaining a skinless honeycomb molded body by extruding a ceramic raw material obtained by kneading at least a raw material powder and water, and drying the skinless honeycomb molded body. And a skin forming / heat treatment step of disposing a skin covering the outer peripheral side surface of the skinless honeycomb molded body and performing a heat treatment to obtain a honeycomb structure.
This will be described in detail below.

As shown in FIG. 1, a honeycomb structure 1 obtained by this example includes an outer skin 11, partition walls 12 arranged in a honeycomb shape in the outer skin 11, partitions in the partition walls 12, and at both ends. And a large number of cells 13 formed along the axial direction so as to penetrate therethrough.
Moreover, the size of the honeycomb structure manufactured by the method of this example includes, for example, a diameter W of 125 to 175 mm and a height H of 40 to 205 mm. In the following, an example in which the partition wall 12 thickness is 0.3 mm and the cell pitch, that is, the length of one side is 1.47 mm will be described.

  Moreover, as shown in FIG. 2, the skinless honeycomb molded body 14 obtained by the extrusion molding process is in a state in which the end 15 of the partition wall 12 is exposed on the outer peripheral side surface without providing a skin.

  As shown in FIG. 3, the extrusion molding apparatus 9 used in this example has a charging port 92 facing a kneader 91 provided at the upper side, and an upper stage screw 93, an extrusion screw portion 94, below that, A vacuum chamber 95 and a biting roller 96 are provided between the upper screw 93 and the extrusion screw portion 94. The extrusion screw portion 94 includes a circular sleeve 97 and a screw 98 that kneads the ceramic raw material and advances the ceramic raw material in the sleeve 97.

A resistance tube 99 for gradually reducing the cross-sectional area through which the ceramic raw material extruded from the extrusion screw portion 94 passes is provided in front of the extrusion screw portion 94. Further, a mold 3 including a mold body 4 and a guide ring 5 for forming the ceramic raw material extruded from the resistance tube 99 into a skinless shape is disposed in front of it.
Moreover, although the extrusion molding apparatus 9 of this example has the upper stage screw 93 and the extrusion screw part 94, you may provide a middle stage screw between the upper stage screw 93 and the extrusion screw part 94 further.

  As shown in FIG. 4, the mold 3 is provided so as to abut on the mold body 4 and the groove forming surface 42 of the mold body 4 in order to regulate the outer diameter of the skinless honeycomb molded body. It consists of a ring 5. The minimum inner diameter D of the guide ring 5 is 125 mm.

FIG. 5 shows a partially enlarged view of the mold body 4. The mold body 4 includes a supply hole 411 formed in the hole forming surface 41 for supplying the material, and a hole opposite to the hole forming surface 41 for forming the material in a honeycomb shape in communication with the supply hole 411. And a square lattice slit groove 421 formed on the groove forming surface 42 which is a surface.
As is known from the figure, the supply holes 411 are provided at regular intervals at the intersections of the slit grooves 421.

FIG. 6 shows a cross-sectional view of the mold 3. As can be seen from the figure, the mold 3 has a blocking plate 6 so that the supply hole 411 of the mold body 4 does not enter the material from the outer peripheral side of the minimum inner diameter position P of the guide ring 5. It is blocked by
Further, the guide ring 5 has an inner peripheral surface 51 having an inclination θ of 100 ° with respect to the groove forming surface 42, and a back surface 52 including a corner portion of the minimum inner diameter position P of the inner peripheral surface 51 is the groove forming. It is in contact with the surface 42.
The guide ring 5 has an axial length Q of 9.14 mm.

Next, a method for manufacturing a honeycomb formed body will be described.
First, as shown in FIG. 3, a cordierite-forming raw material that becomes cordierite by firing in a later step and water are kneaded by a kneader 91 to obtain a ceramic raw material. Thereafter, the ceramic raw material is charged from the kneading machine 91 into the raw material charging port 92, and this is fed into the extrusion screw portion 94 via the vacuum chamber 95 and the biting roller 96 by the propulsive force by the rotation of the upper screw 93. It is.

  Thereafter, the ceramic raw material is extruded from the extrusion screw portion 94, the passing cross-sectional area is gradually reduced in the resistance tube 99, and the die 3 is pushed out from the die body 4 and passed through the guide ring 5, thereby causing the skin. A less honeycomb formed body 14 was formed.

Next, as a drying process, microwave drying was performed by irradiating microwaves using a microwave generator.
Thereafter, the skinless honeycomb formed body was cut into a desired length.

Next, a coating material made of a cordierite-forming raw material that becomes cordierite by firing in the subsequent step was prepared.
Then, as the skin formation / heat treatment step, a skin placement step of placing the coating material as a skin and a firing step for firing the skin were performed to obtain a honeycomb structure.

In the outer skin arranging step, a coating material is applied to a range 2 mm larger than the maximum outer diameter of the skinless honeycomb molded body, and a cylinder having an inner diameter 0.5 to 1.5 mm larger than the maximum outer diameter of the skinless honeycomb molded body The coating material was scraped off with a shape jig.
The firing process starts at a furnace temperature of 20 ° C., increases to 100 ° C. over 0.5 hours, further increases to 1400 ° C. over 9.5 hours, and 1430 ° C. over 5 hours. The temperature was raised to 1,430 ° C. for 30 hours, and then cooled to 20 ° C. over 5 hours. FIG. 7 shows the relationship (K) between the furnace temperature and the elapsed time in the firing process. In FIG. 7, the vertical axis represents the furnace temperature (° C.), and the horizontal axis represents the elapsed time (Hr).

In this firing step, the ceramic raw material constituting the skinless honeycomb formed body and the coating material constituting the outer skin were made to be cordierite.
Thereby, according to this example, the honeycomb structure with high dimensional accuracy and excellent heat resistance and impact resistance can be easily manufactured.

(Example 2)
This example is an example in which the skin formation / heat treatment process of Example 1 is changed.
Specifically, in the present example, in the skin formation / heat treatment step, a preliminary firing step of firing the skinless honeycomb formed body in advance is performed before the outer skin disposing step.
The pre-baking step starts at a furnace temperature of 20 ° C., is heated to 800 ° C. over 30 hours, further heated to 1400 ° C. over 10 hours, held at 1400 ° C. for 3 hours, and then 5 hours Over cooling to 20 ° C.
In this preliminary firing step, the skinless honeycomb formed body was preliminarily formed into cordierite. Others were performed in the same manner as in Example 1.
Thereby, according to this example, the honeycomb structure with high dimensional accuracy and excellent heat resistance and impact resistance can be easily manufactured.

  Moreover, in Example 1 and Example 2, the cordierite-forming raw material that becomes cordierite by firing was used as the ceramic raw material and the coating material, but instead of this, cordierite, aluminum titanate, silicon carbide, mullite, Alumina, silicon nitride, a mullite raw material that becomes mullite by firing, or the like may be used.

(Example 3)
This example is an example in which the skin formation / heat treatment process of Example 2 is changed. Others were the same as in Example 2.
Specifically, a coating material made of silica sol and cured by a post-curing heat treatment was prepared as the coating material.

  As the skin formation / heat treatment step, a preliminary firing step for firing the skinless honeycomb formed body in advance, a skin placement step for placing the coating material as a skin, and a curing heat treatment step for curing the skin went.

The preliminary firing step and the outer skin disposing step were performed in the same procedure as in Example 2.
The curing heat treatment step starts at a furnace temperature of 20 ° C., raises the temperature to 100 ° C. over 0.5 hours, further increases the temperature to 650 ° C. over 2.5 hours, and continues at 650 ° C. for 2 hours. After holding, it was performed by cooling to 20 ° C. over 2 hours. FIG. 8 shows the relationship (L) between the furnace temperature and the elapsed time in the hardening heat treatment step. In FIG. 8, the vertical axis represents the furnace temperature (° C.) and the horizontal axis the elapsed time (Hr).
As a result, it was possible to easily manufacture a honeycomb structure having high dimensional accuracy and excellent heat resistance and impact resistance.

  Further, in this example, silica sol was used as the coating material, but alumina sol may be used instead, and ceramic particles such as cordierite, aluminum titanate, silicon carbide, mullite, alumina, and silicon nitride may be used. You may make it contain.

Example 4
This example is an example in which the mold of Example 1 is changed.
FIG. 9 shows a cross-sectional view of the mold 7 used in this example. As is known from FIG. 9, the mold 7 includes a mold body 8 and a guide ring 5 similar to that of the first embodiment.
The mold body 8 includes a supply hole 811 formed in the hole forming surface 81 for supplying the material, and an opposite side of the hole forming surface 81 for forming the material into the honeycomb shape in communication with the supply hole 811. And a square lattice slit groove 821 formed on the groove forming surface 82 which is a surface. The supply hole 811 of the mold body 8 does not exist on the outer peripheral side of the minimum inner diameter position P of the guide ring 5.
Others were performed in the same manner as in Example 1.
According to the present invention, a honeycomb structure having high dimensional accuracy and excellent heat resistance and impact resistance could be easily manufactured.

FIG. 3 is an explanatory view showing a honeycomb structure in Example 1. FIG. 3 is an explanatory view showing a skinless honeycomb formed body in Example 1. BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 3 is an explanatory view showing a mold in Example 1. FIG. 3 is an enlarged view showing a mold body in the first embodiment. Sectional drawing which shows the metal mold | die in Example 1. FIG. The graph which shows the relationship between the furnace temperature and elapsed time of a baking process in Example 1. FIG. The graph which shows the relationship between the furnace temperature and elapsed time of a baking process in Example 3. FIG. Sectional drawing which shows the metal mold | die in Example 4. FIG.

Explanation of symbols

3 Mold 4 Mold body 41 Hole forming surface 411 Supply hole 42 Groove forming surface 421 Slit groove 5 Guide ring

Claims (11)

A honeycomb structure having an outer skin, partition walls arranged in a honeycomb shape in the outer skin, and a large number of cells that are partitioned in the partition walls and formed along the axial direction so as to penetrate both ends In the way to
Extrusion step of obtaining a skinless honeycomb formed body in which the end of the partition wall is exposed on the outer peripheral side without providing a skin by extruding a ceramic raw material obtained by kneading at least the raw material powder and water;
A drying step of drying the skinless honeycomb formed body,
The skinless honeycomb molded body has a skin formation / heat treatment step for disposing a skin covering the outer peripheral side surface without performing machining and performing a heat treatment to obtain a honeycomb structure,
The extrusion molding process includes a feed hole formed on the hole forming surface for supplying the material, and a groove forming which is a surface opposite to the hole forming surface for forming the material in a honeycomb shape in communication with the supply hole. A die body having a polygonal lattice-shaped slit groove formed on the surface, and a guide ring provided so as to abut on the groove forming surface in order to regulate the outer diameter of the skinless honeycomb molded body. And the supply hole of the mold body does not exist on the outer peripheral side of the minimum inner diameter position of the guide ring or is closed so that no material enters, and the guide ring is formed on the groove forming surface. A method for manufacturing a honeycomb structure, comprising using a mold having an inner peripheral surface having an inclination within a range of 100 ° ± 5 °.   The skin formation / heat treatment step according to claim 1, wherein the skin formation / heat treatment step includes a skin placement step of placing a coating material that becomes ceramic by firing as a skin, and a firing step for firing the skin. A method for manufacturing a honeycomb structure.   3. The method for manufacturing a honeycomb structure according to claim 2, wherein the skin formation / heat treatment step includes a preliminary firing step of firing the skinless honeycomb formed body in advance before the outer skin disposing step.   4. The coating material according to claim 2 or 3, wherein the coating material does not contain a pore former, and cordierite, aluminum titanate, silicon carbide, mullite, alumina, silicon nitride, a cordierite forming raw material that becomes cordierite by firing, A method for manufacturing a honeycomb structure, comprising one or more mullite raw materials to be converted into mullite.   2. The skin formation / heat treatment step according to claim 1, wherein the skin formation / heat treatment step includes a preliminary firing step of firing the skinless honeycomb formed body in advance and a coating material containing a coating material containing a sol material cured by the subsequent curing heat treatment as an outer skin. A method for manufacturing a honeycomb structure, comprising: a setting step; and a curing heat treatment step for curing the outer skin.   6. The method for manufacturing a honeycomb structure according to claim 5, wherein the coating material does not contain a pore forming material but contains silica sol or alumina sol.   7. The method for manufacturing a honeycomb structure according to claim 6, wherein the coating material further contains one or more of cordierite, aluminum titanate, silicon carbide, mullite, alumina, and silicon nitride.   The honeycomb structure according to any one of claims 1 to 7, wherein the skinless honeycomb formed body before the skin formation / heat treatment step has a flatness ratio of 0.008 to 0.016. Method.   The method for manufacturing a honeycomb structure according to any one of claims 1 to 8, wherein the honeycomb structure has a flatness ratio of 0.001 to 0.004.   In any one of Claims 1-9, the raw material of the skinless honeycomb formed body is cordierite, aluminum titanate, silicon carbide, mullite, alumina, silicon nitride, a cordierite-forming raw material that becomes cordierite by firing, A method for manufacturing a honeycomb structure, comprising one or more of mullitized raw materials that become mullite by firing. The partition wall end without the outer shell, and a plurality of cells that are partitioned in the partition wall and formed along the axial direction so as to penetrate both ends, the partition wall end portion Is a mold for forming a skinless honeycomb molded body with the outer peripheral side exposed,
A supply hole formed on the hole forming surface for supplying the material, and a multi-hole formed on the groove forming surface which is the surface opposite to the hole forming surface for forming the material into the honeycomb shape in communication with the supply hole. A mold main body having a square lattice slit groove;
A guide ring provided to abut on the groove forming surface in order to regulate the outer diameter of the skinless honeycomb molded body,
The supply hole of the mold body does not exist on the outer peripheral side of the minimum inner diameter position of the guide ring or is closed so that the material does not enter,
The guide ring has an inner peripheral surface having an inclination in a range of 100 ° ± 5 ° with respect to the groove forming surface.

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