JP2008110536A - Extrusion molding machine of honeycomb structure and honeycomb structure manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an extrusion molding machine of a honeycomb structure manufacturing a ceramic honeycomb structure of which the outer shape is oval without causing a flaw such as a fine split, cell collapse, etc. <P>SOLUTION: The extrusion molding machine of the ceramic honeycomb structure has an extrusion screw part 2 equipped with a cylindrical sleeve 21 and a screw 22 for kneading a ceramic raw material to advance it, a flow regulating part 3 having a flow regulating plate 31 for uniformizing the passing speed distribution of the ceramic raw material extruded from the extrusion screw part 2, a resistance pipe 4 for gradually reducing the cross-sectional area through which the ceramic raw material extruded from the flow regulating part 3 is passed, and a mold 5 for molding the ceramic raw material extruded from the resistance pipe 4 into a desired oval shape. The flow regulating plate 31 has a shape changing part 32 for gradually changing the ceramic raw material from a circular shape to the oval shape during the period reaching a flow regulating plate arranging part from an upstream end. The resistance pipe 4 gradually becomes small in its cross-sectional area while keeping the oval shape during the period reaching a downstream end from the upstream end. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an extrusion molding apparatus and manufacturing method for a ceramic honeycomb structure having an oval shape. The “oval shape” in the present specification has a portion having a long diameter (long diameter portion) and a short portion (short diameter portion), and is generally called an ellipse. The concept is not limited to an “ellipse” but includes a so-called racetrack shape combining a semicircle and a straight line, and an intermediate shape between an ellipse and a racetrack shape.

  Ceramic honeycomb structures are widely used as a carrier for automobile exhaust gas purification catalysts. As a method for forming the honeycomb structure, extrusion molding or plunger molding is generally used. In the case of producing by extrusion molding, the kneaded material can be produced by extrusion molding using a molding die, followed by drying and baking.

  Conventionally, an extrusion molding apparatus using an oval-shaped honeycomb structure for extrusion molding, as shown in a comparative example described later, is provided with a rectifying plate immediately after the extrusion screw portion, and adjacent to the rectifying plate, the raw material is molded into a mold. A resistance tube is provided for feeding into the tube. The resistance tube has a circular shape at the upstream end and an oval shape at the downstream end. For this reason, there is a large difference between the diameter reduction ratio in the major axis direction and the diameter reduction ratio in the minor axis direction of the resistance tube, and the speed distribution of the raw material extrusion is non-uniform. Therefore, the raw material does not spread sufficiently in the long diameter direction of the extruded oval-shaped honeycomb structure. Has a problem that cell collapse occurs. Therefore, as a whole, the oval shape is further crushed.

JP 2000-167818 A

  The present invention has been made in view of such conventional problems, and it is possible to manufacture a ceramic honeycomb structure whose outer shape is an oval shape without causing defects such as pouring and cell collapse. An object of the present invention is to provide an extrusion apparatus and manufacturing method for a honeycomb structure.

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. An extrusion apparatus for extruding a ceramic honeycomb structure having an oval outer shape,
An extrusion screw portion comprising a circular sleeve, and a screw that kneads and advances the ceramic raw material in the sleeve;
A rectifying unit having a rectifying plate for homogenizing the passage speed distribution of the ceramic raw material extruded from the extrusion screw unit;
A resistance tube that gradually reduces the cross-sectional area through which the ceramic raw material extruded from the rectifying unit passes;
A molding die for molding the ceramic raw material extruded from the resistance tube into a desired oval shape,
The rectifying plate has, from the upstream end to the rectifying plate disposition portion, a circular shape having an inner diameter substantially the same as the inner diameter of the sleeve, a short diameter equal to or greater than the inner diameter, and a long diameter larger than the short diameter. It has a shape change part that gradually changes to an oval shape, and the shape of the rectifying plate and the inner shape of the downstream short are oval shapes,
The above-mentioned resistance tube is connected to the above-mentioned molding die with the cross-sectional area gradually decreasing while maintaining the oval shape from the upstream end to the downstream end. (Claim 1).

  In the honeycomb structure extrusion molding apparatus of the present invention, the most notable point is that a rectifying unit having a shape changing portion that gradually changes from a circular shape to an oval shape is provided, and the resistance tube is maintained in an oval shape. The diameter is gradually reduced as it is. In other words, by providing the rectifying unit, the flow rate distribution can be satisfactorily made uniform in the oval shape in the rectifying plate. The cross-sectional area can be reduced in a state where there is no great difference in the diameter reduction ratio. Thereby, extrusion molding can be performed in a state where the extrusion speed distribution is uniform. Therefore, even if the resulting honeycomb structure has an oval shape, there are almost no defects such as crushing and cell crushing.

  The rectifying part has a shape changing part as described above, and has a circular shape at the upstream end for smooth contact with the sleeve. The shape is an oval shape. The shape changing portion gradually changes to an oval shape having a short diameter equal to or greater than the inner diameter of the upstream end of the rectifying portion and a long diameter larger than the short diameter. Thereby, when the ceramic raw material passes through the oval-shaped rectifying plate, it is possible to make the passage speed distribution uniform.

  In addition, the resistance tube gradually decreases in cross-sectional area while maintaining the oval shape from the upstream end to the downstream end. That is, in the resistance tube, the difference between the diameter reduction rate in the major axis direction and the diameter reduction rate in the minor axis direction is small. Thereby, in the resistance tube, the passage speed distribution of the ceramic raw material can be kept uniform. Therefore, the extrusion speed distribution of the ceramic raw material extruded from the molding die can be made uniform.

  As described above, according to the present invention, by providing the rectifying portion and limiting the shape of the resistance tube, the ceramic honeycomb structure whose outer shape is an oval shape causes defects such as rolling and cell collapse. It is possible to provide an extrusion molding apparatus that can be manufactured without any problems.

According to a second aspect of the present invention, there is provided an outer skin, a partition wall arranged in a honeycomb shape in the outer skin, and a large number of cells that are partitioned in the partition wall and formed along the axial direction so as to penetrate both ends. A method for manufacturing a ceramic honeycomb structure having an oval outer shape,
At the time of kneading and extrusion molding a ceramic raw material containing at least raw material powder and water, the cross-sectional shape of the ceramic raw material extruded from the extrusion screw portion using the extrusion molding apparatus according to the first invention is The oval shape is changed to the oval shape on the upstream side of the rectifying plate in the rectifying unit, and thereafter the passage cross-sectional area is gradually reduced while maintaining the oval shape in the resistance tube, and then the oval shape is formed by the molding die. A feature of the manufacturing method of the honeycomb structure is (Claim 6).

As described above, the method for manufacturing a honeycomb structure of the present invention uses the extrusion molding apparatus described in the first invention for extrusion molding. Therefore, in a state where the extrusion rate distribution of the ceramic raw material is uniform, Extrusion can be performed.
As described above, according to the present invention, there is provided a method for manufacturing a honeycomb structured body capable of manufacturing a honeycomb structure made of ceramic having an oval outer shape without causing defects such as rolling and cell collapse. Can be provided.

In the honeycomb structure extrusion molding apparatus according to the first aspect of the invention, the inner shape of the downstream end of the rectifying portion is preferably an oval shape having a ratio of the major axis to the minor axis of 1.1 or more. .
The effect of the present invention can be remarkably obtained when the ratio of the major axis to the minor axis is 1.1 or more, preferably 1.3 or more.

In the resistance tube, it is preferable that the major diameter reduction ratio A and the minor diameter reduction ratio B have a relationship of 0.9 <A / B <1.1.
In this case, the passage speed distribution can be made uniform, and distortion and the like can be prevented from occurring during extrusion molding.

  In addition, when the relationship between the major diameter reduction ratio A and the minor diameter reduction ratio B is 0.9 ≧ A / B, the ceramic raw material flowing toward the minor axis portion becomes excessive. Cell collapse may occur in the partial direction. On the other hand, when A / B ≧ 1.1, since the ceramic raw material flowing in the direction of the long diameter portion becomes excessive, cell collapse may occur in the direction of the long diameter portion.

The resistance tube preferably has a major diameter reduction ratio A and a minor diameter reduction ratio B both of 0.7 or less.
In this case, it is possible to further suppress the occurrence of distortion during extrusion molding.
In addition, when either the major diameter reduction ratio A or the minor diameter reduction ratio B exceeds 0.7, the ceramic raw material separated by the rectifying plate may not be combined again, or the ceramic raw material does not reach the skin. , There is a risk that a bite will occur.

The inner shape of the upstream end and the downstream end of the resistance tube is preferably a similar shape.
That is, the inner shape of the resistance tube only needs to maintain an oval diameter shape, and the object can be achieved even if the shape changes slightly. However, as described above, when the diameter is similar from the upstream end to the downstream end of the resistance tube, it is most ideal because the diameter reduction rate in the entire circumference does not change. In this case, the extrusion speed distribution can be further uniformed.

(Example 1)
In this example, an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 shows an overall view of an extrusion molding apparatus. FIG. 2A shows a cross-sectional view in the direction of the major axis of the extrusion molding apparatus, and FIG. 2B shows a cross-sectional view in the direction of the minor axis.
As shown in FIG. 1, an extrusion molding apparatus 1 for a honeycomb structure used in this example has an inlet 12 facing a kneading machine 11 provided above, and an upper stage screw 13 and an extrusion screw below that. 22, a vacuum chamber 14 and a biting roller 15 are provided between the upper screw 13 and the extrusion screw 22.

The rectifying unit 3 is provided in front of the extrusion screw 22, and the resistance tube 4 is further provided in front of the rectifying unit 3. A guide ring 16 is provided in the molding die 5, and a sponge cradle 17 that supports the extruded honeycomb structure 6 is provided in front of the guide ring 16.
Moreover, although the extrusion molding apparatus 1 of this example has the upper stage screw 13 and the extrusion screw 22, you may provide a middle stage screw further between the upper stage screw 13 and the extrusion screw 22. FIG.
This will be described in detail below.

  As shown in FIG. 2, the extrusion molding apparatus 1 includes an extrusion screw portion 2 that includes a circular sleeve 21, a screw 22 that kneads and advances the ceramic raw material in the sleeve 21, and the extrusion screw portion 2. A rectifying unit 3 having a rectifying plate 31 for equalizing the passage speed distribution of the ceramic raw material extruded from the rectifier, and a resistance tube 4 for gradually reducing the cross-sectional area through which the ceramic raw material extruded from the rectifying unit 3 passes. And a molding die 5 for molding the ceramic raw material extruded from the resistance tube 4 into a desired oval shape.

  The rectifying unit 3 has a circular shape having an inner diameter substantially the same as the inner diameter of the sleeve 21 from the upstream end to the rectifying plate disposing unit, a short diameter equal to or greater than the inner diameter, and a long diameter larger than the short diameter. The shape change part which changes gradually into the oval shape having the shape is formed, and the shape of the rectifying plate 31 and the inner shape of the downstream end are oval shapes.

The inner shape of the downstream end of the rectifying unit 3 is an oval shape having a major axis of 240 mm and a minor axis of 190 mm, that is, the ratio of the major axis to the minor axis is 1.26.
Further, as shown in FIG. 3, the rectifying plate 31 has a large number of holes 33 for allowing the ceramic raw material to pass through, and the diameter of the holes 33 is φ5 mm. Further, as shown in the figure, the rectifying plate 31 has an oval shape having a major axis W1 of 270 mm and a minor axis H1 of 220 mm, and has a thickness of 30 mm. In addition, a region S having the same size as the downstream end of the rectifying unit (the major axis W2 is 240 mm and the minor axis H2 is 190 mm) is a region through which the ceramic raw material actually passes.

Between the upstream end and the downstream end, the resistance tube 4 is connected to the molding die 5 with the sectional area gradually decreasing while maintaining the oval shape.
4A shows the upstream end of the resistance tube 4, FIG. 4B shows the cross section of the resistance tube 4, and FIG. 4C shows the downstream end of the resistance tube 4.
As shown in FIG. 4A, the inner shape of the resistance tube 4 is an oval shape with the major axis H3 of 240 mm and the minor axis W3 of 190 mm at the upstream end. As shown in FIG. 4B, the distance L between the upstream end and the downstream end is 355 mm. Further, as shown in FIG. 4C, the downstream end has an oval shape having a major axis W4 of 170 mm and a minor axis H4 of 130 mm. That is, the major diameter reduction ratio A and the minor diameter reduction ratio B are 0.7, and the major diameter reduction ratio A and the minor diameter reduction ratio B have a relationship of A / B = 1. Therefore, the inner shape of the upstream end and the downstream end of the resistance tube 4 is similar.

The inner shape of the molding die 5 is an oval shape having a major axis W5 of 170 mm and a minor axis H5 of 115 mm, as shown in FIG. FIG. 5B is a side view of the molding die 5.
The inner shape of the guide ring 16 is an oval shape having a major axis W6 of 154 mm and a minor axis H6 of 98 mm as shown in FIG. This oval shape is substantially similar to the final molded product. FIG. 6B shows a cross-sectional shape of the guide ring 16.

Next, a method for manufacturing a honeycomb structure will be described.
The honeycomb structure manufactured by this example is mainly composed of cordierite having a theoretical composition represented by 2MgO · 2Al ₂ O ₃ · 5SiO ₂ . Usually, cordierite, the SiO ₂ from 49.0 to 53.0 wt%, the Al ₂ O ₃ 33.0 to 37.0 wt%, containing MgO in a proportion of 11.5 to 15.5 wt% To do.

Therefore, as the ceramic raw material, a material obtained by adding and kneading a molding aid to a cordierite-forming raw material adjusted to have a desired cordierite composition is used. Cordierite-forming raw materials include talc (Mg ₃ Si ₄ O ₁₀ (OH) ₂ ), carrion (Al ₂ Si ₂ O ₅ (OH) ₄ ), alumina (Al ₂ O ₃ ), aluminum hydroxide (Al ( OH) ₃ ) and the like. Further, Mg source, Al source, Si source oxide, hydroxide, chloride and the like can be used. Examples include serpentine (Mg ₃ Si ₂ O ₅ (OH) ₄ ), pyroferrite (Al ₂ Si ₄ O ₁₀ (OH) ₂ ), and brucite (Mg (OH) ₂ ).

  Moreover, as a molding aid added to the cordierite-forming raw material, commonly used lubricants, humectants, binders, and the like can be used. Examples of lubricants and humectants include waxes, water-soluble polyhydric alcohol derivatives, and surfactants. Examples of the binder include methyl cellulose and polyvinyl alcohol.

  First, as shown in FIG. 1, the cordierite-forming raw material and the forming aid were kneaded by a kneader 11 to obtain a ceramic raw material. Thereafter, the ceramic raw material is charged into the raw material charging port 12 from the kneader 11 and is fed into the screw 22 via the vacuum chamber 14 and the biting roller 15 by the propulsive force generated by the rotation of the upper screw 13.

Thereafter, the ceramic raw material is extruded from the extrusion screw portion 2, and the cross sectional shape of the ceramic raw material is changed to an oval shape on the upstream side of the rectifying plate 31 in the rectifying portion 3, and then the oval shape in the resistance tube 4. The oval-shaped honeycomb structure 6 is formed by gradually decreasing the passage cross-sectional area while maintaining the above, extruding from the molding die 5 and passing through the guide ring 16. The extrusion conditions are an extrusion pressure of 100 to 200 kg / cm ² , an extrusion speed of 1.0 to 2.0 m / min, and a raw material temperature of 10 to 20 ° C.

The extruded honeycomb structure 6 is supported by the sponge cradle 17 and fed forward.
Next, after the extrusion molding, the honeycomb structure 6 is cut to a predetermined length while being placed on the sponge cradle 17. Then, the separated individual honeycomb structures 6 were left on the sponge cradle 17 for 1 hour as they were to perform a drying process.

Next, after the drying process was completed, the honeycomb structure was transported into a firing furnace and fired. Firing was performed under the condition of maintaining the temperature at 1400 ° C. for 5 hours. After the completion of the firing, finishing steps such as removal of cut ends of the individual honeycomb structures were performed to obtain a honeycomb structure having an oval shape.
According to this example, it was possible to obtain a ceramic honeycomb structure having an oval outer shape without causing defects such as pouring and cell collapse.

(Comparative Example 1)
This comparative example shows the comparative example of the present invention with reference to FIG.
This comparative example is an example in which extrusion molding is performed using a conventional extrusion molding apparatus 9 as shown in FIG.
The extrusion apparatus 9 is obtained by changing the rectifying unit 3 and the resistance tube 4 in the first embodiment. That is, the extrusion molding apparatus 9 includes a rectifying unit including only a circular rectifying plate 91 and a resistance tube 92 that changes from a circular shape to an oval shape. Others were performed in the same manner as in Example 1.

  In this comparative example, the ceramic raw material extruded from the extrusion screw portion 2 passes through the rectifying plate 91 in a circular cross-sectional shape, and then the cross-sectional shape in the resistance tube 92 changes from a circular shape to an oval shape. . Since the resistance tube 92 has a large difference in the reduction ratio in the major axis direction and the reduction ratio in the minor axis part direction, the speed distribution of the extrusion of the raw material becomes non-uniform. Therefore, in the honeycomb structure obtained in this example, cell crushing was observed in the direction of the short diameter portion, and crusting was observed in the long diameter direction.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 3 is an explanatory diagram illustrating a current plate in the first embodiment. FIG. 3 is an explanatory diagram illustrating a resistance tube in the first embodiment. FIG. 3 is an explanatory view showing a molding die in Example 1. FIG. 3 is an explanatory view showing a guide ring in the first embodiment. Explanatory drawing which shows the extrusion molding apparatus in the comparative example 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Extrusion molding apparatus 2 Extrusion screw part 21 Sleeve 22 Extrusion screw 3 Rectification part 31 Rectification plate 32 Shape change part 4 Resistance pipe 5 Mold

Claims (6)

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 are formed along the axial direction so as to penetrate both ends. An extrusion apparatus for extruding a ceramic honeycomb structure having an oval shape,
An extrusion screw portion comprising a circular sleeve, and a screw that kneads and advances the ceramic raw material in the sleeve;
A rectifying unit having a rectifying plate for homogenizing the passage speed distribution of the ceramic raw material extruded from the extrusion screw unit;
A resistance tube that gradually reduces the cross-sectional area through which the ceramic raw material extruded from the rectifying unit passes;
A molding die for molding the ceramic raw material extruded from the resistance tube into a desired oval shape,
The rectifying unit has a short diameter equal to or greater than the inner diameter and a major axis larger than the short diameter from a circular shape having an inner diameter substantially the same as the inner diameter of the sleeve, from the upstream end to the rectifying plate disposing portion. It has a shape change part that gradually changes to an oval shape, and the shape of the current plate and the inner shape of the downstream end are oval shapes,
The above-mentioned resistance tube is connected to the above-mentioned molding die with the cross-sectional area gradually decreasing while maintaining the oval shape from the upstream end to the downstream end. .   2. The honeycomb structure extrusion molding apparatus according to claim 1, wherein an inner shape of the downstream end of the rectifying unit is an oval shape in which a ratio of a major axis to a minor axis is 1.1 or more.   The honeycomb according to claim 1 or 2, wherein the resistance tube has a relationship of 0.9 <A / B <1.1 between a major diameter reduction ratio A and a minor diameter reduction ratio B. Structure extrusion molding equipment.   The extrusion of the honeycomb structure according to any one of claims 1 to 3, wherein the resistance tube has both a major diameter reduction ratio A and a minor diameter reduction ratio B of 0.7 or less. Molding equipment.   5. The honeycomb structure extrusion molding apparatus according to claim 1, wherein an inner shape of the upstream end and the downstream end of the resistance tube is a similar shape. 6. 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 are formed along the axial direction so as to penetrate both ends. A method of manufacturing a ceramic honeycomb structure having an oval shape,
In kneading and extruding a ceramic raw material containing at least a raw material powder and water, using the extrusion molding apparatus according to any one of claims 1 to 5, the ceramic raw material extruded from the extrusion screw portion. The passage cross-sectional shape is changed to an oval shape on the upstream side of the rectifying plate in the rectifying unit, and then the passage cross-sectional area is gradually reduced while maintaining the oval shape in the resistance tube, and then the oval is formed by the molding die. A method for manufacturing a honeycomb structure, comprising forming into a shape.

Images