JP2008110537A - Manufacturing method of honeycomb structure and drying device used therein - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a honeycomb structure suppressing the deformation of a honeycomb molded object at the time of drying and preventing trouble such as cracking, wrinkles, etc., and a drying device used therein. <P>SOLUTION: The manufacturing method of the honeycomb structure has a molding process for molding the honeycomb molded object by subjecting a ceramic material, which contains at least a cordierite raw material, water and a binder, to extrusion molding to cut the extrudate into a predetermined length, a drying process for irradiating the honeycomb molded object with a microwave to dry the same, and a firing process for firing the honeycomb molded object to obtain the honeycomb structure. The drying process is divided into a plurality of steps, and in a first step S1, the center temperature of the honeycomb molded object reaches at least the curing start temperature of the binder from the start of drying, wherein the output of the microwave for irradiating the honeycomb molded object in the first step S1 is set higher than the output of the microwave of the subsequent step. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a honeycomb structure used for an exhaust gas purification filter or the like of an internal combustion engine and a drying apparatus used therefor.

  As a ceramic honeycomb structure, one having a large number of cells surrounded by a honeycomb-shaped cell wall and a cylindrical outer peripheral wall covering the outer peripheral side surface is known. A honeycomb structure is generally manufactured by extruding a ceramic material to form a honeycomb formed body, drying it, and firing it.

In manufacturing the honeycomb structure, as a method of drying the honeycomb formed body, there is a method of drying by irradiating microwaves (see Patent Document 1).
However, in the above method, the drying speed of the central portion of the honeycomb formed body is increased, and stress is generated due to a difference in drying shrinkage between the central portion and the outer peripheral portion. In particular, since a large tensile stress is generated in the outer peripheral portion toward the central portion, the cell wall is deformed. As a result, defects such as cracks and wrinkles occur in the outer peripheral wall. In addition, since the microwave output is constant and the temperature rise of the honeycomb formed body is moderate, the state of containing a lot of moisture becomes long, and the above-described problems are likely to occur. In particular, as the cell wall thickness becomes smaller, the above-mentioned problem appears more remarkably.

  For these reasons, there is a demand for a method for manufacturing a honeycomb structure that can suppress deformation during drying of the extruded honeycomb formed body and prevent problems such as cracking and wrinkling of the outer peripheral wall.

JP 2002-283331 A

  The present invention has been made in view of such conventional problems, and is a honeycomb structure that can suppress deformation during drying of an extruded honeycomb formed body and prevent defects such as cracks and wrinkles in the outer peripheral wall. An object of the present invention is to provide a manufacturing method and a drying apparatus used therefor.

A first invention is a method of manufacturing a cordierite ceramic honeycomb structure having a large number of cells surrounded by a honeycomb-shaped cell wall and a cylindrical outer peripheral wall covering an outer peripheral side surface.
A molding step of forming a honeycomb formed body by extruding a ceramic material containing at least a cordierite raw material, water, and a binder and cutting it to a predetermined length;
A drying step of drying the honeycomb formed body by irradiation with microwaves;
A firing step of firing the honeycomb formed body to obtain the honeycomb structure,
In the drying step, the drying step is divided into a plurality of steps, and the first step is from the start of drying until the temperature of the central portion of the honeycomb formed body reaches at least the curing start temperature of the binder. A method for manufacturing a honeycomb structure is characterized in that the microwave output irradiated to the honeycomb formed body is set higher than the microwave output in the subsequent step.

  In the method for manufacturing a honeycomb structured body of the present invention, the drying step is divided into a plurality of steps, and the first step is from the start of drying until the temperature of the central portion of the honeycomb formed body reaches at least the curing start temperature of the binder. And And in this 1st step, the microwave output irradiated to the said honeycomb molded object is set higher than the microwave output of a subsequent step.

  That is, the honeycomb formed body immediately after the forming step still contains a lot of moisture and is easily deformed. In the present invention, the microwave output of the first step, which is the first step among the plurality of steps of the drying process, is made highest. Therefore, the temperature of the honeycomb formed body can be raised early, and moisture contained in the honeycomb formed body can be removed at the earliest possible stage of the drying step. And time until the temperature of the center part of the said honeycomb molded object reaches the hardening start temperature of the said binder can be shortened. That is, the time of the first step can be shortened.

  Thereby, when the time of the said whole drying process is made constant, the time of the said 1st step which occupies for the said whole drying process can be shortened. And the said honeycomb molded object in the said drying process can shorten the state which is easy to deform | transform which contained much moisture. Therefore, deformation of the cell wall at the time of drying can be suppressed, and problems such as cracks and wrinkles can be prevented from occurring on the outer peripheral wall.

  As described above, according to the method for manufacturing a honeycomb structured body of the present invention, it is possible to suppress deformation of the extruded honeycomb formed body during drying and to prevent problems such as cracks and wrinkles on the outer peripheral wall.

According to a second aspect of the present invention, at least a cordierite raw material is used in manufacturing a cordierite ceramic honeycomb structure having a large number of cells surrounded by a honeycomb-shaped cell wall and a cylindrical outer peripheral wall covering the outer peripheral side surface. In a drying apparatus for extruding a ceramic material containing water and a binder and drying the honeycomb formed body cut into a predetermined length,
The drying apparatus includes a drying tank that accommodates the honeycomb formed body, a transport conveyor that continuously transports the honeycomb formed body in the drying tank, and a plurality of the drying apparatuses arranged in the transport direction of the honeycomb formed body in the drying tank. A microwave generator for irradiating the installed microwave,
The drying tank is divided into a plurality of zones, and the microwave generator in the first zone to which the honeycomb formed body is first conveyed is the honeycomb generator while the honeycomb formed body passes through the first zone. The microwave output is configured so that the temperature of the central portion of the molded body reaches at least the curing start temperature of the binder, and the microwave output is higher than other zones. (7).

  In the drying apparatus of the present invention, the drying tank is divided into a plurality of zones, and a first zone is provided in a portion where the honeycomb formed body is first conveyed. The microwave generator in the first zone is configured so that the temperature of the central portion of the honeycomb formed body reaches at least the curing start temperature of the binder while the honeycomb formed body passes through the first zone. The output is set, and the microwave output is set higher than the other zones.

  That is, the honeycomb formed body immediately after extrusion molding still contains a lot of moisture and is in a state of being easily deformed. The drying apparatus of the present invention is a microwave output of the microwave generator in the first zone, which is the first zone among the plurality of zones of the drying tank that carries in and drys the honeycomb formed body after extrusion molding. Is set to the highest value. Therefore, in the first zone, moisture contained in the honeycomb formed body can be removed as much as possible before the binder starts to cure. Accordingly, it is possible to shorten a state in which the honeycomb formed body contains a large amount of moisture and the honeycomb formed body is easily deformed. Therefore, deformation of the cell wall at the time of drying can be suppressed, and problems such as cracking and wrinkling of the outer peripheral wall can be prevented.

  Thus, by using the drying apparatus of the present invention, it is possible to suppress deformation during drying of the extruded honeycomb formed body, and to prevent problems such as cracks and wrinkles on the outer peripheral wall.

In the first aspect of the invention, the central part of the honeycomb formed body is a center point in the radial cross section of the honeycomb formed body and a portion of the cell wall in the vicinity of the center point indicating a temperature equivalent to the center point. is there.
The curing start temperature of the binder is a temperature at which the binder in the honeycomb formed body starts to be cured, and is a temperature at which the honeycomb formed body starts to gel.

In the first step, when the temperature of the central portion of the honeycomb formed body reaches the curing start temperature of the binder, the temperature difference between the central portion and the outer peripheral wall is 5 ° C. or less. Preferably, the microwave output is set (claim 2).
In this case, it is possible to reduce the stress caused by the difference in drying shrinkage between the central portion and the outer peripheral wall, and to further suppress the deformation of the honeycomb formed body.

In the first step, it is preferable that the microwave output per unit mass of the honeycomb formed body is 20 W / g.
In this case, the state in which the honeycomb formed body contains a large amount of moisture can be reliably shortened, and deformation of the honeycomb formed body during drying can be further suppressed.

Moreover, in the said drying process, it is preferable to make the said microwave output small in steps for every said step (Claim 4).
In this case, the thermal shock to the honeycomb formed body in the drying step can be reduced, and the occurrence of cracks and the like can be prevented.

In the drying step, the microwave output of each step is preferably set so that a temperature difference between the central portion of the honeycomb formed body and the outer peripheral wall is 5 ° C. or less. ).
In this case, in the whole drying process, stress generated by the drying shrinkage difference between the central portion and the outer peripheral wall can be reduced, and deformation of the honeycomb formed body can be further suppressed.

The thickness of the cell wall of the honeycomb formed body after the drying step is preferably 70 μm or less.
That is, the effect of suppressing the deformation of the cell wall during drying can be more effectively exhibited by using the manufacturing method of the present invention for the honeycomb formed body having the thin cell wall.

Moreover, in the said drying process, it is preferable to make the said microwave output between each step constant.
In this case, it is easy to control the microwave output, and the drying process can proceed smoothly.
It should be noted that the microwave output between each step can be changed without making it constant. However, when the microwave output is reduced step by step for each step, it is necessary to set the microwave output within a range smaller than the microwave output of the immediately preceding step.

In the drying step, it is preferable to obtain in advance the total output of microwaves necessary for drying the honeycomb formed body, and set the microwave output of each step within the total output range based on this. .
In this case, overdrying of the honeycomb formed body in the drying step can be prevented.

In the second invention, the microwave generator in the first zone is configured such that the temperature of the central portion of the honeycomb formed body reaches the curing start temperature of the binder and the central portion and the outer peripheral wall. It is preferable that the microwave output is set so that the temperature difference with respect to 5 ° C. or less is set.
In this case, it is possible to reduce the stress caused by the difference in drying shrinkage between the central portion and the outer peripheral wall, and to further suppress the deformation of the honeycomb formed body.

The microwave generator in the first zone is preferably configured so that the microwave output per unit mass of the honeycomb formed body is set to 20 W / g.
In this case, the state in which the honeycomb formed body contains a large amount of moisture can be reliably shortened, and deformation of the honeycomb formed body during drying can be further suppressed.

Moreover, it is preferable that the said microwave generator of the said drying tank is comprised so that the said microwave output may be set small in steps for every said zone (Claim 10).
In this case, the thermal shock to the honeycomb formed body in the drying step can be reduced, and the occurrence of cracks and the like can be prevented.

In the microwave generator of the drying tank, the microwave output of each zone is set so that a temperature difference between the central portion of the honeycomb formed body and the outer peripheral wall is 5 ° C. or less. It is preferable to be configured as described above (claim 11).
In this case, in the whole drying process, stress generated by the drying shrinkage difference between the central portion and the outer peripheral wall can be reduced, and deformation of the honeycomb formed body can be further suppressed.

A method for manufacturing a honeycomb structure according to an embodiment of the present invention and a drying apparatus used therefor will be described.
In this example, as shown in FIG. 1, a honeycomb structure made of cordierite ceramic having a large number of rectangular cells 12 surrounded by a honeycomb-shaped cell wall 11 and a cylindrical outer peripheral wall 13 covering the outer peripheral side surface. 1 is a method of manufacturing 1. The honeycomb structure 1 of the present example has a substantially cylindrical shape. Note that the overall shape of the honeycomb structure 1, the shape of the cells 12, and the like can be changed according to the application.
Further, as shown in FIG. 5, the center portion 101 of the honeycomb molded body 10 to be described later is a central point in the radial cross section of the honeycomb molded body 10 and a cell wall 11 in the vicinity of the central point indicating a temperature equivalent to the central point. It is a part of.

And the manufacturing method of the honeycomb structure 1 of this example extrude-molds the ceramic material containing at least a cordierite raw material, water, and a binder, cut | disconnects to predetermined length, and the honeycomb molded body 10 (refer FIG. 1). A forming step for forming the honeycomb structure, a drying step for drying the honeycomb formed body 10 by irradiation with microwaves, and a firing step for firing the honeycomb formed body 10 to obtain the honeycomb structure 1 are performed.
In the drying process, the drying process is divided into a plurality of steps, and the first step S1 is a period from the start of drying until the temperature of the central portion 101 of the honeycomb formed body 10 reaches at least the curing start temperature of the binder. The microwave output irradiated to the honeycomb formed body 10 is set to be higher than the microwave output in the subsequent steps.
This will be described in detail below.

<Molding process>
First, a ceramic material that becomes cordierite ceramic after firing is prepared. Specifically, 19.5% by weight of water and 4.5% by weight of binder are added to 100% by weight of the cordierite raw material and kneaded to produce a ceramic material. The cordierite raw material, which is a raw material powder, includes talc of 38 to 40% by weight, kaolin so that the final composition is cordierite (2MgO · 2Al ₂ O ₃ · 5SiO ₂ ). A mixture of 46 to 48% by weight and alumina of 12 to 16% by weight was used. Moreover, methylcellulose was used as the binder.

Next, the ceramic material is extruded from a honeycomb mold using an extruder (not shown). Then, the honeycomb formed body 10 is formed by sequentially cutting to a predetermined length.
The molded honeycomb body 10 after molding had a mass of 1430 g, a specific gravity of about 2.0, and a moisture content of 19.5%.

<Drying process>
Next, the obtained honeycomb formed body 10 is dried using the drying apparatus 2 shown in FIG.
As shown in the figure, the drying device 2 of the present example includes a drying tank 21 that accommodates the honeycomb formed body 10, a conveyor 22 that continuously conveys the honeycomb formed body 10 in the drying tank 21, and a drying tank 21. And a microwave generator 23 for irradiating a plurality of microwaves arranged in the conveying direction of the honeycomb formed body 10.

The drying device 2 has a drying tank 21 formed so as to surround the conveyor 22. The drying tank 21 is provided with a carry-in port 211 and a carry-out port 212 for allowing the honeycomb formed body 10 placed on the feed conveyor 22 to pass through the feed conveyor 22.
In addition, a total of seven microwave generators 23 are provided at equal intervals on the upper wall surface of the drying tank 21. The microwave generator 23 is connected to a control device (not shown), and is configured to control and irradiate a microwave output based on a control signal from the control device.

Moreover, the drying tank 21 of this example is divided | segmented into the some zone (1st zone Z1, 2nd zone Z2, and 3rd zone Z3) in the conveyance direction of the honeycomb molded object 10, as shown in FIG.
Three microwave generators 23 are provided in the first zone Z1 in which the honeycomb formed body 10 is first conveyed. In the microwave generator 23 of the first zone Z1, the honeycomb molded body 10 passes through the first zone Z1, and the temperature of the central portion 101 of the honeycomb molded body 10 is at least the binder curing start temperature (in this example, about The microwave output is set to reach 60 ° C. In this example, the microwave output of each microwave generator 23 in the first zone Z1 is 28.6 kW. That is, it was set to 20 W / g in terms of unit mass of the honeycomb formed body 10 before drying.

In addition, two microwave generators 23 are provided in each of the second zone Z2 and the third zone Z3. The microwave outputs of the microwave generators 23 in the second zone Z2 and the third zone Z3 were 20 kW (14 W / g) and 14 kW (9.8 W / g), respectively.
That is, the microwave output of each microwave generator 23 of this example was set so that the first zone Z1 was the highest and decreased stepwise for each zone.

  In addition, the area | region of each zone and the number of zones can be changed with the selection number of the said seven microwave generators 23, and it adjusts so that it may become optimal according to the specification of the honeycomb molded object 10 which should be processed. Can do. Of course, the number of the microwave generators 23 arranged in the drying tank 21 can be changed or the arrangement position can be adjusted.

  In drying the extruded honeycomb formed body 10 using the drying apparatus 2 having such a configuration, as shown in FIG. 2, first, the honeycomb formed body 10 is placed on the transport tray 24, and this is transported to the transport conveyor. 22 is mounted. Thereby, the honeycomb formed body 10 is carried into the drying tank 21 from the carry-in port 211. The honeycomb molded body 10 carried into the drying tank 21 passes through the first zone Z1, the second zone Z2, and the third zone Z3 by the conveyor 22 and is conveyed to the carry-out port 212. It is dried by the microwave irradiated from the generator 23. Thereafter, the honeycomb formed body 10 is unloaded from the unloading port 212 in the drying tank 21. Thereby, the honeycomb formed body 10 is dried.

  That is, the drying process of this example can be divided into three steps. A first step S1 in which the honeycomb formed body 10 passes through the first zone Z1, a second step S2 through which the second zone Z2 passes, and a third step S3 through which the third zone Z3 passes. In the first step S1, the honeycomb formed body 10 is dried at a microwave output of 20 W / g, in the second step S2, is dried at a microwave output of 14 W / g, and in the third step S3, the microwave output is 9.8 W. Dry at / g. The transport time from the carry-in port 211 to the carry-out port 212 of each honeycomb formed body 10 was set to 0.5 hour. FIG. 3 shows the relationship between the microwave output (W / g) and time (h) in each step.

<Baking process>
Next, the dried honeycomb formed body 10 is cooled. Baking is performed under conditions of a maximum temperature of 1380 ° C. and a baking time of 72 hours.
Thus, the honeycomb structure 1 of FIG. 1 is obtained.

Next, in order to show the effectiveness of the manufacturing method of the honeycomb structure 1 of the present example, the following evaluation was performed.
First, the honeycomb formed body 10 having the same size as that of the present embodiment is formed. At this time, the honeycomb formed body 10 is formed so that the cell wall 11 after drying has a desired thickness. The thickness of the cell wall 11 after drying was four types of 69 μm, 79 μm, 83 μm, and 88 μm, and six specimens were prepared for each condition. Next, the honeycomb formed body 10 is dried with the microwave output pattern as shown in FIG. Then, the dried honeycomb formed body 10 was visually observed for occurrence of defects such as cracks and wrinkles in the outer peripheral wall 13.
As a comparative example, as shown in FIG. 4, drying was performed with the microwave output constant as in the prior art, and the occurrence of defects such as cracks and wrinkles in the outer peripheral wall 13 was evaluated in the same manner as in the example.

Table 1 shows the results of occurrence of defects under each condition.
As can be seen from the table, the occurrence of defects was not confirmed in both the example and the comparative example under the condition where the thickness of the cell wall 11 was 79 μm or more. However, under the condition of the cell wall 11 having a thickness of 69 μm, no defect was confirmed in the example, but the defect was confirmed in all six test specimens of the comparative examples.

  Thus, it can be seen that the example can prevent the occurrence of defects such as cracks and wrinkles in the outer peripheral wall 13 even in the honeycomb molded body 10 in which the thickness of the cell wall 11 after drying is smaller than that of the comparative example. In particular, the above effect can be exhibited under the condition that the thickness of the cell wall 11 is 70 μm or less.

Next, the temperature of the honeycomb formed body 10 at the time of drying was evaluated under the condition of a thickness of 69 μm of the cell wall 11 in which a difference was found between the example and the comparative example.
First, a fiber thermometer is attached to the formed honeycomb formed body 10. As shown in FIG. 5, the fiber thermometers were installed in a total of four locations, two at the center 101 of the honeycomb molded body 10 (A1, A2) and two at the outer peripheral wall 13 (B1, B2). Next, the honeycomb formed body 10 is dried while measuring the temperature of each part with a fiber thermometer. Then, the maximum temperature difference between the central portion 101 and the outer peripheral portion 13 was obtained as an internal / external temperature difference ΔT. Further, the time from the start of drying to the binder curing start point T1 at which the binder contained in the honeycomb formed body 10 starts curing was measured.

In the comparative example, as shown in FIG. 4, the time from the start of drying to the binder curing start point T1 was 0.3 hours. The internal / external temperature difference ΔT at the binder curing start point T1 was about 14 ° C.
On the other hand, in the example, as shown in FIG. 3, the time from the start of drying to the binder curing start point T1 was 0.2 hours. The internal / external temperature difference ΔT at the binder curing start point T1 was about 4 ° C.

  Thus, in an Example, it turns out that the time from drying start to binder hardening start point T1 is shortened compared with the comparative example. It can also be seen that the internal / external temperature difference ΔT at the binder curing start point T1 is also small.

Next, based on the above results, the operational effects in the method for manufacturing the honeycomb structure 1 of the present example will be described.
In the method for manufacturing the honeycomb structure 1 of the present example, the drying process is divided into a plurality of steps. The first step is from the start of drying until the temperature of the central portion 101 of the honeycomb formed body 10 reaches at least the curing start temperature of the binder. Let S1. And in this 1st step S1, the microwave output irradiated to the honeycomb molded object 10 is set higher than the microwave output of a subsequent step (2nd step S2, 3rd step S3).

  That is, the honeycomb formed body 10 immediately after the forming process still contains a lot of moisture and is in a state of being easily deformed. In this example, the microwave output of the first step S1, which is the first step among the plurality of steps of the drying process, is made highest. Therefore, the temperature of the honeycomb formed body 10 can be raised early, and moisture contained in the honeycomb formed body 10 can be removed at the earliest possible stage of the drying process. And time until the temperature of the center part 101 of the honeycomb molded object 10 reaches the hardening start temperature of a binder can be shortened. That is, the time of the first step S1 can be shortened.

  Thereby, when the time of the whole drying process is made constant, the time of 1st step S1 which occupies for the whole drying process can be shortened. In addition, the honeycomb formed body 10 in the drying process can shorten the state of being easily deformed and containing a large amount of moisture. Therefore, deformation of the cell wall 11 at the time of drying can be suppressed, and occurrence of problems such as cracking and wrinkling of the outer peripheral wall 13 can be prevented.

  In the first step S1 of this example, the microwave output per unit mass of the honeycomb formed body 10 is set to 20 W / g. Therefore, the state in which the honeycomb formed body 10 contains a large amount of moisture can be reliably shortened, and deformation of the honeycomb formed body 10 during drying can be further suppressed.

  Further, in the first step S1, when the temperature of the central portion 101 of the honeycomb molded body 10 reaches the binder curing start temperature (binder curing start point T1), the temperature difference between the central portion 101 and the outer peripheral wall 13 is 5. The microwave output is set so as to be below ℃. Therefore, the stress produced by the drying shrinkage difference between the central portion 101 and the outer peripheral wall 13 can be reduced, and deformation of the honeycomb formed body 10 during drying can be further suppressed.

In the drying process, the microwave output is reduced step by step for each step. Therefore, the thermal shock to the honeycomb formed body 10 in the drying process can be reduced, and the occurrence of cracks and the like can be prevented. Moreover, overdrying of the honeycomb formed body 10 can also be prevented.
In the drying process, the microwave output between each step is constant. Therefore, it is easy to control the microwave output, and the drying process can proceed smoothly.

  Moreover, when the thickness of the cell wall 11 of the honeycomb formed body 10 after the drying step is 70 μm or less, the effect of suppressing the deformation of the cell wall 11 at the time of drying can be more effectively exhibited.

  As described above, according to the method for manufacturing a honeycomb structure of the present example, deformation of the extruded honeycomb formed body during drying can be suppressed, and problems such as cracks and wrinkles on the outer peripheral wall can be prevented.

An explanatory view showing a honeycomb structure (honeycomb fabrication object) in an example. Explanatory drawing which shows the structure of the drying apparatus in an Example. Explanatory drawing which showed the microwave output pattern in an Example. Explanatory drawing which showed the microwave output pattern in a comparative example. Explanatory drawing which showed the attachment place of the fiber thermometer in an Example and a comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Honeycomb structure 10 Honeycomb molded object 101 Center part 11 Cell wall 12 Cell 13 Perimeter wall 2 Drying device 21 Drying tank 22 Conveyor 23 Microwave generator

Claims (11)

In a method of manufacturing a honeycomb structure made of cordierite ceramic having a large number of cells surrounded by a honeycomb-shaped cell wall and a cylindrical outer peripheral wall covering the outer peripheral side surface,
A molding step of forming a honeycomb formed body by extruding a ceramic material containing at least a cordierite raw material, water, and a binder and cutting it to a predetermined length;
A drying step of drying the honeycomb formed body by irradiation with microwaves;
A firing step of firing the honeycomb formed body to obtain the honeycomb structure,
In the drying step, the drying step is divided into a plurality of steps, and the first step is from the start of drying until the temperature of the central portion of the honeycomb formed body reaches at least the curing start temperature of the binder. A method for manufacturing a honeycomb structured body, characterized in that a microwave output applied to the honeycomb formed body is set higher than a microwave output in a subsequent step.   In Claim 1, in the said 1st step, when the temperature of the said center part of the said honeycomb molded object reaches the hardening start temperature of the said binder, the temperature difference of the said center part and the said outer peripheral wall is 5 degrees C or less. Thus, the manufacturing method of the honeycomb structure characterized by setting the said microwave output.   3. The method for manufacturing a honeycomb structure according to claim 1, wherein in the first step, the microwave output per unit mass of the honeycomb formed body is set to 20 W / g.   The method for manufacturing a honeycomb structure according to any one of claims 1 to 3, wherein in the drying step, the microwave output is reduced stepwise for each step.   5. The microwave output according to claim 1, wherein, in the drying step, the microwave output of each step is set so that a temperature difference between the central portion of the honeycomb formed body and the outer peripheral wall is 5 ° C. or less. A method for manufacturing a honeycomb structure, characterized in that   The method for manufacturing a honeycomb structure according to any one of claims 1 to 5, wherein a thickness of the cell wall of the honeycomb formed body after the drying step is 70 µm or less. In manufacturing a cordierite ceramic honeycomb structure having a large number of cells surrounded by a honeycomb-shaped cell wall and a cylindrical outer peripheral wall covering the outer peripheral side surface, at least a cordierite raw material, water, and a binder are used. In a drying apparatus for extruding a ceramic material containing and drying a honeycomb formed body cut into a predetermined length,
The drying apparatus includes a drying tank that accommodates the honeycomb formed body, a transport conveyor that continuously transports the honeycomb formed body in the drying tank, and a plurality of the drying apparatuses arranged in the transport direction of the honeycomb formed body in the drying tank. A microwave generator for irradiating the installed microwave,
The drying tank is divided into a plurality of zones, and the microwave generator in the first zone to which the honeycomb formed body is first conveyed is the honeycomb generator while the honeycomb formed body passes through the first zone. The microwave output is configured so that the temperature of the central portion of the molded body reaches at least the curing start temperature of the binder, and the microwave output is higher than other zones. Drying equipment to do.   8. The microwave generator according to claim 7, wherein the temperature of the central portion and the outer peripheral wall is reached when the temperature of the central portion of the honeycomb formed body reaches the curing start temperature of the binder. The drying apparatus, wherein the microwave output is set so that the difference is 5 ° C. or less.   In Claim 7 or 8, the said microwave generator of the said 1st zone is comprised so that the said microwave output per unit mass of the said honeycomb molded object may be set to 20 W / g. Drying equipment.   The drying apparatus according to any one of claims 7 to 9, wherein the microwave generator of the drying tank is configured so that the microwave output is set to be small step by step for each of the zones. apparatus.   In any one of Claims 7-10, the said microwave generator of the said drying tank WHEREIN: Said each so that the temperature difference of the said center part of the said honeycomb molded object and the said outer peripheral wall may be 5 degrees C or less. A drying apparatus configured to set the microwave output of the zone.

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