Method for dielectric drying of a ceramic shaped body, dielectric drying device and method for manufacturing a ceramic structure

Abstract

A dielectric drying method of a ceramic formed body (10) is provided, in which a plurality of ceramic formed bodies (10) loaded side by side on an upper surface of a drying support table (20) in an arrangement direction (Y) perpendicular to a conveyance direction (X) are conveyed to an electrode gap between an upper electrode (130) and a lower electrode (140), and dried by applying high frequency to the electrode gap. The conveyance of the drying support table (20) is performed by a conveyor (120) having one or more conveyance belts (121) that support a portion of the drying support table (20) in the arrangement direction Y. In addition, one or more electric field adjusting members (150) are arranged below the drying support table (20) that is not supported by the conveyance belt (121).

Description

Technical Field

[0001] This invention relates to a dielectric drying method and apparatus for ceramic molded bodies, as well as a method for manufacturing ceramic structures. Background Technology

[0002] Ceramic structures are used in a variety of applications. For example, honeycomb-shaped ceramic structures with partitions forming multiple pores extending from a first end face to a second end face are widely used in catalyst supports, diesel particulate filters (DPF), gasoline particulate filters (GPF), and various other filters.

[0003] Ceramic structures are manufactured by molding clay containing ceramic raw materials into a ceramic molded body, then drying and firing the ceramic molded body. It should be noted that in this specification, the state after extrusion molding and before drying is referred to as the ceramic molded body, and the state after firing is referred to as the ceramic structure.

[0004] Dielectric drying is a common method for drying ceramic molded bodies. In dielectric drying, a ceramic molded body is placed between a pair of electrodes. High-frequency energy generated by energizing the electrodes causes molecular motion of water dipoles within the ceramic molded body, and the ceramic molded body is dried through frictional heat. It should be noted that in this specification, "dielectric drying" refers to high-frequency dielectric drying (frequency approximately 1–100 MHz) where the object to be dried is placed between a pair of electrodes, and does not include microwave drying (frequency approximately 300 mHz–300 GHz) where electromagnetic waves are radiated from an oscillator to the object to be dried.

[0005] However, in dielectric drying, it is difficult to dry ceramic molded bodies uniformly, resulting in problems such as cracks during firing and uneven dimensions of the ceramic structure. Therefore, various studies have been conducted on dielectric drying.

[0006] For example, Patent Document 1 proposes the following method: if a honeycomb molded body (ceramic molded body) is placed on a drying support table and dielectric drying is performed, a high moisture area will be generated near the upper and lower end faces. Therefore, a drying support table with a certain area of ​​the part in contact with the lower end face of the opening of the honeycomb molded body is set as a porous plate is used for drying.

[0007] In addition, in Patent Document 2, in order to suppress the drying deviation of the honeycomb molded body (ceramic molded body) continuously conveyed by the conveyor, the following method is proposed: the electrodes provided above the upper end face and below the lower end face of the opening of the honeycomb molded body are divided into multiple corresponding positions, so that the honeycomb molded body is moved intermittently every pair of electrode units for drying.

[0008] Furthermore, in Patent Document 3, in order to dry the honeycomb molded body uniformly, a method is proposed to dry the honeycomb molded body while rotating it around the long axis between a pair of electrodes.

[0009] On the other hand, although it involves a high-frequency defrosting device for frozen food, Patent Document 4 also mentions a technique for suppressing uneven defrosting by changing the area of ​​the electrodes according to the defrosting state of the frozen food.

[0010] Existing technical documents

[0011] Patent documents

[0012] Patent Document 1: Japanese Patent Publication No. 60-37382

[0013] Patent Document 2: Japanese Patent Application Publication No. 5-105501

[0014] Patent Document 3: Japanese Patent Application Publication No. 6-298563

[0015] Patent Document 4: Japanese Patent No. 4630189 Summary of the Invention

[0016] The problem that the invention aims to solve

[0017] Dielectric drying of ceramic molded bodies is performed as follows: multiple (e.g., 2 to 5) ceramic molded bodies are placed side-by-side on the upper surface of a drying support table along an arrangement direction Y perpendicular to the conveying direction X. The drying support table is continuously conveyed between the upper and lower electrodes using a conveyor, and a high frequency is applied. The conveyor has one or more conveyor belts that support a portion of the drying support table in the arrangement direction Y.

[0018] However, while the method described in Patent Document 1 can suppress deviations in the drying state of the upper and lower parts of a single ceramic molded body placed on a drying support table, it is difficult to suppress deviations in the drying state along the alignment direction Y (the width direction of the drying support table). In fact, along the alignment direction Y, the electric field strength locally increases in the portion supported by the conveyor belt, tending to increase drying shrinkage. On the other hand, the electric field strength decreases in the portion not supported by the conveyor belt, tending to decrease drying shrinkage. As a result, the drying state deviates depending on the position of the ceramic molded bodies placed side-by-side along the alignment direction Y.

[0019] Furthermore, the method described in Patent Document 2 aims to suppress the deviation of the drying state of the ceramic molded body placed on the multiple drying support tables in the conveying direction X, but does not suppress the deviation of the drying state of the multiple ceramic molded bodies placed on the drying support tables in the arrangement direction Y.

[0020] Furthermore, the method described in Patent Document 3 is used in a batch furnace, and therefore it is difficult to apply this method in a continuous furnace where mass production is the premise.

[0021] The present invention was made to solve the problems mentioned above, and its object is to provide a dielectric drying method and a dielectric drying apparatus for ceramic molded bodies that can suppress deviations in the drying state of multiple ceramic molded bodies placed on a drying support stage in the arrangement direction Y perpendicular to the conveying direction X.

[0022] In addition, the present invention aims to provide a method for manufacturing ceramic structures that can achieve uniform shape.

[0023] Methods for solving problems

[0024] The inventors conducted in-depth research on the dielectric drying of multiple ceramic molded bodies arranged side by side on the upper surface of a drying support table along an arrangement direction Y perpendicular to the conveying direction X. As a result, they found that by arranging one or more electric field adjustment components in the arrangement direction Y below the drying support table which is not supported by a conveyor belt, the above-mentioned problem can be solved, thus completing the present invention.

[0025] That is, the present invention is a dielectric drying method for ceramic molded bodies, wherein multiple ceramic molded bodies placed side by side on the upper surface of a drying support platform along an arrangement direction Y perpendicular to the conveying direction X are conveyed to the space between upper and lower electrodes, and dried by applying a high frequency to the space between the electrodes. The conveying of the drying support platform is carried out by a conveyor having one or more conveyor belts, the one or more conveyor belts supporting a portion of the drying support platform in the arrangement direction Y, and one or more electric field adjustment components are arranged below the portion of the drying support platform not supported by the conveyor belts.

[0026] In addition, the present invention is a method for manufacturing a ceramic structure, which includes the above-mentioned dielectric drying method for ceramic molded bodies.

[0027] Furthermore, the present invention provides a dielectric drying apparatus for ceramic molded bodies, comprising an upper electrode, a lower electrode, a conveyor, and one or more electric field adjustment components; the conveyor has one or more conveyor belts supporting a portion of a drying support platform in the arrangement direction Y, and is capable of conveying the plurality of ceramic molded bodies between the electrodes of the upper electrode and the lower electrode via the conveyor belts; the drying support platform is used to place the plurality of ceramic molded bodies side by side in the arrangement direction Y perpendicular to the conveying direction X; the one or more electric field adjustment components are disposed below the drying support platform which is not supported by the conveyor belts.

[0028] Invention Effects

[0029] According to the present invention, a dielectric drying method and a dielectric drying apparatus for ceramic molded bodies can be provided, which can suppress deviations in the drying state of multiple ceramic molded bodies placed on a drying support table in the arrangement direction Y perpendicular to the conveying direction X.

[0030] Furthermore, according to the present invention, a method for manufacturing a ceramic structure capable of achieving uniform shape can be provided. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the dielectric drying apparatus in the conveying direction X of a dielectric drying method suitable for use in embodiments of the present invention for ceramic molded bodies.

[0032] Figure 2 yes Figure 1 A schematic diagram of the arrangement direction Y of the dielectric drying device.

[0033] Figure 3 This is a schematic diagram of the arrangement direction Y of another dielectric drying device.

[0034] Figure 4 Is Figure 2 A schematic diagram of a dielectric drying apparatus equipped with another electric field adjustment component.

[0035] Figure 5 It is a graph showing the relationship between the position of the ceramic molded body in the Y-direction and the heating amount distribution ratio. Detailed Implementation

[0036] The embodiments of the present invention will now be described in detail. It should be understood that the present invention is not limited to the following embodiments. Any changes, modifications, or other alterations to the following embodiments based on ordinary knowledge of those skilled in the art, without departing from the spirit of the present invention, also fall within the scope of the present invention.

[0037] (1) Dielectric drying method and dielectric drying device for ceramic molded bodies

[0038] The dielectric drying method for ceramic molded bodies according to embodiments of the present invention is implemented in the following manner: multiple ceramic molded bodies arranged side by side in the arrangement direction Y perpendicular to the conveying direction X are conveyed to the space between the upper electrode and the lower electrode (between electrodes), and dried by applying a high frequency to the space between electrodes.

[0039] A schematic diagram of the conveying direction X of a dielectric drying apparatus suitable for a dielectric drying method for this ceramic molded body is shown in the figure. Figure 1 Additionally, a schematic diagram of the dielectric drying apparatus arranged in the Y direction is shown in [the diagram]. Figure 2 .

[0040] like Figure 1 as well as Figure 2 As shown, the dielectric drying apparatus 100 includes an upper electrode 130, a lower electrode 140, a conveyor 120, and one or more electric field adjustment components 150. The conveyor 120 has one or more conveyor belts 121 supporting a portion of the drying support platform 20 in the arrangement direction Y. Multiple ceramic molded bodies 10 can be conveyed between the electrodes of the upper electrode 130 and the lower electrode 140 using the conveyor belts 121. The drying support platform 20 is used to hold multiple ceramic molded bodies 10 side-by-side in the arrangement direction Y, which is perpendicular to the conveying direction X. One or more electric field adjustment components 150 are disposed below the drying support platform 20, which is not supported by the conveyor belts 121. The upper electrode 130 is disposed above the dielectric drying oven 110, and the lower electrode 140 is disposed below the dielectric drying oven 110. Furthermore, the dielectric drying apparatus 100 may also incorporate known structures (e.g., a ventilated drying device) without hindering the effects of the present invention.

[0041] Multiple ceramic molded bodies 10 placed on the drying support platform 20 are conveyed by the conveyor belt 121 of the conveyor 120 to the space between the upper electrode 130 and the lower electrode 140 of the dielectric drying oven 110. At this time, the high-frequency energy generated by energizing the upper electrode 130 and the lower electrode 140 can cause the water dipoles in the ceramic molded body 10 to undergo molecular motion, and the ceramic molded body 10 is dried by frictional heat.

[0042] The conveyor belt 121 of the conveyor 120 varies depending on the type of conveyor 120, but is shorter than the length of the drying support platform 20 in the Y direction, supporting a portion of the drying support platform 20 in the Y direction. Therefore, a space is created beneath the drying support platform 20 that is not supported by the conveyor belt 121. For example, as... Figure 2 As shown, the conveyor belts 121 of the conveyor 120 can be two conveyor belts 121 supporting the drying support platform 20 near both ends in the arrangement direction Y. Alternatively, as... Figure 3 As shown, the conveyor belt 121 of the conveyor 120 can be a single conveyor belt 121 supporting the central portion of the drying support platform 20 in the Y-direction. It should be noted that the number and position of the conveyor belts 121 are not limited to... Figure 2 And the specific example shown in 3.

[0043] If the conveyor belt 121 described above is used to transport the multiple ceramic molded bodies 10 placed on the drying support table 20 between the electrodes of the upper electrode 130 and the lower electrode 140, the electric field strength of the ceramic molded body 10b placed on the drying support table 20 that is not supported by the conveyor belt 121 will be less than the electric field strength of the ceramic molded body 10a placed on the drying support table 20 that is supported by the conveyor belt 121, and the drying state of the multiple ceramic molded bodies 10 will deviate in the arrangement direction Y.

[0044] Therefore, in embodiments of the present invention, one or more electric field adjustment components 150 are arranged in the space below the drying support table 20 which is not supported by the conveyor belt 121. By arranging the electric field adjustment components 150 in such a position, the electric field strength in the alignment direction Y is made approximately the same, which can suppress deviations in the drying state of the multiple ceramic molded bodies 10 in the alignment direction Y.

[0045] As for the electric field adjustment component 150, there are no particular limitations as long as it can adjust the electric field strength. Preferably, it is a sheet material with a thickness of 20% or more but less than 100% of the thickness of the conveyor belt 121. With such a sheet material, it can be easily placed in the space below the drying support table 20, which is not supported by the conveyor belt 121. It should be noted that the thickness of the conveyor belt 121 is not particularly limited, for example, it is 10 to 50 mm.

[0046] like Figure 2 As shown, multiple electric field adjustment components 150 can be arranged in a space partition below the drying support table 20 that is not supported by the conveyor belt 121, but as... Figure 4 As shown, an electric field adjustment component 150 can also be arranged in this space. When the electric field adjustment components 150 are arranged in a segmented manner, the length of each electric field adjustment component 150 in the arrangement direction Y is preferably the same as or greater than the length of the ceramic molded body 10 in the arrangement direction Y.

[0047] Preferably, the electric field adjustment component 150 is disposed in the region corresponding to the position of the upper ceramic molded body 10b in the vertical direction Z (the space below the drying support stage 20). By disposing the electric field adjustment component 150 in this way, deviations in the electric field strength in the alignment direction Y can be stably suppressed.

[0048] The electric field adjustment component 150 is preferably constructed from one or more materials selected from conductors and insulators with a relative permittivity of 1.0 or higher. By constructing the electric field adjustment component 150 from a conductor, it functions as part of the lower electrode 140, and the distance between electrodes is shortened in the region where the electric field adjustment component 150 is located. As a result, the electric field strength increases in the region where the electric field adjustment component 150 is located, suppressing deviations in the electric field strength along the alignment direction Y. Furthermore, by constructing the electric field adjustment component 150 from an insulator with a relative permittivity of 1.0 or higher, an electric current can be induced in the region where the electric field adjustment component 150 is located. As a result, the electric field strength increases in this region, suppressing deviations in the electric field strength along the alignment direction Y. Furthermore, by constructing the electric field adjustment component 150 from a composite of a conductor and an insulator with a relative permittivity of 1.0 or higher, both of the aforementioned functions based on the conductor and the insulator can be obtained. Therefore, the electric field strength in the region where the electric field adjustment component 150 is disposed increases, and deviations in the electric field strength in the alignment direction Y can be suppressed.

[0049] Examples of the conductors and insulators constituting the electric field adjustment component 150 include metals, ceramics, and resins. Two or more of these materials can be used individually or in combination. By using such materials, the electric field adjustment component 150 can be easily manufactured.

[0050] The preferred dielectric drying apparatus 100 further includes a drive mechanism capable of moving the position of the electric field adjustment member 150. By providing such a drive mechanism, the position of the electric field adjustment member 150 can be moved according to the drying state of the ceramic molded body 10, thereby further suppressing deviations in the drying state of the multiple ceramic molded bodies 10 in the alignment direction Y. Specifically, the drying state of the ceramic molded body 10 after dielectric drying is measured, and based on this measurement result, the position of the electric field adjustment member 150 (e.g., one or more positions in the conveying direction X, alignment direction Y, and vertical direction Z) is moved by the drive mechanism, thereby fine-tuning the electric field strength in the area where the electric field adjustment member 150 is located.

[0051] As a drive mechanism, there are no particular limitations as long as the position of the electric field adjustment component 150 can be adjusted; for example, known components such as motors and pneumatic lifters can be used. These drive mechanisms can be connected directly to the electric field adjustment component 150 or indirectly via connecting components.

[0052] The connection position of the drive mechanism in the electric field adjustment component 150 is not particularly limited as long as it does not obstruct dielectric drying. For example, the drive mechanism can be connected to the side of the electric field adjustment component 150.

[0053] The number of ceramic molded bodies 10 placed on the drying support table 20 can be adjusted appropriately according to the size of the drying support table 20, preferably 2 to 5, more preferably 3 to 5.

[0054] The size of the plurality of ceramic molded bodies 10 placed on the drying support table 20 is not particularly limited, but preferably they are approximately the same length in the vertical direction Z, and more preferably they are approximately the same length in all directions.

[0055] Both the upper electrode 130 and the lower electrode 140 can use known electrode plates. In addition, the upper electrode 130 can be processed into a desired shape using known methods.

[0056] Auxiliary electrodes can also be mounted on the upper end face 11a of multiple ceramic molded bodies 10. By mounting auxiliary electrodes, the electric field intensity on the upper end face 11a of the ceramic molded body 10, which is prone to becoming uneven during dielectric drying, can be homogenized. Therefore, the overall heating amount of the ceramic molded body 10 can be homogenized, thereby reducing uneven drying.

[0057] The material used as the auxiliary electrode is not particularly limited, but it is preferable to have a conductivity higher than that of the ceramic molded body 10. Such conductivity ensures sufficient functionality as an auxiliary electrode. Examples of materials suitable for the auxiliary electrode include aluminum, copper, aluminum alloys, copper alloys, and graphite. These can be used individually or in combination of two or more.

[0058] As an auxiliary electrode, a porous plate can be used, for example.

[0059] In this specification, "perforated plate" refers to a plate with openings.

[0060] The porosity of the porous plate is not particularly limited, but is preferably 20-90%, more preferably 40-80%. By controlling the porosity within such a range, the electric field intensity on the upper end surface 11a of the ceramic molded body 10, which is prone to becoming uneven during dielectric drying, can be homogenized. Therefore, the overall heating amount of the ceramic molded body 10 can be homogenized, thereby reducing uneven drying.

[0061] In this specification, "open area ratio of the perforated plate" refers to the ratio of the open area to the total area of ​​the surface of the perforated plate that contacts the upper end face 11a of the ceramic molded body 10.

[0062] The shape of the opening in the surface of the porous plate that contacts the upper end face 11a of the ceramic molded body 10 is not particularly limited, and can be set to various shapes such as circles, quadrilaterals, slits, etc.

[0063] The drying support stage 20 for holding the ceramic molded body 10 is not particularly limited, but it is preferable to have a perforated plate in the portion that contacts the lower end faces 11b of the plurality of ceramic molded bodies 10. By setting it in this way, water vapor can be easily removed from the lower end faces 11b of the ceramic molded body 10 during dielectric drying, so that the ceramic molded body 10 can be dried easily and uniformly.

[0064] There are no particular limitations on the materials used for perforated plates; examples include aluminum, copper, aluminum alloys, copper alloys, and graphite. These materials can be used individually or in combination of two or more.

[0065] The perforation ratio and shape of the perforated plate used for the drying support stage 20 are not particularly limited and can be set to be the same as those used for the auxiliary electrode.

[0066] The various conditions during dielectric drying (frequency, output power, heating time, etc.) can be appropriately set according to the object being dried (ceramic molded body 10) and the type of dielectric drying device 100. For example, the frequency during dielectric drying is preferably 10MHz to 100MHz.

[0067] The ceramic molded body 10 used for dielectric drying is not particularly limited, but its moisture content is preferably 1 to 60%, more preferably 5 to 55%, and even more preferably 10 to 50%. Ceramic molded bodies 10 with such a range of moisture content are prone to deviations in drying state during dielectric drying. Therefore, by using ceramic molded bodies 10 with such a range of moisture content, the effects of the present invention are more easily obtained.

[0068] In this specification, the moisture content of the ceramic molded body 10 refers to the moisture content measured by an infrared heating moisture meter.

[0069] The ceramic molded body 10 is not particularly limited, but is preferably a honeycomb molded body having partitions that divide and form a plurality of pores extending from the first end face to the second end face.

[0070] The shape of the pores in a honeycomb structure (the shape of the pores in a cross section orthogonal to the direction in which the pores extend) is not particularly limited. Examples of pore shapes include triangles, quadrilaterals, hexagons, octagons, circles, or combinations thereof.

[0071] The shape of the honeycomb molding body is not particularly limited, and examples include cylindrical, elliptical cylindrical, square, rectangular, triangular, pentagonal, hexagonal, octagonal and other polygonal prisms.

[0072] The ceramic molded body 10 can be obtained by molding a blank obtained by mixing a raw material composition containing ceramic raw materials and water.

[0073] As ceramic raw materials, there are no particular limitations; cordierite, cordierite, silicon carbide, silicon-silicon carbide composites, mullite, aluminum titanate, etc., can be used. They can be used alone or in combination of two or more. It should be noted that cordierite refers to ceramic raw materials formulated with a chemical composition ranging from 42-56% by mass of silicon dioxide, 30-45% by mass of aluminum oxide, and 12-16% by mass of magnesium oxide. Furthermore, cordierite is a raw material that has been fired to become cordierite.

[0074] In addition to ceramic raw materials and water, the raw material composition may also include a dispersion medium, a binding material (such as an organic binder, an inorganic binder, etc.), a pore-forming material, a surfactant, etc. The composition ratio of each raw material is not particularly limited, but is preferably a ratio that matches the structure and material of the ceramic molded body 10 to be produced.

[0075] As a method for mixing raw material compositions to form clay, a kneader or a vacuum ply mill can be used, for example. Furthermore, as a molding method for the ceramic molded body 10, known molding methods such as extrusion molding or injection molding can be used, for example. Specifically, when producing a honeycomb molded body as the ceramic molded body 10, extrusion molding can be performed using a die having the desired pore shape, septum wall (pore wall) thickness, and pore density. As the material of the die, a wear-resistant superhard alloy can be used.

[0076] In the dielectric drying method and dielectric drying apparatus 100 of the ceramic molded body 10 of the present invention, one or more electric field adjustment components 150 are arranged below the drying support table 20 which is not supported by the conveyor belt 121, thereby ensuring that the electric field strength in the alignment direction Y is the same. Therefore, deviations in the drying state of multiple ceramic molded bodies 10 in the alignment direction Y can be suppressed.

[0077] (2) Manufacturing method of ceramic structure

[0078] The method for manufacturing the ceramic structure according to the embodiments of the present invention includes the dielectric drying method of the ceramic molded body 10 described above.

[0079] It should be noted that, in the method for manufacturing the ceramic structure according to the embodiments of the present invention, the steps other than the above-mentioned dielectric drying method are not particularly limited, and steps known in the art can be applied. Specifically, the method for manufacturing the ceramic structure according to the embodiments of the present invention may further include the following firing step: after drying the ceramic molded body 10 by using the above-mentioned dielectric drying method to obtain a dried ceramic body, the dried ceramic body is fired to obtain the ceramic structure.

[0080] There are no particular limitations on the firing method for dried ceramic bodies; for example, firing in a firing furnace is sufficient. Furthermore, the firing furnace and firing conditions can be appropriately selected based on the shape and material of the honeycomb structure being produced. It should be noted that pre-firing can also remove organic substances such as binders before final firing.

[0081] The method for manufacturing a ceramic structure according to an embodiment of the present invention includes a dielectric drying method capable of suppressing deviations in the drying state of multiple ceramic molded bodies 10 in the arrangement direction Y, thereby enabling the ceramic structure to achieve uniform shape.

[0082] Example

[0083] The present invention will be described in more detail below through embodiments, but the present invention is not limited to these embodiments in any way.

[0084] <Example 1>

[0085] (Production of ceramic molded bodies)

[0086] A honeycomb molded body was fabricated as a ceramic molded body. First, a cordierite raw material, a mixture of alumina, kaolin, and talc as ceramic raw materials, was used. A binder containing an organic binder, a water-absorbing resin as a pore-forming material, and water as a dispersion medium were mixed with the cordierite raw material to prepare a raw material composition. This composition was then kneaded to obtain a blank. Next, the obtained blank was extruded to obtain a honeycomb molded body with a square cross-section having pores orthogonal to the pore extension direction. The outer diameter (diameter) of the honeycomb molded body was 140 mm, and the length (length in the pore extension direction) was 200 mm; the outer diameter was cylindrical. Furthermore, the moisture content of this honeycomb molded body was 40%. The moisture content and weight of the honeycomb molded body are averages of all honeycomb molded bodies produced.

[0087] (Dielectric drying of ceramic molded bodies)

[0088] Dielectric drying is performed using the ceramic molded body (honeycomb molded body) prepared above. Specifically, the following steps are followed.

[0089] Five ceramic molded bodies are arranged side-by-side along the Y-direction on the upper surface of a drying support stage (10 mm thick) having an aluminum porous plate (60% porosity, 2 mm thickness) in contact with the lower end face of the honeycomb molded body. An auxiliary electrode (an aluminum porous plate with 60% porosity and 2 mm thickness) is placed on the upper end face of each of the five ceramic molded bodies. A total of nine drying support stages, each containing five ceramic molded bodies, are prepared in this manner.

[0090] As a dielectric drying apparatus, a dielectric drying apparatus is used that has a conveyor with two conveyor belts (20 mm thick, 190 mm long in the Y direction) supporting the drying support table near both ends in the Y direction. Figure 2 Nine drying platforms, each supporting five honeycomb molded bodies, are mounted on the conveyor belt of the dielectric drying apparatus. Three electric field adjustment components (aluminum plates, 15mm thick, arranged in the Y direction with a length of 190mm) are positioned below the drying platforms not supported by the conveyor belt. Figure 2 Additionally, the distance between the auxiliary electrode and the upper electrode in the vertical direction is set to 100 mm.

[0091] Dielectric drying is carried out by rotating a conveyor belt in the X-direction and conveying the honeycomb molded body placed on the drying support platform into the dielectric drying oven. The dielectric drying conditions are set as follows: frequency 40.68 MHz (ISM band), output power 85.0 kW, and heating time 12 minutes.

[0092] <Comparative Example 1>

[0093] Except that no electric field adjustment component is provided under the drying support platform that is not supported by the conveyor belt, the dielectric drying of the honeycomb molded body is performed in the same manner as in Example 1.

[0094] (Calculation of heating amount)

[0095] First, the simulation of ceramic bodies placed side-by-side in the alignment direction Y is analyzed using the finite-difference time-domain (FDTD) method. In the simulation, the electric field intensity E at each lattice point within the ceramic body is determined.

[0096] Next, based on the obtained electric field strength E, the heating amount H at each grid point is calculated according to the following formula (1).

[0097] [Number 1]

[0098]

[0099] In equation (1), ω is the angular frequency (2π×40MHz), ε is the dielectric constant of the ceramic molded body, and tanδ is the dielectric loss tangent of the ceramic molded body.

[0100] Next, the heating amount H at the grid points in each ceramic molded body is summed to calculate the total heating amount of each ceramic molded body. The total heating amount of the five ceramic molded bodies from the left end to the right end in the arrangement direction Y is defined as H1 to H5, and the heating amount distribution ratio is obtained by the following formula (2).

[0101] Heating distribution ratio (%) = Total heating at each location / Sum of total heating at all locations × 100…(2)

[0102] The results are shown in Figure 5 It should be noted that, in Figure 5 In the diagram, the positions of the five ceramic molded bodies from left to right along the Y-axis are represented as 1 to 5 on the X-axis.

[0103] like Figure 5 As shown, in Example 1, dielectric drying was performed with an electric field adjustment component positioned below the drying support platform unsupported by a conveyor belt, compared to Comparative Example 1, dielectric drying was performed without an electric field adjustment component positioned below the drying support platform unsupported by a conveyor belt. The deviation in the drying state of the ceramic molded bodies in the Y-direction was smaller. Specifically, in Comparative Example 1, the difference in the heating amount distribution ratio between the central ceramic molded body and the ceramic molded bodies at both ends was approximately 5%, while in Example 1, this difference in heating amount distribution ratio was suppressed to less than 1%.

[0104] Based on the above results, it is evident that, according to the present invention, a dielectric drying method and apparatus for ceramic molded bodies capable of suppressing deviations in the drying state of multiple ceramic molded bodies placed on a drying support table in the arrangement direction Y perpendicular to the conveying direction X can be provided. Furthermore, according to the present invention, a method for manufacturing ceramic structures capable of achieving uniform shape can be provided.

[0105] Symbol Explanation

[0106] 10, 10a, 10b: Ceramic molded bodies,

[0107] 11a: Top surface,

[0108] 11b: Lower end face,

[0109] 20: Drying support platform

[0110] 100: Dielectric drying device,

[0111] 110: Dielectric drying oven,

[0112] 120: Conveyor

[0113] 121: Conveyor belt,

[0114] 130: Upper electrode,

[0115] 140: Lower electrode,

[0116] 150: Electric field adjustment component.

Claims

1. A method for dielectric drying of ceramic molded bodies, comprising conveying multiple ceramic molded bodies arranged side-by-side along an arrangement direction Y perpendicular to the conveying direction X to the space between upper and lower electrodes on the upper surface of a drying support stage, and drying them by applying a high frequency between the electrodes, wherein... The drying support platform is conveyed via a conveyor with one or more conveyor belts, which support a portion of the drying support platform in the Y-direction of the arrangement. One or more electric field adjustment components are disposed in the region between the drying support platform (which is not supported by the conveyor belt) and the lower electrode, and in the region corresponding to the position of the ceramic molded body above in the vertical Z direction. The electric field adjustment component is composed of one or more materials selected from conductors and insulators with a relative permittivity of 1.0 or higher.

2. The dielectric drying method for ceramic molded bodies according to claim 1, wherein, The electric field adjustment component is a sheet material with a thickness of more than 20% and less than 100% of the thickness of the conveyor belt.

3. The dielectric drying method for ceramic molded bodies according to claim 1 or 2, wherein, The electric field adjustment component is made of one or more materials selected from metal, ceramic and resin.

4. The dielectric drying method for ceramic molded bodies according to claim 1 or 2, wherein, The position of the electric field adjustment component is moved according to the drying state of the ceramic molded body.

5. The dielectric drying method for ceramic molded bodies according to claim 1 or 2, wherein, The moisture content of the ceramic molded body is 1~60%.

6. The dielectric drying method for ceramic molded bodies according to claim 1 or 2, wherein, The ceramic molded body is a honeycomb molded body having partitions that divide and form multiple pores extending from a first end face to a second end face.

7. The dielectric drying method for ceramic molded bodies according to claim 1 or 2, wherein, An auxiliary electrode, which is a porous plate, is placed on the upper end face of the ceramic molded body in the vertical direction Z.

8. The dielectric drying method for ceramic molded bodies according to claim 1 or 2, wherein, The drying support platform has a perforated plate in the portion that contacts the lower end face of the plurality of ceramic molded bodies in the vertical direction Z.

9. The dielectric drying method for ceramic molded bodies according to claim 7, wherein, The perforated plate is an aluminum perforated plate.

10. The dielectric drying method for ceramic molded bodies according to claim 8, wherein, The perforated plate is an aluminum perforated plate.

11. A method for manufacturing a ceramic structure, comprising the dielectric drying method of the ceramic molded body according to any one of claims 1 to 10.

12. A dielectric drying apparatus for ceramic molded bodies, comprising an upper electrode, a lower electrode, a conveyor, and one or more electric field adjustment components; The conveyor has one or more conveyor belts that support a portion of the drying support platform in the arrangement direction Y, and can convey multiple ceramic molded bodies to the electrode space between the upper electrode and the lower electrode via the conveyor belts. The drying support platform is used to place the multiple ceramic molded bodies side by side in the arrangement direction Y, which is perpendicular to the conveying direction X. The one or more electric field adjustment components are disposed between the drying support platform (which is not supported by the conveyor belt) and the lower electrode, and in the region corresponding to the position of the upper ceramic molded body in the vertical direction Z. The electric field adjustment component is composed of one or more materials selected from conductors and insulators with a relative permittivity of 1.0 or higher.

13. The dielectric drying apparatus for ceramic molded bodies according to claim 12, wherein, The electric field adjustment component is a sheet material with a thickness of more than 20% and less than 100% of the thickness of the conveyor belt.

14. The dielectric drying apparatus for ceramic molded bodies according to claim 12 or 13, wherein, The electric field adjustment component is made of one or more materials selected from metal, ceramic and resin.

15. The dielectric drying apparatus for ceramic molded bodies according to claim 12 or 13, further comprising a drive mechanism capable of moving the position of the electric field adjustment component.

16. The dielectric drying apparatus for ceramic molded bodies according to claim 12 or 13, wherein, An auxiliary electrode, which is a porous plate, is placed on the upper end face of the ceramic molded body in the vertical direction Z.

17. The dielectric drying apparatus for ceramic molded bodies according to claim 12 or 13, wherein, The drying support platform has a perforated plate in the portion that contacts the lower end face of the plurality of ceramic molded bodies in the vertical direction Z.

18. The dielectric drying apparatus for ceramic molded bodies according to claim 16, wherein, The perforated plate is an aluminum perforated plate.

19. The dielectric drying apparatus for ceramic molded bodies according to claim 17, wherein, The perforated plate is an aluminum perforated plate.

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