JP2004352574A - Continuous baking method for baked body using electromagnetic wave, and tunnel type continuous baking furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a continuous baking method for baked bodies suitable for production of various forms in a small quantity where, to various kinds of bodies to be baked having individually different autoexothermic properties by microwaves, baking in accordance with the exothermic properties can simultaneously be performed in one microwave continuous baking furnace, and baked bodies of excellent quality can be obtained by satisfactory microwave heating. <P>SOLUTION: In the continuous baking method for baked bodies by which many kinds of baked bodies having different baking temperatures are continuously obtained by using the tunnel type continuous baking furnace at least provided with a heating/sintering region for performing microwave irradiation baking, the bodies to be baked having different baking temperatures are inserted into the heating/sintering region set to the baking temperature to the prescribed body to be baked in a state where the circumference of each body to be baked is surrounded by a susceptor formed with a material having the microwave exothermic properties in accordance with those of the body to be baked. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a continuous firing method for a fired body, and more particularly, to a continuous fired body capable of continuously obtaining various kinds of fired bodies having different firing temperatures by irradiation heat of electromagnetic waves (hereinafter referred to as microwaves). The present invention relates to a firing method and a continuous firing furnace.
[0002]
[Prior art]
In recent years, the use of microwave heating methods for firing objects to be fired, such as ceramic materials and fine ceramic materials, has made it possible to reduce firing time and achieve uniform firing compared to conventional methods. For practical use, various means have been developed to improve the quality of products and further rationalize production. On the other hand, there has been proposed a microwave continuous firing furnace that continuously obtains a fired body and enables mass production of the fired body (for example, see Patent Document 1). In such a sintering furnace, the sintering temperature of a sintering chamber divided by a heat insulating wall that transmits microwaves is changed so as to correspond to the sintering process of the sintering object in the conveying direction of the sintering object. Then, it is proposed to use a material having heat insulating properties and permitting microwave transmission for the heat insulating wall, gradually increase the thickness thereof, and further provide an inner shell which generates heat by microwaves inside the heat insulating wall. Have been.
[0003]
The microwave continuous firing furnace having the above-described configuration has a feature that, in particular, a material to be fired having a self-heating characteristic by microwave similar to the material for forming the inner shell can be fired in a large amount. For this reason, when many types of objects to be fired having different heat generation characteristics are fired in large quantities, it is necessary to change the material of the inner shell that generates heat by microwaves according to the object to be fired. However, changing the material of the inner shell according to the object to be fired from the structure of the integrated continuous firing furnace requires a considerable amount of time and labor, and a large number of objects to be fired having different heat generation characteristics are required. In order to perform firing, a plurality of continuous firing furnaces having an inner shell made of the same material as the heat generating characteristics corresponding to each of the fired bodies are prepared, and designed in accordance with the self-heating characteristics of each fired body. It is necessary to perform firing by selecting a furnace that is used. Therefore, the above-mentioned conventional method is not suitable for small-quantity multi-product production. As described above, the prior art leaves a problem to be solved from the viewpoint of coping with small-quantity multi-product production and economic efficiency.
[0004]
[Patent Document 1]
JP-A-2002-130955
[Problems to be solved by the invention]
Accordingly, it is an object of the present invention to simultaneously perform firing in accordance with the heat generation characteristics on multiple types of objects to be fired having self-heating characteristics by individually different microwaves in one microwave continuous firing furnace. An object of the present invention is to provide a continuous firing method of a fired body which is excellent in economical efficiency, is suitable for small-quantity multi-product production, and can provide a fired body excellent in quality by good microwave heating.
[0006]
[Means for Solving the Problems]
The above object is achieved by the present invention described below. That is, the present invention provides [1] continuously obtaining various types of fired bodies having different firing temperatures by using a tunnel-type continuous firing furnace provided with at least a heating / sintering region for firing by microwave irradiation. In the method of firing a fired body, a fired body having a firing temperature different from the above is placed in the heating / sintering region set at a firing temperature condition for a predetermined fired body. This is a method for continuously firing a fired body using electromagnetic waves, characterized by being inserted in a state surrounded by a susceptor formed of a material having a microwave heat generation characteristic corresponding to the microwave heat generation characteristic of the fired body.
[0007]
Preferred modes of the continuous firing method of the fired body according to the present invention include the following [2] to [4]. [2] The method of [1], wherein the susceptor is further surrounded by a refractory heat insulating material. [3] The method for continuously firing a fired body according to any one of the above [1] and [2], wherein the heat-resistant temperature of the furnace material constituting the continuous firing furnace is lower than the heat-resistant temperature of the susceptor. [4] The method of [2] above, wherein the furnace material constituting the continuous firing furnace has a heat-resistant temperature lower than the heat-resistant temperature of the heat insulating material.
[0008]
Another embodiment of the present invention is a continuous firing furnace using a microwave for performing a continuous firing method of a fired body having any of the above-described [1] to [4]. It is a tunnel type continuous firing furnace.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in more detail with reference to preferred embodiments. The present inventors have conducted intensive studies in order to solve the above-described problems of the prior art, and as a result, in the heating and sintering region of the continuous firing furnace, a region corresponding to the size of each object to be fired, and If the heating and sintering regions having the heat characteristics matching the microwave heat generation characteristics (hereinafter referred to as “self-heating characteristics”) of the individual objects to be fired can be appropriately formed, then various types of substrates having different self-heating characteristics can be obtained. It has been found that the fired body can be fired simultaneously in the same continuous firing furnace set at a predetermined temperature condition, which makes it possible to cope with small-quantity, high-mix production, and significantly improves the economic efficiency. Thus, the present invention has been achieved.
[0010]
In the method for continuously firing a fired body according to the present invention, a tunnel-type continuous firing furnace provided with at least a heating / sintering region for firing by microwave irradiation is used, and the temperature condition of the heating / sintering region is set to a predetermined value. Is set to the firing temperature at which the object to be fired is fired, and another type of object to be fired having a different firing temperature from the above is inserted into the region. Then, at the time of insertion, the periphery of the object to be fired is surrounded by a susceptor formed of a material having self-heating characteristics by microwaves according to the self-heating characteristic of the object to be fired. According to such a method, a plurality of types of sintering with different sintering temperatures can be performed in the same sintering furnace without changing the configuration of the furnace material and the like in the tunnel type continuous sintering furnace and the set temperature conditions during operation from a normal state. The body can be obtained continuously.
[0011]
As a method of surrounding the body to be fired with a susceptor, a method of surrounding the whole body to be fired using a susceptor having a shape as shown in FIG. 1A or a method of surrounding the body as shown in FIG. And a method in which a susceptor having a shape in which the front and rear in the traveling direction of the continuous furnace are opened is used, and the inside of the susceptor is pseudo-enclosed in a tunnel-type mode similar to the continuous furnace. The number of objects to be fired surrounded by these susceptors is preferably one, but in some cases a plurality of objects to be fired may be surrounded. In a more preferred embodiment of the present invention, the periphery of the susceptor is further surrounded by a fire-resistant heat insulating material.
[0012]
The susceptor used in the present invention is formed using a material made of a material having self-heating characteristics by microwaves according to the self-heating characteristics of the object to be fired. For example, when the object to be fired is made of alumina, an alumina susceptor is used. When the object to be fired is made of zircon, a zirconous susceptor is used, and the object to be fired is made of SK32 refractory brick. If so, use a cordierite susceptor or chamotte susceptor. And it is preferable to surround these susceptors with a heat insulating material. The material of the susceptor is preferably substantially the same as the component of the object to be fired, but similar components and other materials can be used as long as the temperature difference of the self-heating characteristic is within about 50 ° C.
[0013]
Further, as the refractory heat insulating material surrounding the periphery of these susceptors, it is preferable to use a material having a heat resistance temperature higher than the firing temperature by 50 ° C. or more. More preferably, a material having a heat resistance temperature higher than the firing temperature by 100 ° C. or more is preferably used. For example, it is preferable to use, for example, an alumina-based heat-insulating fiber board that can withstand 1,700 ° C. as the fire-resistant heat-insulating material used when firing an alumina-based material to be fired at 1,600 ° C.
[0014]
In the firing method of the fired body of the present invention having the above-described configuration, the susceptor and, if necessary, the heat insulating material disposed around the susceptor can withstand the firing temperature required for the firing processing of the fired body. It is sufficient to use a material having heat resistance. On the other hand, as a furnace material attached to the tunnel-type microwave continuous firing furnace, a furnace material having a lower heat-resistant temperature than the above-mentioned susceptor or heat-insulating material and having inferior heat-resistant characteristics can be used. Therefore, according to the method of the present invention, there is also an advantage that the furnace material attached to the firing furnace can be used without being worn.
[0015]
According to the firing method of the fired body according to the present invention having the above-described configuration, in order to continuously and continuously fire a specific body to be fired, the basic design of a tunnel-type microwave continuous firing furnace and operating conditions are reduced. The temperature of the furnace in a continuous furnace in which the heating and sintering area is maintained at a predetermined temperature gradient with a predetermined microwave output only by a simple means of disposing an appropriate susceptor in the furnace without change. Can be obtained without any significant change in the continuous firing without any problem, and at the same time, different types of fired bodies fired at a temperature higher than the set temperature of the continuous firing furnace. In the above, a different type of fired body having a higher firing temperature than the steady fired body is surrounded by a susceptor having a self-heating characteristic by microwaves equal to or preferably equal to or higher than the fired body, and a tunnel type. To the heating and sintering area of the continuous microwave oven.
[0016]
Furthermore, if the material of the susceptor is appropriately selected, it is possible to obtain different types of fired bodies fired at a temperature lower than the set temperature of the continuous firing furnace only by a simple means of surrounding the susceptor. However, according to the study of the present inventors, when obtaining a fired body that is fired at a temperature lower than the set temperature of the continuous firing furnace, the temperature of the susceptor increases due to the temperature inside the continuous firing furnace. Therefore, it is desirable to surround the susceptor with a heat insulating material made of the above-mentioned materials.
[0017]
Further, according to the firing method of the fired body according to the present invention in which the susceptor is surrounded by a heat insulating material and a heat insulating layer is provided, the influence on the temperature in the furnace maintained at a predetermined temperature gradient is more advanced. Is suppressed, and since the influence from the furnace temperature on the region surrounded by the susceptor can be more highly suppressed, the inside of the region surrounded by the susceptor is in a state where the desired temperature condition is stably maintained. It becomes a heating and sintering area. Further, by surrounding the susceptor with a heat insulating material, it is possible to obtain a fired body fired at a firing temperature different from the furnace temperature, compared to a case where the fired body is simply surrounded by the susceptor. Become. As a result, by steady operation in the tunnel type microwave continuous firing furnace, it is possible to obtain a steady fired body and, at the same time, appropriately obtain various kinds of fired bodies having individually different firing temperatures as needed. .
[0018]
Whether to surround the susceptor with a heat insulating material may be appropriately determined. For example, when firing an object to be fired whose firing temperature is higher than the temperature of the continuous furnace maintained at a predetermined temperature gradient, it is desirable to further surround the susceptor with a heat insulating material in order to prevent heat radiation from the susceptor. On the other hand, when firing an object to be fired whose firing temperature is lower than the temperature of the continuous furnace maintained at a predetermined temperature gradient, the temperature of the susceptor and the temperature of the object to be fired increase due to heat radiation from the furnace. In this case as well, it is preferable to surround it with a heat insulating material in order to prevent this.
[0019]
As described above, according to the firing method of the fired body according to the present invention, the firing temperature is controlled using a tunnel type microwave continuous firing furnace in which the furnace temperature is maintained at a predetermined temperature gradient by a predetermined microwave output. Can simultaneously produce various desired fired bodies, so that it is economical to produce many kinds and small quantities. Further, according to the firing method of the fired body according to the present invention, the heat resistance of the furnace material constituting the microwave continuous firing furnace to be used can be configured to be lower than the conventional one, Excellent economy.
[0020]
【Example】
Next, the present invention will be described in more detail with reference to Examples and Comparative Examples.
(Example 1)
In this example, a tunnel-type microwave continuous firing furnace in which the heating and sintering region was maintained at 1,350 ° C. was used. Then, an alumina body to be fired having a size of 150 × 150 × 30 mm made of alumina powder having a purity of 99.6% as a main raw material, and the whole body to be fired was formed into a shape as shown in FIG. In the state surrounded by the susceptor, it was transported to the heating / sintering area. At this time, an alumina susceptor made of the same material as the above-mentioned object to be fired and having a purity of about 99% as a main raw material was used. As the susceptor, a susceptor that surrounds the entirety of the object to be fired and has a shape in which the distance between the object to be fired and the susceptor is about 30 to 60 mm when the object to be fired is arranged. In this embodiment, the periphery of the susceptor was further covered with a 50-mm-thick alumina heat insulating material. As a result, a fired body having substantially the same density as the fired body fired at 1,500 ° C., which is the firing temperature of the alumina fired body, was obtained.
[0021]
Further, the above-mentioned susceptor was used except that the inside of the susceptor had a shape of a continuous furnace as shown in FIG. In the same manner as in, the object to be fired was transported to the heating / sintering area. That is, the interval between the object to be fired and the susceptor was about 30 to 60 mm, and a 50-mm-thick alumina heat insulating material was used. As a result, similarly to the above, in a tunnel type microwave continuous firing furnace in which the heating and sintering region was maintained at 1,350 ° C., a fired body having a density substantially equal to that of a fired body fired at 1,500 ° C. Could be obtained.
[0022]
Further, the same alumina powder molded body having a purity of 99.6% as used above was used as the object to be fired, and only the alumina-based susceptor having the shape shown in FIG. And transported to a continuous furnace. As a result, a fired body having almost the same quality as a fired body sintered at 1,400 ° C., which is an appropriate firing temperature of the fired body, was obtained.
[0023]
(Example 2)
The alumina fired body used in Example 1 was a zircon fired body mainly composed of zircon sand and zircon flour containing about 98% zircon, and a zircon susceptor mainly composed of zircon and mullite. The fired zircon body was transported to the heating and sintering region in a state surrounded by a susceptor having the shape shown in FIG. 1A, in the same manner as in Example 1 except that the heat insulating material was not used. As a result, a fired body having a density substantially equal to that of the fired body fired at 1,460 ° C., which is the firing temperature of the zircon fired body, was obtained.
[0024]
Further, the susceptor is the same as above except that the inside of the susceptor has a shape similar to that of a continuous furnace as shown in FIG. The object to be fired was transported to the heating / sintering area. As a result, in the same manner as described above, in a tunnel type microwave continuous furnace in which the heating and sintering region was maintained at 1,350 ° C., a fired body having a density substantially equal to that of the fired body fired at 1,460 ° C. I got it.
[0025]
(Example 3)
The alumina fired body used in Example 1 was used as a fired body of SK32 refractory brick mainly made of chamotte and refractory clay, and a cordierite susceptor was used. It was transported to the heating and sintering area in the same manner as in Example 1 except that a heat insulating layer made of an alumina / silica heat insulating board was provided. As a result, a fired body having almost the same density as the fired body fired at 1,270 ° C., which is the firing temperature of the fired SK32 refractory brick, was obtained.
[0026]
Further, the susceptor is the same as above except that the inside of the susceptor has a shape similar to that of a continuous furnace as shown in FIG. The object to be fired was transported to the heating / sintering area. As a result, in the same manner as described above, in a tunnel type microwave continuous furnace in which the heating and sintering region was maintained at 1,350 ° C., a fired body having a density substantially equal to that of the fired body fired at 1,270 ° C. I got it.
[0027]
【The invention's effect】
As described above, according to the present invention, although the temperature condition of the heating and sintering region is set to a value corresponding to the firing temperature of the predetermined object to be fired, the microwave continuous firing furnace is used. For various types of objects to be fired having different firing temperatures, optimal firing can be performed simultaneously according to the individual firing temperature, and various types of fired materials with excellent quality can be obtained by microwave heating. A continuous firing method for a fired body suitable for multi-kind production and excellent in economic efficiency, and a tunnel-type continuous firing furnace are provided.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an example of the shape of a susceptor and a heat insulating layer used in the present invention.

Claims (5)

In a firing method of a fired body for continuously obtaining various types of fired bodies having different firing temperatures using a tunnel-type continuous firing furnace provided with at least a heating / sintering region for firing by electromagnetic wave irradiation, In the heating and sintering region set to the firing temperature condition for the fired body, a fired body having a firing temperature different from the above is set according to the electromagnetic wave heating characteristic of the fired body around the fired body. A method of continuously firing a fired body using electromagnetic waves, wherein the method is inserted while being surrounded by a susceptor formed of a material having electromagnetic wave heating characteristics. The method for continuously firing a fired body according to claim 1, further comprising surrounding the susceptor with a refractory heat insulating material. The method for continuously firing a fired body according to claim 1, wherein a heat-resistant temperature of a furnace material constituting the continuous firing furnace is lower than a heat-resistant temperature of the susceptor. The method for continuously firing a fired body according to claim 2, wherein the heat-resistant temperature of the furnace material constituting the continuous firing furnace is lower than the heat-resistant temperature of the heat insulating material. A continuous firing furnace using an electromagnetic wave for performing the continuous firing method for a fired body according to any one of claims 1 to 4.

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