JP2008174428A - Electromagnetic induction heating cooker and method of manufacturing electromagnetic induction heating cooker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electromagnetic induction heating cooker manufactured by a simple production process and securing firm lamination and boiling prompting effect in water boiling conditions and a method of manufacturing the electromagnetic induction heating cooker. <P>SOLUTION: The method of manufacturing the electromagnetic induction heating cooker comprises a step of forming a molding by injecting a mixture of carbon granular powder with a binder into a molding mold, compacting and curing to mold a molding precursor and placing the molding precursor in an oven under an oxygen-free state replaced by nitrogen and firing, and a step of applying a slurry liquid prepared by dispersing ceramic powder and additives in a solvent on the molding and after drying, carrying out a firing treatment. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to, for example, a pot or a pot-shaped cooker used for dielectric heating, and more particularly, to an induction heating cooker having a structure in which ceramics are laminated on a carbon-based surface and a method for manufacturing the same. .

  A dielectric heating cooker is configured such that an eddy current generated by an induction heating coil generates heat in a magnetic metal, and is used in a stove or rice cooker. However, magnetic metals such as iron and stainless steel have poor thermal conductivity. Therefore, in order to quickly and uniformly heat the food, a rolled clad material made of a metal having excellent heat conductivity such as aluminum or copper was used. However, it has been difficult to obtain a molded product having an arbitrary shape, particularly a thick wall.

  For this reason, a pan placed on the cooker body, an induction heating coil that is provided so as to face the outer bottom surface portion or the outer peripheral surface portion of the pan, and a control means that controls energization of the induction heating coil An induction heating cooker is proposed in which the pan is made of graphite and the surface of the pan is coated with a fluororesin (see, for example, Patent Document 1).

  Further, an electromagnetic heating cooker has been proposed in which a fluorine-based synthetic resin film is deposited on the surface of a carbon compression molding material made of natural carbon or artificial carbon, and generates heat by a high-frequency magnetic field (for example, Patent Documents). 2).

  However, the aggregates of carbon particles have the problem of being brittle and easy to break due to the mode accompanying the condensation of particles, and give sufficient resistance against damage due to application of large stress such as dropping or collision There was a need to do.

  According to Patent Document 1, a sintered body obtained by agglomerating high carbon-containing powder particles such as coke at a high temperature of 1000 to 3000 ° C. has appropriate conductivity and dielectric properties, such as conventional iron Instead of this, it can be used in a cooking device of dielectric heating, for example, a rice cooker. Among these, the cooker easily cuts the cooked product by cutting the carbon sintered body into a pan shape and then applying fluorocarbon resin to the pan surface or glassy carbon on the pan surface. Thus, a function for facilitating cleaning and a function for improving wear resistance are provided.

  In addition, a crucible containing Si is placed on the upper part of the fired body containing SiC as a main component, the crucible is heated to bring Si into a molten state, and a melt of Si is supplied to the surface of the fired body through the holes of the crucible. A method for producing a Si—SiC composite material impregnated with Si has been proposed (see, for example, Patent Document 3).

  In addition, a sintered body manufactured in advance is placed in a mold, a raw material powder that becomes a porous ceramic body is filled in the mold, and is molded by pressure forming and then fired, and then a ceramic joined body is manufactured. A method has been proposed (see, for example, Patent Document 4).

Furthermore, the main object is to produce a high-strength laminated ceramic thin plate without warping, and the molded body is laminated so that the surfaces with a low powder filling rate in the thickness direction of the sheet-like ceramic production form are in contact with each other, A method for manufacturing a laminated ceramic thin plate to be fired has been proposed (see, for example, Patent Document 5).
Japanese Patent Application Laid-Open No. 09-075211 Japanese Patent Laid-Open No. 09-070352 JP 2003-071555 A Japanese Patent Laid-Open No. 06-144941 Japanese Patent Laid-Open No. 07-291738

  However, in the said patent document 1, since the fluororesin etc. were apply | coated to the surface of the molded product which cut the block, there existed a subject that the effect which accelerates | stimulates the bubble generation at the time of boiling was impaired. For this reason, it is preferable to use a material configuration in which the surface is protected with porous ceramics.

  However, according to the conventional method for manufacturing a ceramic laminate, in the case of Patent Document 4 in which ceramic raw material powder is placed on a sintered body, pressed, solidified, and sintered, as an example, a molded product that has already been fired. This is achieved by stacking dissimilar materials using However, since the cooker container is a molded product with a pan-shaped curved surface, the molded carbon material, which is a molded substrate, holds the container-shaped molded product with extremely high shape accuracy in a pressurizing device having pores. It is very difficult to provide a surface, and it is impractical to withstand the pressing force required to firmly bond both materials during molding.

  On the other hand, after the slurry-like ceramic is dried, the container-like molded product is used by using the “method for producing a laminated ceramic thin plate” of Patent Document 5 in which the upper surfaces having a low powder filling rate are stacked and pressure bonded together. If it is going to be laminated on the surface, there is a problem that the dried ceramic precursor is brittle and it is difficult to form a smooth surface by cracking when forming a curved surface.

  In addition, the adhesiveness between ceramics and carbon aggregates, particularly graphite, is essentially inferior, and it is difficult to achieve an embodiment that can withstand practical use as a cooking device.

  The present invention has been made to solve the above-described problems, and can simplify the manufacturing process and secure a strong lamination state, and can ensure an excellent boiling promotion effect in a boiling state of water. An object of the present invention is to provide a method for manufacturing a cooking device and an induction heating cooking device.

In the method of manufacturing an induction heating cooker according to the present invention, a precursor molded product is formed by putting a mixture of carbon particles and a binder into a mold, and compressing and curing the mixture. Place in a substituted oxygen-free furnace and perform a firing process to produce a molded product, and apply a slurry liquid in which ceramic powder and additives are dispersed in a solvent to the molded product, dry it, and fire And a process for performing processing.
In addition, the ceramic powder coated on the molded product is formed by being bonded without filling the voids provided between the particles.

  The method for manufacturing an induction heating cooker according to the present invention can simplify the manufacturing process because both the carbon aggregate and the ceramic can ensure the lamination state in the precursor state and simultaneously perform the firing process. Since the ceramic can enter the pores of the carbon aggregate formed during firing, it has an effect of ensuring a strong laminated state. Moreover, since the ceramic coating film which comprises the inner surface of a cooking vessel container is equipped with the pore opened on the surface, the boiling promotion effect excellent in the boiling state of water is securable.

Embodiment 1 FIG.
1 and 2 are diagrams showing Embodiment 1, FIG. 1 is a sectional view of an inner pot 10 of a jar rice cooker, and FIG. 2 is a manufacturing process diagram of the inner pot 10 of a jar rice cooker.

  An inner pot 10 of a jar rice cooker that is a dielectric heating cooker in the present embodiment has a cross-sectional structure shown in FIG. That is, by covering the inner surface portion of the carbon aggregate 1 which is a base material with the ceramic layer 2, the carbon aggregate 1 is protected from scratches and damages due to the weak points of the carbon aggregate 1. In addition, it has the effect of promoting the generation of bubbles at the time of boiling, thereby providing an effect of promoting stirring during cooking.

  Below, the manufacturing method of the inner pot 10 of the jar rice cooker in Embodiment 1 is explained in full detail, referring FIG.

  Carbon particles having a particle size distribution of 10 to 300 μm obtained by firing natural wood, seed shell carbide, petroleum coke or coal coke at 2600 ° C. to 3000 ° C. in which carbon becomes graphite crystals in an oxygen-free state. A precursor molded product was obtained by mixing (kneading) a phenolic resin with a binder as a binder into a pan-like compression molding mold and compressing and curing.

  If the carbon particles do not have graphite crystals, the electrical conductivity is inferior and dielectric heating cannot be performed sufficiently. In addition, when a mixture of carbon particles and phenol resin is molded without imparting compressive force in the mold, voids remain between the particles and sufficient bonding strength cannot be secured, and cracks may occur during firing Therefore, it is not preferable.

  The precursor molded product, which is the compression molded product described above, is placed in an oxygen-free furnace substituted with nitrogen, and is fired in an oxygen-free state at 700 ° C. or higher, preferably 1300 ° C. or higher (first baking treatment). To obtain a pot-shaped molded article having excellent electrical conductivity. At this time, the phenol resin which is a binder of the carbon aggregate 1 is mainly decomposed at 400 to 450 ° C. and diffuses and contracts while forming fine pores in the carbon aggregate 1. Therefore, in the firing treatment in which the temperature is slowly raised and cooled at 1 to 10 ° C./hr, the firing is performed at a temperature raising rate of 1 to 3 ° C./hr only when the temperature is raised to 350 to 550 ° C.

  In addition, when the content of the phenolic resin as a binder is high, or in the case of a molded product formed by injection molding instead of the compression molding of the present embodiment, binding occurs as the mixture flows during molding. Many materials are retained on the surface, and as a result, the pores formed tend to be extremely fine, so that the impregnation of the applied glassy ceramic, which is a subsequent step, becomes insufficient, and the mechanical accompanying the penetration into the pores In some cases, it is difficult to fix the coating film on the surface. When such extremely fine pores are retained on the surface and impregnation with glassy ceramics is difficult, a thin layer formed by retaining a large amount of binder formed on the surface is subjected to a firing treatment ( It is preferable to delete by blasting or sandpaper before the first baking treatment (deleting the surface layer). As a result, the glass ceramics can be sufficiently impregnated in the subsequent process.

  Next, the pot-shaped molded product that has been baked has the purpose of preventing breakage such as wear damage due to friction, etc. due to friction accompanying prevention of food adhering to cooking and removal of adhering food as a cooking utensil, and further providing a boiling promotion effect After applying ceramics as the surface treatment, the ceramic is fired at 1000 ° C. or higher, preferably 1300 ° C. or higher.

  The molded product has many pores generated when various materials generated mainly by decomposition of residual organic substances are scattered when the binder is carbonized. Moreover, when the mode of the coating film adhering to the surface layer is obtained only by adhesion, the bonding strength between the carbon particles constituting the carbon aggregate 1 is not sufficient, and the apparent strength including the desorption of the carbon particles at the time of peeling. It is hard to get. Furthermore, since graphitized carbon is inherently inferior in adhesion to ceramics, it is important to have a structure in which part of the coating penetrates into the pores in the surface layer and creates mechanical bonding force. is there.

  Therefore, by mixing glassy ceramics with the high melting point ceramics that make up the coating film, the size of each particle is adjusted so that ceramics with a high melting point and excellent mechanical strength such as wear remain on the surface layer. did. A mixture of high melting point ceramics and glassy ceramics is called ceramic powder. Further, the vitreous ceramic is referred to as a first ceramic, and the high melting point ceramic is referred to as a second ceramic. That is, the ceramic powder according to the present embodiment has a heat resistance equal to or higher than the use temperature as a cooking device, and easily impregnates the pores by entering into the pores and exhibiting fluidity when heated and melted. It is important to provide a mode for fixing the material. Specifically, the vitreous ceramic (glassy substance) includes a material smaller than the pore diameter of the molded product including the carbon powder particles obtained by the first baking treatment.

  Accordingly, high-melting-point ceramics having a high melting point such as boron nitride and silicon nitride as well as oxides such as zirconia and alumina are used as the ceramic powder. Further, it is preferable that the glassy particles contain silicon oxide or boron oxide and exhibit the behavior of being melted and exhibiting a low viscosity and filling the pores in the firing process in the next step. In addition to water, an organic solvent such as ethanol is used as the solvent in which the ceramic powder is dispersed, and a binder is added for the purpose of maintaining each particle during drying after application and maintaining the application state. As the additive, polyvinyl alcohol and its derivatives in which excessive ash content does not remain at the time of firing are suitable, and it is also effective to add surfactants and fats and oils that improve plasticity and dispersibility.

  Here, the mixing ratio of the high melting point ceramic powder and the vitreous particles was 2.5 to 5.0, preferably 10: 3.0 to 3.5, with respect to the former 10. The high melting point ceramic powder is not impregnated from the surface of the carbon aggregate 1 because it is larger than the pore diameter of the molded product including the carbon particles obtained by the first firing treatment. On the other hand, the vitreous ceramic is impregnated from the surface of the carbon aggregate in the application stage of the slurry liquid in which the above-described ceramic powder is dispersed and in the molten state at a high temperature. That is, the glassy ceramic (glassy substance) includes a material smaller than the pore diameter of the molded product including the carbon powder particles obtained by the first baking treatment. In the latter case, the vitreous ceramic is not bonded to the carbon aggregate, but covers the surface portion. The function to do is the main. Accordingly, the fired ceramic coating film is formed so as to have a fine void on the surface.

  In addition, the initial coating for forming the lower layer can be achieved by sufficiently impregnating the carbon aggregate 1, since the carbon aggregate 1 is impregnated and the surface is dried and then the next coating is performed. It is effective in producing peeling resistance.

  The slurry liquid in which the ceramic powder or the like is dispersed is applied several times until the inner surface of the pot-shaped molded product to be fired is uniformly wetted to a thickness of about 50 to 200 μm, and then left to stand. Allow to air dry. After the applied slurry is dried, it is held on the surface of the carbon aggregate 1 by baking (second baking) in a furnace maintained at 1000 ° C. or higher, preferably 1300 ° C. or higher. Furthermore, after the completion of firing, slow cooling of 1 to 10 ° C./hr is performed so that distortion based on the difference in stress generated at the time of cooling does not remain in parts having different curvatures and thicknesses of the molded product. This is effective in preventing defects such as cracks and deformation.

  The obtained ceramic coating film is formed by forming a rough surface with excellent wear resistance that is held in a state where many particles such as alumina having high hardness protrude on the surface. It was confirmed that it had sufficient resistance to deformation caused by falling and sufficiently fulfilled its function as a cooker.

  In addition, the provision of the ceramic coating provided the advantage of convenient cooking, such as promoting boiling in rice cooking and soup cooking, and promoting stirring of cooked rice and ingredients. Also confirmed.

Embodiment 2. FIG.
Regarding the inner pot 10 of the jar rice cooker, which is a molded product obtained by using a mixture containing a relatively small amount of the binder among the dielectric heating cookers having the same shape as the first embodiment, the manufacturing method will be described in detail below. Describe.

  In the present embodiment, the amount of the binder in the raw material is reduced, and the pores are increased and increased. Thereby, since the impregnation of the vitreous ceramic can be sufficiently performed, it is not necessary to delete the surface layer, and the process can be simplified. In addition, during the firing treatment of the molded product, firing and solidification of the ceramic is simultaneously achieved, thereby achieving efficient formation of the ceramic layer.

  FIG. 3 is a diagram showing the second embodiment, and is a manufacturing process diagram of the inner pot 10 of the jar rice cooker.

  A mixture of graphite particles of 300 μm or less of graphite crystals obtained by firing carbon at 2600 ° C. to 3000 ° C. with carbonized or coke of natural wood in an oxygen-free state, and a powdery phenol resin that is a binder for the particles. It was put into a pan-shaped compression molding mold and compressed and cured to obtain a precursor molded product. At this time, the mold has a temperature suitable for curing the phenolic resin, for example, 120 to 210 ° C., and preferably has a sufficient wettability to the carbon particles as a high temperature state that gels in 30 to 90 seconds. It is important. The binder is a thermosetting resin that decomposes and scatters at a temperature equal to or lower than a temperature used for a firing treatment (described later).

  Next, the ceramic which comprises the surface layer provided with the function of preventing breakage such as wear damage due to friction accompanying the prevention of adhesion of cooked food and the removal of the adhering ingredients is applied. The slurry liquid in which the ceramic powder and the like used here is dispersed is applied to about 50 to 200 μm so as to uniformly wet the inner surface of the pan-shaped molded product, air-dried, and then kept in a furnace at 1000 ° C. or higher, preferably 1300 ° C. After securing the state firmly held on the surface of the carbon aggregate 1 by firing in, a slow speed of 1 to 10 ° C. to near room temperature so as not to leave distortion in the coating film and at the interface with the molded product The ceramic coating was formed by cooling with.

  The ceramics constituting the above-mentioned coating film are a mixture of glassy ceramics (glassy material) having a melting point of 1000 ° C. or less and high melting point ceramics having excellent mechanical strength such as wear without melting at a firing temperature or higher, It is preferable that the former is a content rate of 20-40 vol%. The particle size of the glassy ceramic is smaller than that of the high melting point ceramic. In addition to water, an organic solvent such as ethanol is used as a solvent to disperse the ceramic powder. It is a binder that keeps the surface of the pot-shaped molded product without peeling when dried after coating. Polyvinyl alcohol and its derivatives that are difficult to remain may be suitably used, and surfactants or fats and oils that improve plasticity and dispersibility may be added.

  In a pot-shaped molded product with ceramics applied to the inner surface, the binder is carbonized during the firing process, and various substances are scattered to generate many pores. The binder and slurry liquid additives decompose and scatter. At this time, in the initial firing step mainly in a temperature range of 350 to 600 ° C. where the organic material-derived decomposition product included in the binder is applied and dissipated from the pot-shaped molded product, the ceramic layer is suitable. It is necessary to provide an embodiment having the pores. Next, as the pot-shaped molded product proceeds and the pores are formed on the surface, the amount of scattered matter from the decomposed product decreases rapidly. It is an essential condition that the behavior of impregnating the pores of the molded product is not hindered.

  Therefore, at 350 to 600 ° C., preferably 300 to 750 ° C. at which pore generation develops in a pot-shaped molded product, the temperature rise and cooling in other temperature ranges are performed at 1 to 10 ° C./hr, whereas 1 to It is important to maintain a moderate temperature increase rate of 3 ° C./hr.

  Further, when the temperature rises and reaches around 1000 ° C., the glassy substance containing silicon oxide or boron oxide melts and exhibits fluidity, and is mechanically applied by impregnating the pores generated in the above-described firing step. Since the film is fixed, it is preferable that the glassy substance exhibits a low viscosity when melted. On the other hand, even oxides such as zirconia and alumina and non-oxides such as boron nitride and silicon nitride do not melt at the firing stage where the melting point is high and the temperature is raised to 1300 ° C. In ceramics, particles are fixed on the surface of the pot-shaped molded product using a glassy material as a binder, but only an amount of glassy material that does not lead to filling the voids between the particles is mixed. Stop to make.

  The ceramic coating film obtained by the above means is highly wear-resistant because particles such as alumina with high hardness are retained on the surface, and it is sufficiently resistant to deformation during cooking and dropping of articles. It was confirmed that it had sufficient resistance and sufficiently fulfilled the function as a cooker.

Embodiment 3 FIG.
About the inner pot 10 of the jar rice cooker which is a dielectric heating type cooking device of the same shape as Embodiment 2, a manufacturing method is explained in full detail below.

  Although the present embodiment is not as large as the first embodiment, even if the pore formation is relatively fine and impregnation with the vitreous ceramic is difficult, the vitreous does not contain ceramics such as non-molten alumina. In addition to being easily impregnated by placing a ceramic-only layer, pores are easily left without being excessively filled with vitreous ceramic in the voids where non-molten ceramic particles are in contact with each other. Therefore, as compared with the first and second embodiments, the molding method is easy to impregnate and the surface layer having a boiling effect is easily formed.

  FIG. 4 shows the third embodiment, and is a manufacturing process diagram of the inner pot 10 of the jar rice cooker.

  A precursor molded product obtained by compression molding and curing a mixture of graphite crystal grains obtained by firing carbon at 2600 ° C. to 3000 ° C. and a phenol resin as a binder into a pan-shaped compression molding die. The ceramic which forms the surface layer having the function of preventing damage such as abrasion damage due to friction accompanying the prevention of the adhesion of cooked food and the removal of the adhering material is applied.

  Here, first, after firing with a first slurry liquid, a glass ceramic having a melting point of 1000 ° C. or less and ethanol that is a solvent, and a binder that holds the surface of the pot-shaped molded product without peeling off at the time of drying after coating. The ash content of polyvinyl alcohol, a surfactant added to improve the plasticity and dispersibility, oils and fats, and the like were used, and this was applied and then air-dried.

  Next, a mixture of a glassy ceramic having a melting point of 1000 ° C. or less and a high-melting ceramic having excellent mechanical strength such as wear without melting at the firing temperature is mixed in a ratio of 1: 3 to 5 similarly. Add ethanol, polyvinyl alcohol, which is a binder that keeps the surface of the pan-shaped molded product without peeling when dried after coating, surfactants and oils that improve plasticity and dispersibility, etc. The second slurry was applied over the glassy ceramic and then air-dried.

  The first slurry liquid containing only glass ceramics as the base is to form a thin film of several μm to several tens μm with a uniform thickness so that the glassy ceramics can easily impregnate the pot-shaped molded product. The second slurry liquid mainly composed of high-melting-point ceramics that does not melt at the firing temperature located in the upper layer forms a slightly thick thin film of about 30 to 80 μm.

  Next, this is firmly held on the surface of the carbon aggregate 1 by a baking treatment (heat treatment) in a furnace kept at 1000 ° C. (first temperature) or more, preferably about 1300 ° C. (second temperature). After securing the state, a ceramic coating was formed by cooling at a slow rate of 1 to 10 ° C. to near room temperature so as not to leave distortion in the coating film and at the interface with the molded product. The heat treatment is performed in an inert gas atmosphere excluding oxygen.

  In a pot-shaped molded product with ceramics applied to the inner surface, the binder carbonizes with firing, and various substances are scattered to generate many pores. At this time, in the initial firing step mainly in a temperature range of 350 to 600 ° C. where the organic material-derived decomposition product included in the binder is applied and dissipated from the pot-shaped molded product, the ceramic layer is suitable. It is necessary to provide an embodiment having the pores. Next, in the stage where the decomposition of the decomposed product suddenly decreases as the pot-shaped molded product is baked and pores are formed on the surface, the glassy ceramic in the ceramic coating layer is melted to form a pot-shaped mold. It is an indispensable condition to complete the scattering of decomposition products so as not to hinder the behavior of impregnating the pores formed by the product. Therefore, at 350 to 600 ° C., preferably 300 to 750 ° C. at which pore generation develops, a moderate temperature increase rate of 1 to 3 ° C./hr is maintained, and temperature increase and cooling in other temperature ranges are 1 to 10 ° C./hr. It is important to do in

  Furthermore, when the temperature rises and reaches around 1000 ° C., the glassy substance melts and exhibits fluidity, and has an aspect in which the coating film is mechanically fixed by impregnating the pores generated in the above-described firing stage. At this time, it is preferable that the glassy substance exhibits a low viscosity when melted. On the other hand, oxides such as zirconia and alumina, and non-oxides such as boron nitride and silicon nitride, which have a high melting point and do not melt at the firing stage where the temperature is raised to 1300 ° C., bind glassy ceramics. Particles are fixed on the surface of the pan-shaped molded product as a material, but are mixed and adjusted to an amount that does not fill the voids between the particles. Stop on.

  The ceramic coating film obtained by the above means is highly wear-resistant because particles such as alumina with high hardness are retained on the surface, and it is sufficiently resistant to deformation during cooking and dropping of articles. In addition, the formation of a surface layer containing fine bubbles having a function of promoting the boiling state was confirmed from the fact that the generation of bubbles increased during boiling.

It is a figure which shows Embodiment 1, and is sectional drawing of the inner pot 10 of a jar rice cooker. It is a figure which shows Embodiment 1, and is a manufacturing process figure of the inner pot 10 of a jar rice cooker. It is a figure which shows Embodiment 2, and is a manufacturing process figure of the inner pot 10 of a jar rice cooker. It is a figure which shows Embodiment 3, and is a manufacturing process figure of the inner pot 10 of a jar rice cooker.

Explanation of symbols

  1 Carbon aggregate, 2 Ceramic layer, 10 Jar rice cooker inner pot.

Claims (17)

A precursor molded product is formed by putting a mixture of carbon particles and a binder into a mold and compressing and curing the mixture.
Removing the surface layer of the precursor molded product,
The precursor molded product from which the surface layer has been removed is placed in an oxygen-free furnace substituted with nitrogen, and a first firing treatment is performed to produce a molded product,
A slurry liquid in which ceramic powder and an additive are dispersed in a solvent is applied to the molded product,
A method for producing an induction heating type cooking device, wherein a second baking treatment is performed after the applied slurry is dried.   The method for manufacturing an induction heating cooker according to claim 1, wherein the ceramic powder includes a vitreous substance that exhibits a liquid state at a temperature equal to or higher than the temperature of the second baking treatment.   3. The induction heating cooker according to claim 2, wherein the vitreous substance includes a material having a diameter smaller than a pore diameter of the molded product including the carbon particles obtained by the first baking treatment. Production method.   The ceramic powder is larger than the pore diameter of the molded article including the carbon particles obtained by the first firing treatment, and contains unmelted particles at the temperature of the second firing treatment. The method for manufacturing an induction heating cooker according to any one of claims 1 to 3.   The amount of the vitreous substance mixed in the ceramic powder is set to an amount that does not fill a void formed by infusible powder particles at the temperature of the second baking treatment. The manufacturing method of the induction heating type cooking appliance as described in 2. A precursor molded product is formed by putting a mixture of carbon particles and a binder into a mold and compressing and curing the mixture.
A slurry liquid in which ceramic powder and an additive are dispersed in a solvent is applied to the precursor molded product,
A method for producing an induction heating cooker, wherein a baking treatment is performed after the applied slurry is dried.   The method for manufacturing an induction heating cooker according to claim 6, wherein the binder is a thermosetting resin that decomposes and scatters at a temperature equal to or lower than a temperature used for the baking treatment.   The ceramic powder is a vitreous substance having a melting point equal to or lower than the temperature of the firing treatment, and includes a material having a particle size smaller than that of the unmelted powder particles at the firing treatment temperature. 6. A method for producing an induction heating cooker according to 6.   The induction heating cooker according to claim 8, wherein the baking is performed at a temperature equal to or higher than a temperature at which the binder and the additive of the slurry liquid are decomposed and scattered and the vitreous substance is melted. Production method.   The induction heating according to claim 8 or 9, wherein an amount of the vitreous substance mixed in the ceramic powder is an amount that does not fill a void formed by infusible powder particles at the temperature of the baking treatment. A method of manufacturing a cooking device. A precursor molded product is formed by putting a mixture of carbon particles and a binder into a mold and compressing and curing the mixture.
Applying a first slurry liquid in which a vitreous substance that melts and penetrates into pores of the precursor molded article at a first temperature is dispersed in a solvent together with an additive,
Applying a second slurry liquid in which a mixture of the vitreous material and insoluble particles at a second temperature higher than the first temperature is dispersed;
The manufacturing method of the induction heating type cooking appliance characterized by performing heat processing in the arbitrary temperature of said 1st temperature or said 2nd temperature range.   The method for manufacturing an induction heating cooker according to claim 11, wherein the heat treatment is performed at a temperature equal to or higher than a melting point of the vitreous substance.   The method for manufacturing an induction heating cooker according to claim 11 or 12, wherein the heat treatment is performed in an inert gas atmosphere excluding oxygen.   The amount of the vitreous substance mixed in the ceramic powder is set to an amount that does not fill a void formed by unmelted powder particles at the temperature of the heat treatment. A method of manufacturing an induction heating cooker. A precursor molded product formed by compressing and curing a mixture of carbon particles and a binder;
A first ceramic that penetrates into the pores of the precursor molded product and covers the surface portion;
An induction heating cooker comprising: a second ceramic formed on an upper layer of the first ceramic.   16. The induction heating cooker according to claim 15, wherein the second ceramic includes a material that does not fill pores of the precursor molded product.   The second ceramic is formed by bonding particles between the first ceramics and leaving many pores without filling a space provided between the particles. The induction heating cooker according to claim 16.

Images