JPH11221159A - Heat retaining cooker and manufacture therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve heat-retaining performance, be light-weighted, and excellent in economic efficiency by taking a metal excellent in thermal conductivity as a matrix, joining a raw material which has lower specific gravity and lower thermal conductivity than the metal to the outer peripheral part, and making at least a part of a joined part of the metal and low thermal conductive raw material as a complex by combining the metal and the raw material. SOLUTION: A container main body 1 of a heat insulating cooker is provided with a heat transfer part 2 formed of a metal excellent in thermal conductivity, which is disposed in the inner part of the container. Further, the outside of the container is provided with a heat insulating part 3 formed of a raw material which has a lower specific gravity and lower thermal conductivity. Further, in a joining part between the heat transfer part 2 formed of the metal excellent in thermal conductivity and the heat insulating part 3 formed of the low thermal conductivity raw material, there is provided a portion where the metal excellent in thermal conductivity enters voids of the low thermal conductivity raw material, that is, a complex part 4. The complex part 4 may be formed partially or uniformly, and further preferably it may be formed with a gradient. The joint strength of the metal excellent in thermal conductivity and the low thermal conductive raw material is enlarged by such complex.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooking device using an electromagnetic heating method, a cooking device using an electric resistance heating method and a flame heating method, and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, in cooking rice or boiled food,
An electromagnetic heating method has attracted attention instead of a conventional heating method using a flame such as gas or electric resistance. This is because, since the heating power is strong, the heating time at a high temperature can be reduced in a short time, and cooking without losing the deliciousness of the ingredients can be performed. In an electromagnetic heating type cooker, a metal having good heat conductivity, such as copper or an aluminum alloy, is used for the container body in order to improve the heating efficiency of the container body during cooking.

[0003] On the other hand, it is desirable to keep the cooked product in the container body of the cooker cool after the cooking is completed.
When a metal having excellent heat conduction as described above is used for the container body of the cooker, the heat escapes and is easily cooled. Therefore, there is a problem that heating for heat retention is required, and a lot of energy is consumed. If this container body can be constituted by a container having low thermal conductivity such as an earthen pot, for example, the heat retention will be improved, and thus energy for heat retention can be saved.

[0004] As described above, in a cooking device, it is desired to provide a container body having a low heat conductivity and a good heat retention property while transferring heat well to a cooked product during cooking. It is to be noted that the heat conductivity and the heat retention of the container main body in the cooker are not limited to the electromagnetic heating system, but are the same in the container main body using the electric resistance heating system or the gas flame heating system.

FIG. 3 shows a concrete example of a container body in a conventional electromagnetic heating type cooking device. In FIG. 3, a clad plate 7 of aluminum and ferrite stainless steel is used for the container. That is, ferrite-based stainless steel is used for the outer layer 9 of the container 6 and constitutes a heating element of electromagnetic heating. Since aluminum having good heat conductivity is used for the inner layer 8, heat transfer to the cooked product is good. Since the stainless steel of the outer layer 9 of this container is a material having a lower thermal conductivity than aluminum, it has a heat retaining property as compared with the case of aluminum alone. Recently, a container in which the outer periphery of a metal container is coated with a Teflon film containing hollow glass beads is also on the market.

However, in FIG. 3, although ferrite stainless steel is a material having a thermal conductivity of 25 W / mK, which is lower in heat conductivity than aluminum and copper, the clad material used in the container body of the electromagnetic cooker is not shown. The stainless steel outer layer 9 has a thickness of only 0.6 mm or less. This is because the clad material is restricted by the necessity of being capable of being deep drawn and of being lightweight without delamination. Therefore, the heat retention of the container body of FIG. 3 is not sufficient.

[0007] Further, the container body of the electromagnetic cooker on which the Teflon film coating has been performed is insufficient in heat retention because the coating film thickness is as thin as about 0.3 mm. In order to increase the thickness of the Teflon coating film and increase the heat insulation, it is necessary to apply several layers and it is troublesome, and it becomes very expensive. Not appropriate. In order to increase the heat retention of the container body, not only place a material with low thermal conductivity on the outer periphery of the container,
The low thermal conductive material must have sufficient wall thickness for heat insulation. Moreover, the container must be lightweight in order to be an easy-to-use container body.

As described above, it is desired that the container body of the cooker conducts heat to the cooked product well during cooking, while it is desired that the cooker has good heat retention property at the time of warming. In order to prevent cooling, it is desirable to provide a low thermal conductive material on the outer peripheral side of the container having excellent thermal conductivity to enhance the heat retention. However, the conventional technology using cladding material of aluminum and stainless steel or using Teflon coating as a heat insulator on the outside of the container is difficult to process, the weight increase is remarkable, and it is economically inappropriate. Accordingly, there is a problem that a wall thickness effective for keeping heat cannot be sufficiently secured.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and it has a good heat-retaining property and a light weight at the time of warming while providing good heat to a cooked product at the time of cooking. It is an object of the present invention to provide a cooker having a container body which is excellent in economy and a method for manufacturing the cooker.

[0010]

The heat-retaining cooker according to the present invention is characterized in that a metal having excellent heat conductivity is used as a matrix, and a material having a lower specific gravity and a lower heat conductivity than the metal is joined to an outer peripheral portion of the cooker. And at least a part of a joint portion between the container body and the low thermal conductive material is combined to form a container body.

Further, another heat-retaining cooker according to the present invention is characterized in that a metal having excellent heat conductivity is used as a matrix and a material having a lower specific gravity and a lower heat conductivity than the metal is joined to an outer peripheral portion of the cooker. The present invention is characterized in that it has a container body formed by compounding at least a part of a joint portion with a conductive material, and an electromagnetic induction heating element for heating the container body.

FIG. 1 is a schematic sectional view of an embodiment of the container body of the heat-retaining cooker according to the present invention. In FIG. 1, a container body 1 of a heat-retaining cooker has a heat transfer portion 2 made of a metal having excellent heat conductivity in an inner portion of the container, and a heat insulator made of a material having a low specific gravity and a low heat conductivity outside the container. And a heat transfer portion 2 made of a metal having excellent heat conductivity.
And a heat insulating portion 3 made of a material having a low thermal conductivity, a portion 4 in which a metal having excellent thermal conductivity has penetrated into the void portion of the material having a low thermal conductivity, that is, a composite portion 4. I have.
The composite portion 4 may be partially or uniformly composited, but is more preferably inclinedly composited. This combination increases the bonding strength between a metal having excellent thermal conductivity and a material having low thermal conductivity, and does not cause a problem of peeling due to a heat cycle.

In the container body of this cooker, the heat transfer portion 2 inside the container is made of metal having excellent heat conductivity, and transfers the heat from the heating portion to the cooked product efficiently and uniformly. The outer heat retaining section 3 is made of a material having a low specific gravity and a low thermal conductivity, and plays a role of retaining heat. In this container, since the low heat conductive material of the heat retaining section 3 has a low specific gravity, even if it has a thickness of several mm, which is a sufficient thickness for securing the heat retaining property, the weight does not become excessive.

Here, the metal having excellent heat conductivity used as the heat transfer portion 2 in the inner part of the container body of the cooking device of the present invention has a heat conductivity of 100 to 390 W / mK, and can be melted and cast. A metal having a low melting point of as low as 500 to 1065 ° C., such as aluminum or aluminum alloy, copper or copper alloy, which satisfies these conditions and has excellent corrosion resistance, can be suitably used. Therefore, these metals are used as the matrix metal, and the molten metal is subjected to, for example, casting and forging, so that the matrix metal is immersed in the material having a low specific gravity and a low thermal conductivity to produce a composite cooker container body. be able to.

The low specific gravity low heat conductive material forming the heat retaining portion 3 to be joined to the outer periphery of the container body of the cooking device of the present invention preferably has a specific gravity of 0.1 to 4.0, more preferably 0.1 to 4.0.
1 to 1.0, and the thermal conductivity is preferably 4 to 20 W /
mK, more preferably 4 to 10 W / mK. For example, various lightweight ceramics can be used. In particular, those made of natural sand or rock containing a large amount of impurity elements are advantageous in terms of low thermal conductivity and economy.

As the form of the particles constituting the lightweight ceramic, any of particles, fibers, hollow bodies, and porous bodies can be used. Among them, the hollow body is particularly excellent in lightness and low thermal conductivity. A typical example is a shirasu balloon produced from shirasu produced in Kyushu, which can be suitably used.

In order to compound these ceramics and metal, the ceramic material may be formed in advance into a sheet-like or mat-like molded body. When a ceramic material is formed into a molded product, a material obtained by processing ceramic fibers into a woven fabric or a net can be suitably used.

Examples of materials having low specific gravity and low thermal conductivity other than ceramics used in the present invention include Ti, metallic hollow beads, and porous metal bodies subjected to a sealing treatment.

Next, FIG. 2 shows a schematic sectional view of one embodiment of a container body of another heat retaining cooker according to the present invention. In the container body 10 of the heat-retaining cooker of FIG. 2, a heat transfer portion 2 made of a metal having excellent heat conductivity is provided on an inner layer. The outer layer has a heating unit 5 using an electromagnetic induction heating element in addition to the heat retaining unit 3 using a material having a low specific gravity and a low thermal conductivity. The heating unit 5 using an electromagnetic induction heating element
Is a heat insulation part 3 made of low specific gravity and low thermal conductivity material
It may be further covered by. For the heating unit 5 using the electromagnetic induction heating element, use a material that efficiently generates heat by electromagnetic induction, such as a magnetic material such as SUS430 steel or a material having a moderately high electrical resistivity such as a titanium alloy. Can be.

In the present invention, at least a part of the joint between the electromagnetic induction heating element and the metal matrix is provided with the composite part 1.
By forming 1, the bonding reliability can be improved. As a method of compounding the joints, a metal plate of a heat generating material is cast with, for example, an aluminum metal matrix, and at that time, a porous layer is formed on the surface of the metal plate, and the molten matrix metal is formed into a porous layer. A method of infiltrating (JP-A-7-232261) can be used.

As described above, it is advantageous to use a porous electromagnetic induction heating element. As such a porous electromagnetic induction heating element, particles, fibers, porous bodies, woven fabrics of a material having a high electrical resistivity can be used. And a molded article such as a net can be used.

It is also possible to combine the porous body of the heat-generating metal itself to form a heating section. For example, a composite of magnetic metal fibers can be used (“Material” Vo)
l. 38 (1997) No. 1, P12).

Next, the method for manufacturing a heat-retaining cooker according to the present invention comprises the steps of disposing a material having low specific gravity and low thermal conductivity at a predetermined position of an external mold, for example, at a position in contact with the inner surface of the external mold. A step of injecting a predetermined amount of molten metal having excellent thermal conductivity into the mold, and inserting an internal mold into the mold to cast a container body of a heat insulating cooker from the molten metal. It is characterized by having a process.

[0024] Further, another method of manufacturing a heat-retaining cooker according to the present invention includes the steps of:
For example, in the step of arranging a material having a low specific gravity and a low thermal conductivity at a position in contact with the inner surface of the outer mold, in addition to arranging the material having a low specific gravity and a low thermal conductivity, a material for the electromagnetic induction heating element is also specified. At a position, for example, at the bottom of an external mold to manufacture the container body.

In the method of manufacturing a heat-retaining cooker according to the present invention, for example, a pre-formed body of a heat-retaining portion having low thermal conductivity or a heating-portion electromagnetic induction heating element of a container body is set in an external mold in the shape of the container body, A molten metal forging method in which a molten metal of aluminum or a copper alloy is poured therein and an internal mold is inserted into the molten metal to immediately perform pressure molding can be preferably used. In this pressurizing step, the preformed body is sufficiently impregnated with the molten metal, and the container body of the heat retaining cooker in which the compounding is well performed can be manufactured with good reproducibility.

In the method for manufacturing a container body having a heat generating portion according to the present invention, a molded body of a low heat conductive material of a heat retaining portion of the container body and a metal having excellent heat conductivity of a matrix are integrally formed, Next, this and a molded body made of a material having low heat conductivity in the heat retaining section can be integrally molded by means such as casting. However, it is more reasonable to simultaneously form a material having a low thermal conductivity in the heat retaining section and a metal matrix having excellent heat conduction simultaneously with the electromagnetic induction heating element of the heating section, because the process can be shortened and is rational.

According to the method for manufacturing a heat-retaining cooker according to the present invention, since it can be manufactured by casting, the degree of freedom of the shape of the main body container that can be manufactured is wide. Therefore, for example, as shown in the schematic diagrams of FIGS. 1 and 2, a round bottom shape preferable for convection of heat is also possible.

In the method of manufacturing a heat-retaining cooker according to the present invention, a so-called molten metal forging device can be used as equipment when using the molten metal forging method. A die casting machine can be used depending on conditions. Further, if a centrifugal casting device is used, compounding using centrifugal force can be performed.

In the present invention, there is no particular limitation on the thickness of the metal part having excellent thermal conductivity that constitutes the inner part of the container body of the heat-retaining cooker. The metal portion constitutes a heat transfer portion, does not cause liquid leakage as a matrix of the container, has a suitable mechanical strength as a container, and has an appropriate weight. The low thermal conductive material portion in the present invention may be provided with sufficient heat retention for the container and the cooked product, and the thickness thereof is not particularly limited. However, in order to always obtain sufficient heat retention, the thickness of the low thermal conductive material, including the part integrated with the matrix by compounding, may preferably have at least 1 mm, more preferably 3 mm.

In the composite part of the container body of the cooker according to the present invention, a stronger connection can be obtained by inclining the volume ratio of the composite component. The effect can be obtained as long as the metal having excellent heat conduction is firmly bonded to the low heat conduction material or the electromagnetic induction heating element, and the thickness of the composite portion is not particularly limited. In order to obtain a sufficiently stable effect, the thickness of the composite part may desirably be at least 500 μm. Further, when the volume ratio of the composite component is inclined, the composite portion including the inclined portion may reach the outer peripheral portion of the low heat conductive material or the electromagnetic induction heating element layer.

Next, the operation of the present invention will be described. The heat-retaining cooker of the present invention comprises a container body by using a highly conductive metal as a matrix, joining a light-weight, low-thermal-conductivity material to the outside thereof, and partially compounding the joint. Therefore, unlike the simple joining, there is no possibility that the joining portion is separated. Moreover, since the material having a low specific gravity and a low thermal conductivity covers the outer periphery of the container with a sufficient thickness, it is excellent in heat retention and lightweight. Further, since the container body of the heat retaining cooker of the present invention can be manufactured by immersing a highly conductive metal as a matrix by casting, the degree of freedom of the container shape that can be manufactured is wide. Therefore, as shown in the schematic diagram of FIG. 2, a shape having a round bottom and favorable for heat convection is also possible.

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on examples.

(Example) A container body 10 of a heat-retaining cooker whose cross-sectional view is schematically shown in FIG. 2 was manufactured. As a low specific gravity and low heat conductive material used for the heat retaining section 3, a shirasu balloon (a heat-treated shirasu sand into a hollow body) and alumina
Silica fiber and colloidal silica as a binder are mixed at a volume ratio of 3: 1: 0.3, respectively, press-formed using a mold having a shape of a container body, dried, and dried at about 1100 ° C.
To prepare a porous preform having a porosity of 30 to 40%. Next, as an electromagnetic induction heating element, one obtained by stacking three layers of mesh 1000 mesh knitted with SUS430 wire and press-molding it into the shape of the heating unit 5 was prepared.

The outer die of the container body 10 was set in the molten metal forging apparatus, and the above two types of molded bodies were incorporated. A molten JIS AC4CH aluminum alloy at about 750 ° C. was poured into this, and an internal mold was inserted into the molten metal and press-molded into a shape of a main body container for a cooker, thereby forging molten metal. As a result, the heat insulating layer 3 made of ceramics having a thickness of 3 mm and a volume ratio of about 60%, and a SUS43 having a thickness of 1.5 mm were used.
Thus, a container having an electromagnetic induction heating element heating section 5 composed of a 0 net and a heat transfer section 2 composed of an aluminum alloy having a thickness of 2 to 3 mm was obtained.

The overall thickness including the heat transfer section 2 is 3.5 to
4.0 mm, and the total weight was almost the same as that of a conventional clad container having the same cooking amount. The thermal conductivity of the composite material having a volume ratio of 60% of this embodiment is about 50 W / mK, which is a SUS430 of a 0.6 mm thick clad material.
Heat retention was as high as about 2.5 times the heat transfer resistance of the layer. In addition, stable heat generation characteristics were obtained as an electromagnetic induction heating element.

Further, by this manufacturing method, the shape of the container body can be formed into a round bottom shape of a furnace pot shown in FIG. 2, and furthermore, it can be integrally formed simultaneously with the step of forming the heat retaining portion. It was confirmed that it had excellent properties.

[0037]

As described in detail above, the heat-retaining cooker of the present invention has a container body formed by joining a material having low specific gravity and low thermal conductivity to the outer periphery of a container made of metal having excellent heat conductivity. Therefore, the thickness of the heat retaining portion made of a low thermal conductive material can be sufficiently ensured, and it is lightweight and easy to use. In addition, the metal having excellent thermal conductivity inside the container and the low thermal conductive material outside have a composite part and are firmly bonded to each other, and there is no fear of delamination, so that the reliability is high.

By having the electromagnetic induction heating element, it is possible to provide an electromagnetic cooker that is lightweight and has excellent heat retention. In addition, since relatively inexpensive materials can be used and can be manufactured using general manufacturing equipment, the cost is excellent.

Further, in the heat-retaining cooker of the present invention, the container body can be manufactured by casting by using a metal having excellent heat conductivity as a matrix and compounding it with a low heat-conductive material. High degree of freedom of possible container shape. For example, it is possible to mold an electric kettle with a round bottom shape similar to that of a traditional furnace, so it can be applied to a wide variety of applications, such as the fact that the same round bottom shape as the furnace is suitable for heat convection. .

[Brief description of the drawings]

FIG. 1 is a view showing a container body of a heat-retaining cooker according to one embodiment of the present invention.

FIG. 2 is a view showing a container main body of the heat retaining cooker according to one embodiment of the present invention.

FIG. 3 is a view showing an example of a container body of a conventional electromagnetic cooker.

[Explanation of symbols]

1, 10: container body, 2: heat transfer section (metal with excellent thermal conductivity), 3: heat retaining section (lightweight, low heat conductive material), 4: composite section, 5: heating section ( Electromagnetic induction heating element), 6: container body, 7: clad plate, 8: inner layer, 9: outer layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI B32B 15/01 B32B 15/01 Z 18/00 18/00 B

Claims (9)

[Claims] 1. A metal having excellent thermal conductivity is used as a matrix, and a material having a lower specific gravity and a lower thermal conductivity than the metal is joined to an outer peripheral portion, and at least a part of a joint between the metal and the material having a low thermal conductivity is provided. A heat-insulating cooker comprising a container body obtained by compounding the above. 2. The heat-retaining cooker according to claim 1, wherein the material having a lower specific gravity and a lower thermal conductivity than the metal to be joined to the outer peripheral portion of the container body is ceramic. 3. The thermal insulation according to claim 1, wherein the metal which is a matrix of the container body and has excellent thermal conductivity is at least one of copper, copper alloy, aluminum and aluminum alloy. Sex cooker. 4. A metal having excellent thermal conductivity is used as a matrix, and a material having a lower specific gravity and a lower thermal conductivity than the metal is joined to an outer peripheral portion, and at least a part of a joint between the metal and the material having a low thermal conductivity is provided. And an electromagnetic induction heating element for heating the container body. 5. The heat retaining cooker according to claim 4, wherein the electromagnetic induction heating element is cast into the matrix of the heat retaining cooker container body. 6. The thermal insulation according to claim 4, wherein at least a part of a joint between the electromagnetic induction heating element and a metal constituting an inner part of the container body is compounded. Sex cooker. 7. The electromagnetic induction heating element is formed by impregnating at least one of particles, fibers, a porous body, a woven fabric and a net of a material having a high electrical resistivity with the matrix. The heat-retaining cooker according to any one of claims 4 to 6. 8. A step of disposing a material having low specific gravity and low thermal conductivity at a predetermined position of an external mold, and injecting a predetermined amount of molten metal having excellent thermal conductivity into the mold. And a step of inserting an internal mold into the mold and casting the container body of the heat-insulating cooker from the molten metal. 9. A step of disposing a material having a low specific gravity and a low thermal conductivity and a material of an electromagnetic induction heating element at a predetermined position of an external mold, and providing a predetermined amount of heat conductivity in the mold. A step of injecting a molten metal, and a step of inserting an internal mold into the mold and casting a container body of the heat-insulating cooker from the molten metal. .