JPH0896946A - Electromagnetic cooking pan - Google Patents

Abstract

PURPOSE: To increase the heating value, and to improve the heating efficiency by using titanium or titanium alloy as the metal material forming the inner surface layer of a pan, and furthermore, using magnetic metal material as the metal material forming the outer surface layer of the pan. CONSTITUTION: A pan main body 10 is formed into the double-layer structure of clad, and the pan inner surface layer 1 is made of titanium or titanium alloy, and the pan outer surface layer 2 is made of magnetic metal material such as magnetic stainless steel. The surface of the inner surface layer 1 is formed with a film 3 such as titanium oxide film or titanium nitride film at need. Since this titanium oxide film does not need the film coating or the special heating, the pan main body 10 can be manufactured by superplastic processing or hoot forging. This titanium or titanium alloy has the performance for appropriately relaxing the heat conduction to the food, and furthermore, since it has a small heat conductivity and a small density, it is appropriate for the material forming the inner surface layer. Furthermore, titanium and titanium alloy is a heater, which receives the induction heating work by the high frequency current and which heats efficiently, it is excellent for the metal material forming the outer surface layer 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pot used for an electromagnetic cooker.

[0002]

2. Description of the Related Art The principle of heat generation by an electromagnetic cooker is that a high-frequency current is passed through an induction coil placed under the plate of the electromagnetic cooker to generate an alternating magnetic field, and an eddy current is generated in a pan placed on the plate. Shed. This eddy current changes into Joule heat according to the specific electric resistance of the pot body, causing the pot body to generate heat.
Therefore, it is possible to cook various foods such as cooked rice, stir-fried foods, fried foods, and simmered foods with the electromagnetic cooker.
Moreover, it is safe and clean because it does not emit flames. In addition, since it directly heats the pot, it has high thermal efficiency and is rapidly spreading due to the recent social situation and convenience of energy saving.

As a pan for such an electromagnetic cooker, a non-magnetic material such as aluminum or copper has a low electric resistance and a small amount of heat generation.
As shown in Japanese Patent Publication No. 18, the inner surface of the pan is made of aluminum,
A clad pan made of stainless steel is widely used on the outer surface of the pan. Here, in this specification,
The clad pan refers to a pan having two or more material layers in which the material forming the pan body is a composite of two or more different metal materials. In addition, as for the structure of two or more layers, there is no problem if it is composited even if not bonded. The joining method and the composite method are not particularly limited. Further, in the following, when describing the constituent material of the clad pot, first write the material name that constitutes the inner layer of the pot, then the material name of the intermediate layer, and finally the material name of the outer layer of the pot, Each is represented by a slash mark. In the above example, it is represented as aluminum / stainless steel, indicating that it is a two layer composite material layer.

In a conventional pan for an electromagnetic cooker, an iron pan has a large amount of heat radiated from the side surface, so that the range of dishes that can be appropriately cooked is extremely limited and the weight is large. On the other hand, an aluminum / stainless steel clad pan is lighter in weight than an iron pan, but has been confirmed to be inferior in calorific value and heat generation efficiency, and the cooking range is narrow. There is.

[0005]

As described above, the conventional pot for the electromagnetic cooker is not designed and manufactured in consideration of the principle of heat generation of the electromagnetic cooker, and has a structure in which proper heating and cooking cannot be performed. ing. That is, in cooking with an electromagnetic cooker, unlike conventional gas fires or sheath heaters, the pan itself directly generates heat rapidly due to electromagnetic induction, and the heat is transmitted to the food without being relaxed. Defects such as impairing the flavor and causing the food to become crispy are apparent depending on the type, and thus have an aspect that is not suitable for a wide range of cooking. In particular, it is difficult to select the constituent material and the plate thickness of a clad pan, and so far, it has often been done by trial and error.

In view of the present situation and the conventional problems, the present inventors calculated the heat generation amount based on the magnetic flux distribution and eddy current distribution inside the pan based on the magnetic field analysis, and optimized the constituent material. And, we have repeatedly examined the plate thickness. The present invention is based on the findings from the results of this study, and has a large amount of heat generation, high heat generation efficiency, and excellent thermal conductivity relaxation, and a lightweight electromagnetic cooker pot suitable for wide range cooking. It is intended to be provided.

[0007]

According to the present invention, in a clad pan for an electromagnetic cooker, the metal material forming the inner surface layer of the pan is titanium or a titanium alloy, and the metal material forming the outer surface layer of the pan is The above problem is solved by providing a pan for an electromagnetic cooker characterized by being a magnetic metal material.

A preferred embodiment of the present invention is a combination in which the metal material of the inner surface layer of the pan is titanium or a titanium alloy, and the metal material of the outer surface layer of the pan is magnetic stainless steel.

Regarding the thickness of the pot, the thickness of the metal material of the outer surface layer of the pot is 0.1 to 3.0 mm. Moreover, the thickness of the metal material of the inner surface layer of the pan is set to 0.1 to 3.0 mm. In this case, the total thickness of the pan is 1.0 to 4.0 mm.

According to a further preferred embodiment, an intermediate layer for relaxing heat conduction is provided between the inner surface layer of the pan and the outer surface layer of the pan.
In particular, duplex stainless steel or copper-nickel alloy is suitable as the material for relaxing the heat conduction.

The inner surface of the pot is coated with a titanium oxide film, a titanium nitride film or a tetrafluoride resin layer.

[0012]

[Function] In a clad pan for an electromagnetic cooker, the outer surface layer of the pan mainly constitutes a heating element that generates heat due to the electromagnetic induction effect of the electromagnetic cooker, and the inner surface layer of the pan moderately transfers heat from the heating element. It is necessary to relax and tell the ingredients.
As the constituent materials of the clad pan, Table 1 shows possible candidate materials, focusing on the physical properties of density, thermal conductivity, volume resistivity, and relative permeability.

[0013]

[Table 1]

Among the materials shown in Table 1, those having a relative magnetic permeability of 1 are unsuitable as a heat generating material for the outer surface layer of the pot, so Cu
-10% Ni, nickel silver, Ti, Ti alloy, Al and SU
Non-magnetic stainless steel such as S304 and SUS321 are excluded. Further, even in a magnetic metal material having a relative magnetic permeability of more than 1, Fe has a low volume resistivity and thus has a low heat generation efficiency.
Also easy to rust. The 42-6 alloy and the 42 alloy have a large density and therefore a large weight. Therefore, as a heat generating material for the outer surface layer of the pan, a magnetic metal material, especially SUS430 or SU
Magnetic stainless steel such as S329J1 is suitable.

Next, the material for the inner surface layer of the pot is required to have a property of relaxing heat conduction. Therefore, aluminum and iron having extremely high thermal conductivity are not preferable. Therefore, it is better to have a low thermal conductivity to some extent,
The smaller the density, the better. From this point, titanium and titanium alloy are most suitable as the material for the inner surface layer of the pot.

The thermal conductivity of the metal material of the inner layer of the pot is
1 to 50 W / mK is suitable. When it is less than 1 W / m · K, not only the thermal conductivity is poor, but rather the cooking takes a long time, the cooking efficiency is deteriorated, and the flavor may be impaired depending on the dish. Further, when the thermal conductivity exceeds 50 W / m · K, the effect of relaxing the heat on the outer surface layer of the pan that is rapidly heated by electromagnetic induction to a high temperature becomes small, and cooking in a wide range becomes difficult.

The plate thickness range of the inner surface layer of the pan and the outer surface layer of the pan are set to 0.1 to 3.0 mm, not only from the viewpoint of heating efficiency, but also from the viewpoint of cooking workability in terms of weight and availability of materials. It is specified in consideration of the cost aspect from manufacturability. Although the total plate thickness range of the pan is set to 1.0 to 4.0 mm based on the above request, it is mainly defined as a practical pan plate thickness range.

The pan for the electromagnetic cooker of the present invention is not limited to the one made of clad having a two-layer structure. There is no problem even if the cladding is made of three or more layers.
In this case, the intermediate layer between the inner surface layer of the pan and the outer surface layer of the pan should be selected in combination with the material having the thermal conductivity relaxation property of the inner surface layer of the pan. The duplex stainless steel or copper-nickel alloy has a thermal conductivity similar to that of the magnetic stainless steel of the pan outer surface layer that controls the heat generation, and as shown in the results of Examples (Tables 2 and 3), good results are obtained. Is getting

The titanium oxide film, titanium nitride film, or tetrafluoride resin layer that covers the surface of the inner surface layer of the pot is for improving the stickiness of food materials. In particular, the titanium oxide film and titanium nitride film are tetrafluoride. It is stronger than the resin layer and has a long-awaited surface quality especially for commercial pots.

[0020]

【Example】

Example 1. FIG. 1 is a cross-sectional side view of a pan for an electromagnetic cooker according to a first embodiment of the present invention, in which a part is shown enlarged. The pan body of this embodiment, which is designated by the general reference numeral 10, is made of a clad having a two-layer structure, and the pan inner surface layer 1 is, for example, a titanium alloy, and the pan outer surface layer 2 is, for example, magnetic stainless steel. Further, an appropriate film 3 is applied to the surface of the inner pot layer 1 as required. In this embodiment, a titanium oxide film or a titanium nitride film is formed, and the titanium oxide film or the titanium nitride film is formed by heating the pan body 10 during the forming process or cooking. Unlike the tetrafluoride resin layer, the titanium oxide film and the titanium oxide film do not require film coating treatment or special heat treatment. Such a clad pan body 10 can be made by superplastic working or hot forging.

As described above, the metal material forming the inner surface layer 1 of the pot needs to have a property of moderately relaxing the heat transfer to the food material. All materials except white, pure Al and Fe are targeted. Among them, titanium and titanium alloys are the most preferable materials because of their low thermal conductivity and low density.

Since the metal material forming the pan outer surface layer 2 must be a heating element that efficiently generates heat by receiving an induction heating action by a high frequency current of an electromagnetic cooker (not shown), a magnetic metal material having a high specific electric resistance as much as possible. To use.

Generally, the penetration depth of eddy current is δ = k (ρ
/ Μf) ^1/2 (m) Here, δ is the penetration depth (m) of the eddy current, ρ is the volume resistivity (μΩm), μ is the relative permeability, f is the coil current frequency (Hz), and k is a constant. Therefore, the penetration depth δ of the eddy current flowing in the metal due to electromagnetic induction depends on the ratio of the volume resistivity ρ of the metal itself to the relative permeability μ, ρ / μ, and the penetration depth increases as this value increases. It gets deeper. When the value of ρ / μ is extremely small, it is necessary to make the thickness of the magnetic metal material of the outer surface layer of the pan considerably thin from the viewpoint of heating efficiency, and in addition to the problem from the manufacturing cost of the pan, the purpose of relaxing heat Since the difference in thickness between the inner surface layer of the pan and the metal becomes large, the cooking efficiency deteriorates. On the other hand, when the value of ρ / μ is large, the plate thickness becomes thicker from the viewpoint of heat generation efficiency, and the weight of the pan increases, so that the cooking workability is deteriorated particularly when cooking with one hand such as a frying pan. For these reasons, among the materials shown in Table 1, magnetic stainless steel is preferable as the material for the pan outer surface layer 2.

Examples of magnetic stainless steels include ferritic stainless steels (SUS430, 405, 410).
L, 429), duplex stainless steel (SUS329
J1, 329J2L, etc.) and martensitic stainless steel (SUS403, 410, 420J1, etc.).

Table 2 shows the relation between the constituent materials of the pot and the calorific value obtained by the magnetic field analysis. In addition, a comparative example is also shown. Then, in order to verify the validity of the magnetic field analysis results, a pot was actually prototyped based on the magnetic field analysis data, and the thermal efficiency of the prototype pot was measured according to the "Technical Standards for Electrical Parts" prescribed by the Japan Electrical Association. Comparison with the analysis results showed that there was almost no difference between the two. The model used in the magnetic field analysis is
In consideration of versatility, the outer diameter is 220 mm and the height is 180 mm. On the other hand, for the coil, refer to the 5 kW commercial electromagnetic cooker, and use a copper wire with a diameter of 5 mm for an outer diameter of 260 mm and an inner diameter of 40 mm.
The doughnut shape was used, and an alternating current (45 Arms × 22 turns) having a driving frequency of 25 kHz was uniformly applied to the donut shape.

[0026]

[Table 2]

In addition, FIG. Ti-6A of 1
It is a graph of the result of having investigated the change of the calorific value with respect to the clad pan made of 1-4V / SUS430 according to the board thickness of SUS430 of a pan outer surface layer.

Further, Table 3 summarizes the test results in which the cooking performances of typical prototype pots were actually variously cooked and the cooking performances of the pots were compared. In Table 3, the symbol ⊚ indicates the best, the symbol ◯ indicates good, the symbol Δ indicates slightly unacceptable, and the symbol x indicates unacceptable.

[0029]

[Table 3]

As can be seen from the magnetic field analysis results in Table 2, the sample No. 1 to No. For all 11
Both the calorific value and the exothermic efficiency show high values.
Sample No. In No. 1, the calorific value near the output of the electromagnetic cooker is obtained by optimizing the plate thickness of the constituent materials. Moreover, sample N
o. Other than 4, the pot weight is also lighter. It should be noted that an unnecessarily thick plate not only increases the weight of the pan, but also has a negative effect on heat generation efficiency. On the other hand, the clad pans of aluminum / nickel white, aluminum / iron, and aluminum / stainless steel (Sample Nos. 12 to 14) shown in the comparative examples are generally inferior in calorific value and exothermic efficiency. The point that the pan weight becomes particularly heavy is noticeable. Sample No.
The Ti-6Al-4V alloy simple substance pot of No. 16 was introduced in Nikkei Material & Technology 94.7 (No. 143, page 44), but the heating efficiency of the example was much higher, and It is clear that it is a high-performance pot for an electromagnetic cooker. Sample No. No. 4 has the highest pot weight, but this is because the influence of the thickness of Cu-10% Ni in the intermediate layer is great.

Sample No. No. 4 is a 4-layer clad pan, sample No. 5 is a 3-layer clad pan.
FIG. 3 is a sectional view showing a three-layer clad ladle, and 4 is an intermediate layer. Cu-10% N of the intermediate layer 4 used in Table 2
i, Duplex stainless steel works together with titanium or titanium alloy of the inner surface layer 1 of the pot as a material for relaxing heat conduction. This is clear from the point that it has a heat generation amount and heat generation efficiency comparable to those of other two-layer structures. However, the combination of titanium / magnetic stainless steel and titanium alloy / magnetic stainless steel has many advantages.

The advantage that the inner surface layer of the pot is titanium or a titanium alloy has a thermal conductivity of 5 to 17 W / m · K.
Because of this, it can be cooked in a wide range, and because it is lightweight, it has good operability, and because it forms a titanium oxide film and titanium nitride film, it does not cause the food material to become sticky. Also,
The advantage of the outer surface layer of the pan being magnetic stainless steel is that the efficiency of heat generation increases and the depth of eddy current penetration is shallow, so it is possible to reduce the thickness of the outer surface layer of the pan without reducing the efficiency of heat generation, and it is lightweight. It can be converted to rust and does not cause rust.

It can be seen from FIG. 2 that the calorific value changes depending on the thickness of the pan outer surface layer. In the case of SUS430, the maximum calorific value is shown when the thickness is 0.3 mm, 3.0 mm
Also shows a fairly high calorific value. The lower limit of the outer layer thickness of the pan of the present invention, 0.1 mm, is mainly due to the production limit of the clad pan.

As is clear from the results shown in Table 3, the cookable range of this example is much wider. This is because the inner surface layer of the pan has a function of relaxing heat conduction as described above. In particular, the titanium or titanium alloy on the inner surface layer of the pan slows down the temperature rise during cooking and heating in a high temperature range, so that a wide range of cooking can be performed. In addition, it is lighter in weight than conventional pots for electromagnetic cookers, has good workability in cooking, and has excellent heat retention. Further, in the clad ladle of the present embodiment, since the metal of the inner surface layer of the pot is titanium or titanium alloy, a titanium oxide film or a titanium nitride film is formed on the surface, and foodstuffs are unlikely to crumble to the pot. This is one of the major characteristics.

Example 2. Table 4 shows the sample No. of Table 1. 1 shows the heat generation amount, heat generation efficiency, and weight when the plate thickness of the inner and outer surface layers was changed based on the magnetic field analysis data.

[0036]

[Table 4]

As can be inferred from the results of FIG. 2, as the plate thickness of the pan outer surface layer becomes smaller, the amount of heat generation decreases and the heat generation efficiency also decreases. The thickness of the inner layer of the pot has little relation to the amount of heat generated,
It exclusively affects the thermal conductivity relaxation performance.

[0038]

As described above, according to the present invention,
In a clad pan for an electromagnetic cooker, the inner surface layer of the pan is titanium or a titanium alloy, and the outer surface layer of the pan is a magnetic metal material, so the thermal conductivity of food materials is good, and high-efficiency and wide-range cooking is possible. It is also lightweight and has excellent workability in cooking.

In particular, the above effect can be further improved by forming the outer surface layer of the pan from magnetic stainless steel.

Since the thickness of the outer layer of the pan is related to the amount of heat generation, and the thickness of the inner layer of the pan is related to the thermal conductivity relaxation property, the above effects can be obtained by defining these thicknesses within a predetermined range. There is.

The use of duplex stainless steel or copper-nickel alloy in the intermediate layer between the inner surface layer of the pan and the outer surface layer of the pan has the effect of mitigating heat conduction.

Since the titanium oxide film and the titanium nitride film that coat the surface of the inner surface layer of the pot are stronger than the tetrafluoride resin, they exhibit a great effect particularly in commercial pots under severe working conditions.

[Brief description of drawings]

FIG. 1 is a cross-sectional side view of a pan for an electromagnetic cooker according to the present invention.

FIG. 2 is a graph showing the relationship between the plate thickness of the pan outer surface layer and the amount of heat generated.

FIG. 3 is a cross-sectional view of a clad pan for a three-layer electromagnetic cooker.

[Explanation of symbols]

1 inner pot layer, 2 outer pot layer, 3 film, 4 middle layer,
10 Pan body.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kimio Hashizume 2-3-3 Marunouchi, Chiyoda-ku, Tokyo Sanryo Electric Co., Ltd. (72) Inventor Osamu Makino 2-3-2 Marunouchi, Chiyoda-ku, Tokyo In Ryo Electric Co., Ltd. (72) Inventor Mikio Watanabe 8-1-1 Tsukaguchi Honcho, Amagasaki City, Hyogo Sanryo Electric Co., Ltd. Inside Material Device Research Center (72) Inventor Yasuhiro Shiraki 8-1-1 Tsukaguchi Honcho, Amagasaki City, Hyogo Prefecture No. 1 Sanryishi Electric Co., Ltd. Material Devices Research Laboratory (72) Inventor Masami Hotta 1-2-22-11 Shinkawa, Chuo-ku, Tokyo Kinosauchi Co., Ltd. (72) Nobuhiro Okubo 1-5, Kyobashi, Chuo-ku, Tokyo No. 8 Nihon Yakin Kogyo Co., Ltd. (72) Inventor Hiroshi Yoshida 4-2 Kojimacho, Kawasaki-ku, Kawasaki-shi, Kanagawa Nihon Metallurgical Industry Co., Ltd. (72) Inventor, Tatsuo Katagiri, 1-5-8, Kyobashi, Chuo-ku, Tokyo Inside Nippon Yakin Kogyo Co., Ltd.

Claims (11)

[Claims] 1. A clad pan for an electromagnetic cooker, wherein the metal material forming the inner surface layer of the pan is titanium or a titanium alloy, and the metal material forming the outer surface layer of the pan is a magnetic metal material. A pan for an electromagnetic cooker. 2. A clad pan for an electromagnetic cooker, wherein the metal material forming the inner surface layer of the pan is titanium or a titanium alloy, and the metal material forming the outer surface layer of the pan is magnetic stainless steel. A pan for an electromagnetic cooker. 3. The thickness of the metallic material of the outer surface layer of the pan is 0.1 to 0.1.
The pan for an electromagnetic cooker according to claim 1 or 2, wherein the pan is 3.0 mm. 4. The thickness of the metal material of the inner surface layer of the pan is 0.1 to 10.
The pan for an electromagnetic cooker according to claim 1 or 2, wherein the pan is 3.0 mm. 5. The pan for an electromagnetic cooker according to claim 1, wherein the total thickness of the pan is 1.0 to 4.0 mm. 6. An intermediate layer for relaxing heat conduction is provided between the inner surface layer of the pan and the outer surface layer of the pan.
The pan for an electromagnetic cooker according to any one of 1. 7. The thermal conductivity between the inner surface layer of the pan and the outer surface layer of the pan is 1
The pan for an electromagnetic cooker according to any one of claims 1 to 6, further comprising an intermediate layer in the range of -50 W / mK. 8. The pan for an electromagnetic cooker according to claim 7, wherein the intermediate layer is a duplex stainless steel. 9. The pan for an electromagnetic cooker according to claim 7, wherein the intermediate layer is a copper-nickel alloy. 10. The electromagnetic cooking according to any one of claims 1 to 9, wherein the surface of the inner surface layer of the pan is coated with at least one kind of titanium oxide film and titanium nitride film. Skillful pot. 11. The pan for an electromagnetic cooker according to claim 1, wherein the surface of the inner surface layer of the pan is covered with a tetrafluoride resin layer.