JP2006247065A - Composite material and manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the joining strength of a composite material favorably used as an electromagnetic cooker and the like. <P>SOLUTION: This composite material is so constituted as to interpose a copper plate between a magnetic metal plate and a non-magnetic metal plate, interpose a cushion metal plate composed of a metal softer than the magnetic metal plate and the copper plate between the magnetic metal plate and the copper plate, and join them together by a hot press. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a composite material and a method for producing the same, and more particularly, it has excellent thermal conductivity and a uniform temperature distribution, and is press-worked and is suitable as a material for forming an inner pot of an electromagnetic induction heating rice cooker or a pan for an electromagnetic cooker. It is used for.

Conventionally, an inner pot of an IH jar rice cooker, a pan for an electromagnetic cooker, and the like are formed of a metal composite material. For example, a clad material of a magnetic metal plate such as stainless steel or iron serving as a heat generation layer and a non-magnetic metal plate such as aluminum serving as a heat transfer layer is formed by drawing and pressing, and the outer surface side is induced as the magnetic metal plate. Electromagnetic induction heating is performed facing the coil.
In many cases, the clad material is formed by laminating the non-magnetic metal plate and the magnetic metal plate by roll rolling. Further, a fluororesin layer is provided on the surface of the non-magnetic metal plate such as the aluminum plate to prevent sticking.

  Since the magnetic metal plate such as stainless steel or iron serving as the heat generating layer has a low thermal conductivity, the bottom wall of the container such as the inner pot or pan facing the induction coil is heated, but the temperature of the side wall is low, and the entire container There is a problem that the temperature distribution of the container is difficult to be uniform and it is difficult to uniformly heat the food in the container. This problem can be improved to some extent by laminating a non-magnetic metal plate such as an aluminum plate having a high thermal conductivity and a heat transfer layer on the magnetic metal plate to form a composite material. Although it is not sufficient, it is desired that the side walls also conduct heat more quickly, and the temperature between the bottom wall and the side walls is uniform.

  In order to solve the above problem, the applicant previously disclosed in Japanese Patent Laid-Open No. 9-129362 (Japanese Patent No. 3594151) a laminated structure of a magnetic metal plate such as a stainless steel plate, a copper plate, and an aluminum plate. A copper plating layer is provided on the joint surface between the copper plate and the copper plate via a nickel plating layer, the copper plate is sandwiched between the copper plating layers and laminated, and each layer is hot-pressed in the laminated state. The structure is integrated by joining.

  When a copper layer having copper plating layers on both sides of the copper plate is interposed between the stainless steel plate and the aluminum plate, the thermal conductivity can be increased and the temperature of the bottom wall and the side wall can be made uniform. Can do. In addition, since the metal laminated by roll rolling is not integrated, it is integrated by hot pressing, so there is little variation in the thickness of the composite material, and therefore wrinkles, cracks, and delamination do not occur during press processing It has advantages.

  As described above, by interposing the copper plate between the stainless steel plate and the aluminum plate, the above-described thermal conductivity and temperature distribution can be made uniform, but the stainless steel plate and the copper plate are difficult to join, and the nickel plating layer and When joining a stainless steel plate and a copper plate with a hot press through a copper plating layer, it turned out that there is room for improvement in order to obtain sufficient joining strength which can endure press work.

JP-A-9-129362

  The present invention has been made in view of the above problems, and improves the thermal conductivity between a magnetic metal plate such as a stainless steel plate constituting a heating layer and a non-magnetic metal plate such as an aluminum plate constituting a heat transfer layer. In the case of a structure in which a copper plate is interposed in order to make the temperature distribution uniform, it is an object to obtain sufficient bonding strength when the laminated metal plates are integrated by hot pressing. .

  In order to solve the above-mentioned problems, the present inventors have repeated intensive experiments. As a result, when a metal is interposed between a magnetic metal plate such as a stainless steel plate and a copper plate softer than these metals, the bondability with the copper plate is improved. I found that it can be improved.

The composite material of the present invention made based on the above knowledge is
A copper plate is interposed between the magnetic metal plate and the non-magnetic metal plate,
The magnetic metal plate and the copper plate are joined via a cushion metal plate made of a metal having a hardness lower than that of the magnetic metal plate and the copper plate.

In the present invention, as described above, a metal plate that is soft and excellent in cushioning properties is interposed between a magnetic metal plate such as a stainless steel plate that is difficult to bond and a copper plate at a hot-pressing temperature than these stainless steel plate and copper plate. Yes.
With this configuration, when these metal plates are laminated and integrated by hot pressing, the magnetic metal plate and the copper plate are easily joined by being pressed through a soft cushion metal plate at the hot pressing temperature, and stainless steel is used. The bonding strength between the magnetic metal plate such as a plate and the cushion metal plate and between the cushion metal plate and the copper plate increases.
In particular, it is preferable to join the cushion metal plate and the magnetic metal plate via a copper plating layer. With this configuration, the copper plating layer between the magnetic metal plate and the cushion metal plate is pressed at a melting point or lower (200 to 300 ° C.) during hot pressing, so that the copper layers are diffusion-bonded to each other. Can be increased,

  As the magnetic metal plate, stainless steel is most suitable, but iron, nickel, cobalt, alloys thereof, and the like can also be used. As the non-magnetic metal plate, an aluminum plate made of an alloy aluminum plate or a pure aluminum plate is most suitable, but any material that is softer and superior in cushioning at a hot pressing temperature than a stainless steel plate or a copper plate may be used. it can.

  Thus, when an aluminum plate is used as the cushion metal plate, there is an advantage that the plating is easily attached stably, the heat conductivity is not impaired, and the weight is light.

In the composite material of the present invention, preferably, the magnetic metal plate is a stainless steel plate, the cushion metal plate is a first aluminum plate made of an alloy aluminum plate or a pure aluminum plate, and the nonmagnetic metal plate is made of a second aluminum plate,
The stainless steel plate, the first aluminum plate, the copper plate, and the second aluminum are laminated, and a copper plating layer is interposed between at least one of the stainless steel plate and the first aluminum plate and between the first aluminum plate and the copper plate.

  The first aluminum plate serving as the cushion metal plate and the second aluminum plate functioning as the heat conductive layer on the surface side may be either a pure aluminum plate or an aluminum alloy plate. When the second aluminum plate disposed on the front side is an aluminum alloy plate, it is preferable to use an Mg—Mn-based aluminum alloy plate because of excellent corrosion resistance.

When providing a copper plating layer on the surfaces of the stainless steel plate and the first and second aluminum plates, it is preferable to provide the copper plating after first providing the nickel plating layer. Thus, when a nickel plating layer is provided in the lower layer of a copper plating layer, a copper plating layer can be stably attached to an aluminum plate and a stainless steel plate, and the adhesion amount can be increased.
Furthermore, it is more preferable that the nickel plating layer is provided on the surfaces of the first and second aluminum plates after the zinc substitution plating process is performed on the lower layer of the nickel plating layer. The thickness of the zinc substitution plating layer is preferably 0.1 μm or less.

A fluororesin layer is provided on the surface of the second aluminum plate opposite to the bonding surface with the copper plate.
Non-adhesiveness can be improved by providing the fluororesin layer, and when the composite material is pressed and molded as a container such as an inner pot or a copper pan, by positioning it on the inner surface side of the container, A function to prevent sticking of the food can be added.
The thickness of the fluororesin layer is 5 to 150 μm, preferably 10 to 50 μm.

The thickness of the copper plate is 0.03 mm to 10 mm, the thickness of the stainless steel plate is 0.05 mm to 10 mm, the thickness of the first and second aluminum plates is 0.10 mm to 10 mm, and the thickness of the copper plating layer is 1-50 μm,
The total thickness of the laminated and integrated plate is preferably 0.3 to 40 mm.
The thicknesses of the copper plate, stainless steel plate, aluminum plate, and copper plating layer are preferably set in the following ranges from the viewpoints of workability, economy, and thermal conductivity. That is,
The thickness of the copper plate is preferably 0.05 to 5.0 mm, most preferably 0.1 to 1.0 mm.
The thickness of the stainless steel plate is preferably 0.1 to 5 mm, and most preferably 0.5 mm.
The plate thickness of the first and second aluminum plates is preferably 0.5 mm to 1.5 mm, most preferably 0.8 mm to 3 mm.
The thickness of the copper plating layer is preferably 2 to 20 μm.

Further, the composite material of the present invention includes the stainless steel, the first aluminum plate, the copper plating layer, the copper plate, the copper plating layer, and the second aluminum plate, and the bonding strength of each of the laminated portions is 5 kgf / If it is 5 mm or more, it does not peel off even when forming a container such as an inner pot of an electromagnetic induction heating rice cooker or a pot for electromagnetic cooking, and is at a practical level. More preferably, it is 10 gf / 5 mm or more.
The bonding strength was measured by cutting the composite material into a strip shape having a width of 5 mm and applying a tensile force in the peeling direction to the bonded portion.

More specifically, the composite material of the present invention, in order from one surface side to the other surface side, the stainless steel plate, nickel plating layer, copper plating layer, nickel plating layer, first aluminum plate, nickel plating layer, copper plating layer, A structure in which a copper plate, a copper plating layer, a nickel plating layer, a second aluminum plate, and a fluororesin layer are laminated is preferable.
A zinc replacement plating layer may be further interposed between the first and second aluminum plates and the nickel plating layer.
Moreover, when using it as the raw material of the inner pot of a rice cooker, you may provide corrosion-resistant metal layers, such as chrome plating, chromate treatment coating | cover, galvanization, on the non-joining surface (outer surface) of a stainless steel plate.

Secondly, the present invention provides a method for producing the above-described composite material.
A typical manufacturing method of the present invention uses stainless steel as a magnetic metal plate, uses a first aluminum plate as a cushion metal plate, uses a second aluminum plate as a nonmagnetic metal plate,
The stainless steel plate, the first aluminum plate, the copper plate, and the second aluminum plate are laminated in order and integrated with a hot press.
In particular, the copper plating layer is provided in advance on the joint surface of at least the first aluminum plate of the stainless steel plate, both surfaces of the first aluminum plate and the joint surface of at least the copper plate of the second aluminum plate,
The stainless plate, the first aluminum plate, the copper plate, and the second aluminum plate are preferably integrated by hot pressing in a state where they are sequentially laminated.

As the hot pressing method, a hot-shaft pressing method, a hot isostatic pressing method, or the like can be adopted, but a hot-shaft pressing method is preferably used. In the hot uniaxial pressing method, the metal plates are sequentially stacked and inserted into a die composed of a mortar and a pestle, and these are joined by hot-axial pressing. In addition, when a plurality of metal plates such as four are taken as a set, each of the plurality of sets is stacked and inserted into a mold, and simultaneously hot pressed, a plurality of composite materials can be mass-produced simultaneously.
The conditions for hot pressing by hot uniaxial pressing are usually a temperature of 200 to 300 ° C., a pressure of 200 to 1000 kg / cm ² , and a pressing time of 10 minutes to 3 hours. The atmospheric conditions are preferably reduced in an inert gas or reduced to a vacuum of 10 torr or less because oxide film formation at the bonding interface can be suppressed.
When the metal plates laminated by the hot press are integrally joined, the joining surface can be firmly joined by metal diffusion of the joining metal layer (plating layer) between the metal plates laminated under heating, compared with roll rolling, And there exists an advantage which can reduce the variation in plate | board thickness.

When providing a copper plating layer on the stainless steel plate and the aluminum plate, as described above, it is preferable to provide a nickel plating layer as a lower layer and a copper plating layer on the surface of the nickel plating layer. Moreover, it is preferable to provide a zinc substitution plating layer in the lower layer of the nickel plating layer in the aluminum plate.
In addition, although the copper plating layer is provided in the joining side surface of the said metal plate laminated | stacked and the nickel plating layer and the zinc plating layer are further provided as needed, these metal layers for joining are replaced with plating, Although it may be formed by vapor deposition, ion vapor deposition, a molten metal dipping method or a molten metal spraying method, a plating method is preferably employed in terms of cost.

Among the metal plates to be laminated, the stainless steel plate and the first aluminum plate are previously formed as a clad material by a roll rolling method or the like,
A copper plating layer is provided in advance on the joint surface between the first aluminum plate of the clad material and at least the copper plate of the second aluminum plate,
The copper plate may be laminated between the first aluminum of the grad material and the second aluminum, and may be integrated by hot pressing in the laminated state.

Alternatively, the copper plate and the first aluminum plate are preliminarily clad by a method such as roll rolling,
A copper plating layer is provided in advance on the first aluminum plate of the clad material, the joint surface of the stainless steel plate with at least the first aluminum plate, and the joint surface of at least the second aluminum plate with the copper plate,
The stainless plate, the first aluminum plate, the copper plate, and the second aluminum plate may be integrated in a hot press in a state where they are sequentially laminated.

Furthermore, the copper plate and the second aluminum plate are pre-clad by a method such as roll rolling,
A copper plating layer is provided in advance on the joining surface of the stainless steel plate with at least the first aluminum plate, both surfaces of the first aluminum plate,
The first aluminum plate may be sandwiched between the stainless steel plate and the copper plate between the clad materials, and may be integrated by hot pressing in the laminated state.

Furthermore, in the state where the copper plate is sandwiched between the first aluminum plate and the second aluminum plate, a clad material in advance by a method such as roll rolling,
A copper plating layer is provided in advance on the bonding surface between the first aluminum plate of the clad material and at least the first aluminum plate of the stainless steel plate,
The stainless plate and the first aluminum plate may be integrated by hot pressing.

In addition, a precoated aluminum plate provided with a fluororesin layer in advance on one surface of the second aluminum plate, the second aluminum plate may be laminated with the stainless steel plate, the first aluminum plate, and the copper plate and hot pressed. preferable.
In addition, although the said fluororesin layer may be provided in the surface of a 2nd aluminum plate after hot pressing, it is better to use a precoat aluminum plate from a viewpoint which does not give a useless heat history to a joint surface.

In order to further increase the bonding strength between the both surfaces of the copper plate and the first and second aluminum plates, after performing a surface treatment for removing the oxide film, hot pressing is performed as the laminated state.
As the surface treatment, it is preferable to sequentially perform a degreasing treatment with an alkaline solution → a washing treatment with an acidic solution → a rust prevention treatment in which a rust inhibitor is applied. Further, buffing or etching may be performed, or a nickel plating layer → a copper plating layer may be provided.

The composite material of the present invention is suitably used as a blank material for press working, and as a molding material for containers such as an inner pot of an electromagnetic induction heating rice cooker having a bottom wall and a peripheral wall, and an electromagnetic cooking pan.
At that time, a second aluminum plate provided with a fluororesin layer is disposed on the inner surface of the container, and a stainless steel plate serving as a heat generating layer is disposed on the outer surface side of the container by an eddy current flowing by a high frequency magnetic field.

  As described above, the composite material of the present invention has a low hardness aluminum plate or the like interposed as a cushion metal plate between a magnetic metal plate such as stainless steel and a copper plate, which are difficult to be joined, so that a press such as a hot press is used. At the time of processing, conventionally, the bonding strength is weak and the boundary where the delamination of the metal plates to be laminated is most likely to occur can be integrated with a strong bonding strength.

  In addition, a stainless steel plate, a first aluminum plate serving as a cushion metal plate, a copper plate, and a second aluminum plate are laminated, and both surfaces of the copper plate are sandwiched between the first and second aluminum plates, and the stainless steel plate, the first aluminum plate, The composite material in which the copper plating layer is provided on at least the bonding surface of the second aluminum plate and bonded to the stainless steel plate and the copper plate has sufficient bonding strength.

  In addition, when a copper plating layer is interposed, the copper plating layer joins the metal plate by metal diffusion during hot pressing, so that it is possible to increase the bonding strength as compared with bonding by roll rolling, and a plurality of metals. Variations in the thickness of the composite material in which the plates are laminated can be suppressed. As a result, when the composite material of the present invention is drawn and pressed into a container such as an inner pot of a rice cooker or a cooking frying pan, generation of cracks, wrinkles, and delamination can be prevented.

  Moreover, when the composite material of the present invention is used for an electromagnetic cooker, a first aluminum plate and a copper plate are further interposed between the heated stainless steel plate and the second aluminum plate located on the inner surface of the container. Therefore, the thermal conductivity from the stainless steel plate to the second aluminum plate on the inner surface of the container can be increased, the temperature distribution can be made uniform, the side wall of the container can be heated quickly, and the bottom wall and the side wall And the entire cooked food inside the container can be quickly heated.

Embodiments of the present invention will be described with reference to the drawings.
1 and 2 show an embodiment.
The composite material 1 of this embodiment becomes a raw material of the inner pot of an electromagnetic induction heating rice cooker.
The composite material 1 is formed by laminating four metal plates, a stainless steel plate 2, a first aluminum plate 3, a copper plate 4, and a second aluminum 5 serving as cushion metal plates, with a copper plating layer interposed therebetween, and hot-axial addition. It is formed by joining with a hot press of pressure. In the present embodiment, pure aluminum plates are used for the first and second aluminum plates 3 and 5.

As shown in FIG. 1, the stainless steel plate 2 is provided with a nickel plating layer 11 and a copper plating layer 12 in advance on one side of the joining side with the first aluminum plate 3. The stainless steel plate 2 has a thickness of 0.05 to 10.0 mm, the nickel plating layer 11 has a thickness of less than 1 μm, and the copper plating layer 12 has a thickness of 2 to 20 μm.
The first aluminum plate 3 is provided with zinc substitution plating layers 13A and 13B, nickel plating layers 14A and 14B, and copper plating layers 15A and 15B on both surfaces thereof.
The thickness of the first aluminum plate 3 is 0.10 to 10 mm, the thicknesses of the nickel plating layers 14A and 14B are both less than 1 μm, the thicknesses of the copper plating layers 15A and 15B are both in the range of 2 to 20 μm, and zinc replacement The thickness of the plating layers 13A and 13B was less than 0.1 μm.

  As shown on the left side in FIG. 2, the stainless steel plate 2 and the first aluminum plate 3 are overlapped with the copper plating layers 12 and 15 </ b> A being in contact with each other, and a clad material 50 is rolled in advance.

The copper plate 4 has a thickness of 0.03 to 10 mm, and both surfaces thereof are surface-treated in advance to remove the oxide film.
In the surface treatment, for example, a degreasing treatment is performed with an antaritic liquid, followed by washing with an acidic liquid (pickling), and finally applying a rust preventive (rust prevention treatment).
The surface treatment of the copper plate 4 may be a method such as (b) puff polishing, (c) copper plating treatment, or (d) acidic degreasing in addition to the method (a).

The second aluminum plate 5 is provided with a zinc replacement plating layer 16, a nickel plating layer 17, and a copper plating layer 18 on one surface on the joint side with the copper plate 4. On the other hand, a fluororesin layer 20 is provided on the opposite surface.
The thickness of the second aluminum plate 5 is 0.10 to 10 mm, the thickness of the nickel plating layer 17 is less than 1 μm, the thickness of the copper plating layer 18 is 2 to 20 μm, and the thickness of the zinc-substituted plating layer 16 Was less than 0.1 μm.

The fluororesin layer 19 provided in advance on the upper surface side of the second aluminum plate 5 is formed on the surface of the second aluminum plate 5 with fine irregularities 1a formed in advance on the upper surface side by etching, and is colored on the irregular surface. A fluororesin is coated as a base coat 19a with a thickness of 3 to 50 μm. By providing the fine unevenness 1a on the surface of the second aluminum plate 5 at the time of coating, the fluororesin enters the unevenness of the surface, and the base coat 19a with the non-adhesive fluororesin can be performed firmly.
A colorless fluororesin is coated on the surface of the base coat 19a as a top coat 19b with a thickness of 2 to 100 μm. In addition, as a fluororesin used for the base coat 19a and the top coat 19b, it is preferable to use polytetrafluoroethylene (PTFE), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), etc. excellent in heat resistance.
In addition, the number of layers of the fluororesin layer, the color / colorless distinction, and the like can be freely changed and are not limited to the above embodiment.

  As shown on the left side in FIG. 2, the second aluminum plate 5 provided in advance with the stainless steel plate 2 and the first aluminum plate 3, the copper plate 4, and the fluororesin layer 19 that have been previously clad 50 by roll rolling, The blanks B-1, B-2, and B-3 for drawing press work are punched into discs having the same diameter (360 to 450 mm), respectively.

  Two blank materials B-1, B-2, and B-3 shown on the left side in FIG. 2 are sequentially laminated from below to constitute a laminate 20 shown on the right side in FIG.

The laminated body 20 is inserted into a mold consisting of a die and a punch of a hot press apparatus (not shown) equipped with a heating furnace and a hydraulic press with the stainless steel plate 2 as the lower surface.
By simultaneously applying heat and pressure in this state, the copper plating layer between the copper plate 4 and the first and second aluminum plates 3, 5 and the stainless steel plate 2, the first aluminum plate 3, the copper plate 4, and the second aluminum plate 5 are firmly joined to each other.
Hot pressing by the above hot uniaxial pressing method is performed under conditions of a temperature of 200 to 300 ° C., a pressure of 200 to 1000 kg / cm ² , and a pressing time of 10 minutes to 30 hours, thereby reducing the presence of gas molecules at the bonding interface. In order to promote the diffusion of the metals to be joined, it is preferably performed under reduced pressure or under vacuum.

As shown in FIG. 3, the four metal plates of the stainless steel plate 2, the first aluminum plate 3, the copper plate 4, and the second aluminum plate interpose a copper plating layer (not shown in FIG. 3) between the hot presses. Thus, a disc-shaped blank material joined firmly is manufactured.
This blank material is pressed by drawing press as an inner pot of a rice cooker including a container having a bottom wall and a side wall and a flange at the upper end of the side wall.

"Experimental example"
Experimental examples 1 to 5 of the present invention in which four metal plates were laminated A plurality of composite materials of Comparative Examples 1 to 3 in Patent Document 1 in which three metal plates were laminated were prepared.
The thickness, material, etc. of the metal plates of Experimental Examples 1 to 5 and Comparative Examples 1 to 3 are shown in Table 1 below.

The fluororesin layer was coated with two layers of tetrafluoroethylene resin dispersion and baked into a fluororesin layer having a thickness of 40 μm.
On both surfaces of the first aluminum plate and the opposite surface of the fluororesin layer of the second aluminum plate, a zinc replacement plating layer (thickness less than 0.1 μm), a nickel plating layer (thickness 0.5 μm), a copper plating layer ( A thickness of 10 μm) was applied.
In the table, the diameter indicates the diameter when punched into a blank as a blank.

  The surface treatment of the copper plates of Examples 1 to 5 and Comparative Examples 1 to 3 was the normal treatment (i), that is, degreasing → pickling → rust prevention treatment.

In Example 1 and Example 3, a stainless steel and a first aluminum plate were clad rolled in advance, and a copper plate was sandwiched between the aluminum plate and the second aluminum plate of the clad material and hot pressed. The hot pressing was performed under the optimum conditions of temperature 200 to 300 ° C., pressure 200 to 1000 kgf / cm ² , and time 10 minutes to 30 hours.
In Example 2 and Example 4, a stainless plate, a first aluminum plate, a copper plate, and a second aluminum plate were laminated in this order and hot pressed. The conditions for hot pressing were the same as in Examples 1 and 3.

  In Comparative Examples 1 to 3, the first aluminum plate serving as a cushion material was not provided, and a stainless steel plate, a copper plate, and a second aluminum plate were laminated and hot pressed. The hot press conditions were the same as in the examples.

  The thicknesses of the composite materials of Examples 1 to 5 after hot pressing were 3.0 to 3.7 mm. On the other hand, the total thickness of the composite materials of Comparative Examples 1 to 3 was 2.5 to 3.1 mm.

Regarding the bonding strength, as shown in Table 2, the appearance measurement and the prepared composite material were cut into strips with a width of 5 mm, and the metal plates on both sides of the bonding interface to be measured for bonding were in opposite directions (180 ° direction). A tensile load was applied to the test piece, and the bonding strength was measured while peeling.
In appearance measurement, Examples 1 to 3 seemed to be joined at first glance. On the other hand, the composite materials of Comparative Examples 1 to 3 were not joined in appearance.
In Table 2, “2/2” indicates that two composite materials were prepared and both were joined, and “30/30” is the same. “1/2” indicates that one of the two sheets is joined at first glance, but the other one is not joined visually.

In Table 2 showing the results of the measurement of the bonding strength,
“Unchecked” in the table indicates that since the bonding strength was larger than the chucking force of the tensile load tester, the material was removed from the chuck before measuring the bonding strength, and could not be measured.
In the table, “Unable to squeeze out” means that the metal plate on both sides of the joint interface could not be peeled off and could not be applied to the tensile load tester because it was too tight. Indicates.
“Out of material” in the table indicates that since the bonding strength was greater than the material strength, the material was broken before the bonding strength was measured, and could not be measured.

From the measurement of the bonding strength in Table 2, in Examples 4 and 5, the bonding strength between the stainless steel and the first aluminum plate was 17 kgf / 5 mm or more. The bonding strength between the first aluminum plate and the copper plate of Examples 1 to 5 was 12 kgf / 5 mm or more. The bonding strength between the copper plate and the second aluminum plate in Examples 1, 3, 4, and 5 was also 10 kgf / 5 mm or more.
In contrast, Comparative Examples 1 to 3 could not be measured because there was no first aluminum plate, but the joining strength between the stainless steel plate and the copper plate was very low, 0 to 2.4 kgf / 5 mm.

  From this test result, when three metal plates of stainless steel plate-copper plate-aluminum plate were hot-pressed through a copper plating layer, in particular, sufficient bonding strength was not obtained between the stainless steel-copper plates. -When the four metal plates of the first aluminum plate, the copper plate, and the second aluminum plate are hot pressed through the copper plating layer, it is sufficient between the stainless steel plate and the first aluminum plate and between the first aluminum plate and the copper plate. It was confirmed that a good bonding strength was obtained.

Thus, by increasing the bonding strength, it is possible to prevent cracks, wrinkles, and delamination when the composite material of the present invention is drawn and processed as a container for an electromagnetic cooker.
Furthermore, since the aluminum plate serving as the heat transfer layer is also interposed between the stainless steel plate and the copper plate, heat transfer to the copper plate can be performed more quickly and the temperature distribution of the copper plate can be made uniform. As a result, the temperature of the second aluminum plate on the inner surface of the container that is transferred from the copper plate is quickly raised, and the temperature distribution between the bottom wall and the side wall can be made uniform.

Using the composite materials of Examples 1 to 5 and Comparative Examples 1 to 3, by a press press, the bottom wall and the side wall are provided, and the press is used as an inner pot of a rice cooker including a container having a flange at the upper end of the side wall. processed.
As a result, as shown in Table 2, the composite materials of Examples 1 to 5 were moldable, but in Comparative Example 1, delamination occurred at the flange portion. In Comparative Example 2, more than half was not moldable.

  The composite material of the present invention is suitably used as an inner pot of an electromagnetic heating rice cooker, a pan for a battery cooker, or the like.

It is drawing which shows the metal plate which comprises the composite material of embodiment which concerns on this invention. It is sectional drawing which shows the state by which the said composite material was joined integrally. It is a schematic perspective view which shows the state by which the metal plate was cut | disconnected circularly and was laminated | stacked.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Composite material 2 Stainless steel plate 3 First aluminum plate 4 Copper plate 5 Second aluminum plate 12, 15A, 15B, 18 Copper plating layer 11, 14A, 14B, 17 Nickel plating layer 20 Laminate 50 Cladding material

Claims (12)

A copper plate is interposed between the magnetic metal plate and the non-magnetic metal plate,
A composite material, wherein a cushion metal plate made of a metal having a lower hardness than the magnetic metal plate and the copper plate is interposed between the magnetic metal plate and the copper plate.   The composite material according to claim 1, wherein the cushion metal plate is made of an alloy aluminum plate or a pure aluminum plate. The magnetic metal plate is a stainless steel plate, the cushion metal plate is a first aluminum plate made of an alloy aluminum plate or a pure aluminum plate, and the nonmagnetic metal plate is a second aluminum plate made of an alloy aluminum plate or a pure aluminum plate,
The composite material according to claim 1 or 2, wherein the stainless steel plate, the first aluminum plate, the copper plate, and the second aluminum are laminated, and a copper plating layer is interposed between the metal plates.   The composite material according to claim 2 or 3, wherein the copper plating layer is provided on a surface of the stainless steel plate and / or the first and / or second aluminum plate via a nickel plating layer.   The composite material according to claim 2 or 3, wherein the copper plating layer is provided on the surfaces of the first and second aluminum plates via a zinc plating layer and a nickel plating layer.   The composite material for electromagnetic cooking which consists of a composite material of any one of Claims 1 thru | or 5.   The composite material for an electromagnetic cooker according to claim 6, wherein a fluororesin layer is provided on a surface of the second aluminum plate opposite to a joint surface with the copper plate.   In order from one side to the other side, the stainless steel plate, nickel plating layer, copper plating layer, nickel plating layer, first aluminum plate, nickel plating layer, copper plating layer, copper plate, copper plating layer, nickel plating layer, second The composite material for an electromagnetic cooker according to claim 6 or 7, wherein an aluminum plate and a fluororesin layer are laminated. It is a manufacturing method of the composite material according to claim 1,
Using stainless steel as the magnetic metal plate, using a first aluminum plate as the cushion metal plate, using a second aluminum plate as the non-magnetic metal plate,
A stainless steel plate, a first aluminum plate, a copper plate, and a second aluminum plate are laminated in order and integrated by hot pressing, and the composite material is produced.   The said copper plating layer is previously provided in the joining surface with the at least 1st aluminum plate of the said stainless steel plate, both surfaces of the said 1st aluminum plate, and the at least joining surface with the copper plate of the said 2nd aluminum plate. A method of manufacturing a composite material. The stainless steel plate and the first aluminum plate are preliminarily clad by a method such as roll rolling,
A copper plating layer is provided in advance on the joint surface between the first aluminum plate of the clad material and at least the copper plate of the second aluminum plate,
The method for producing a composite material according to claim 9, wherein the copper plate is laminated between the first aluminum of the grad material and the second aluminum, and is integrated by hot pressing in the laminated state.   12. The method for manufacturing a composite material according to claim 9, wherein both surfaces of the copper plate are hot pressed as the laminated state after performing a surface treatment for removing an oxide film.

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