JP2006341272A - Composite material, and method for producing composite material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simply form gap parts in a composite material being the raw material for an electromagnetic induction heating type vessel. <P>SOLUTION: Each metal layer for joining is beforehand provided on the whole face of the confronted face in a nonmagnetic metal sheet and a magnetic metal sheet, and they are set between a pair of press dies arranged so as to be confronted on both the sides in the axial direction of a hot press apparatus. At least either in the press dies is provided with step-like projecting parts of projecting toward the confronted mating press die. Upon a hot press, the respective metal sheets in the regions sandwiched between the step-like projection parts and the mating press die are formed as joints at which the metal layers for joining are integrally joined. On the other hand, the respective metal sheets in the regions not sandwiched by the projecting step parts are formed as non-joined parts to form into gap parts, thereby obtaining the composite material having the gap parts partially. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a composite material in which metal plates are laminated and a method for producing the same, and in particular, it is suitably used as an electromagnetic induction heating material, and has improved heat insulation performance by interposing a gap between the metal plates to be laminated. It is.

Conventionally, an electromagnetic induction heating container or the like used for an inner pot or the like of an IH jar rice cooker is formed of a composite material of a magnetic metal plate and a nonmagnetic metal plate. 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. The coil is opposed to the electromagnetic induction heating.
In many cases, the clad material is formed by laminating the non-magnetic metal plate and the magnetic metal plate by roll rolling.

Moreover, in the composite material used for this kind of electromagnetic induction heating container, it is requested | required to provide a space | gap part between the said metal plates, and to have the heat insulation performance which can hold | maintain a heating state.
In response to the above request, the applicant of Japanese Patent Application Laid-Open No. 2004-9097 (Patent Document 1), as shown in FIG. 9, a plating layer 2 that becomes a bonding metal in advance on the bonding surface of the nonmagnetic metal plate 1. The plating layer 2 is masked to form the non-plated portion 3 while the plating layer 5 serving as a bonding metal is provided in advance on the entire bonding surface of the magnetic metal plate 4. When the plates 1 and 4 are joined by a hot press method (hot-axial pressure), the non-plated portion 3 is left as an unjoined vacuum portion, and a manufacturing method of the composite material provided with the vacuum portion 6 is provided. providing.

  According to the manufacturing method, only one of the joining surfaces of the metal plates to be joined to each other, only a non-plated portion is provided, and when these metal plates are hot-pressed, the metal plates are not in a non-plated portion. It cannot be integrally joined, and the vacuum part 6 can be provided reliably.

JP 2004-9097 A

According to the above-described method, the vacuum part can be reliably formed only by not providing the non-plated part on the joining surface of one metal plate, but the plating layer 2 and the non-plating are formed on the joining surface of one metal plate. The operation of providing the part 3 is very time-consuming and has a problem of increasing the processing cost.
That is, first, as shown in FIG. 10 (A), a masking sheet M made of a polyethylene sheet or the like and not yet provided with an exposed portion is pasted on the surface of the metal plate 1. When the thickness is a very thin plating layer having a thickness of about 1 to 50 μm, the masking sheet itself is a thin sheet having a thickness of about 1 to 50 μm. Thus, it is very difficult to apply a very thin masking sheet to the surface of the metal plate without causing wrinkles or the like. In addition, if there are wrinkles, it becomes difficult to obtain a masking effect because molten metal permeates into the wrinkles during plating.
After pasting the masking sheet M on the surface of the metal plate 1, as shown in FIG. 10 (B), the cut lines Z1 and Z2 are made in the masking sheet M with a laser, and then, as shown in FIG. 10 (C). Then, the removed portions A-1 and A-2 are peeled along the cut lines Z1 and Z2 to expose a region to be plated. At that time, the peeling operation of the removed portions A-1 and A-2 is very difficult because the masking sheet M is attached to the metal plate and is very thin.
When the peeling operation cannot be performed accurately, the position of the vacuum part to be formed is shifted from the design position, and it is necessary to peel off the masking sheet from the surface of the metal plate and start again.

Furthermore, as shown in FIG. 10D, when the masking sheet M is plated with the metal plate 4 attached, the thin masking sheet M is heated by the molten metal 2 ′ to be plated, and the metal plate 1 is heated. It tends to be in a welded state.
After plating, it is necessary to peel off the masking sheet M from the metal plate 1 as shown in FIG. 10E. However, the masking sheet M is very difficult to peel off, and the masking sheet M is peeled off using a peeling tool. However, it takes a lot of work. Furthermore, the surface of the metal plate 4 may be damaged when the masking sheet M is peeled off.

  As described above, it is necessary to apply a masking sheet on the surface of the metal plate, make a cut with a laser, peel off the removed portion along the cut, and then perform plating, and then peel off the masking sheet M after plating. Therefore, there is a problem that, in practice, it takes a lot of work, and a high degree of skill is required, so that a defect rate is considerably increased. As a result, the process of partially providing the non-plated portion on the joint surface of the metal plate is a major factor in increasing the cost.

Also, a masking sheet is formed according to the application size of the composite material, and the composite material is provided with a plated portion and a non-plated portion at a position defined by the masking sheet. For example, the composite material is cooked for electromagnetic cooking. When the inner hook is used, it is limited to an inner hook of a predetermined size.
Therefore, there is a problem that it cannot be used as a composite material for forming inner pots of other sizes.

  The present invention has been made in view of the above-described problems, and enables the formation of a gap between metal plates to be joined without providing a plated portion and a non-plated portion on the joining surface of the metal plate, and the masking sheet. It is an object of the present invention to improve productivity by eliminating the work process using the material, and as a result, to reduce costs and to generalize the materials used.

In order to solve the above problems, as a first invention,
A method for producing a composite material in which a plurality of metal plates to be laminated are joined by a hot uniaxial pressing method (hot press),
The plurality of metal plates to be laminated are a nonmagnetic metal plate and a magnetic metal plate, or a nonmagnetic metal plate and a magnetic metal plate, and one or a plurality of intermediate metals interposed between the nonmagnetic metal plate and the magnetic metal plate. A board,
A metal layer for bonding is previously provided on the entire surface of at least one facing surface of the plurality of metal plates to be laminated,
The plurality of metal plates to be laminated are set between a pair of press dies arranged opposite to each other on both sides in the axial direction of the hot press device, and facing at least one of the press dies toward the opposite press die. Providing a protruding stepped portion,
At the time of hot pressing, the metal plates in the region sandwiched between the stepped protrusion and the counterpart press die are formed as a joint where the joining metal layer is integrally joined, while the region not sandwiched by the projecting step The metal plate is formed as an unjoined portion that becomes a void portion, and a composite material partially having a void portion is provided.

As described above, in the present invention, a hot press apparatus provided with a press die provided with a joining metal layer on each of the entire joining surfaces of the metal plates to be joined and provided with stepped protrusions is used. , Hot pressing under high temperature and pressure and vacuum (or reduced pressure).
Since the press die of the hot press device is provided with stepped protrusions, the space between the pair of opposed press dies is narrowed in the region where the stepped protrusions are provided, while the portion where the stepped protrusions are not provided is pressed. The space between the molds will be relatively widened. As a result, there is a difference in the pressing force applied to the metal plate between the press dies, and metal diffusion occurs between the joining metals in contact with each other in the region where the stepped protrusions are provided and the interval is narrowed. Join together. On the other hand, in the region where the stepped protrusion is not provided, no pressing force is applied, and even when the bonding metal layer is provided on the entire surface of the opposing bonding surface and these bonding metal layers are in contact, the opposing bonding metal Metal diffusion does not occur in between, resulting in an unjoined void.
In addition, since the gap portion is hot-pressed in a vacuum state or a reduced pressure state, the gap portion is substantially in a vacuum state. When the gap is substantially vacuum, the heat insulation effect can be enhanced, and as a result, the heat retention performance can be increased when the container is used.

As described above, since the joining metal layer can be provided on the entire joining surface, it is not necessary to provide a plating layer and a non-plating portion using a masking sheet as in Patent Document 1.
As the hot press method employed in the present invention, the methods disclosed in JP-A Nos. 6-179083 and 9-129363 can be suitably used.

The stepped protrusion provided in the press die may be either one of the upper and lower press dies, or may be formed to face both. Further, the stepped protrusions are provided along at least the entire outer periphery of the press die, and the entire outer periphery of the composite material is provided in a state where the metal plates are joined together and the gap is sealed. By providing a step-shaped protrusion having a required shape at a required position within the region surrounded by the step-shaped protrusion, a composite material having a required-shaped gap at the required position can be easily manufactured by hot pressing. it can. That is, a stepped protrusion may be provided on the press die at a portion other than the gap.
In addition, it is good also considering a press die as a thick plate, providing a recessed part partially, and making a step-shaped protrusion part other than this recessed part.
The material of the press die provided with the stepped protrusions is a material that can withstand high temperature and pressure because it transmits high pressure to the metal plate at high temperature, and is preferably formed of iron-based heat-resistant alloy, ceramic, carbon or the like.
As described above, in the present invention, the bonding metal layer can be provided over the entire joining surface of the metal plate as the composite material, and the shape and position of the press-shaped stepped protrusion are changed. As a result, it is possible to obtain a composite material having a void portion having an arbitrary shape at an arbitrary position, and the metal plate itself provided with the bonding adhesive layer can be a general-purpose product.

In the plurality of metal plates to be laminated, between the magnetic metal plate and the intermediate metal plate, between the intermediate metal plate and the non-magnetic metal plate, and between the intermediate metal plates in the case of laminating the plurality of intermediate metal plates, between the opposing layers, If the bonding metal layer is provided on the bonding surface, unbonded portions that form a plurality of gaps between different layers can be formed in the region not sandwiched between the stepped protruding step portions of the press die.
As described above, when a plurality of gaps are provided between the multi-layered metal plates, a more heat insulating effect can be achieved, and when the container is used, the heat retaining performance can be further improved.

The bonding metal layer is required in advance by plating, vapor deposition, ion vapor deposition, molten metal dipping method or molten metal spraying method on the entire surface of the non-magnetic metal plate, magnetic metal plate or intermediate metal plate facing the bonding side. The thickness is provided.
The bonding metal layer may be provided by any method, but it is preferable to provide the bonding metal layer by plating from the viewpoint of cost and uniform thickness.
Further, the bonding metal layer respected on the bonding surface side of each metal plate is not limited to a single plating layer, and may be a multilayer plating layer. Even when the thickness of the bonding metal layer is multilayer plating, the thickness of the bonding metal layer is 2 μm or more and 20 μm or less, preferably about 8 to 18 μm. Therefore, when the opposing joining metal layers are joined by pressing, the total thickness is preferably about 4 μm to 40 μm.

  When manufacturing a composite material that is a material for an electromagnetic induction heating container, aluminum or an aluminum alloy is preferably used as a nonmagnetic metal plate to be joined by hot pressing, and stainless steel, iron, or the like is used as the other magnetic metal plate. Preferably used.

The one nonmagnetic metal plate and one magnetic metal plate are used as a unit set (one unit set including an intermediate metal plate if necessary), and this unit set is set between a plurality of the press dies. Thus, a plurality of composite materials having voids can be manufactured simultaneously and productivity can be improved.
As described above, in order to simultaneously form a plurality of composite materials by a single hot press, when laminating a large number of metal plates in a press mold, the stepped protrusions are projected to face both of the opposed press molds. May be.
When the thickness of the nonmagnetic metal plate and the magnetic metal plate is relatively thin, even if a stepped protrusion is provided only on one of the press dies, Can be provided.

  When a plurality of composite materials are laminated and hot-pressed as described above, it is preferable that a separator as thin and durable as possible with a thickness of 2 mm or less is interposed between each pair of metal plates. As the separating material, ceramic sheets such as Al foil alumina, carbon sheet sheets, knitted fabrics such as glass cloth, and cloth shapes can be employed. Further, it may be a separator made of Mo (molybdenum), W (tungsten), stainless steel, anodized, aluminum, carbon, or ceramic (alumina, zirconia, silicon nitride).

When the composite material of the non-magnetic metal plate and the magnetic metal plate is formed by a hot uniaxial pressing method (hot press), the temperature is 180 to 600 ° C., preferably 200 to 450 ° C., and the pressure is 200 to 1000 kg / It is preferable to set it to cm < ² >, pressurization time 10min-30h, Preferably it is 30min-1h, under reduced pressure, or the vacuum below 10 < ^-1 > torr.
By performing hot pressing under the above-described conditions, in the portion where the stepped protrusions are not provided, the opposing joining surfaces of the metal plate can be made into gaps as unjoined portions. On the other hand, in the region where the stepped protrusions are provided, by reducing the presence of gas molecules at the bonding interface, metal diffusion between the bonding metals can be promoted, and the bonding strength can be increased. In the composite material of the present invention, the bonding strength between the metal plates is preferably 3 kg or more in terms of the separation strength of the composite plate having a width of 5 mm.
When metal plates are joined together by hot pressing to form a composite material, the plate thickness, bonding strength, and the like can be made uniform, and the occurrence of cracks, wrinkles, and the like can be prevented when drawing.

As a second invention, there is provided a method for producing a container having a bottom wall and a peripheral wall by drawing and pressing the composite material produced by the above method.
In this method, the metal plates facing each other with the unjoined portion serving as the integral joined portion and the gap portion having different tensile rates, and due to the difference in elongation generated during the drawing press processing, The gap portion to be formed is enlarged, and the enlargement ratio of the gap portion is preset by the tensile rate of the opposing metal plate.

In the composite material manufactured by the hot press, metal diffusion occurs between the opposing bonding metal layers, and a portion where the bonding metal layers are integrally bonded and a portion where the bonding metal layer is not bonded and become a void are formed. . The volume of the portion that becomes the gap is relatively small, and in some cases, the physical properties are unjoined, but the gap portion is so small that it can be seen in the contact state by visual observation.
This composite material with a small gap is made into a container having a bottom wall and a peripheral wall by drawing press processing. As a result, the gap is enlarged due to the difference in tensile rate during the drawing press processing.
That is, the metal plate side having a high tensile rate swells with respect to the metal plate side having a low tensile rate, and the volume of the gap is increased.
For example, in an aluminum plate and a stainless steel plate, since aluminum has a higher elongation rate at the time of tension, the aluminum plate swells with respect to the stainless steel plate, and the gap portion is enlarged.
In this way, the gap can be expanded by applying a tensile force to the composite material formed by hot pressing. And it becomes possible to calculate the volume of the gap part to be expanded from the difference in the tensile rate between the metal plates. .

Furthermore, the metal plates facing each other across the integral joint and the unjoined portion that becomes the gap are different from each other in the coefficient of thermal expansion, and are heated at the required temperature during the drawing press processing or after the drawing press processing,
The gap formed in the unjoined part may be enlarged due to the difference in the thermal expansion coefficient, and the enlargement ratio due to the thermal expansion of the gap may be set in advance by the thermal expansion coefficient of the opposing metal plate.
As in the case of using the difference in the tensile rate, the metal plate having a large thermal expansion coefficient swells with respect to the metal plate having a small thermal expansion coefficient, and the volume of the void portion increases. For example, in an aluminum plate and a stainless steel plate, since aluminum has a higher expansion coefficient during heating, the aluminum plate swells with respect to the stainless steel plate, and the gap is enlarged.

  As described above, when the composite material is drawn and pressed, the gap is enlarged, and when heated, the gap can be further enlarged. As a result, the heat insulation space is increased and the container is kept warm. Can increase the sex. And the volume which a space | gap part increases can be calculated | required from the difference of the tensile rate and thermal expansion coefficient of the metal plate of the both sides which pinch | interpose a space | gap part. In other words, a metal plate having a required tensile rate and thermal expansion coefficient may be combined in accordance with the volume to be increased.

The present invention provides, as a third invention, a composite material in which a nonmagnetic metal plate and a magnetic metal plate are joined together with a gap interposed therebetween,
The non-magnetic metal plate and the magnetic metal plate are provided with a bonding metal layer on each of the bonding surface sides facing each other,
In the gap, the bonding metal layers are unbonded and face each other with a space therebetween, while the bonding metal layers are bonded in a portion surrounding the gap. Is provided.

In the composite material, since an unjoined gap is provided between the nonmagnetic metal layer and the magnetic metal layer, heat insulation performance can be obtained by the presence of the gap.
In addition, composite materials having various performances can be obtained by simply changing the position and shape of the gap and the combination of the thickness and material of the metal plate forming the nonmagnetic metal layer and the magnetic metal layer.
Therefore, the composite material of the present invention is excellent in heat insulation performance, can be easily changed in design according to required performance, is excellent in versatility, and can be used for various applications.

  One or a plurality of intermediate metal plates are interposed between the nonmagnetic metal plate and the magnetic metal plate, the opposing surface of the nonmagnetic metal plate and the intermediate metal plate, the opposing surface between the intermediate metal layer plates, the intermediate metal plate and the magnetic metal plate Bonding may be performed by partially interposing a gap at any one or a plurality of locations on the opposing surface.

  A composite material in which a gap portion is provided between the nonmagnetic metal plate and the magnetic metal plate, and one or a plurality of gap portions are provided between any of the nonmagnetic metal plate, the intermediate metal plate, and the magnetic metal plate. Any of the composite materials can be easily manufactured by the manufacturing method of the composite material of the first invention, but is not limited to the manufacturing method of the first invention.

The composite material having voids according to the present invention is bonded to the entire surface of the non-magnetic metal plate and the magnetic metal plate (and the intermediate metal plate interposed if necessary) on the bonding surface side of the metal plate having a uniform thickness. A metal layer having a uniform thickness is joined and formed. Therefore, in the portion where the gap portion is interposed, the cross-sectional plate thickness of the composite material is larger by the thickness of the vacuum layer than the cross-sectional plate thickness of the portion joined without the gap portion being interposed. However, the thickness of the gap portion may be less than about 1 mm when the gap portion is not desired to be visually recognized, and conversely, 1 mm or more when the presence of the gap portion is desired to be visible. Thus, a step can be generated.
Furthermore, when it is desired to increase the volume of the gap, a shallow recess may be provided in advance in the nonpolar metal plate and / or the magnetic metal plate facing the gap. Since the bonding metal layer is provided over the entire side surface, the bonding metal layer is also provided on the inner surface of the recess. Thus, the heat insulation performance can be further improved by increasing the volume of the gap.

When the composite material of the present invention is used as a material for an electromagnetic induction heating type rice cooker inner pot or an electromagnetic induction heating type pan, it is a circular blank, and the center part is made into a bottom wall by drawing press processing, and the outer periphery. It is preferable that the portion is formed on the peripheral wall, and the gap is provided on the outer peripheral portion serving as the peripheral wall.
That is, each of the magnetic metal plate and the nonmagnetic metal plate each provided with a bonding metal layer on the opposite bonding surface side is formed into a circular punched shape, and in this state, between the pair of press dies of the hot press apparatus. And a gap is provided in the outer periphery.
If the tensile rates of the metal plates on both sides sandwiching the gap are different during the drawing press processing, the gap is enlarged as described above. Further, when the scale is printed on the pan in the rice cooker and heated for the purpose of fixing the printing, the thermal expansion coefficients of the metal plates on both sides sandwiching the gap by the heating are different as described above. Further, the gap can be increased.

As described above, the space between the magnetic metal plate that generates heat by electromagnetic induction and the nonmagnetic metal plate that becomes the heat transfer layer is provided at the position that becomes the peripheral wall, thereby maintaining the heat insulation of the electromagnetic induction heating container. Heat insulation performance can be improved, and the electricity cost required for heat insulation can be greatly reduced.
Further, the composite material of the present invention can be formed by drawing to form a container having a desired shape having a bottom portion and a peripheral wall, and the void portion can be enlarged by a pulling force during pressing.

The composite material formed into a circular blank has a concentric annular space provided in the outer peripheral portion thereof, and when formed into a rice cooker inner pot or the like by a drawing press process, a continuous void is formed around the entire circumference of the peripheral wall. Thus, by providing a space | gap part continuously in the perimeter of a surrounding wall, heat insulation performance can be improved uniformly in the circumferential direction, and the heat retention without a nonuniformity can be aimed at entirely.
The gaps can be provided so as to be scattered in the vertical direction, the cross direction, or scattered in parallel with the peripheral wall, and can be appropriately set to a desired position and configuration according to the required performance.

The nonmagnetic metal layer is formed of a metal plate made of aluminum, aluminum alloy, nonmagnetic stainless steel, or the like,
The magnetic metal layer is preferably formed of a metal plate made of magnetic stainless steel such as ferritic stainless steel, iron, iron alloy, nickel, nickel alloy, copper, copper alloy, cobalt, cobalt alloy or the like.
Moreover, it is preferable that the said joining metal layer provided in the joining surface of the said magnetic metal plate and a nonmagnetic metal plate is formed from metal layers, such as copper, aluminum, nickel, silver, and tin.
In particular, when the bonding metal is made of copper, the bonding force can be increased.

When a cooking container including an electromagnetic induction heating rice cooker is provided, a fine uneven portion is provided on the surface of the nonmagnetic metal positioned on the inner surface of the container, and a fluororesin layer is provided on the surface of the uneven portion. It is preferable.
Thus, by providing a fine uneven surface by etching or the like on the surface of the nonmagnetic metal plate, the fluororesin enters the surface unevenness, and the base coat with the non-adhesive fluororesin can be performed firmly. Therefore, it is possible to easily impart releasability to the composite material.

As described above, in the present invention, in order to form the void portion, the entire surface of the metal plate on the bonding surface side is plated for bonding without using a masking sheet to provide a plating layer and a non-plating portion. A metal layer can be provided, and by simply improving the shape of the press die of the hot press apparatus, it is possible to easily provide a void portion having an arbitrary shape at an arbitrary position during hot pressing.
Therefore, the metal plate provided with the bonding metal layer on the entire surface is not limited to the use for forming the gap at a predetermined position of a predetermined size, and can be used for other purposes and can be provided with versatility.

  Further, in a composite material having a non-magnetic metal plate and a magnetic metal plate on both outer sides, a substantially vacuum void portion having an arbitrary shape can be provided at an arbitrary position inside the composite material. When an induction heating container, for example, an inner pot of an IH jar rice cooker, is used, the heat retention performance can be dramatically improved. Therefore, it can be set as the rice cooker which can save the electricity bill at the time of heat retention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a composite 10 of the present invention. The composite material 10 is a laminate of a nonmagnetic metal plate and a magnetic metal plate, and is used as a material for an electromagnetic induction heating container such as an inner pot of an IH jar rice cooker.

The composite material 10 has a disk shape using an aluminum plate 11 as a nonmagnetic metal plate, and a disk shape using a stainless steel plate 12 as a magnetic metal plate. Although not shown in FIG. 1, the upper surface of the aluminum plate 11 is coated with fluorine.
In the composite material 10, an annular gap 15 having a required width W that is concentric with the center of the disc is provided between the aluminum plate 11 and the stainless plate 12.

  As shown in FIGS. 2A and 2B, the composite material 10 has a copper layer 16 constituting a joining metal layer on the entire surfaces of the joining surfaces 11a and 12a of the aluminum plate 11 and the stainless steel plate 12 that are joined to each other. 17 is provided by plating, and the copper layers 16 and 17 are joined by a hot-axial pressing method (hot press) to provide an integrated joint 28 and the copper layers 16 and 17 are not joined. The unbonded portion 15-1 that becomes the gap 15 is formed.

The nonmagnetic metal plate is not particularly limited as long as it has a good thermal conductivity and becomes a heat transfer layer, and materials such as aluminum, aluminum alloy, and nonmagnetic stainless steel are preferably used. The aluminum plate 11 is used from the viewpoint of good conductivity and workability.
The aluminum plate 11 has a thickness of 0.5 to 5.0 mm (1.7 mm in this embodiment) from the viewpoint of strength, thermal conductivity, etc., and has a substantially developed shape of the electromagnetic induction heating container 6 described later. It is punched into a circular shape. Moreover, the plating thickness of the copper layer 16 provided on the joining surface of the aluminum plate 11 is 1 to 50 μm (10 μm in this embodiment).

The magnetic metal plate is not particularly limited as long as an eddy current flows by a high-frequency magnetic field to form a heat generating layer, such as magnetic stainless steel, iron, iron alloy, nickel, nickel alloy, copper, copper alloy, cobalt, cobalt alloy, etc. In this embodiment, the magnetic stainless steel plate 12 is used as described above.
The stainless steel plate 12 has a thickness of 0.1 to 3.0 mm (0.5 mm in the present embodiment) and is punched into a circle so as to have the same diameter as the aluminum plate 11. The thickness of the copper layer 16 to be provided is 1 to 50 μm (10 μm in this embodiment).

  The composite material 10 of the present invention uses the hot press device 50 shown in FIGS. 3 and 4 to apply heat and pressure in the axial direction at the same time to hot the copper layers 16 and 17 of the aluminum plate 11 and the stainless steel plate 12. The composite material 10 having the gap 15 is manufactured by joining with a press.

First, the hot press apparatus 50 will be described. 60 is a heating furnace body, 61 is a heater, 62 is a mold (mortar) disposed in the heating furnace body, 63 is a hydraulic cylinder, 64 is a vacuum pump, and 65 is a heat insulating material. is there.
The die 63 includes a fixed lower press die 52 and an upper press die 51 that is lowered by a hydraulic device 63. Hot plates 53 and 54 are fixed to the upper and lower surfaces of the upper and lower press dies 51 and 52, respectively.
The mold (mortar) 62 serves as a guide so that the metal plates stacked inside the mold do not collapse when pressed.

An annular stepped protrusion 52a is provided on the upper surface of the lower press die 52 along the outer peripheral edge, and a circular stepped protrusion 52b is protruded at the center, and these stepped protrusions 52a and 52b are provided. By providing, the space between them is an annular recess 52c.
The lower surface 51a of the upper press die 51 facing the upper surface of the press die 52 and the stacked set space C of the metal plates is a flat surface.
Therefore, in the set space C sandwiched between the upper surface of the lower press die 52 and the lower surface of the upper press die 51, the vertical dimension L1 is shortened at the position where the stepped protrusions 52a and 52b are provided. The vertical dimension L2 is lengthened in the recess 52c where no projecting portion is provided.

Next, a method for manufacturing the composite material 10 will be described in detail.
First, as shown in FIG. 5A, the aluminum plate 11 and the stainless steel plate 12 are punched into the same disk shape.
Next, as shown in FIG. 5 (B), copper plating is applied to the entire surface of the disk-shaped aluminum plate 11 as the bonding surface 11a and the entire surface of the stainless steel plate as the bonding surface 12a. A joining metal layer consisting of 16 and 17 is formed.

Further, on the other surface of the aluminum plate 11, fine irregularities are formed in advance on the surface by an etching process, and a fluororesin layer 18 is provided on the upper surface. The fluororesin layer 18 includes a base coat layer 18a provided by coating a colored fluororesin, and a top coat layer 18b by coating a colorless fluororesin on the surface of the base coat 18a.
The thickness of the base coat layer 18a is 5 to 60 μm (25 μm in this embodiment), and the thickness of the top coat layer 18b is 5 to 50 μm (25 μm in this embodiment).
As the fluororesin used for the base coat layer 18a and the top coat 18b, it is preferable to use polytetrafluoroethylene (PTFE), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA) or the like excellent in heat resistance.

  As described above, the copper layer 16 is provided on the entire surface of the aluminum plate 11, the fluororesin stainless steel 18 is provided on the entire other surface, and the copper layer 17 is formed on the entire surface of the stainless plate 12. Is set between press dies 51 and 52 facing each other. At that time, the copper layers 16 and 17 of the aluminum plate 11 and the stainless steel plate 12 are arranged to face each other.

In this state, as shown in FIG. 5D, hot pressing with hot uniaxial pressing is performed. The hot press is performed under conditions of a temperature of 200 to 260 ° C., a pressure of 200 to 1000 kg / cm ² , and a pressurization time of 10 min to 30 h. When copper is used as the bonding metal, copper has a large diffusion coefficient in the low temperature range, so the temperature is relatively low and the pressure is on the low pressure side within the above range. Further, since the fluororesin 18 is provided on the aluminum plate, the fluororesin is likely to deteriorate when the temperature exceeds 260 ° C., so that the temperature is set to 260 ° C. or less as described above.
The atmosphere may be in the air or non-oxidizing gas (Ar, N ₂ , He, CO _2, etc.). In order to reduce the interposition of gas molecules at the bonding interface and promote the diffusion of bonding metals, The pressure is reduced or a vacuum atmosphere of 10 ⁻¹ torr or less.

At the time of hot pressing, in the set space C, as described above, the vertical dimension L1 is shortened at the position where the stepped protrusions 52a and 52b are provided, and the vertical dimension L2 is set at the recess 52c where the stepped protrusion is not provided. To make it longer. Therefore, the pressing force applied to the aluminum plate 11 and the stainless steel 12 in the region where the stepped protrusions 52a and 52b are provided to shorten the vertical interval is increased, and a strong force is applied to the opposing copper layers 16 and 17. Furthermore, since the interposition of gas molecules at the bonding interface is reduced, the diffusion of copper to be bonded is promoted and the bonding is firmly performed.
On the other hand, the pressing force applied to the aluminum plate 11 and the stainless steel 12 in the region where the vertical interval of the recess 52c is long is reduced, and the copper layers 16 and 17 facing each other are not joined to each other, and are not joined to form a gap. Part 15-1 is formed.

  The composite material 10 formed by the hot press becomes a disc-shaped blank in which an unjoined portion 15-1 of the copper layers 16 and 17 is provided between the aluminum plate 11 and the stainless steel plate 12. The obtained composite material 10 has a strength of 5 to 8 mm with a width of 5 mm and a uniform and stable bonding strength with little unevenness in strength. The thickness (t) of the composite material is about 2.0 mm, but there is almost no variation in the thickness.

The blank is formed by drawing press as an electromagnetic induction heating container 20 having a bottom portion 21 and a peripheral wall 22 as shown in FIG. 6, and the peripheral wall 22 has a continuous unjoined portion 15-1 along the entire circumference. Thus, the gap 15 whose volume is enlarged is located. Further, the fluororesin 18 is located on the inner surface side of the container 20.
It should be noted that the peel strength of a composite plate having a width of 5 mm is 3 kg or more, which is the minimum strength at which problems such as peeling that occur during deep drawing are unlikely to occur, but the composite manufactured by the hot press of the present invention. Since the material 10 has a bonding strength of 6 to 8 kg as described above, it does not cause a problem such as peeling at the time of deep drawing press processing.

  The tensile force in the upper end direction of the peripheral wall 22 is applied to the composite material 10 during the drawing press processing, and the tensile rate of the aluminum plate 11 sandwiching the gap 15 is different from the tensile rate of the stainless steel plate 12. Therefore, at the time of this drawing press processing, the elongation of the aluminum plate 11 is large, the elongation of the stainless steel plate 12 is small, and microscopically, the aluminum plate 11 expands so as to swell with respect to the stainless steel plate 12, and the unjoined portion 15- 1 becomes a gap 15 having a required volume.

  Further, when the scale is printed on the inner surface of the peripheral wall 22 and heated to fix the printing, the thermal expansion coefficient of the aluminum plate 11 and the stainless steel plate 12 is different, and the aluminum plate 11 expands more than the stainless steel plate 12, The volume of the gap 15 is increased, and a gap with a thickness of about 1 mm can be formed.

  As described above, the gap 15 between the stainless steel plate 12 that is a magnetic metal plate that generates heat by electromagnetic induction and the aluminum plate 11 that is a nonmagnetic metal plate that is a heat transfer layer is provided on the entire circumference of the peripheral wall 22. As a result, the heat insulation can be improved. Therefore, the heat retaining property after the heating of the inner pot 20 of the electromagnetic induction heating container can be improved.

FIG. 7 shows a second embodiment, in which one set of aluminum plate 11 and stainless steel plate 12 constituting one composite material 10 is divided into a plurality of sets via upper and lower press dies 51 of a hot press apparatus 50 via a separating material 70. They are stacked in a set space S between 52.
In the second embodiment, stepped protrusions 51a and 52a, 51b and 52b are provided facing the press dies 51 and 52 which are vertically opposed to each other.
Thereby, even if a plurality of sets are set, the metal plate in this region is loaded with a strong pressing force because the stepped protrusions 51a and 52a, 51b and 52b are opposed to each other in the vertical direction, and each set of aluminum plates The copper layers 16 and 17 provided on the entire joining surface where the steel plate 11 and the stainless steel plate 12 face each other can be firmly joined. In addition, in the portion where the stepped protrusions are not provided, the pressing force applied to the aluminum plate 11 and the stainless steel plate 12 is reduced, and the opposing copper layers 16 and 17 do not come into contact with each other, and the gap portion 15 is formed. .
Thus, a plurality of composite materials 10 can be manufactured at a time, and mass production of the composite materials 10 becomes possible.

8A to 8C show a third embodiment, in which a copper plate 30 is interposed as an intermediate metal plate between the aluminum plate 11 and the stainless steel plate 12.
Copper layers 16 and 31 are provided on the opposing joint surfaces of the aluminum 11 and one surface 30a of the copper plate 30, and a copper layer 32 is plated on the opposing joint surfaces of the other surface 30b of the copper plate 30 and the stainless steel plate 12. 17 is provided.

The aluminum plate 11, the copper plate 30, and the stainless steel 12 are laminated in the set space C of the hot press apparatus 50 described in the first embodiment.
When hot pressing is performed in this state, as shown in FIG. 8B, the copper layers 16 and 31, 17 and 32, which are the bonding metal layers, are bonded in the region where the press-shaped stepped protrusions are present. In the region where there is no stepped protrusion, an unjoined portion 15-1A can be formed between the aluminum plate 11 and the copper plate 30, and an unjoined portion 15-B can be formed between the copper plate 30 and the stainless steel plate 12.
That is, it is possible to form the composite material 100 including unjoined portions that become two void portions between different layers.

  When the composite material 100 is formed in the container 20 shown in FIG. 8C having the bottom wall 22 and the peripheral wall 33 by drawing press as in the first embodiment, the peripheral wall 22 has a space between the aluminum plate 11 and the copper plate 30. In addition, the inner circumferential side gap 15 </ b> A can be formed, and the outer circumferential side gap 15 </ b> B can be formed between the copper plate 30 and the stainless steel plate 12.

  In this way, the inner peripheral side gap portion 15A and the outer peripheral side gap portion 15B sealed to the peripheral wall 22 are provided, and the gap portions 15A and 15B are substantially vacuum, so that the heat insulation effect is greatly enhanced. It is possible to improve heat retention.

In any of the above-described embodiments, the aluminum plate of the nonmagnetic metal plate and the stainless steel plate of the magnetic metal plate are punched into a circle and then plated with copper to form a joining metal layer made of a copper layer ( In the third embodiment, the copper plating is performed on both sides of the copper plate of the intermediate metal plate to form a joining metal layer made of a copper layer), but the invention is not limited to the single plating of copper plating, and may be multi-layer plating. However, it is preferable to use the same kind of metal for the uppermost plating layer that is brought into contact with each other, and in particular, copper plating is preferable as described in the embodiment.
In each of the first to third embodiments, each metal plate is formed into a circular shape and then plated to form a joining metal layer. However, after these metal plates are continuously formed and plated, the metal plate is formed into a circular shape. You can skip it.

As described above, the present invention manufactures a composite material by a hot uniaxial pressing method (hot pressing method), and improves the shape of the press die of the hot pressing device, so that the bonding metal is formed on the entire bonding surface. Even if a layer is provided, an unjoined portion that becomes a void portion can be formed.
Therefore, it is not necessary to provide a non-plated portion using a masking sheet as described in Patent Document 1, and the most labor-intensive step can be omitted in the manufacturing process, and productivity can be dramatically improved. .

  Also, the hot press method has low equipment costs and equipment operation costs, and the mold can be used repeatedly, and pressurization and depressurization by the hydraulic press can be performed quickly to shorten the cycle time. In this case, diffusion of metal atoms occurs at the contact interface between the metals for bonding, and the required bonding strength can be obtained almost uniformly without unevenness, and there is almost no reduction in the plate thickness, and thus there is an advantage that the variation in the plate thickness is extremely small. is there.

  Furthermore, the size, shape, and the like of the gap provided between the nonmagnetic metal plate and the magnetic metal plate can be arbitrarily changed. In particular, when the inner pot of the IH jar rice cooker is provided with the void portion of the first embodiment on the entire circumference thereof, the heat retaining property is improved by about 35% compared to the case where the void portion is not provided. Proven. From this point, the electricity bill can be saved while the rice cooker is in the heat insulation mode.

It is a perspective view which shows the composite material of embodiment of this invention. (A) (B) is sectional drawing of the said composite material. It is a schematic sectional drawing of the hot press apparatus which uses the said composite material for manufacture. It is sectional drawing and a top view which show the press die of the said hot press apparatus. It is drawing which shows the manufacturing process of the said embodiment. It is sectional drawing which shows the state which carried out the drawing process of the said composite material, and was set as the container. It is the schematic which shows the state at the time of the hot press of 2nd Embodiment. (A) (B) (C) is drawing which shows 3rd Embodiment. (A) (B) is sectional drawing which shows a prior art example. (A)-(E) are drawings which show the conventional problems.

Explanation of symbols

10 Composite material 11 Aluminum plate (non-magnetic metal plate)
12 Stainless steel plate (magnetic metal plate)
15 Cavity 16, 17 Copper layer (metal layer for bonding)
18 Fluororesin layer 20 Inner pot of electromagnetic induction heating vessel 21 Bottom wall 22 Side wall 28 Joint 30 Copper plate (intermediate metal plate)
50 Hot press device 51, 52 Press mold 52a, 52b Stepped protrusion

Claims (16)

A method for producing a composite material in which a plurality of metal plates to be laminated are joined by a hot uniaxial pressing method (hot press),
The plurality of metal plates to be laminated are a nonmagnetic metal plate and a magnetic metal plate, or a nonmagnetic metal plate and a magnetic metal plate, and one or a plurality of intermediate metals interposed between the nonmagnetic metal plate and the magnetic metal plate. A board,
A metal layer for bonding is previously provided on the entire surface of at least one facing surface of the plurality of metal plates to be laminated,
The plurality of metal plates to be laminated are set between a pair of press dies arranged opposite to each other on both sides in the axial direction of the hot press device, and facing at least one of the press dies toward the opposite press die. Providing a protruding stepped portion,
At the time of hot pressing, the metal plates in the region sandwiched between the stepped protrusion and the counterpart press die are formed as a joint where the joining metal layer is integrally joined, while the region not sandwiched by the projecting step The metal plate is formed as an unjoined portion that becomes a void portion, and is a composite material partially having a void portion.   In the plurality of metal plates to be laminated, the bonding metal layers are arranged to face each other between a plurality of layers, and in a region not sandwiched between the protruding stepped portions, unjoined portions that become gaps between the plurality of layers between the metal plates are formed. The method for producing a composite material according to claim 1, wherein the composite material is a composite material that is formed and has gaps partially at a plurality of locations in the stacking direction of the metal plates.   The bonding metal layer is provided in advance by plating, vapor deposition, ion vapor deposition, molten metal dipping method or molten metal spraying method on the entire surface of the non-magnetic metal plate, magnetic metal plate or intermediate metal plate facing the bonding side. The manufacturing method of the composite material of Claim 1 or Claim 2.   The plurality of metal plates to be stacked as a unit set, a plurality of unit sets are stacked and set between the press dies, and a plurality of composite materials are simultaneously formed. A method for producing the composite material according to item. A method for producing a container having a bottom wall and a peripheral wall by drawing and pressing the composite material produced by the method according to any one of claims 1 to 4,
The metal plates opposed to each other with the integral joint and the non-joint part serving as a gap are formed at the unjoined part due to the difference in tensile rate during the drawing press process. A method for producing a container made of a composite material, characterized in that a gap portion is enlarged, and an enlargement ratio due to tension of the gap portion is set in advance by a tensile ratio of the opposing metal plate. Metal plates facing each other across the unjoined portion that becomes the integral joined portion and the gap portion have different thermal expansion coefficients, and are heated at the required temperature during the drawing press processing or after the drawing press processing,
The gap formed in the unjoined portion is enlarged due to the difference in the thermal expansion coefficient, and the expansion ratio due to the thermal expansion of the gap is preset by the thermal expansion coefficient of the opposing metal plate. The manufacturing method of the composite material of description. The non-magnetic metal plate and the magnetic metal plate are partially joined with a gap interposed therebetween,
The non-magnetic metal plate and the magnetic metal plate are provided with a bonding metal layer on each of the bonding surface sides facing each other,
In the gap, the bonding metal layers are unbonded and face each other with a space therebetween, while the bonding metal layers are bonded in a portion surrounding the gap. . One or a plurality of intermediate metal plates are interposed between the nonmagnetic metal plate and the magnetic metal plate, the opposing surface of the nonmagnetic metal plate and the intermediate metal plate, the opposing surface between the intermediate metal layer plates, the intermediate metal plate and the magnetic metal plate Any one or a plurality of locations on the opposing surface are joined with a gap interposed therebetween,
Each metal plate sandwiching the gap is provided with a joining metal layer,
In the gap, the bonding metal layers are unbonded and are opposed to each other with a gap therebetween, while the bonding metal layers are bonded in a portion surrounding the gap. Wood.   The cross-sectional plate thickness of the composite material in the portion where the gap portion is interposed is larger than the cross-sectional plate thickness of the portion where the bonding metal layers are bonded without interposing the gap portion. The composite material according to claim 8.   It is formed as a circular blank, and is formed as an electromagnetic induction heating container in which the central part is a bottom wall and the outer peripheral part is a peripheral wall by pressing, and the gap is provided in the outer peripheral part that becomes the peripheral wall. The composite material according to any one of claims 7 to 9.   The composite material according to claim 10, wherein the vacuum portion provided in the outer peripheral portion is a concentric annular shape, and is a vacuum portion that continues to the entire circumference of the peripheral wall. The nonmagnetic metal layer is selected from aluminum, aluminum alloy, nonmagnetic stainless steel,
The magnetic metal layer is selected from magnetic stainless steel, iron, iron alloy, nickel, nickel alloy, copper, copper alloy, cobalt, cobalt alloy,
12. The bonding metal layer is made of one or more metal layers selected from copper, aluminum, nickel, silver, and tin, and the bonding metal on the opposite bonding surface is made of the same metal. The composite material according to any one of the above.   The composite material according to any one of claims 7 to 12, produced by the method according to any one of claims 1 to 4.   An electromagnetic induction heating type container manufactured by the method according to claim 5 or 6.   An electromagnetic induction heating type container formed of the composite material according to any one of claims 7 to 12.   A cooking device comprising the electromagnetic induction heating type container according to claim 14 or 15.

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