CN113257557A

CN113257557A - Method for manufacturing metal foil

Info

Publication number: CN113257557A
Application number: CN202110089449.XA
Authority: CN
Inventors: 山下修
Original assignee: Toyota Motor Corp
Current assignee: Toyota Motor Corp
Priority date: 2020-01-24
Filing date: 2021-01-22
Publication date: 2021-08-13
Anticipated expiration: 2041-01-22
Also published as: JP2021118349A; CN113257557B; JP7375708B2

Abstract

The invention provides a method for manufacturing a metal foil, wherein the metal foil composed of an amorphous soft magnetic material can be crystallized into a nanocrystalline soft magnetic material with uniform crystal size by uniformly heating the metal foil. A metal foil (10) made of an amorphous soft magnetic material is brought into close contact with a mounting surface (21) of a metal base (2) in a manner similar to the manner of the mounting surface, and the metal foil (10) is heated while being brought into close contact with the mounting surface (21), whereby the amorphous soft magnetic material as the metal foil (10) is crystallized into a nanocrystalline soft magnetic material. When crystallization is performed, the metal foil (10) is heated at a heating temperature (Tt) which is equal to or higher than the crystallization start temperature (Ts) of the nanocrystalline soft magnetic material and at which the temperature of the mounting surface is lower than the temperature (Ta) of the metal foil which is increased in temperature by self-heating during crystallization, whereby the base (2) absorbs the self-heating heat of the metal foil (10) during crystallization while crystallizing the amorphous soft magnetic material.

Description

Method for manufacturing metal foil

Technical Field

The present invention relates to a method for producing a metal foil made of a nanocrystalline soft magnetic material.

Background

In a conventional motor, transformer, or the like, a laminated body in which metal foils are laminated is used as an iron core (core). For example, patent document 1 proposes a method for producing a metal foil in which a metal foil made of an amorphous soft magnetic material is heated in a state where the metal foil is laminated, thereby crystallizing the amorphous soft magnetic material of the metal foil into a nanocrystalline soft magnetic material.

Prior art documents

Patent document

Patent document 1: japanese patent laid-open publication No. 2017-141508

Disclosure of Invention

Here, it is generally known that an amorphous soft magnetic material is self-heated when the material is crystallized into a nanocrystalline soft magnetic material, and that the self-heating temperature at the time of the self-heating is higher than the temperature at which the crystallization of the material starts. Therefore, for example, as shown in patent document 1, when heating is performed in a state in which metal foils are laminated, heat from the heat is accumulated between the metal foils, and the metal foils may be excessively heated. Further, among the laminated metal foils, the heating temperatures of the inner metal foil and the outer metal foil are also varied. As a result, the crystal size of the metal foil varies.

In view of such problems, it is also conceivable: the metal foils are heated one by one on the heated base (base) without laminating the metal foils. However, for example, when the metal foil is warped, the ratio of the portion of the metal foil not in contact with the base increases, and the temperature of the metal foil may vary during crystallization. In particular, heat is easily accumulated in a gap formed between a portion of the metal foil not in contact with the base and the base, and the temperature of the portion is excessively increased, thereby coarsening crystal grains. As a result, the crystal size of the metal foil varies, and the magnetic properties of the metal foil may be degraded.

The present invention has been made in view of the above problems, and an object thereof is to provide a method for producing a metal foil, in which a metal foil made of an amorphous soft magnetic material can be crystallized into a nanocrystalline soft magnetic material having uniform crystal sizes by uniformly heating the metal foil.

A method for manufacturing a metal foil according to the present invention is a method for manufacturing a metal foil made of a nanocrystalline soft magnetic material, the method including:

preparing a metal foil made of an amorphous soft magnetic material; and

a step of crystallizing an amorphous soft magnetic material as the metal foil into the nanocrystalline soft magnetic material by heating the metal foil while bringing the prepared metal foil into close contact with a base made of metal so that the metal foil follows (follows) the installation surface of the base,

in the crystallization step, the metal foil is heated at a heating temperature which is equal to or higher than a crystallization start temperature of the nanocrystalline soft magnetic material and at which the temperature of the mounting surface is lower than a temperature of the metal foil which is increased in temperature by self-heating during crystallization, whereby the base absorbs the self-heating heat during crystallization while the amorphous soft magnetic material is crystallized.

In the present invention, first, a metal foil made of an amorphous soft magnetic material is prepared. Next, the metal foil in a state of being in close contact with the installation surface is heated while the metal foil is brought into close contact with the installation surface of the metal base in a manner that the metal foil is made to follow the installation surface of the metal base, whereby the amorphous soft magnetic material as the metal foil is crystallized into the nanocrystalline soft magnetic material. At this time, the metal foil is heated at a heating temperature which is not lower than the crystallization starting temperature of the soft magnetic material crystallized into a nanocrystalline state and which is lower than the temperature of the metal foil which is increased in temperature by self-heating at the time of crystallization. Thus, the temperature of the mounting surface of the base is lower than that of the self-heating metal foil while the amorphous soft magnetic material as the metal foil is crystallized, and therefore the base can absorb the self-heating heat from the mounting surface of the base. Here, since the metal foil is in close contact with the base, the heat of the metal foil is uniformly absorbed by the base, and the temperature of the metal foil becomes uniform during crystallization. Therefore, the metal foil crystals can be crystallized in uniform crystals. As a result, the reduction in magnetic properties of the metal foil due to variations in the size of the crystal grains (specifically, coarsening of the crystal grains) can be suppressed.

In the crystallization step, when the metal foil is heated, the metal foil may be heated by heat generated by a heater or heat generated by hot air from a position facing the base through the metal foil, for example. However, in a more preferable aspect, in the crystallization step, the metal foil is heated by a heater built in the base.

According to this aspect, the metal foil can be uniformly heated by the heat of the heater built in the base while the mounting surface of the base is uniformly heated. Further, since the temperature of the mounting surface is lower than the temperature of the metal foil which is self-heating at the time of crystallization and the temperature of the mounting surface is uniform, the base can uniformly absorb the self-heating heat of the metal foil from the mounting surface.

Further, as long as the metal foil can be brought into close contact with the base without warping, for example, a magnet, an electromagnet, or the like may be provided on the base, and the metal foil may be brought into close contact with the base by magnetic force. In a more preferred aspect, in the crystallization step, the metal foil is brought into close contact with the base by sucking the metal foil from a suction port formed in the base.

According to this aspect, by sucking the metal foil from the suction port formed in the base, the warpage of the metal foil can be corrected, and the metal foil can be brought into close contact with the surface of the base without a gap. Even if foreign matter or the like is present on the surface of the base, the foreign matter can be sucked through the suction port, and the foreign matter can be prevented from biting into between the metal foil and the base.

In a more preferred aspect, the metal foil is made of the amorphous soft magnetic material by blowing a molten metal obtained by melting a raw material of the metal foil onto a rotating roll and solidifying the molten metal by cooling the molten metal on the roll, and when the metal foil is brought into close contact with the substrate, a surface of the metal foil on a side in contact with the roll is brought into close contact with the mounting surface.

According to this aspect, the metal foil made of an amorphous soft magnetic material is produced by a method in which a molten metal, which is a raw material of the metal foil, is blown onto a rotating roll and the molten metal is cooled and solidified on the roll, that is, a so-called single roll method. Among the surfaces of the metal foil thus obtained, the surface on the side in contact with the roller has fewer irregularities than the surface on the opposite side, and therefore the surface of the metal foil can be brought into more uniform close contact with the installation surface of the base, and the metal foil can be uniformly heated in this uniformly close contact state. This promotes uniform crystallization of the metal foil, and suppresses uneven plastic deformation due to shrinkage during crystallization, thereby enabling dense lamination of the crystallized metal foil.

In a more preferred aspect, in the step of preparing a metal foil, a metal foil made of an iron-based amorphous soft magnetic material is prepared as the metal foil, and the step of crystallizing is a step of placing the metal foil on a support member, moving at least one of the base and the support member in a direction in which the base and the support member are brought close to each other, sandwiching the metal foil between the base and the support member, thereby bringing the metal foil into close contact with the base, and heating the metal foil by a heater built in the base, and in the step of crystallizing, the following condition (i) or (ii) is satisfied. (i) The thermal conductivity of the material constituting the support member is 0.2W/mK or less. (ii) The temperature of the support member is set to 300 ℃ or higher and less than the crystallization starting temperature.

According to this aspect, the support member on which the metal foil is disposed can be relatively brought close to the base, and therefore the metal foil can be sandwiched between the base and the support member to more uniformly adhere the metal foil to the base.

In this case, the metal foil is heated by a heater built in the base and crystallized, but (i) the thermal conductivity of the material constituting the support member is set to 0.2W/mK or less, so that the support member is less likely to take heat. Specifically, even if the temperature distribution of the mounting surface of the base is uneven when the metal foil is brought into close contact with the metal foil due to the shape of deformation or warpage of the metal foil, the heat of the metal foil is less likely to be taken away by the support member, and the temperature distribution of the metal foil can be made uniform. This can suppress a local temperature decrease in the mounting surface of the base with the metal foil in close contact with the base. As a result, uniform crystallization of the metal foil can be promoted, and uneven plastic deformation due to shrinkage during crystallization can be suppressed, so that the crystallized metal foil can be stacked more densely.

Here, when the thermal conductivity of the material constituting the support member exceeds 0.2W/mK, the heat of the installation surface of the base easily escapes to the support member through the metal foil. Therefore, even if the temperature distribution of the mounting surface of the base is uneven when the metal foil and the base are brought into close contact with each other, the unevenness is hard to be uniform, and the crystallization of the metal foil preferentially starts from a high-temperature portion, and therefore the time point (timing) of shrinkage accompanying the crystallization differs depending on the portion. As a result, the metal foil is deformed unevenly, and the crystallized metal foil may not be laminated densely.

On the other hand, when the metal foil is crystallized by heating with a heater built in the base, even if (ii) the temperature of the supporting member is set to 300 ℃ or higher and lower than the crystallization start temperature of the metal foil, the temperature difference between the base and the supporting member is small, and therefore the heat of the base is hardly taken away by the supporting member. Specifically, even if the temperature distribution of the mounting surface of the base is uneven due to the shape of the metal foil such as undulation, etc., when the base and the metal foil are brought into close contact with each other, the heat of the metal foil is less likely to be taken away by the support member, and the temperature distribution of the metal foil can be made uniform. This can suppress a local temperature decrease in the mounting surface of the base with the metal foil in close contact with the base. As a result, uniform crystallization of the metal foil can be promoted, and uneven plastic deformation due to shrinkage during crystallization can be suppressed, so that the crystallized metal foil can be stacked more densely.

Here, when the temperature of the support member is less than 300 ℃, the heat of the installation surface of the base easily escapes to the support member through the metal foil. Therefore, when there is a variation in the temperature of the mounting surface, the progress of crystallization of the metal foil varies depending on the location according to the variation in the temperature, and therefore the time point of shrinkage associated with crystallization varies depending on the location. As a result, the metal foil is deformed unevenly, and the crystallized metal foil may not be laminated densely. On the other hand, when the temperature of the support member is not lower than the crystallization start temperature of the metal foil, the metal foil may be crystallized when the metal foil is disposed on the support member (that is, before the metal foil is sandwiched between the base and the support member), and the effect of crystallization of the metal foil by the heat of the base may not be obtained.

According to the method for producing a metal foil according to the present invention, a metal foil made of an amorphous soft magnetic material can be crystallized into a nanocrystalline soft magnetic material having uniform crystal size by uniformly heating the metal foil without excessively raising the temperature of the metal foil.

Drawings

Fig. 1 is a schematic perspective view showing a heating apparatus for carrying out a method of manufacturing a metal foil according to an embodiment of the present invention.

Fig. 2 is a sectional view in a view direction at a line a-a of the heating apparatus shown in fig. 1.

Fig. 3 is a schematic perspective view showing a state in which a metal foil is brought into close contact with the heating device shown in fig. 1.

Fig. 4 is a graph showing a temperature profile (profile) of the metal foil shown in fig. 3.

Fig. 5A is a schematic perspective view for explaining a preparation step in the method for manufacturing a metal foil according to the modification.

Fig. 5B is a schematic cross-sectional view of the metal foil manufactured by fig. 5A.

Fig. 6A is a schematic cross-sectional view for explaining a crystallization process of a metal foil using the heating apparatus shown in fig. 1.

Fig. 6B is a schematic cross-sectional view for explaining a state in which the metal foil is heated while being adsorbed to the mounting surface of the base.

Fig. 6C is a schematic cross-sectional view of a modification of fig. 6B.

Fig. 7 is a schematic cross-sectional view to be compared with fig. 6B.

Fig. 8A is a schematic perspective view for explaining a manufacturing process of the rotor core.

Fig. 8B is a schematic perspective view for explaining a manufacturing process of the motor.

Description of the reference numerals

10: a metal foil; 2: a base station; 21: arranging a surface; 22: a suction port; 5: a heater; ta: the temperature of the metal foil; ts: a crystallization start temperature; tt: the temperature is heated.

Detailed Description

Hereinafter, a method for manufacturing a metal foil according to the present invention will be described with reference to the drawings. In fig. 1 to 4, the metal foil used will be described, and then the manufacturing method in each embodiment will be described.

1. With respect to the metal foil 10

The metal foil produced in this embodiment is a metal foil made of a nanocrystalline soft magnetic material. In the following manufacturing method, a metal foil made of an amorphous soft magnetic material is prepared, and the amorphous soft magnetic material is crystallized into a nanocrystalline soft magnetic material by heat treatment, thereby manufacturing the metal foil.

Here, an amorphous soft magnetic material and a nanocrystalline soft magnetic material constituting the metal foil will be described. Examples of the amorphous soft magnetic material and the nanocrystalline soft magnetic material include, but are not limited to, materials composed of at least 1 magnetic metal selected from Fe, Co, and Ni, and at least 1 nonmagnetic metal selected from B, C, P, Al, Si, Ti, V, Cr, Mn, Cu, Y, Zr, Nb, Mo, Hf, Ta, and W.

Typical examples of the amorphous soft magnetic material and the nanocrystalline soft magnetic material include, but are not limited to, FeCo-based alloys (e.g., FeCo and FeCoV), FeNi-based alloys (e.g., FeNi, FeNiMo, FeNiCr, and FeNiSi), FeAl-based alloys, FeSi-based alloys (e.g., FeAl, FeAlSi, FeAlSiCr, FeAlSiTiRu, and FeAlO), FeTa-based alloys (e.g., FeTa, FeTaC, and FeTaN), and FeZr-based alloys (e.g., FeZrN). In the case of the Fe-based alloy, it is preferable to contain 80 at% or more of Fe.

As another material of the amorphous soft magnetic material or the nanocrystalline soft magnetic material, for example, a Co alloy containing Co and at least 1 selected from Zr, Hf, Nb, Ta, Ti, and Y can be used. The Co alloy preferably contains 80 at% or more of Co. Such a Co alloy is likely to be amorphous during film formation, and exhibits very excellent soft magnetism because of little crystal magnetic anisotropy, crystal defects, and grain boundaries. Examples of suitable amorphous soft magnetic materials include CoZr, CoZrNb, and CoZrTa alloys.

The amorphous soft magnetic material referred to in this specification is a soft magnetic material having an amorphous structure as a main structure. In the case of an amorphous structure, no distinct peak is seen in the X-ray diffraction spectrum, and only a broad halo (halo) pattern is observed. On the other hand, a nanocrystalline structure can be formed by heat treatment of an amorphous structure, but in a nanocrystalline soft magnetic material having a nanocrystalline structure, a diffraction peak is observed at a position corresponding to the lattice spacing of a crystal plane. The crystallite diameter can be calculated from the width of the diffraction peak by using the Scherrer formula.

In the nanocrystalline soft magnetic material referred to in the present specification, the nanocrystalline means a crystal having a crystallite diameter of less than 1 μm, which is calculated from the Scherrer equation based on the full width at half maximum of the diffraction peak of X-ray diffraction. In the present embodiment, the crystallite diameter of the nanocrystal (crystallite diameter calculated from Scherrer's formula based on the full width at half maximum of the diffraction peak of X-ray diffraction) is preferably 100nm or less, and more preferably 50nm or less. The crystallite diameter of the nanocrystal is preferably 5nm or more. By making the crystallite diameter of the nanocrystal such a size, improvement in magnetic properties can be observed. Further, the crystallite diameter of a conventional electrical steel sheet is on the order of micrometers (μm), and is generally 50 μm or more.

The amorphous soft magnetic material can be obtained by melting a metal raw material blended so as to have the above-described composition at a high temperature in a high-frequency melting furnace or the like to obtain a uniform melt and rapidly cooling the melt. The quench rate also depends on the material, e.g. about 10⁶The quenching rate is not particularly limited if an amorphous structure can be obtained before crystallization. In the present embodiment, the metal foil described later can be obtained by blowing a molten metal material onto a rotating cooling roll to produce a metal foil strip made of an amorphous soft magnetic material and forming the metal foil strip into a desired shape by blanking molding or the like. By rapidly cooling the melt in this manner, a soft magnetic material having an amorphous structure can be obtained before the material is crystallized. The thickness of the metal foil is, for example, in the range of 10 μm to 100 μm, preferably 20 μm to 50 μm.

In the drawings described below, the metal foil 10 is rectangular, but the shape is not limited to this. For example, the metal foil may be a fan-shaped metal foil corresponding to the shape of the rotor core of the motor. The metal foil 10 is obtained by forming a strip of an amorphous soft magnetic material by blanking molding or the like, and the metal foil 10 may be warped by such forming as shown in fig. 1. With respect to the metal foil 10 having the warpage in this manner, the metal foil 10 made of a nanocrystalline soft magnetic material can be preferably manufactured by the heating apparatus 1 shown in fig. 1.

2. Heating device 1 for metal foil 10

The heating device 1 is a device that heats the metal foil 10, and includes a base (base) 2 on which the metal foil 10 is provided, a suction device 3 that sucks the metal foil 10 provided on the base 2, and a plurality of heaters 5, … that heat the metal foil 10 via the base 2.

The base 2 is preferably made of a material having higher thermal conductivity than the heated metal foil 10, and when the metal foil 10 is an Fe-based amorphous alloy, it is preferably made of a metal material such as an aluminum alloy or a copper alloy. An installation surface 21 on which the metal foil 10 is installed is formed on the base 2. In the present embodiment, the installation surface 21 is a flat surface, but the shape of the installation surface 21 is not particularly limited as long as it is a shape corresponding to the shape of the heated metal foil 10.

In the present embodiment, a plurality of suction ports 22, … are formed in the installation surface 21, and these suction ports 22, … communicate with each other through a suction passage 23 formed in the base 2. The suction device 3 is connected to the other end of the suction passage 23 through a pipe 8 with respect to the suction ports 22, …. The suction device 3 may be, for example, a suction (suction) pump or the like, and may be, for example, a vacuum aspirator (not shown) for sucking the metal foil 10 by reducing the pressure in the pipe 8 and the suction passage 23.

As shown in fig. 2, a housing portion 25 for housing each heater 5 is formed in the base 2. In the present embodiment, the housing portion 25 is provided on the side opposite to the installation surface 21 with the suction passage 23 interposed therebetween. In the present embodiment, since the heater 5 is a rod-shaped heater 5, the housing portion 25 is a hollow extending in one direction, and one end thereof is open. The heater 5 is inserted into the housing 25 of the base 2 from the opened portion.

In the present embodiment, the heater 5 is a resistance heating rod-shaped heater, and is connected to a power supply (not shown) via a wire 51. The heater 5 is built in the base 2. Specifically, the heater 5 is housed in the housing portion 25 of the base 2. In the present embodiment, the heater 5 is a rod-shaped heater, but the shape of the heater 5 is not particularly limited as long as the installation surface 21 of the base 2 can be uniformly heated, and may be a planar heater.

In the present embodiment, base 2 and metal foil 10 are heated by the resistance of heater 5, but base 2 and metal foil 10 may be heated by, for example, induction heating or heating with a heat medium. Alternatively, the heater 5 may be provided outside the base 2 to heat the base 2 from the outside.

3. Method for manufacturing metal foil 10

The metal foil 10 is heated by using the heating apparatus 1 shown in fig. 1 and 2. First, in the present embodiment, metal foil 10 made of an amorphous soft magnetic material is provided on installation surface 21 of metal base 2. At this time, the metal foil 10 is provided so as to cover the suction ports 22, … formed in the installation surface 21.

Next, the metal foil 10 made of an amorphous soft magnetic material is brought into close contact with the mounting surface 21 of the base 2. Specifically, after the metal foil 10 is provided, the suction device 3 is operated. Thereby, the inside of the pipe 8 and the suction passage 23 are in a reduced pressure state, and the metal foil 10 can be sucked from the plurality of suction ports 22, …. In the present embodiment, by sucking the metal foil 10 through the plurality of

suction ports

22 and 22 …, the metal foil 10 having a warped shape, for example, can be made to follow the planar installation surface 21 as shown in fig. 3, and the shape can be corrected to bring the metal foil 10 into close contact with the installation surface 21 of the base 2. Even if foreign matter or the like is present on the installation surface 21 of the base 2, the foreign matter can be sucked through the suction port 22, and the foreign matter can be prevented from biting into between the metal foil 10 and the base 2.

Next, the metal foil 10 in a state of being in close contact with the base 2 is heated, whereby the amorphous soft magnetic material as the metal foil 10 is crystallized into the nanocrystalline soft magnetic material. Specifically, the metal foil 10 is heated at a heating temperature which is not lower than the crystallization starting temperature of the soft magnetic material crystallized into the nanocrystalline material and at which the temperature of the mounting surface 21 is lower than the surface temperature of the metal foil 10 which is increased in temperature by self-heating at the time of crystallization. This crystallizes the amorphous soft magnetic material as the metal foil 10 into a nanocrystalline soft magnetic material, and causes the base 2 to absorb the self-heating heat of the metal foil 10 during the crystallization.

Here, the conditions for the heat treatment of the metal foil 10 are not particularly limited as long as they are heat treatment conditions that can crystallize the material and can absorb the heat of the metal foil 10 in the self-heating process of the base 2, and they may be appropriately selected in consideration of the composition of the metal material, the magnetic properties to be exhibited, and the like. The heat treatment is preferably performed under an inert gas atmosphere.

Here, the lower limit of the heating temperature for heating the metal foil 10 is the crystallization start temperature at which the amorphous soft magnetic material starts to crystallize into the nanocrystalline soft magnetic material. The "crystallization start temperature" is a temperature at which crystallization occurs with respect to the amorphous soft magnetic material.

Since an exothermic reaction occurs during crystallization, the crystallization start temperature can be determined by measuring the temperature at which heat is generated as the metal foil 10 is crystallized. For example, Differential Scanning Calorimetry (DSC) can be used to determine a predetermined heating rate (e.g., 0.67 Ks)^-1) The crystallization temperature was measured under the conditions of (1). The crystallization starting temperature of the amorphous soft magnetic material varies depending on the material, etc., but when the material is an Fe-based amorphous alloy, it is, for example, in the range of 400 ℃ to 450 ℃.

Here, when the metal foil 10 is heated from room temperature to a temperature lower than the crystallization start temperature by the heat transferred from the mounting surface 21, the heat of mc Δ T is retained in the metal foil 10 as sensible heat. Here, m is the mass of the metal foil 10, c is the specific heat of the material of the metal foil 10, and Δ T is the temperature rise width. Further, a part of the input heat Δ Qout is radiated from the exposed surface of the metal foil 10. In addition, "Δ" in this specification means per unit time.

Here, as shown in fig. 4, when the metal foil 10 is heated to the crystallization start temperature Ts or more, the metal foil 10 is self-heated by crystallization. At this time, heat Δ Qself due to self-heating is generated in the metal foil 10.

For example, when the heating temperature Tt of the base 2 (specifically, the temperature of the mounting surface 21) is set to the same temperature as the crystallization start temperature Ts, the metal foil 10 self-heats. Therefore, the heat amount Δ Qself due to the self-heating of the metal foil 10 is generated, the metal foil 10 is heated to a temperature higher than the crystallization start temperature Ts, and the temperature increase rate of the metal foil 10 is increased.

In this case, the temperature Ta of the metal foil 10 becomes higher than the temperature (heating temperature Tt) of the mounting surface 21 of the base 2. Therefore, although the base 2 is heated by the heater 5, the self-heated metal foil 10 serves as a heat source, and heat generated by the self-heating is absorbed by the base 2 from the mounting surface 21.

When the temperature of the mounting surface 21 of the base 2 (specifically, the heating temperature Tt) is set to a temperature higher than the crystallization start temperature Ts, the metal foil 10 is self-heated from a time point at which the temperature becomes equal to or higher than the crystallization start temperature Ts, and therefore, the heat amount Δ Qself due to the self-heating of the metal foil 10 is generated.

Here, the temperature of the metal foil 10 is further raised in accordance with the amount of heat Δ Qself generated by the spontaneous heat from the time point when the temperature of the metal foil 10 becomes equal to or higher than the crystallization start temperature Ts, but when the heating temperature Tt is higher than the temperature Ta of the metal foil 10 at the time of the spontaneous heat generation, heat is continuously input from the mounting surface 21 to the metal foil 10. Therefore, in such a case, the self-heating heat of the metal foil 10 cannot be absorbed from the mounting surface 21 to the base 2.

From such a viewpoint, the upper limit value of the heating temperature Tt (the temperature of the mounting surface 21) for heating the metal foil 10 is set to a temperature lower than the temperature Ta of the metal foil 10 which is increased in temperature by self-heating when crystallization is performed in a state where the metal foil 10 is mounted on the base 2. The upper limit of the heating temperature Tt varies depending on the material, etc., but when the material is an Fe-based amorphous alloy, it is preferably higher than the crystallization start temperature Ts by, for example, 30 to 100 ℃.

By setting the heating temperature Tt in such a range, the temperature Ta of the metal foil 10 at the time of self-heating becomes higher than the crystallization start temperature Ts, and becomes higher than the heating temperature Tt during the period L2 in the period L1 in which the metal foil 10 is heated at the heating temperature Tt equal to or higher than the crystallization temperature Ts. That is, a period L2 from a time point A3 at which the temperature Ta of the metal foil 10 exceeds the heating temperature Tt to a time point a2 at which the crystallization of the metal foil 10 is completed, among periods L1 from a time point a1 at which the temperature Ta of the metal foil 10 reaches the crystallization start temperature Ts to a time point a2 at which the crystallization of the metal foil 10 is completed, is a period during which the base 2 absorbs heat of the self-heating of the metal foil 10. The time point a2 at which the crystallization of the metal foil 10 is completed is a time point at which the nanocrystals of the metal foil 10 fall within a predetermined range of crystal grain sizes.

The temperature of the metal foil 10, which is increased in temperature by self-heating, can be calculated by a general thermal calculation from the amount of heat input to the metal foil 10, the amount of heat of sensible heat held by the metal foil 10, the amount of heat radiated from the surface of the metal foil 10, the amount of heat generated by self-heating of the metal foil 10, the amount of heat absorbed from the metal foil 10 to the mounting surface 21, the thermal contact resistance between the metal foil 10 and the mounting surface 21, and the like. In addition, the temperature of the metal foil 10 which is increased in temperature by self-heating can be experimentally obtained by actually changing the heating temperature Tt of the mounting surface 21.

In this way, in the period L1 in which the metal foil 10 is heated at the heating temperature Tt equal to or higher than the crystallization temperature Ts, there may be a period L2 in which the temperature Ta of the metal foil 10 at the time of self-heating becomes higher than the heating temperature Tt. Accordingly, since there is a period L2 in which the amount of heat absorbed from the metal foil 10 to the mounting surface 21 is greater than the amount of heat generated spontaneously by the metal foil 10, the heat generated by the metal foil 10 can be absorbed by the base 2 during this period L2.

As described above, according to the present embodiment, the amorphous soft magnetic material as the metal foil 10 is crystallized into the nanocrystalline soft magnetic material by heating the metal foil 10 in a state of being in close contact with the mounting surface 21 of the base 2. At this time, by setting the heating temperature Tt to the above temperature, the amorphous soft magnetic material as the metal foil 10 is crystallized, and at the same time, the base 2 can absorb heat from the metal foil 10 that has been heated from the mounting surface 21 of the base 2.

Since the metal foil 10 is in close contact with the base 2, the heat of the metal foil 10 is uniformly absorbed by the base 2, and the temperature of the metal foil 10 becomes uniform during crystallization. Therefore, the crystals of the metal foil 10 can be crystallized and formed in uniform-sized crystals. As a result, the reduction in the magnetic properties of the metal foil 10 due to the variation in the size of the crystal grains (specifically, the coarsening of the crystal grains) can be suppressed.

In particular, in the present embodiment, since the metal foil 10 is heated by the heater 5 incorporated in the base 2, the metal foil 10 can be uniformly heated by the heat of the heating while the mounting surface 21 of the base 2 is uniformly heated by the heater 5 incorporated in the base 2. Further, since the temperature of the mounting surface 21 is lower than the temperature of the metal foil 10 that is self-heated at the time of crystallization, and the temperature of the mounting surface 21 is uniform, the heat of the metal foil 10 that is self-heated can be uniformly absorbed from the mounting surface 21 by the base 2.

Here, the metal foil 10 may be prepared in advance by using the forming apparatus 20 shown in fig. 5A, and the details thereof will be briefly described below with reference to fig. 5A, as described above. In the present embodiment, the molding apparatus 20 includes a crucible 50 and a columnar cooling roll 60, and molds the metal foil 10 by a liquid quenching method. The liquid quenching method may be a single-roll method, a twin-roll method, a centrifugal method, or the like, and in the present embodiment, a single-roll method is employed in which the molten metal M is supplied onto one cooling roll 60 rotating at a high speed and is rapidly solidified to obtain the strip-shaped metal foil 10A from the viewpoint of productivity and maintainability.

The crucible 50 shown in fig. 5A is provided with a high-frequency heating heater (not shown), and the metal serving as a starting material of the metal foil 10 is heated by the high-frequency heating heater to become the molten metal M. The composition of the molten metal M is as described above. Here, the crucible 50 corresponds to the high-frequency melting furnace described above.

A spout 51 for spouting the molten metal M in the crucible 50 is formed below the crucible 50. The ejection port 51 has a slit-like shape, and is disposed on the circumferential surface of the cooling roll 60 so as to extend in the axial direction of the cooling roll 60. The cooling roll 60 is a copper roll, and is connected to a motor (not shown) and rotationally driven. A cooling mechanism in which a coolant flows is provided inside the cooling roller 60. Further, a pressure adjusting device (not shown) for adjusting the amount of molten metal M blown out (i.e., the amount of molten metal M blown out) from the nozzle is provided upstream of the crucible 50.

In manufacturing the metal foil 10, a molten metal M obtained by melting a raw material of the metal foil 10 is blown onto the circumferential surface of the rotating cooling roll 60, and the molten metal M is cooled and solidified on the circumferential surface of the cooling roll 60. By rapidly cooling the molten metal M by the cooling roll 60, the molten metal M is not crystallized, and the strip-shaped metal foil 10 made of the amorphous soft magnetic material can be obtained. The obtained metal foil 10A in a band shape is formed into a desired shape by cutting, blanking, or the like, and the obtained metal foil 10 is heated by, for example, the heating apparatus 1 shown in fig. 1 or the like.

As shown in fig. 5A and 5B, the surface 10A of the obtained metal foil 10A (10) that is in contact with the cooling roller 60 has a flat surface corresponding to the shape of the surface of the columnar cooling roller 60. On the other hand, of the surfaces of the obtained metal foil 10, the surface 10b opposite to the surface 10a in contact with the cooling roller 60 is formed with irregularities due to variations in the amount of adhesion of the molten metal M on the cooling roller 60. Then, in the present embodiment, as shown in fig. 6A and 6B, the metal foil 10 is heated by using the heating device 1A.

The heating device 1A shown in fig. 6A and 6B is similar to the heating mechanism shown in fig. 1 and 2, but in the heating device 1A shown in fig. 6A and 6B, it is arranged upside down such that the installation surface 21 of the base 2 faces downward. The heating device 1A further includes a support member 30 at a position facing the installation surface 21 of the base 2. The base 2 and the support member 30 are mounted with a moving device (not shown) that moves at least one of them so that the base 2 and the support member 30 relatively approach and separate.

In the present embodiment, as shown in fig. 6A and 6B, when the metal foil 10 is brought into close contact with the base 2, the surface 10a of the surface of the metal foil 10 on the side in contact with the cooling roller 60 is brought into close contact with the installation surface 21. Specifically, as shown in fig. 6A, in the present embodiment, the metal foil 10 is disposed on the support member 30 such that the surface 10a of the metal foil 10 faces the base 2. That is, the metal foil 10 is disposed on the support member 30 such that the surface 10b of the metal foil 10 opposite to the surface 10a is in contact with the support member 30.

Next, as shown in fig. 6B, at least one of the base 2 and the support member 30 is moved to a position where the metal foil 10 can be sucked through the plurality of suction ports 22, and … so that the base 2 and the support member 30 are brought close to each other. That is, in the present embodiment, the metal foil 10 is not sandwiched between the base 2 and the support member 30. Therefore, the shape of the metal foil 10 is not corrected by the base 2 and the support member 30, but corrected by suction through the plurality of suction ports 22, …, and the surface 10b on the opposite side of the metal foil 10 is exposed to the atmosphere without the metal foil 10 being pressed by the base 2 and the support member 30. This can suppress uneven heating of the metal foil 10 due to variations in the pressure distribution of the metal foil 10 under pressure.

For example, as shown in fig. 7, when the surface 10b on the opposite side of the metal foil 10 is brought into close contact with the installation surface 21 of the base 2, the surface may not be brought into close contact with the installation surface uniformly (a part of the surface may float) in the process, although the degree of unevenness of the surface 10b depends. The heat of the base 2 crystallizes from the portion 10C in close contact therewith, and the portion 10C shrinks, while the portion 10d which is not in close contact with the gap C locally crystallizes later and shrinks. Due to uneven shrinkage caused by such crystallization, the metal foil may be unevenly plastically deformed. The partially non-close-contact portion 10d is brought into close contact with the base 2 later than the close-contact portion 10 c.

However, the surface 10a of the surface of the metal foil 10 on the side contacting the cooling roller 60 is flat, and as shown in fig. 6B, by bringing the surface 10a into close contact with the installation surface 21 of the base 2, the metal foil 10 can be brought into close contact with the installation surface 21 uniformly. Therefore, the metal foil 10 can be uniformly heated and crystallized as compared with the case of fig. 7. As a result, uniform crystallization of the metal foil 10 can be promoted, and occurrence of uneven plastic deformation due to deformation caused by shrinkage during crystallization can be suppressed, so that the crystallized metal foil 10 can be stacked more densely. When the heating apparatus 1 shown in fig. 1 is used, the surface 10a of the metal foil 10 may be disposed on the installation surface 21 of the base 2.

In the crystallization step, the heating apparatus 1B shown in fig. 6C may be used. The base 2 of the heating device 1B is not provided with a suction port, and the heater 5 is incorporated in the base 2 as in fig. 6A. A moving device (not shown) that moves in a direction in which the base 2 and the support member 30 approach each other to a position in which the metal foil 10 can be sandwiched between the base 2 and the support member 30 is connected to at least one of the base 2 and the support member 30.

In the present embodiment, the metal foil 10 is arranged on the support member 30, and the base 2 and the support member 30 are moved in the direction of relatively approaching each other, whereby the metal foil 10 is sandwiched between the base 2 and the support member 30. The metal foil 10 is held in close contact with the base 2 by the sandwiching, and the metal foil 10 is heated by the heater 5 built in the base 2.

Here, as long as the metal foil 10 can be uniformly heated, any surface of the metal foil 10 that is in contact with the base 2 may be used. However, in the case of manufacturing the metal foil 10 by the single-roll method, the surface 10a of the metal foil 10 on the side in contact with the cooling roll 60 is preferably brought into close contact with the installation surface 21 for the same reason as described above.

Further, in the heating apparatus 1 shown in fig. 1, the suction port is provided in the base 2, but for example, in the heating apparatus 1B shown in fig. 6C, the suction port shown in fig. 1 may be provided in either one of the base 2 and the supporting member 30 to suck the metal foil 10. When the support member 30 is provided with the suction port, the deformation such as warpage of the metal foil 10 can be strongly corrected by the suction through the suction port at the stage when the metal foil 10 is already mounted on the support member 30. On the other hand, when the suction port is provided in the base 2, when the support member 30 on which the metal foil 10 is disposed is brought close to the base 2, the metal foil 10 is attracted to the installation surface 21 of the base 2, and the attracted metal foil 10 is sandwiched between the support members 30 and pressurized.

Here, regardless of the surface of the metal foil 10 that contacts the base 2, when the shape of the metal foil 10 is a slightly warped shape or a wavy shape, the metal foil 10 may be unevenly heated when the metal foil 10 is heated by the heating device 1B shown in fig. 6C. In view of such a point, the present inventors have found the following point as is clear from the experiments described later.

Specifically, in the crystallization step, when the heating apparatus 1B shown in fig. 6C is used, the following condition (i) or (ii) is preferably satisfied.

(i) The thermal conductivity of the material constituting the support member 30 is 0.2W/mK or less.

(ii) The temperature of the support member 30 is set to 300 ℃ or higher and lower than the crystallization starting temperature.

The metal foil 10 is heated by the heater 5 incorporated in the base 2 in a state where the metal foil 10 is sandwiched between the base 2 and the support member 30, and the metal foil 10 is crystallized, but (i) the thermal conductivity of the material constituting the support member 30 is 0.2W/mK or less, so that heat is hardly taken away by the support member 30.

Specifically, even if the uneven temperature distribution of the installation surface 21 of the base 2 occurs when the metal foil 10 is brought into close contact with the metal foil 10 due to the undulated shape (wavy shape) or the warped shape of the metal foil 10 caused by blanking, cutting, or the like, the heat of the metal foil 10 is less likely to be taken away by the support member 30. This facilitates heat retention between the metal foil 10 and the support member 30, and therefore makes it possible to uniformize the temperature distribution of the metal foil 10.

This can suppress a local temperature decrease in the mounting surface 21 of the base 2 in a state where the metal foil 10 is in close contact with the base 2. As a result, uniform crystallization of the metal foil 10 can be promoted, and occurrence of uneven plastic deformation due to deformation caused by shrinkage during crystallization can be suppressed, so that the crystallized metal foil 10 can be stacked more densely.

As is clear from the later-described embodiment, when the thermal conductivity of the material constituting the support member 30 exceeds 0.2W/mK, the heat of the installation surface 21 of the base 2 is easily dissipated to the support member via the metal foil. Therefore, even if unevenness or the like occurs in the temperature distribution of the mounting surface 21 of the base 2 when the metal foil 10 is brought into close contact with the base, the unevenness is less likely to become uniform, and the crystallization of the metal foil 10 starts from a high-temperature portion, and therefore the time point of shrinkage associated with the crystallization differs depending on the portion. As a result, uneven plastic deformation of the metal foil 10 occurs, and the crystallized metal foil 10 may not be laminated densely.

Here, as the material constituting the support member 30, calcium silicate, gypsum, PVC, acrylic resin, or the like can be mentioned as a material satisfying the condition that the thermal conductivity is 0.2W/mK or less.

On the other hand, when the metal foil 10 is crystallized by being heated by the heater 5 built in the base 2, (ii) even if the temperature of the supporting member 30 is set to 300 ℃ or more and less than the crystallization start temperature of the metal foil, the heat of the base is less likely to be taken away by the supporting member because the temperature difference between the base 2 and the supporting member 30 is small.

Specifically, even if the temperature distribution of the mounting surface 21 of the base 2 is uneven when the metal foil 10 is brought into close contact with the metal foil 10 due to the shape of the metal foil 10 such as warpage, the heat of the metal foil 10 is less likely to be taken away by the support member 30, and the temperature distribution of the metal foil 10 can be made uniform.

As is clear from the embodiment described later, when the temperature of the support member 30 is less than 300 ℃, the heat of the installation surface 21 of the base 2 is easily dissipated to the support member 30 through the metal foil 10. Therefore, when there is a variation in the temperature of the mounting surface 21, the progress of crystallization of the metal foil 10 varies depending on the location according to the variation in the temperature, and therefore the time point of shrinkage associated with crystallization varies depending on the location. As a result, the metal foil 10 is plastically deformed unevenly, and the crystallized metal foil 10 may not be laminated densely. On the other hand, when the temperature of the support member 30 is equal to or higher than the crystallization start temperature of the metal foil 10, the metal foil 10 may be crystallized when the metal foil 10 is already disposed on the support member 30 (that is, before the metal foil is sandwiched between the base 2 and the support member 30), and the effect of crystallization of the metal foil 10 by the heat of the base 2 may not be obtained.

In the crystallization step, when the heating apparatus 1B shown in fig. 6C is used, the following conditions are more preferably further satisfied. Specifically, in the crystallization step, at least one of the base 2 and the support member 30 is moved at a moving speed of 125 mm/sec or more in a direction in which the base 2 and the support member 30 approach each other, and the metal foil 10 is sandwiched between the base 2 and the support member 30. This allows the metal foil 10 to instantaneously contact the installation surface 21 of the base 2, and the timing (time) at which each part of the metal foil 10 is heated by the installation surface 21 of the base 2 can be made close. As a result, the metal foil 10 can be heated more uniformly, so that uniform crystallization of the metal foil 10 can be promoted, and uneven plastic deformation due to shrinkage during crystallization can be suppressed. Therefore, the crystallized metal foil 10 can be stacked more densely.

Here, when the moving speed between the base 2 and the support member 30 is less than 125 mm/sec, there may be a portion which locally starts heating by contacting the base 2 as compared with other portions, and the time point of shrinkage accompanying crystallization may vary depending on the portion. As a result, the metal foil 10 is plastically deformed unevenly, and the crystallized metal foil 10 may not be laminated densely.

In the present embodiment, the rectangular metal foil 10 is manufactured, but for example, in the case of manufacturing a stator of an electric motor, a fan-shaped metal foil in which a stator core is divided in the circumferential direction around the rotation axis of the electric motor is prepared and heated to manufacture a metal foil made of a nanocrystalline soft magnetic material. Next, the metal foils 10 are brought into close contact with each other at a predetermined pressure, whereby the laminate 10A is formed. At this time, the metal foils 10 may be bound to each other by a resin such as an adhesive.

Then, as shown in fig. 8A, the laminated body 10A is laminated into a stator core, and the laminated body 10A is fixed, thereby producing a stator core 80A. In fig. 8A and 8B, the detailed shapes of the teeth of the stator core are omitted.

Finally, as shown in fig. 8B, an assembly process is performed. In this step, a stator 80 is formed by arranging coils (not shown) on teeth (not shown) of a stator core, and the stator 80 and the rotor 70 are arranged in a housing (not shown), thereby manufacturing the motor 100.

Examples

The method for producing a metal foil according to the present embodiment will be described in more detail below with reference to examples and comparative examples.

[ example 1]

First, a metal foil (nanome manufactured by northeast マグネットインスティテュート, ltd.) made of an amorphous soft magnetic material (Fe-based amorphous alloy) having a thickness of 25 μm by a general method was prepared. The crystallization initiation temperature of the metal foil was 419.19 ℃. The metal foil was closely attached to the surface of a hot plate heated to 500 ℃ for 1 second. That is, the heating temperature of the metal foil was 500 ℃. The obtained metal foil is crystallized into a nanocrystalline soft magnetic material, the saturation magnetic flux density is in the range of 1.76-1.73T, and the coercive force is in the range of 8-10A/m.

Comparative example 1

A metal foil was produced in the same manner as in example 1. The differences from example 1 are: the metal foil is heated without being attracted and without a part of the metal foil being in contact with the heating plate. The obtained metal foil was crystallized into a nanocrystalline soft magnetic material, but the temperature of the portion of the metal foil not in contact with the hot plate was excessively increased, and coarsening of crystals was confirmed. The saturation magnetic flux density was 1.74T, and the coercive force was 3751A/m. When a motor is formed using a metal foil having such characteristics, it can be said that a loss of torque becomes large.

Thus, in the case of comparative example 1, the portion of the metal foil not in contact with the hot plate was heated to about 800 ℃ by the self-heating of the metal foil. As a result, fine crystals as in the case of the metal foil of example 1 could not be obtained, and the coercivity was higher than that of example 1.

[ example 2-1]

The metal foil was heated in the same manner as in example 1. Specifically, first, a strip-shaped metal foil 10A was produced as an amorphous soft magnetic material (Fe-based amorphous alloy, specifically, Fe — Ni — B-based amorphous alloy) having a thickness of 25 μm using a forming apparatus 20 shown in fig. 5A. A plurality of annular metal foils 10 having an outer diameter of 50.4mm and an inner diameter of 30mm were formed by blanking from the obtained strip-shaped metal foil 10A. Next, as shown in fig. 6B, the metal foil 10 is heated while bringing the surface 10a of the metal foil 10 on the side in contact with the cooling roller 60 into close contact with the mounting surface 21 of the base 2 heated to 500 ℃. A laminate in which 400 metal foils 10 were laminated was produced. The dimension in the layer thickness direction of the laminate was measured as the thickness of the laminate, and the value obtained by dividing the measured thickness of the laminate by the thickness of the laminate when the density was 100% and multiplying by 100 was calculated as the space factor of the laminate. The results are shown in table 1.

[ examples 2-2]

A laminate was produced in the same manner as in example 2-1. The points different from example 2-1 are: as shown in fig. 6C, the metal foil 10 is heated by the heating device 1B. In example 2-2, the support member 30 made of steel was provided with a plurality of suction ports to suck the metal foil 10, and the metal foil 10 was sandwiched between the support member 30 and the base 2 with the shape thereof corrected. The fill factor of the obtained laminate was calculated in the same manner as in example 2-1. The results are shown in table 1. In example 2-2, the metal foil 10 was heated while the surface 10a of the metal foil 10 on the side contacting the cooling roller 60 was brought into close contact with the mounting surface 21 of the base 2.

[ examples 2 to 3]

A laminate was produced in the same manner as in example 2-1. The points different from example 2-1 are: as shown in fig. 7, the metal foil 10 is heated while the surface 10b of the metal foil 10 on the side not in contact with the cooling roller 60 is brought into close contact with the installation surface 21 of the base 2. The fill factor of the obtained laminate was calculated in the same manner as in example 2-1. The results are shown in table 1.

[ examples 2 to 4]

A laminate was produced in the same manner as in example 2-2. The points different from example 2-2 are: the metal foil 10 is heated by the heating device 1B shown in fig. 6C while the surface 10B of the metal foil 10 on the side not in contact with the cooling roller 60 is brought into close contact with the installation surface 21 of the base 2. The fill factor of the obtained laminate was calculated in the same manner as in example 2-1. The results are shown in table 1.

TABLE 1

	Space factor of laminated body
		Example 2-1	96.5％
Examples 2 to 2	95.7％
		Examples 2 to 3	95.5％
Examples 2 to 4	95.4％

The lamination fill factor was reduced in the order of example 2-1 to example 2-4. The reason why the lamination body of example 2-1 has the highest space factor is considered that the surface 10a on the side in contact with the cooling roller 60 is flat, and the surface 10a is uniformly brought into close contact with the base 2 as a heat source. In addition, in example 2-1, it is considered that since the surface 10b on the side not in contact with the cooling roller 60 is exposed to the atmosphere without being in contact with a material having higher thermal conductivity than the atmosphere, such as a support member, heat from the base 2 is uniformly transferred to the metal foil 10.

The reason why the lamination body of example 2-2 has a lower space factor than the lamination body of example 2-1 is considered that the heat from the base 2 is locally dissipated to the supporting member 30 via the metal foil 10 by sandwiching the metal foil 10 between the base 2 and the supporting member 30, and the heat transfer to the metal foil 10 becomes uneven.

Further, in examples 2 to 3 and 2 to 4, since the surface (surface having irregularities) 10b of the metal foil 10 on the side not in contact with the cooling roller 60 was in contact with the base 2 as the heat source, the heat transfer to the metal foil 10 was considered to be uneven. It is considered that the uneven heat transfer causes the metal foil 10 to be strained and plastically deformed during crystallization, thereby lowering the space factor of the laminate.

[ example 3-1]

A laminate was produced in the same manner as in example 2-1. In example 3-1, the metal foil 10 was heated by the heating apparatus 1B shown in fig. 6C. Specifically, the base 2 was brought close to the supporting member 30 so that the relative movement speed between the base 2 and the supporting member 30 of the heating device 1B shown in fig. 6C was 125 mm/sec, and the metal foil 10 was sandwiched between them. The temperature of the support member 30 was set to room temperature (in the range of 20 to 50 ℃), and a material having a thermal conductivity of 0.2W/mK, which is made of calcium silicate, was used for the support member 30. The appearance of the metal foil 10 obtained by heating was confirmed, and the fill factor of the obtained laminate was calculated in the same manner as in example 2-1. The results are shown in Table 2.

[ examples 3-2]

A laminate was produced in the same manner as in example 3-1. The differences from example 3-1 are: the base 2 was brought close to the supporting member 30 so that the relative movement speed between the base 2 and the supporting member 30 of the heating apparatus 1B shown in fig. 6C was 128 mm/sec, and the metal foil 10 was sandwiched between them. Further, the different points are: the support member 30 is made of a material having a thermal conductivity of 0.4W/mK and made of glass fiber and cement. The appearance of the metal foil 10 obtained by heating was confirmed, and the fill factor of the obtained laminate was calculated in the same manner as in example 2-1. The results are shown in Table 2.

[ examples 3 to 3]

A laminate was produced in the same manner as in example 3-1. The differences from example 3-1 are: the base 2 was brought close to the supporting member 30 so that the relative movement speed between the base 2 and the supporting member 30 of the heating apparatus 1B shown in fig. 6C was 128 mm/sec, and the metal foil 10 was sandwiched between them. Further, the different points are: the support member 30 was made of a rolled steel material for general structural use (JIS standard: SS400) and had a thermal conductivity of 51.6W/mK. The appearance of the metal foil 10 obtained by heating was confirmed. The results are shown in Table 2.

Examples 3-4 to 3-7

A laminate was produced in the same manner as in example 3-3. Examples 3-4 to 3-7 differ from examples 3-3 in that: the base 2 was brought close to the support member 30 so that the relative movement speed between the base 2 and the support member 30 of the heating apparatus 1B shown in fig. 6C was set to 136 mm/sec, 131 mm/sec, 129 mm/sec, and 136 mm/sec, and the metal foil 10 was sandwiched between them. Further, the different points are: the temperature of the support member 30 on which the metal foil 10 is disposed is set to 100 ℃, 200 ℃, 300 ℃, 400 ℃. The appearance of the metal foil 10 obtained by heating was confirmed. The results are shown in Table 2. The space factor of the laminate of examples 3-5 and 3-6 was calculated in the same manner as in example 2-1 and is shown in Table 2.

TABLE 2

As is clear from table 2, when comparing examples 3-1 to 3-3, the metal foil 10 of example 3-1 was free from wrinkles, and the lamination of example 3-1 had a higher lamination factor than that of example 3-2. This is because the thermal conductivity of the support member 30 greatly differs in examples 3-1 to 3-3. It is considered that if the support member 30 made of a material having a low thermal conductivity (0.2W/mK or less) is used as in example 3-1, the heat of the metal foil 10 is less likely to be locally dissipated to the support member 30, the metal foil 10 can be uniformly heated, and plastic deformation is less likely to occur during crystallization of the metal foil 10.

As is clear from table 2, when comparing examples 3-3 to 3-7, the metal foils 10 of examples 3-6 and 3-7 were free from wrinkles, and the lamination of example 3-6 had a higher lamination factor than that of example 3-5. This is because the temperature of the support member 30 greatly differs in examples 3-3 to 3-7. It is considered that if the support member 30 is set to 300 ℃ or higher as in examples 3 to 6 and 3 to 7, the temperature of the support member 30 is set close to the temperature of the base 2, and thus the heat of the metal foil 10 is hardly dissipated locally to the support member 30, and the metal foil 10 can be heated uniformly, and plastic deformation is hardly caused at the time of crystallization of the metal foil 10.

Example 4-1 to example 4-4

A laminate was produced in the same manner as in example 3-1. Examples 4-1 to 4-4 are different from example 3-1 in the following points: the base 2 was brought close to the support member 30 so that the relative movement speeds between the base 2 and the support member 30 of the heating apparatus 1B shown in fig. 6C were 21 mm/sec, 86 mm/sec, 125 mm/sec, and 531 mm/sec in this order, and the metal foil 10 was sandwiched between them. Example 4-3 is the same as example 3-1. The appearance of the metal foil 10 obtained by heating was confirmed. The results are shown in Table 3. Table 3 also shows the space factor of the laminates of examples 4-2 and 4-3.

TABLE 3

As is clear from table 3, when comparing examples 4-1 to 4-4, the metal foils 10 of examples 4-3 and 4-4 were free from wrinkles, and the lamination of example 4-3 had a higher lamination factor than that of example 4-2. This is because the moving speeds of the support member 30 are greatly different in examples 4-1 to 4-4. It is considered that by setting the moving speed to 125 mm/sec or more as in examples 4-3 and 4-4, the metal foil 10 can be instantaneously sandwiched between the base 2 and the support member 30 to uniformly heat the metal foil 10, and plastic deformation is less likely to occur at the time of crystallization of the metal foil 10.

While the embodiments of the present invention have been described in detail, the present invention is not limited to the embodiments described above, and various design changes can be made without departing from the spirit of the present invention described in the claims.

In the present embodiment, the stator core of the motor is produced by laminating the metal foil made of the nanocrystalline soft magnetic material, but the rotor core of the motor may be produced by laminating the metal foil.

In the present embodiment, the installation surface of the base is directed upward, but for example, the installation surface of the base may be directed downward so that the installation surface approaches the metal foil from above the metal foil, and the metal foil may be adsorbed and heated while being transported together with the base.

In the present embodiment, the temperature (heating temperature) of the mounting surface of the base is set to be constant, but the temperature of the mounting surface may be lowered by stopping heating of the heater at the time point when the metal foil self-heats, for example.

Claims

1. A method for manufacturing a metal foil made of a nanocrystalline soft magnetic material, the method comprising:

preparing a metal foil made of an amorphous soft magnetic material; and

a step of crystallizing an amorphous soft magnetic material as the metal foil into the nanocrystalline soft magnetic material by heating the metal foil while bringing the prepared metal foil into close contact with a metal base so as to follow a mounting surface of the metal base,

2. The method of manufacturing a metal foil according to claim 1,

in the crystallization step, the metal foil is heated by a heater built in the base.

3. The method of manufacturing a metal foil according to claim 1 or 2,

in the crystallization step, when the metal foil is brought into close contact with the base, the metal foil is sucked from a suction port formed in the base, thereby bringing the metal foil into close contact with the base.

4. The method for producing a metal foil according to any one of claims 1 to 3,

in the step of preparing the metal foil, the metal foil made of the amorphous soft magnetic material is produced by blowing a molten metal obtained by melting a raw material of the metal foil onto a rotating roll, and cooling and solidifying the molten metal on the roll,

when the metal foil is brought into close contact with the base, a surface of the metal foil on a side in contact with the roller is brought into close contact with the mounting surface.

5. The method for producing a metal foil according to any one of claims 1 to 4,

in the step of preparing a metal foil, a metal foil made of an iron-based amorphous soft magnetic material is prepared as the metal foil,

the crystallization step is a step of placing the metal foil on a support member, moving at least one of a base and the support member in a direction in which the base and the support member are brought into close proximity, sandwiching the metal foil between the base and the support member, thereby bringing the metal foil into close contact with the base, and heating the metal foil by a heater built in the base,

in the crystallization step, the following condition (i) or (ii) is satisfied,

(i) the thermal conductivity of the material constituting the support member is 0.2W/mK or less;

(ii) the temperature of the support member is set to 300 ℃ or higher and less than the crystallization starting temperature.