JP6502015B2 - Method of manufacturing permanent magnet - Google Patents

Description

The present invention relates to a manufacturing method of that permanent magnet to constitute the polar anisotropy ring magnet.

  In recent years, in machine tools, vehicles, aircraft, wind turbines, etc., generators that convert mechanical kinetic energy transmitted from an engine or the like into electrical energy, and conversely, motors that convert electrical energy into mechanical kinetic energy ( A rotating electrical machine such as a motor) is generally used. Further, in recent years, the above-mentioned rotating electrical machine is also required for noise reduction and vibration reduction as well as high efficiency.

  Here, as a permanent magnet used for a rotating electrical machine, there is an anisotropic magnet in which the directions of easy magnetization axes (C-axis) of the magnet particles constituting the permanent magnet are aligned in order to improve the magnetic characteristics. Here, axial anisotropy, radial anisotropy, polar anisotropy, etc. exist as a method of aligning the magnetization easy axis of the anisotropic magnet. Here, in particular, the ring magnet oriented in polar anisotropy disclosed in Japanese Patent Laid-Open No. 2005-44820 has a maximum magnetic flux density higher than that of other anisotropic ring magnets, and has a sinusoidal magnetic flux density distribution. It is possible to get. For example, FIG. 13 is a diagram showing an ideal magnetic flux density distribution of each anisotropic ring magnet of radial anisotropy and polar anisotropy. Therefore, if the polar anisotropic ring magnet is applied to, for example, a magnet for a motor, there is an advantage that the driving force of the motor can be improved, the torque ripple can be limited, and the drive control of the motor can be accurately performed.

JP, 2005-44820, A (pages 6-8)

  Here, the torque ripple is generated because the electromagnetic force generated in the air gap between the rotor of the rotating electrical machine and the stator changes as the rotor rotates, and causes noise and vibration of the rotating electrical machine. As a method of reducing the torque ripple, it is important to smooth the change of the magnetic flux in the air gap so as to reduce the change of the electromagnetic force accompanying the rotation of the rotor. That is, if the magnetic flux density distribution in the circumferential direction of the outer circumferential surface of the polar anisotropic ring magnet used in the rotating electrical machine has an ideal sine wave shape, the change of the magnetic flux in the air gap becomes smooth and torque ripple is reduced. Is possible.

  However, in the prior art, it was very difficult to make the magnetic flux density distribution in the circumferential direction of the outer peripheral surface of the polar anisotropic ring magnet into an ideal sinusoidal shape. Specifically, the shape of the magnetic flux density distribution is distorted as a result of including a harmonic component whose frequency is n times (for example, 5 times, 7 times, 8 times, 10 times) the fundamental wave. Here, FIG. 14 is a view showing the shape of the magnetic flux density distribution in the circumferential direction of the outer peripheral surface of the conventional polar anisotropic ring magnet and the analysis results of harmonics by Fourier analysis. As shown in FIG. 14, the magnetic flux density distribution includes a plurality of harmonics in addition to the fundamental wave having a period of 180 °. Specifically, the third harmonic having a period of 60 °, the fifth harmonic having a period of 36 °, the seventh harmonic having a period of 25.7 °, and the eighth harmonic having a period of 20 ° are included. In addition, the amplitude of the largest fifth harmonic is about 1⁄8 of the amplitude of the fundamental wave, resulting in distortion of the magnetic flux density distribution from the ideal sinusoidal shape. In addition, there is also a problem that harmonic loss (eddy current loss, hysteresis loss) occurs due to the inclusion of harmonic components.

The present invention has been made to solve the above-mentioned problems in the prior art, and by bringing the magnetic flux density distribution in the circumferential direction of the outer peripheral surface of the polar anisotropic ring magnet closer to an ideal shape designed in advance. to reduce harmonic losses, and an object thereof is to provide a method of manufacturing a permanent magnet that achieves noise reduction and lower vibration of the rotary electric machine using the polar-anisotropic ring magnet.

In order to achieve the above object, a method of manufacturing a permanent magnet according to claim 1 of the present invention is a method of manufacturing a polar anisotropic ring magnet, wherein the magnetic flux density distribution in the circumferential direction of the outer peripheral surface is measured or electromagnetic field analysis And the step of designing the orientation direction of the magnetization easy axis based on the measured shape of the magnetic flux density distribution, and in the step of designing the orientation direction, the shape of the measured magnetic flux density distribution The harmonic component is extracted by Fourier analysis, and the fundamental wave and the extracted harmonic component are compared, and the amplitude of the harmonic component is the amplitude of the fundamental wave with respect to the shape of the magnetic flux density distribution in the circumferential direction of the outer peripheral surface. The orientation direction of the magnetization easy axis is feedback-designed so as to be equal to or less than one-tenth of the above, and the magnetization easy axis is oriented in the designed orientation direction.

A method of manufacturing a permanent magnet according to claim 2 is the method of manufacturing a permanent magnet according to claim 1 , wherein in the step of designing the orientation direction, the shape of the fundamental wave of the measured magnetic flux density distribution However, the orientation direction of the magnetization easy axis of the polar anisotropic ring magnet is designed to be closer to a sine wave shape.

A method of manufacturing a permanent magnet according to a third aspect of the present invention is the method of manufacturing the permanent magnet according to the first or second aspect , wherein the step of grinding a magnet raw material into a magnetic powder, and the crushed magnetic powder Forming a mixture in which the mixture is mixed with a binder, forming the mixture into a shaped body having a predetermined shape, orienting the magnetic field with respect to the shaped body, and sintering the shaped body subjected to the magnetic field orientation And sinter by holding, and in the step of orienting the magnetic field, the axis of easy magnetization is oriented in the orientation direction designed in the step of designing the orientation direction.

A method of manufacturing a permanent magnet according to a fourth aspect of the present invention is the method of manufacturing a permanent magnet according to the third aspect , wherein in the step of orienting the magnetic field, a direction of applying a magnetic field to the molded body is controlled. Thereby, the easy axis of magnetization is oriented in the designed orientation direction.

A method of manufacturing a permanent magnet according to a fifth aspect of the present invention is the method of manufacturing a permanent magnet according to the third aspect , wherein in the step of orienting the magnetic field, the magnetic field is applied to the mixture and the magnetic field is applied. The direction of the axis of easy magnetization is manipulated by deforming the mixture into the compact, the magnetic field is oriented with respect to the compact, the direction in which the magnetic field is applied to the mixture, or the deformation mode of the mixture By controlling, the easy axis of magnetization is oriented in the designed orientation direction.

A method of manufacturing a permanent magnet according to a sixth aspect of the present invention is the method of manufacturing the permanent magnet according to the fifth aspect , wherein, in the step of orienting the magnetic field, the sheet is formed after the mixture is formed into a sheet. It is characterized by orientating the magnetic field to the mixture.

According to the method of manufacturing a permanent magnet according to claim 1 having the above configuration, the amplitude of the harmonic component of the magnetic flux density distribution in the circumferential direction of the outer peripheral surface of the manufactured polar anisotropic ring magnet is compared with the amplitude of the fundamental wave. And the magnetic flux density distribution can be made close to a previously designed ideal shape. In addition, when the manufactured permanent magnet is installed in the rotating electrical machine, the change in magnetic flux in the air gap becomes smooth, so it is possible to reduce the torque ripple and realize noise reduction and vibration reduction of the rotating electrical machine. . In addition, harmonic loss (eddy current loss, hysteresis loss) can be reduced.
In addition, since the orientation direction of the magnetization easy axis is designed based on the shape of the measured magnetic flux density distribution, the waveform of the magnetic flux density distribution in the circumferential direction of the outer peripheral surface of the polar anisotropic ring magnet is more intended by the manufacturer. It is possible to approximate the shape to
In addition, since the orientation direction of the magnetization easy axis is feedback-designed based on the measured shape of the magnetic flux density distribution, the orientation design of the permanent magnet can be easily and accurately performed as compared with the prior art. As a result, it becomes possible to manufacture a permanent magnet having an orientation suitable for each rotation motor.

Further, according to the method of manufacturing a permanent magnet according to claim 2 , it is possible to make the waveform of the magnetic flux density distribution in the circumferential direction of the outer peripheral surface of the polar anisotropic ring magnet to be manufactured approach an ideal sine wave shape Become. As a result, torque ripples can be reduced, and drive control of the rotating electrical machine can be accurately performed when installed in the rotating electrical machine.

Further, according to the method of manufacturing a permanent magnet of the third aspect , since a mixture of magnet powder and a binder is formed, the magnet particles rotate after orientation as compared with the case of using powder compacting or the like. It is also possible to improve the degree of orientation. Further, when performing magnetic field orientation on a molded body, the number of turns of current can be used, so that a large magnetic field strength can be secured during magnetic field orientation, and a long time magnetic field application can be performed with a static magnetic field. Therefore, it is possible to realize a high degree of orientation with less variation.

Further, according to the method of manufacturing a permanent magnet according to claim 4 , it is possible to properly orient the magnetization easy axis in the direction intended by the manufacturer by controlling the direction in which the magnetic field is applied to the molded body. It becomes possible.

Further, according to the method of manufacturing a permanent magnet according to the fifth aspect of the present invention, since molding into a molded body is performed while manipulating the direction of the magnetization easy axis by deforming the mixture after orientation, it is easy to magnetize the complex shape. Even in the case of orienting the axis, it is possible to realize high orientation and orientation with less variation. Therefore, even if the orientation design of the permanent magnet is complicated as compared with the prior art, it can be realized accurately.

Furthermore, according to the method of manufacturing a permanent magnet according to the sixth aspect , the mixture of the magnet powder and the binder is made into a sheet-like green sheet, so that subsequent processing such as deformation to a molded body can be performed more easily. It is possible to more easily orient the magnetization easy axis. Also, productivity can be improved.

FIG. 1 is an overall view showing a permanent magnet according to the present invention. It is the figure which showed the rotor of the SPM motor in which the permanent magnet was arrange | positioned. It is the figure which showed the magnetization easy axis direction of the permanent magnet. It is the figure which showed the magnetization easy axis direction of the permanent magnet. FIG. 6 shows polar anisotropic orientation formed by permanent magnets disposed on the surface of the rotor. It is an explanatory view showing a manufacturing process of a permanent magnet concerning the present invention. It is explanatory drawing which showed the formation process of the green sheet especially among the manufacturing processes of the permanent magnet which concerns on this invention. It is the figure which showed the permanent magnet created by laminating | stacking a green sheet, and magnetization easy axis direction. It is a figure explaining the temperature rising aspect of a calcination process especially among the manufacturing processes of the permanent magnet concerning the present invention. It is an explanatory view showing a manufacturing process of a permanent magnet concerning the present invention. It is a figure explaining the measuring method of the magnetic flux density distribution in the perimeter surface of a permanent magnet. It is a figure explaining change of magnetic flux density distribution by feedback design. It is a figure explaining the problem of a prior art. It is a figure explaining the problem of a prior art.

  Hereinafter, an embodiment embodying a permanent magnet and a method of manufacturing the permanent magnet according to the present invention will be described in detail with reference to the drawings.

[Configuration of permanent magnet]
First, the configuration of the permanent magnet 1 according to the present invention will be described. FIG. 1 is an overall view showing a permanent magnet 1 according to the present invention. As shown in FIG. 1, the permanent magnet 1 according to the present invention is a polar anisotropic ring magnet having an annular shape. Then, as shown in FIG. 2, a plurality of the magnets are disposed on the surface of the rotor 2 of the surface magnet type generator (or motor) to constitute the surface magnet type generator (or motor). In the following embodiment, an example in which the permanent magnet 1 is a polar anisotropic ring magnet will be described, but the shape (for example, the size of the diameter) of the permanent magnet 1 and the number of poles etc. It can be appropriately changed depending on the molding mode and the orientation mode.

  Moreover, the permanent magnet 1 which concerns on this invention consists of a Nd-Fe-B type | system | group magnet. The content of each component is Nd: 27 to 40 wt%, B: 0.8 to 2 wt%, and Fe (electrolytic iron): 60 to 70 wt%. In addition, in order to improve the magnetic properties, other elements such as Dy, Tb, Co, Cu, Al, Si, Ga, Nb, V, Pr, Mo, Zr, Ta, Ti, W, Ag, Bi, Zn, Mg, etc. May contain a small amount.

  Further, as shown in FIG. 1, the permanent magnet 1 is formed of a pressure-sensitive adhesive (for example, a mixture of a resin and a solvent) made of a resin or the like after the plurality of fan-shaped (segment type) sintered members 3 are combined in an annular shape. It is configured by being joined and then magnetized. In addition, it is also possible to perform joining of the sintering member 3 by a plasticizer and thermocompression bonding other than an adhesive. Further, the number of sintered members 3 is a number corresponding to the number of poles of permanent magnet 1. For example, when the number of poles of permanent magnet 1 is eight, as shown in FIG. It consists of

  Further, each sintered member 3 constituting the permanent magnet 1 is formed of a green body obtained by molding a mixture of a magnet powder and a binder as described later. The mixture may be once formed into a shape other than the final product shape, and then subjected to punching, cutting, deformation, etc. to form the final product shape. Further, in particular, if the mixture is formed into a sheet shape and then processed into the final product shape, productivity can be improved by producing in a continuous process, and the accuracy of molding can also be improved. When making a mixture into a sheet shape, it is set as the thin film-like sheet member provided with the thickness of 0.05 mm-10 mm (for example, 1 mm), for example. Even in the case of the sheet shape, it is possible to manufacture a large permanent magnet 1 by laminating a plurality of sheets.

  Further, the permanent magnet 1 according to the present invention is an anisotropic magnet, and as shown in FIG. 3, each sintered member 3 constituting the permanent magnet 1 has one direction along the focusing axis P passing through the magnet surface ( In FIG. 3, the magnetization easy axis (C axis) is oriented so as to be focused in the convex direction). As a result, the orientation of the ring-shaped permanent magnet 1 in which the sintered members 3 are combined has polar anisotropy as described later.

  Although the focusing axis P is set to pass near the center of the sintered member 3 in the example shown in FIG. 3, it may be set to the right or left side instead of the center. When the permanent magnet 1 is disposed on the rotor 2, as shown in FIG. 3, the magnetization easy axis (C axis) is on the outer circumferential side from the both ends to the center side along the circumferential direction of the rotor 2. It is oriented to be inclined. More specifically, the easy axis of magnetization is formed along an exponential curve. As a result, when the permanent magnet 1 is disposed on the rotor 2 and magnetized, the magnetic flux inside the magnet is concentrated from the central direction of the rotor 2 to the outer peripheral direction (that is, the magnetic flux density on the magnet surface becomes high). It becomes. Further, in the present invention, in particular, the magnetic flux density distribution in the circumferential direction of the outer peripheral surface of the permanent magnet 1 is measured by measurement or electromagnetic field analysis as described later, based on the shape of the measured magnetic flux density distribution. Design the orientation direction of the magnetization easy axis. Specifically, it is drawn when the shape of the magnetic flux density distribution (specifically, the value of the measured magnetic flux density on the vertical axis, and the angle when the horizontal axis is moved in the circumferential direction about the center of the ring) is drawn In the waveform shape, the orientation direction of the magnetization easy axis of the permanent magnet 1 is designed so as to approach an ideal sine wave shape in which the amplitude of the harmonic component is equal to or less than 1/10 of the amplitude of the fundamental wave.

  Further, as shown in FIG. 4, the magnetization easy axis may be oriented so as to be linearly focused in one direction along the focusing axis P. Even in that case, the orientation of the permanent magnet 1 in which the sintered members 3 are combined has polar anisotropy.

  Further, in the permanent magnet 1 according to the present invention, as described later, since the magnetic field is applied to the mixture in which the mixture of the magnet powder and the binder is mixed to be oriented, the magnet particles are applied by the pressure applied after orientation like compacting. Does not rotate, and it is possible to improve the degree of orientation. In addition, since the density distribution of the magnet powder does not vary as in the PLP method, the near net shape property is improved. Furthermore, after orientation is performed by applying a magnetic field to the mixture before forming into the final product shape (for example, the fan-like shape shown in FIG. 1), the mixture in consideration of the direction of the magnetization easy axis of the mixture Can be shaped (e.g., deformed) and formed into a final product shape, so that the direction of the magnetization easy axis can be manipulated in the process of forming the final product shape. That is, it is possible to properly orient the magnetization easy axis in the direction intended by the manufacturer. As a result, a permanent magnet in which the axis of easy magnetization is oriented in a complicated direction (for example, a polar anisotropic ring magnet oriented so as to focus the axis of easy magnetization in a specific direction as shown in FIG. 3) is easily and accurately realized It is possible to

  In the magnetic field orientation with respect to the permanent magnet 1, as described above, the magnetic field is applied to the mixture before forming into the final product shape (for example, the sector shape shown in FIG. 1) to perform orientation once. Thereafter, molding may be performed to form a magnetic field orientation with respect to the molded body, or after forming into a final product shape, a magnetic field may be applied to perform orientation.

  And, as shown in FIG. 3 and FIG. 4, in particular, the permanent magnet 1 in which the sintered members 3 having the easy magnetization axis oriented are joined in an annular shape can realize polar anisotropic orientation as shown in FIG. It becomes. Thereby, it is possible to obtain a sinusoidal magnetic flux density distribution. Furthermore, the shape of the magnetic flux density distribution in the air gap between the rotor 2 and the stator can also be made sinusoidal. In the present invention, in particular, the magnetic flux density distribution in the circumferential direction of the outer peripheral surface of the permanent magnet 1 is measured by measurement or electromagnetic field analysis, and the orientation direction of the magnetization easy axis of the permanent magnet 1 is determined based on the measured magnetic flux density distribution. Because of the design, it becomes possible to approximate an ideal sine wave shape in which the amplitude of the harmonic component is less than one tenth of the amplitude of the fundamental wave. And, in the rotating electrical machine provided with permanent magnets having polar anisotropic orientation, the torque and the amount of power generation of the rotating electrical machine can be improved, and further, the torque ripple can be limited, and drive control of the rotating electrical machine can be accurately performed. is there. In addition, by making the waveform of the magnetic flux density distribution in the circumferential direction of the outer peripheral surface of the permanent magnet 1 (that is, the magnetic flux density distribution in the air gap of the rotating electrical machine) approach an ideal sine wave shape, torque ripple is further reduced, It becomes possible to realize noise reduction and vibration reduction of the electric machine.

（但し、Ｒ１及びＲ２は、水素原子、低級アルキル基、フェニル基又はビニル基を表す） Further, in the present invention, particularly when manufacturing the permanent magnet 1, as the binder mixed with the magnet powder, a resin, a long chain hydrocarbon, a fatty acid ester, a mixture thereof or the like is used.
Furthermore, when using a resin as a binder, it is preferable to use a polymer which does not contain an oxygen atom in the structure and which is depolymerizable. In addition, a thermoplastic resin is used in order to reuse the remainder of the mixture produced when forming the mixture of the magnet powder and the binder into a desired shape (for example, a fan-shaped shape) as described later. Specifically, a polymer consisting of one or more polymers or copolymers selected from monomers represented by the following general formula (1) corresponds.

(However, R1 and R2 represent a hydrogen atom, a lower alkyl group, a phenyl group or a vinyl group)

Examples of the polymer corresponding to the above conditions include polyisobutylene (PIB), which is a polymer of isobutylene, polyisoprene (isoprene rubber, IR), which is a polymer of isoprene, and polybutadiene (butadiene, which is a polymer of 1,3-butadiene. Rubber, BR), polystyrene, which is a polymer of styrene, styrene-isoprene block copolymer (SIS), which is a copolymer of styrene and isoprene, butyl rubber (IIR), which is a copolymer of isobutylene and isoprene, styrene and butadiene Styrene-butadiene block copolymer (SBS), which is a copolymer of the above, 2-methyl-1-pentene polymerization resin which is a polymer of 2-methyl-1-pentene, and a polymer of 2-methyl-1-butene Certain 2-methyl-1-butene polymers, polymers of α-methylstyrene That there is α- methyl styrene polymer resin. Incidentally, it is desirable to add low molecular weight polyisobutylene in order to give flexibility to the α-methylstyrene polymer resin. The resin used for the binder may contain a small amount of a polymer or copolymer (for example, polybutyl methacrylate or polymethyl methacrylate) of a monomer containing an oxygen atom. Furthermore, monomers not corresponding to the above general formula (1) may be partially copolymerized. Even in that case, it is possible to achieve the object of the present invention.
As the resin used for the binder, it is desirable to use a thermoplastic resin that softens at 250 ° C. or less, more specifically, a thermoplastic resin having a glass transition point or melting point of 250 ° C. or less, in order to properly perform magnetic field alignment. .

  On the other hand, when using a long chain hydrocarbon as a binder, it is preferable to use a long chain saturated hydrocarbon (long chain alkane) which is solid at room temperature and liquid at room temperature or more. Specifically, it is preferable to use a long chain saturated hydrocarbon having 18 or more carbon atoms. And when carrying out the magnetic field orientation of the mixture of a magnet powder and a binder as mentioned later, a magnetic field orientation is performed in the state which heated and softened the mixture above the glass transition point or melting point of long chain hydrocarbon.

  Similarly, in the case of using a fatty acid ester as the binder, it is preferable to use methyl stearate, methyl docosanoate, etc. which are solid at room temperature and liquid above room temperature. And when carrying out the magnetic field orientation of the mixture of a magnet powder and a binder as mentioned later, a magnetic field orientation is performed in the state which heated the mixture above the melting point of fatty acid ester, and was softened.

  By using a binder that satisfies the above conditions as the binder to be mixed with the magnet powder, it is possible to reduce the amount of carbon and the amount of oxygen contained in the magnet. Specifically, the amount of carbon remaining in the magnet after sintering is set to 2000 ppm or less, more preferably 1000 ppm or less. Further, the amount of oxygen remaining in the magnet after sintering is set to 5000 ppm or less, more preferably 2000 ppm or less.

  In addition, the amount of the binder added is such that the gaps between the magnet particles are appropriately filled in order to improve the thickness accuracy of the formed body when forming the slurry or the heated and melted compound. For example, the ratio of the binder to the total amount of the magnetic powder and the binder is 1 wt% to 40 wt%, more preferably 2 wt% to 30 wt%, and still more preferably 3 wt% to 20 wt%.

[Method 1 of manufacturing permanent magnet]
Next, a first method of manufacturing the permanent magnet 1 according to the present invention will be described with reference to FIG. FIG. 6 is an explanatory view showing a manufacturing process of the permanent magnet 1 according to the present embodiment.

  First, an ingot made of Nd-Fe-B of a predetermined fraction (for example, Nd: 32.7 wt%, Fe (electrolytic iron): 65.96 wt%, B: 1.34 wt%) is manufactured. Thereafter, the ingot is roughly crushed to a size of about 200 μm by a stamp mill, a crusher or the like. Alternatively, the ingot is melted, flakes are produced by a strip casting method, and roughly pulverized by a hydrogen disintegration method. Thereby, coarsely crushed magnet powder 10 is obtained.

  Next, the coarsely pulverized magnet powder 10 is pulverized by a wet method using a bead mill 11 or a dry method using a jet mill. For example, in pulverization using a wet method with a bead mill 11, the coarsely pulverized magnet powder 10 is finely pulverized in a solvent to a particle size in a predetermined range (for example, 0.1 μm to 5.0 μm) and the magnet powder is dispersed in the solvent . Thereafter, the magnet powder contained in the solvent after wet pulverization is dried by vacuum drying or the like, and the dried magnet powder is taken out. Further, the type of solvent used for the pulverization is not particularly limited, and alcohols such as isopropyl alcohol, ethanol and methanol, esters such as ethyl acetate, lower hydrocarbons such as pentane and hexane, aromatics such as benzene, toluene and xylene And ketones and mixtures thereof can be used. Preferably, a solvent containing no oxygen atom is used.

  On the other hand, in pulverization using a dry method using a jet mill, the roughly pulverized magnet powder is (a) in an atmosphere comprising an inert gas such as nitrogen gas, Ar gas, He gas, etc., which has an oxygen content of substantially 0%. Or (b) finely divided by a jet mill in an atmosphere consisting of an inert gas such as nitrogen gas, argon gas, helium gas, etc. with an oxygen content of 0.0001 to 0.5%, and a particle size within a predetermined range (for example, It is set as a fine powder which has an average particle diameter of 0.7 micrometer-5.0 micrometers. The oxygen concentration is substantially 0%, which is not limited to the case where the oxygen concentration is completely 0%, and even if it contains an amount of oxygen that forms a slight oxide film on the surface of the fine powder. It means good things.

  Next, the magnet powder finely pulverized by bead mill 11 grade | etc., Is shape | molded in a desired shape. The formation of the magnetic powder is performed by forming a mixture of the magnetic powder and the binder. In the following embodiments, the magnetic material is applied to perform magnetic field orientation in a state where the mixture is once molded into a shape other than the final product shape, and then punching, cutting, deformation processing and the like are performed to obtain the final product shape (for example, FIG. Fan-shaped shown in). In particular, in the following examples, the mixture is formed into a sheet shape (hereinafter referred to as a green sheet) and then formed into a final product shape. When the mixture is formed into a sheet, in particular, hot melt coating in which a compound obtained by mixing a magnet powder and a binder is heated and then formed into a sheet and a slurry containing the magnet powder, a binder and an organic solvent There is molding by slurry coating or the like which is molded into a sheet shape by coating on a substrate.

Below, the green sheet formation which used especially hot-melt coating is demonstrated.
First, a binder is mixed with the magnet powder finely pulverized by a bead mill 11 or the like to prepare a powdery mixture (compound) 12 composed of the magnet powder and the binder. Here, as the binder, as described above, a resin, a long chain hydrocarbon, a fatty acid ester, a mixture thereof or the like is used. For example, when a resin is used, a thermoplastic resin containing no oxygen atom in the structure and consisting of a depolymerizable polymer is used, while when using a long chain hydrocarbon, it is solid at room temperature, not less than room temperature It is preferred to use a long chain saturated hydrocarbon (long chain alkane) which is a liquid. Moreover, when using fatty acid ester, it is preferable to use methyl stearate, methyl docosanoate, or the like. The amount of binder added is 1 wt% to 40 wt%, more preferably 2 wt% to 30 wt%, and still more preferably 3 wt% of the binder relative to the total amount of magnet powder and binder in compound 12 after addition as described above. The amount is from 20% to 20%.

  Further, an additive for promoting orientation may be added to the compound 12 in order to improve the degree of orientation in the magnetic field orientation step to be performed later. As an additive for promoting orientation, for example, a hydrocarbon-based additive is used, and in particular, it is desirable to use a polar additive (specifically, an acid dissociation constant pKa of less than 41). Further, the addition amount of the additive depends on the particle size of the magnetic powder, and the smaller the particle size of the magnetic powder, the more the addition amount needs to be. The specific addition amount is 0.1 part to 10 parts, more preferably 1 part to 8 parts with respect to the magnetic powder. Then, the additive added to the magnet powder adheres to the surface of the magnet particles, and has a function of assisting the rotation of the magnet particles in the magnetic field orientation processing described later. As a result, when a magnetic field is applied, orientation is easily performed, and it becomes possible to align the magnetization easy axis directions of the magnet particles in the same direction (that is, to increase the degree of orientation). In particular, when a binder is added to the magnetic powder, since the binder is present on the surface of the particles, the frictional force at the time of orientation is increased, and the orientation of the particles is reduced.

  The addition of the binder is performed in an atmosphere of an inert gas such as nitrogen gas, Ar gas, or He gas. The mixing of the magnet powder and the binder is performed, for example, by charging the magnet powder and the binder into a stirrer and stirring the mixture with the stirrer. Also, heating and stirring may be performed to promote the kneadability. Moreover, it is desirable that the mixing of the magnet powder and the binder be performed in an atmosphere of an inert gas such as nitrogen gas, Ar gas, or He gas. Further, particularly when the magnet powder is ground by a wet method, the binder is added to the organic solvent and kneaded without removing the magnet powder from the organic solvent used for grinding, and thereafter the organic solvent is volatilized, as described later Alternatively, the compound 12 may be obtained.

  Subsequently, the compound 12 is formed into a sheet to form a green sheet. In particular, in the case of hot melt coating, the compound 12 is melted by heating the compound 12 to be in a fluid state, and then coated on a support base 13 such as a separator. Thereafter, the long sheet-like green sheet 14 is formed on the support base 13 by radiating and solidifying. In addition, although the temperature at the time of heat-melting the compound 12 changes with kinds and quantity of the binder to be used, it shall be 50-300 degreeC. However, the temperature needs to be higher than the melting point of the binder used. When slurry coating is used, the magnetic powder and the binder are dispersed in a large amount of organic solvent, and the slurry is coated on the support base 13 such as a separator. Thereafter, the green sheet 14 in the form of a long sheet is formed on the support base 13 by drying and volatilizing the organic solvent.

  Here, as a coating method of the melted compound 12, it is preferable to use a method excellent in layer thickness controllability such as a slot die method or a calendar roll method. In particular, in order to realize high thickness accuracy, a die method or comma coating method which is particularly excellent in layer thickness controllability (that is, a method capable of applying a layer of high accuracy thickness on the surface of a substrate) It is desirable to use For example, in the slot die method, coating is performed by extruding the heated and fluid compound 12 with a gear pump and inserting it into a die. In the calendar roll system, a fixed amount of the compound 12 is charged in the gap of the heated two rolls, and the compound 12 melted by the heat of the roll is coated on the support base 13 while rotating the roll. In addition, as the support base 13, for example, a silicone-treated polyester film is used. Furthermore, it is preferable to carry out the defoaming treatment sufficiently so that air bubbles do not remain in the spreading layer by using an antifoaming agent or performing heating vacuum degassing. Also, the green sheet on the support base 13 is formed by molding the compound 12 melted by extrusion molding or injection molding into a sheet and extruding the same onto the support base 13 instead of coating the support base 13. The structure 14 may be molded.

  In the step of forming the green sheet 14 by the slot die method, the sheet thickness of the green sheet 14 after coating is measured, and the gap D between the die 15 and the support base 13 is feedback controlled based on the measured value. desirable. Also, the fluctuation of the amount of the fluid compound 12 supplied to the die 15 is reduced as much as possible (for example, suppressed to ± 0.1% or less), and the fluctuation of the coating speed is also reduced as much (for example, ± 0. It is desirable to suppress the fluctuation to 1% or less). Thereby, it is possible to further improve the thickness accuracy of the green sheet 14. The thickness accuracy of the formed green sheet 14 is within ± 10%, more preferably within ± 3%, and still more preferably within ± 1% of the design value (for example, 1 mm). In the other calender roll system, it is possible to control the transferred film thickness of the compound 12 onto the support base 13 by similarly controlling the calender conditions based on the measured values.

  The set thickness of the green sheet 14 is desirably set in the range of 0.05 mm to 20 mm. When the thickness is smaller than 0.05 mm, productivity must be reduced because multilayer lamination must be performed.

  Next, the magnetic orientation of the green sheet 14 formed on the support base 13 by the above-described hot melt coating is performed. Specifically, the green sheet 14 is softened by heating the green sheet 14 which is continuously conveyed together with the support base 13. Specifically, the green sheet 14 is softened until it has a viscosity of 1 to 1500 Pa · s, more preferably 1 to 500 Pa · s. Thereby, magnetic field orientation can be properly performed.

  In addition, although the temperature and time at the time of heating the green sheet 14 change with kinds and quantity of the binder to be used, they are 100-250 degreeC, for example, and shall be 0.1 to 60 minutes. However, in order to soften the green sheet 14, the temperature needs to be a temperature higher than the glass transition point or the melting point of the binder used. Further, as a heating method for heating the green sheet 14, there are, for example, a heating method using a hot plate and a heating method using a heat medium (silicone oil) as a heat source. Next, magnetic field orientation is performed by applying a magnetic field in the in-plane direction and the length direction of the green sheet 14 softened by heating. The strength of the magnetic field to be applied is 5000 [Oe] to 150000 [Oe], preferably 10000 [Oe] to 120000 [Oe]. As a result, the C axis (magnetic easy axis) of the magnet crystal contained in the green sheet 14 is oriented in one direction. The magnetic field may be applied in the in-plane direction and in the width direction of the green sheet 14 as the direction in which the magnetic field is applied. Alternatively, the magnetic field may be simultaneously oriented to a plurality of green sheets 14.

  Furthermore, when applying a magnetic field to the green sheet 14, the magnetic field may be applied simultaneously with the heating step. Alternatively, the magnetic field may be applied after the heating step and before the green sheet solidifies. It is also possible to carry out the following steps. In addition, it may be configured to be magnetically oriented before the green sheet 14 coated by hot melt coating is solidified. In that case, the heating step is unnecessary.

  Next, the heating process and the magnetic field alignment process of the green sheet 14 will be described in more detail with reference to FIG. FIG. 7 is a schematic view showing the heating process and the magnetic field alignment process of the green sheet 14. In the example shown in FIG. 7, an example in which the magnetic field orientation process is performed simultaneously with the heating process will be described.

  As shown in FIG. 7, heating and magnetic field orientation for the green sheet 14 coated by the above-described slot die method are performed on the long sheet-like green sheet 14 in a state of being continuously transported by a roll. That is, an apparatus for performing heating and magnetic field alignment is disposed on the downstream side of a coating apparatus (such as a die), and is performed by a process continuous with the coating process described above.

Specifically, on the downstream side of the die 15 and the coating roll 22, the solenoid 25 is disposed so that the supported base material 13 and the green sheet 14 to be conveyed pass through the inside of the solenoid 25. Further, the hot plates 26 are disposed in a pair at the upper and lower sides with respect to the green sheet 14 in the solenoid 25. Then, the green sheet 14 is heated by the hot plate 26 arranged in a pair at the top and bottom, and an electric current is supplied to the solenoid 25 so that the in-plane direction of the long sheet-like green sheet 14 (ie, the sheet surface of the green sheet 14 (In a direction parallel to) and in the longitudinal direction. Thereby, the green sheet 14 continuously conveyed is softened by heating, and a magnetic field is applied to the softened green sheet 14 in the in-plane direction and in the length direction (the direction of the arrow 27 in FIG. 8). On the other hand, it is possible to orient the magnetic field appropriately uniform. In particular, by setting the direction in which the magnetic field is applied as the in-plane direction, it is possible to prevent the surface of the green sheet 14 from standing up.
Moreover, it is preferable to perform thermal radiation and solidification of the green sheet 14 performed after carrying out magnetic field orientation in a conveyance state. This makes it possible to make the manufacturing process more efficient.

  When magnetic field orientation is performed in the in-plane direction and width direction of the green sheet 14, a pair of magnetic field coils are disposed on the left and right of the green sheet 14 conveyed instead of the solenoid 25. Then, by supplying current to each magnetic field coil, it becomes possible to generate a magnetic field in the in-plane direction and in the width direction of the long sheet-like green sheet 14.

  It is also possible to make the magnetic field orientation perpendicular to the plane of the green sheet 14. When the magnetic field orientation is performed in the direction perpendicular to the surface of the green sheet 14, for example, a magnetic field application device using a pole piece or the like is used. When the magnetic field orientation direction is perpendicular to the surface of the green sheet 14, it is preferable to laminate a film also on the surface of the green sheet 14 opposite to the surface on which the support base 13 is laminated. Thereby, it is possible to prevent the surface of the green sheet 14 from standing on the surface.

  Further, instead of the heating method by the hot plate 26 described above, a heating method using a heat medium (silicone oil) as a heat source may be used.

  Here, when the green sheet 14 is formed of a highly fluid liquid such as slurry by a general slot die method or a doctor blade method without using hot melt molding, a gradient of a magnetic field is generated. When the green sheet 14 is carried in, the magnetic powder contained in the green sheet 14 is drawn to the side where the magnetic field is strong, and the liquid shift of the slurry forming the green sheet 14, that is, the deviation of the thickness of the green sheet 14 There is a possibility that it will occur. On the other hand, when the compound 12 is formed into the green sheet 14 by hot melt molding as in the present invention, the viscosity in the vicinity of room temperature reaches several tens of thousands to several hundreds of thousands Pa · s and There is no powder shift. Furthermore, by being transported in a uniform magnetic field and heated, the viscosity of the binder is reduced, and uniform C-axis alignment is possible only with rotational torque in the uniform magnetic field.

  When the green sheet 14 is formed of a highly fluid liquid such as a slurry containing an organic solvent by a general slot die method or a doctor blade method without using hot melt molding, the thickness exceeds 1 mm. When it is going to make a sheet | seat, the foaming by the organic solvent contained in a slurry etc. vaporizing at the time of drying becomes a subject. Furthermore, if the drying time is increased to suppress foaming, sedimentation of the magnet powder occurs, which causes deviation in the density distribution of the magnet powder with respect to the direction of gravity, which causes warpage after firing. Therefore, in molding from a slurry, since the upper limit of thickness is substantially regulated, it is necessary to mold a green sheet with a thickness of 1 mm or less and then laminate it. However, in such a case, the entanglement between the binders becomes poor, and delamination occurs in the subsequent binder removal step (pre-sintering treatment), which results in a decrease in C-axis (easy magnetization axis) orientation, ie residual magnetic flux density ( Br) is a cause of decline. On the other hand, when the compound 12 is formed into the green sheet 14 by hot melt molding as in the present invention, since the organic solvent is not contained, even when a sheet having a thickness of more than 1 mm is formed, Concern disappears. And, since the binder is in a sufficiently entangled state, there is no possibility that delamination occurs in the binder removal step.

  When a magnetic field is simultaneously applied to a plurality of green sheets 14, for example, the plurality of green sheets 14 (for example, six sheets) are continuously transported in a stacked state, and the stacked green sheets 14 Configure to pass. This makes it possible to improve productivity.

Then, after magnetic field orientation of the green sheet 14 is performed by the method shown in FIG. 7, a load is applied to the green sheet 14 to deform the green sheet 14 and form it into a final product shape. The above-mentioned deformation displaces the direction of the easy magnetization axis so as to be in the direction of the easy magnetization axis required for the final product. This makes it possible to manipulate the direction of the easy axis so that the easy axis converges in the direction along the focusing axis P as shown in FIG. The green sheet 14 is shaped in consideration of the final product shape and the direction of the easy axis of magnetization required for the final product (i.e., the magnetization required of the final product when it is shaped by the deformation). In advance, it is punched into a shape that can realize the direction of the easy axis, and then deformed.
Further, in the case of manufacturing a large-sized magnet, it may be formed by laminating a plurality of green sheets 14 deformed into the same shape and fixing them together with a resin or the like. For example, in the case of manufacturing the permanent magnet 1 in which the easy magnetization axis (C axis) is oriented such that the easy magnetization axis (C axis) is focused in one direction along the focusing axis P as shown in FIG. The green sheet 14 oriented in the magnetic field is curved and laminated such that the cross section in the thickness direction has an arc shape. As a result, it becomes possible to realize the orientation as shown in FIG. The green sheets 14 may be laminated after being deformed, or may be deformed after being laminated.

Moreover, you may perform magnetic field orientation and shaping | molding to a molded object with the following method.
First, the sheet-like green sheet 14 before magnetic field orientation cut into a suitable length is wound around the mold having a cylindrical shape. Then, a magnetic field is applied to the green sheet 14 wound around the mold from one direction opposite to the surface of the green sheet 14. As a result, the magnetization easy axes of the magnet particles contained in the green sheet 14 are oriented in parallel along the application direction of the magnetic field. Thereafter, a load is applied to the green sheet 14 to deform it into a final product shape, and the direction of the magnetization easy axis so that the magnetization easy axis converges in one direction along the focusing axis P by the deformation. Correct the For example, when making a fan-shaped shape as shown in FIG. 3 into the final product shape, while making the green sheet 14 in a curved state along the mold linear, load from the left and right in the width direction It has a fan shape. As a result, along with the deformation of the green sheet 14, the direction of the magnetization easy axis of the green sheet 14 is also corrected, and the orientation as shown in FIG. 3 can be realized. Only one green sheet 14 may be deformed, or a plurality of green sheets 14 may be deformed in a stacked state.
Further, the shape of the green sheet 14 before being deformed by applying a load may be a shape other than a cylindrical shape. For example, it may have a bow shape, a fan shape, or a rectangular shape. Furthermore, after the green sheet 14 magnetically oriented in the in-plane direction by the method shown in FIG. 9 is punched into an arched shape etc., a load is applied to the punched green sheet 14 to deform it into a final product shape. You may.

  Alternatively, after forming a molded body corresponding to the final product shape, a magnetic field may be applied to the molded body to perform magnetic field orientation. For example, one opening of the solenoid coil is disposed adjacent to and adjacent to the molded body, and a magnetic field formed by applying a current to the solenoid coil is applied to the molded body. In the vicinity of the opening of the solenoid coil, a magnetic field in which magnetic lines of force are diffused in the left and right direction is formed. Accordingly, the shaped body is oriented such that the easy axis (C axis) is focused in one direction along the focusing axis P as shown in FIG. Further, instead of the solenoid coil, permanent magnet or electromagnet may be used for orientation. Furthermore, after forming the mixture into a ring shape, a magnetic field may be applied to the molded body to perform magnetic field orientation.

  Further, in the present invention, in particular, the magnetic flux density distribution in the circumferential direction of the outer peripheral surface of the permanent magnet 1 created as described later is measured by measurement or electromagnetic field analysis, and the permanent magnet is measured based on the measured magnetic flux density distribution. Design the orientation direction of the easy axis of magnetization of 1. Specifically, for the shape of the magnetic flux density distribution, the orientation direction of the magnetization easy axis of the permanent magnet 1 is set so that it approaches an ideal sine wave shape in which the amplitude of the harmonic component is less than 1/10 of the amplitude of the fundamental wave. Configure to design. Then, to control the direction in which the magnetic field is applied to the mixture of the magnet powder and the binder (for example, the green sheet 14) or the molded body, so as to orient the magnetization easy axis in the designed orientation direction or Control of the deformation mode in the process of deforming the subsequent mixture (for example, green sheet 14) into a molded body ", or a combination of both. As a result, even if the orientation design of the permanent magnet is complicated, it is possible to properly orient the easy magnetization axis in the designed direction.

  Subsequently, a non-oxidizing atmosphere (in particular, hydrogen according to the present invention) in which the compacted and magnetically oriented compacted body 30 is pressurized to atmospheric pressure or a pressure higher or lower than atmospheric pressure (for example, 1.0 Pa or 1.0 MPa) The calcination treatment is performed by maintaining the binder decomposition temperature for several hours to several tens of hours (for example, 5 hours) in an atmosphere or a mixed gas atmosphere of hydrogen and an inert gas. In the case of the hydrogen atmosphere, for example, the amount of hydrogen supplied during calcination is 5 L / min. By performing the calcination treatment, it becomes possible to decompose the organic compound such as a binder or the like into a monomer by a depolymerization reaction or the like and scatter and remove it. That is, so-called decarbonization to reduce the amount of carbon in the molded body 30 is performed. Further, the calcination treatment is performed under the condition that the amount of carbon in the molded body 30 is 2000 ppm or less, more preferably 1000 ppm or less. As a result, the entire compact 30 can be densely sintered in the subsequent sintering process, and the residual magnetic flux density and the coercivity do not decrease. Moreover, when performing the pressurization conditions at the time of performing the calcination process mentioned above by pressure higher than atmospheric pressure, it is desirable to set it as 15 Mpa or less. When the pressure is higher than the atmospheric pressure, more specifically, 0.2 MPa or more, the effect of reducing the amount of carbon can be expected particularly.

  The binder decomposition temperature is determined based on the analysis results of the binder decomposition product and decomposition residue. Specifically, a temperature range is selected in which decomposition products of the binder are collected, decomposition products other than the monomer are not generated, and products by side reaction of the remaining binder component are not detected even in the analysis of the residue. Although it changes with kinds of binders, it is 200 ° C-900 ° C, and more preferably 400 ° C-600 ° C (for example, 450 ° C).

  Moreover, it is preferable to make temperature rising rate small compared with the case where sintering of a general magnet is performed in the said calcination process. Specifically, the temperature rising rate is set to 2 ° C./min or less (eg, 1.5 ° C./min). Therefore, when performing the calcination process, as shown in FIG. 9, the temperature is raised at a predetermined temperature rising rate of 2 ° C./min or less, and after reaching a preset set temperature (binder decomposition temperature), A calcination process is performed by holding at the set temperature for several hours to several tens of hours. As described above, by reducing the temperature rising rate in the calcination process, carbon in the molded body 30 is not rapidly removed but is removed stepwise, thereby increasing the density of the permanent magnet after sintering ( That is, it is possible to reduce the air gap in the permanent magnet. If the temperature rise rate is 2 ° C./min or less, the density of the permanent magnet after sintering can be 95% or more, and high magnetic properties can be expected.

Alternatively, the dehydrogenation treatment may be performed by subsequently holding the formed body 30 calcined by the calcination treatment in a vacuum atmosphere. Dehydrogenation process, a calcination process NdH 3 in the compact 30 produced by _(activity Univ), NdH 3 _(activity Univ) → NdH 2 by gradually changed to _(activity small) The activity of the compact 30 activated by the calcination process is reduced. Thereby, even when the molded body 30 calcined by the calcination treatment is subsequently moved to the atmosphere, the coupling of Nd with oxygen is prevented, and the residual magnetic flux density and the coercive force are reduced. There is no In addition, the effect of returning the structure of the magnet crystal from NdH ₂ or the like to the Nd ₂ Fe ₁₄ B structure can also be expected.

Subsequently, a sintering process is performed to sinter the green body 30 calcined by the calcination process. In addition, as a sintering method of the molded body 30, it is possible to use pressure sintering etc. which sinter in the state which pressurized the molded body 30 other than general vacuum sintering. For example, when sintering is performed by vacuum sintering, the temperature is raised to a baking temperature of about 800 ° C. to about 1080 ° C. at a predetermined temperature rising rate, and held for about 0.1 to 2 hours. During this time, vacuum firing is performed, but the degree of vacuum is preferably 5 Pa or less, and more preferably 10 ⁻² Pa or less. After cooling, heat treatment is performed again at 300 ° C. to 1000 ° C. for 2 hours. And the sintered compact 31 is manufactured as a result of sintering.

  Thereafter, as shown in FIG. 10, a plurality of sintered bodies 31 manufactured by the above method are joined in an annular shape. In addition, joining of the sintered compact 31 is performed by an adhesive, a plasticizer, and thermocompression bonding.

  Thereafter, magnetization is performed along the C axis so as to be polar anisotropy. As a result, it becomes possible to manufacture the permanent magnet 1 which is a polar anisotropic ring magnet. For the magnetization of the permanent magnet 1, for example, a magnetizing coil, a magnetizing yoke, a capacitor type magnetizing power supply, etc. are used. The permanent magnet 1 may be magnetized after being disposed on the rotor 2 of the rotating electrical machine.

  Next, the magnetic flux density distribution in the circumferential direction of the outer peripheral surface of the manufactured permanent magnet 1 is measured. The measurement of the magnetic flux density distribution is performed by moving the measurement point O on the outer peripheral surface of the permanent magnet 1 along the circumferential direction as shown in FIG. Measure the The measurement may be performed by fixing the measurement point O and rotating the permanent magnet 1. In addition, the position of the measurement point O may be set not at a position in contact with the surface but at a position separated to some extent from the surface. The shape of the measured magnetic flux density distribution (specifically, the value of the measured magnetic flux density on the vertical axis, and the angle when the horizontal axis is moved in the circumferential direction about the center of the ring) is drawn Based on the waveform shape, the orientation direction of the magnetization easy axis of the permanent magnet 1 is feedback-designed. Specifically, for the shape of the magnetic flux density distribution, the orientation direction of the magnetization easy axis of the permanent magnet 1 is set so that it approaches an ideal sine wave shape in which the amplitude of the harmonic component is less than 1/10 of the amplitude of the fundamental wave. Configure to design with feedback. Here, if the shape of the fundamental wave is a sine wave shape and the amplitude of the harmonic component is sufficiently smaller than that of the fundamental wave (for example, 1/10 or less), the fundamental wave and the harmonic wave are combined. The shape of the magnetic flux density distribution thus obtained approaches an ideal sine wave shape. The measurement of the harmonic component is performed by extracting the harmonic component by Fourier analysis. Then, by comparing the amplitude of the fundamental wave with the amplitude of the harmonic component, it is determined how the amplitude of the harmonic component changes with respect to the amplitude of the fundamental wave.

  In the above feedback design, for example, “a direction in which a magnetic field is applied to a mixture of a magnetic powder and a binder or a formed body” or “a deformation mode from a mixture after orientation to a formed body (specifically, By changing the load application direction and the punching condition of the green sheet 14 before deformation, the orientation direction of the magnetization easy axis of the permanent magnet 1 is changed variously, and the magnetic flux density distribution on the outer peripheral surface is measured. . Then, regarding the shape of the magnetic flux density distribution on the outer peripheral surface, the amplitude of the harmonic component becomes smaller than the amplitude of the fundamental wave, and the orientation direction of the magnetization easy axis approaching the ideal sine wave shape is explored.

  As a result, by repeatedly performing feedback design, the magnetic flux density distribution in the circumferential direction of the outer circumferential surface of the created permanent magnet 1 can be gradually made closer to an ideal sine wave shape as shown in FIG. . In addition, the amplitude of the harmonic component can be gradually reduced with respect to the amplitude of the fundamental wave, and finally can be reduced to 1/10 or less. That is, optimal orientation design of the permanent magnet 1 becomes possible. FIG. 12 is each magnetic flux density distribution measured in the process of feedback design in the case of using the value of the measured magnetic flux density along the vertical axis and the angle when the horizontal axis is moved circumferentially about the center of the ring. It is the figure which showed the analysis result of the harmonic which analyzed the shape of, and the shape of magnetic flux density distribution by Fourier analysis.

[Method 2 of manufacturing permanent magnet]
Next, a second method of manufacturing the permanent magnet 1 according to the present invention will be described.

  Here, in the second manufacturing method, a permanent magnet is manufactured by basically the same process as the above-described first manufacturing method (FIGS. 6 to 12). However, when measuring the magnetic flux density distribution in the circumferential direction of the outer peripheral surface of the permanent magnet in order to perform the orientation design of the magnetization easy axis, the first manufacturing method actually measures the magnetic flux density distribution in the permanent magnet created In contrast to measurement, the second manufacturing method differs in that the magnetic flux density distribution is measured (simulated) by electromagnetic field analysis using Maxwell's equations.

  More specifically, in the second manufacturing method, the magnetic flux density distribution in the circumferential direction of the outer circumferential surface of a virtual permanent magnet having various orientation directions is measured by electromagnetic field analysis. Then, based on the shape of the measured magnetic flux density distribution, the orientation direction of the magnetization easy axis of the permanent magnet is feedback-designed. Specifically, as shown in FIG. 12, the amplitude of the harmonic component in the shape of the magnetic flux density distribution becomes an ideal sine wave shape whose amplitude is less than one tenth of the amplitude of the fundamental wave by repeating the feedback design, as shown in FIG. The orientation direction of the magnetization easy axis of the permanent magnet to be closest is identified.

  The permanent magnet is then manufactured to orient the easy axis of magnetization in the designed orientation direction. The manufacturing process of the permanent magnet 1 is the same as the first manufacturing method (FIG. 6). At that time, "the control of the direction of applying the magnetic field to the mixture of magnet powder and binder (for example, green sheet 14) or the molded body" or "the mixture after orientation (for example, green sheet 14) is deformed and molded Control of deformation in the process of forming into a body "or a combination of both. As a result, even if the orientation design of the permanent magnet is complicated, it is possible to properly orient the easy magnetization axis in the designed direction.

[Method 3 of manufacturing permanent magnet]
Next, a third method of manufacturing the permanent magnet 1 according to the present invention will be described.

  Here, in the third manufacturing method, a permanent magnet is manufactured by basically the same process as the above-described second manufacturing method. However, while the second manufacturing method feedback-designs the orientation direction of the magnetization easy axis, the third manufacturing method designs the orientation direction of the magnetization easy axis by electromagnetic field analysis without using the feedback design. It differs in the point.

  More specifically, in the third manufacturing method, the orientation direction of the magnetization easy axis in which the magnetic flux density distribution in the circumferential direction of the outer circumferential surface of the permanent magnet has a sine wave shape is specified (reverse calculation) by electromagnetic field analysis. As a result, the orientation direction of the permanent magnet specified is an ideal sine wave in which the amplitude of the harmonic component is 1/10 or less of the amplitude of the fundamental wave with respect to the shape of the magnetic flux density distribution in the circumferential direction of the outer peripheral surface of the permanent magnet The orientation direction is designed to approach the shape.

  The permanent magnet is then manufactured to orient the easy axis of magnetization in the designed orientation direction. The manufacturing process of the permanent magnet 1 is the same as the first manufacturing method (FIG. 6). At that time, "the control of the direction of applying the magnetic field to the mixture of magnet powder and binder (for example, green sheet 14) or the molded body" or "the mixture after orientation (for example, green sheet 14) is deformed and molded Control of deformation in the process of forming into a body "or a combination of both. As a result, even if the orientation design of the permanent magnet is complicated, it is possible to properly orient the easy magnetization axis in the designed direction.

As described above, in the method of manufacturing the permanent magnet 1 and the permanent magnet 1 according to the present embodiment, the magnet raw material is pulverized into magnet powder, and the compound 12 is formed by mixing the pulverized magnet powder and the binder. . And the green sheet 14 which shape | molded the produced | generated compound 12 in the sheet form is produced. Thereafter, a magnetic field is applied to the molded green sheet 14 to apply a magnetic field, and the green sheet 14 is deformed in consideration of the direction of the magnetic field of the green sheet 14 subjected to the magnetic field formation to form a final product shape. Do. Thereafter, the permanent magnet 1 is manufactured by sintering. In addition, the magnetic flux density distribution in the circumferential direction of the outer circumferential surface of the polar anisotropic ring magnet is measured by actual measurement or electromagnetic field analysis, and the amplitude of the harmonic component is the amplitude of the fundamental wave for the shape of the measured magnetic flux density distribution. The orientation direction of the magnetization easy axis of the polar anisotropic ring magnet is designed to be 1/10 or less, and the magnetization easy axis is oriented in the designed orientation direction. As a result, the amplitude of the harmonic component of the magnetic flux density distribution in the circumferential direction of the outer circumferential surface of the manufactured polar anisotropic ring magnet can be made sufficiently smaller than the amplitude of the fundamental wave, so the magnetic flux density distribution is designed in advance It is possible to get closer to the ideal shape. In addition, when the manufactured permanent magnet is installed in the rotating electrical machine, the change in magnetic flux in the air gap becomes smooth, so it is possible to reduce the torque ripple and realize noise reduction and vibration reduction of the rotating electrical machine. . In addition, harmonic loss (eddy current loss, hysteresis loss) can be reduced.
In addition, since the orientation direction of the magnetization easy axis is designed based on the shape of the measured magnetic flux density distribution, the waveform of the magnetic flux density distribution in the circumferential direction of the outer peripheral surface of the polar anisotropic ring magnet is more intended by the manufacturer. It is possible to approximate the shape to
In addition, since the mixture of the magnetic powder and the binder is formed, it is possible to improve the degree of orientation without rotating the magnet particles after orientation as compared with the case of using powder compacting or the like. Further, when performing magnetic field orientation on a molded body, the number of turns of current can be used, so that a large magnetic field strength can be secured during magnetic field orientation, and a long time magnetic field application can be performed with a static magnetic field. Therefore, it is possible to realize a high degree of orientation with less variation.
Moreover, it becomes possible to make the waveform of the magnetic flux density distribution in the circumferential direction of the outer peripheral surface of the polar anisotropic ring magnet to be manufactured approach an ideal sine wave shape. As a result, torque ripples can be reduced, and drive control of the rotating electrical machine can be accurately performed when installed in the rotating electrical machine.
In addition, since the orientation direction of the magnetization easy axis is feedback-designed based on the measured shape of the magnetic flux density distribution, the orientation design of the permanent magnet can be easily and accurately performed as compared with the prior art. As a result, it becomes possible to manufacture a permanent magnet having an orientation suitable for each rotation motor.
In addition, since the easy magnetization axis is oriented in the designed orientation direction by controlling the direction in which the magnetic field is applied to the molded body, it is possible to appropriately orient the easy magnetization axis in the direction intended by the manufacturer. Become.
In addition, since molding into a molded body is performed while manipulating the direction of the magnetization easy axis by deforming the mixture after orientation, even in the case where the magnetization easy axis is oriented in a complicated shape, it is highly oriented and dispersed. It becomes possible to realize less orientation. Therefore, even if the orientation design of the permanent magnet is complicated as compared with the prior art, it can be realized accurately.
Further, since the mixture is formed into a sheet and then oriented in a magnetic field to a sheet-like mixture, the mixture of the magnet powder and the binder is formed into a sheet-like green sheet, thereby further processing such as deformation into a formed body It is possible to easily carry out, and it becomes possible to more appropriately orient the magnetization easy axis. Also, productivity can be improved.

The present invention is not limited to the above-described embodiment, and it goes without saying that various improvements and modifications can be made without departing from the scope of the present invention.
For example, the pulverizing conditions, kneading conditions, molding conditions, magnetic field orientation process, calcination conditions, sintering conditions, etc. of the magnet powder are not limited to the conditions described in the above examples. For example, although the magnet raw material is ground by wet grinding using a bead mill in the above embodiment, it may be ground by dry grinding using a jet mill. Further, the atmosphere at the time of the calcination may be other than hydrogen atmosphere (for example, nitrogen atmosphere, He atmosphere, Ar atmosphere, etc.) as long as it is non-oxidative atmosphere. Also, the calcination process may be omitted. In that case, decarbonization will be performed in the process of a sintering process.

  Further, in the above embodiment, although the magnetic powder and binder are formed into a sheet shape and then magnetic orientation is performed, the magnetic powder may be formed into a shape other than the sheet shape. For example, it may be molded into a block shape. Even in that case, by deforming the mixture formed after the magnetic field orientation, it becomes possible to orient so as to properly focus the easy axis in one direction along the focusing axis.

  Further, in the above embodiment, after performing magnetic field orientation on a mixture of magnet powder and a binder, it is configured to be formed into a final product shape (for example, a fan shape shown in FIG. 1). Magnetic field orientation may be performed after molding into In that case, it becomes possible to properly orient the magnetization easy axis in the designed direction by controlling the direction of the magnetic field orientation to the compact molded into the final product shape.

  In the above embodiment, the orientation direction of the magnetization easy axis of the permanent magnet is designed so that the shape of the magnetic flux density distribution in the circumferential direction of the outer peripheral surface of the permanent magnet becomes a sine wave shape. It is also possible to design the orientation direction of the magnetization easy axis of the permanent magnet to be a shape. The shape of the magnetic flux density distribution to be realized can be appropriately changed according to the type and application of the permanent magnet.

  In the above embodiment, the orientation direction of the magnetization easy axis of the permanent magnet 1 is designed based on the measured shape of the magnetic flux density distribution on the outer peripheral surface of the permanent magnet 1, but the same method is used. The shape of the permanent magnet 1 may also be designed by this method. That is, the shape of the permanent magnet may be designed such that the shape of the magnetic flux density distribution on the outer peripheral surface of the permanent magnet 1 has a sine wave shape with a small harmonic component.

  Further, in the above embodiment, the orientation direction of the magnetization easy axis of the permanent magnet is designed based on the shape of the magnetic flux density distribution in the circumferential direction of the outer circumferential surface of the permanent magnet. It may be configured to be designed based on the distribution and the shape of the induced voltage. For example, after arranging a permanent magnet on the rotor or stator of the rotating electrical machine, the amplitude of the harmonic component of the shape of the magnetic flux density distribution in the air gap between the rotor and the stator becomes one tenth or less of the amplitude of the fundamental wave As described above, the orientation direction of the magnetization easy axis of the permanent magnet may be designed. In addition, with regard to the shape of the induced voltage generated by rotating the rotor of the rotating electrical machine in which the permanent magnet is arranged on the rotor or stator, the amplitude of the harmonic component is 1/10 or less of the amplitude of the fundamental wave. The orientation direction of the magnetization easy axis may be designed.

  Furthermore, in the above embodiment, after the magnet powder is formed into a plurality of fan-shaped shapes, they are joined to form a ring shape, but the magnet powder is directly formed into a ring shape without being formed into a fan shape. It is good. In that case, the green sheet 14 subjected to the magnetic field orientation may be deformed into a ring shape by deformation, or the magnetic field may be oriented after the mixture is formed into the ring shape.

  Moreover, it is possible to apply also to the rotary electric machine which arrange | positions a permanent magnet not on the rotor side but on the stator side. In that case, since the magnet is installed in the opposite direction, the magnetic flux inside the magnet is concentrated from the outer peripheral direction to the center direction. Furthermore, it is applicable not only to a motor but also to a generator.

  Further, in the above embodiment, although the magnet powder is formed and then calcinated in a hydrogen atmosphere or a mixed gas atmosphere of hydrogen and an inert gas, the magnet powder before formation is calcined to A permanent magnet may be manufactured by forming a magnetic powder which is a body into a molded body and thereafter performing sintering. With such a configuration, calcination is performed on powdery magnetic particles, so the surface area of the magnet to be calcined is large compared to the case where calcination is performed on molded magnetic particles. can do. That is, the amount of carbon in the calcined body can be more reliably reduced. However, in order to thermally decompose the binder by calcination treatment, it is desirable to carry out calcination treatment after molding.

  Further, in the present invention, an Nd-Fe-B based magnet is described as an example, but other magnets (for example, a samarium based cobalt magnet, an alnico magnet, a ferrite magnet, etc.) may be used. Further, in the present invention, the alloy composition of the magnet has the Nd component more than the stoichiometric composition, but may have a stoichiometric composition.

1 permanent magnet 2 rotor 12 compound 14 green sheet 30 molded body 31 sintered body

Claims (6)

A method of manufacturing a polar anisotropic ring magnet,
And measuring the magnetic flux density distribution in the circumferential direction of the outer peripheral surface by measurement or electromagnetic field analysis, and designing the orientation direction of the magnetization easy axis based on the measured shape of the magnetic flux density distribution,
In the step of designing the orientation direction,
Based on the shape of the measured magnetic flux density distribution, harmonic components are extracted by Fourier analysis;
The magnetization is easy so that the amplitude of the harmonic component of the shape of the magnetic flux density distribution in the circumferential direction of the outer peripheral surface is not more than one tenth of the amplitude of the fundamental wave by comparing the fundamental wave and the extracted harmonic wave component. Feedback design of the axis orientation direction,
A method of manufacturing a permanent magnet, comprising: orienting a magnetization easy axis in the designed orientation direction. In the step of designing the orientation direction, designing the orientation direction of the magnetization easy axis of the polar anisotropic ring magnet so that the shape of the fundamental wave of the measured magnetic flux density distribution approaches a sine wave shape more The method of manufacturing a permanent magnet according to claim 1 , characterized in that: Grinding the magnet raw material into magnet powder,
Generating a mixture of the pulverized magnet powder and a binder;
Forming the mixture into a shaped body having a predetermined shape;
Orienting the magnetic field with respect to the compact;
Sintering the magnetic field-oriented compact by holding it at a firing temperature,
The method for manufacturing a permanent magnet according to claim 1 or 2 , wherein in the step of orienting the magnetic field, the magnetization easy axis is oriented in the orientation direction designed in the step of designing the orientation direction. The permanent magnet according to claim 3 , wherein in the step of orienting the magnetic field, the easy axis of magnetization is oriented in the designed orientation direction by controlling the direction in which the magnetic field is applied to the compact. Manufacturing method. In the step of orienting the magnetic field, a magnetic field is applied to the mixture, and the direction of the axis of easy magnetization is manipulated by deforming the mixture to which the magnetic field is applied into the molded body, and the magnetic field to the molded body Orientation,
4. A permanent magnet according to claim 3 , wherein the axis of easy magnetization is oriented in the designed orientation direction by controlling the direction of applying a magnetic field to the mixture or the deformation mode of the mixture. Method. The method of manufacturing a permanent magnet according to claim 5 , wherein, in the step of orienting the magnetic field, the mixture is formed into a sheet, and then the magnetic field is oriented to the sheet-like mixture.

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