JP2016032025A - Permanent magnet and method of manufacturing permanent magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a permanent magnet that can be magnetized reliably up to the saturation point, and to provide a method of manufacturing a permanent magnet.SOLUTION: A compound 12 is produced by pulverizing a magnet material into magnet powder, and then mixing the magnet powder thus pulverized and a binder. A plurality of sintered compacts 31 are then created by performing the molding, magnetic field orientation and sintering of the compound 12 thus produced. Subsequently, the plurality of sintered compacts 31 are magnetized by applying a magnetic field in a direction based on the orientation direction of the easy axis of magnetization, and the plurality of sintered compacts 31 thus magnetized are bonded to each other, thus producing a conjugate of the plurality of sintered compacts 31, i.e., a permanent magnet in product shape.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a permanent magnet and a method for manufacturing the permanent magnet.

  In recent years, in machine tools, vehicles, aircraft, wind power engines, etc., a generator that converts mechanical kinetic energy transmitted from an engine into electrical energy, or a motor that converts electrical energy into mechanical kinetic energy ( A rotating electrical machine such as an electric motor is generally used. Further, there is a demand for further increases in torque and power generation amount of the rotating electrical machine.

  Here, as a manufacturing method of a permanent magnet used for a rotating electrical machine, a powder sintering method has been generally used. Here, in the powder sintering method, first, magnet powder obtained by pulverizing raw materials by a jet mill (dry pulverization) or the like is manufactured. Thereafter, the magnet powder is put into a mold and press-molded into a desired shape. And it manufactures by sintering the solid magnet powder shape | molded by the desired shape at predetermined temperature (for example, 1100 degreeC in a Nd-Fe-B type magnet) (for example, Unexamined-Japanese-Patent No. 2-266503). In general, permanent magnets are magnetically oriented by applying a magnetic field from the outside in order to improve magnetic characteristics. In the conventional method for producing a permanent magnet by powder sintering, a magnet powder is filled into a mold at the time of press molding, and a magnetic field is applied to orient the magnetic field, and then pressure is applied to form a compacted compact. Was. Moreover, in the manufacturing method of the permanent magnet by other extrusion molding methods, injection molding methods, rolling molding methods, etc., a magnet was molded by applying pressure in an atmosphere to which a magnetic field was applied. Accordingly, it is possible to form a molded body in which the easy magnetization (C-axis) direction of each magnet particle constituting the permanent magnet is aligned with the magnetic field application direction.

  Here, there are axial anisotropy, radial anisotropy, polar anisotropy and the like as a method of aligning the easy magnetization axes of the anisotropic magnets. In addition, when using an anisotropic magnet for a rotary motive, instead of orienting the easy axis of magnetization of each magnet particle in the same direction (that is, in parallel), for the purpose of reducing torque ripple and improving driving force, The easy axis of magnetization has been oriented in the direction in which the magnetic flux of the magnetized anisotropic magnet is concentrated (for example, JP-A-2005-287181).

JP-A-2-266503 (page 5) Japanese Patent Laying-Open No. 2005-287181 (5th page, FIG. 2)

  However, when the easy magnetization axis is oriented in a complicated direction as in the technique described in Patent Document 2, a permanent magnet (for example, parallel orientation or radial orientation) in which the easy magnetization axis is oriented in a general linear shape. As compared with permanent magnets, there is a problem that magnetization is difficult.

  Here, the permanent magnet can be magnetized by, for example, a static magnetic field method using a magnetizing coil, a pulse magnetic field method using a magnetizing yoke or a capacitor, or the like. When magnetizing a permanent magnet, it is important to apply a magnetic field as parallel as possible with respect to the easy magnetization axis in any method. For example, in FIG. 13, a case where magnetization is performed by applying an external magnetic field of 20 kOe to the sintered body 101 that is the source of the permanent magnet will be described. Here, when the direction X of the external magnetic field and the direction Y of the magnetization easy axis (C axis) of the sintered body 101 are shifted by an angle θ, the magnitude of the external magnetic field that is substantially effective for magnetization is “20 kOe. × cos θ ”. As a result, when the angle θ is increased, the sintered body 101 may not be magnetized to the saturation point (full magnetization). A permanent magnet that is not magnetized to the saturation point has a problem that the magnetic performance is lowered and demagnetization is easier than a permanent magnet that is magnetized to the saturation point. On the other hand, it was possible to increase the external magnetic field and magnetize to the saturation point, but the production cost became very high and the work efficiency of magnetization was reduced.

  The present invention has been made to solve the above-mentioned problems, and is possible with respect to the direction of the easy axis even if the easy axis is oriented in a complicated direction in the permanent magnet magnetization process. An object of the present invention is to provide a permanent magnet that can apply magnetic fields in parallel as much as possible, and can be surely magnetized to the saturation point, and a method for manufacturing the permanent magnet.

  In order to achieve the above object, a permanent magnet according to claim 1 of the present application includes a step of pulverizing a magnet raw material into magnet powder, and a plurality of sintering by performing molding, magnetic field orientation and sintering on the pulverized magnet powder. A step of obtaining a body, a step of magnetizing the plurality of sintered bodies by applying a magnetic field in a direction based on an orientation direction of an easy magnetization axis for each of the sintered bodies, and a plurality of the magnetized pieces It is manufactured by a step of obtaining a joined body in which a plurality of sintered bodies are joined by joining the sintered bodies together.

  A permanent magnet according to claim 2 is the permanent magnet according to claim 1, wherein in the magnetization step, a magnetic field is applied within a predetermined angle with respect to the orientation direction of the easy axis of magnetization of the sintered body. It is characterized by being magnetized.

  The permanent magnet according to claim 3 is the permanent magnet according to claim 2, wherein the orientation direction of the easy axis of the sintered body has a curved shape, and in the magnetization step, the sintering Magnetization is performed by applying a magnetic field within a predetermined angle with respect to an approximate straight line in the orientation direction of the easy axis of magnetization of the body.

  A permanent magnet according to a fourth aspect is the permanent magnet according to any one of the first to third aspects, wherein in the step of obtaining the plurality of sintered bodies, the magnetic powder oriented in the magnetic field is formed. A plurality of the sintered bodies are obtained by sintering after dividing the body into a plurality of parts.

  A permanent magnet according to a fifth aspect is the permanent magnet according to any one of the first to third aspects, wherein in the step of obtaining the plurality of sintered bodies, the magnetic powder oriented in the magnetic field is formed. A plurality of the sintered bodies are obtained by dividing the body into a plurality of parts after sintering.

  A permanent magnet according to claim 6 is the permanent magnet according to claim 4 or claim 5, wherein in forming the molded body, a mixture in which the pulverized magnet powder and a binder are mixed is formed. It is characterized by doing.

  A permanent magnet according to a seventh aspect is the permanent magnet according to the sixth aspect, wherein a magnetic field is applied to the mixture, and the mixture to which the magnetic field is applied is transformed into the compact. The direction of the easy axis of magnetization is manipulated to perform magnetic field orientation on the compact.

  Moreover, the permanent magnet which concerns on Claim 8 is a permanent magnet in any one of Claim 1 thru | or 7, Comprising: The said sintered compact is joined by the adhesive agent, It is characterized by the above-mentioned.

  A permanent magnet according to a ninth aspect is the permanent magnet according to any one of the first to eighth aspects, wherein the combined body is easily magnetized so as to be focused in one direction along the focusing axis. The axis is oriented with an inclination.

  The method for producing a permanent magnet according to claim 10 obtains a plurality of sintered bodies by performing a step of pulverizing a magnet raw material into magnet powder and molding, magnetic field orientation and sintering of the pulverized magnet powder. A step of magnetizing the plurality of sintered bodies by applying a magnetic field in a direction based on the orientation direction of the easy axis of each of the sintered bodies, and the plurality of magnetized sintered bodies A plurality of the sintered bodies are bonded to each other to obtain a bonded body.

  A permanent magnet manufacturing method according to claim 11 is the permanent magnet manufacturing method according to claim 10, wherein, in the magnetization step, a predetermined direction is set with respect to an orientation direction of an easy axis of magnetization of the sintered body. It is characterized by being magnetized by applying a magnetic field within an angle.

  Moreover, the manufacturing method of the permanent magnet which concerns on Claim 12 is a manufacturing method of the permanent magnet of Claim 11, Comprising: The orientation direction of the magnetization easy axis | shaft of the said sintered compact has a curvilinear shape, The said magnetization The step is characterized in that the magnetic field is magnetized by applying a magnetic field within a predetermined angle with respect to an approximate straight line of the orientation direction of the easy axis of magnetization of the sintered body.

  A method for manufacturing a permanent magnet according to claim 13 is the method for manufacturing a permanent magnet according to any one of claims 10 to 12, wherein in the step of obtaining the plurality of sintered bodies, magnetic field orientation is performed. The magnet powder compact is divided into a plurality of parts and then sintered to obtain a plurality of the sintered bodies.

  A method for manufacturing a permanent magnet according to claim 14 is the method for manufacturing a permanent magnet according to any one of claims 10 to 12, wherein in the step of obtaining the plurality of sintered bodies, magnetic field orientation is performed. In addition, a plurality of the sintered bodies are obtained by dividing the magnet powder compact into a plurality of parts after sintering.

  Moreover, the manufacturing method of the permanent magnet which concerns on Claim 15 is a manufacturing method of the permanent magnet of Claim 13 or Claim 14, Comprising: In shaping | molding of the said molded object, the said pulverized magnet powder and a binder are used. It is characterized by forming a mixed mixture.

  Moreover, the manufacturing method of the permanent magnet which concerns on Claim 16 is a manufacturing method of the permanent magnet of Claim 15, Comprising: While applying a magnetic field with respect to the said mixture, the said mixture to which the magnetic field was applied is said shaping | molding. The magnetic field orientation with respect to the compact is performed by manipulating the direction of the easy magnetization axis by deforming into a body.

  A method for manufacturing a permanent magnet according to claim 17 is the method for manufacturing a permanent magnet according to any one of claims 10 to 16, wherein the sintered body is bonded in the step of obtaining the combined body. It is characterized by joining with an agent.

  Furthermore, the manufacturing method of the permanent magnet which concerns on Claim 18 is a manufacturing method of the permanent magnet in any one of Claim 10 thru | or 17, Comprising: The said coupling body goes to one direction along a focusing axis. It is characterized in that the easy axis of magnetization is oriented so as to be focused.

  According to the permanent magnet of claim 1 having the above-described configuration, magnetization is performed by applying a magnetic field in a direction based on the orientation direction of the easy axis of each sintered body in a state of being divided into a plurality of sintered bodies. Since the final permanent magnet is formed by joining a plurality of magnetized sintered bodies to each other, it is assumed that the easy magnetization axis of the permanent magnet is oriented in a complicated direction in the permanent magnet magnetization process. Also, the magnetic field can be applied as parallel as possible to the direction of the easy axis of magnetization. As a result, the permanent magnet can be surely magnetized (full magnetization) to the saturation point.

  Further, according to the permanent magnet of the second aspect, in the magnetizing step of the permanent magnet, magnetization is performed by applying a magnetic field within a predetermined angle with respect to the orientation direction of the easy axis of the sintered body. Even when a magnetic field of the same magnitude is applied, the magnetic field contributing to magnetization can be increased, and magnetization can be performed more efficiently.

  In addition, according to the permanent magnet of the third aspect, even in the case of a permanent magnet having an easy magnetization axis oriented in a complicated curved shape, it is possible with respect to the direction of the easy magnetization axis in the permanent magnet magnetization process. Magnetic fields can be applied in parallel as long as possible. As a result, magnetization can be performed more efficiently, and the permanent magnet can be surely magnetized to the saturation point (full magnetization).

  Further, according to the permanent magnet of claim 4, since the magnetic powder-oriented magnet powder compact is divided into a plurality of parts and sintered to obtain a plurality of sintered bodies to be magnetized. Even when the easy magnetization axis of the body is oriented in a complicated direction, the direction of the easy magnetization axis of each sintered body to be magnetized can be made as close to a straight line as possible. . Further, by dividing the molded body before sintering, the division work can be easily performed.

  Moreover, according to the permanent magnet of claim 5, since the magnetic powder-oriented magnet powder compact is sintered and divided into a plurality of sintered bodies to be magnetized, Even when the easy magnetization axis of the body is oriented in a complicated direction, the direction of the easy magnetization axis of each sintered body to be magnetized can be made as close to a straight line as possible. . In addition, even when the compact is deformed or deformed due to sintering, it is possible to appropriately join the sintered bodies after magnetization.

Further, according to the permanent magnet of claim 6, since the mixture of the magnet powder and the binder is molded, the magnet particles do not rotate after the orientation, compared with the case of using compacting or the like, It is possible to improve the degree of orientation. In addition, when magnetic field orientation is performed on a mixture with a binder, the number of current turns can be used, so that it is possible to ensure a large magnetic field strength when performing magnetic field orientation, and long-term magnetic field application with a static magnetic field. Therefore, it is possible to realize a high degree of orientation with little variation.
Furthermore, the realization of high orientation with little variation leads to a reduction in variation in shrinkage due to sintering. That is, the uniformity of the product shape after sintering can be ensured. As a result, it can be expected that the burden on the external processing after sintering is reduced and the stability of mass production is greatly improved.

  In addition, according to the permanent magnet of the seventh aspect, it is possible to correct the orientation direction by deforming the mixture once magnetically oriented, and to perform magnetic field orientation of the compact. As a result, it is possible to perform a highly oriented orientation with little variation. Further, when the mixture is formed into a molded body, the orientation direction can be corrected simultaneously with the deformation to the molded body. As a result, the molding process and the orientation process of the permanent magnet can be performed in one process, and the productivity can be improved.

  Moreover, according to the permanent magnet of the eighth aspect, since the sintered body is joined by the adhesive, it becomes possible to appropriately bond the sintered bodies after magnetization. Moreover, even if the permanent magnet is divided, it is possible to prevent the magnetic characteristics of the finally produced permanent magnet from being deteriorated.

  Further, according to the permanent magnet of the ninth aspect, since the easy magnetization axis is inclined so as to be focused in one direction along the focusing axis, the surface on which the magnetic pole is formed is magnetized after magnetization. It is possible to concentrate the magnetic flux appropriately, thereby improving the maximum magnetic flux density and preventing variations in the magnetic flux density. In particular, if permanent magnets are arranged on the rotor or stator of a rotating electric machine, the maximum magnetic flux density is improved by concentrating the magnetic flux on the air gap side, and the torque and power generation amount of the rotating electric machine on which the permanent magnets are arranged can be increased. As a result, torque ripple can be reduced.

  Further, according to the method of manufacturing a permanent magnet according to claim 10, the permanent magnet is applied by applying a magnetic field in a direction based on the orientation direction of the easy axis of magnetization for each sintered body in a state of being divided into a plurality of sintered bodies. Since a final permanent magnet is formed by joining a plurality of magnetized and magnetized sintered bodies to each other, the magnetization easy axis of the permanent magnet is oriented in a complicated direction in the permanent magnet magnetization process. The magnetic field can be applied as parallel as possible to the direction of the easy axis of magnetization. As a result, the permanent magnet can be surely magnetized (full magnetization) to the saturation point.

  According to the method for manufacturing a permanent magnet according to claim 11, the permanent magnet is magnetized by applying a magnetic field within a predetermined angle with respect to the orientation direction of the easy axis of the sintered body in the permanent magnet magnetization step. Thus, even when a magnetic field of the same magnitude is applied, the magnetic field contributing to magnetization can be increased, and magnetization can be performed more efficiently.

  According to the method for manufacturing a permanent magnet according to claim 12, even in the case of a permanent magnet having an easy magnetization axis oriented in a complicated curved shape, in the magnetization process of the permanent magnet, On the other hand, the magnetic field can be applied as parallel as possible. As a result, magnetization can be performed more efficiently, and the permanent magnet can be surely magnetized to the saturation point (full magnetization).

  According to the method for manufacturing a permanent magnet according to claim 13, the magnetic powder-oriented magnet powder shaped body is divided into a plurality of pieces and then sintered to obtain a plurality of sintered bodies to be magnetized. Therefore, even when the easy axis of magnetization of the compact is oriented in a complicated direction, the direction of the easy axis of magnetization of each sintered body to be magnetized can be made as close to a straight line as possible. It becomes possible. Further, by dividing before sintering, it is possible to easily perform the dividing operation.

  Further, according to the method for manufacturing a permanent magnet according to claim 14, the magnetic powder oriented magnetic powder compact is sintered and then divided into a plurality of sintered bodies to be magnetized. Therefore, even when the easy axis of magnetization of the compact is oriented in a complicated direction, the direction of the easy axis of magnetization of each sintered body to be magnetized can be made as close to a straight line as possible. It becomes possible. In addition, even when the compact is deformed or deformed due to sintering, it is possible to appropriately join the sintered bodies after magnetization.

Further, according to the method for producing a permanent magnet according to claim 15, since the mixture of the magnet powder and the binder is molded, the magnet particles rotate after the orientation as compared with the case of using compacting or the like. In addition, the degree of orientation can be improved. In addition, when magnetic field orientation is performed on a mixture with a binder, the number of current turns can be used, so that it is possible to ensure a large magnetic field strength when performing magnetic field orientation, and long-term magnetic field application with a static magnetic field. Therefore, it is possible to realize a high degree of orientation with little variation.
Furthermore, the realization of high orientation with little variation leads to a reduction in variation in shrinkage due to sintering. That is, the uniformity of the product shape after sintering can be ensured. As a result, it can be expected that the burden on the external processing after sintering is reduced and the stability of mass production is greatly improved.

  In addition, according to the method for manufacturing a permanent magnet of the sixteenth aspect, it is possible to correct the orientation direction by deforming the magnetically oriented mixture, and to perform magnetic field orientation of the compact. As a result, it is possible to perform a highly oriented orientation with little variation. Further, when the mixture is formed into a molded body, the orientation direction can be corrected simultaneously with the deformation to the molded body. As a result, the molding process and the orientation process of the permanent magnet can be performed in one process, and the productivity can be improved.

  Further, according to the method for manufacturing a permanent magnet according to claim 17, since the sintered body is joined by the adhesive, it becomes possible to appropriately bond the sintered bodies after magnetization. Moreover, even if the permanent magnet is divided, it is possible to prevent the magnetic characteristics of the finally produced permanent magnet from being deteriorated.

  Furthermore, according to the method of manufacturing a permanent magnet according to claim 18, the easy magnetization axis is inclined and oriented so as to focus in one direction along the focusing axis. It is possible to concentrate the magnetic flux appropriately after magnetizing, thereby improving the maximum magnetic flux density and preventing variations in the magnetic flux density. In particular, if permanent magnets are arranged on the rotor or stator of a rotating electric machine, the maximum magnetic flux density is improved by concentrating the magnetic flux on the air gap side, and the torque and power generation amount of the rotating electric machine on which the permanent magnets are arranged can be increased. As a result, torque ripple can be reduced.

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 by which the permanent magnet is 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. It is the figure which showed the magnetization easy axis direction of the permanent magnet. It is the figure which showed the polar anisotropic orientation formed by the permanent magnet arrange | positioned on the surface of a rotor. It is explanatory drawing which showed the manufacturing process of the permanent magnet which concerns on this invention. It is explanatory drawing which showed the manufacturing process of the permanent magnet which concerns on this invention. It is explanatory drawing which showed the formation process and magnetic field orientation 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 the easy magnetization axis direction. It is the figure explaining the temperature rising aspect of the calcining process among the manufacturing processes of the permanent magnet which concerns on this invention. It is the figure explaining the magnetization process especially among the manufacturing processes of the permanent magnet which concerns on this invention. It is a figure explaining the problem of the prior art.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment embodying a permanent magnet and a method for manufacturing a 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, a permanent magnet 1 according to the present invention is a permanent magnet having a saddle shape (segment type). As shown in FIG. 2, a plurality of surface magnet type motors (or generators) are arranged on the surface of the rotor 2 to constitute a surface magnet type motor (or generator). FIG. 2 is a view showing the rotor 2 of the SPM motor in which the permanent magnet 1 is arranged. In the following embodiment, an example in which the permanent magnet 1 has a segment shape will be described. However, the shape of the permanent magnet 1 can be appropriately changed depending on the shape of the rotating electrical machine to be arranged, the number of arrangements, and the like. For example, it may be a fan shape, a bow shape, or a rectangular parallelepiped shape. Further, in addition to the surface magnet type rotary electric machine, the present invention can also be applied to an embedded magnet type rotary electric machine such as an IPM motor, a linear motor, or the like.

  The permanent magnet 1 according to the present invention is made of an Nd—Fe—B based magnet. In addition, content of each component shall be Nd: 27-40 wt%, B: 0.8-2 wt%, Fe (electrolytic iron): 60-70 wt%. In order to improve magnetic properties, other elements such as Dy, Tb, Co, Cu, Al, Si, Ga, Nb, V, Pr, Mo, Zr, Ta, Ti, W, Ag, Bi, Zn, and Mg are added. May contain a small amount.

  Further, as shown in FIG. 1, the permanent magnet 1 is constituted by joining a plurality of magnetized sintered bodies 3 and bonding them together with an adhesive made of resin or the like (for example, a mixture of resin and solvent). Has been. An additive such as a filler may be added to the adhesive. Further, the number and shape of the sintered bodies 3 constituting one permanent magnet 1 are configured to be appropriately changed according to the orientation direction of the easy magnetization axis of the permanent magnet 1. Specifically, when the sintered bodies 3 are magnetized, a magnetic field can be applied as parallel as possible to the orientation direction of the easy axis of each sintered body 3 (that is, each sintered body 3). The permanent magnet 1 is divided into a plurality of sintered bodies 3 so that the orientation direction of the easy axis of magnetization is as linear as possible in one direction. Therefore, the number of the sintered bodies 3 constituting one permanent magnet 1 increases as the easy magnetization axis is oriented in a complicated shape. For example, in the example shown in FIG. 1, the permanent magnet 1 is configured by joining four sintered bodies 3 having a substantially triangular prism shape.

  Further, the number of permanent magnets 1 arranged with respect to the rotor 2 is a number corresponding to the number of poles formed around the rotor 2. For example, when the number of poles is set to twelve, twelve permanent magnets as shown in FIG. 1 are arranged at equal intervals with respect to the rotor 2.

  Furthermore, each sintered compact 3 which comprises the permanent magnet 1 is formed by the molded object (green molded object) which shape | molded the mixture which mixed magnet powder and the binder as mentioned later. Further, the sintered body 3 is formed by once forming the mixture into a product shape of the permanent magnet 1 (for example, a segment shape in the example shown in FIG. 1), performing magnetic field orientation, and then dividing the formed body. The molded body may be divided before or after the molded body is sintered. In addition, the product shape is not formed by directly forming the mixture into a product shape, but once it is formed into a shape other than the product shape (for example, a sheet shape, a block shape, etc.), followed by punching, cutting, deformation, etc. It is good also as a structure. In particular, if the mixture is once formed into a sheet shape and then processed into a product shape, productivity can be improved by producing in a continuous process, and molding accuracy can also be improved. When making a mixture into a sheet shape, it is set as the thin film-like sheet member provided with thickness of 0.05 mm-10 mm (for example, 1 mm), for example. Even in the case of a sheet shape, a large permanent magnet 1 can be manufactured if a plurality of sheets are laminated.

  Moreover, the permanent magnet 1 according to the present invention is an anisotropic magnet, and as shown in FIG. 3, the permanent magnet 1 is in one direction along the focusing axis P passing through the magnet surface (in FIG. 3, the air gap side). The easy magnetization axis (C axis) is oriented in the direction of the convex surface.

  In the example shown in FIG. 3, the focusing axis P is set so as to pass near the center of the permanent magnet 1, but it may be set to the right side or the left side instead of near the center. Further, when the permanent magnet 1 is disposed on the rotor 2, as shown in FIG. 3, the easy axis of magnetization in the outward direction (that is, the air gap side) from both ends to the center along the circumferential direction of the rotor 2. Oriented so that (C axis) is inclined. More specifically, the easy magnetization axis is formed along an exponential curve. As a result, when the permanent magnet 1 is arranged on the rotor 2 and magnetized, the magnetic flux inside the magnet concentrates from the center direction of the rotor 2 to the outer side (that is, the air gap side) (that is, the magnetic flux on the magnet surface). Density increases).

  Further, as shown in FIG. 4, the easy magnetization axis may be oriented so as to converge linearly in one direction along the focusing axis P. Even in that case, when the permanent magnet 1 is arranged on the rotor 2 and magnetized, the magnetic flux inside the magnet concentrates from the center direction of the rotor 2 to the outer side (that is, the air gap side) (ie, The magnetic flux density on the magnet surface is increased).

  Further, for example, even when the permanent magnet 1 is disposed in the rotor 2 of an embedded rotary electric machine such as an IPM motor, as shown in FIG. 5, from both ends to the center side along the circumferential direction of the rotor 2, Oriented so that the easy axis (C-axis) is inclined toward the outer peripheral side. As a result, when the permanent magnet 1 is housed and magnetized in the housing portion formed inside the rotor 2, the magnetic flux inside the magnet is concentrated from the center direction of the rotor 2 to the outer side (that is, the air gap side). (That is, the magnetic flux density on the rotor surface is increased).

  Further, as described above, the permanent magnet 1 is configured by joining a plurality of sintered bodies 3, but the orientation direction of the easy axis of magnetization of each sintered body 3 is a straight line along one direction as much as possible. The permanent magnet 1 is divided into sintered bodies 3 so as to have a shape. Therefore, for example, in an example oriented so as to converge in one direction along the focusing axis P as shown in FIGS. 3 to 5, the normal direction relative to the orientation direction of the line along the focusing axis P and the easy magnetization axis In addition, the permanent magnet 1 is divided by a line that divides the permanent magnet 1 into approximately four equal parts, and is constituted by a total of four sintered bodies 3.

  Further, in the permanent magnet 1 according to the present invention, since the magnetic field is applied to the mixture of the magnet powder and the binder as will be described later, the magnetic particles are aligned by the pressure applied after the orientation as in compacting. It is possible to improve the degree of orientation without rotating. Moreover, since there is no variation in the density distribution of the magnet powder unlike the PLP method, the near net shape property is improved. Furthermore, after applying a magnetic field to the mixture before forming into a product shape (for example, the segment mold shown in FIG. 1) and performing orientation, the mixture is formed in consideration of the direction of the easy axis of magnetization of the mixture (for example, If it is deformed and formed into a product shape, the direction of the easy magnetization axis can be manipulated in the process of forming the product shape. That is, it is possible to properly orient the easy magnetization axis in the direction intended by the manufacturer. As a result, a permanent magnet having an easy axis oriented in a complicated direction (for example, an anisotropic magnet oriented so that the easy axis can be focused in a specific direction as shown in FIG. 3) can be easily and accurately realized. Is possible.

  Then, as shown in FIG. 3, when the permanent magnet 1 with the easy axis oriented is arranged around the rotor 2 and magnetized so that the adjacent permanent magnets 1 have different poles, FIG. 6 shows. Such polar anisotropic orientation can be realized. Thereby, a sinusoidal magnetic flux density distribution can be obtained. And in a rotating electrical machine equipped with a permanent magnet having polar anisotropic orientation, there is an advantage that torque and power generation amount of the rotating electrical machine can be improved, torque ripple can be reduced, and driving control of the rotating electrical machine can be performed accurately. is there.

（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） In the present invention, in particular, when the permanent magnet 1 is manufactured, a resin, a long-chain hydrocarbon, a fatty acid ester, a mixture thereof, or the like is used as the binder mixed with the magnet powder.
Furthermore, when a resin is used for the binder, it is preferable to use a polymer that does not contain an oxygen atom in the structure and has a depolymerization property. In addition, as described later, in order to reuse the residue of the mixture generated when the mixture of the magnet powder and the binder is formed into a desired shape (for example, a segment type), and in a state where the mixture is heated and softened, the magnetic field orientation is performed. For this purpose, a thermoplastic resin is used. Specifically, the polymer which consists of 1 type, or 2 or more types of polymers or copolymers chosen from the monomer shown 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 satisfying 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) that is a polymer of 1,3-butadiene. Rubber, BR), polystyrene as a polymer of styrene, styrene-isoprene block copolymer (SIS) as a copolymer of styrene and isoprene, butyl rubber (IIR) as a copolymer of isobutylene and isoprene, styrene and butadiene A styrene-butadiene block copolymer (SBS) which is a copolymer of 2-methyl-1-pentene, a 2-methyl-1-pentene polymer which is a polymer of 2-methyl-1-pentene, and a polymer of 2-methyl-1-butene. A 2-methyl-1-butene polymer, a polymer of α-methylstyrene. That there is α- methyl styrene polymer resin. In addition, it is desirable to add a low molecular weight polyisobutylene to the α-methylstyrene polymer resin in order to give flexibility. The resin used for the binder may include a small amount of a polymer or copolymer of a monomer containing an oxygen atom (for example, polybutyl methacrylate, polymethyl methacrylate, etc.). Furthermore, a monomer that does not correspond to the general formula (1) may be partially copolymerized. Even in that case, it is possible to achieve the object of the present invention.
In addition, as a resin used for the binder, a thermoplastic resin that softens at 250 ° C. or lower in order to appropriately perform magnetic field orientation, more specifically, a thermoplastic resin having a glass transition point or a flow start temperature of 250 ° C. or lower is used. Is desirable.

  On the other hand, when a long-chain hydrocarbon is used as the binder, it is preferable to use a long-chain saturated hydrocarbon (long-chain alkane) that is solid at room temperature and liquid at room temperature or higher. Specifically, it is preferable to use a long-chain saturated hydrocarbon having 18 or more carbon atoms. Then, when the mixture of the magnetic powder and the binder is magnetically oriented as described later, the magnetic field orientation is performed in a state where the mixture is heated and softened at a temperature equal to or higher than the glass transition point of the long-chain hydrocarbon or the flow start temperature.

  Similarly, when a fatty acid ester is used as the binder, it is preferable to use methyl stearate, methyl docosanoate or the like that is solid at room temperature and liquid at room temperature or higher. Then, when the mixture of the magnet powder and the binder is magnetically oriented as described later, the magnetic field orientation is performed in a state where the mixture is heated and softened at a temperature equal to or higher than the flow start temperature of the fatty acid ester.

  By using a binder that satisfies the above conditions as a binder to be mixed with the magnet powder, the amount of carbon and oxygen contained in the magnet can be reduced. Specifically, the amount of carbon remaining in the magnet after sintering is 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.

  Further, the amount of the binder added is an amount that appropriately fills the gaps between the magnet particles in order to improve the thickness accuracy of the molded body when molding the slurry or the heated and melted compound. For example, the ratio of the binder to the total amount of the magnet 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%.

[Permanent magnet manufacturing method]
Next, a method for manufacturing the permanent magnet 1 according to the present invention will be described with reference to FIGS. 7 and 8 are explanatory views showing manufacturing steps of the permanent magnet 1 according to the present embodiment.

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

  Next, the coarsely pulverized magnet powder 10 is finely pulverized by a wet method using a bead mill 11 or a dry method using a jet mill. For example, in fine pulverization using a wet method using a bead mill 11, the coarsely pulverized magnet powder 10 is finely pulverized in a solvent to a predetermined particle size (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 the wet pulverization is dried by vacuum drying or the like, and the dried magnet powder is taken out. Moreover, there is no restriction | limiting in particular in the kind of solvent used for grinding | pulverization, Alcohols, such as isopropyl alcohol, ethanol, methanol, Esters, such as ethyl acetate, Lower hydrocarbons, such as pentane and hexane, Aromatics, such as benzene, toluene, xylene , Ketones, mixtures thereof and the like. In addition, Preferably, the solvent which does not contain an oxygen atom in a solvent is used.

  On the other hand, in fine pulverization using a dry method using a jet mill, coarsely pulverized magnet powder is (a) in an atmosphere composed of an inert gas such as nitrogen gas, Ar gas, and He gas having substantially 0% oxygen content. Or (b) Finely pulverizing by a jet mill in an atmosphere made of an inert gas such as nitrogen gas, Ar gas, and He gas with an oxygen content of 0.0001 to 0.5%, A fine powder having an average particle diameter of 0.7 μm to 5.0 μm. The oxygen concentration of substantially 0% is not limited to the case where the oxygen concentration is completely 0%, but may contain oxygen in such an amount that a very small amount of oxide film is formed on the surface of the fine powder. Means good.

  Next, the magnet powder finely pulverized by the bead mill 11 or the like is molded into a desired shape. The magnet powder is molded by molding a mixture of magnet powder and binder. In the following examples, a magnetic field is applied by applying a magnetic field in a state where the mixture is once formed in a shape other than the product shape, and then the product shape (for example, as shown in FIG. 1) is performed by punching, cutting, deformation, or the like. Segment type). In particular, in the following examples, the mixture is once formed into a sheet-shaped green molded body (hereinafter referred to as a green sheet) to obtain a product shape. In addition, when the mixture is formed into a sheet shape, for example, hot melt coating that forms a sheet shape after heating a compound in which a magnet powder and a binder are mixed, or a slurry containing a magnet powder, a binder, and an organic solvent. There is molding by slurry coating or the like to form a sheet by coating the substrate on a substrate.

Hereinafter, green sheet forming using hot melt coating will be described.
First, a binder is mixed with magnet powder finely pulverized by a bead mill 11 or the like to prepare a clay-like mixture (compound) 12 composed of magnet powder and binder. Here, as the binder, a resin, a long-chain hydrocarbon, a fatty acid ester, a mixture thereof, or the like is used as described above. For example, when a resin is used, a thermoplastic resin made of a depolymerizable polymer that does not contain an oxygen atom in the structure is used. On the other hand, when a long-chain hydrocarbon is used, the resin is solid at room temperature or above room temperature. It is preferable to use a long-chain saturated hydrocarbon (long-chain alkane) that is liquid. Moreover, when using fatty acid ester, it is preferable to use methyl stearate, methyl docosanoate, or the like. In addition, as described above, the amount of the binder is such that the ratio of the binder to the total amount of the magnet powder and the binder in the compound 12 after the addition is 1 wt% to 40 wt%, more preferably 2 wt% to 30 wt%, still more preferably 3 wt%. % To 20 wt%.

  In addition, an additive for promoting orientation may be added to the compound 12 in order to improve the degree of orientation in a magnetic field orientation step performed later. As the additive for promoting the orientation, for example, a hydrocarbon-based additive is used, and it is particularly preferable to use an additive having polarity (specifically, an acid dissociation constant pKa of less than 41). Moreover, the addition amount of the additive depends on the particle diameter of the magnet powder, and it is necessary to increase the addition amount as the particle diameter of the magnet powder is smaller. The specific addition amount is 0.1 part to 10 parts, more preferably 1 part to 8 parts, with respect to the magnet powder. The additive added to the magnet powder adheres to the surface of the magnet particles and has a role of assisting the rotation of the magnet particles in the magnetic field orientation process described later. As a result, orientation is easily performed when a magnetic field is applied, and the easy magnetization axis directions of the magnet particles can be aligned in the same direction (that is, the degree of orientation can be increased). In particular, when a binder is added to the magnet powder, since the binder is present on the particle surface, the frictional force at the time of orientation is increased and the orientation of the particles is lowered, so that the effect of adding the additive is further increased.

  The binder is added in an atmosphere made 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 putting the magnet powder and the binder into a stirrer and stirring with the stirrer. In addition, heating and stirring may be performed to promote kneading properties. The mixing of the magnet powder and the binder is preferably performed in an atmosphere made of an inert gas such as nitrogen gas, Ar gas, or He gas. In particular, when the magnet powder is pulverized by a wet method, the binder is added to the solvent without kneading the magnet powder from the solvent used for pulverization, and then the solvent is volatilized. It is good also as a structure to obtain.

  Subsequently, a green sheet is created by forming the compound 12 into a sheet shape. In particular, in hot melt coating, the compound 12 is heated to melt the compound 12 to form a fluid, and then the coating is applied on the support substrate 13 such as a separator. Then, the long sheet-like green sheet 14 is formed on the support base material 13 by heat dissipation and solidifying. The temperature at which the compound 12 is heated and melted varies depending on the type and amount of the binder used, but is 50 to 300 ° C. However, the temperature needs to be higher than the flow start temperature of the binder to be used. When slurry coating is used, magnet powder and binder (additional additives may be added) are dispersed in a large amount of solvent, and the slurry is coated on a support substrate 13 such as a separator. Work. Thereafter, the long sheet-like green sheet 14 is formed on the support substrate 13 by drying and volatilizing the solvent.

  Here, as the coating method of the melted compound 12, it is preferable to use a method having excellent layer thickness controllability such as a slot die method and a calendar roll method. In particular, in order to achieve high thickness accuracy, a die method or comma coating method that is particularly excellent in layer thickness controllability (that is, a method capable of applying a high-accuracy thickness layer on the surface of a substrate). It is desirable to use For example, in the slot die method, coating is performed by extruding a heated compound 12 in a fluid state by a gear pump and inserting the compound 12 into a die. In the calendar roll method, a certain amount of the compound 12 is charged into the gap between the two heated rolls, and the compound 12 melted by the heat of the roll is applied onto the support base 13 while rotating the roll. Moreover, as the support base material 13, for example, a silicone-treated polyester film is used. Furthermore, it is preferable to sufficiently defoam the film so that bubbles do not remain in the spreading layer by using an antifoaming agent or performing heating vacuum defoaming. In addition, the green sheet is formed on the support substrate 13 by molding the compound 12 melted by extrusion molding or injection molding into a sheet shape and extruding the support substrate 13 instead of coating on the support substrate 13. 14 may be formed.

  Further, in the step of forming the green sheet 14 by the slot die method, it is desirable to actually measure the sheet thickness of the green sheet 14 after coating, and to feedback control the gap between the die 15 and the support base 13 based on the actually measured value. . Further, 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 fluctuation of ± 0.1% or less), and the fluctuation of the coating speed is reduced as much as possible (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 even more preferably within ± 1% with respect to the design value (for example, 1 mm). In the other calendar roll method, it is possible to control the transfer film thickness of the compound 12 onto the support base 13 by similarly controlling the calendar conditions based on the actually 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 less than 0.05 mm, the productivity must be reduced because multiple layers must be stacked.

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

  In addition, although the temperature and time at the time of heating the green sheet 14 change with kinds and quantity of a binder to be used, they are 100-250 degreeC and 0.1 to 60 minutes, for example. However, in order to soften the green sheet 14, it is necessary to set the glass transition point of the binder to be used or a temperature higher than the flow start temperature. As a heating method for heating the green sheet 14, for example, there are 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 to the in-plane direction and the length direction of the green sheet 14 softened by heating. The strength of the applied magnetic field is 5000 [Oe] to 150,000 [Oe], preferably 10,000 [Oe] to 120,000 [Oe]. As a result, the C axis (easy magnetization axis) of the magnet crystal included in the green sheet 14 is oriented in one direction. Note that the magnetic field may be applied in the in-plane direction and the width direction of the green sheet 14. Moreover, it is good also as a structure which applies a magnetic field with respect to the several green sheet 14 simultaneously.

  Furthermore, when applying a magnetic field to the green sheet 14, a process of applying a magnetic field simultaneously with the heating process may be performed, or the magnetic field may be applied after the heating process and before the green sheet 14 is solidified. It is good also as performing the process to apply. Moreover, it is good also as a structure which magnetic field orientates before the green sheet 14 apply | coated by hot-melt application solidifies. In that case, the heating step is not necessary.

  Next, the heating process and the magnetic field orientation process of the green sheet 14 will be described in more detail with reference to FIG. FIG. 9 is a schematic view showing a heating process and a magnetic field orientation process of the green sheet 14. In the example shown in FIG. 9, an example in which the magnetic field orientation process is performed simultaneously with the heating process will be described.

  As shown in FIG. 9, heating and magnetic field orientation on the green sheet 14 coated by the slot die method described above are performed on the long green sheet 14 in a state of being continuously conveyed by a roll. That is, an apparatus for performing heating and magnetic field orientation is disposed on the downstream side of the coating apparatus (die or the like), and is performed by a process continuous with the above-described coating process.

Specifically, the solenoid 25 is disposed on the downstream side of the die 15 and the coating roll 22 so that the transported support base material 13 and the green sheet 14 pass through the solenoid 25. Further, the hot plates 26 are arranged in a pair above and below the green sheet 14 in the solenoid 25. The green sheet 14 is heated by a pair of upper and lower hot plates 26 and an electric current is passed through the solenoid 25, so that the in-plane direction of the long green sheet 14 (that is, the sheet surface of the green sheet 14). A magnetic field in the longitudinal direction). Thereby, the continuously conveyed green sheet 14 is softened by heating, and a magnetic field is applied in the in-plane direction and the length direction (in the direction of arrow 27 in FIG. 9) of the softened green sheet 14. Appropriate and uniform magnetic field orientation can be realized. In particular, the surface of the green sheet 14 can be prevented from standing upright by setting the direction in which the magnetic field is applied to the in-plane direction.
Moreover, it is preferable that the heat dissipation and solidification of the green sheet 14 performed after the magnetic field orientation is performed in a transported state. Thereby, the manufacturing process can be made more efficient.

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

  Further, the magnetic field orientation can be set to a direction perpendicular to the surface of the green sheet 14. When the magnetic field orientation is performed in a direction perpendicular to the surface of the green sheet 14, for example, the magnetic field application device using a pole piece or the like is used. In the case where the magnetic field orientation direction is a direction perpendicular to the surface of the green sheet 14, it is preferable that the film is laminated on the surface on the opposite side of the green sheet 14 where the support base material 13 is laminated. Accordingly, it is possible to prevent the surface of the green sheet 14 from standing upside down.

  Further, instead of the heating method using 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 from a liquid material having high fluidity such as slurry by a general slot die method or doctor blade method without using hot melt molding, a magnetic field gradient is generated. When the green sheet 14 is carried in, the magnetic powder contained in the green sheet 14 is attracted toward the stronger magnetic field, so that the slurry forming the green sheet 14 is closer to the liquid, that is, the thickness of the green sheet 14 is uneven. May occur. On the other hand, when the compound 12 is molded into the green sheet 14 by hot melt molding as in the present invention, the viscosity near room temperature reaches several tens of thousands to several hundred thousand Pa · s, and the magnetism when passing through the magnetic field gradient is reached. There is no powder slippage. Furthermore, the viscosity of the binder is lowered by being transported and heated in a uniform magnetic field, and uniform C-axis orientation is possible only by the rotational torque in the uniform magnetic field.

  Further, when the green sheet 14 is molded by a liquid material having high fluidity such as a slurry containing an organic solvent by a general slot die method or doctor blade method without using hot melt molding, the thickness exceeds 1 mm. When an attempt is made to produce a sheet, foaming due to vaporization of the organic solvent contained in the slurry or the like at the time of drying becomes a problem. Further, if the drying time is prolonged to suppress foaming, the magnet powder is settled, and accordingly, the density distribution of the magnet powder is biased with respect to the direction of gravity, which causes warping after firing. Therefore, in the molding from the slurry, the upper limit value of the thickness is substantially regulated, so it is necessary to mold the 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 (calcination process), which causes a decrease in C-axis (easy magnetization axis) orientation, that is, residual magnetic flux density ( Br) decreases. On the other hand, when the compound 12 is molded into the green sheet 14 by hot melt molding as in the present invention, since it does not contain an organic solvent, even when a sheet having a thickness exceeding 1 mm is prepared, Concerns are resolved. And since the binder is in a sufficiently entangled state, there is no possibility of delamination in the debinding process.

  When applying a magnetic field to a plurality of green sheets 14 at the same time, for example, a plurality of (for example, six) green sheets 14 are continuously conveyed, and the stacked green sheets 14 pass through the solenoid 25. Configure to pass. As a result, productivity can be improved.

And after performing the magnetic field orientation of the green sheet 14 by the method shown in FIG. 9, the green sheet 14 is deformed by applying a load to the green sheet 14 and formed into a product shape. Note that the direction of the easy magnetization axis is displaced by the above deformation so as to be the direction of the easy magnetization axis required for the final product. As a result, the direction of the easy magnetization axis can be manipulated so that the easy magnetization axis converges in the direction along the focusing axis P as shown in FIG. Before the green sheet 14 is deformed, the final product shape and the shape taking into account the direction of the easy axis required for the final product (that is, the final product shape required when the green sheet 14 is transformed into the final product shape) are required. A shape in which the direction of the easy magnetization axis can be realized) is punched in advance and then deformed.
Moreover, when manufacturing a large-sized magnet, you may shape | mold by laminating | stacking the several green sheet 14 deform | transformed into the same shape, and mutually fixing with resin etc. For example, when manufacturing the permanent magnet 1 oriented so that the easy magnetization axis (C axis) is focused in one direction along the focusing axis P as shown in FIG. 3, the in-plane direction as shown in FIG. The green sheets 14 aligned in a magnetic field are curved and laminated so that the cross section in the thickness direction has an arc shape. As a result, the orientation as shown in FIG. 3 can be realized. The green sheet 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, a sheet-like green sheet 14 before performing magnetic field orientation cut to an appropriate length is wound around a cylindrical mold. Then, a magnetic field is applied to the green sheet 14 wound around the mold from one direction facing the surface of the green sheet 14. As a result, the easy magnetization axes of the magnet particles included in the green sheet 14 are aligned in parallel along the magnetic field application direction. Thereafter, the green sheet 14 is deformed by applying a load to form a product shape, and the direction of the easy magnetization axis is set so that the easy magnetization axis is focused in one direction along the focusing axis P by the deformation. to correct. For example, when a segment mold as shown in FIG. 3 is used as a product shape, the green sheet 14 that is curved along the mold is linear, and a load is applied from the left and right in the width direction. Shape. As a result, along with the deformation of the green sheet 14, the direction of the easy axis of magnetization of the green sheet 14 is also corrected, and an orientation as shown in FIG. 3 can be realized. Note that only one green sheet 14 may be deformed, or a plurality of green sheets 14 may be deformed in a stacked state.
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 be an arc shape, a fan shape, or a rectangular parallelepiped shape.

  Further, after forming a molded body corresponding to the 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 the molded body, and a magnetic field formed by passing a current through the solenoid coil is applied to the molded body. In the vicinity of the opening of the solenoid coil, a magnetic field in which the magnetic lines of force diffuse in the left-right direction is formed. Therefore, the compact is oriented so that the easy axis (C axis) is focused in one direction along the focusing axis P as shown in FIG. Moreover, you may orient using a permanent magnet or an electromagnet instead of a solenoid coil.

  Thereafter, the molded body 30 that has been molded and magnetically oriented is divided into a plurality of pieces using a cutting means such as a wire cut. And the sintered compact 31 is produced by sintering the molded object 30 divided | segmented into plurality. In addition, it is good also as a structure which divides | segments after the molded object 30 is sintered, and produces the sintered compact 31. FIG.

  Further, in the division of the compact 30, when the sintered bodies 31 are magnetized as described later, a magnetic field can be applied as parallel as possible to the orientation direction of the easy axis of each sintered body 31. That is, it is divided so that the orientation direction of the easy magnetization axis of each sintered body 31 is as linear as possible along one direction.

  Further, before sintering the compact 30, a non-oxidizing atmosphere (in particular, a hydrogen atmosphere in the present invention) pressurized to atmospheric pressure or a pressure higher or lower than atmospheric pressure (for example, 1.0 Pa or 1.0 MPa). Alternatively, it is desirable to perform the calcination treatment by maintaining the binder decomposition temperature for several hours to several tens of hours (for example, 5 hours) in a mixed gas atmosphere of hydrogen and an inert gas. In the case of performing in a hydrogen atmosphere, for example, the supply amount of hydrogen during calcination is set to 5 L / min. By performing the calcination treatment, an organic compound such as a binder can be decomposed into a monomer by a depolymerization reaction or the like and scattered to be removed. That is, so-called decarbonization that reduces the amount of carbon in the molded body 30 is performed. The calcining treatment is performed under the condition that the carbon content in the molded body 30 is 2000 ppm or less, more preferably 1000 ppm or less. As a result, the entire molded body 30 can be densely sintered by the subsequent sintering treatment, and a decrease in residual magnetic flux density and coercive force is suppressed. Moreover, when performing the pressurization conditions at the time of performing the calcining process mentioned above by the pressure higher than atmospheric pressure, it is desirable to set it as 15 MPa or less. In addition, if the pressurizing condition is a pressure higher than atmospheric pressure, more specifically 0.2 MPa or more, the effect of reducing the carbon amount can be expected.

  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 monomers are not generated, and products due to side reactions of the remaining binder components are not detected even in the analysis of the residues. Although it varies depending on the type of the binder, it is set to 200 ° C to 900 ° C, more preferably 400 ° C to 600 ° C (for example, 450 ° C).

  In the calcining process, it is preferable to reduce the rate of temperature rise compared to the case of performing general magnet sintering. Specifically, the temperature rising rate is set to 2 ° C./min or less (for example, 1.5 ° C./min). Therefore, when performing the calcination treatment, as shown in FIG. 11, the temperature is increased at a predetermined temperature increase rate of 2 ° C./min or less, and after reaching a preset temperature (binder decomposition temperature), The calcination treatment is performed by holding at the set temperature for several hours to several tens of hours. By reducing the temperature increase rate in the calcination treatment as described above, the carbon in the molded body 30 is not removed abruptly and is removed stepwise, thereby increasing the density of the sintered permanent magnet ( That is, it is possible to reduce the air gap in the permanent magnet. And if a temperature increase rate shall be 2 degrees C / min or less, the density of the permanent magnet after sintering can be made 95% or more, and a high magnet characteristic can be anticipated.

Moreover, you may perform a dehydrogenation process by hold | maintaining the molded object 30 calcined by the calcination process in a vacuum atmosphere continuously. 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 molded body 30 activated by the calcination treatment is reduced. As a result, even if the compact 30 that has been calcined by the calcining process is subsequently moved to the atmosphere, Nd is prevented from being combined with oxygen, and a decrease in residual magnetic flux density and coercive force is suppressed. To do. Moreover, the effect of returning the structure of the magnet crystals from NdH ₂ etc. to _Nd 2 _{Fe 14} B structure can be expected.

  On the other hand, as a sintering method of the molded body 30, pressureless sintering in a vacuum, uniaxial pressure sintering for sintering in a uniaxially pressurized state, and sintering in a state of being biaxially pressurized. There are two-axis pressure sintering, isotropic pressure sintering for sintering in an isotropically pressurized state, and the like. For example, uniaxial pressure sintering is used in which the compact 30 is sintered in a state in which it is pressed in a direction that is the same as the axial direction of the rotor 2 when the molded body 30 is disposed on the rotor 2 surface. Examples of pressure sintering include hot press sintering, hot isostatic pressing (HIP) sintering, ultra-high pressure synthetic sintering, gas pressure sintering, and discharge plasma (SPS) sintering. . However, it is preferable to use SPS sintering that can be uniaxially pressurized and sintered by current sintering. In addition, when sintering by SPS sintering, a pressurization value shall be 0.01MPa-100MPa, it shall be raised to 940 degreeC by 10 degreeC / min in a vacuum atmosphere of several Pa or less, and it shall hold | maintain for 5 minutes after that. Is preferred. Then, it is cooled and heat-treated again at 300 to 1000 ° C for 2 hours.

  Thereafter, the sintered bodies 31 obtained by dividing the molded body 30 are magnetized. For the magnetization of the sintered body 31, for example, a magnetizing coil, a magnetizing yoke, a condenser magnetizing power supply device, or the like is used. Then, in the magnetization step, magnetization is performed by applying an external magnetic field within a predetermined angle with respect to the approximate straight line L in the orientation direction of the easy axis of the sintered body 31 as shown in FIG. The “predetermined angle” can be appropriately set depending on the orientation direction of the easy axis of magnetization of the target permanent magnet 1, and is set to 20 degrees, for example. If the predetermined angle is set small, it is necessary to divide the molded body 30 into smaller and more sintered bodies 31. On the other hand, more efficient magnetization can be performed.

  Thereafter, the sintered bodies 31 magnetized by the above-described steps are joined to each other, thereby producing a permanent magnet 1 having a product shape (for example, a segment type shape) in which the plurality of sintered bodies 31 are coupled. The sintered body 31 is joined by an adhesive made of resin or the like (for example, a mixture of a resin and a solvent). Moreover, when joining with an adhesive agent, you may add a filler as an additive.

  The permanent magnet 1 is manufactured by the above process. Moreover, when manufacturing a generator and a motor using the manufactured permanent magnet 1, it manufactures by the manufacturing process shown in FIG.7 and FIG.8 in the accommodating part formed in the surface of the rotor 2 or the inside of the rotor 2. FIG. A plurality of permanent magnets 1 are arranged. Then, a generator and a motor are manufactured by assembling members other than the rotor 2 such as a shaft and a stator.

  The permanent magnet 1 joined with the magnetized sintered body 31 concentrates the magnetic flux inside the magnet from the center direction of the rotor 2 to the outer side (air gap side) (that is, the magnetic flux density on the magnet surface is increased). Be possible). In particular, when the permanent magnet 1 is disposed on the surface of the rotor 2 as shown in FIG. 6, it is possible to manufacture a generator or motor in which the polar anisotropic permanent magnet 1 is disposed on the surface of the rotor 2. Become.

As described above, in the permanent magnet 1 and the method for manufacturing the permanent magnet 1 according to the present embodiment, the compound 12 is generated by pulverizing the magnet raw material into magnet powder and mixing the pulverized magnet powder and the binder. . And the some sintered compact 31 is produced by performing shaping | molding with respect to the produced | generated compound 12, magnetic field orientation, and sintering. Next, the plurality of sintered bodies 31 are magnetized by applying a magnetic field in a direction based on the orientation direction of the easy axis of each sintered body 31, and the plurality of magnetized sintered bodies 31 are magnetized. Are bonded to each other to produce a bonded body in which a plurality of sintered bodies 31 are bonded, that is, a product-shaped permanent magnet 1. As a result, in the magnetizing step of the permanent magnet 1, even if the easy axis of the permanent magnet 1 is oriented in a complicated direction, the magnetic field can be applied as parallel as possible to the direction of the easy axis. . As a result, the permanent magnet 1 can be reliably magnetized (full magnetization) to the saturation point.
Further, in the magnetizing step of the permanent magnet 1, since the magnetic field is applied by applying a magnetic field within a predetermined angle with respect to the orientation direction of the easy axis of the sintered body 31, the same magnitude magnetic field is applied. Even so, the magnetic field contributing to the magnetization can be increased, and the magnetization can be performed more efficiently.
In particular, since the magnetic field is applied by applying a magnetic field within a predetermined angle (for example, 20 degrees) with respect to the approximate straight line of the orientation direction of the easy axis of the sintered body 31, the easy magnetization axis is oriented in a complicated curved shape. Even in the permanent magnet 1, the magnetic field can be applied as parallel as possible to the direction of the easy axis in the magnetization process of the permanent magnet 1. As a result, magnetization can be performed more efficiently, and the permanent magnet 1 can be surely magnetized (full magnetization) to the saturation point.
In addition, since the magnetic powder-oriented magnet powder compact is divided into a plurality of parts and sintered to form a plurality of sintered bodies 31 to be magnetized, the easy magnetization axis of the compact is oriented in a complicated direction. Even in such a case, it is possible to make the direction of the easy axis of each sintered body 31 to be magnetized as close to a straight line as possible. Further, by dividing the molded body before sintering, the division work can be easily performed.
On the other hand, it is possible to sinter a magnetic powder-oriented magnet powder compact and then divide it into a plurality of sintered bodies 31 to be magnetized. In that case, even if the compact is deformed or deformed due to sintering, it is possible to appropriately join the sintered bodies after magnetization.
Moreover, since the mixture of magnet powder and a binder is shape | molded, compared with the case where compacting etc. are used, a magnet particle does not rotate after an orientation and it becomes possible to improve an orientation degree. In addition, when magnetic field orientation is performed on a mixture with a binder, the number of current turns can be used, so that it is possible to ensure a large magnetic field strength when performing magnetic field orientation, and long-term magnetic field application with a static magnetic field. Therefore, it is possible to realize a high degree of orientation with little variation.
Furthermore, the realization of high orientation with little variation leads to a reduction in variation in shrinkage due to sintering. That is, the uniformity of the product shape after sintering can be ensured. As a result, it can be expected that the burden on the external processing after sintering is reduced and the stability of mass production is greatly improved.
In addition, a magnetic field is applied to the mixture of the magnet powder and the binder, and the direction of the easy magnetization axis is manipulated by transforming the mixture to which the magnetic field is applied into a molded body, thereby performing magnetic field orientation on the molded body. Therefore, it is possible to correct the orientation direction by deforming the mixture once magnetically oriented, and to perform magnetic field orientation of the compact. As a result, it is possible to perform a highly oriented orientation with little variation. Further, when the mixture is formed into a molded body, the orientation direction can be corrected simultaneously with the deformation to the molded body. As a result, the molding process and the orientation process of the permanent magnet can be performed in one process, and the productivity can be improved.
Moreover, since the sintered compact 31 is joined with an adhesive agent, it becomes possible to couple | bond the sintered compact 31 after magnetization appropriately. Moreover, even if the permanent magnet 1 is divided, it is possible to prevent the magnetic characteristics of the permanent magnet 1 to be finally produced from being deteriorated.
Further, since the easy magnetization axis is inclined and oriented so that the permanent magnet 1 is focused in one direction along the focusing axis P, the magnetic flux is appropriately concentrated on the surface on which the magnetic pole is formed after magnetization. It is possible to improve the maximum magnetic flux density and prevent the magnetic flux density from being varied. In particular, if permanent magnets are arranged on the rotor or stator of a rotating electric machine, the maximum magnetic flux density is improved by concentrating the magnetic flux on the air gap side, and the torque and power generation amount of the rotating electric machine on which the permanent magnets are arranged can be increased. As a result, torque ripple can be reduced.

In addition, this invention is not limited to the said Example, Of course, various improvement and deformation | transformation are possible within the range which does not deviate from the summary of this invention.
For example, the pulverization 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, in the above embodiment, the magnet raw material is pulverized by wet pulverization using a bead mill, but may be pulverized by dry pulverization using a jet mill. Moreover, as long as the atmosphere at the time of calcination is a non-oxidizing atmosphere, the atmosphere may be other than a hydrogen atmosphere (for example, a nitrogen atmosphere, a He atmosphere, or an Ar atmosphere). Moreover, you may abbreviate | omit a calcination process. In that case, decarbonization is performed during the sintering process.

  Moreover, in the said Example, although it is set as the structure which performs magnetic field orientation after shape | molding the mixture of magnet powder and a binder once to a sheet-shaped green molded object, the structure which performs magnetic field orientation after shape | molding in shapes other than a sheet shape. It is also good. For example, it may be molded into a block-shaped green molded body. The block-shaped green molded body oriented in the magnetic field is further processed to form a segment-shaped molded body 30.

  Moreover, in the said Example, although it is supposed that after dividing | segmenting after shape | molding once to the segment type | mold shaped molded object 30 which is a product shape, and forming the sintered compact 31, it does not shape | mold to a segment type | mold shape, but directly. You may comprise so that a mixture may be shape | molded to the sintered compact 31. FIG.

  In the above embodiment, the magnetic powder orientation is performed on the mixture of the magnet powder and the binder, and then the segment-shaped molded body 30 is molded. However, the segment-shaped molded body 30 is molded. After that, magnetic field orientation may be performed.

  Further, the orientation direction of the easy magnetization axis of the permanent magnet 1 is configured so that the easy magnetization axis is tilted and oriented so as to converge in one direction along the convergence axis P in the above embodiment. The orientation direction of the easy axis can be appropriately changed depending on the application of the permanent magnet 1. For example, it is good also as a structure which orientates in radial orientation or polar anisotropic orientation.

  Furthermore, in the said Example, although it is supposed that the segment-type permanent magnet used for a surface magnet type rotary electric machine is manufactured, the shape shape | molded according to a use can be changed variously. For example, it may be formed into a fan shape, a bow shape, a trapezoid shape, a rectangular parallelepiped shape, or the like. Thereby, it is also possible to manufacture a permanent magnet to be accommodated in a slot (accommodating portion) formed in the IPM motor or the like.

  Further, the present invention can also be applied to a rotating electrical machine in which the permanent magnet 1 is arranged on the stator side instead of the rotor side. Further, the present invention is not limited to an inner rotor type rotating electrical machine, and can also be applied to an outer rotor type rotating electrical machine. For example, when a permanent magnet is arranged in the stator of an outer rotor type rotating electrical machine, the beam is focused in a direction along the focusing axis P set in the radial direction of the stator and on the air gap side (outer direction with the rotor). In this way, the easy magnetization axis is inclined and oriented. As a result, the magnetic flux inside the magnet is concentrated from the central direction toward the air gap. Further, when a permanent magnet is disposed on the rotor of an outer rotor type rotating electrical machine, focusing is performed in a direction along the focusing axis P set in the radial direction of the rotor and on the air gap side (center direction with the stator). In this way, the easy magnetization axis is inclined and oriented. As a result, the magnetic flux inside the magnet concentrates from the outside direction to the air gap side. Further, the permanent magnet 1 can be applied to a dual-rotor type rotary electric machine or a linear motor in which permanent magnets are arranged in a plane. The permanent magnet 1 according to the present invention can be applied to various rotating electrical machines such as a generator and a magnetic speed reducer in addition to a motor.

  Furthermore, you may use a permanent magnet for uses other than a rotary electric machine. Even in such a case, since the maximum magnetic flux density of the permanent magnet according to the present invention is higher than that of the conventional permanent magnet, the performance of various products can be expected by using the permanent magnet according to the present invention.

  In the above embodiment, calcining is performed in a hydrogen atmosphere or a mixed gas atmosphere of hydrogen and an inert gas after molding the magnet powder. However, the magnet powder before molding is calcined and calcined. It is good also as manufacturing a permanent magnet by shape | molding the magnetic powder which is a body into a molded object, and performing sintering after that. With such a configuration, since the powdered magnet particles are calcined, the surface area of the magnet to be calcined is increased compared to the case of calcining the molded magnet particles. can do. That is, the amount of carbon in the calcined body can be reduced more reliably. However, in order to thermally decompose the binder by calcining, it is desirable to perform calcining after molding.

  In the present invention, the Nd—Fe—B system magnet has been described as an example, but other magnets (for example, a samarium system cobalt magnet, an alnico magnet, a ferrite magnet, etc.) may be used. Further, in the present invention, the Nd component is larger than the stoichiometric composition in the present invention, but it may be stoichiometric.

DESCRIPTION OF SYMBOLS 1 Permanent magnet 2 Rotor 3, 31 Sintered body 12 Compound 14 Green sheet 30 Molded body

Claims (18)

Crushing magnet raw material into magnet powder;
A step of obtaining a plurality of sintered bodies by performing molding, magnetic field orientation and sintering on the pulverized magnet powder;
Magnetizing the plurality of sintered bodies by applying a magnetic field in a direction based on the orientation direction of the easy axis of each sintered body;
A permanent magnet produced by joining the plurality of magnetized sintered bodies to each other to obtain a combined body in which the plurality of sintered bodies are combined.   2. The permanent magnet according to claim 1, wherein in the magnetizing step, the magnet is magnetized by applying a magnetic field within a predetermined angle with respect to the orientation direction of the easy axis of magnetization of the sintered body. The orientation direction of the easy axis of magnetization of the sintered body has a curved shape,
3. The permanent magnet according to claim 2, wherein in the magnetizing step, the permanent magnet is magnetized by applying a magnetic field within a predetermined angle with respect to an approximate straight line of an orientation direction of the easy axis of the sintered body.   The step of obtaining the plurality of sintered bodies includes dividing the magnetic powder oriented magnetic powder compact into a plurality of parts and then sintering the plurality of sintered bodies to obtain the plurality of sintered bodies. Item 4. The permanent magnet according to any one of Items 3 to 3.   The step of obtaining the plurality of sintered bodies includes obtaining a plurality of the sintered bodies by dividing the magnetic powder-oriented compact of the magnetic powder into a plurality of sintered bodies. Item 4. The permanent magnet according to any one of Items 3 to 3.   6. The permanent magnet according to claim 4, wherein in forming the formed body, a mixture in which the pulverized magnet powder and a binder are mixed is formed.   A magnetic field is applied to the mixture, and the orientation of the easy magnetization axis is manipulated by deforming the mixture to which the magnetic field is applied into the molded body, thereby performing magnetic field orientation on the molded body. The permanent magnet according to claim 6.   The permanent magnet according to claim 1, wherein the sintered body is bonded by an adhesive.   The permanent magnet according to any one of claims 1 to 8, wherein the coupling body is oriented with an easy magnetization axis inclined so as to be focused in one direction along the focusing axis. Crushing magnet raw material into magnet powder;
A step of obtaining a plurality of sintered bodies by performing molding, magnetic field orientation and sintering on the pulverized magnet powder;
Magnetizing the plurality of sintered bodies by applying a magnetic field in a direction based on the orientation direction of the easy axis of each sintered body;
A step of joining the plurality of magnetized sintered bodies together to obtain a combined body in which the plurality of sintered bodies are joined together.   The method of manufacturing a permanent magnet according to claim 10, wherein in the magnetizing step, the magnet is magnetized by applying a magnetic field within a predetermined angle with respect to the orientation direction of the easy axis of magnetization of the sintered body. The orientation direction of the easy axis of magnetization of the sintered body has a curved shape,
12. The permanent magnet according to claim 11, wherein in the magnetizing step, the permanent magnet is magnetized by applying a magnetic field within a predetermined angle with respect to an approximate straight line of an orientation direction of an easy axis of magnetization of the sintered body. Production method.   11. The step of obtaining the plurality of sintered bodies includes dividing the magnetic powder oriented magnetic powder compact into a plurality of parts and then sintering the plurality of sintered bodies to obtain a plurality of the sintered bodies. Item 13. A method for producing a permanent magnet according to any one of Items 12 to 13.   The step of obtaining the plurality of sintered bodies includes a plurality of the sintered bodies obtained by sintering the magnetic powder-oriented magnet powder compact and then dividing it into a plurality. Item 13. A method for producing a permanent magnet according to any one of Items 12 to 13.   The method for producing a permanent magnet according to claim 13 or 14, wherein in molding the molded body, a mixture in which the pulverized magnet powder and a binder are mixed is molded.   A magnetic field is applied to the mixture, and the orientation of the easy magnetization axis is manipulated by deforming the mixture to which the magnetic field is applied into the molded body, thereby performing magnetic field orientation on the molded body. The method for producing a permanent magnet according to claim 15.   The method for producing a permanent magnet according to any one of claims 10 to 16, wherein, in the step of obtaining the bonded body, the sintered body is bonded with an adhesive.   18. The permanent magnet according to claim 10, wherein the combined body is oriented with an easy magnetization axis inclined so as to be focused in one direction along the focusing axis. Method.

Images