JP7384016B2 - Rare earth permanent magnet manufacturing method and rare earth permanent magnet manufacturing device - Google Patents

Description

The present invention relates to a method for manufacturing a rare earth permanent magnet and an apparatus for manufacturing a rare earth permanent magnet.

An RTB permanent magnet containing a rare earth element R (such as neodymium), a transition metal element T (such as iron), and boron B has excellent magnetic properties. Residual magnetic flux density Br (remanent magnetization) and coercive force HcJ are generally used as indicators representing the magnetic properties of RTB-based permanent magnets.

The RTB permanent magnet is a nucleation type permanent magnet. By applying a magnetic field opposite to the magnetization direction to a nucleation type permanent magnet, nuclei of magnetization reversal are likely to occur near the grain boundaries of a large number of crystal grains (main phase grains) constituting the permanent magnet. This nucleus of magnetization reversal reduces the coercive force of the permanent magnet. Furthermore, the coercive force of the RTB permanent magnet decreases as the temperature increases. RTB permanent magnets used in motors, generators, etc. are required to have high coercive force even in high-temperature environments.

In order to improve the coercivity of the RTB permanent magnet, a heavy rare earth element such as dysprosium is added to the RTB permanent magnet. Addition of heavy rare earth elements improves the anisotropic magnetic field and makes it difficult to generate magnetization reversal nuclei, resulting in an increase in coercive force. In recent years, grain boundary diffusion methods have been used to obtain high coercivity with smaller amounts of heavy rare earth elements. In the grain boundary diffusion method, heavy rare earth elements are diffused along the grain boundaries from the magnet surface. As a result, the anisotropic magnetic field tends to locally increase in the vicinity of the grain boundaries, making it difficult for magnetization reversal nuclei to occur in the vicinity of the grain boundaries, thereby increasing the coercive force.

For example, in the method for manufacturing an RTB permanent magnet described in Patent Document 1 below, a paint containing a heavy rare earth element and an organic solvent is sprayed planarly onto the surface of the magnet from a nozzle. By heating the magnet to which paint is attached, the heavy rare earth elements in the paint diffuse into the magnet.

In the method for manufacturing an RTB permanent magnet described in Patent Document 2 below, a paint containing a heavy rare earth element and an organic solvent is sprayed from a nozzle onto the surface of the magnet in dots or lines. By heating the magnet to which the slurry is attached, the heavy rare earth elements in the paint diffuse into the magnet.

JP2015-65218A JP2018-78275A

In order to suppress variations in the composition and magnetic properties of the magnet, it is necessary to suppress variations in the amount of paint deposited per unit area on the surface of the magnet. If the amount of paint deposited per unit area on the surface of the magnet varies, it is difficult for the heavy rare earth elements in the paint to diffuse uniformly into the magnet. As a result, the composition and magnetic properties of the magnet vary, and the coercive force of the magnet does not improve sufficiently. For example, when paint is supplied from a nozzle to the surface of a magnet as in the methods described in Patent Documents 1 and 2 above, the nozzle is likely to become clogged with paint, and the amount of paint deposited per unit area of the magnet surface varies. easy. When the viscosity of the paint is reduced to prevent nozzle clogging, excess paint tends to drip from the nozzle onto the surface of the magnet, and the paint tends to flow from a predetermined position on the surface of the magnet. Therefore, even if the viscosity of the paint is reduced, it is difficult to sufficiently suppress variations in the amount of paint deposited per unit area.

The purpose of the present invention is to provide a method for manufacturing a rare earth permanent magnet, which suppresses variations in the amount of paint deposited per unit area on the surface of a magnet, in a step of attaching paint containing heavy rare earth elements to the surface of the magnet, and An object of the present invention is to provide a permanent magnet manufacturing device.

A method for manufacturing a rare earth permanent magnet according to one aspect of the present invention includes an adhesion step of adhering the heavy rare earth elements to the surface of the magnet, and heating the magnet to which the heavy rare earth elements are attached, thereby injecting the heavy rare earth elements into the magnet. The adhesion device used in the adhesion step has a plurality of columnar members, and the adhesion step includes applying a paint containing a heavy rare earth element to the tips of each of the plurality of columnar members. The method includes a first adhesion step of adhering the paint, and a second adhesion step of adhering the paint to the surface of the magnet by bringing the tips of the plurality of columnar members to which the paint is adhered into contact with the surface of the magnet.

The columnar member may expand and contract in the direction in which the columnar member extends, and may be contracted by bringing the tip end into contact with the surface of the magnet in the second attachment step.

The columnar member may include an elastic body, and due to the elasticity of the elastic body, the columnar member may elastically expand and contract in the direction in which the columnar member extends, and in the second attachment step, the tip portion is brought into contact with the surface of the magnet. This may cause the columnar member to shrink.

At least a portion of the surface of the magnet to which the paint adheres may be a curved surface.

An apparatus for manufacturing a rare earth permanent magnet according to one aspect of the present invention includes an adhesion device, the adhesion device has a plurality of columnar members, and a paint containing a heavy rare earth element is applied to the tip end of each of the plurality of columnar members. The paint adheres to the surface of the magnet by bringing the tips of the plurality of columnar members to which the paint has adhered into contact with the surface of the magnet.

In the above manufacturing apparatus, the columnar member may be expanded and contracted in the direction in which the columnar member extends, and the columnar member may be contracted by bringing the tip end into contact with the surface of the magnet.

In the above manufacturing apparatus, the columnar member may include an elastic body, and due to the elasticity of the elastic body, the columnar member may elastically expand and contract in the direction in which the columnar member extends, and the tip portion may be brought into contact with the surface of the magnet. This may cause the columnar member to shrink.

In the manufacturing apparatus described above, at least a portion of the surface of the magnet to which the paint adheres may be a curved surface.

According to the present invention, there is provided a method for manufacturing a rare earth permanent magnet, which suppresses variations in the amount of paint deposited per unit area of the magnet surface in a step of attaching paint containing a heavy rare earth element to the surface of the magnet, and A permanent magnet manufacturing apparatus is provided.

FIG. 1 is a perspective view of an attachment device included in a rare earth permanent magnet manufacturing apparatus according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing the internal structure of a columnar member included in the adhesion device shown in FIG. 1. FIG. 3 is a perspective view of a plate-shaped magnet before paint is applied. (a) in FIG. 4 is a perspective view of the arc segment type magnet before paint is attached, and (b) in FIG. 4 is a cross-sectional view of the magnet shown in (a) in FIG. It is. (a) in FIG. 5, (b) in FIG. 5, (c) in FIG. 5, and (d) in FIG. 5 outline the paint supply means used in the first adhesion step. (a) in FIG. 6, (b) in FIG. 6, and (c) in FIG. 6 outline the first attachment step. (a) in FIG. 7, (b) in FIG. 7, and (c) in FIG. 7 outline the second attachment process using the plate-shaped magnet shown in FIG. 3. (a) in FIG. 8, (b) in FIG. 8, and (c) in FIG. An overview of the adhesion process is shown. (a) in FIG. 9 is a schematic front view of the surface of a plate-shaped magnet to which paint is attached, and (b) in FIG. 9 is an example of a modification of the surface of the plate-shaped magnet to which paint is attached. FIG. (a) in FIG. 10 and (b) in FIG. 10 are schematic front views of a modified example of the surface of a plate-shaped magnet to which paint is adhered. (a) in FIG. 11, (b) in FIG. 11, (c) in FIG. 11, and (d) in FIG. 11 are perspective views of modified examples of the tip portion of the columnar member. FIG. 12 is a perspective view of a modified example of the tip end of the columnar member.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the drawings, like components are given like numbers. The present invention is not limited to the following embodiments. The "permanent magnet" described below means an RTB permanent magnet, which is a type of "rare earth permanent magnet."

[Preparation process of raw material alloy]
In the process of preparing a raw material alloy, an alloy material is produced from a metal raw material containing each element constituting a permanent magnet. The raw material alloy may be made by strip casting, book molding, or centrifugal casting. The metal raw material may be, for example, a rare earth element (element metal), an alloy containing a rare earth element, pure iron, ferroboron, or an alloy containing these. These metal raw materials are weighed so as to approximately match the composition of the desired permanent magnet. Two or more types of alloys having different compositions may be produced as the raw material alloy.

The raw material alloy contains at least a rare earth element R, a transition metal element T, and boron (B).

At least a portion of R contained in the raw material alloy is neodymium (Nd). The raw material alloy contains scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), promethium (Pm), samarium (Sm), europium (Eu), and gadolinium as other R. (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu). That's fine. Among the above rare earth elements, gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu) are It is a rare earth element. Among the above rare earth elements, the elements other than the heavy rare earth elements are light rare earth elements. The raw material alloy may contain Pr. The raw material alloy does not need to contain Pr. The raw material alloy may contain one or both of Tb and Dy. The raw material alloy may not contain one or both of Tb and Dy.

At least a portion of the transition metal element T contained in the raw material alloy is iron (Fe). T may be Fe and cobalt (Co). All T may be Fe. All T may be Fe and Co. The raw material alloy may further contain transition metal elements other than Fe and Co. T described below means only Fe or Fe and Co.

The raw material alloy may further contain other elements in addition to R, T and B. For example, the raw material alloy contains copper (Cu), gallium (Ga), aluminum (Al), zirconium (Zr), manganese (Mn), carbon (C), nitrogen (N), oxygen (O) as other elements. , calcium (Ca), nickel (Ni), silicon (Si), chlorine (Cl), sulfur (S), and fluorine (F).

[Crushing process]
In the grinding step, alloy powder may be prepared by grinding the raw material alloy described above in a non-oxidizing atmosphere. The raw material alloy may be ground in two steps: a coarse pulverization step and a fine pulverization step. In the coarse crushing step, for example, a crushing method such as a stamp mill, a jaw crusher, or a brown mill may be used. The coarse grinding step may be performed in an inert gas atmosphere. After storing hydrogen into the raw material alloy, the raw material alloy may be pulverized. That is, hydrogen storage pulverization may be performed as the coarse pulverization step. In the coarse pulverization step, the raw material alloy may be pulverized until its particle size becomes approximately several hundred μm. In the fine pulverization step that follows the coarse pulverization step, the raw material alloy that has undergone the coarse pulverization step may be further pulverized until its average particle size becomes several μm. In the pulverization step, for example, a jet mill may be used. The raw material alloy may be ground by only one stage grinding process. For example, only a pulverization step may be performed. When multiple types of raw material alloys are used, each raw material alloy may be ground separately and then mixed. The alloy powder may contain at least one lubricant (grinding aid) selected from the group consisting of fatty acids, fatty acid esters, and metal salts of fatty acids (metal soaps). In other words, the raw material alloy may be ground together with a grinding aid.

[Molding process]
In the molding step, by molding the above alloy powder in a magnetic field, a molded body containing the alloy powder oriented along the magnetic field may be obtained. For example, a compact may be obtained by pressing the alloy powder in a mold while applying a magnetic field to the alloy powder in the mold. The pressure exerted by the mold on the alloy powder may be 20 MPa or more and 300 MPa or less. The strength of the magnetic field applied to the alloy powder may be 950 kA/m or more and 1600 kA/m or less.

[Sintering process]
In the sintering step, a sintered body may be obtained by sintering the above-described molded body in a vacuum or an inert gas atmosphere. The sintering conditions may be appropriately set depending on the composition of the intended permanent magnet, the pulverization method of the raw material alloy, the particle size, etc. The sintering temperature may be, for example, 1000°C or more and 1200°C or less. The sintering time may be 1 hour or more and 20 hours or less.

[Aging treatment process]
In the aging step, the sintered body may be heated at a temperature lower than the sintering temperature. In the aging treatment step, the sintered body may be heated in a vacuum or an inert gas atmosphere. The diffusion step described below may also serve as an aging treatment step. In that case, an aging process separate from the diffusion process may not be performed. The aging treatment step may include a first aging treatment and a second aging treatment following the first aging treatment. In the first aging treatment, the sintered body may be heated at a temperature of 700°C or more and 900°C or less. The time for the first aging treatment may be 1 hour or more and 10 hours or less. In the second aging treatment, the sintered body may be heated at a temperature of 500°C or more and 700°C or less. The time for the second aging treatment may be 1 hour or more and 10 hours or less.

Through the above steps, a sintered body is obtained. The sintered body is a magnet used in the adhesion process and the diffusion process described later. Hereinafter, the magnet (sintered body) used in the adhesion process and the diffusion process will be referred to as a "magnet base material" to distinguish it from a finished product of a permanent magnet. The magnet substrate includes a plurality of main phase particles sintered together. The main phase particles contain at least Nd, Fe, and B. The main phase particles may include crystals of R ₂ T ₁₄ B, where at least some R may be Nd and at least some T may be Fe. Part or all of the main phase particles may consist only of R ₂ T ₁₄ B crystals (single crystal or polycrystal). R ₂ T ₁₄ B may be, for example, Nd ₂ Fe ₁₄ B. A portion of Nd in Nd ₂ Fe ₁₄ B may be substituted with at least one of Pr, Tb, and Dy. A part of Fe in Nd ₂ Fe ₁₄ B may be replaced with Co. The main phase particles may contain the above elements (elements that can be included in the raw material alloy) in addition to R, T, and B. The magnet base material includes grain boundaries formed between main phase grains. The magnet base material includes a plurality of grain boundary triple points as grain boundaries. A grain boundary triple point is a grain boundary surrounded by at least three main phase grains. The magnet substrate also includes a plurality of two-grain grain boundaries as grain boundaries. A two-grain grain boundary is a grain boundary located between two adjacent main phase grains. The grain boundaries may contain at least Nd, and the content of Nd in the grain boundaries may be greater than the content of Nd in the main phase particles. In other words, the grain boundaries may include the Nd-rich phase. The grain boundaries may contain at least one of Fe and B in addition to Nd.

The average particle diameter of the main phase particles is not particularly limited, but may be, for example, 1.0 μm or more and 10.0 μm or less. The total volume ratio of the main phase particles in the magnet base material is not particularly limited, but may be, for example, 75% by volume or more and less than 100% by volume.

The magnet base material used in the diffusion process may be processed in advance into a predetermined size and shape. Further, for the purpose of cleaning the surface of the magnet base material, pretreatment such as acid cleaning may be performed.

[Adhesion process]
The method for manufacturing a permanent magnet according to the present embodiment includes at least an adhesion step and a diffusion step in addition to the above steps. In the attachment step, heavy rare earth elements are attached to the surface of the magnet base material. The heavy rare earth element may be, for example, at least one element among Tb and Dy. In the diffusion step, the heavy rare earth element is diffused into the magnet base material by heating the magnet to which the heavy rare earth element is attached. Details of the diffusion process will be described later.

The permanent magnet manufacturing apparatus according to this embodiment includes an adhesion device used in the adhesion process. The attachment device has a plurality of columnar members. The attachment step includes a first attachment step and a second attachment step following the first attachment step. In the first attachment step, a paint containing a heavy rare earth element is attached to the tip of each of the plurality of columnar members. The paint may be a paste containing heavy rare earth elements, a binder and a solvent. Details of the composition of the paint will be described later. In the second adhesion step, the paint adheres to the surface of the magnet base by bringing the tips of the plurality of columnar members to which the paint is adhered into contact with the surface of the magnet base. Details of the deposition process and deposition apparatus are described below with reference to the figures.

As shown in FIG. 1, the adhesion device 20 includes a plurality of columnar members 10 and a plate-shaped fixing part 14. Each columnar member 10 is fixed to a fixed part 14. The lengths of each columnar member 10 are equal to each other. As shown in FIGS. 1 and 2, each columnar member 10 has a cylindrical portion 11, a columnar portion 12, and a tip portion 13 located at the tip of the columnar portion 12. The shape of the tube part 11 is a cylinder, and the shape of the column part 12 is a cylinder. The column part 12 is fitted into the cylinder part 11. The cylindrical portion 11 of each columnar member 10 passes through the fixed portion 14. Each columnar member 10 has a structure that prevents the columnar portion 12 from falling off from the cylindrical portion 11. The end surface of the tip portion 13 is a hemispherical convex surface. When the end surface of the tip portion 13 is a hemispherical convex surface, it is easy to suppress variations in the amount of paint deposited per unit area on the surface of the magnet base material. The number of columnar members 10 shown in FIG. 1 is 5×5. The directions D in which the plurality of columnar members 10 extend are approximately parallel to each other. The direction D in which the columnar member 10 extends may be referred to as the longitudinal direction D of the columnar member 10. The plurality of columnar members 10 are arranged in a grid pattern at regular intervals in a plane perpendicular to the direction D in which the columnar members 10 extend. That is, one straight line that belongs to the plane perpendicular to the direction D in which the columnar member 10 extends is represented as the first straight line, and a straight line that belongs to the plane perpendicular to the direction D in which the columnar member 10 extends and is perpendicular to the first straight line is Represented as a second straight line, five columnar members 10 are arranged on each of the five parallel first straight lines, and five columnar members 10 are arranged on each of the five parallel second straight lines, The interval between adjacent columnar members 10 on the first straight line is equal to the interval between adjacent columnar members 10 on the second straight line. When the plurality of columnar members 10 are arranged at equal intervals, it is easy to suppress variations in the amount of paint deposited per unit area on the surface of the magnet base material. By adjusting the spacing between the columnar members 10 in a plane perpendicular to the direction D in which the columnar members 10 extend, the amount of paint deposited per unit area on the surface of the magnet base material can be controlled. In other words, by adjusting the density of the columnar members 10 in a plane perpendicular to the direction D in which the columnar members 10 extend, it is possible to control the amount of paint deposited per unit area on the surface of the magnet base material. The tips 13 of all the columnar members 10 are arranged so as to be in contact with the same plane perpendicular to the direction D in which the columnar members 10 extend. As long as the columnar member 10 has mechanical strength capable of withstanding the adhesion process, the materials of the tube portion 11, column portion 12, and tip portion 13 are not limited. For example, the tube portion 11, the column portion 12, and the tip portion 13 may be made of metal.

As long as the adhesion device 20 includes a plurality of columnar members 10, the structure of the adhesion device 20 is not limited to the above structure. For example, the number and arrangement of columnar members 10 are not limited. The number and arrangement of the columnar members 10 are determined based on the thickness of the columnar members 10, the shape of the magnet base material, the area of the surface of the magnet base material, the location on the surface of the magnet base material where the paint needs to adhere, and the size of the magnet base material. It may be adjusted depending on the amount of paint applied per unit area of the surface. As long as the plurality of columnar members 10 do not interfere with each other, the directions D in which the plurality of columnar members 10 extend may not be parallel to each other. The tips 13 of all the columnar members 10 do not need to be arranged so as to be in contact with the same plane perpendicular to the direction D in which the columnar members 10 extend. For example, the tips 13 of all the columnar members 10 may be arranged so as to be in contact with the same curved surface (for example, a concave or convex surface) that extends along a direction perpendicular to the direction D in which the columnar members 10 extend. The structure of the columnar member 10 is not limited to the above structure. As will be described later, the shape of the end surface of the tip portion 13 is not limited to a hemispherical convex surface.

Since the columnar portion 12 is fitted into the cylindrical portion 11, the columnar portion 12 moves reversibly in the longitudinal direction D of the columnar member 10. That is, each columnar member 10 can freely expand and contract in the direction D in which the columnar member 10 extends. Therefore, in the second attachment step, each columnar member 10 can be shrunk to follow the shape of the surface of the magnet base material until the tip portions 13 of all the columnar members 10 reliably contact the surface of the magnet base material. In other words, even if the surface of the magnet base material is not flat, each columnar member 10 shrinks following the shape of the surface of the magnet base material, so that the tips 13 of all the columnar members 10 are on the surface of the magnet base material. Make sure to make contact. As a result, the paint adhering to the tip end 13 of each columnar member 10 tends to reliably adhere to the surface of the magnet base material, and it is easy to suppress variations in the amount of paint adhering per unit area of the surface of the magnet base material. The range of motion of the columnar part 12 in the longitudinal direction D of the columnar member 10 may be designed according to the shape of the surface of the magnet base material (for example, the curvature of the surface of the magnet base material).

Each columnar member 10 may include an elastic body. Due to the elasticity of this elastic body, the columnar member 10 may elastically expand and contract in the longitudinal direction D. For example, as shown in FIG. 2, each columnar member 10 has a spring 15 as an elastic body. One end of the spring 15 is fixed to the inner bottom of the cylindrical part 11, and the other end of the spring 15 is fixed to the end of the column part 12 inserted into the cylindrical part 11. In the second adhesion step, the columnar members 10 elastically contract following the surface of the magnet base material, so that the tip portion 13 of each columnar member 10 exerts an elastic force on the surface of the magnet base material. Therefore, compared to the case where each columnar member 10 does not include an elastic body, the tip portion 13 of each columnar member 10 can more easily come into contact with the surface of the magnet base material. As a result, the paint adhering to the tip end 13 of each columnar member 10 tends to reliably adhere to the surface of the magnet base material, and it is easy to suppress variations in the amount of paint adhering per unit area of the surface of the magnet base material. The elastic body is not limited to the spring 15. For example, the elastic body may be an elastomer (eg, rubber). The elastic body may be a sponge.

The shape of the magnet base material 2 is not limited. For example, as shown in FIG. 3, the magnet base material 2 may be a plate with a uniform thickness. The entire surface 2s of the magnet base material 2 to which the paint is applied in the second adhesion step may be flat. As shown in (a) in FIG. 4, the shape of the magnet base material 2 may be an arc segment. That is, the magnet base material 2 may be a rectangular plate curved in a certain direction. The entire surface 2s of the magnet base material 2 to which the paint is applied in the second adhesion step may be a convex curved surface. The cross section of the magnet base material 2 shown in (b) in FIG. 4 is parallel to the direction in which the magnet base material 2 curves, and perpendicular to the surface 2s of the magnet base material 2. r _о is the radius of curvature of the surface 2s. L _о is the length of the arc corresponding to the radius of curvature r _о . L _о may be rephrased as the width of the surface 2s in the direction in which the magnet base material 2 curves. θ _о is the opening angle of the surface 2s and is defined as L _о /r _о (unit: radian). r _i is the radius of curvature of the back surface (concave curved surface) of the front surface 2s. L _i is the length of the arc corresponding to the radius of curvature r _i . _Li may be rephrased as the width of the back surface of the front surface 2s in the direction in which the magnet base material 2 curves. θ _i is the opening angle of the back surface of the front surface 2s, and is defined as L _i /r _i (unit: radian). In (b) of FIG. 4, θ _о and θ _i match, but θ _о and θ _i do not have to match. In other words, the center of the circle corresponding to the radius of curvature r _о does not have to coincide with the center of the circle corresponding to the radius of curvature r _i . The number, position, and shape of the surfaces of the magnet base material 2 to which the paint is applied in the second adhesion step are not limited. For example, when the shape of the magnet base material 2 is a plate, by repeating the first adhesion process and the second adhesion process, the paint is applied not only to the flat surface 2s of the magnet base material 2 but also to the flat surface of the magnet base material 2. It may also adhere to the back side. When the shape of the magnet base material 2 is an arc segment, by repeating the first adhesion process and the second adhesion process, the paint is applied not only to the convex surface 2s of the magnet base material 2 but also to the concave surface of the magnet base material 2. It may also adhere to the back side of the

The shape of the magnet base material 2 is not limited to a plate or an arc segment. The surface 2s of the magnet base material 2 is not limited to a flat surface or a convex curved surface. For example, the surface 2s of the magnet base material 2 may be a concave curved surface. Only a part of the surface 2s of the magnet base material 2 may be a curved surface, and the other part may be a flat surface. It may have a shape.

(a) in FIG. 5, (b) in FIG. 5, (c) in FIG. 5, (d) in FIG. 5, (a) in FIG. 6, (b) in FIG. Part (c) in the figure shows an overview of the first attachment step. The permanent magnet manufacturing apparatus may include means for supplying the paint 4 to the tip end portion 13 of each columnar member 10. For example, an intaglio plate 6 is used as a means for supplying the paint 4 to the tip portion 13. The shape and dimensions of the recess 6a formed on the surface 6s of the intaglio 6 correspond to the shape and dimensions of the surface 2s of the magnet base material 2. As shown in FIGS. 5A and 5B, by moving the ink plate 3 along the surface 6s of the intaglio 6, the paint 4 is filled into the recesses 6a of the intaglio 6. Ru. As shown in (c) in FIG. 5 and (d) in FIG. 5, after the paint 4 is filled into the recess 6a of the intaglio 6, it adheres to the surface 6s of the intaglio 6 other than the recess 6a. The painted paint 4 is removed by the blade 5. The intaglio 6 may be made of metal such as steel. However, the material of the intaglio 6 is not limited.

The paint 4 collected from the surface 6s of the intaglio 6 by the blade 5 may be reused. Paint 4 contains expensive heavy rare earth elements. Therefore, by collecting and reusing the excess paint 4 in the first adhesion step, the manufacturing cost of the permanent magnet is reduced. When the paint 4 is directly supplied to the surface 2s of the magnet base material 2 by an inkjet method or a spray method, it is difficult to collect and reuse the paint 4 that has not adhered to the surface 2s of the magnet base material 2.

As shown in FIG. 6A, in the first adhesion step, the adhesion device 20 and the intaglio plate 6 are arranged so that the tip end 13 of each columnar member 10 faces the paint 4 in the recess 6a of the intaglio plate 6. Their positions are adjusted. As shown in FIG. 6B, in the first adhesion step, the tips 13 of all the columnar members 10 are pressed against the paint 4. As a result, the paint 4 adheres to the tips 13 of all the columnar members 10, as shown in FIG. 6(c). In the first attachment step, it is preferable to press the tip end 13 of each columnar member 10 against the bottom of the recess 6a to the extent that each columnar member 10 shrinks a little. When the tip 13 is pressed only against the paint 4 without pressing the tip 13 against the bottom of the recess 6a, the paint that adheres to the tip 13 of each columnar member 10 due to variations in the length of the columnar members 10, etc. The amount of 4 may vary. On the other hand, when the tip 13 of each columnar member 10 is pressed against the bottom of the recess 6a, the amount of paint 4 adhering to the tip 13 of each columnar member 10 is less likely to vary. When pressing the tip 13 of each columnar member 10 to the bottom of the recess 6a, the amount of paint 4 adhering to the tip 13 of each columnar member 10 can be reliably changed to the desired amount by changing the depth of the recess 6a. Easy to do.

The amount of paint 4 that adheres to the tip 13 depends on the shape and surface area of the end surface of the tip 13, the thickness of the paint 4 in the recess 6a of the intaglio 6, the distance that the tip 13 penetrates into the recess 6a, and the amount of paint 4 that adheres to the tip 13. The control may be based on the pressure exerted on the paint 4 in the recess 6a, the contact time between the tip 13 and the paint 4, the rate of rise of the adhesion device 20 away from the intaglio 6, the viscosity of the paint 4, etc. The thickness of the paint 4 within the recess 6a may be controlled based on the depth of the recess 6a. The viscosity of the paint 4 may be controlled based on the temperature and composition of the paint 4 (for example, the contents of heavy rare earth elements, binder, and solvent in the paint 4).

In the first adhesion step, the intaglio 6 may be fixed and the adhesion device 20 may be freely moved. Alternatively, the adhesion device 20 may be fixed and the intaglio 6 may be moved freely. Both the intaglio 6 and the applicator 20 may be freely movable.

The means for supplying the paint 4 to the tip 13 is not limited to the intaglio 6. For example, as a means for supplying the paint 4 to the tip portion 13, a letterpress or a planographic plate may be used. When a letterpress plate is used instead of the intaglio plate 6, the convex portions formed on the surface of the letterpress plate may have a predetermined pattern corresponding to the size and shape of the surface 2s of the magnet base material 2. A pattern made of the paint 4 may be formed by adhering the paint 4 to the surface of the convex portion of the plate. For example, the paint 4 may be applied to the surface of the convex portion of the relief plate. Alternatively, the surface of the convex portion of the letterpress may be brought into contact with the paint 4 contained in the liquid reservoir. If a lithographic plate is used instead of the intaglio plate 6, a pattern made of the paint 4 may be formed on the surface of the lithographic plate by screen printing. That is, the screen mask used for screen printing may have a predetermined pattern corresponding to the size and shape of the surface 2s of the magnet base material 2.

(a) in FIG. 7, (b) in FIG. 7, and (c) in FIG. 7 outline the second adhesion process using the plate-shaped magnet base material 2. As shown in (a) in FIG. 7, the permanent magnet manufacturing apparatus may further include a holding means 7 for holding the magnet base material 2. As the holding means 7, for example, a fixture in which a groove 7a is formed is used. By fitting the magnet base material 2 into the groove 7a of the fixture, the position of the magnet base material 2 is fixed. In the second adhesion step, the positions of the magnet base material 2 and the adhesion device 20 are adjusted so that the surface 2s (plane) of the magnet base material 2 faces the paint 4 adhered to the tip portion 13 of the columnar member 10. be done. In the second adhesion step, the adhesion device 20 may be fixed, and the holding means 7 for the magnet base material 2 may be freely moved. The holding means 7 for the magnet base material 2 may be fixed, and the adhesion device 20 may be freely moved. Both the adhesion device 20 and the holding means 7 of the magnet substrate 2 may be freely movable. The specific structure of the holding means 7 is not limited as long as it can hold the magnet base material 2.

As shown in FIG. 7B, in the second adhesion step, the end surface of each tip portion 13 to which the paint 4 is adhered is pressed against the surface 2s of the magnet base material 2. As a result, each columnar member 10 contracts, and the tips 13 of all the columnar members 10 come into contact with the surface 2s of the magnet base material 2 via the paint 4. Since the surface 2s of the magnet base material 2 is a flat surface, each of the columnar members 10a, 10b, 10c, 10d, and 10e shrinks to the same extent. As shown in (c) in FIG. 7, by separating each tip 13 from the surface 2s of the magnet base 2, the paint 4 adheres from each tip 13 to the surface 2s of the magnet base 2, and the paint A plurality of dots consisting of 4 are formed on the surface 2s of the magnet base material 2. Each columnar member 10 separated from the surface 2s of the magnet base material 2 stretches due to the weight of the columnar portion 12 or the elasticity of the elastic body (spring 15), and the length of each columnar member 10 returns to its original length. .

(a) in FIG. 8, (b) in FIG. 8, and (c) in FIG. 8 show an outline of the second adhesion process using the arc segment type magnet base material 2. As shown in (a) in FIG. 8, in the second adhesion step, the magnet is attached so that the surface 2s (curved surface) of the magnet base material 2 faces the paint 4 attached to the tip 13 of the columnar member 10. The positions of the base material 2 and the adhesion device 20 are adjusted. As shown in FIG. 8B, in the second adhesion step, the end surface of each tip 13 to which the paint 4 is adhered is pressed against the surface 2s of the magnet base material 2. As a result, each columnar member 10 shrinks to follow the shape of the surface 2s of the magnet base material 2, and the tips 13 of all the columnar members 10 come into contact with the surface 2s of the magnet base material 2 via the paint 4. Among the plurality of columnar members 10, the columnar member 10c located at the center contacts the most protruding portion of the surface 2s of the magnet base material 2. Therefore, the columnar member 10c located at the center contracts more than the other columnar members 10a, 10b, 10d, and 10e. As shown in (c) in FIG. 8, by separating each tip 13 from the surface 2s of the magnet base 2, the paint 4 adheres from each tip 13 to the surface 2s of the magnet base 2, and the paint A plurality of dots consisting of 4 are formed on the surface 2s of the magnet base material 2. Each columnar member 10 separated from the surface 2s of the magnet base material 2 stretches due to the weight of the columnar portion 12 or the elasticity of the elastic body (spring 15), and the length of each columnar member 10 returns to its original length. . In the second attachment step, all the columnar members 10 may be shrunk, or only some of the columnar members 10 may be shrunk.

(a) in FIG. 9 shows the arrangement of the paint 4 (dots) on the flat surface 2s of the plate-shaped magnet base material 2. That is, by the second adhesion process shown in (a) in FIG. 7, (b) in FIG. 7, and (c) in FIG. 7, the paint 4 (dot) is shown in (a) in FIG. It is arranged like this. As shown in FIGS. 1 and 9A, the arrangement of the paint 4 (dots) on the surface 2s of the magnet base material 2 matches the arrangement of the tip 13 in the adhesion device 20. As shown in (a) in FIG. 9, a plurality of dots made of the paint 4 are arranged in a grid pattern at equal intervals on the surface 2s of the magnet base material 2. In other words, a line segment parallel to one side of the surface 2s of the magnet base material 2 is represented as a first line segment L1, and a line segment perpendicular to the first line segment L1 on the surface 2s of the magnet base material 2 is represented as a second line segment. 5 dots (paint 4) are arranged on each of the five parallel first line segments L1, and five dots (paint 4) are arranged on each of the five parallel second line segments L2. The dots (paint 4) are lined up, and the interval between adjacent dots on the first line segment L1 is equal to the interval between adjacent dots (paint 4) on the second line segment L2. When a plurality of dots made of the paint 4 are arranged at regular intervals, it is easy to suppress variations in the amount of the paint 4 adhered per unit area of the surface 2s of the magnet base material 2. Adjacent dots (paint 4) may be in contact with each other. Adjacent dots (paint 4) may be integrated as long as variations in the amount of paint 4 deposited per unit area of surface 2s of magnet base material 2 are suppressed.

In the diffusion process (grain boundary diffusion method) described later, the heavy rare earth elements in the dots (paint 4) diffuse in all directions from the surface 2s of the magnet base material 2. That is, the heavy rare earth elements diffuse not only in a direction perpendicular to the surface 2s of the magnet base material 2 (depth direction) but also in a direction parallel to the surface 2s. For example, when the surface 2s of the magnet base material 2 is flat, the heavy rare earth element diffuses from the dots (paint 4) toward the inside of the magnet base material 2 in a substantially concentric hemispherical shape. On the other hand, the effective diffusion distance of the heavy rare earth element is limited to, for example, about 10 mm at most, although it depends on the amount of coating material 4 adhered and the implementation conditions of the diffusion process. By setting the distance d between the dots (paint 4) in consideration of the limited diffusion distance, the concentration distribution of the heavy rare earth element in the magnet base material 2 after the diffusion process can be made more uniform. The distance d between the dots (paint 4) may be, for example, 10 mm or less, 5 mm or less, 2 mm or less, or 1 mm or less. In order to make the concentration distribution of heavy rare earth elements more uniform in the magnet base material 2 after the diffusion process, the distance of the dots (paint 4) from the end of the magnet base material 2 is, for example, 5 mm or less, 2.5 mm or less. , 1 mm or less, or 0 mm. As mentioned above, by controlling the amount of paint 4 deposited per unit area and setting the distance d between dots in consideration of the diffusion distance of heavy rare earth elements, the composition of the magnet base material 2 after the diffusion process can be controlled. Variations are easily suppressed.

The arrangement of the dots (paint 4) on the surface 2s of the magnet base material 2 is not limited to the arrangement shown in (a) in FIG. The arrangement of the dots (paint 4) on the surface 2s of the magnet base material 2 is designed and determined according to the characteristics required of the magnet and the dimensions and shape of the magnet base material. (b) in FIG. 9 shows an example of a change in the arrangement of the paint 4 (dots) on the flat surface 2s of the plate-shaped magnet base material 2. As shown in FIG. 9B, another dot (paint 4a) may be placed at the center of the four dots (paint 4). This arrangement of dots increases the density of dots on the surface 2s of the magnet base material 2. That is, the number of dots (paint 4) per unit area of the surface 2s of the magnet base material 2 increases. The arrangement of the dots (paint 4) on the surface 2s of the magnet base material 2 matches the arrangement of the tip portion 13 in the adhesion device 20. Therefore, by changing the arrangement of the tip portion 13 in the adhesion device 20, the density of dots (paint 4) on the surface 2s of the magnet base material 2 may be adjusted.

As shown in (a) in FIG. 8, (b) in FIG. 8, and (c) in FIG. 8, the surface 2s of the magnet base material 2 is a curved surface (convex surface), and When is constant, the density of dots (paint 4) at the ends of the surface 2s of the magnet base 2 tends to be lower than the density of dots (paint 4) at the center of the surface 2s of the magnet base 2. In order to make the density of dots (paint 4) more uniform on the curved surface, the spacing between the columnar members 10 may be gradually changed according to the change in the slope of the surface 2s of the magnet base material 2. However, even if the surface 2s of the magnet base material 2 is a curved surface, according to the present embodiment, compared to conventional methods (inkjet method, etc.), the surface area 2s of the magnet base material 2 has a Variations in the amount of paint 4 deposited can be suppressed.

The amount of paint 4 that adheres to the surface 2s of magnet base material 2 in the second adhesion process may be controlled based on the amount of paint 4 that adheres to tip portion 13 in the first adhesion process. In order to control the amount of paint 4 that adheres to the magnet base material 2 from each tip part 13 in the second adhesion step, the shape and surface area of the end face of the tip part 13, and the effect that the tip part 13 has on the surface 2s of the magnet base material 2 are determined. The pressure, the contact time between the tip 13 and the magnet substrate 2, the rate of rise of the deposition device 20 away from the magnet substrate 2, the viscosity of the paint 4, etc. may be controlled. The viscosity of the paint 4 may be controlled based on the temperature and composition of the paint 4. The thickness of the coating material 4 adhering to the surface 2s of the magnet base material 2 may be, for example, 1 μm or more and 200 μm or less after drying. The thickness of the magnet base material 2 is much larger than the thickness of the paint 4. The thickness of the magnet base material 2 may be, for example, 0.5 mm or more and 25 mm or less. As long as the amount of paint 4 adhered per unit area of the surface 2s of the magnet base material 2 does not vary, after each columnar member 10 is separated from the surface 2s of the magnet base material 2, a portion of the paint 4 will be attached to the tip portion 13. may remain.

Since the tip 13 can easily come into contact with the surface 2s of the magnet base 2, at least the portion of the tip 13 that comes into contact with the surface 2s of the magnet base 2 may be made of an elastomer (for example, rubber). The elastomer may be, for example, a silicone rubber. If at least the portion of the tip portion 13 that contacts the surface 2s of the magnet base material 2 is made of silicone rubber, the paint 4 is likely to peel off from the tip portion 13 in the second adhesion step, and the paint 4 will not adhere to the magnet base material 2. easily adheres to the surface 2s. At least a portion of the tip portion 13 that contacts the surface 2s of the magnet base material 2 may be made of a fluororesin such as polytetrafluoroethylene (PTFE). In that case, in the second adhesion step, the paint 4 is likely to peel off from the tip portion 13, and the paint 4 is likely to adhere to the surface 2s of the magnet base material 2. The material of the tip portion 13 may be appropriately selected based on the following matters.
Shape of magnet base material 2.
Ease of adhesion of paint 4 to tip portion 13 in the first adhesion step.
Ease of adhesion of paint 4 from tip portion 13 to magnet base material 2 in the second adhesion step.
Durability of tip 13.
The ease with which the paint 4 adheres from the tip 13 to the magnet base material 2 varies depending on the affinity between the solvent in the paint 4 and the end surface of the tip 13. The material of the end surface of the portion 13 may be selected.

In this embodiment, the tip portion 13 of each columnar member 10 to which the paint 4 is attached directly contacts the surface 2s of the magnet base material 2, so that the paint 4 is placed at a predetermined position on the surface 2s of the magnet base material 2. Adheres securely. As a result, the amount of paint 4 deposited per unit area of the surface 2s of the magnet base material 2 is controlled to be uniform. Since the amount of coating material 4 deposited per unit area is controlled uniformly, the heavy rare earth elements in the coating material 4 are uniformly diffused into the magnet base material 2 during the diffusion process, suppressing variations in the composition and magnetic properties of the permanent magnet. The coercive force of the permanent magnet increases. The amount of coating material 4 deposited per unit area of the surface 2s of the magnet base material 2 may be expressed as the mass of the coating material 4 per unit area of the surface 2s of the magnet base material 2.

If the paint 4 is sprayed from a nozzle onto the surface 2s of the magnet base 2, the nozzle is likely to be clogged with the paint 4, and the paint 4 may not be supplied to a predetermined position on the surface 2s of the magnet base 2. Therefore, in the case of a method using a nozzle (for example, an inkjet method), the amount of paint deposited per unit area of the surface 2s of the magnet base material 2 tends to vary. When the viscosity of the paint 4 is reduced to suppress clogging of the nozzle, excess paint 4 tends to drip from the nozzle onto the surface 2s of the magnet base 2, and the paint 4 does not stay at a predetermined position on the surface 2s of the magnet base 2. Easy to flow from. In particular, when the surface 2s of the magnet base material 2 is a curved surface, the paint 4 tends to flow on the surface 2s due to gravity. Even when the paint 4 adhering to the surface 2s of the magnet base material 2 is dried by heating, the viscosity of the paint 4 tends to decrease as the temperature rises, and the paint 4 may flow during drying. For these reasons, even if the viscosity of the paint 4 is reduced and nozzle clogging is suppressed, variations in the amount of paint 4 adhered to the surface 2s of the magnet base material 2 can be suppressed by the method using a nozzle. That is difficult. Even when the paint 4 is directly sprayed onto the surface 2s of the magnet base material 2 by a spray method, the viscosity of the paint 4 is low, and the paint 4 easily flows on the surface 2s of the magnet base material 2. The amount of paint 4 deposited per unit area tends to vary. Also when the magnet base material 2 is immersed in the paint 4, the paint 4 tends to flow on the surface 2s of the magnet base material 2, and the amount of paint 4 attached per unit area of the surface 2s of the magnet base material 2 tends to vary. .

On the other hand, in the second step of this embodiment, no nozzle is used in the first place, so the above-mentioned problem caused by nozzle clogging does not occur. Further, in this embodiment, there is no need to reduce the viscosity of the paint 4 in order to suppress nozzle clogging. Therefore, in this embodiment, the above-mentioned problem caused by the low viscosity of the paint 4 is unlikely to occur, and the viscosity of the paint 4 used in the first step can be adjusted over a wide range. Further, according to the present embodiment, by using the paint 4 whose viscosity is appropriately adjusted, the paint 4 can flow on the surface 2s of the magnet base 2 even if the surface 2s of the magnet base 2 is a curved surface. is suppressed, the amount of paint 4 deposited per unit area of the surface 2s of the magnet base material 2 is controlled uniformly, and changes in the shape of the paint 4 (dots) on the surface 2s of the magnet base material 2 are also suppressed.

In the inkjet method, fine droplets of the paint 4 are directly supplied to the surface 2s of the magnet base material 2 by a non-contact nozzle using a discharge element (air actuator or electromagnetic solenoid actuator). The amount of paint 4 discharged from the nozzle per unit time is small. Therefore, in the case of the inkjet method, it takes time to form a plurality of dots made of a sufficient amount of paint 4 on the surface 2s of the magnet base material 2. In other words, the coating speed of the paint 4 in the inkjet method is slow. On the other hand, in the second adhesion step of this embodiment, a plurality of dots made of the paint 4 are instantaneously formed on the surface 2s of the magnet base material 2. As a result, manufacturing time for permanent magnets is reduced. For the same purpose, the first deposition step and the second deposition step may be performed simultaneously and in parallel using a plurality of deposition devices 20.

The inkjet method requires a complicated control mechanism to control the amount of paint 4 ejected and the position of the nozzle. Therefore, the manufacturing equipment used in the inkjet method is expensive. On the other hand, the permanent magnet manufacturing apparatus according to this embodiment does not require a complicated control mechanism such as the inkjet method. Therefore, the permanent magnet manufacturing apparatus according to this embodiment is cheaper than the manufacturing apparatus used for the inkjet method.

Depending on the shape or use of the magnet, it may be necessary to intentionally diffuse the heavy rare earth elements into the magnet base material 2 non-uniformly. This is because, depending on the shape or purpose of the magnet, the magnetization of the magnet tends to be locally reversed, and areas where the magnetization is easily reversed require a higher coercive force than other parts. This is because it is necessary to contain rare earth elements. For example, in a region where the thickness in the magnetization direction is smaller than other regions, the demagnetizing field tends to be locally strong. As a result, magnetization reversal is likely to occur in areas where the thickness in the magnetization direction is small. Additionally, depending on the application of the magnet, eddy currents are generated within the magnet due to changes in the external magnetic field. The coercive force of the magnet may locally decrease due to temperature rise due to Joule heat associated with eddy currents. For the above reasons, the concentration distribution of the heavy rare earth elements in the magnet may be controlled by reliably diffusing the heavy rare earth elements to areas where magnetization is likely to be reversed. Therefore, in the second adhesion step, the paint 4 may be applied only to a specific portion of the surface 2s of the magnet base material 2. That is, the amount of paint deposited per unit area on a specific portion of the surface 2s of the magnet base material 2 may be controlled to be uniform. For example, dots (paint 4) may be formed only on a specific portion of the surface 2s of the magnet base material 2 by changing the arrangement of the tip portion 13 in the adhesion device 20. As a result, in the diffusion step, the heavy rare earth element can be reliably diffused into a region where magnetization reversal is likely to occur (a region where demagnetization is likely to occur). For example, as shown in (a) in FIG. 10, a plurality of dots (paint 4) may be formed at equal intervals along the outer edge of the surface 2s of the magnet base material 2. In order to arrange the dots (paint 4) as shown in FIG. 10(a), a deposition device 20 including a plurality of columnar members 10 arranged annularly at equal intervals may be used. As shown in FIG. 10(b), a plurality of dots (paint 4) may be formed at equal intervals along a pair of opposing sides on the surface 2s of the magnet base material 2. In order to arrange the dots (paint 4) as shown in (b) in FIG. 10, an adhesion device 20 comprising a plurality of columnar members 10 arranged at equal intervals on two parallel line segments is used. good.

By repeating the first adhesion process and the second adhesion process, the amount of paint 4 adhesion per unit area of the surface 2s of the magnet base material 2 may be controlled. By repeating the first adhesion process and the second adhesion process using a plurality of adhesion devices 20 that differ in the number, structure, or arrangement of columnar members 10, the amount of coating material 4 adhered per unit area of the surface 2s of the magnet base material 2 can be reduced. may be controlled. By repeating the first adhesion process and the second adhesion process using a plurality of adhesion devices 20 that differ in the number, structure, or arrangement of the columnar members 10, paint per unit area is applied to each portion of the surface 2s of the magnet base material 2. The adhesion amount of No. 4 may be changed. By repeating such a first attachment step and a second attachment step, the heavy rare earth element can be reliably diffused to a region where magnetization is easily reversed, and the concentration distribution of the heavy rare earth element in the magnet can be controlled.

As mentioned above, the paint 4 may be a paste containing a heavy rare earth element, a binder, and a solvent. The "diffusion material" described below means a chemical substance containing at least a heavy rare earth element. The diffusive material may be particles or powder. The particle size of the diffusion material may be adjusted by means similar to the coarse pulverization process and the fine pulverization process described above. The median diameter D50 of the diffusion material may be, for example, 0.5 μm or more and 15 μm or less. Paint 4 may be prepared by the following method.

The lacquer is prepared by stirring and mixing the binder and solvent in a predetermined ratio to dissolve the binder. The binder may be a thermoplastic resin. The binder may be, for example, at least one compound selected from the group consisting of ethyl cellulose resin, polyvinyl butyral resin, polyvinyl acetal resin, and acrylic resin. Multiple types of binders may be used. The solvent is not limited as long as it is a liquid that dissolves the binder. The solvent may be an organic solvent. The solvent may be, for example, a compound consisting of ethanol, butanol, octanol, methyl ethyl ketone, xylene, butyl carbitol, terpineol, and dihydroterpineol. Multiple types of solvents may be used. After adding the diffusing material to the lacquer, these are mixed. If desired, one or both of plasticizers and dispersants may also be added to the lacquer. This is followed by a dispersion treatment of the mixture of diffuser and lacquer. The dispersion treatment means may be a rotation-revolution mixer, a three-roll mixer, a high-pressure homogenizer, or an ultrasonic homogenizer. Distributed processing may be performed using multiple means.

The diffusion material may be, for example, a simple heavy rare earth element, an alloy containing a heavy rare earth element, or a compound containing a heavy rare earth element. The compound containing a heavy rare earth element may be, for example, at least one selected from the group consisting of hydrides, fluorides, and oxides. The heavy rare earth element may be one or both of Tb and Dy. The alloy containing the heavy rare earth element may be at least one selected from the group consisting of an alloy consisting of Tb and Fe, an alloy consisting of Dy and Fe, and an alloy consisting of Tb, Dy, and Fe. Examples of heavy rare earth element hydrides include TbH ₂ , TbH ₃ , alloy hydrides consisting of Tb and Fe, DyH ₂ , DyH ₃ , alloy hydrides consisting of Dy and Fe, and Tb, Dy, and Fe. It may be at least one selected from the group consisting of hydrides of alloys consisting of. The diffusion material may further contain at least one element selected from the group consisting of Nd, Pr, and Cu. For example, the diffusion material includes simple Nd, simple Pr, alloys containing Nd and Pr, hydrides of NdH ₂ , NdH ₃ , PrH ₂ , PrH ₃ , alloys containing Nd and Pr, simple Cu, and Cu. It may further contain at least one selected from the group consisting of alloy, CuH, Cu ₂ O, and CuO.

By the method described above, the paint 4 containing the diffusion material, binder, and solvent is prepared. The content of the diffusion material in the paint 4 depends on the thickness of the magnet base material 2, the designed composition of the permanent magnet, the desired viscosity of the paint 4, the adhesion of the paint 4 to the tip 13 of the columnar member 10, and the magnet base. It may be adjusted as appropriate in consideration of the adhesion of the paint 4 to the material 2. The content of the binder in the paint 4 may be appropriately adjusted in consideration of the desired viscosity of the paint 4 and the adhesion strength of the coating film obtained by drying the paint 4 to the magnet base material 2. Filtration of the paint 4 may remove coarse particles and aggregates from the paint 4. The content of the diffusion material in the paint 4 may be, for example, 40% by mass or more and 85% by mass or less. The content of the binder in the paint 4 may be, for example, 1% by mass or more and 15% by mass or less. The content of the solvent in the paint 4 may be, for example, 10% by mass or more and 59% by mass or less.

The method for manufacturing a permanent magnet may further include a drying step for removing at least a portion of the solvent contained in the paint 4 adhering to the magnet base material 2 after the adhesion step and before the diffusion step. When the adhesion process is repeated multiple times, a drying process may be performed after each adhesion process. A single drying step may be performed after multiple deposition steps.

[Diffusion process]
In the diffusion step, the magnet base material 2 to which the paint 4 containing heavy rare earth elements (diffusion material) is attached is heated. By heating the paint 4 and the magnet base material 2 in the diffusion process, the heavy rare earth elements in the paint 4 diffuse from the surface of the magnet base material 2 into the inside of the magnet base material 2 . Inside the magnet base material 2, the heavy rare earth elements diffuse into the vicinity of the surfaces of the main phase particles via grain boundaries. Near the surface of the main phase particles, some light rare earth elements (such as Nd) are replaced with heavy rare earth elements. As the heavy rare earth elements are localized near the surface of the main phase grains and at the grain boundaries, the anisotropic magnetic field becomes locally large near the grain boundaries, making it difficult for magnetization reversal nuclei to occur near the grain boundaries. . As a result, the coercive force of the permanent magnet increases.

In the diffusion step, the paint 4 and the magnet substrate 2 may be heated in vacuum or in an inert gas. The inert gas may be a rare gas such as argon (Ar). In the diffusion step, the coating material 4 and the magnet base material 2 may be heated at a temperature (diffusion temperature) of 800° C. or higher and 950° C. or lower. The time during which the coating material 4 and the magnet base material 2 are heated at the above diffusion temperature may be 1 hour or more and 50 hours or less. Before heating the paint 4 and the magnet base material 2 at the above diffusion temperature, the binder in the paint 4 may be burned out by heating the paint 4 at a temperature lower than the diffusion temperature. That is, a binder removal process may be performed as a pre-diffusion step.

[Heat treatment process]
The magnet base material 2 that has undergone the diffusion process may be used as a finished permanent magnet. A heat treatment step may be performed after the diffusion step. In the heat treatment step, the magnet base material 2 may be heated in a vacuum or an inert gas atmosphere. In the heat treatment step, the magnet base material 2 may be heated at 450°C or higher and 600°C or lower. In the heat treatment step, the magnet base material 2 may be heated at the above temperature for 1 hour or more and 10 hours or less. The heat treatment process tends to improve the magnetic properties (especially coercive force) of the permanent magnet.

After the diffusion step or the heat treatment step, the dimensions and shape of the magnet base material 2 may be adjusted by processing methods such as cutting and polishing.

By the above method, a permanent magnet is completed.

The composition of the magnet base material and the permanent magnet can be determined by, for example, energy dispersive X-ray spectroscopy (EDS), X-ray fluorescence (XRF) analysis, high-frequency inductively coupled plasma (ICP) emission spectrometry, inert gas melting. It may be identified by analytical methods such as non-dispersive infrared absorption, combustion in a stream of oxygen-infrared absorption, and inert gas melting-thermal conductivity.

The dimensions and shape of the permanent magnet vary depending on the use of the permanent magnet and are not particularly limited. The shape of the permanent magnet may be, for example, a rectangular parallelepiped, a cube, a rectangle (plate), a polygonal prism, a fan, an annular sector, a sphere, a disk, a cylinder, a ring, or a capsule. The cross-sectional shape of the permanent magnet may be, for example, a polygon, an arc (chord), a bow, an arch, or a circle. The dimensions and shape of the magnet base material 2 may also be similar to those of the permanent magnet.

Permanent magnets are used in hybrid cars, electric cars, hard disk drives, magnetic resonance imaging (MRI), smartphones, digital cameras, flat-screen TVs, scanners, air conditioners, heat pumps, refrigerators, vacuum cleaners, washer/dryers, elevators, wind power generators, etc. may be used in various fields. Permanent magnets may be used as materials for constructing motors, generators or actuators.

The present invention is not limited to the embodiments described above. Various modifications of the present invention are possible without departing from the spirit of the present invention, and these modifications are also included in the present invention.

For example, each columnar member 10 does not need to freely expand and contract in the direction D in which the columnar member 10 extends. When the surface 2s of the magnet base material 2 is a flat surface, in the second adhesion step, each columnar member 10 does not expand or contract, and the paint attached to the tip 13 of each columnar member 10 adheres to the surface of the magnet base material. can do. However, even if the surface 2s of the magnet base material 2 is a flat surface, it is preferable that each columnar member 10 freely expand and contract in the direction D in which the columnar member 10 extends.

The shape of the tip portion 13 is not limited to the shape described above. By changing the shape of the tip 13, the amount of paint 4 that adheres to the tip 13 in the first adhesion step may be changed. By changing the shape of the tip portion 13, the amount of paint 4 that adheres to the magnet base material 2 in the second adhesion step may be changed. For example, as shown in FIG. 11(a), the entire tip portion 13 may be a cylinder, and the end surface of the tip portion 13 may be a flat circle. As shown in FIG. 11(b), the entire tip portion 13 may be a cylinder, and the end surface of the tip portion 13 may be a concave curved surface. As shown in FIG. 11(c), the tip portion 13 may be a cylinder or a cone continuous to the cylinder. As shown in FIG. 11(d), four sharp convex portions may be formed on the cylindrical tip portion 13. In other words, two perpendicular V-shaped grooves may be formed at the end of the cylindrical tip 13. As shown in FIG. 12, four convex portions that fit into the plus (+) type grooves may be formed on the cylindrical tip portion 13. In other words, four grooves may be formed in the cylindrical tip 13 like a cross slot screwdriver. The entire tip portion 13 may be a polygonal prism, and the end surface of the tip portion 13 may be polygonal. For example, the end surface of the tip portion 13 may be triangular (e.g., regular triangle), quadrilateral (e.g., square), or hexagonal (e.g., regular hexagon). One or more grooves may be formed in the end faces of these polygons.

The magnet substrate used in the adhesion and diffusion steps may be a hot worked magnet rather than a sintered body. The hot-worked magnet may be manufactured by the following manufacturing method.

The raw material for the hot-worked magnet may be the same alloy as the raw material alloy used for producing the sintered body. By melting this alloy and then rapidly cooling it, a ribbon made of the alloy can be obtained. By crushing the ribbon, flaky alloy powder is obtained. A compact is obtained by cold pressing (molding at room temperature) the alloy powder. After preheating the compact, an isotropic magnet is obtained by hot pressing the compact. An anisotropic magnet is obtained by hot plastic working of an isotropic magnet. By aging the anisotropic magnet, a magnet base material made of a hot-worked magnet is obtained. A magnet base material made of a hot-worked magnet includes a large number of main phase particles bonded to each other, similar to the above-mentioned sintered body.

Rare earth permanent magnets are not limited to RTB permanent magnets. The rare earth permanent magnet (or magnet base material) may be, for example, a samarium cobalt magnet or a praseodymium magnet. The main phase of the rare earth permanent magnet (or magnet base material) may be, for example, SmCo ₅ , Sm ₂ Co ₁₇ , or PrCo ₅ .

According to the method for producing a rare earth permanent magnet according to the present invention, a rare earth permanent magnet can be obtained, which is applied to a motor or generator mounted on a hybrid vehicle or an electric vehicle, for example.

2... Magnet base material (magnet), 2s... Surface of magnet base material (magnet), 3... Ink plate, 4, 4a... Paint containing heavy rare earth elements, 5... Blade, 6... Intaglio, 6a... Recessed part of intaglio, 6s... Surface of intaglio, 7... Holding means (fixing tool) for magnet base material, 7a... Groove of holding means (fixing tool), 10, 10a, 10b, 10c, 10d, 10e... Columnar member, 11... Cylindrical part, DESCRIPTION OF SYMBOLS 12... Column part, 13... Tip part, 14... Fixing part, 20... Adhesion device, D... Direction in which the columnar member extends (longitudinal direction of the columnar member), L1... First line segment, L2... Second line segment.

Claims (8)

an adhesion process for adhering heavy rare earth elements to the surface of the magnet;
a diffusion step of diffusing the heavy rare earth element into the magnet by heating the magnet to which the heavy rare earth element is attached;
Equipped with
The adhesion device used in the adhesion step has a plurality of columnar members,
The adhesion step includes:
a first adhesion step of adhering the paint containing the heavy rare earth element to the tip of each of the plurality of columnar members;
a second adhesion step of adhering the paint to the surface of the magnet by bringing the tips of the plurality of columnar members to which the paint is adhered into contact with the surface of the magnet;
including;
The paint is a paste containing the heavy rare earth element, a binder, and a solvent.
A method for manufacturing rare earth permanent magnets. The columnar member expands and contracts in the direction in which the columnar member extends,
In the second attachment step, the columnar member is contracted by bringing the tip portion into contact with the surface of the magnet.
A method for manufacturing a rare earth permanent magnet according to claim 1. The columnar member includes an elastic body,
Due to the elasticity of the elastic body, the columnar member elastically expands and contracts in the direction in which the columnar member extends;
In the second attachment step, the columnar member is contracted by bringing the tip portion into contact with the surface of the magnet.
A method for manufacturing a rare earth permanent magnet according to claim 1 or 2. At least a portion of the surface of the magnet to which the paint adheres is a curved surface.
A method for producing a rare earth permanent magnet according to any one of claims 1 to 3. Equipped with an adhesion device,
The adhesion device has a plurality of columnar members,
A paint containing a heavy rare earth element is attached to the tip of each of the plurality of columnar members,
The paint adheres to the surface of the magnet by bringing the tips of the plurality of columnar members to which the paint is adhered into contact with the surface of the magnet ,
The paint is a paste containing the heavy rare earth element, a binder, and a solvent.
Rare earth permanent magnet manufacturing equipment. The columnar member expands and contracts in the direction in which the columnar member extends,
The columnar member is contracted by bringing the tip portion into contact with the surface of the magnet.
The rare earth permanent magnet manufacturing apparatus according to claim 5. The columnar member includes an elastic body,
Due to the elasticity of the elastic body, the columnar member elastically expands and contracts in the direction in which the columnar member extends;
The columnar member is contracted by bringing the tip portion into contact with the surface of the magnet.
The rare earth permanent magnet manufacturing apparatus according to claim 5 or 6. At least a portion of the surface of the magnet to which the paint adheres is a curved surface.
The apparatus for producing a rare earth permanent magnet according to any one of claims 5 to 7.

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