JP6625299B1 - Rare earth sintered magnet and rotating electric machine using the same - Google Patents

Abstract

Rare earth sintering having an R2T14B phase, wherein R is at least one selected from the group consisting of Nd, Pr, Dy and Tb, and T is at least one selected from the group consisting of Fe and Co The magnet, wherein the cut surface of the rare-earth sintered magnet has a portion mainly composed of R and O, and a T-rich portion having a higher T concentration than the portion mainly composed of R and O. A rare earth sintered magnet, wherein an area ratio of the T-rich portion to a cut area of the rare earth sintered magnet is 5% to 30%.

Description

  The present invention relates to a rare earth sintered magnet and a rotating electric machine using the same.

  Rare earth sintered magnets are manufactured by pressing a raw material powder for a magnet in a magnetic field and then sintering. Since rare earth sintered magnets have large sintering shrinkage and poor dimensional accuracy, processing such as polishing is required after sintering. However, the magnetic properties of rare earth sintered magnets often deteriorate due to the effects of processing.

  Therefore, in order to prevent a decrease in magnetic properties, Patent Document 1 proposes irradiating a neodymium magnet with a solid-state laser having a fundamental wave having a wavelength of 1000 to 1100 nm to cut the neodymium magnet.

JP 2009-000732 A

  However, even if the rare-earth sintered magnet is cut by the method of Patent Document 1, the resulting rare-earth sintered magnet has a problem that the magnetic properties are reduced.

  The present invention has been made to solve the above-described problem, and has as its object to provide a rare-earth sintered magnet in which a decrease in magnetic properties due to a cutting process performed after sintering is suppressed.

The present invention has an R ₂ T ₁₄ B phase, wherein R is at least one selected from the group consisting of Nd, Pr, Dy, and Tb, and T is selected from the group consisting of Fe and Co. At least one kind of rare-earth sintered magnet, wherein the cut surface of the rare-earth sintered magnet has a T concentration higher than that of a portion mainly composed of R and O and a portion mainly composed of R and O. A rare-earth sintered magnet having a high T-rich portion, wherein an area ratio of the T-rich portion to a cut area of the rare-earth sintered magnet is 5% to 30%.

  According to the present invention, it is possible to provide a rare earth sintered magnet in which a decrease in magnetic properties due to a cutting process performed after sintering is suppressed.

It is a schematic structure figure of the processing device used for cutting of the rare earth sintered magnet concerning one embodiment of the present invention. It is a schematic structure figure of the processing device used for cutting of the rare earth sintered magnet concerning one embodiment of the present invention. It is a front view showing the composition of the rotor of the rotary electric machine concerning one embodiment of the present invention. FIG. 2 is a front view illustrating a configuration of a stator of the rotating electric machine according to one embodiment of the present invention. 3 is a composition image and element mapping of a cut surface of the rare earth sintered magnet of Example 1. FIG. 6 emphasizes a T-rich portion in the composition image and the element mapping shown in FIG. 5. 9 is a composition image and element mapping of a cut surface of the rare earth sintered magnet of Comparative Example 1. 5 is a comparison result between the oxygen level at the cut surface of the rare earth sintered magnet of Example 1 and the oxygen level at the cut surface of the rare earth sintered magnet of Comparative Example 1. 9 is a composition image and an element mapping of a cut surface of a rare earth sintered magnet of Comparative Example 2. 4 is a Dy mapping obtained by performing EPMA analysis on a cut surface of the rare earth sintered magnet of Example 1 from the side. 6 is a Dy mapping obtained by performing EPMA analysis on the cut surface of the rare earth sintered magnet of Comparative Example 1 from the side. It is an example of the evaluation result of the magnetic characteristic of a rare earth sintered magnet.

Embodiment 1 FIG.
The rare earth sintered magnet according to the first embodiment is obtained by subjecting a rare earth sintered magnet having an R ₂ T ₁₄ B phase to a specific cutting process. Here, R is at least one selected from the group consisting of Nd (neodymium), Pr (praseodymium), Dy (dysprosium), and Tb (terbium). T is at least one selected from the group consisting of Fe (iron) and Co (cobalt). From the viewpoint of magnetic properties, it is preferable that R essentially includes Nd, and that Nd is partially substituted with at least one selected from the group consisting of Pr, Dy, and Tb. Further, from the viewpoint of magnetic characteristics, T is preferably made of Fe, and a part of Fe is preferably replaced by Co. The rare earth sintered magnet before the cutting process can be manufactured by press-forming raw material powder for the rare earth sintered magnet in a magnetic field and then sintering according to a known method. Further, as the rare earth sintered magnet before cutting, a commercially available rare earth sintered magnet having an R ₂ T ₁₄ B phase can be used.

  1 and 2 are schematic configuration diagrams of a processing apparatus used for cutting a rare earth sintered magnet according to the present embodiment.

In FIG. 1, the processing apparatus includes a laser oscillator 1, a reflection mirror 2, a condenser lens 3, a processing head 4, a pump 5, and a processing table 6. The processing head 4 includes a nozzle for jetting water supplied from the pump 5 toward the workpiece. On the processing table 6, a rare earth sintered magnet 7 as a workpiece is disposed. In the processing apparatus shown in FIG. 1, a laser beam 8 emitted from a laser oscillator 1 such as a YAG laser oscillator or a CO ₂ laser oscillator is reflected by a reflection mirror 2 and then condensed by a condenser lens 3 to be processed by a processing head 4. Sent to Water supplied from the pump 5 is jetted from a nozzle provided on the processing head 4 to form a water column 9. The laser beam 8 sent to the processing head 4 travels in the water column 9 and is irradiated on the rare earth sintered magnet 7. Thus, the cutting process is performed by irradiating the laser light 8 while spraying water on the rare earth sintered magnet 7.

  2, the processing apparatus includes a laser oscillator 1, a reflection mirror 2, a condenser lens 3, a water jet nozzle 10, a pump 5, and a processing table 6. Water is supplied from the pump 5 to the water injection nozzle 10. On the processing table 6, a rare earth sintered magnet 7 as a workpiece is disposed. In the processing apparatus of FIG. 2, although not shown, the water injection nozzle 10 and the rare-earth sintered magnet 7 as a workpiece are immersed in water. In the processing apparatus shown in FIG. 2, a laser beam 8 emitted from a laser oscillator 1 is reflected by a reflection mirror 2 and then condensed by a condenser lens 3. Irradiated on the sintered magnet 7. The water supplied from the pump 5 is injected from the water injection nozzle 10 toward the workpiece. Thus, the cutting process is performed by irradiating the laser light 8 while spraying water on the rare earth sintered magnet 7.

  When a YAG laser is used, for example, the wavelength of the laser beam 8 applied to the rare-earth sintered magnet 7 can be 1064 nm, which is the fundamental wavelength, or 532 nm, which is the second harmonic. Laser power can be, but is not limited to, in the range of 10W to 2000W. Further, the hole diameter of the nozzle provided in the processing head 4 and the water jet nozzle 10 is not limited, but may be in the range of 20 μm to 500 μm. When the hole diameters of the nozzle provided in the processing head 4 and the water injection nozzle 10 are within the above ranges, the rare earth sintered magnet 7 can be appropriately cut without being significantly damaged. The injection pressure of water is preferably in the range of 1 MPa to 50 MPa, and more preferably in the range of 5 MPa to 40 MPa, from the viewpoint of forming a cut surface having a specific structure while performing cutting by the laser beam 8. . If the water injection pressure is less than 1 MPa, the supply of water to the processing portion may be insufficient, and a cut surface having a specific structure may not be formed. On the other hand, if the water injection pressure is more than 50 MPa, it may be difficult to fix the rare earth sintered magnet 7. From the viewpoint of preventing corrosion of the rare-earth sintered magnet 7, water used for the cutting process is preferably one from which at least chlorine ions have been removed. For example, pure water such as distilled water or ion-exchanged water, or ultrapure water may be used. Can be. The water temperature at the time of cutting may be a temperature at which the laser beam 8 is stable, and is, for example, in the range of 5 ° C to 50 ° C. In consideration of workability, the water temperature at the time of cutting is preferably from 15 ° C to 35 ° C.

  The cut surface of the rare-earth sintered magnet 7 obtained by performing the above-described cutting processing includes a portion mainly composed of R and O, and a T-rich portion having a higher T concentration than a portion mainly composed of R and O. Having. The thickness (depth from the cut surface) of the portion mainly composed of R and O and the T-rich portion formed on the cut surface is preferably 0.1 μm to 25 μm, and more preferably 0.5 μm to 10 μm. Is more preferred. When the thickness of the portion mainly composed of R and O and the thickness of the T-rich portion are within the above range, the deterioration of the magnetic properties can be further suppressed. The area ratio of the T-rich portion is 5% to 30%, preferably 10% to 20%, based on the cut area of the rare earth sintered magnet 7. The portion mainly composed of R and O and the T-rich portion on the cut surface of the rare earth sintered magnet can be determined by elemental analysis using an electron probe microanalyzer (EPMA). When the area ratio of the T-rich portion is within the above range, the decrease in magnetic properties due to the cutting process is suppressed.

  From the viewpoint of achieving both corrosion resistance and mechanical strength, the T-rich portion preferably contains Fe and Co. When the rare-earth sintered magnet 7 containing Dy is used as the workpiece, the concentration of Dy in the range of 0.5 μm to 7 μm in the depth direction from the cut surface of the rare-earth sintered magnet 7 increases. 7 is higher than the concentration of Dy in the range of more than 7 μm in the depth direction from the cut surface of No. 7, in other words, Dy is in the range of 0.5 μm to 7 μm in the depth direction from the cut surface of the rare earth sintered magnet 7. A thickened layer may be present. Even if there is a Dy-enriched layer that is likely to coexist with the T-rich portion, no problem occurs in the mechanical strength of the rare-earth sintered magnet 7. The Dy-enriched layer has a possibility that the coercive force of the rare-earth sintered magnet 7 after the cutting process is suppressed from being reduced. In the T-rich portion, in addition to Dy, other elements previously blended in the rare earth sintered magnet 7 may be incorporated as trace components. Examples of such other elements include B, C, N, Al, Si, P, S, Ti, Mn, Ni, Cu, Zn, Ga, Ge, Zr, Pr, Nb, Nd, Tb, and La. , Sm and the like.

  The rare-earth sintered magnet 7 obtained by performing the above-described cutting may be subjected to an additional surface treatment in order to improve corrosion resistance. Examples of the additional surface treatment include a chemical treatment such as phosphoric acid, chromic acid, zirconium-based, titanate-based, manganese-based, and silicate-based, and a surface treatment using hydrofluoric acid. The rare earth sintered magnet 7 may be coated with a paint film such as an epoxy-based, polyester-based, acrylic-based, amide-imide-based, polyimide-based, silicone-based, zinc-flake-containing zinc-rich paint, alkylsilicate-based, or fluororesin-based, as necessary. It may be formed. Further, a powder coating film, an electrodeposition coating film, a vapor deposition film of parylene, or the like may be formed on the rare earth sintered magnet 7 as necessary. If necessary, the rare earth sintered magnet 7 may be formed with a deposited film of aluminum, a deposited film of an aluminum alloy, a TiN-based film, a metal film using a vacuum deposition method, a sputtering method or a wet method. . Examples of the metal-based coating using a wet method include nickel plating, copper plating, tin plating, zinc plating, tin alloy plating, zinc alloy plating, metal plating containing fine particles, electroless Ni-P plating, and electroless Ni-B. Plating and the like. Further, the rare-earth sintered magnet 7 may be subjected to a process for generating an oxide, a nitride, or the like.

  In the present embodiment, the cutting of the rare-earth sintered magnet 7 includes chamfering, partial dimensional processing, drilling, and the like.

  According to the first embodiment, it is possible to provide a rare earth sintered magnet in which a decrease in magnetic properties due to a cutting process performed after sintering is suppressed. Moreover, the rare earth sintered magnet according to the first embodiment has a small rate of decrease in magnetic properties with an increase in operating temperature, and has a good squareness ratio.

Embodiment 2 FIG.
The rotating electric machine according to the second embodiment includes a rotor using the rare-earth sintered magnet of the first embodiment and a stator. FIG. 3 is a front view showing the configuration of the rotor of the rotary electric machine according to Embodiment 2. In FIG. 3, the rotor includes a rotor core 11 and a rare-earth sintered magnet 7. The rotor core 11 is formed by stacking a plurality of steel plates. A shaft hole 12 is formed at the center of the rotor core 11. The rare earth sintered magnet 7 is inserted into a plurality of magnet insertion holes provided in the circumferential direction of the rotor core 11.

  According to the second embodiment, since the rare earth sintered magnet having excellent magnetic properties is incorporated in the rotor, it is possible to increase the efficiency and reduce the size of the rotating electric machine.

Embodiment 3 FIG.
The rotating electric machine according to the third embodiment includes a stator using the rare-earth sintered magnet of the first embodiment and a rotor. FIG. 4 is a front view showing the configuration of the stator of the rotating electric machine according to the third embodiment. In FIG. 4, the stator includes a stator core 13 and a rare earth sintered magnet 7. The stator core 13 is formed by stacking a plurality of steel plates. The rare earth sintered magnet 7 is mounted on a magnet mounting slot provided on the inner peripheral surface of the stator core 13.

  According to the third embodiment, since the rare earth sintered magnet having excellent magnetic properties is incorporated in the stator, it is possible to increase the efficiency and reduce the size of the rotating electric machine.

  In Embodiments 2 and 3, the adhesive used for fixing the rare earth sintered magnet 7 includes epoxy, acrylic, urethane, phenol, cyanoacrylate, silicone, amideimide, hot melt, and the like. Examples include polyimide-based, modified silicone-based, and organic resin components used for coating. The method for curing these adhesives is not limited, and examples thereof include heat curing, room temperature curing, moisture curing, UV curing, and electron beam curing. Alternatively, the rare earth sintered magnet 7 may be fixed using a resin other than a thermosetting resin, such as a thermoplastic resin or a liquid crystal polymer.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited thereto.
<Example 1>
According to a known method, a size of 12.5 mm × 60 mm, a thickness of 4.5 mm, an R ₂ T ₁₄ B phase, R is Nd and Dy, and T is Fe and Co. A rare earth sintered magnet was produced. In this rare earth sintered magnet, the thickness direction was set as the easy magnetization direction.
The rare earth sintered magnet was fixed to a working table of the working apparatus shown in FIG. The cut magnet was cut into a rare earth sintered magnet having a size of 7 mm × 7 mm and a thickness of 1 mm, washed with water and dried to obtain a rare earth sintered magnet of Example 1. In the rare earth sintered magnet after the cutting, the thickness direction was set as the easy magnetization direction.

<Example 2>
According to a known method, a size of 12.5 mm × 60 mm, a thickness of 4.5 mm, an R ₂ T ₁₄ B phase, R is Nd and Dy, and T is Fe and Co. A rare earth sintered magnet was produced. In this rare earth sintered magnet, the thickness direction was set as the easy magnetization direction.
The rare earth sintered magnet was fixed on a processing table of the processing apparatus shown in FIG. After cutting the rare earth sintered magnet into a 7 mm × 7 mm rare earth sintered magnet having a thickness of 1 mm by a water jet at 25 ° C. to 25 ° C., the rare earth sintered magnet of Example 2 was washed with water and dried. A magnet was obtained. In the rare earth sintered magnet after the cutting, the thickness direction was set as the easy magnetization direction.

<Comparative Example 1>
According to a known method, a size of 12.5 mm × 60 mm, a thickness of 4.5 mm, an R ₂ T ₁₄ B phase, R is Nd and Dy, and T is Fe and Co. A rare earth sintered magnet was produced. In this rare earth sintered magnet, the thickness direction was set as the easy magnetization direction.
After cutting the rare earth sintered magnet into a 7 mm x 7 mm rare earth sintered magnet having a thickness of 1 mm using a diamond grindstone while applying water to the rare earth sintered magnet, washing with water and drying are performed to obtain the rare earth sintered magnet of Comparative Example 1. A magnet was obtained.

<Comparative Example 2>
According to a known method, a size of 12.5 mm × 60 mm, a thickness of 4.5 mm, an R ₂ T ₁₄ B phase, R is Nd and Dy, and T is Fe and Co. A rare earth sintered magnet was produced. In this rare earth sintered magnet, the thickness direction was set as the easy magnetization direction.
After cutting the rare earth sintered magnet into a rare earth sintered magnet having a size of 7 mm × 7 mm and a thickness of 1 mm in the same manner as in Example 2 except that water was stirred instead of spraying water, By washing with water and drying, a rare earth sintered magnet of Comparative Example 2 was obtained.

  FIG. 5 shows a composition image (COMPO image) obtained by analyzing a cut surface of the rare earth sintered magnet of Example 1 with a scanning electron microscope (SEM) and a field emission electron probe microanalyzer ( This is an element mapping obtained by analysis with a Field Emission-Electron Probe Micro Analyzer (FE-EPMA).

  As can be seen from the composition image shown in FIG. 5, the cut surface of the rare earth sintered magnet of Example 1 was in a state where the white portion and the gray portion were wavy. From the comparison between the composition image and the element mapping shown in FIG. 5, it was found that the white portion of the composition image was mainly composed of Nd, Dy, and O, and Fe and Co were only slightly detected in this portion. On the other hand, in the gray part of the composition image, the concentrations of Fe and Co were higher than in the white part, and it was found that Nd, Dy, and O were only slightly detected in this part. In the composition image and the element mapping shown in FIG. 5, a portion where the concentration of Fe and Co is high is emphasized as a T-rich portion, and FIG. Comparing at the detection level of elemental mapping, Fe and Co are detected in the T-rich portion twice or more times in the portion other than the T-rich portion, specifically in the portion mainly composed of Nd, Dy and O. Was. Judging from the gray part of the composition image, it is considered that the T-rich part exists from a circular one having a diameter of 0.5 μm to a one having a diameter of 20 μm × 10 μm.

  In the rare earth sintered magnet of Example 1, the area ratio of the T-rich portion was 10% with respect to the cut area. In the rare earth sintered magnet of Example 2, the area ratio of the T-rich portion was 17% with respect to the cut area.

  FIG. 7 is a composition image obtained by analyzing a cut surface of the rare earth sintered magnet of Comparative Example 1 with a scanning electron microscope and an element mapping obtained by analyzing with a field emission electron probe microanalyzer.

  As can be seen from the composition image shown in FIG. 7, no wavy state is observed on the cut surface of the rare earth sintered magnet of Comparative Example 1. From the element mapping shown in FIG. 7, it was found that Nd, Dy, and Fe were distributed over the entire cut surface.

FIG. 8 compares the detection level of oxygen on the cut surface of the rare earth sintered magnet of Example 1 with the oxygen detection level on the cut surface of the rare earth sintered magnet of Comparative Example 1. The comparison of the abundance ratio was performed based on the signal ratio of the corresponding element in the field emission electron probe microanalyzer. The measurement was performed using a field emission type electron probe microanalyzer (JXA-8530F, manufactured by JEOL Ltd.) under the following conditions.
Acceleration voltage: 15.0 kV
Irradiation current: 5.014e-008A,
Irradiation time: 10ms
Number of pixels: 512 pixels × 512 pixels Magnification: 2000 times Number of integration: 1 Beam diameter: 1 μm

  In FIG. 8, the vertical axis indicates the element abundance ratio, and the horizontal axis indicates the oxygen detection level. By multiplying the values of the respective points, the average value of the detected level of oxygen on the cut surface of the rare earth sintered magnet of Example 1 and the average value of the detected level of oxygen on the cut surface of the rare earth sintered magnet of Comparative Example 1 are respectively obtained. Calculated. The average value of the detection levels of oxygen was 74.0 in Example 1 and 36.9 in Comparative Example 1. From these results, it can be seen that the cross section of the rare earth sintered magnet of Example 1 has more oxygen than the cross section of the rare earth sintered magnet of Comparative Example 1.

  FIG. 9 is a composition image obtained by analyzing a cut surface of the rare earth sintered magnet of Comparative Example 2 with a scanning electron microscope and an element mapping obtained by analyzing with a field emission electron probe microanalyzer.

  As can be seen from the composition image shown in FIG. 9, a fine spherical substance and a powdery substance were adhered to the cut surface of the rare earth sintered magnet of Comparative Example 2. From the element mapping shown in FIG. 9, it was found that these deposits were mainly composed of Fe and O, and had a small amount of Nd and Dy.

  FIG. 10 is a Dy mapping obtained by analyzing the cut surface of the rare-earth sintered magnet of Example 1 from the side using a field emission electron probe microanalyzer. From the Dy mapping shown in FIG. 10, the concentration of Dy in the range of 0.5 μm to 7 μm from the cut surface in the depth direction is higher than the concentration of Dy in the range of more than 7 μm in the depth direction from the cut surface. I found out.

  In addition, a Dy detection signal in Dy mapping was binarized, and quantitative comparison was attempted based on luminance when 256 divisions were made. It can be said that the higher the luminance, the higher the ratio of Dy, and the lower the luminance, the lower the ratio of Dy. The Dy binarization level at this time is also shown in FIG. The Dy binarization level in the range of 0.5 μm to 7 μm in the depth direction from the cut surface of the rare earth sintered magnet of Example 1 was 140.4. On the other hand, the Dy binarization level in the range of more than 7 μm in the depth direction from the cut surface of the rare earth sintered magnet of Example 1 was 107.0.

  The Dy binarization level in the range of 0.5 μm to 7 μm in the depth direction from the cut surface of the rare earth sintered magnet of Example 2 was 110.5. On the other hand, the Dy binarization level in the range of more than 7 μm in the depth direction from the cut surface of the rare earth sintered magnet of Example 2 was 103.1.

  FIG. 11 is a Dy mapping obtained by analyzing the cut surface of the rare earth sintered magnet of Comparative Example 1 from the side by using a field emission electron probe microanalyzer. From the Dy mapping shown in FIG. 11, the rare earth sintered magnet of Comparative Example 1 did not show a Dy-enriched layer as seen in the rare earth sintered magnet of Example 1. The detection signal of Dy in the Dy mapping was binarized, and quantitative comparison was attempted based on the luminance at the time of 256 divisions. The Dy binarization level at this time is also shown in FIG. The Dy binarization level in the range of 0.5 μm to 7 μm in the depth direction from the cut surface of the rare earth sintered magnet of Comparative Example 1 was 101.6. On the other hand, the Dy binarization level in the range of more than 7 μm in the depth direction from the cut surface of the rare earth sintered magnet of Comparative Example 1 was 115.4.

From the results shown in FIGS. 5 to 11, the following has been found.
In Comparative Example 2, since water was not sprayed when irradiating the laser beam, Fe was separated from Nd and Dy at the stage where the cut surface was formed, and many fine particles mainly composed of Fe and O were present on the cut surface. It is considered to have adhered. In Comparative Example 2, the area ratio covered by the fine particles was 51% of the cut area.
In the first embodiment, since cutting is performed by irradiating a laser beam while spraying water on the rare-earth sintered magnet, the components constituting the rare-earth sintered magnet are dissolved, re-precipitated on the cut surface and taken in. It is considered that a cut surface having a special composition was formed. The cut surface had a portion mainly composed of Nd, Dy and O, and a portion rich in Fe and Co. Fine particles of 0.3 μm to 5 μm were also slightly observed on the cut surface of the rare earth sintered magnet of Example 1. It is considered that the decrease in magnetic properties is suppressed because the amount of fine particles attached to the cut surface is small. In Example 1, the ratio of the area covered by the fine particles was 1% or less with respect to the cut area.

  In Example 1, it was recognized that the Dy-enriched layer was formed in a specific range from the cut surface toward the depth direction. This is presumed to be because precipitation of Dy occurs preferentially at the stage where the cut surface is formed.

  Next, the magnetic properties of the rare earth sintered magnets obtained in Examples 1 and 2 and Comparative Examples 1 and 2 were evaluated. FIG. 12 is an example of the evaluation results of the magnetic characteristics. In FIG. 12, the vertical axis is the magnetic flux density [T], and the horizontal axis is the magnetic field [MA / m]. The coercive force during operation of a rare earth sintered magnet is an important index. The magnetic field corresponding to a point (90% Br) at which the magnetic flux density becomes 90% of the maximum magnetic flux density Br is defined as a coercive force Hk. Table 1 shows the maximum magnetic flux density Br and the coercive force Hk of each rare earth sintered magnet. The maximum magnetic flux density Br and the coercive force Hk were evaluated at 23 ° C. and 90 ° C., respectively.

  As can be seen from Table 1, at 23 ° C., the maximum magnetic flux density Br and the coercive force Hk of the rare earth sintered magnets of Examples 1 and 2 are higher than the maximum magnetic flux density Br and the coercive force Hk of the rare earth sintered magnet of Comparative Example 1. Was also slightly lower. At 90 ° C., the maximum magnetic flux density Br of the rare earth sintered magnets of Examples 1 and 2 was equal to the maximum magnetic flux density Br of the rare earth sintered magnet of Comparative Example 1. Further, at 90 ° C., the coercive force Hk of the rare earth sintered magnets of Examples 1 and 2 was higher than the coercive force Hk of the rare earth sintered magnet of Comparative Example 1. On the other hand, in the rare earth sintered magnet of Comparative Example 2, the maximum magnetic flux density Br was significantly reduced due to the effect of cutting.

<Example of rotor production>
In the same manner as in Example 1, a rare earth sintered magnet having a size of 5 mm × 10 mm and a thickness of 1.2 mm was cut, washed with water and dried. In the rare earth sintered magnet after the cutting, the thickness direction was set as the easy magnetization direction.
After laminating a plurality of silicon steel plates having a diameter of 200 mm and a thickness of 0.2 mm, they were caulked to produce a rotor core having a thickness of 60 mm. Sixteen 1.3 mm × 5.1 mm magnet insertion holes were provided in the circumferential direction of the rotor core. A shaft hole was formed at the center of the rotor core. Six rare earth sintered magnets prepared above were inserted into one magnet insertion hole. A room temperature curing type two-component acrylic adhesive (Y611 Black S, manufactured by Cemedine Co., Ltd.) was filled in the gap between the magnet insertion holes into which the rare earth sintered magnets were inserted, and the rare earth sintered magnets were bonded to the rotor core. Thereafter, the shaft was press-fitted into the shaft hole to obtain an embedded magnet (Interior Permanent Magnet: IPM) type rotor.

<Example of stator production>
In the same manner as in Example 1, a rare earth sintered magnet having a size of 5 mm × 10 mm and a thickness of 1.2 mm was produced by a near net shape molding method. Next, in the same manner as in Example 2, the burrs and protrusions of the rare earth sintered magnet were removed and dimension processing was performed. In this rare earth sintered magnet, the thickness direction was set as the easy magnetization direction.
After stacking a plurality of silicon steel plates having a thickness of 0.2 mm, a stator core having a thickness of 40 mm was formed by caulking. A through hole having an inner diameter of 160 mm was provided in the center of the stator core. Eight magnet mounting slots of 1.3 mm × 5.1 mm were provided on the inner peripheral surface of the through hole. Permanent magnet-type stators were obtained by mounting the four rare earth sintered magnets prepared above per magnet mounting slot. For mounting the rare earth sintered magnet, a room temperature curing type two-component acrylic adhesive (Y611 Black S manufactured by Cemedine Co., Ltd.) was used.

  Reference Signs List 1 laser oscillator, 2 reflection mirror, 3 condenser lens, 4 processing head, 5 pump, 6 processing table, 7 rare earth sintered magnet, 8 laser beam, 9 water column, 10 water injection nozzle, 11 rotor core, 12 shaft hole , 13 Stator core

Claims (5)

R having the R ₂ T ₁₄ B phase, R is at least one member selected from the group consisting of Nd, Pr, Dy, and Tb; and T is at least one member selected from the group consisting of Fe and Co. A rare earth sintered magnet,
The cut surface of the rare earth sintered magnet has a portion mainly composed of R and O, and a T-rich portion having a higher concentration of T as compared to the portion mainly composed of R and O,
The rare earth sintered magnet, wherein an area ratio of the T-rich portion to a cut area of the rare earth sintered magnet is 5% to 30%.   The rare-earth sintered magnet according to claim 1, wherein the T-rich portion includes Fe and Co.   The concentration of Dy in the range of 0.5 μm to 5 μm in the depth direction from the cut surface of the rare earth sintered magnet is greater than 5 μm in the depth direction from the cut surface of the rare earth sintered magnet. The rare earth sintered magnet according to claim 1, which is higher than the concentration. A rotor comprising: a rotor core formed by stacking steel plates; and a rare-earth sintered magnet according to any one of claims 1 to 3, which is inserted into a magnet insertion hole provided in the rotor core. With the child,
A rotating electric machine including a stator. A stator iron core formed by stacking steel plates, and a stator comprising the rare earth sintered magnet according to any one of claims 1 to 3, attached to the inner peripheral surface of the stator iron core,
A rotating electric machine including a rotor.

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