Sintered magnet for motor, manufacturing method thereof, and permanent magnet type synchronous motor

Abstract

To provide a manufacturing method of a motor sintered magnet capable of improving the yield of a magnet material and reducing a processing time of grinding without reducing the performance of a motor.SOLUTION: A manufacturing method of a motor sintered magnet according to the present disclosure includes a step a of preparing a sintered magnet having a convex first main surface, a second main surface opposite to the first main surface, and side surfaces, a step b of forming a reference plane on a part of the first main surface by partially grinding the top of the first main surface of the sintered magnet, and a step c of forming a surface defining the length and / or width of the sintered magnet by grinding at least a part of the side surface of the sintered magnet, and the sintered magnet having the first main surface including the reference plane as a motor sintered magnet is manufactured.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present disclosure relates to a method for manufacturing a sintered magnet for a motor, a sintered magnet for a motor, and a permanent magnet type synchronous motor including the sintered magnet for a motor. [Background technology]

[0002] Patent Document 1 discloses a manufacturing method for a permanent magnet type synchronous motor (hereinafter sometimes simply referred to as a "motor") that rotates a rotor by passing a current through a stator winding. Specifically, Patent Document 1 discloses that an unprocessed surface (black skin portion) is left on each end of multiple sintered magnets embedded in the iron core of the rotor, and the sintered magnets are arranged so that the unprocessed surfaces are close to each other. The sintered magnets are arranged in such a way that the performance of the motor is not affected by variations in the magnetic properties of the unprocessed surfaces. The sintered magnets come in a variety of shapes, and are used by being embedded in openings provided in the iron core of the rotor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-271723 Summary of the Invention [Problem to be solved by the invention]

[0004] The motor described in Patent Document 1 makes it possible to reduce the processing costs of sintered magnets, thereby enabling prices to be reduced without sacrificing the performance of a permanent magnet type synchronous motor.

[0005] There is a demand for the development of a manufacturing method for a sintered magnet for motors, a sintered magnet for motors, and a permanent magnet type synchronous motor that enable further reduction in manufacturing costs. [Means for solving the problem]

[0006] In one embodiment, the manufacturing method of a sintered magnet for use in a motor of the present disclosure includes the steps of: step a) preparing a sintered magnet having a convex first main surface, a second main surface opposite the first main surface, and a side surface; step b) forming a reference plane on a part of the first main surface by partially grinding a top portion of the first main surface of the sintered magnet; and step c) forming a surface that defines the length and / or width of the sintered magnet by grinding at least a portion of the side surface of the sintered magnet, thereby producing a sintered magnet for use in a motor, the first main surface of which includes the reference plane.

[0007] In one embodiment, the first major surface includes an unground surface.

[0008] In one embodiment, the unground surface has a curved shape on either side of the reference plane.

[0009] In one embodiment, the method further includes a step d of grinding at least a part of the second main surface of the sintered magnet to form another reference plane parallel to the reference plane on the second main surface.

[0010] In one embodiment, steps b and d are carried out simultaneously.

[0011] In one embodiment, step c is performed after step a.

[0012] In one embodiment, the method further comprises a step e of processing the second main surface into a concave curved surface.

[0013] In one embodiment, the area of ​​the reference flat surface on the first main surface is 50% or less of the area of ​​the first main surface.

[0014] In one embodiment, the surface of the first main surface that is not ground is maintained in a black skin state formed by a sintering process.

[0015] In one embodiment, the sintered magnet for motor of the present disclosure is a sintered magnet for motor having a convex first main surface, a second main surface opposite the first main surface, and a side surface, wherein the first main surface includes a reference plane, and the side surface has a surface that defines the length and / or width of the sintered magnet for motor.

[0016] In one embodiment, the first major surface comprises an unfinished surface.

[0017] In one embodiment, the raw surface has a curved shape on either side of the reference plane.

[0018] In one embodiment, the second main surface of the sintered magnet includes another reference plane parallel to the reference plane.

[0019] In one embodiment, the second main surface has a concave curved surface.

[0020] In one embodiment, the area of ​​the reference flat surface on the first main surface is 50% or less of the area of ​​the first main surface.

[0021] In one aspect, the permanent magnet type synchronous motor of the present disclosure comprises a rotor and a stator, the rotor having an iron core and a plurality of permanent magnets fixed to the iron core, and each of the plurality of permanent magnets is a sintered magnet for a motor as described above. Effect of the Invention

[0022] According to the embodiments of the present disclosure, a method for manufacturing a sintered magnet for motors is provided that can improve the yield of magnetic material and reduce the grinding process time without compromising motor performance, thereby reducing the manufacturing costs of high-performance sintered magnets for motors and permanent magnet synchronous motors. [Brief description of the drawings]

[0023] [Figure 1] FIG. 1 is a cross-sectional view that illustrates a schematic configuration example of a permanent magnet type synchronous motor having a conventional embedded magnet structure. [Diagram 2] 1A to 1C are cross-sectional views illustrating steps in a conventional method for producing a semi-cylindrical magnet. [Diagram 3] FIG. 2 is a perspective view showing examples of the shapes of an embodiment (left side) of a sintered magnet for motors according to the present disclosure and a comparative example (right side). [Figure 4] 1 is a cross-sectional view showing examples of the shape of an embodiment of a sintered magnet for motors according to the present disclosure (left side) and a comparative example (right side). FIG. [Diagram 5] 1A to 1C are cross-sectional process diagrams illustrating an embodiment of a method for producing a sintered magnet for motors according to the present disclosure. [Figure 6] FIG. 4 is a perspective view that typically illustrates a step of partially grinding the top portion of a first main surface of a sintered magnet. [Figure 7] FIG. 2 is a perspective view that typically illustrates a step of forming a surface that defines the width of the sintered magnet by grinding the side surface of the sintered magnet. [Figure 8] 1 is a cross-sectional view illustrating a schematic configuration example of a rotor core according to an embodiment of the present disclosure. [Figure 9] 9 is a cross-sectional view showing a schematic state in which magnets are embedded in the rotor core of FIG. 8. FIG. [Figure 10] 1A to 1C are cross-sectional process diagrams illustrating an embodiment of a method for manufacturing a sintered magnet for motors (arch-shaped) according to the present disclosure. [Figure 11] 1 is a cross-sectional view illustrating a schematic configuration example of a permanent magnet type synchronous motor according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Permanent magnets (hereinafter simply referred to as "magnets") are processed into various shapes and used for various applications. Rare earth magnets have excellent magnetic properties and are widely used. Among them, RTB sintered magnets known as neodymium magnets (R is a rare earth element, and T is a transition metal element that always includes Fe) are widely used due to their excellent magnetic properties and relatively low material costs compared to other rare earth magnets (e.g. samarium cobalt magnets).

[0025] RTB sintered magnets are produced by the following method.

[0026] First, a powder of an RTB alloy having a desired composition is prepared. The alloy powder is press-molded to produce a powder compact having a desired shape. The powder compact is sintered to obtain a sintered body. If necessary, the sintered body is subjected to heat treatment such as aging treatment. The sintered body is machined before or after the heat treatment to become a magnet of the desired size and shape. The magnet is then washed to remove grinding powder and grinding fluid (coolant) that have adhered to the magnet surface by machining. Various surface treatments may be performed for the purpose of improving corrosion resistance, etc. After the magnetization process, the sintered body functions as a permanent magnet. For convenience, in this specification, the sintered body in a state before magnetization will also be broadly called a "magnet."

[0027] The RTB sintered magnets thus produced are widely used in permanent magnet synchronous motors. In such motors, for example, torque is generated by a rotating magnetic field formed by copper wire (windings) wound around the teeth of a stator. A plurality of RTB sintered magnets are attached to a rotor core made of a soft magnetic material. Permanent magnet synchronous motors are classified into surface magnet type and embedded magnet type. For example, embedded magnet type motors use sintered magnets embedded in a plurality of openings (holes or recesses) formed inside the rotor core. If a gap with low magnetic permeability occurs inside the core, the magnetic resistance of the rotor increases, deteriorating the motor characteristics. For this reason, the shape and size of the sintered magnet are precisely matched to the shape and size of the openings provided inside the rotor core.

[0028] The openings for embedding magnets inside the rotor core can have simple shapes surrounded by flat surfaces, or shapes that include curved surfaces, such as those generally called "semi-cylindrical" or "arc-shaped". This is because precise control of the distribution of magnetic flux passing through the rotor while the motor is rotating is necessary to improve the performance of the motor, and the shape and arrangement of the sintered magnets are important. For this reason, sintered magnets are processed precisely over a long period of time, and the proportion of the shaved material in the overall product tends to increase. This leads to a decrease in the material utilization rate, i.e., the yield. After being shaved off, magnet materials containing expensive rare earth elements can be recycled from the grinding powder (sludge) and the like, but this inevitably increases the manufacturing cost.

[0029] FIG. 1 is a cross-sectional view that illustrates a schematic configuration example of a permanent magnet type synchronous motor having a conventional embedded magnet structure.

[0030] In the illustrated example, the motor 1000 is a permanent magnet type synchronous motor including a rotor 500 and a stator 600 .

[0031] The rotor 500 has an iron core 52 having a plurality of openings (holes or recesses) 50 extending along the rotation axis, and a plurality of permanent magnets (sintered magnets) 200 arranged in each of the openings 50. In FIG. 1, one permanent magnet (simply abbreviated as "magnet") 200 is shown in a state before being embedded in the opening 50 of the iron core 52. In reality, a magnet is embedded inside each opening 50. The rotor 500 in this example has four poles, and four magnets 200 are embedded. The magnets 200 are magnetized on the outside or inside in the radial direction of the rotor 500, and on the peripheral surface of the rotor 500, north poles and south poles are alternately arranged along the circumferential direction. The number of poles of the rotor 500 is not limited to four poles, and may be two poles or six poles or more.

[0032] Stator 600 has a plurality of teeth 64, each having a winding 62 therearound. For example, a three-phase AC current flows through winding 62 from an inverter circuit (not shown), and magnetic flux is generated that passes from the tips of teeth 64 through the inside of iron core 52 of rotor 500. The interaction between the stator magnetic flux generated by winding 62 and the rotor magnetic flux created by magnet 200 enables rotor 500 to rotate with a desired torque and speed.

[0033] In the example of FIG. 1, magnet 200 has a "semi-cylindrical" cross-sectional shape, and extends in the direction of the rotation axis of rotor 500 with the same cross-sectional shape. The shape of magnet 200 is not limited to a "semi-cylindrical" shape. The shape and size of magnet 200 match the shape and size of opening 50 of iron core 52. To produce such magnet 200, for example, the processing described below has been performed.

[0034] A conventional method for producing a semi-cylindrical magnet 200 will be described with reference to FIG.

[0035] First, as shown in step S1 of FIG. 2, a magnet 200 having a cross section larger than the final cross section of the magnet is prepared. Specifically, a powder compact of a magnet material is sintered by powder metallurgy to obtain the sintered magnet 200. The sintered magnet 200 has a convex first main surface 10, a second main surface 20 opposite to the first main surface 10, and four side surfaces 30. Next, the first main surface 10 of the sintered magnet 200 is processed so as to expose the plane indicated by the line AA in step S2 as a reference surface. This processing is called "reference surface processing." In this way, a flat reference plane 10S is formed on the first main surface 10 as shown in step S3. In addition, a reference surface that defines the length and width of the sintered magnet 200 is also formed by polishing the side surface 30 of the sintered magnet 200.

[0036] The "length and / or width of the sintered magnet" refers to the size of the sintered magnet in a direction parallel to the reference surface. Furthermore, the "plane defining the length and / or width of the sintered magnet" is typically perpendicular to the reference surface of the first main surface.

[0037] Thereafter, in step S4, the entire first main surface 10 is shaped to form the curved surface 10R indicated by the dashed line. This shaping is required to form the curved surface 10R with high dimensional accuracy. Hereinafter, the processing of the sintered magnet 200 into a curved shape may be referred to as "shape processing." In this way, in step S5, the sintered magnet 200 is obtained having the shape and size of the opening 50 of the rotor 500 as shown in FIG. 1.

[0038] According to the conventional processing method described above, in order to perform the shaping process, it is necessary to prepare magnet 200 in step S1 in a large size (ensuring a machining allowance for the shaping process). This reduces the yield (material utilization rate) in both steps S2 and S4. Furthermore, there is also the problem that the process time is long because high-precision processing is performed using a processing machine that performs the shaping process.

[0039] The inventors have earnestly studied solutions to these problems and have investigated the relationship between the processed shape of sintered magnets and motor performance. As a result, they have discovered that even if the first main surface of a sintered magnet is not processed and a part of the surface is left unprocessed, as long as there is a flat reference surface in the center of the first main surface, a sintered magnet can be properly embedded in a rotor with almost no deterioration in motor performance, and have completed the present invention. This makes it unnecessary to secure a machining allowance for processing, and therefore the yield (material utilization rate) can be significantly improved. Furthermore, the machining allowance when processing the reference surface is reduced, and processing is no longer necessary, which shortens the process time.

[0040] Hereinafter, embodiments of the sintered magnet for motors according to the present disclosure will be described.

[0041] First, reference is made to Figs. 3 and 4. The left side of Fig. 3 is a perspective view showing an example of the shape of an embodiment of a sintered motor magnet according to the present disclosure, and the right side of Fig. 3 is a perspective view showing an example of the shape of a conventional sintered motor magnet. In Fig. 3, arrows are drawn indicating the length L and width W of the sintered motor magnet 100. Fig. 4 is a cross-sectional view showing example shapes of the present embodiment (left side) and a comparative example (right side). In Fig. 4, an arrow is drawn indicating the thickness T of the sintered motor magnet 100.

[0042] 3 and 4, the sintered motor magnet 100 in this embodiment has a convex first main surface 10, a second main surface 20 opposite the first main surface 10, and a side surface 30. The first main surface 10 includes a reference plane 10S, and the side surface 30 has surfaces 30W, 30L that define the length and / or width of the sintered motor magnet 100. In this manner, the sintered motor magnet 100 has not been subjected to "shape machining."

[0043] In the illustrated embodiment, the first main surface 10 includes an unground surface 10N. The unground surface 10N has a curved shape on both sides of the reference plane 10S. Such a curved shape is not formed by the above-mentioned shaping process, but is formed by sintering a powder compact whose shape has been adjusted by pressing. The unground surface 10N is typically an "unprocessed surface". Therefore, the surface 10N is maintained in a black skin state formed by the sintering process. In this disclosure, the term "grinding" refers to the physical removal of magnet material from the surface of a sintered magnet using a grindstone or the like to form a "shape", and broadly includes "polishing". A part or all of the unground surface 10N may be subjected to some kind of "surface treatment". This surface treatment includes chemical or physical treatment for improving weather resistance, deposition of a metal layer such as plating, application of resin, etc. In addition, removal of unintentional protrusions or attached unnecessary matter on a part of the unground surface 10N is not included in "grinding" and may be performed as necessary. Furthermore, when performing surface treatments such as plating or resin coating, processing to improve adhesion (for example, shot blasting or barrel polishing) is not included in "grinding" and may be performed as necessary.

[0044] In a preferred embodiment, the area of ​​the reference plane 10S on the first main surface 10 is 50% or less, and more preferably 40% or less, of the area of ​​the first main surface 10. The width of the reference plane 10S is, for example, about 1 mm or more and about 5 mm or less. If the width of the reference plane 10S is smaller than this, it will not function adequately as a reference plane, and if it is larger than this, material and grinding time will be wasted.

[0045] The sintered magnet for motor 100 shown in FIGS. 3 and 4 has a reference surface 30L that defines the length L of the sintered magnet 200 and a reference surface 30W that defines the width W of the sintered magnet 200 formed thereon.

[0046] Next, a method for producing a sintered magnet for motors according to an embodiment of the present disclosure will be described with reference to Fig. 5. Fig. 5 is a process cross-sectional view illustrating an embodiment of the method for producing a sintered magnet for motors according to the present disclosure.

[0047] First, in step a, a sintered magnet 100 is prepared having a convex first main surface 10, a second main surface 20 opposite to the first main surface 10, and a side surface 30. In this example, the second main surface 20 is a substantially flat surface. According to the present disclosure, compared to the conventional method described above, it is not necessary to prepare a cross section larger than the final cross section of the magnet. In other words, when the final magnet size is the same, the size of the sintered magnet 100 prepared can be made smaller than that of the conventional method (magnet 200). This can improve the yield (material utilization rate). For example, in the case of RTB sintered magnets, by eliminating the shaping process, it is possible to achieve an improvement in yield (material utilization rate) of 5% or more, typically 10% or more.

[0048] In step b, the top of the first main surface 10 of the sintered magnet 100 is partially ground to form a reference plane 10S on a part of the first main surface 10. In this example, the grinding process is performed until the surface indicated by the dashed line BB in FIG. 5 is exposed. According to the embodiment of the present disclosure, compared with step S2 in the conventional method, it is not necessary to secure a machining allowance for the shape processing, so that the machining allowance in step b is reduced and the process time can be shortened. In this way, the thickness T of the sintered magnet 100 reaches the design value. Note that when the top of the first main surface 10 is partially ground, the second main surface 20 may be ground at the same time. By grinding the second main surface 20, another reference plane parallel to the reference plane 10S is formed on the second main surface (step d). This allows the thickness T of the sintered magnet 100 and the length and / or width dimensions in the next step c to be specified with higher accuracy.

[0049] Next, in step c, at least a part of the side surface 30 of the sintered magnet 100 is ground to form a surface that defines the length L and / or width W of the sintered magnet 200. In this example, grinding is performed until the surface indicated by the C1-C1 broken line and the surface indicated by the C2-C2 broken line in FIG. 5 are exposed. Although the surface 30W that defines the width W of the sintered magnet 100 is shown in FIG. 5, a surface that defines the length L of the sintered magnet 100 may also be formed. In this way, the manufacturing method of the sintered magnet for motors in the embodiment of the present disclosure produces a sintered magnet whose first main surface includes a reference plane as the sintered magnet for motors. In other words, the process of processing into a curved shape (shape processing) (step S4) is not performed.

[0050] FIG. 6 shows a schematic configuration example of a processing machine 700 that can be used for the grinding process in step b. This processing machine 700 is equipped with a pair of rotating grinding wheels 70. The grinding wheels 70 face each other in parallel. Each grinding wheel 70 has a flat grinding layer. Such a grinding wheel 70 can be produced by electrolytic deposition of diamond abrasive grains (grain size 100 μm to 200 μm). In order to obtain high processing accuracy, the grinding wheel 70 needs to be replaced with a new part as needed.

[0051] With such a processing machine 700, both surfaces in contact with the sintered magnet 100 are ground with the grinding wheels 70, thereby adjusting the thickness T of the sintered magnet 100. Meanwhile, FIG. 7 shows a schematic diagram of the grinding process in step c. This grinding process can be performed by a processing machine 800 having a similar configuration to the processing machine 700 in FIG. 6. The processing machine 800 can adjust the width W of the sintered magnet 100 by grinding the side surfaces of the sintered magnet 100 with a pair of rotating grinding wheels 80. The width W of the sintered magnet 100 may be adjusted using the same processing machine 700 by changing the distance between the grinding wheels 70 of the processing machine 700.

[0052] These grinding processes are not limited to these devices, and grinding devices of other configurations may be used. Grinding of the length L of the sintered magnet 100 can also be performed using a known processing machine. Grinding to form these flat processed surfaces is easier than "shape machining" to obtain a curved shape. The processing machines exemplified in Figures 6 and 7 can grind both sides of the sintered magnet 100 simultaneously, but grinding may also be performed one side at a time. During grinding, a grinding fluid is supplied to the grinding portion.

[0053] In this way, a sintered magnet 100 is obtained in which the first main surface 10 includes a reference plane 10S. As shown in the bottom row of FIG. 5, the first main surface 10 includes an unground surface 10N. The unground surface 10N has a curved shape on both sides of the reference plane 10S. This curved surface is typically an unprocessed surface, and is maintained in a black skin state formed by the sintering process. The reference plane 10S in this embodiment differs from a conventional reference plane during manufacturing in that it maintains a planar shape even when the magnet is finally embedded in a motor and used.

[0054] The magnets thus manufactured are magnetized and then used to manufacture a permanent magnet synchronous motor. The embedding of the magnets into the rotor will now be described.

[0055] Fig. 8 is a cross-sectional view showing a schematic configuration example of the iron core 52 of the rotor 500 in this embodiment. Fig. 9 is a cross-sectional view showing a schematic state in which the magnet 100 is embedded in the iron core of Fig. 8.

[0056] 8 has a number of openings 520. Each opening 520 has a flat portion 10F facing the reference plane 10S of the first main surface 10 of the sintered magnet 100, a flat portion 20F facing the second main surface 20 of the sintered magnet 100, and a flat portion 30F facing the side surface 30W of the sintered magnet 100.

[0057] 9, a gap G may be formed between the unground surface 10N of the sintered magnet 100 and the iron core 52. This gap G is designed to absorb any "variations" that may occur in the shape or dimensions of the surface 10N for each sintered magnet 100, and to prevent physical interference between the surface 10N and the iron core 52. The unground surface 10N of the sintered magnet 100 is typically an unprocessed surface, and therefore has a high degree of surface roughness, making it prone to "variations" in shape and dimensions depending on the state of sintering.

[0058] In the example shown in FIG. 9, the position of the unground surface 10N of the sintered magnet 100 is close to other adjacent sintered magnets 100. The surface 10N may have been oxidized due to the sintering process or subsequent heat treatment, and the magnetic properties of the surface region may be deteriorated compared to the magnetic properties inside the sintered magnet 100. For this reason, it has been conventionally considered necessary to remove the black scale portion with deteriorated magnetic properties by grinding. The present inventor has found that, without being bound by such technical common sense, a decrease in motor performance can be avoided even if the black scale is left on 50% or more of the area of ​​the first main surface 10 of the sintered magnet 100.

[0059] The shape of the sintered magnet 100 in the embodiment of the present disclosure is not limited to a "cylindrical" shape, but may also be a "bow shape."

[0060] An embodiment of a method for obtaining an arched sintered magnet will be briefly described with reference to Fig. 10. Fig. 10 is a process cross-sectional view illustrating an embodiment of a method for producing a sintered magnet for motors according to the present disclosure.

[0061] First, in step a, a sintered magnet 100 is prepared, which has a convex first main surface 10, a second main surface 20 opposite the first main surface 10, and a side surface 30. In a cross section of this sintered magnet 100, the first main surface 10 is convex and the second main surface 20 is concave.

[0062] In step b, the top portion of the first main surface 10 of the sintered magnet 100 is partially ground to form a reference plane 10S on a part of the first main surface 10. In this example, the grinding process is performed until the surface indicated by the dashed line BB in FIG. 5 is exposed. In this way, the thickness T of the sintered magnet 100 reaches the design value. When the top portion of the first main surface 10 is partially ground, the second main surface 20 may be ground simultaneously or separately to form another reference plane parallel to the reference plane 10S on the second main surface (step d).

[0063] In step c, at least a portion of the side surface 30 of the sintered magnet 100 is ground to form a surface that defines the length L and / or width W of the sintered magnet 200. Grinding is performed until the surface indicated by the dashed lines C1-C1 and C2-C2 in FIG. 10 is exposed. As a result, a surface (reference plane) 30W that defines the width W of the sintered magnet 100 is formed. Note that by grinding the other side surfaces 30, a surface (reference plane) that defines the length L of the sintered magnet 100 can also be formed.

[0064] Next, in step e, the second main surface 20 is subjected to shape machining to remove the black skin from the second main surface 20 and form the curved surface 20R (machined into a concave curved surface).

[0065] In this way, a sintered magnet for motors is obtained in which the first main surface 10 includes an unground surface 10N, and the entire second main surface 20 is ground. The unground surface 10N has a curved shape on both sides of the reference plane 10S, and the cross section of the sintered magnet 100 is arch-shaped overall. Note that the shaping process (step e) for the second main surface 20 may be omitted.

[0066] The present invention is effective when applied to rare earth sintered magnets of various compositions. In particular, the effect is remarkable in the case of hard magnet materials that are difficult to grind. Furthermore, the adverse effects of leaving the sintered surface unprocessed without grinding can be relatively negligible when the original magnet performance is high. For this reason, the present invention exerts excellent effects when applied to high-performance rare earth magnets containing Dy or Tb.

[0067] Fig. 11 is a cross-sectional view showing a schematic configuration example of a permanent magnet type synchronous motor according to an embodiment of the present disclosure. A permanent magnet synchronous motor 1100 in this example includes a rotor 500 and a stator 600, and the configuration of the stator 600 is basically the same as that of the motor 1000 in Fig. 1. However, the motor 1100 in this embodiment is a surface mount type in which the sintered magnet 200 in the above embodiment is fixed to the surface of the iron core 52 of the rotor 500. The sintered magnet 200 according to the present disclosure can be used in both embedded and surface mount motors. [Industrial Applicability]

[0068] The sintered magnet for motors and the manufacturing method thereof, as well as the permanent magnet type synchronous motor, of the present disclosure can be widely used in, for example, electric vehicles, hybrid vehicles, etc. They can also be used in generators. [Explanation of symbols]

[0069] 10 first principal surface, 10S reference plane, 20 second principal surface, 30 side surface, 50 opening, 52 iron core, 62 winding, 64 teeth, 100 sintered magnet, 200 sintered magnet, 500 rotor, 600 stator, 1000 permanent magnet type synchronous motor

Claims

1. A step a of preparing a sintered magnet having a convex first main surface, a second main surface opposite to the first main surface, and a side surface; a step b of forming a reference plane on a part of the first main surface by partially grinding a top portion of the first main surface of the sintered magnet; a step c of grinding at least a portion of the side surface of the sintered magnet to form a surface defining a length and / or a width of the sintered magnet; Including, the first main surface includes an unground surface, the unground surface having a curved shape on both sides of the reference plane; A method for manufacturing a sintered magnet for a motor, comprising the steps of: producing a sintered magnet for a motor, the first main surface of which includes the reference plane, the area of ​​the reference plane in the first main surface being 50% or less of the area of ​​the first main surface, and the surface of the first main surface that is not ground being maintained in a black skin state formed by a sintering process.

2. 2. The method for producing a sintered magnet for motors according to claim 1, further comprising a step (d) of grinding at least a part of the second main surface of the sintered magnet to form another reference plane parallel to the reference plane on the second main surface.

3. The method for producing a sintered magnet for motors according to claim 2 , wherein the steps b and d are carried out simultaneously.

4. The method for producing a sintered magnet for motors according to claim 1 , wherein the step c is carried out after the step a.

5. The method for producing a sintered magnet for motors according to claim 1 , further comprising a step e) of processing said second main surface into a concave curved surface.

6. A sintered magnet for motors having a convex first main surface, a second main surface opposite to the first main surface, and a side surface, the first main surface includes a reference plane and an unmachined surface, the unmachined surface having a curved shape on both sides of the reference plane; the side surface has a surface that defines the length and / or width of the sintered motor magnet, a sintered magnet for a motor, wherein an area of ​​the reference plane on the first main surface is 50% or less of an area of ​​the first main surface, and the unprocessed surface is maintained in a black skin state due to sintering.

7. The sintered magnet for a motor according to claim 6 , wherein the second main surface of the sintered magnet includes another reference plane parallel to the reference plane.

8. 8. The sintered magnet for motors according to claim 6, wherein the second main surface has a concave curved surface.

9. A permanent magnet type synchronous motor including a rotor and a stator, The rotor includes an iron core, a plurality of permanent magnets fixed to the iron core, having A permanent magnet type synchronous motor, wherein each of the plurality of permanent magnets is the sintered magnet for motor according to any one of claims 6 to 8.

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