JP2004111944A - Radial anisotropic ring magnet and manufacturing method of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radial anisotropic ring magnet which has excellent magnetic characteristics and a manufacturing method of the same in which the ring magnet is formed by a horizontal magnetic field vertical forming method. <P>SOLUTION: The magnet is characterized in that the angle formed by the central axis of the ring magnet and the direction of imparting a radial anisotropy is in the range of 80°to 100°over the whole magnet. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a radial anisotropic ring magnet and a method for manufacturing the same.

Anisotropic magnets made by crushing crystalline magnetic anisotropic materials such as ferrites and rare earth alloys and pressing them in a specific magnetic field are widely used in speakers, motors, measuring instruments, and other electrical equipment. Have been. Among them, magnets having anisotropy in the radial direction are particularly excellent in magnetic properties, can be freely magnetized, and do not require reinforcement for fixing magnets such as segment magnets. Used in brushless motors and the like. In particular, in recent years, a long radial anisotropic magnet has been demanded as the performance of a motor becomes higher.

磁石 A magnet having a radial orientation is manufactured by a vertical magnetic field vertical molding method or a backward extrusion method. The vertical magnetic field vertical forming method is characterized in that a magnetic field is applied from a facing direction through a core from a pressing direction to obtain a radial orientation. That is, in the vertical magnetic field vertical molding method, as shown in FIG. 1, the magnetic field generated in the orientation magnetic field coil 2 is opposed via the cores 4 and 5, the core passes through the die 3, and the molding machine base 1 In the magnetic circuit that circulates through the magnetic powder, the filled magnet powder 8 is radially oriented. In the figure, 6 is an upper punch and 7 is a lower punch.

As described above, in this vertical magnetic field vertical forming apparatus, the magnetic field generated by the coil forms the core, the die forming machine base, and the magnetic path serving as the core. In this case, in order to reduce the magnetic field leakage loss, a ferromagnetic material is used as a material of a portion forming a magnetic path, and an iron-based metal is mainly used. However, the magnetic field strength for orienting the magnet powder is determined as follows. The core diameter is B (magnet powder filling inner diameter), the die diameter is A (magnet powder filling outer diameter), and the magnet powder filling height is L. The magnetic flux that has passed through the upper and lower cores strikes at the center of the core and opposes to the die. The amount of magnetic flux passing through the core is determined by the saturation magnetic flux density of the core, and the magnetic flux density of an iron core is about 20 kG. Therefore, the orientation magnetic field at the inner and outer diameters of the magnet powder filling is obtained by dividing the amount of magnetic flux passing through the upper and lower cores by the inner area and the outer area of the magnet powder filling portion,
2 · π · (B / 2) ² · 20 / (π · B · L) = 10 · B / L...
2 · π · (B / 2) ² · 20 / (π · A · L) = 10 · B ² / (A · L)... Since the magnetic field at the outer circumference is smaller than the inner circumference, 10 kOe or more is required at the outer circumference in order to obtain a good orientation in all the filled portions of the magnet powder. Therefore, 10 · B ² / (AL·L) = 10 , Therefore, L = B ² / a. The height of the compact is about half of the height of the filling powder and becomes about 80% during sintering, so that the height of the magnet is extremely small. As described above, since the saturation of the core determines the strength of the alignment magnetic field, the size, that is, the height of the orientable magnet is determined by the shape of the core, and it is difficult to manufacture a long product in the cylindrical axis direction. In particular, only a very short product could be manufactured with a cylindrical magnet having a small diameter.

後方 In addition, the backward extrusion method requires large facilities, has a low yield, and it has been difficult to manufacture an inexpensive magnet.

As described above, the radial anisotropic magnet is difficult to manufacture by any method, it is difficult to manufacture the mass inexpensively, and the motor using the radial anisotropic magnet has a disadvantage that the cost is very high. there were.

JP-A-2-281721 JP-A-10-55929

In recent years, there has been a strong demand from users for cost reduction in materials and assembly, and there is an urgent need to improve productivity and assemblability of radially anisotropic ring magnets. In addition, high performance is demanded from miniaturization and labor saving. In order to satisfy such user requirements, a long radial anisotropic ring magnet is considered preferable (a long product has an inner diameter <L).

組 み 立 て Assembly costs can be reduced for long products, but the following problems occur when multiple products are stacked for short products. That is, the magnet and the motor core are joined by the adhesive and the magnetic attraction of the magnet and the ferromagnetic motor core. However, when the adhesive is peeled off, the attractive force between the magnets is stronger than the attractive force between the magnet and the core, and the N pole and the S pole are stuck together. As a result, the motor does not play a role. Even in a state where the magnetic poles are not peeled off, a shear stress acts on the adhesive due to the force of the N and S of the magnetic poles sticking to each other, so that the adhesive is easily peeled off. On the other hand, the above-mentioned phenomenon does not occur in the case of an integrated body, and even if the adhesive is peeled off, it is not separated because it is attracted by the magnetic force to the motor core which is a ferromagnetic material.

However, in forming a radially anisotropic ring magnet, molding is performed by a vertical magnetic field vertical molding method shown in FIG. 1, but only a short one can be manufactured by such an ordinary method. In this case, Japanese Patent Application Laid-Open No. 2-281721 proposes a method for manufacturing a long integrated radial magnet. That is, in Japanese Patent Application Laid-Open No. 2-281721, a molded body obtained by orienting and pressing a raw material powder filled in a cavity is transferred to a non-magnetic portion of a die, and then the raw material powder is filled in a cavity of a magnetic portion in the die. Then, the obtained molded body is moved downward, and powder feeding and pressure molding are repeated an arbitrary number of times to obtain a molded body having a large dimension L (hereinafter, referred to as L dimension) in the ring axis direction. A method (hereinafter, referred to as a multi-stage molding method) is proposed.

According to the multi-stage molding method, a radial anisotropic ring magnet having a large L can be manufactured. However, this method repeats powder feeding and molding to form a joint, so that one multilayer molded body is manufactured, so that the molding time is long, which is not suitable for mass production. Since it is constant, there is a problem that cracks are likely to occur at the joint surface of the molded body in the sintered body having the same molded body density. An improvement in this respect is proposed in Japanese Patent Application Laid-Open No. H10-55929. That is, in Japanese Patent Application Laid-Open No. H10-55929, the density of the compact during multi-stage molding is set to 3.1 g / cm ³ or more in a Nd—Fe—B-based magnet, and the final compact (the compact formed by the final compact is finally molded). ), And by forming the molded body to have a density of 0.2 g / cm ³ or more higher than that of the previous molded body (referred to as a preformed body), cracks generated at the joint surface of the molded body are reduced. A proposal has been made.

However, in this method, pressure control must be strictly performed, and the state of the magnet powder greatly varies depending on the particle size and particle size distribution of the magnet powder, and the type and amount of the binder. difficult. In addition, if the density of the preformed body is low, the magnetic properties are poor due to the influence of the second and subsequent magnetic fields, and if the density of the final formed body is low, cracks are generated at the joint surface. Since the orientation is disturbed, it has been extremely difficult to manufacture a long radial anisotropic ring magnet having both characteristics and yield.

The present invention has been made in view of the above circumstances, and has as its object to provide a radial anisotropic ring magnet having good magnetic properties and a method for manufacturing the radial anisotropic ring magnet by a horizontal magnetic field vertical forming method.

The present invention provides the following radial anisotropic ring magnet and a method for manufacturing the same to achieve the above object.
(1) A radially anisotropic ring magnet, wherein the angle formed between the central axis of the ring magnet and the direction in which the radial anisotropy is provided is 80 ° or more and 100 ° or less over the entire magnet.
(2) The radial anisotropic ring according to (1), wherein the average degree of orientation of the magnet powder in the radial direction on a plane perpendicular to the ring magnet center axis in the radial anisotropic ring magnet is 80% or more. magnet.
(3) The radial anisotropic ring magnet according to (1) or (2), wherein a value obtained by dividing a length of the ring magnet in a central axis direction by an inner diameter is 0.5 or more.
(4) A ferromagnetic material having a saturation magnetic flux density of 5 kG or more is used as at least a part of the material of the core of the molding die for a cylindrical magnet, and the magnet powder filled in the mold cavity is formed into a magnet powder by a horizontal magnetic field vertical molding method. A method for producing a radially anisotropic ring magnet by applying an orientation magnetic field and molding, comprising the following steps (i) to (v):
(I) rotating the magnet powder by a predetermined angle in the circumferential direction of the mold while applying a magnetic field;
(Ii) After applying the magnetic field, rotate the magnet powder by a predetermined angle in the circumferential direction of the mold, and then apply the magnetic field again.
(Iii) rotating the magnetic field generating coil with respect to the magnet powder by a predetermined angle in the circumferential direction of the mold during application of the magnetic field;
(Iv) After applying the magnetic field, rotate the magnetic field generating coil by a predetermined angle in the circumferential direction of the mold with respect to the magnet powder, and then apply the magnetic field again.
(V) After applying a magnetic field to one coil pair using a plurality of coil pairs, at least one operation of applying a magnetic field to another coil pair is performed, and more than one direction is applied to the magnet powder in one direction. Applying a magnetic field from the direction, manufactured by pressure molding, the radial anisotropic ring magnet in which the angle between the central axis of the ring magnet and the radial anisotropy providing direction is 80 ° or more and 100 ° or less over the entire magnet. A method for producing a radially anisotropic ring magnet, comprising:
(5) The radially anisotropic ring magnet according to (4), wherein, when rotating the charged magnet powder, at least one of the core, the die, and the punch is rotated in the circumferential direction to rotate the charged magnet powder. Manufacturing method.
(6) When the filled magnet powder is rotated after applying the magnetic field, the value of the residual magnetization of the ferromagnetic core and the magnet powder is 50 G or more, and the magnet powder is rotated by rotating the core in the circumferential direction. (4) The method for producing a radial anisotropic ring magnet.
(7) The method for producing a radial anisotropic ring magnet according to (4) to (6), wherein the magnetic field generated in the horizontal magnetic field vertical forming step is 0.5 to 10 kOe.
(8) The method for producing a radially anisotropic ring magnet according to (4) to (7), wherein the magnetic field generated by the horizontal magnetic field vertical molding device immediately before or during molding is 0.5 to 3 kOe.
(9) After applying the magnetic field one or more times, the magnetic powder is rotated at 60 to 120 ° + n × 180 ° (n is an integer of 0 or more) with the magnetic field generated from the coil set to 0 to less than 0.5 kOe. (4) to (8), wherein a magnetic field having a magnitude of 1/20 to 1/3 of the magnetic field applied before is applied, and molding is performed after or during the application. Manufacturing method of ring magnet.

According to the present invention, it is possible to supply a large amount of radially anisotropic ring magnets that are excellent in performance and good in assembling work at low cost.

According to the present invention, a radial anisotropic ring magnet having good magnetic properties can be provided.

Hereinafter, the present invention will be described in more detail. In the following, a cylindrical sintered magnet of Nd-Fe-B system will be mainly described, but it is also effective in the manufacture of ferrite magnets, Sm-Co-based rare earth magnets, various bonded magnets, and the like. It is not limited to.

The radial anisotropic ring magnet of the present invention is preferably manufactured by press-molding by displacing the magnetic field immediately before molding, and over the entire magnet, as shown in FIG. The angle formed by the anisotropy direction is 80 ° or more and 100 ° or less. In this case, the average degree of orientation of the magnet powder in the radial direction on the plane perpendicular to the ring magnet center axis is preferably 80% or more, and the value obtained by dividing the length of the ring magnet in the center axis direction by the inner diameter is as follows. It is preferably 0.5 or more.

As the angle between the ring magnet center axis and the radial anisotropy imparting direction deviates from the range of 80 ° or more and 100 ° or less, only the cosine component of the amount of magnetic flux generated from the radial anisotropic ring magnet contributes to the rotational force, Since the motor torque is reduced, the angle between the center axis of the ring magnet and the direction in which the radial anisotropy is provided is set to 80 ° or more and 100 ° or less. In addition, most of the practical use of the radial ring magnet is an AC servomotor, a DC brushless motor or the like. When a radial anisotropic ring magnet is used for the motor, the magnet or the stator is skewed as a countermeasure against cogging. If the angle between the center axis of the ring magnet and the direction in which the radial anisotropy is provided is out of the range of 80 to 100 °, the effect of skew is reduced. In particular, when the angle between the center axis of the ring magnet and the direction in which the radial anisotropy is formed at the end of the radially anisotropic ring magnet in the L dimension greatly deviates from 80 to 100 °, this tendency becomes remarkable. When the skew is applied, there is a portion where the poles are opposite at the end and the center, and cogging is reduced by gradually changing the ratio of the magnetic flux amount between the N pole and the S pole linearly. However, the angle between the center axis of the ring magnet and the direction of imparting radial anisotropy at the end portion is largely deviated from 80 to 100 °, and the amount of magnetic flux at the end portion between the central portion and the opposite pole decreases.

磁石 A magnet with a particularly large deviation at the end as described above occurs in the following manufacturing method. That is, conventionally, in forming a radially anisotropic ring magnet, forming is performed by a vertical magnetic field vertical forming method shown in FIG. 1. However, as described above, only a short one can be manufactured by a normal method. In the multi-stage molding method, peeling occurs from the joining surface, causing disturbance of the magnetic poles, and also causes separation, and surface treatment cannot be performed on the peeled surface, which causes corrosion. In FIG. 1, when the orientation is performed by a vertical magnetic field vertical forming press, when a magnetic field equal to or more than the saturation magnetization of the core is applied in order to lengthen the core, after the core is saturated, the magnetic field of the upper punch magnetic field coil and the lower punch magnetic field coil are reduced. Although the lines of magnetic force collide against each other without passing through the core and a magnetic field is generated in the radial direction, the angle between the center line of the core and the direction in which the radial anisotropy is imparted greatly deviates from 80 to 100 °, and this tendency is It becomes larger near the upper and lower punches. For this reason, the angle between the center axis of the ring magnet and the direction in which the radial anisotropy is provided becomes small at the end of the magnet, and this method is not suitable for manufacturing a radial ring magnet.

Therefore, it is necessary that the angle between the central axis of the ring magnet and the direction in which the radial anisotropy is provided is 80 ° or more and 100 ° or less over the entire magnet.
Further, the degree of orientation f of the magnet is calculated by the following equation.
f = Br / [Is × {ρ / ρ ₀ × (1-α)} ^2/3 ]
Br: residual magnetic flux density Is: saturation magnetization ρ: sintered body density ρ ₀ : theoretical density α: volume fraction of non-magnetic phase

If the degree of orientation is low, the amount of magnetic flux generated from the magnet will be small, and the motor torque will be small.In addition, the magnetization may be impaired. In many cases, the decrease in magnetization may be a serious problem. Therefore, in the radial anisotropic ring magnet, the average degree of orientation of the magnet powder is preferably 80% or more, more preferably 80 to 100%.

Also, in consideration of assembly workability, the value obtained by dividing the length of the ring magnet in the center direction by the inner diameter of the ring magnet (L dimension / magnet inner diameter) is 0.5 or more, preferably 0.5 to 50.

は As a method for manufacturing such a radial ring magnet, it is preferable to adopt the following horizontal magnetic field vertical forming method. Here, FIG. 3 is an explanatory view of a horizontal magnetic field vertical forming apparatus for performing orientation in a magnetic field when forming a cylindrical magnet, and particularly a horizontal magnetic field vertical forming machine for a motor magnet. Here, as in the case of FIG. 1, 1 is a molding machine stand, 2 is an orientation magnetic field coil, 3 is a die, and 5a is a core. 6 is an upper punch, 7 is a lower punch, 8 is a charged magnetic powder, and 9 is a pole piece.

In the present invention, at least a part, preferably the whole, of the core 5a is formed of a ferromagnetic material having a saturation magnetic flux density of 5 kG or more, preferably 5 to 24 kG, more preferably 10 to 24 kG. Examples of the core material include a ferromagnetic material using a material such as an Fe-based material, a Co-based material, or an alloy thereof.

Thus, when a ferromagnetic material having a saturation magnetic flux density of 5 kG or more is used for the core, when an orientation magnetic field is applied to the magnet powder, the magnetic flux draws lines of magnetic force close to radial because it tends to enter the ferromagnetic material perpendicularly. Therefore, as shown in FIG. 4A, the magnetic field direction of the magnet powder filling portion can be made closer to the radial orientation. On the other hand, conventionally, the core 5b is entirely made of a material having a non-magnetic or a saturation magnetic flux density equivalent to that of the magnet powder. In this case, the lines of magnetic force are parallel to each other as shown in FIG. The vicinity is the radial direction, but the direction of the orientation magnetic field by the coil becomes higher and lower. Even when the core is formed of a ferromagnetic material, if the saturation magnetic flux density of the core is less than 5 kG, the core is easily saturated, and the magnetic field is close to that of FIG. . In addition, if it is less than 5 kG, it becomes equal to the saturation density of the charged magnet powder (saturation magnetic flux density of the magnet × filling rate), and the direction of the magnetic flux in the charged magnet powder and the ferromagnetic core becomes equal to the magnetic field direction of the coil.

Also, when a ferromagnetic material of 5 kG or more is used for a part of the core, the same effect as described above can be obtained and effective, but it is preferable that the whole is a ferromagnetic material.

However, simply forming the core material from a ferromagnetic material does not result in radial orientation in a direction near the direction perpendicular to the direction of the orientation magnetic field by the coil. When there is a ferromagnetic material in the magnetic field, the magnetic flux tries to enter the ferromagnetic material perpendicularly and is attracted to the ferromagnetic material. I do. For this reason, when the ferromagnetic core is disposed in the mold, a good orientation is obtained by the strong magnetic field in the magnetic field direction of the ferromagnetic core in the filled magnet powder, and the orientation is not so much in the vertical direction. To compensate for this, the magnet powder is relatively rotated during or after application to the magnetic field generated by the coil, and the incompletely oriented part is reoriented by changing the magnetic field with a strong magnetic field part in the magnetic field direction, Good magnets can be obtained. More preferably, it is preferable to relatively rotate the magnetic field after application or in a magnetic field of 1/3 or less of the magnetic field initially applied. Note that the initially oriented portion may become a vertical portion during subsequent orientation, but since the magnetic flux density in this portion is low, the initial good orientation is not disturbed much.

Here, as a method of rotating the magnet powder relatively to the magnetic field generated by the coil, the following (i) to (v)
(I) rotating the magnet powder by a predetermined angle in the circumferential direction of the mold while applying a magnetic field;
(Ii) After applying the magnetic field, rotate the magnet powder by a predetermined angle in the circumferential direction of the mold, and then apply the magnetic field again.
(Iii) rotating the magnetic field generating coil with respect to the magnet powder by a predetermined angle in the circumferential direction of the mold during application of the magnetic field;
(Iv) After applying the magnetic field, rotate the magnetic field generating coil by a predetermined angle in the circumferential direction of the mold with respect to the magnet powder, and then apply the magnetic field again.
(V) Using a plurality of coil pairs, applying a magnetic field to one coil pair, and changing the magnetic field by repeating at least one of the operations of applying a magnetic field to another coil pair once or multiple times to change the magnetic field. Is what you do.

In addition, as for the rotation of the charged magnet powder, as shown in FIG. 5, if the magnet powder can be rotated relatively to the direction of the magnetic field generated by the coil, if the orientation magnetic field coil 2, the core 5a, the die 3, the upper and lower punches 6, 7 Either may be rotated. In particular, when the filled magnet powder is rotated after the application of the magnetic field, if the residual magnetization of the ferromagnetic core and the magnet powder is 50 G or more, preferably 100 G or more, the magnet powder can be placed between the magnetic powder and the ferromagnetic core. Since the attractive force is generated, the magnet powder can be rotated only by rotating the ferromagnetic core.

Using a plurality of coil pairs, applying a magnetic field to one and then applying a magnetic field to the other is synonymous with rotating the magnetic powder relative to the direction of the magnetic field, so the same effect can be obtained using this method. Can be

回 転 In rotation before applying a magnetic field immediately before molding, the applied magnetic field after rotation is small, so if a large magnetic field is applied during rotation, the effect of the last magnetic field application will not appear. Therefore, the magnetic field during rotation is preferably 0 to 0.5 kOe. More preferably 0.3 kOe or less, and typically no magnetic field is preferred. Regarding the rotation angle, since the part disturbed by the application of the magnetic field before rotation is perpendicular to the direction of the magnetic field before rotation, the rotation angle is preferably 60 to 120 ° + nx180 to improve the disturbance of this part. ° (n is an integer of 0 or more), more preferably 90 ° + n × 180 ° (n is an integer of 0 or more) ± 10 °. Typically 90 ° + n × 180 ° (n is an integer of 0 or more). When the applied magnetic field strength is strong, the magnetic field strength before rotation is strong, and the disturbance from the radial orientation in the direction perpendicular to the magnetic field direction is large, so the magnetic field strength after rotation must be larger than that when the magnetic field before rotation is weak. The disturbance of the orientation is not improved, and if it is too large, disturbance from the radial orientation occurs in the direction perpendicular to the direction of the magnetic field. Therefore, the magnetic field is 1/20 to 1/3 of the magnetic field applied before rotation. More preferably, it should be 1/10 to 1/3.

Here, when the magnetic field generated by the horizontal magnetic field vertical shaping device is large, the core of 5a in FIG. 4a is saturated, and becomes a state close to FIG. 4b. Therefore, the magnetic field is preferably set to 10 kOe or less. When a ferromagnetic core is used, the magnetic flux concentrates on the core, so that a magnetic field larger than the magnetic field generated by the coil is obtained around the core. However, if the magnetic field is too small, a magnetic field sufficient for orientation cannot be obtained even around the core, so that the magnetic field is preferably 0.5 kOe or more. As described above, magnetic flux gathers around the ferromagnetic material and the magnetic field increases, so the magnetic field generated by the horizontal magnetic field vertical shaping device here is the magnetic field at a place sufficiently away from the ferromagnetic material, or The value of the magnetic field when the core is removed is measured.

The magnet powder can be rotated relative to the direction of the magnetic field generated by the coil, and the incompletely oriented part can be re-oriented with a strong magnetic field in the direction of the magnetic field. Although the magnetic flux density in this area is small, it has been explained that the initial good orientation is not disturbed much. However, when the generated magnetic field is relatively large, partial disturbance may occur. In such a case, immediately before molding, the magnetic powder is rotated by about 90 ° relative to the coil magnetic field in a state where no magnetic field is applied, and then a magnetic field lower than that during molding, preferably a magnetic field of 0.5 to 3 kOe. By applying and shaping, only the direction of the magnetic field can be reoriented, and a more complete radial orientation can be obtained. If the magnetic field generated by the horizontal magnetic field vertical molding device before molding exceeds 3 kOe, an unnecessary magnetic field is applied to a portion where good orientation has already been obtained when a larger magnetic field is applied as described above. If it is less than 0.5 kOe, the magnetic field is too weak and the orientation is not improved.
Further, in the present invention, the alignment may be performed several times, but it is preferable to lower the magnetic field in multiple steps. In particular, it is preferable to perform the alignment three times. It is more preferable to perform it up to 5 times from the viewpoint of characteristics.

In the present invention, the molding is performed as described above. Otherwise, an orientation magnetic field is applied to the magnet powder by a normal horizontal magnetic field vertical molding method, and the magnetic powder is molded in a pressure range of 50 to 2000 kgf / cm ² , Furthermore, sintering is performed at 1000 to 1200 ° C. under an inert gas, and aging treatment, processing, and the like are performed as necessary to obtain a sintered magnet. Here, in the present invention, a magnet having a required axial length can be obtained by one powder supply and one press, but the magnet may be obtained by a plurality of presses.

The magnet powder is not particularly limited, and is suitable for producing an Nd-Fe-B-based cylindrical magnet, as well as producing ferrite magnets, Sm-Co-based rare earth magnets, various bond magnets, and the like. However, it is preferable to use an alloy powder having an average particle size of 0.1 to 10 μm, particularly 1 to 8 μm.

Hereinafter, the present invention will be described specifically with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.
[Examples and Comparative Examples]

Using Nd, Dy, Fe, Co, M (M is Al, Si, Cu) having a purity of 99.7% by weight and B having a purity of 99.5% by weight, melting and casting in a vacuum melting furnace to obtain Nd ₂ Fe ₁₄ A B-based magnet alloy (Nd _31.5 Dy ₂ Fe ₆₂ Co ₃ B ₁ Cu _0.2 Al _0.3 Si ₁ (wt%)) ingot was produced. The ingot was coarsely pulverized with a jaw crusher, and further subjected to jet mill pulverization in a nitrogen stream to obtain a fine powder having an average particle size of 3.5 μm. This powder was molded with a ferromagnetic core (S50C) having a saturation magnetic flux density of 20 kG by a horizontal magnetic field vertical molding apparatus shown in FIG.

In Example 1, after the coil was oriented in a magnetic field of 4 kOe generated by the coil, the coil was rotated 90 °, an orientation magnetic field of 1 kOe was applied, and molding was performed at a molding pressure of 500 kgf / cm ² . The shape of the mold at this time was φ30 mm × φ17 mm, the cavity was 60 mm, and the filling ratio of the magnet powder was 33%. The molded body was sintered in Ar gas at 1090 ° C. for 1 hour, and subsequently heat-treated at 490 ° C. for 1 hour. With the radial magnet φ26 mm × φ19 mm × L27 mm (L dimension / inner diameter = 1.4) obtained as described above, a magnet of 2 mm square was cut out from the direction of the magnetic field in the center of the magnet, and the magnetism was measured by VSM. : 12.1 kG, iHc: 15 kOe, degree of orientation 89%. The angle formed by the center axis of the ring magnet and the direction of imparting radial anisotropy was 87 ° at the center of L, 91 ° at 3 mm above, and 89 ° at 3 mm below.

In Example 2, the same die and magnet powder as in Example 1 were used, and the orientation was performed in a magnetic field of a magnetic powder filling rate of 32% and a magnetic field of 4 kOe generated by the coil. Then, the die, the core, and the punch were rotated by 90 °. , And an orientation magnetic field of 1.5 kOe was applied, and molding was performed at a molding pressure of 500 kgf / cm ² . The molded body was sintered in Ar gas at 1090 ° C. for 1 hour, and subsequently heat-treated at 490 ° C. for 1 hour. With the radial magnet φ26 mm × φ19 mm × L27 mm (L dimension / inner diameter = 1.4) obtained as described above, a 2 mm square magnet was cut out from the direction of the magnetic field in the center of the magnet, and the magnetism was measured by VSM. : 12.0 kG, iHc: 15 kOe, orientation degree: 88%.

In Example 3, the same mold and magnet powder as in Example 1 were used, the magnetic powder filling rate was set to 32%, and the coil was oriented in a magnetic field of 4.5 kOe generated by the coil. The 2 kG core was rotated 90 °. The residual magnetization of the magnet powder at this time was 600G. Thereafter, an orientation magnetic field of 0.7 kOe was applied, and molding was performed at a molding pressure of 500 kgf / cm ² . The molded body was sintered in Ar gas at 1090 ° C. for 1 hour, and subsequently heat-treated at 490 ° C. for 1 hour. With the radial magnet φ26 mm × φ19 mm × L27 mm (L dimension / inner diameter = 1.4) obtained as described above, a 2 mm square magnet was cut out from the direction of the magnetic field in the center of the magnet, and the magnetism was measured by VSM. : 11.9 kG, iHc: 15 kOe, and orientation degree 87%.

磁石 The magnets of Examples 1, 2, and 3 were then processed into cylindrical magnets of φ25 mm × φ20 mm × L25 mm.

A motor in which the above cylindrical magnet is skew-magnetized at 6 poles and 20 ° by a magnetizing machine shown in FIG. 6 and the magnetized magnet is incorporated in a stator having the same height as the magnet and having a configuration shown in FIG. Produced.
Here, 11 is a cylindrical magnet, 20 is a magnetizer, 21 is magnetic pole teeth of a magnetizer, 22 is a magnetizer coil, 30 is a three-phase motor, 31 is a stator tooth, and 32 is a coil.

(5) The induced voltage when the motor of Example 1 was rotated at 5000 rpm and the magnitude of the torque ripple by a load meter when the motor was rotated at 5 rpm were measured. The same measurement was performed in other examples. Table 1 shows the difference between the maximum value of the absolute value of the induced voltage and the maximum value and the minimum value of the torque ripple.

Example 4 As Example 4, using a horizontal magnetic field vertical forming apparatus capable of rotating the same coil as in Example 1, orientation was performed while rotating 90 ° in a magnetic field of 10 kOe, and then, after rotating 90 ° without a magnetic field, At a molding pressure of 500 kgf / cm ² while reorienting in a magnetic field of 1.5 kOe. The molded body was sintered in Ar gas at 1090 ° C. for 1 hour, and subsequently heat-treated at 490 ° C. for 1 hour. With the radial magnet φ26 mm × φ19 mm × L27 mm (L dimension / inner diameter = 1.4) obtained as described above, a 2 mm square magnet was cut out from the direction of the magnetic field in the center of the magnet, and the magnetism was measured by VSM. : 12.0 kG, iHc: 15 kOe, orientation degree: 88%. A magnet was machined into the same shape as in Example 1, and the motor characteristics were measured.

As Comparative Example 1, the mold shape and the core material were the same as those in Example 1, the die material was a vertical magnetic field vertical molding device using a SKD11 material having a saturation magnetic flux density of 15 kG, and the filling rate of the magnet powder was 33%. A pulse magnetic field of 30 kOe was applied from upper and lower coils so as to face each other. Thereafter, molding was performed at a molding pressure of 500 kgf / cm ² . The molded body was sintered in Ar gas at 1090 ° C. for 1 hour, and subsequently heat-treated at 490 ° C. for 1 hour. The radial magnet thus obtained has an upper and lower part of φ27 mm × φ19.5 mm, a central part of φ26 mm × φ18.7 mm × L27 mm, an average L dimension / inner diameter = 1.35, and a 2 mm square from the magnet central part magnetic field direction. Was cut out and subjected to magnetic measurement using a VSM. As a result, Br: 11.8 kG, iHc: 15 kOe, and the degree of orientation: 87%. At 3 mm above and below the magnet, the angle between the center axis of the ring magnet and the direction in which the radial anisotropy was provided was 120 ° at the top and 60 ° at the bottom. A magnet was machined into the same shape as in Example 1, and the magnet was measured for motor characteristics in the same manner as in Example 1.

As Comparative Example 2, the mold shape and the core material were the same as those in Example 1, the die material was a vertical magnetic field vertical molding device using a SKD11 material having a saturation magnetic flux density of 15 kG, and the filling rate of the magnet powder was 28%. A pulse magnetic field of 3 kOe was applied from upper and lower coils so as to face each other. Thereafter, molding was performed at a molding pressure of 300 kgf / cm ² . The molded body was sintered in Ar gas at 1090 ° C. for 1 hour, and subsequently heat-treated at 490 ° C. for 1 hour. The radial magnet obtained in this manner is 25.8 mm × 19.5 mm × L27 mm, average L dimension / inner diameter = 1.4, a 2 mm square magnet is cut out from the direction of the magnetic field at the center of the magnet, and the magnet is magnetized by VSM. As a result of measurement, Br: 9.5 kG, iHc: 16 kOe, and the degree of orientation were 70%. A magnet was machined into the same shape as in Example 1, and the motor characteristics were measured.

As Comparative Example 3, orientation was performed with a magnetic field of 4 kOe under the same molding conditions as in Example 1, and thereafter, molding was performed without being rotated at the molding pressure of 500 kgf / cm ² in the magnetic field without rotation. The molded body was sintered in Ar gas at 1090 ° C. for 1 hour, and subsequently heat-treated at 490 ° C. for 1 hour. With the radial magnet φ26 mm × φ19 mm × L27 mm (L dimension / inner diameter = 1.4) obtained as described above, a 2 mm square magnet was cut out from the direction of the magnetic field in the center of the magnet, and the magnetism was measured by VSM. : 12.3 kG, iHc: 15 kOe, orientation degree 90%. Next, a 2 mm square magnet of the same shape was cut out from a direction shifted 90 ° on the plane perpendicular to the ring center axis from the direction of the magnetic field at the center of the magnet, and the magnetism was measured. The degree was 18%. A magnet was machined into the same shape as in Example 1, and the motor characteristics were measured.
Table 1 shows the results.

From Table 1, it can be seen that the induced voltage corresponding to the torque is greatly improved in the example as compared with the comparative example, and that the present invention is an excellent method as a method for manufacturing a magnet for a motor.
8 shows the measurement of the surface magnetic flux of the magnetized rotor magnet of Example 1 and FIG. 9 shows the measurement of the surface magnetic flux of the magnetized rotor of Comparative Example 3. In the example, each pole is made uniform and the area of the pole is larger than that of the comparative example, and it can be seen that the example can generate a large magnetic field uniformly.

It is explanatory drawing which shows the conventional perpendicular magnetic field vertical shaping | molding apparatus used when manufacturing a radial anisotropic cylindrical magnet, (a) is a longitudinal cross-sectional view, (b) is AA 'line cross section in (a) figure. FIG. It is explanatory drawing which shows the angle of various radial anisotropy provision directions with respect to the center axis of a ring magnet. It is explanatory drawing which shows one Example of the horizontal magnetic field vertical shaping | molding apparatus used when manufacturing a cylindrical magnet, (a) is a top view, (b) is a longitudinal cross-sectional view. It is explanatory drawing which shows typically the mode of the magnetic field line at the time of a magnetic field generation in the horizontal magnetic field vertical shaping | molding apparatus used at the time of manufacturing a cylindrical magnet, (a) is the shaping | molding apparatus which concerns on this invention, (b) is conventional. This is the case of the molding apparatus. It is explanatory drawing which shows an example of the rotary horizontal magnetic field vertical shaping | molding apparatus in the shaping | molding apparatus used when manufacturing a cylindrical magnet. It is a magnetization schematic diagram which shows a mode that a cylindrical magnet is magnetized using a magnetizer. FIG. 2 is a plan view of a three-phase motor in which a cylindrical magnet having six poles and a plurality of poles are combined with nine stator teeth. FIG. 3 is a diagram showing a surface magnetic flux density when six-pole magnetization is performed on an Nd—Fe—B-based cylindrical magnet produced by a horizontal magnetic field vertical molding machine according to the present invention. It is the figure which showed the surface magnetic flux density at the time of performing 6 pole magnetization to the Nd-Fe-B type | system | group cylindrical magnet produced with the conventional horizontal magnetic field vertical shaping | molding machine.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Forming machine stand 2 Orientation magnetic field coil 3 Die 5a Core 6 Upper punch 7 Lower punch 8 Filled magnet powder 9 Pole piece 11 Cylindrical magnet 20 Magnetizer 21 Magnet pole tooth 22 Magnet coil 30 Three phase motor 31 Stator Tooth 32 coil

Claims (9)

(4) A radial anisotropic ring magnet, wherein the angle between the central axis of the ring magnet and the direction in which the radial anisotropy is provided is 80 ° or more and 100 ° or less throughout the magnet. The radial anisotropic ring magnet according to claim 1, wherein the average degree of orientation of the magnet powder in the radial direction on a plane perpendicular to the center axis of the ring magnet in the radial anisotropic ring magnet is 80% or more. . 3. The radial anisotropic ring magnet according to claim 1, wherein a value obtained by dividing a length of the ring magnet in a central axis direction by an inner diameter is 0.5 or more. A ferromagnetic material having a saturation magnetic flux density of 5 kG or more is used as at least a part of the material of the core of the molding die for cylindrical magnets. The magnet powder filled in the mold cavity is subjected to an orientation magnetic field by a horizontal magnetic field vertical molding method. A method for producing a radially anisotropic ring magnet by applying and molding, comprising the following steps (i) to (v):
(I) rotating the magnet powder by a predetermined angle in the circumferential direction of the mold while applying a magnetic field;
(Ii) After applying the magnetic field, rotate the magnet powder by a predetermined angle in the circumferential direction of the mold, and then apply the magnetic field again.
(Iii) rotating the magnetic field generating coil with respect to the magnet powder by a predetermined angle in the circumferential direction of the mold during application of the magnetic field;
(Iv) After applying the magnetic field, rotate the magnetic field generating coil by a predetermined angle in the circumferential direction of the mold with respect to the magnet powder, and then apply the magnetic field again.
(V) After applying a magnetic field to one coil pair using a plurality of coil pairs, at least one operation of applying a magnetic field to another coil pair is performed, and more than one direction is applied to the magnet powder in one direction. A radial anisotropic ring magnet manufactured by pressure molding by applying a magnetic field from the direction and having an angle between the central axis of the ring magnet and the radial anisotropy imparting direction of 80 ° or more and 100 ° or less over the entire magnet. A method for producing a radially anisotropic ring magnet, comprising: 5. The radially anisotropic ring magnet according to claim 4, wherein, when rotating the filled magnet powder, at least one of a core, a die, and a punch is rotated in a circumferential direction to rotate the filled magnet powder. Method. 5. The method according to claim 4, wherein when the magnetic powder is rotated after application of the magnetic field, the value of the residual magnetization of the ferromagnetic core and the magnetic powder is 50 G or more, and the magnetic powder is rotated by rotating the core in the circumferential direction. A method for producing the radial anisotropic ring magnet according to the above. 7. The method for manufacturing a radial anisotropic ring magnet according to claim 4, wherein a magnetic field generated in the horizontal magnetic field vertical forming step is 0.5 to 10 kOe. The method for manufacturing a radial anisotropic ring magnet according to any one of claims 4 to 7, wherein the magnetic field generated by the horizontal magnetic field vertical molding device immediately before or during molding is 0.5 to 3 kOe. After applying the magnetic field one or more times, the magnetic powder is rotated at 60 to 120 ° + n × 180 ° (n is an integer of 0 or more) with the magnetic field generated from the coil set to 0 to less than 0.5 kOe, and further, The radial anisotropic material according to any one of claims 4 to 8, wherein a magnetic field having a magnitude of 1/20 to 1/3 of the magnetic field applied before is applied, and molding is performed after or during the application. Manufacturing method of sex ring magnet.

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