JP2000164420A - Anisotropic magnet and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anisotropic magnet whose oriented state is satisfactory and whose magnetic force is strong. SOLUTION: This anisotropic magnet is manufactured through a molding method for applying a magnetic field from a specific direction in supplying resin molding materials 2 containing magnetic powder 5 into a cavity 31 of a metallic mold 21. When a specific direction Al is a reference, the state of the magnetic powder 5 that an easy axis 6 in the crystal of magnetic powder 5 is set within ±30 deg. is defined as a satisfactory oriented state. In this case, the existence ratio of the magnetic powder 5 in the satisfactory oriented state is set so as to be 75% or more in the area of the surface layer part of an outer peripheral face 3b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anisotropic magnet and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, anisotropic magnets have been used for rotating parts such as motors. The anisotropic magnet generally refers to a magnetic powder crystal in a molded article in which the axes of easy magnetization are aligned in a specific direction (the magnetic powder is oriented). Such an anisotropic magnet is manufactured by performing a magnetizing step after a magnetic field forming step using a magnetic field forming machine.

FIG. 7 shows an example of a conventional mold 44 for a magnetic field forming machine used in manufacturing an anisotropic magnet. The mold 44 for a magnetic field molding machine is made of a magnetic material and includes a movable mold 42 and a fixed mold 43. When the movable mold 42 and the fixed mold 43 are closed, the cavity 4
5 are formed. A cylindrical base material 46 is inserted into the cavity 45, for example, and a resin molding material 48 containing magnetic powder (not shown) is supplied in this state. At the time of material supply, a magnetic field is applied to the cavity 45 from a vertical direction in FIG. Then
As shown in FIG. 8, the magnetic powder 4 in the resin molding material 48
A magnetic-field molded product in which 7 is oriented can be obtained.

[0004]

By the way, when a magnetic field is applied to the mold 44 from a predetermined direction, the lines of magnetic force are usually almost parallel as shown by the broken line in FIG. However, among the surfaces defining the cavity 45 in the mold 44, for example, at a position P1 or the like to which a surface perpendicular to the magnetic field direction A1 belongs, the lines of magnetic force are
(5) It is easy to leak outside. In other words, originally,
The lines of magnetic force to pass through the resin molding material 48 bypass the region outside the cavity 45 made of a magnetic material. Therefore, as shown in FIG. 8, the magnetic field near the location P1 is weakened, and the orientation state of the magnetic powder 47 existing there is worse than in other parts. Therefore, even if the magnetic field molded article obtained in this way is magnetized later, it becomes difficult to obtain a suitable anisotropic magnet having a strong magnetic force.

[0005] As a method of obtaining a suitable anisotropic magnet, for example, a method is employed in which a portion having a poor orientation state in the resin molding material 48 is removed by a predetermined thickness by cutting, and then magnetized. It is possible. However, this method involves cutting, which increases the number of steps. Further, since a loss occurs in the material, the cost may be increased.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an anisotropic magnet having a good orientation state and a strong magnetic force. Another object of the present invention is to provide a manufacturing method capable of obtaining the suitable anisotropic magnet as described above without increasing the number of steps or increasing the cost.

[0007]

In order to solve the above problems, according to the first aspect of the present invention, when a resin molding material containing magnetic powder is supplied into a cavity of a mold, the resin molding material is supplied to the cavity. Anisotropic magnets manufactured through a molding method in which a magnetic field is applied from a predetermined direction, wherein the easy axis of the crystal of the magnetic powder is within ± 30 ° with respect to a specific direction are good. When defined as an oriented state, the gist is an anisotropic magnet whose abundance ratio of the magnetic powder in the well-oriented state is 75% or more in a region of a surface layer portion on an outer peripheral surface.

According to the second aspect of the present invention, when a resin molding material containing a magnetic powder is supplied into a cavity of a mold, an anisotropically manufactured by applying a magnetic field to the cavity from a predetermined direction. Magnetic magnet, wherein the axis of easy magnetization of the crystal of the magnetic powder is ± 20 with respect to a specific direction.
° is defined as a good orientation state,
The gist is an anisotropic magnet in which the abundance ratio of the magnetic powder in the good orientation state is 50% or more in the region of the outer surface layer.

According to a third aspect of the present invention, in the first or second aspect, the anisotropic magnet is obtained by insert-molding a base material made of a ceramic sintered body in the resin molding material. did.

[0010] The invention described in claim 4 is the first to third aspects of the present invention.
In any one of the above, the anisotropic magnet has a rotationally symmetric shape. According to a fifth aspect of the present invention, there is provided a method of manufacturing the anisotropic magnet according to any one of the first to fourth aspects, wherein the magnetic field lines forming the magnetic field in the mold made of a magnetic material have the cavity lines. A gist of the present invention is a method for manufacturing an anisotropic magnet, which comprises arranging a non-magnetic material at a location where leakage is likely to occur outside and applying a magnetic field to the cavity in a predetermined direction in that state.

Hereinafter, the "action" of the present invention will be described. According to the first to fourth aspects of the present invention, the abundance ratio of the magnetic powder in the well-oriented state becomes a predetermined value or more in the region of the surface layer portion on the outer peripheral surface, so that an anisotropic magnet having a strong magnetic force can be obtained. .

According to the third aspect of the present invention, since the base material made of the ceramic sintered body is insert-molded in the resin molding material, for example, the ceramic sintered body is used as a moving body. An anisotropic magnet suitable for the above.

According to the fifth aspect of the present invention, when a non-magnetic material is arranged and a magnetic field is applied, the lines of magnetic force are less likely to leak out of the cavity from the location. Therefore, the magnetic force lines pass through the location on the resin molding material side corresponding to the location, and the magnetic field there is also prevented from weakening. Therefore, the abundance ratio of the magnetic powder in a good orientation state can be reliably increased. In addition, since it is not necessary to perform a cutting process or the like after molding, an increase in the number of steps and an increase in cost can be avoided.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment embodying an anisotropic magnet and a method for manufacturing the same according to the present invention will be described below in detail with reference to FIGS.

FIGS. 1 and 2 show an anisotropic magnet 1 of the present embodiment. The anisotropic magnet 1 is obtained by magnetizing a molded product (that is, an insert molded product) in which a base material 4 made of another material is inserted into a flange portion 3 made of a resin molding material 2. The anisotropic magnet 1
Is a rotating body having a rotationally symmetric shape.

In the present embodiment, a general thermoplastic resin such as nylon or the like is used as the resin molding material 2. The resin molding material 2 contains the magnetic powder 5 together with a small amount of additives. In this embodiment, Sr ferrite is used as the magnetic powder 5. As conceptually shown in FIG. 5B, the Sr ferrite crystal is a hexagonal plate-shaped crystal having an average particle size of about 1.2 μm.
And the average thickness is 0.2 μm. In the drawing, the easy axis 6 of the Sr ferrite crystal is indicated by an arrow. The easy axis 6 is perpendicular to the plane direction of the crystal.

As the substrate 4 made of a ceramic sintered body, a sleeve having a cylindrical shape is selected. Examples of the ceramic sintered body used here include a dense alumina sintered body. The alumina sintered body is a non-magnetic material. The outer peripheral surface 4 a of the base material 4 is in close contact with the inner peripheral surface 3 a of the flange portion 3 made of the resin molding material 2.

In the anisotropic magnet 1, a surface layer of the outer peripheral surface 3b of the flange portion 3 is magnetized, and a permanent magnet (not shown) is formed at the portion. Therefore, this anisotropic magnet 1 can be used, for example, as a thrust bearing member of a motor in a dental polishing apparatus.

FIG. 3 shows a main part of a magnetic field injection molding machine 11 for manufacturing the anisotropic magnet 1. A movable plate 12 and a fixed plate 13 are installed on a base constituting the magnetic field injection molding machine 11 so as to face each other. In FIG. 3, a link mechanism 14 as driving means for closing and opening the mold is connected to the outer end face side of the movable platen 12. Therefore, the movable platen 12 can be moved by the link mechanism 14 by a predetermined length in the vertical direction in FIG.

On the other hand, on the outer end surface side of the fixed platen 13, a nozzle portion 16 at the tip of the screw cylinder 15 is arranged. At the base end side of the screw cylinder 15 as a material supply means, a hopper (not shown) for charging a raw material is provided. The screw cylinder 15 can move forward and backward by a predetermined length along its own longitudinal direction. Therefore, when the screw cylinder 15 is at the forward position, the nozzle portion 16 is inserted into a through-hole (not shown) provided in the fixed platen 13.

The movable plate 12 and the fixed plate 13 both house magnetic field generating means 17. The magnetic field generating means 17 in the present embodiment is an electromagnet 18 having a coil wound around a core, and generates a strong magnetic field when energized. A plurality of tie bars 19 made of a magnetic material such as iron are interposed between the movable platen 12 and the fixed platen 13. Therefore, these tie bars 19 serve as a return yoke when the electromagnet 18 forms a closed magnetic circuit.

This magnetic field injection molding machine 11 has a mold 21. As shown in FIGS. 3 and 4, the mold 21 includes a movable mold 22 and a fixed mold 23. The movable die 22 is attached to a central portion on the inner end surface side of the movable platen 12, and the fixed die 23 is attached to a central portion on the inner end surface side of the fixed platen 13. That is, the movable mold 22 and the fixed mold 23
Are arranged in a state of facing each other.

A circular concave portion 24 is formed at the center of the inner end surface of the fixed die 23, and a cylindrical portion 25 is formed at the center of the concave portion 24. The fixed mold 23 has a plurality of gates 26. One end of each gate 26 is recessed 24
And the other end reaches the through hole where the nozzle portion 16 is inserted.

The movable mold 22 is constituted by assembling two mold pieces 27 and 28 integrally. The sub-mold piece 28 formed in a cylindrical shape is arranged on the outer peripheral portion so as to surround the main mold piece 27. The inner end surface side of the movable mold 22 is formed in a concave shape, and a circular concave portion 30 is provided on the bottom surface of that portion.

When the mold is closed, a cavity 31 is formed at the interface between the movable mold 22 and the fixed mold 23. More specifically, the fixed type 23
The cavity 31 is defined by the inner end face of the main mold piece 27, the inner end face of the main mold piece 27, and the inner peripheral face 28a of the sub mold piece 28. As a material for forming the fixed mold 23, an iron-based metal (magnetic steel), which is a magnetic material, specifically, an SK material (JIS G 4401) which is a carbon tool steel in the present embodiment is used. . The value of the residual magnetic flux density Br of the metal material is:
0.1 to 1.0 (T: Tesla). The same metal material as described above is also used for the material for forming the main mold piece 27 of the movable mold 22. In addition, SKH material ((JIS G4403)) which is a high speed tool steel material, and SKH material which is an alloy tool steel material
Various tool steel materials such as S material, SKD material, and SKT material (JIS G 4404) may be used.

On the other hand, the forming material (ie, the first material) of the sub-mold piece 28 of the movable mold 22 includes the fixed mold 23 and the main mold piece 2.
A material different from the forming material of No. 7 (that is, the second material) is used. That is, the forming material of the sub-mold piece 28 is
In addition, it is necessary that the residual magnetic flux density Br is relatively small as compared with the material for forming the main mold piece 27.

The sub-mold piece 28 defining the cavity 31
The inner peripheral surface 28a has a direction A of magnetic field as shown in FIG.
The plane is perpendicular to 1 (that is, the direction A1 of the line of magnetic force). The portion P1 to which the surface 28a belongs is a portion P1 where magnetic lines of force are originally apt to leak out of the cavity 31.
You can say that. From the above, in the present embodiment, the sub-mold piece 28 made of the first material having a relatively low residual magnetic flux density Br is disposed at the location P1.

The width of the cavity 31 along the direction A1 of the magnetic field (more specifically, in this embodiment, the width of the cavity 31 at the outer peripheral portion of the flange portion 3 (see FIGS. 4 and 5)
(See (a))) is T. At this time, the thickness W of the portion P1 formed of the first material in the direction orthogonal to the direction A1 of the magnetic field is set to at least T / 2 or more, preferably T or more, and more preferably 2T or more. Is better. If the thickness W is too small, the function of preventing the leakage of the lines of magnetic force may not be sufficiently secured at the point P1. If the thickness W does not have a certain level, the mold 21 cannot have sufficient mechanical strength, and cannot withstand the pressure applied from the cavity 31 during the material injection.

In the present embodiment in which the width of the cavity 31 is set to T = 4.0 mm, the thickness W is set to a sufficiently large value, specifically, to about W = 8 mm. Further, the residual magnetic flux density Br of the first material is 1/100 or less, more preferably 1/250 or less, especially 1/250 of the residual magnetic flux density Br of the second material.
It is preferably 1000 or less. This is because by selecting two kinds of materials having a sufficiently large difference in residual magnetic flux density Br, the function of preventing leakage of the lines of magnetic force becomes more reliable. The first material is preferably a completely non-magnetic material, rather than a weak magnetic material or semi-magnetic material. This is because the lines of magnetic force have the property of hardly passing through the non-magnetic material. On the other hand, the second material is preferably a ferromagnetic material.

From the above, in the present embodiment, the
Austenitic stainless steel (that is, SUS300 series) is selected as the material for (1). Austenitic stainless steel is a non-magnetic material. The surface of the stainless steel is preferably subjected to a surface treatment to increase the hardness.

Next, an example of a method for manufacturing the anisotropic magnet of the present embodiment using the above-described magnetic field injection molding machine 11 will be described. In an initial state, the mold 21 is opened, and the resin molding material 2 in a heated and molten state is supplied in advance into the hopper. The screw cylinder 15 is at the retracted position, and the nozzle portion 16 is not inserted into a through hole (not shown) provided in the fixed platen 13.

Here, the base material 4 is attached to the cylindrical portion 25 of the fixed mold 23.
Are set so as to be fitted together, and then the link mechanism 14 is set.
By driving the movable mold 22 by driving the
Close the mold.

Next, by energizing the electromagnet 18 to generate a magnetic field, a closed magnetic circuit as shown in FIG. 3 is formed. The direction A1 of the magnetic field generated at this time is a direction from the upper side to the lower side in FIG. The lines of magnetic force forming the magnetic field are parallel as shown by the broken lines in FIG. 4, enter the cavity 31 from the fixed mold 23 side, pass through the cavity 31 and escape to the movable mold 22 side.

Subsequently, the screw cylinder 15 is advanced to an inserted state, and the molten resin molding material 2 is transferred to the gate 26.
And is injected into the cavity 31 through. As a result, the cavity 31 is completely filled with the resin molding material 2. At this time, the magnetic lines of force passing through the cavity 31 act on the magnetic powder 5 in the resin molding material 2 and cause the easy axis 6 to be directed in the direction A1 of the magnetic field in a very short time. That is, the magnetic powder 5 is oriented in a specific direction by the action of the lines of magnetic force.

When several seconds to several tens of seconds elapse after the injection, the resin molding material 2 cools and hardens, and as a result, a magnetic field molded product in which the inserted base material 4 and the resin molding material 2 are integrated is obtained. . After that, the mold 21 is opened, and the magnetic field molded product is taken out of the cavity 31. Furthermore, if a permanent magnet is formed on the surface layer of the outer peripheral surface 3b of the flange portion 3 by performing a magnetizing operation using a dedicated thrust magnetizing yoke (not shown), a desired anisotropic magnet 1 is completed.

[0036]

EXAMPLES [Test Method] Here, a sample of an example and a sample of a comparative example were prepared, and a test for comparing both samples was performed.

In the embodiment, the metal mold 21 shown in FIG. 4 is used, and a magnetic field molded product is first manufactured in accordance with the above-mentioned method, and then, a predetermined condition (1000
V) The magnet was fully magnetized. As shown in FIG. 6A, the lower half of the permanent magnet formed on the surface layer of the outer peripheral surface 3b has N poles and the upper half has S poles. The thickness of the outer peripheral portion of the flange portion 3 is 4.0 mm, which is equal to the width T of the cavity 31. The reference (zero reference) of the position in the thickness direction of the anisotropic magnet 1 is set at the height of the upper end face of the flange portion 3.

On the other hand, in the comparative example, a magnetic field molded product was manufactured using the mold shown in FIG. Then, this was magnetized under the same conditions as above to obtain an anisotropic magnet. The strength of the surface magnetic flux density (mT) on the outer peripheral surface 3b of the flange portion 3 was measured for each of the obtained two samples by a conventionally known method. The result of the example is shown in the graph of FIG. 6C, and the result of the comparative example is shown in the graph of FIG. 6B.

For the two samples, the flange portion 3 was cut in parallel along the axial direction, and the cross section of the surface layer of the outer peripheral surface 3b was observed with a SEM using a microscope.
Thereby, the orientation state of the magnetic powder 5 was investigated. Then, the quality of the orientation state was determined by the following method.

First, those in which the axis of easy magnetization 6 of the crystal of the magnetic powder 5 is within an angle range of ± 30 ° with respect to the direction A1 of the magnetic field are defined as “good orientation state” for convenience. In this case, the outer peripheral surface 3 of the resin molding material 2
The abundance ratio (%) of the magnetic powder 5 in the well-oriented state was measured in the predetermined thickness range region of the surface layer portion b. Note that the predetermined thickness range region refers to a region of half the thickness T of the outer peripheral portion of the flange portion 3, that is, a region of 2.0 mm (= T / 2). Also, when the angle range of the easy magnetization axis 6 is set to be as narrow as ± 20 °, similarly, the abundance ratio (%)
I tried to measure. [Results] As can be seen by comparing FIGS. 6B and 6C, the difference in the surface magnetic flux density between the sample of the example and the sample of the comparative example was larger than that of the sample of the comparative example.
Therefore, it was confirmed that the sample of the example had a better magnetized state on the surface layer of the outer peripheral surface 3b and was a suitable anisotropic magnet 1 having a strong magnetic force.

In the sample of the embodiment, the outer peripheral surface 3b
The residual magnetic flux density Br at a predetermined thickness (i.e., 2.0 mm) of the surface layer portion 3b is 1.5 times to that of the sample of the comparative example.
It turned out that it was 2.0 times.

Next, when a microscope was observed, FIG.
As schematically shown in (a) and (b), in the sample of the example, the orientation state of the magnetic powder 5 in the surface layer of the outer peripheral surface 3b was extremely high. In contrast, FIG.
As schematically shown in (a) and (b), in the sample of the comparative example, the orientation state of the magnetic powder 5 at the same location was not so high. That is, in the example, it is concluded that the magnetic field did not weaken in the vicinity of the point P1 where the magnetic lines of force easily leak out of the cavity 31, and the orientation state of the magnetic powder 5 existing there did not deteriorate.

When the angle range was set within ± 30 °, the abundance ratio of the magnetic powder 5 in the good orientation state was about 80% in the example, whereas the comparative example was as low as 40%. Stopped at Further, when the angle range was set within ± 30 °, the abundance ratio of the magnetic powder 5 in a good orientation state was about 60% in the example, whereas it was as low as 30% in the comparative example. .

Therefore, according to the present embodiment, the following effects can be obtained. (1) In the anisotropic magnet 1 of the present embodiment, the abundance ratio of the magnetic powder 5 in the well-oriented state has an extremely high value in the surface layer of the outer peripheral surface 3b of the flange 3 as described above. Therefore, even if the magnetizing step is performed under the same conditions as in the related art, it is possible to obtain a suitable anisotropic magnet 1 having a stronger magnetic force than the conventional one.

(2) The anisotropic magnet 1 of the present embodiment is a rotating body formed by insert molding a base material 4 made of an alumina sintered body into a resin molding material 2. Therefore, the anisotropic magnet 1 is suitable for applications such as bearings using an alumina sintered body as a rotary sliding portion.

(3) In the present embodiment, a sub-mold piece 28 made of a non-magnetic material is placed at a position P 1 where magnetic lines of magnetic force for forming a magnetic field easily leak out of the cavity 31 in a mold 21 mainly made of a magnetic material. Have been placed. Then, in this state, molding is performed while applying a magnetic field to the cavity 31 from a predetermined direction, thereby producing a magnetic field molded product. Accordingly, as a result, it is difficult for the magnetic field lines to leak from the location P1 to the outside of the cavity 31. As a result, the magnetic field lines pass through the surface layer of the outer peripheral surface 3b of the flange portion 3, and the magnetic field therefrom is also prevented from weakening. Therefore, the magnetic powder 5 in a good orientation state
Can be reliably increased, and a suitable magnetic-field molded product and a suitable anisotropic magnet 1 can be obtained. In addition, since it is not necessary to perform a grinding process or the like after molding, an increase in the number of steps and an increase in cost can be avoided.

The embodiment of the present invention may be modified as follows. The base material 4 inserted into the cavity 31 is not limited to the cylindrical material as in the embodiment, but may be any other material (for example, a plate-like material, a rod-like material, a spherical material, etc.) depending on the application. ) Can of course be changed to At this time, the manufactured magnetic field molded body does not necessarily have to be a rotating body.

Similarly, the material of the substrate 4 can be changed to a material other than the alumina sintered body. For example,
Select ceramic sintered body other than alumina sintered body,
Further, it is also acceptable to select a material other than the ceramic sintered body (that is, a metal material, a resin material, or the like).

Magnetic powder 5 contained in resin molding material 2
May be other than the Sr ferrite exemplified in the embodiment, for example, Ba ferrite, Co ferrite, Pb ferrite, or the like. In addition, a polyamide resin other than nylon can be selected as the resin molding material 2, or a resin other than polyamide resin and having thermoplasticity can be selected.

According to the present invention, the base material 4 is provided in the cavity 31.
The same can be applied to the case where the magnetic field molding is performed using only the resin molding material 2 without inserting any.

As the first material, a stainless steel that is not austenitic and is not a magnetic material may be used, or an iron-based metal other than stainless steel that is not a magnetic material may be selected. Good. It is also acceptable to use a ceramic sintered body such as silicon carbide or silicon nitride as the non-magnetic material other than the metal. When such a ceramic sintered body is selected, the sub-mold piece 2
8 has the advantage that it can be formed with high precision.

The magnetized position in the anisotropic magnet 1 is not limited to the outer peripheral surface of the flange portion 3 but may be any other position (for example, the upper surface or the lower surface of the flange portion 3) depending on the application. You may.

The use of a material that is not a completely non-magnetic material as the first material to constitute the mold 21 is also permitted.
Specifically, a weak magnetic material may be used as the first material and a ferromagnetic material may be used as the second material. In the above embodiment, the anisotropic magnet 1 obtained by magnetizing a magnetic field molded product obtained through the injection molding method has been described as an example. Alternatively, an anisotropic magnet formed by magnetizing a magnetic field molded product obtained by a method other than injection molding may be used.

The first material does not necessarily have to be a part of the mold 21, and may be separate from the mold 21. Next, in addition to the technical idea described in the claims,
The technical ideas grasped by the above-described embodiments are listed below together with their effects.

(1) In a mold made of a magnetic material, a non-magnetic material is arranged at a location where magnetic field lines forming a magnetic field are likely to leak out of the cavity, and a resin molding material containing magnetic powder is supplied into the cavity. An anisotropic magnet manufactured through a molding method in which a magnetic field is applied to the cavity from a specific direction, wherein the anisotropic magnet is manufactured through a similar molding method under the condition that the non-magnetic material is not disposed at the location. Wherein the residual magnetic flux density in the region of the outer peripheral surface layer portion of the resin molding material constituting the anisotropic magnet is 1.5 to 2.0 times as compared with magnet.

(2) A magnetic field injection molded product manufactured by a molding method of applying a magnetic field from a specific direction to a cavity when supplying a resin molding material containing magnetic powder into a cavity of a mold, If the easy axis in the crystal of the magnetic powder is within ± 30 ° when defined as a good orientation state when the specific direction is used as a reference, the abundance ratio of the magnetic powder in the good orientation state is as follows: A magnetic field injection-molded article which is 75% or more in the region of the outer peripheral surface layer.

(3) Claims 1 to 4, technical idea 1,
In any one of 2, the thickness of the region of the outer peripheral surface portion is T / 2, where T is the width of the cavity along the direction of the magnetic field.

(4) In the technical idea of the fourth aspect, the resin molding material forms a rotationally symmetrical flange portion, and the flange portion is disposed on an outer peripheral surface of the rotationally symmetrical base material. An anisotropic magnet, wherein the outer peripheral surface of the flange portion is magnetized. Therefore, according to the invention described in the technical idea 4, it is possible to have a structure that can be used as, for example, a motor bearing member or the like.

[0059]

As described in detail above, according to the first to fourth aspects of the present invention, it is possible to provide an anisotropic magnet having a good orientation state and a strong magnetic force.

According to the third aspect of the present invention, it is possible to provide an anisotropic magnet suitable for use, for example, using a ceramic sintered body as a sliding portion. According to the fifth aspect of the present invention, it is possible to provide a manufacturing method capable of obtaining the above-described preferable anisotropic magnet without increasing the number of steps or increasing the cost.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an anisotropic magnet according to an embodiment of the invention.

FIG. 2 is a cross-sectional view showing the anisotropic magnet.

FIG. 3 is a schematic front view showing a main part of the magnetic field injection molding machine in the embodiment.

FIG. 4 is a sectional view of a mold for a magnetic field injection molding machine according to the embodiment.

5A is a view conceptually showing the orientation state of magnetic powder contained in a resin molding material in a portion where leakage of magnetic force lines is likely to occur, and FIG. FIG.

6A is a schematic cross-sectional view of an anisotropic magnet for explaining a comparative test method, FIG. 6B is a graph showing data of a comparative example, and FIG. 6C is a graph showing data of an example.

FIG. 7 is a cross-sectional view of a conventional mold for a magnetic field injection molding machine.

FIG. 8A is a diagram conceptually showing the orientation state of magnetic powder contained in a resin molding material in a portion where leakage of magnetic force lines is likely to occur, and FIG. FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Anisotropic magnet, 2 ... Resin molding material, 3b ... Outer peripheral surface, 4
... Base material, 5 ... Magnetic powder, 6 ... Easy magnetization axis, 31 ... Cavity, P1 ... Position where magnetic force lines easily leak out of the cavity,
T: width of cavity, A1: direction of magnetic field as specific direction.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B22F 5/12 B22F 5/00 B (72) Inventor Takashi Niwa 1-1-1 Ibigawa-cho, Ibi-gun, Ibi-gun, Gifu 4K018 CA04 CA16 GA04 HA04 JA16 KA46

Claims (5)

[Claims] 1. An anisotropic magnet manufactured by a molding method in which a magnetic field is applied from a specific direction to a cavity when a resin molding material containing magnetic powder is supplied into a cavity of a mold. When the direction of the magnetic powder in which the axis of easy magnetization in the crystal of the magnetic powder is within ± 30 ° with respect to the direction is defined as a good orientation state, the abundance ratio of the magnetic powder in the good orientation state is defined as An anisotropic magnet that is 75% or more in the surface surface layer region. 2. An anisotropic magnet manufactured by a molding method in which a magnetic field is applied from a specific direction to a cavity when a resin molding material containing magnetic powder is supplied into a cavity of a mold. In the case where the direction of the magnetic powder in which the axis of easy magnetization in the crystal of the magnetic powder is within ± 20 ° is defined as the good orientation state, the abundance ratio of the magnetic powder in the good orientation state is defined as An anisotropic magnet that is 50% or more in a surface layer region. 3. The anisotropic magnet according to claim 1, wherein the anisotropic magnet is formed by insert-molding a substrate made of a ceramic sintered body in the resin molding material. Sex magnet. 4. The anisotropic magnet according to claim 1, wherein the anisotropic magnet has a rotationally symmetric shape. 5. The method for manufacturing an anisotropic magnet according to claim 1, wherein the magnetic field lines forming the magnetic field leak out of the cavity in a mold made of a magnetic material. A method for manufacturing an anisotropic magnet, comprising: arranging a non-magnetic material at an easy place and applying a magnetic field to the cavity from a predetermined direction in that state.