JP2001274032A - Die device for manufacturing anisotropic multipolar plastic magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a die device which can manufacture an anisotropic multipolar plastic magnet having a stable magnetic characteristic. SOLUTION: In this die device in which a plurality of magnetic cores 15 formed of a ferromagnetic material and permanent magnets 16 are alternately arranged around a cavity 12 so that the magnetic poles of the magnets 16 become the same pole N or S on both sides of each core 15, the front end faces of the cavity-side end sections of the cores 15 are protruded toward the center of the cavity 12 and formed in a circular-arcuate shape along the periphery of the cavity 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold apparatus for producing an anisotropic multipolar plastic magnet by forming a plurality of magnetic poles by applying orientation to a molding material mixed with injected magnetic powder. Things.

[0002]

2. Description of the Related Art A conventional mold apparatus for producing this type of anisotropic multipolar plastic magnet is disclosed in, for example, Japanese Patent Application Laid-Open No. 64-32611.
As shown in FIG. 13, a magnetic core 1 and a permanent magnet 2 are alternately arranged around a non-magnetic annular member 3 as shown in FIG. 13, and a cavity 4 is formed in the non-magnetic annular member 3. The shaft member 5 is provided at the center of the cavity 4.
And injecting a molding material 6 in which a powder of a magnetic material and a resin as a binder are mixed through a plurality of injection ports (not shown), and orienting by a permanent magnet 2. Thus, as shown in FIG. 14, a plurality of magnetic poles 7 are formed around the shaft member 5 to obtain an anisotropic multipolar plastic magnet 10 functioning as a magnet rotor.

[0003]

The conventional mold apparatus for producing anisotropic multipolar plastic magnets is constructed as described above. As a result of measuring the magnetic flux density distribution in the cavity 4,
A waveform characteristic as shown by a curve A in FIG. 15 was obtained. However, as is apparent from the figure, a large protrusion is generated near the upper and lower limits of the waveform, and a waveform far from the sine wave shown by the curve B in FIG. The strongest magnetic field is required, and a sine wave must be obtained by attenuating sequentially toward both ends. However, since the shape of the tip surface of the magnetic core 1 is flat, at a position slightly away from the center, This is considered to be due to the fact that the magnetic field and strength at the central portion did not change much, and the magnetic characteristics of the anisotropic multipolar plastic magnet 10 obtained in the cavity 4 varied, resulting in cogging torque and vibration and noise. There was a problem that it might be the cause.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide a mold apparatus for producing an anisotropic multipolar plastic magnet capable of obtaining sufficient magnetic characteristics. It is assumed that.

[0005]

According to a first aspect of the present invention, there is provided a mold apparatus for manufacturing an anisotropic multipolar plastic magnet, comprising: a plurality of magnetic cores formed of a ferromagnetic member around a cavity; However, in a mold apparatus for producing anisotropic multipolar plastic magnets in which the poles of the permanent magnet are alternately arranged so that the poles are the same on both sides of the magnetic core, the tip surface of the cavity side end of the magnetic core is It protrudes toward the center and is formed in an arc shape extending along the circumferential direction.

According to a second aspect of the present invention, a mold apparatus for manufacturing an anisotropic multipolar plastic magnet includes a magnetic core formed of a ferromagnetic member at an end on a cavity side around a cavity. A plurality of permanent magnets are arranged radially at predetermined intervals so that adjacent poles alternately have different poles, and connect the ends of the permanent magnets on the side different from the magnetic core. In the mold apparatus for manufacturing an anisotropic multipolar plastic magnet provided with an annular back yoke formed in the above, a tip end surface of a cavity side end of a magnetic core protrudes toward the center side of the cavity and has an arc shape along a circumferential direction. It is formed in.

According to a third aspect of the present invention, in the mold apparatus for manufacturing an anisotropic multipolar plastic magnet according to the first aspect, the width of the magnetic core is smaller than the width of the end on the cavity side. Things.

According to a fourth aspect of the present invention, there is provided a mold apparatus for manufacturing an anisotropic multipolar plastic magnet.
In any one of the above, when the diameter of the cavity is D and the number of poles of the anisotropic multipolar plastic magnet is n, the width W of the cavity-side end of the magnetic core and the circle of the cavity-side end of the magnetic core are The radius of curvature R of the arc of the arc-shaped tip surface is set to a value of the following formula: W = 1.9 to 2.7 × D / n R = 1.2 to 2.1 × D / n is there.

The mold apparatus for producing anisotropic multipolar plastic magnet according to claim 5 of the present invention is described in claims 1 to 3.
In any one of the above, the height of the magnetic core and the permanent magnet is larger than the depth of the cavity, and the magnetic core and the permanent magnet are formed to protrude outward from both sides in the depth direction of the cavity.

The mold apparatus for producing anisotropic multipolar plastic magnet according to claim 6 of the present invention is described in claims 1 to 3.
In either of the above, the upper and lower surfaces near the cavity side end of the magnetic core are inclined toward the center of the cavity toward the tip.

Further, the mold apparatus for manufacturing an anisotropic multipolar plastic magnet according to claim 7 of the present invention is described in claims 1 to 6.
In any one of the above, a cavity ring having a predetermined inner shape and formed of a non-magnetic member is arranged on an outer peripheral portion of the cavity.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a plan view showing a configuration of a main part of a mold apparatus for manufacturing an anisotropic multipolar plastic magnet according to Embodiment 1 of the present invention, and FIG. 2 shows a configuration of a main part of the manufacture mold apparatus in FIG. FIG. 3 is a perspective view, FIG. 3 is a plan view showing the distribution of magnetic flux in the manufacturing mold apparatus in FIG. 1,
FIG. 4 is a waveform diagram showing the distribution characteristics of the magnetic flux density in the manufacturing mold apparatus in FIG.

In FIG. 1, reference numeral 11 denotes a cavity ring formed of a non-magnetic member and defining a cavity 12 inside.
An arc-shaped contact surface 11a having a predetermined radius of curvature is formed on the outer peripheral surface at a predetermined interval. Reference numeral 13 denotes a shaft member disposed at the center of the cavity 12, and reference numeral 14 denotes a molding material filled between the shaft member 13 and the cavity ring 11, which is produced by mixing powder of a magnetic member and a resin as a binder. ing. Reference numeral 15 denotes a tip surface 1 formed of a ferromagnetic member and formed in an arc shape at an end on the cavity side.
Reference numeral 5a denotes a plurality of magnetic cores which are in contact with the contact surface 11a of the cavity ring 11 and are arranged radially.

The width dimension W of the cavity side end of the magnetic core 15 and the arc-shaped tip surface 1 of the cavity side end are defined.
The radius of curvature R of the circular arc 5a is as follows, where D is the diameter of the cavity 12 (the inner diameter of the cavity ring 11), and n is the number of poles of the anisotropic multipolar plastic magnet formed in the cavity. , (2). W = 1.9 to 2.7 × D / n (1) R = 1.2 to 2.1 × D / n (2) 16 is inserted between the magnetic cores 15 and The plurality of permanent magnets are arranged alternately such that the poles are the same on both sides of the magnetic core 15. These 11, 15, and 16 are mounted in a mold main body (not shown) to constitute a manufacturing mold apparatus.

In the manufacturing die apparatus according to the first embodiment configured as described above, the magnetic field generated by each permanent magnet 16 is distributed as shown in FIG. The formed molding material is oriented, and the magnetic core 1 sandwiched between the N poles of the two permanent magnets 16 is used.
5 is magnetized to the S pole, and the portion of the magnetic core 15 sandwiched between the S poles of both permanent magnets 16 is magnetized to the N pole. Thus, an anisotropic multipolar plastic magnet having the same number of poles as the magnetic core 15 is formed.

As described above, according to the first embodiment, since the tip end surface 15a of the cavity-side end of each magnetic core 15 is formed in an arc shape, the magnetic field at the center becomes strongest toward both ends. Since the direction of the magnetic field is gradually bent away from the center, the magnetic field is sequentially attenuated to obtain a sinusoidal waveform, and the magnetic properties of the anisotropic multipolar plastic magnet are stabilized, and cogging torque is generated. The situation of causing vibration and noise is eliminated.

Further, the width W of the cavity-side end of the magnetic core 15 and the arc-shaped tip surface 1 of the cavity-side end are defined.
By setting the value of the radius of curvature R of the arc 5a to the value of the above formulas (1) and (2), it is possible to further improve the magnetic characteristics. That is, FIG. 4 shows that the diameter of the cavity 12, that is, the diameter of the anisotropic multipolar plastic magnet is 49 mm, the number of poles n is 8, and the tip surface 1 of the magnetic core 15 is
The dimensions of the radius of curvature R of the arc 5a are 5 mm, 10 mm, and 1 mm.
5 shows the waveform of the magnetic flux density distribution in the case of 5 mm, and compares it with the waveform of R = 10 mm included in the range of the equation (2) shown by the curve A in FIG. It is clear that the waveforms in the case of R = 5 mm and R = 15 mm indicated by C have sharp upper and lower limits and are dull, respectively, and have poor magnetic properties.

Embodiment 2 FIG. FIG. 5 is a plan view showing a configuration of a main part of a mold apparatus for manufacturing an anisotropic multipolar plastic magnet according to Embodiment 2 of the present invention. In the figure, the same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. Numeral 17 denotes a plurality of magnetic cores which are formed of a ferromagnetic member and whose radially arranged tip surfaces 17a at the cavity side end abut against the contact surface 11a of the cavity ring 11, and which are radially arranged. Is the same as that in the first embodiment, but the width W ₁ of the portion sandwiched between the permanent magnets described later is smaller than the width W of the cavity side end. . Numeral 18 denotes a plurality of permanent magnets inserted between the magnetic cores 17 and arranged alternately so that the poles are the same on both sides of the magnetic core 17. These 11, 17, and 18 are mounted in a mold main body (not shown) to constitute a manufacturing mold apparatus.

As described above, according to the second embodiment, the tip end face 17a of the magnetic core 17 at the cavity side is formed in an arc shape, and the width W ₁ of the portion sandwiched by the permanent magnets 18 is reduced. Since it is formed smaller than the width dimension W of the cavity-side end, the magnetic properties of the anisotropic multipolar plastic magnet can be stabilized as in the first embodiment. the order of the width W ₁ of the site that was nipped thereby increasing the width dimension of the permanent magnet by the amount formed in a small, it is possible to generate a larger magnetic field to expand the magnetic path cross-sectional area, different It is possible to enhance the magnetic properties of the isotropic multipolar plastic magnet.

Embodiment 3 FIG. 6 is a plan view showing a configuration of a main part of a mold apparatus for manufacturing an anisotropic multipolar plastic magnet according to Embodiment 3 of the present invention, and FIG. 7 shows a configuration of a main part of the manufacture mold apparatus in FIG. FIG. 8 is a plan view showing a magnetic flux distribution in the manufacturing mold apparatus in FIG. In the figure, reference numeral 19 denotes a cavity ring formed of a non-magnetic member and defining a cavity 20 inside, and an arc-shaped contact surface 1 having a predetermined radius of curvature on an outer peripheral surface at a predetermined interval.
9a are formed. Reference numeral 21 denotes a shaft member arranged at the center of the cavity 20, and reference numeral 22 denotes a molding material filled between the shaft member 21 and the cavity ring 19, which is produced by mixing powder of a magnetic member and a resin as a binder. ing. Numeral 23 denotes a plurality of magnetic cores which are formed of a ferromagnetic member and whose radially arranged tip surfaces 23a at the cavity side end portions are in contact with the contact surface 19a of the cavity ring 19 and are arranged radially.

A plurality of permanent magnets 24 are radially connected to an end face of the magnetic core 23 on a side different from the tip end face 23a, and are arranged so that poles adjacent to each other in the circumferential direction are alternately different in polarity. , 25 are annular back yokes made of a ferromagnetic member so as to connect the ends of the permanent magnets 24 on the side different from the magnetic core 23.
Reference numeral 25 is mounted in a mold body (not shown) to constitute a manufacturing mold apparatus. The width W of the cavity-side end of the magnetic core 23 and the radius of curvature R of the arc of the distal end surface 23a of the magnetic core 23 are calculated by the equations (1) and (2) as described in the first embodiment. ) Are set to the values shown in FIG.

As described above, according to the third embodiment, as in the first embodiment, the tip surface 23a of the end of each magnetic core 23 on the cavity side is formed in an arc shape.
As the magnetic field at the center is strongest toward both ends, the direction of the magnetic field is gradually bent away from the center, so that the magnetic field is sequentially attenuated to obtain a sinusoidal waveform and an anisotropic multipolar plastic magnet The magnetic characteristics of the magnetic core 23 are stable, cogging torque is generated, vibration and noise are eliminated, and the width W of the cavity end of the magnetic core 23 and the circle of the cavity end are eliminated. By setting the value of the radius of curvature R of the arc of the arc-shaped tip surface 23a to the value of the above formulas (1) and (2), it is possible to further improve the magnetic characteristics.

Embodiment 4 FIG. 9 is a perspective view showing a configuration of a main part of a mold apparatus for manufacturing an anisotropic multipolar plastic magnet according to Embodiment 4 of the present invention, and FIG. 10 is an anisotropic multipolar plastic according to Embodiment 4 of the present invention. FIG. 10 is a perspective view illustrating a configuration of a main part of a mold apparatus for manufacturing a magnet, which is different from FIG. 9. In the fourth embodiment, as shown in FIG. 9, the height of the magnetic core 15 and the permanent magnet 16 is formed to be larger than the depth of the cavity 12, that is, the height of the cavity ring 11. The points formed projecting outward from both ends in the depth direction as shown in FIG.
Other configurations are the same except for the difference from the first embodiment.

As described above, according to the fourth embodiment, the height of the magnetic core 15 and the permanent magnet 16 is
2 is formed so as to protrude outward from both ends in the depth direction of the cavity 12, so that the magnetic field existing near both ends in the height direction of the magnetic core 15 can be reduced. Since a weak region can be avoided from a position corresponding to a region where a molding material (not shown) is oriented in the cavity 12, stable orientation can be obtained and magnetic characteristics can be improved. .

In the above configuration, the manufacturing die apparatus according to the first embodiment has been described as an example, but the present invention may be applied to the manufacturing die apparatus according to the second embodiment as shown in FIG. The height of the permanent magnet 18 is
It is needless to say that the same effect as described above can be exerted even if it is formed so as to be larger than the depth dimension of No. 2 and protrude outward from both ends in the depth direction of the cavity 12.

Embodiment 5 FIG. 11 is a perspective view showing a configuration of a main part of a mold apparatus for manufacturing an anisotropic multipolar plastic magnet according to Embodiment 5 of the present invention, and FIG. 12 is an anisotropic multipolar plastic according to Embodiment 5 of the present invention. FIG. 12 is a perspective view illustrating a configuration of a main part of a mold apparatus for manufacturing a magnet, which is different from FIG. 11. In the fifth embodiment, as shown in FIGS. 11 and 12, both upper and lower surfaces near the ends of the magnetic cores 15 and 17 near the cavity are inclined toward the center of the cavity 12 toward the tip, and the inclined surfaces 15a and 17b is provided.
The other configuration is the same except for the difference from the fourth embodiment.

As described above, according to the fifth embodiment, the upper and lower surfaces near the cavity-side end of each of the magnetic cores 15 and 17 are
Since the inclined surfaces 15a and 17a are provided to be inclined toward the center of the cavity 12 toward the front end, the magnetic core 1
Since the direction of the magnetic field near both ends in the height direction of 5, 17 is inclined toward the center of the cavity by the inclination of the inclined surfaces 15a, 17a, the strength of the magnetic field in the cavity 12 can be increased by that amount. As a result, a stable orientation can be obtained and the magnetic characteristics can be improved.

In the above configuration, the manufacturing mold apparatus according to the fourth embodiment has been described as an example. However, for example, the manufacturing mold apparatus according to the first embodiment, that is, the depth dimension of the cavity 12, the magnetic core 15, and the permanent magnet It is needless to say that the same height may be applied to those having the same height dimension, and the same effect as described above can be exerted. Although not described in each of the above configurations, a cavity ring 11 for partitioning the cavity 12 is provided, and the inner surface of the cavity ring 11 is formed in a predetermined shape, thereby providing an anisotropic material having a desired outer shape. It is possible to obtain a multipolar plastic magnet.

[0029]

As described above, according to the first aspect of the present invention, the plurality of magnetic cores formed of ferromagnetic members and the permanent magnets around the cavity have the poles of the permanent magnets on both sides of the magnetic core. In the mold apparatus for manufacturing anisotropic multipolar plastic magnets which are alternately arranged so as to have the same polarity, the tip surface of the end of the magnetic core on the cavity side protrudes toward the center of the cavity and extends along the circumferential direction. Since it is formed in an arc shape, it is possible to provide a manufacturing mold apparatus capable of obtaining an anisotropic multipolar plastic magnet having stable magnetic properties.

According to the second aspect of the present invention, a plurality of permanent magnets each having a magnetic core formed of a ferromagnetic member at the end on the cavity side around the cavity are formed radially at predetermined intervals. And an annular back yoke formed so that adjacent poles are alternately different in polarity and connected to ends of the permanent magnets on a side different from the magnetic core. In the mold apparatus for manufacturing anisotropic multipolar plastic magnets, the tip end surface of the cavity side end of the magnetic core protrudes toward the center of the cavity and is formed in an arc shape along the circumferential direction, so that the magnetic characteristics are stable and anisotropic. The manufacturing die apparatus which can obtain a flexible multipolar plastic magnet can be provided.

According to a third aspect of the present invention, in the first aspect, the width of the magnetic core is formed to be smaller than the width of the end on the cavity side, so that the magnetic field is enhanced and the magnetic characteristics are stabilized. It is possible to provide a production mold apparatus capable of obtaining a modified anisotropic multipolar plastic magnet.

According to a fourth aspect of the present invention, in any one of the first to third aspects, when the diameter of the cavity is D and the number of poles of the anisotropic multipolar plastic magnet is n, The width dimension W of the cavity side end of the core and the radius of curvature R of the arc of the arc-shaped tip surface of the cavity side end of the magnetic core are expressed by the following formula: W = 1.9 to 2.7 × D / n R = 1.2 to 2.1 × D / n, so that the magnetic field distribution can be made sinusoidal so that an anisotropic multipolar plastic magnet with more stable magnetic properties can be obtained. Can be provided.

According to a fifth aspect of the present invention, in any one of the first to third aspects, the height of the magnetic core and the permanent magnet is made larger than the depth of the cavity so that the magnetic core and the permanent magnet are separated. Since it is formed to protrude outward from both sides in the depth direction of the cavity, it is possible to provide a manufacturing mold apparatus capable of obtaining an anisotropic multipolar plastic magnet having stable magnetic properties.

According to the sixth aspect of the present invention, in any one of the first to third aspects, the upper and lower surfaces near the cavity side end of the magnetic core are inclined toward the center of the cavity toward the tip. In addition, it is possible to provide a production mold apparatus capable of obtaining an anisotropic multipolar plastic magnet having an enhanced magnetic field and further having stable magnetic properties.

According to a seventh aspect of the present invention, in any one of the first to sixth aspects, a cavity ring having a predetermined inner shape and formed of a non-magnetic member is disposed on an outer peripheral portion of the cavity. Thus, it is possible to provide a manufacturing mold apparatus capable of obtaining an anisotropic multipolar plastic magnet having a desired external shape.

[Brief description of the drawings]

FIG. 1 is a plan view showing a configuration of a main part of a mold apparatus for manufacturing an anisotropic multipolar plastic magnet according to Embodiment 1 of the present invention.

FIG. 2 is a perspective view showing a configuration of a main part of the manufacturing mold apparatus in FIG.

FIG. 3 is a plan view showing the distribution of magnetic flux in the manufacturing mold apparatus in FIG.

4 is a waveform diagram showing distribution characteristics of a magnetic flux density in the manufacturing mold apparatus in FIG.

FIG. 5 is a plan view showing a configuration of a main part of a mold apparatus for manufacturing an anisotropic multipolar plastic magnet according to Embodiment 2 of the present invention.

FIG. 6 is a plan view showing a configuration of a main part of a mold apparatus for manufacturing an anisotropic multipolar plastic magnet according to Embodiment 3 of the present invention.

7 is a perspective view showing a configuration of a main part of the manufacturing mold apparatus in FIG. 6;

8 is a plan view showing the distribution of magnetic flux in the manufacturing mold apparatus in FIG.

FIG. 9 is a perspective view showing a configuration of a main part of a mold apparatus for manufacturing an anisotropic multipolar plastic magnet according to Embodiment 4 of the present invention.

FIG. 10 is a perspective view showing a configuration of a main part of a mold apparatus for manufacturing an anisotropic multipolar plastic magnet according to Embodiment 4 of the present invention, which is different from FIG. 9;

FIG. 11 is a perspective view showing a configuration of a main part of a mold apparatus for manufacturing an anisotropic multipolar plastic magnet according to Embodiment 5 of the present invention.

FIG. 12 is a perspective view showing a configuration of a main part of a mold apparatus for manufacturing an anisotropic multipolar plastic magnet according to Embodiment 5 of the present invention, which is different from FIG. 11;

FIG. 13 is a plan view showing a configuration of a conventional mold apparatus for producing an anisotropic multipolar plastic magnet.

FIG. 14 is a perspective view showing a configuration of an anisotropic multipolar plastic magnet obtained by the manufacturing mold apparatus in FIG.

FIG. 15 is a waveform diagram showing distribution characteristics of magnetic flux density in the manufacturing mold apparatus in FIG. 13 in comparison with ideal distribution characteristics.

[Explanation of symbols]

11, 19 cavity ring, 11a, 19a contact surface, 12, 20 cavity, 13, 21 shaft member, 1
4,22 Molding material, 15,17,23 Magnetic core, 15
a, 17a Inclined surface, 23a Tip surface, 16, 18, 2
4 permanent magnets, 25 back yoke.

Claims (7)

[Claims] A plurality of magnetic cores and permanent magnets formed of a ferromagnetic member are alternately arranged around a cavity such that the poles of the permanent magnets are the same on both sides of the magnetic core. In a mold apparatus for producing an isotropic multipolar plastic magnet, a tip end surface of a cavity side end of the magnetic core is formed to protrude toward a center of the cavity and to be formed in an arc shape along a circumferential direction. Mold equipment for manufacturing flexible multipolar plastic magnets. 2. A plurality of permanent magnets each having a magnetic core formed of a ferromagnetic member at an end on the cavity side around a cavity, and alternately radiating and adjacent poles at predetermined intervals. And an anisotropic multi-polar plastic magnet having an annular back yoke formed so as to connect ends of the respective permanent magnets on a side different from the magnetic core. In a manufacturing mold apparatus, a tip end surface of a cavity side end of the magnetic core protrudes toward a center side of the cavity and is formed in an arc shape along a circumferential direction. Mold equipment. 3. The mold apparatus for producing anisotropic multipolar plastic magnet according to claim 1, wherein the width of the magnetic core is smaller than the width of the end on the cavity side. 4. When the diameter of the cavity is D and the number of poles of the anisotropic multipolar plastic magnet is n, the width W of the end of the magnetic core on the cavity side and the width of the end of the magnetic core on the cavity side are determined. The radius of curvature R of the arc of the arc-shaped tip surface is set to a value of the following equation: W = 1.9 to 2.7 × D / n R = 1.2 to 2.1 × D / n The mold apparatus for producing an anisotropic multipolar plastic magnet according to any one of claims 1 to 3, wherein: 5. The magnetic core and the permanent magnet are formed by making the height dimension of the magnetic core and the permanent magnet larger than the depth dimension of the cavity and projecting the magnetic core and the permanent magnet outward from both sides in the depth direction of the cavity. A mold apparatus for producing an anisotropic multipolar plastic magnet according to any one of claims 1 to 3. 6. The anisotropic poly according to claim 1, wherein the upper and lower surfaces of the magnetic core near the cavity side end are inclined toward the center of the cavity toward the tip. Manufacturing equipment for polar plastic magnets. 7. The anisotropic member according to claim 1, wherein a cavity ring having a predetermined inner shape and formed of a non-magnetic member is disposed on an outer peripheral portion of the cavity. Mold equipment for manufacturing flexible multipolar plastic magnets.