JPH0624175B2 - Method for manufacturing ring-shaped magnetic compact - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a cylindrical magnet magnetized in multiple poles in the radial direction, particularly a resin composition ring-shaped magnetic molded body containing magnetic powder. .

[Conventional technology]

Ring magnets with multiple poles in the radial direction are widely used in various applications including small motors. In order to manufacture a high-performance ring-shaped magnet with multiple poles in the radial direction, in the process of molding magnetic powder into a ring shape,
It is desirable that the magnetic powder be oriented in the radial direction to form a ring-shaped magnetic compact having magnetic anisotropy. Then, the more uniform the orientation of the magnetic powder, the more excellent the magnetic properties of the magnet can be obtained. The specification of Japanese Patent Application No. 58-54139 discloses an industrially advantageous method for producing a ring-shaped magnetic compact in which the orientation of such magnetic powder is aligned in the radial direction.

[Problems to be solved by the invention]

Generally, a method for manufacturing a multi-pole radial ring-shaped magnet is to orient magnetic particles in the radial direction, demagnetize once and then magnetize to a desired number of poles to form a ring-shaped magnet. There is a limit to the length of the molded body. This is because the cross section of the passage of the magnetic flux passing through the ring-shaped magnetic molded body and then drawn out during orientation is determined by the inner diameter cross-sectional area of the ring-shaped magnetic molded body and cannot be increased. Generally, the length of the ring-shaped magnetic molded body is limited to about 50% of the inner diameter, although it depends on the magnitude of the radial orientation magnetic field. Performance is degraded because it is not done. When designing a multi-pole motor that is long in the axial direction, a number of cylindrical magnets are packed together in the axial direction, or long C-shaped segment magnets are bonded together. Further, when it was absolutely necessary to use a magnet with a cylindrical integral body, a magnet with low performance with no orientation had to be used. Japanese Patent Application No. 59-42269 discloses a method of manufacturing a radial multipole ring-shaped magnet by a method in which there is substantially no limitation on the cylindrical length.

This manufacturing method has a problem that it can be applied when the peripheral lengths of the cavities of the first and second magnetic members are the same, but cannot be applied when they are different.

The present invention has been made to solve the above problems, and an object thereof is to provide a method for manufacturing a ring-shaped magnetic molded body in which the areas of the N pole and the S pole are different.

[Means for solving problems]

In the method for manufacturing a ring-shaped magnetic molded body according to the present invention, first, a mold including an inner mold and an outer mold is formed, and a hole provided in the outer mold and a large relative magnetic permeability inserted in the hole are formed. A ring-shaped cavity is formed with an inner mold made of a material, and the outer wall of the cavity is composed of a plurality of first magnetic members having a large relative magnetic permeability and the same number of first magnetic members as the outer peripheral portion of the cavity. With a molding device configured by alternately arranging second magnetic members having different relative lengths and large relative magnetic permeability in an annular shape,
A magnet composition containing magnetic powder is filled in the cavity so that the magnetic powder can be displaced, and the outer die, the magnet composition and the inner die are magnetically coupled to each other, and a current is passed through the solenoid coil. A polar orientation is caused in the powder, and then the magnet composition is solidified to obtain a ring-shaped magnetic molded body.

[Action]

In the present invention, since the circumferential lengths of the cavities of the first and second magnetic members are different, the N pole and the S pole are different.
A ring-shaped magnetic molded body having a different area from the pole can be obtained.

〔Example〕

The present invention is based on the previously proposed method for producing a ring-shaped magnetic molded body of Japanese Patent Application No. 59-42269. Therefore, before explaining the embodiments of the present invention, the previously proposed invention Will be described.

FIG. 4 is a layout of the solenoid coil, the first magnetic member, the second magnetic member, the non-magnetic member, and the inner mold forming the outer mold of the molding device used in the method of manufacturing the ring-shaped magnetic molded body proposed above. The relationship is shown, and the cross section perpendicular to the central axis of the cavity of the molding apparatus, that is, II in FIG.
It corresponds to a sectional view taken along a line. FIG. 5 corresponds to a sectional view taken along line II-II in FIG. In the figure, 1 is a pole piece, 2
Is a solenoid coil surrounding it, 3 is a first magnetic member that is in contact with the pole piece 1 at its end and is magnetically coupled to it, 4 is an inner mold, 5 is a second magnetic member, 6 Is a non-magnetic member, and 7 is a ring-shaped cavity. (The previously proposed invention is characterized by the mutual magnetic shape of the parts of the molding machine used, and therefore means for supplying the magnet composition to the cavity 7 and means for removing the compact from the cavity 7). Since the mechanical structure of the molding device such as the above may be based on a known one, it is omitted in the figure).
The outer mold facing the inner mold 4 is composed of members mainly composed of the first and second magnetic members 3 and 5. The first magnetic member 3 and the second magnetic member 5 are alternately arranged in an annular shape around the cavities 7 so as to form an outer wall of the cavities 7, and between the respective magnetic members 3 and 5. Magnetic member 3,
A non-magnetic member 6 is interposed in order to cut off the magnetic coupling of 5. In FIG. 4, a part of the outer wall of the cavity 7 is formed of the non-magnetic member 6 so that the first magnetic member 3 and the second magnetic member 5 do not come into physical contact with each other. If desired, the first magnetic member 3 and the second magnetic member 5 are brought into contact with each other at both ends of the portion facing the cavity 7, and the outer wall of the cavity 7 is made into contact with the first and second magnetic members 3. , 5 can also be used. Even if the first and second magnetic members 3 and 5 are in contact with each other at their ends, this portion is immediately magnetically saturated, and the magnetic flux passing therethrough is small and can be almost ignored.

In order to produce a polar-oriented ring-shaped magnetic compact using the apparatus shown in FIG. 4, first, the cavity 7 is filled with a magnet composition so that the magnetic powder can be displaced, that is, its position and attitude can be changed. Although any magnetic powder such as ferrite can be used as the magnetic powder, an alloy containing a rare earth element such as a samarium-cobalt alloy that provides a high-performance magnet is preferable.
8K is required to cause the powder of such an alloy to have a sufficient orientation.
Although the strength of the spatial magnetic field equal to or higher than Oe is required, this method can easily generate such a strong magnetic field in the cavity 7.

After charging the magnet composition into the cavity 7, when a reverse current is passed through the left and right solenoid coils 2, the pole pieces 1 move to the first magnetic member 3 in contact therewith or in the opposite direction. A magnetic field is generated. The first and second magnetic members 3, 5 and the inner mold 4 and the composition for a magnet differ greatly in relative magnetic permeability, and the first and second magnetic members 3,
Since 5 is magnetically blocked by the non-magnetic member 6,
A magnetic flux flows in the order of the pole piece 1 → the first magnetic member 3 → the magnet composition in the cavity 7 → the inner mold 4 → the magnet composition in the cavity 7 → the second magnetic member 5 or in the opposite direction, The magnetic powder of the magnet composition in the cavity 7 is oriented in this direction. When the composition is solidified when the orientation is completed, an extremely oriented body is obtained. It is needless to say that the current may be supplied to the solenoid coil 2 before the cavity 7 is filled with the magnet composition.

In the above description, when the magnetic flux passing through the cavity 7 does not form a closed circuit, that is, when the end of the second magnetic member 5 is not magnetically coupled to the pole piece 1, the second magnetic It is preferable to guide the magnetic flux as far as possible by the second magnetic member 5 so that the leakage of the magnetic flux from the end of the member 5 does not affect the magnetic field of the cavity 7 as much as possible. In the apparatus of FIG. 4, the second magnetic member 5 is elongated in consideration of this point. Generally, the end of the second magnetic member 5 may be brought to a position separated from the cavity 7 by 2 to 5 times the diameter of the cavity 7.

Further, it is necessary to concentrate the magnetic flux on the cavity 7 as much as possible. For this purpose, it is preferable to make the thickness of the first and second magnetic members 3, 5 thicker than the height of the cavity 7 and to incline toward the cavity 7 from both upper and lower sides. As shown in FIG. 5, both ends of the first magnetic member 3 are formed obliquely toward the cavity 7 (the end of the second magnetic member 5 is not shown in the drawing). And the same shape). It is preferable that the thickness of each magnetic member 3 and 5 is at least twice as high as the height of the cavity 7, especially at least three times. In FIG. 5, 8 is the above-mentioned cavity 7.
Similarly, the upper bottom 9 is the lower bottom, and like the outer non-magnetic member 6, is made of a material having a small relative magnetic permeability, for example, a non-magnetic material such as beryllium copper.

Although FIG. 4 and FIG. 5 show an apparatus for producing a four-pole molded body, it is also possible to produce a multi-pole molded body.
For example, FIG. 6 shows a solenoid coil 2 which is an example of an apparatus for producing a 6-pole molded body, a first magnetic member 3, a second magnetic member 5 and a non-magnetic member 6 which form an outer die, and an inner die 4. FIG. 4 is a diagram conceptually showing the arrangement relationship of No. 4 and corresponds to FIG. 4 in the case of four poles. In FIG. 6, the second magnetic member 5 extends long in the up-down direction of the cavity 7 as shown in FIG. 7 (a), and the leakage of the magnetic field from the end of the cavity 7 causes the magnetic field of the cavity 7. It is configured to have no effect. 7 (a) and 7 (b) are sectional views taken along lines III-III and IV-IV in FIG.

The above method is an example in which a mold having one cavity 7 is used, but it is preferably performed using a mold having a plurality of cavities 7 in order to improve productivity. Fig. 8 shows the fourth
Similar to FIG. 6 and FIG. 6, an example of the solenoid coil 2 in the case of using the mold having the plurality of cavities 7, the first magnetic member 3, the second magnetic member 5 and the non-magnetic member constituting the outer mold The magnetic member 6 and the inner mold | type 4 are shown in a positional relationship, and correspond to the sectional view which follows the VV line of FIG. 9 and 10 are VI-VI of FIG. 8, respectively.
Line, which corresponds to a sectional view taken along the line VII-VII. In these drawings, the respective second magnetic members 5 existing between the two cavities 7 are combined into one magnetic member, but if desired, this is a member dedicated to each cavities 7. It is also possible to separate. Also each cavities 7
The first magnetic members 3 are separately connected to the pole piece 1, but they may be collectively connected to the pole piece 1. Further, the second magnetic member 5 also extends in the vertical direction of the cavity 7 as shown in FIG. 9 also in this case. In general, the diameter of the cavity 7 is more than twice the diameter of the cavity 7 from the top bottom 8 and bottom bottom 9 of the cavity 7, respectively.
It is preferably projected 2 to 5 times. FIGS. 9 and 10 show that the first magnetic member 3 and the second magnetic member 5 are formed such that their ends are inclined toward the cavity 7 so that the magnetic flux concentrates on the cavity 7. Has become.
Behind the upper bottom 8 and the lower bottom 9, respectively, are backing materials 11 and 12 made of a non-magnetic material.
Are arranged to maintain the mechanical strength of the mold. In FIGS. 9 and 10, the second magnetic member 5 is magnetically coupled to each other at the upper and lower ends thereof by the magnetic members 10 connecting them, and the leakage of magnetic flux affects the cavity 7. The impact is reduced.

In this method, in the cavity 7, the magnetic flux can be transferred from the first magnetic member 3 of the outer die to the inner die 4 and from the inner die 4 to the second magnetic member 5 of the outer die, or vice versa. It is important to be perfectly oriented. One means for achieving this is to increase the relative magnetic permeability of the magnetic member forming the cavity 7 as compared with the magnet composition in the cavity 7. Usually 3 for magnet composition
A material having a relative magnetic permeability of 0 times or more is used. From the viewpoint of the orientation of the magnetic powder, the larger the ratio, the better. However, industrially usable materials have a relative magnetic permeability of at most 10 ⁵
At present, it is difficult to entirely use such a material having a high relative magnetic permeability as a magnetic material. At present, a magnetic material having a relative magnetic permeability of about 500 can be used as a magnetic material for producing a mold, from the viewpoint of strength, hardness, workability, etc., and the relative magnetic permeability is usually 80 to 20.
Although about 0 SKD material is used, the mold of the above method can also be manufactured with such a material.

As an example of the magnetic field of the cavity 7 in the above,
A magnetic material with a width of about 28 m / m, a height of 80 m / m, and a length of 30 m / m (relative permeability of about 100, maximum saturation magnetic flux density of about 17K
G) 4 pieces are prepared, and one end of each is 39.5m in diameter.
Processing was performed so as to form a circular arc of / m, and further, a straight line portion having a length of 40 m / m was left in the central portion, and was obliquely cut from both upper and lower surfaces at an angle of 45 °. Separately, a magnetic material with a diameter of 35.
A column having a length of 5 m / m and a length of 40 m / m was manufactured. On the wooden pedestal 13, the four members manufactured above are 39.5 mm in diameter.
The outer mold was arranged in an annular shape of m / m, and the cylinder manufactured as described above was arranged in the center of the outer mold, and the inner mold 4 was used as a mold model. In the middle of the solenoid coil 2 having the pole piece 1, the first magnetic member 3 and the pole piece 1
The first magnetic member 3 was arranged so as to come into contact with the first magnetic member 3 and at a position about 1/4 from the end of the pole piece 1 (see FIGS. 11 and 12). The second magnetic member 5
The end portion of (1) was connected to the other end of the pole piece 1 by another magnetic member to form a magnetic closed circuit. 3 to solenoid coil 2
A magnetic field in the radial direction in the illustrated portion of the cavity 7 was measured by passing a current of 0000 (AT). The results are shown in Table 1 below.

In addition, in the value of the strength of the magnetic field, + indicates outward in the radial direction, − indicates inward, and the arrow in FIG. 11 indicates the direction of the magnetic field. As is clear from this measurement result, the strength of the magnetic field in each portion of the cavity 7 is substantially uniform, and therefore, the magnetic powder in the magnet composition filled in the cavity 7 is required to cause uniform and sufficient polar orientation. You can Further, since there is no limitation on the depth of the cavity 7 in terms of magnetic characteristics, it is advantageous for manufacturing a long cylindrical magnet.

Measurement location Magnetic field strength (KG) A-x +13.7 A'-X +12.4 B-X-14.3 B'-X-12.2 A-Y +14.0 A'-Y +12.5 B-Y-14.5 B'-Y-12.3 Table 1 A ring-shaped magnetic molded body having an axially unlimited length is obtained as described above. By the way, in the molding apparatus of FIG. 4 described above, the first magnetic member 3 and the second magnetic member 5 are used.
Is a mold structure having the same peripheral length on the outer peripheral portion of the cavity 7, and therefore it is not possible to obtain a ring-shaped magnetic molded body in which the areas of the N pole and the S pole are different.

In order to solve this problem, the present invention uses the molding apparatus having the configuration shown in FIG. In the case of FIG. 4 described above, the upper and lower ends of the inner mold 4 are usually aligned with the upper and lower surfaces 8 and 9 of the cavity 7. However, in the present invention, since the circumferential lengths of the first and second magnetic members 3 and 5 at the outer peripheral portions of the cavity 7 are different, considering the balance of the magnetic flux φ in the plane shown in FIG. 1, N of the cavity 7 is considered. Non-uniformity of magnetic flux density occurs at the pole or the S pole. Cabin 7
In order to make the magnetic flux density uniform in the N and S poles of the magnetic field and make the orientation of the magnetic powder uniform, in the case of FIG. 1, the magnetic flux φ entering the inner mold 4 from the first magnetic member 3 of the outer mold Since the amount is large, it is desirable to allow the magnetic flux φ to escape on the upper and lower surfaces of the inner mold 4.

Therefore, it is desirable to design the upper and lower ends of the inner mold 4 so as to project from the upper bottom surface 8 and the lower bottom surface 9 of the cavity 7. The length of the inner mold 4 and the vertical mold inside via the inner mold 4 By changing the magnetic resistance of any
Even with the circumference ratio of the second magnetic members 3 and 5, the magnetic flux density at each pole of the cavity 7 can be made equal.

In this way, the cylindrical magnet having different areas of the N pole and the S pole,
It is often used as a solution to dead center in single-phase motors. 2 and 3 show another embodiment of the present invention. In this embodiment, the ratio of the number of poles to the circumferential length of the first and second magnetic members 3 and 5 in the cavity 7 is odd: even. That is, the boundary of N-S when magnetized in advance to multiple poles (6 poles in FIG. 2, 10 poles in FIG. 3) is the irregular 4-pole NS of this invention. The circumferential lengths of the first and second magnetic members 3 and 5 are determined so as to coincide with the boundaries. Even when magnetized with 6 poles or 10 poles, the NS boundary is not magnetized so strongly. It becomes possible to manufacture magnets.

〔The invention's effect〕

As described above, the present invention uses the molding device in which the peripheral lengths of the cavities of the first and second magnetic members are made different from each other. Therefore, any multipole having no axial length limitation is used. It is possible to manufacture the ring-shaped magnetic molded body of, and its industrial significance is extremely large.

[Brief description of drawings]

FIG. 1 is a schematic plan view of an essential part of a molding device for a ring-shaped magnetic molded body for explaining an embodiment of the present invention, FIG. 2, and FIG.
Similarly, the figure is a schematic plan view of a main part of a molding device for a ring-shaped magnetic molded body for explaining another embodiment of the present invention,
FIG. 4 is a horizontal sectional view showing an example of the molding apparatus used in the present invention, FIG. 5 is a sectional view taken along the line II-II of FIG. 4, and FIG. 6 is another example of the molding apparatus used in the present invention. The horizontal sectional view shown in FIGS. 7A and 7B is taken along line III-III in FIG.
A sectional view taken along line IV-IV, FIG. 8 is a horizontal sectional view showing still another example of the molding apparatus used in the present invention, FIG. 9 is a sectional view taken along line VI-VI in FIG. 8, and FIG. Is VII-VII in FIG.
A sectional view taken along the line, FIG. 11 is a plan view of the experimental apparatus, and FIG.
The drawing is a sectional view taken along the line VIII-VIII in FIG. In the figure, 1 is a pole piece, 2 is a solenoid coil, 3 is a first magnetic member, 4 is an inner die, 5 is a second magnetic member, 6 is a non-magnetic member, 7 is a cavity, 8 is an upper bottom, 9 Is the bottom.

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Claims (4)

[Claims] 1. A molding apparatus comprising a mold including an outer mold and an inner mold, and a solenoid coil provided separately from the mold so as to generate a magnetic field in the mold.
The mold has a ring-shaped cavity formed by a hole provided in the outer mold and the inner mold which is inserted in the hole and is made of a material having a large relative magnetic permeability. ) The outer wall of the cavity has a plurality of first magnetic members having a large relative magnetic permeability, and the same number of the first magnetic members as the first magnetic members having a large relative magnetic permeability in the outer peripheral portion of the cavity. The second magnetic member is interposed between the first magnetic member and the second magnetic member, and the first magnetic member and the second magnetic member are substantially magnetically shielded from each other. Ii) Each of the first magnetic members is magnetically connected to the solenoid coil, and the cavity of the molding apparatus has a magnetic powder containing magnetic powder. The composition is filled in a state in which the magnetic powder can be displaced, and the assembly for the outer mold and magnet The object and the inner mold are magnetically coupled, and a current is passed through the solenoid coil to generate a magnetic field in the same direction with respect to the inner mold in each of the first magnetic members, and the magnetic field is applied to the first magnetic member in the cavity portion. Directing from the magnetic member through the inner mold to the second magnetic member or in the opposite direction to cause the magnetic powder in the cavity to have a radial orientation at each pole, and then to solidify the magnet composition. A method for producing a ring-shaped magnetic molded body, comprising: 2. The ring-shaped magnetic molding according to claim 1, wherein the ratio of the number of poles to the circumferential length of the first and second magnetic members in the cavity portion is odd: even. Body manufacturing method. 3. The axial length of the inner die is determined according to the ratio of the circumferential lengths of the first and second magnetic members in the cavity portion.
The ring-shaped magnetic according to claim (1) or (2), characterized in that it is made longer than the length of the ring-shaped magnetic molded body so that the magnetic flux in the vertical direction of the inner mold increases. Method for manufacturing molded body. 4. The method for producing a ring-shaped magnetic molded body according to claim 1, wherein the mold has a plurality of cavities.