JPH0624174B2 - Manufacturing method of cylindrical magnet - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a cylindrical magnet magnetized in a radial direction with multiple poles, in particular, a resin composition molded magnet containing magnetic powder.

[Conventional technology]

Cylindrical magnets with multiple poles in the radial direction are widely used for various applications including small motors. In order to manufacture a high-performance cylindrical magnet with multiple poles in the radial direction, in the process of molding the magnetic powder into a cylindrical shape, the magnetic powder is oriented in the radial direction to form a cylindrical magnetic molding having magnetic anisotropy. It is desirable to use the body. 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 cylindrical molded body in which the orientation of such magnetic powder is aligned in the radial direction.

[Problems to be solved by the invention]

Generally, the method for manufacturing a multi-pole radial cylindrical magnet is to orient the magnetism in the radial direction, demagnetize it once, and then magnetize it to a desired number of poles to form a cylindrical 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 cylindrical magnetic molded body and then drawn out during orientation is determined by the inner diameter cross-sectional area of the cylindrical magnetic molded body and cannot be increased. Although it depends on the magnitude of the orientation magnetic field in the radial direction, the length of the cylindrical magnetic molded body is generally limited to about 50% of the inner diameter, and if the length is longer than this, the orientation in the radial direction is good. Performance is reduced because it is not protected. When designing a multi-pole motor that is long in the axial direction, a plurality of cylindrical magnets are stacked in the axial direction, or long C-shaped segment magnets are attached to each other. Also, when it was absolutely necessary to use a magnet with a cylindrical integral body, a magnet with a low orientation performance was inevitably used. Japanese Patent Application No. 59-4226
No. 9 discloses a method for manufacturing a radial multipole cylindrical magnet by a method in which such a restriction on the cylindrical length does not substantially exist.

This method is an extremely epoch-making method in which a large number of cylindrical magnets can be manufactured using one die, but there is a problem that the die structure becomes complicated when the number of poles is increased. The structure of the mold is relatively simple, and the number of poles that makes it easy to pick many is 4
Or 6

The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for manufacturing a cylindrical magnet that is magnetized into multiple poles.

[Means for solving problems]

In the method for manufacturing a cylindrical magnet according to the present invention, first, a die including an inner die and an outer die is formed, and an inner die formed of a hole provided in the outer die and a material having a large relative magnetic permeability inserted in the hole. A ring-shaped cavity is formed with the mold, and an outer wall of the ring-shaped cavity is formed with a plurality of first magnetic members having a large relative permeability and the same number of second magnetic members having a large relative permeability. A magnetic powder is applied to the ring-shaped cavity by using a molding device which is alternately arranged and is annularly arranged so as to be substantially magnetically shielded, and in which the first magnetic member is magnetically connected to the solenoid coil. The magnetic composition in which the magnetic powder is filled in such a manner that the magnetic powder can be displaced, the outer mold, the magnetic composition and the inner mold are magnetically coupled to each other, and a current is passed through the solenoid coil to form the magnetic powder in the ring-shaped cavity. Cause a polar orientation, then Build a cylindrical magnetic shaped bodies solidifying the stone composition, then subjected to demagnetization, and then the boundary of m poles when aligned to match the boundary of magnetization of m · n / 2-pole and m · n /
Two-pole magnetization is performed.

[Action]

In the present invention, first, a pole-oriented cylindrical magnetic molded body with m poles is produced, then demagnetized, and then the boundary of the m · n / 2 poles is aligned with the boundary of the m poles during orientation.・ N / 2
Since the poles are magnetized, it is possible to obtain a multi-pole cylindrical magnet having an unlimited length.

〔Example〕

Since the present invention utilizes the previously proposed method for producing a ring-shaped magnetic molded body of Japanese Patent Application No. 59-42269, the above-mentioned previously-proposed invention will be described before describing the embodiments of the present invention.

FIG. 9 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 apparatus used in the method for manufacturing the ring-shaped magnetic molded body proposed above. FIG. 10 shows a relationship, and is a cross section perpendicular to the central axis of the cavity of the molding apparatus, that is, I- in FIG.
It corresponds to a sectional view taken along line I. Fig. 10 is II- in Fig. 9.
It corresponds to the cross-sectional view along the line II. In the figure, 1 is a pole piece, 2 is a solenoid coil surrounding the pole piece, 3 is a first magnetic member which is in magnetic contact with the pole piece 1 at its end, and 4 is an inner mold, 5 is the second magnetic member,
6 is a non-magnetic member, and 7 is a ring-shaped cavity.
(Because the invention proposed above is characterized by the magnetic mutual relation of each part of the molding apparatus used, means for supplying the composition for magnet to the cavity 7 and means for taking out the molded body from the cavity 7 etc. Since the mechanical structure of the molding apparatus of (1) 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. First
The magnetic members 3 and the second magnetic members 5 are alternately arranged in an annular shape around the cavities 7 so as to form an outer wall of the cavities 7. The non-magnetic member 6 is provided to cut off the magnetic coupling between the magnetic elements 3 and 5.
Is intervening. In FIG. 9, the first magnetic member 3
And the second magnetic member 5 do not come into physical contact with each other,
Although a part of the outer wall of the cavity 7 is composed of the non-magnetic member 6, 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. In this way, the outer wall of the cavity 7 can be composed of only the first and second magnetic members 3 and 5. First and second
Even if the magnetic members 3 and 5 of 1 are in contact with each other at their ends, this portion is magnetically saturated immediately, so the magnetic flux passing therethrough is small and can be almost ignored.

In order to manufacture a polar-oriented ring-shaped magnetic compact using the apparatus shown in FIG. 9, first, the cavity 7 is filled with the 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 shown in FIG. 9, the second magnetic member 5 is made longer 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 a diameter 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. 10, the first magnetic member 3
The upper and lower ends of the second magnetic member 5 are formed obliquely toward the cavity 7 (although not shown in the figure, the end of the second magnetic member 5 has 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. 10, 8 is the upper bottom of the cavity 7 and 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. To be done.

Although FIG. 9 and FIG. 10 show an apparatus for producing a 4-pole molded body, it is also possible to produce a multi-pole molded body. For example, FIG. 11 shows a solenoid coil 2 which is an example of an apparatus for producing a 6-pole molded product, a first magnetic member 3, a second magnetic member 5 and a non-magnetic member 6 which form an outer mold, and an inner mold 4. FIG. 9 is a diagram conceptually showing the arrangement relationship of No. 4 and corresponds to FIG. 9 in the case of four poles. In addition, in FIG. 11, the second
As shown in FIG. 12 (a), the magnetic member 5 of FIG. 12 extends in the up-down direction of the cavity 7 and is configured so that the leakage of the magnetic field from the end thereof does not affect the magnetic field of the cavity 7. 12 (a) and 12 (b) are shown in FIG.
It is sectional drawing by the III-III line and the IV-IV line.

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. Similar to FIGS. 9 and 11, FIG. 13 shows an example solenoid coil 2 in the case of using a mold having a plurality of such cavities 7, a first magnetic member 3 constituting the outer mold, 2 shows the positional relationship between the magnetic member 5 and the non-magnetic member 6 and the inner mold 4 of FIG. 2, and corresponds to a sectional view taken along the line VV of FIG. It should be noted that FIGS. 14 and 15 are respectively shown in FIG.
It corresponds to a cross-sectional view taken along lines VI-VI and VII-VII in the figure. 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. In addition, the first magnetic member 3 of each cavity 7 is a pole piece 1 separately.
Although it is connected to the pole piece 1, it may be connected to the pole piece 1 collectively. Further, in this case, the second magnetic member 5 also has a cavity 7 as shown in FIG.
Extending in the vertical direction. Generally, the upper and lower bases 8 and 9 of the cavity 7 are vertically projected at least twice the diameter of the cavity 7, preferably 2 to 5 times. FIGS. 14 and 15 show that the first magnetic member 3 and the second magnetic member 5 are formed such that the ends thereof 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, there are arranged backing materials 11 and 12 made of a non-magnetic material, respectively, so as to keep the mechanical strength of the mold. In addition, in FIG. 14 and FIG. 15, the second magnetic member 5 is
These are magnetically coupled to each other by a magnetic member 10 that freezes them, and reduces the influence of leakage of magnetic flux on the cavity 7.

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 and the pole piece 1 was at a position about 1/4 from the end (see FIGS. 16 and 17). 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. 16 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 The cylindrical magnetic compact thus constructed was demagnetized and then used for ordinary cylindrical multipole magnetization shown in FIG. Magnetization is performed using the pulse magnetizer 21.

In FIG. 1, 22 is an external magnetic path portion, 23 is a pole piece, and 24
Is a coil, 25 is an internal magnetic path portion, 20 is a cylindrical magnetic molded body, and φ is a magnetic flux. In this case, it should be noted that the boundary of the m pole at the time of orientation and the boundary of the m · n / 2 pole to be magnetized are made to coincide with each other. This point will be described below.

The cylindrical magnetic compact manufactured by the previously proposed invention described above has an orientation as shown in FIG. When the orientation of the magnetic powder (indicated by the arrow) of the cylindrical magnetic compact 20 oriented in four poles is examined in detail, the central portion of the pole is oriented almost completely in the radial direction, and in the vicinity of the boundary of the N-S pole, the radial direction. I found that it was out of alignment. If the disturbed region deviated from the radial direction is represented by an angle α from the center, this α changes depending on the ratio of the outer diameter D _O and the inner diameter D _I of the cylindrical magnet, and D _I / D _O > 0.9. In the case, that is, in the case of the thin cylindrical magnetic molded body 20, normally, α <5 to 10 °, and it is limited to a very narrow region. Therefore, in the case of the thin cylindrical magnetic molded body 20, most of them are oriented in the radial direction.

When the pulse magnetizer 21 of FIG. 1 is used near the NS boundary, the radial magnetizing magnetic field in the vicinity of NS is not so large and is not magnetized so much. Therefore, after temporarily demagnetizing the thin cylindrical magnetic molded body 20 oriented in four poles,
Using a magnetizer (for 8 poles) as shown in the figure and magnetizing it with the boundary between the orientation and the poles of magnetization aligned, the cylindrical magnet with a completely radial orientation as shown in FIG. Almost the same magnetization pattern as that of the 8-pole magnetization can be obtained.

When the cylindrical magnetic molded body 20 becomes thicker, the angle α of the region which is deviated from the radial direction and is disordered and oriented increases, but in this case, the portion where the pulse magnetizer 21 contacts the boundary of each pole. In addition, by providing the concave portion 20A as shown in FIG. 3, it is possible to substantially eliminate the influence of the difference in the orientation of the magnetic particles at the NS boundary. As shown in FIG. 3, the molding of such a cylindrical magnet is performed by using the cavity 7 (9th embodiment) of the molding die so that the N-S boundary corresponding to the number of poles of the magnetizer is thinned.
Figure) should be formed.

Even if the magnet has a perfect cylindrical shape, as shown in FIG. 4, the orientation is adjusted so that the radial orientation of the portion corresponding to the NS boundary corresponding to the number of poles of the pulse magnetizer 21 is weakened. The structure of the ferromagnetic material of the cavity 7 of the mold may be arranged. Needless to say, if the N-S boundary is weakened in magnetizing or no magnetizing portion is provided, each pole can be used as an equivalent pole in the rotating machine.

Next, still another embodiment of the present invention will be described. FIG. 9 described above discloses a mold structure in which the first magnetic member 3 and the second magnetic member 5 have the same peripheral length at the outer peripheral portion of the cavity 7. In this case, The upper and lower ends of the mold 4 are usually aligned with the upper and lower surfaces 8 and 9 of the cavity 7. However, in the present invention, for example, considering the balance of the magnetic flux in the plane shown in FIG. 6, since the circumferences of the first and second magnetic members 3 and 5 at the cavities 7 are different, the N pole of the cavities 7 or Non-uniformity of magnetic flux density occurs at the S pole. In order to make the magnetic flux densities uniform in the north and south poles of the cavity 7 and evenly orient the magnetic powder, in the case of FIG. 6, the magnetic flux entering the inner mold 4 from the first magnetic member 3 in the outer mold. Therefore, it is desirable that the magnetic flux is released 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. 7 and 8 show another embodiment of the present invention. That is, N-S in the case of previously magnetizing to multiple poles (6 poles in FIG. 7 and 10 poles in FIG. 8)
The perimeters of the first and second magnetic members 3 and 5 are determined so that the boundary of (1) coincides with the irregular 4-pole NS boundary of the present invention. Even when magnetized with 6 or 10 poles, the NS boundary is not magnetized so strongly.
It is possible to manufacture an arbitrary multi-pole cylindrical magnet from the irregular 4-pole oriented cylindrical magnet of the present invention.

〔The invention's effect〕

As described above, according to the present invention, an m-pole magnetically oriented magnetic body is produced, then demagnetized, and then the boundary between the m-pole and the n / 2-pole is aligned with the boundary of the m-pole during orientation. Let me m
Since the n / 2 poles are magnetized, it is possible to manufacture an arbitrary multipole cylindrical magnet without any limitation in the axial length, and its industrial significance is extremely large.

[Brief description of drawings]

FIG. 1 is a schematic plan view of a pulse magnetizer for magnetizing a cylindrical multipole for explaining one embodiment of the present invention, and FIG. 2 is a diagram showing a magnetized state by the pulse magnetizer shown in FIG. FIG. 3 and FIG. 4 are schematic plan views of a main part of a molding device for a cylindrical magnetic pole molded body for explaining another embodiment of the present invention, and FIG. 5 explains the orientation of the magnetic poles of the cylindrical magnetic molded body. FIG. 6, FIG. 7, FIG. 8 and FIG. 8 are schematic plan views of the essential parts of a molding apparatus for explaining still another embodiment of the present invention, and FIG. A horizontal sectional view showing an example of a molding apparatus used in the present invention, FIG. 10 is a sectional view taken along line II-II of FIG. 9,
FIG. 11 is a horizontal sectional view showing another example of the molding apparatus used in the present invention, and FIGS. 12 (a) and 12 (b) are III-I in FIG.
Sectional views taken along line II and IV-IV, FIG. 13 is a horizontal sectional view showing still another example of the molding apparatus used in the present invention, and FIG. 14 is a sectional view taken along line VI-VI of FIG. 15 is a sectional view taken along the line VII-VII of FIG. 13, FIG. 16 is a plan view of the experimental apparatus, and FIG. 17 is a sectional view taken along the line VIII-VIII of 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 2
Reference numeral 0 is a cylindrical magnetic molded body, 21 is a pulse magnetizer, 22 is an external magnetic path portion, 23 is a pole piece, 24 is a coil, and 25 is an internal magnetic path portion.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location B29K 105: 18 B29L 31:34

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 second magnetic members having the same large relative magnetic permeability between the first magnetic members. The second magnetic member is interposed, and the first magnetic member and the second magnetic member are annularly arranged so as to be substantially magnetically shielded from each other. Ii) The above Each of the first magnetic members is magnetically connected to the solenoid coil, and the cavity of the molding apparatus is filled with a magnet composition containing magnetic powder in a state in which the magnetic powder can be displaced to form an outer mold. , Magnetically coupling the composition for magnets and the inner mold, A magnetic field is generated in each of the first magnetic members in the same direction with respect to the inner mold, and a magnetic field is generated from the first magnetic member through the inner mold to the second magnetic member in the cavity portion. Or by orienting in the opposite direction, the magnetic powder in the cavity is caused to have an m-pole orientation, then the composition for a magnet is solidified and then demagnetized, and then the boundary of the m-pole at the time of the orientation is applied. A method for producing a cylindrical magnet, characterized in that multi-pole magnetization of m · n / 2 poles is performed by matching the boundaries of the magnetic poles of m · n / 2 poles. However, m is an even number, and n is N, S in the orientation of the m pole.
If the areas of the poles are equal, the number is even, and if they are not equal, the number is odd. Also, select m and n so that m · n / 2 is an even number. 2. The cylindrical magnet according to claim 1, wherein the cylindrical magnet is provided with a magnetic concave portion on a circumference of a portion corresponding to each boundary of m · n / 2 poles. Method. 3. The method for producing a cylindrical magnet according to claim 1, wherein the cylindrical magnet is provided with a magnetic recess on the outer periphery of a portion corresponding to the boundary between the m and n / 2 poles. 4. The cylindrical magnet according to claim 1, wherein the radial orientation of the magnetic powder in the portion that becomes the boundary between the m and n / 2 poles is weaker than that in the other portions. Manufacturing method.