JPS58181802A - Manufacture of ring-shaped permanent magnet anisotropic along its radial direction - Google Patents

Abstract

PURPOSE:To simplify the structure of dies, while improving work efficiency, by providing a couple of field coils oppositely to each other at right and left about the dies, and performing compression-forming while repulsing magnetic fluxes by the impression of magnetic fields having the same polarity. CONSTITUTION:A couple of field coils 3, 3' are provided at both of the right and left sides of a ring-shaped cavity defined by a die 1, a core rod 6 and a lower die 5, in a manner such that they are arranged in vertical postures at positions symmetric about an axial line along the vertical center of the ring. Said ring-shaped cavity is filled with magnetic powder, and compression-forming is performed by an upper die 4. Magnetic fluxes are formed along the arrow 8 by coupled field coils 3, 3' and let horizontally permeate from both of the right and left ends into the ring of the magnetic powder, so that the rectangular cross of a line of magnetic induction to the wall of the ring can be assured. Since the interior of the upper die 4 is hollow, the magnetic fluxes from the right and left sides repulse to each other at the central part of the ring and then permeate downwards through the core rod 6. Thus, the ring-shaped compressed powdery body of good quality anisotropic along its radial direction is formed.

Description

Detailed Description of the Invention The present invention relates to a method for manufacturing a radially anisotropic ring permanent magnet, and particularly to a method for manufacturing a radially anisotropic ring permanent magnet by pressure forming in a magnetic field. The present invention relates to the above-mentioned manufacturing method, characterized in that magnetic field coils are placed opposite to each other on the left and right sides with a powder molding die in between, and pressure molding is performed while repelling magnetic flux by applying a homopolar magnetic field.

BACKGROUND ART Ring permanent magnets used in various motors including stepping motors have conventionally been manufactured by a pressure molding method in a magnetic field. In the magnetic field pressure molding method, a powder molding die is filled with magnetic powder, and the magnetic powder is pressure molded into a lander shape by the cooperative action of an upper weir and a lower mold, and at the same time, a radial magnetic flux is generated through a ring using a magnetic field coil. In this way, a compressed ring magnetized in the radial direction of the ring wall is obtained, and then a desired ring permanent magnet is produced through a sintering operation.

Referring to the drawings, FIGS. 1 and 2 show a conventionally practiced basic method in which a ring-shaped cavity formed by a die 1 and a center rod 6 is filled with magnetic powder 7 such as ferrite. . It is supported on the lower side within the ia magnetic powder cavity by a lower mold 5 which is inserted into the ring cavity in an eave-wise manner.

An upper mold 4 is arranged above the die 1 in alignment with the cavity. A magnetic field coil S is shown in FIG. 1 at the bottom of die 1 and at the second
1, it is installed above the magnetic flux l1 as shown by the arrow.
1B respectively. During pressure forming by the upper mold 4, the magnetic flux lines pass through the ring wall in a substantially radial direction. However, with this manufacturing method, in any case, the magnetic field strength decreases as the distance from the magnetic field coil 5 increases, so an imbalance in magnetic properties inevitably occurs in the ring height direction.

Therefore, in order to solve the problem of unbalanced magnetic properties in the ring height direction, the next manufacturing method adopted was to install magnetic field coils 3 and 5' above and below the die 1, as shown in Figure 3. , by applying a homopolar magnetic field to both magnetic field coils 3 and 51, while repelling the magnetic flux from above and the magnetic flux from below, pressure is applied to 1 under the pattern of magnetic flux lines 8 as shown by the arrows in Fig. 5. It was a method of molding. However, in this manufacturing method, the upper magnetic field coil h5 and the lower magnetic field fill 5'' surround the upper W4 and the lower mold 5, respectively, and are installed above and below the die 1, which severely restricts the work space. Hey, die 1
Since the magnetic field coil 5' is installed at the bottom of the die, the die structure is complicated and the mold cost is increased. Furthermore,
When molding several pieces at the same time, it is necessary to install magnetic field coils around the upper and lower molds, which limits the number of molds to be taken, and it is not possible to expect a significant improvement in productivity. More importantly, the magnetic flux lines that repel each other from above and below and are deflected horizontally through the magnetic powder ring wall do not necessarily pass completely radially through the ring wall, resulting in the desired radial anisotropy. Sometimes I can't. Due to equipment constraints, it may not be possible for the repelling surfaces of the upper and lower magnetic fluxes to be at the center of the magnetic powder ring, and unbalance in the ring height direction may still occur. There was also the fear of having to remove the magnetic field coil each time the mold was replaced.

In view of the above-mentioned drawbacks of the prior art, the present invention aims to minimize the interference between the magnetic field coil and molding parts such as the upper die, the lower die, and the die while generating a more complete radial magnetic flux. It is an object of the present invention to provide a method for manufacturing high quality radially anisotropic ring permanent magnets that allows for more efficient work and allows for the construction of mold structures.

In the present invention, a pair of magnetic field coils are placed opposite each other on the left and right sides with a die in between, and pressure molding is performed while repelling magnetic flux by applying a homopolar magnetic field. By doing this, the magnetic field coil pair can be installed away from the molding section consisting of the die, upper mold, lower mold, etc., which simplifies the mold structure and allows for a wide frontage, making it extremely efficient. Pressure work can be carried out. Since the magnetic flux is generated perpendicular to the pressing direction, that is, perpendicular to the wall of the magnetic powder ring during molding, a product with extremely uniform magnetic properties can be manufactured.

This will be explained based on the specific example shown in FIG. The reference check is the same as in cases 1 to 512'. According to the invention, a pair of magnetic field coils 3 and 5' are arranged in a vertical position in a symmetrical device with respect to the vertical center axis of the ring on both left and right sides of the ring-shaped cavity defined by the die 1, the middle rod 6 and the lower die 5. It will be installed in In this way, a magnetic flux as shown by the arrow 8 is generated by the tapping coil pair 5 and sl, and is applied horizontally from both left and right sides to the magnetic powder ring that is filled in the ring-shaped cavity and is being pressurized by the upper #14. to penetrate. Unlike the prior art case shown in FIG. 3, orthogonality between the magnetic flux lines and the ring wall is guaranteed. Since the inside of the upper mold 4 is hollow,
The magnetic flux from the left and right sides repel each other at the center of the ring.
passes downward. Finally, a radially anisotropic ring pressurized T48 body of crow quality is produced.

Mechanical interference between the magnetic field coils and the molding part is eliminated by placing the magnetic field coil pairs 3 and 5' on both left and right sides of the molding part consisting of the die 1, upper mold 4, lower mold 5, and middle mold 986. This not only simplifies the mold structure, but also allows for a wider working space, making it easier to work and making it possible to perform surface-pressure forming cedar work efficiently. When replacing molds, work can be done with the magnetic field coil still in place, which reduces work time and greatly contributes to improving operating rates. Furthermore, since the opening is wide, it is easier to mold several magnetic powder rings at the same time.

Further, as shown in FIG. 5, by arranging a ferromagnetic member 2 made of iron or the like in the hollow part of the upper mold 4, the magnetic path is divided into two in the vertical direction, and the magnetic resistance is halved. Therefore, the magnetic field strength in the magnetic powder molded portion is increased approximately twice, and the uniformity of the magnetic field strength increases along the ring height, making it possible to obtain a molded product with high characteristics.

Furthermore, when molding multiple rings at the same time,
Because the magnetic resistance of each mold is uneven, and because the placement of each molding part is different, the magnetic field strength of each powder molding part is different. As a result, the magnetic properties (B occurs.

In order to avoid this inconvenience, the magnetic field strength in the powder molding part of the mold can be made uniform by adjusting the cross-sectional area of the ferromagnetic material 2 held in the hollow part of each upper mold 4 or by changing the thickness of the material. is measured. In this way, it becomes possible to simultaneously produce a large number of magnetic powder cylinders with stable characteristics.

Examples are shown below.

Example 1 A seven-piece light radially anisotropic ring permanent magnet having the dimensions shown in the table below was manufactured using the apparatus shown in FIG. The magnetic field coil is 5o from the die center axis.

It was installed symmetrically on the side of the street. The operating conditions of the device were as follows.

Upper mold pressurized crab 2 o mouth ~ SO oky/cm" Maximum magnetomotive force of 2 coils 4 (LOOO m/piece magnetic field) Strength: Varies depending on mold dimensions (distributed in the following table for consideration) Obtained The magnetic properties of 12 rings are shown below.

Each ring was uniformly anisotropic in the ring height direction and was of high quality.

Example 2 Using the same device as shown in Fig. 4 without inserting any iron material into the hollow part of the upper mold of the 9th position of Example 1, a 661 m outer diameter x5 & inner diameter x
A cylinder with a height of 401 Im was manufactured. Comparison data between the case with and without inserting iron material is shown below.

By inserting the iron material, the magnetic field strength could be more than doubled, resulting in a ring with high properties.

Example S 4 rings having dimensions of 2 & Hatakewara no Miki outer diameter x 21 mm, inner diameter x I 511 m + height were molded at the same time. Due to the difference in magnetic resistance of the die, the iron material inserted into the hollow part of the upper mold is
When the CI+" cross section was the same, the magnetic field strength and generation ring lr varied considerably as shown in the table below. However, by adjusting the cross sections of the iron materials inserted into the four upper molds, the variation in characteristics could be reduced. A extraction effect was obtained.The results are shown in the table below.

As explained above, the present invention is a permanent radial anisotropic ring in which a pair of magnetic field coils are placed opposite to each other on the left and right with a die sandwiched between them, and a homopolar magnetic field is applied to repel the bundle while applying pressure. This is a method for manufacturing magnets, and is extremely unique in that it enables the production of high-quality products with improved work efficiency compared to conventional methods.

[Brief explanation of drawings]

1st. Figures @2 and S are schematic #r side views of a magnetic field pressure forming apparatus according to the prior art, and Figures 4 and 5 are schematic sectional views of a magnetic field pressure forming apparatus according to the present invention. 1: Die (ferromagnetic material) 5.5': Magnetic field coil 4! Upper mold (non-magnetic material) 5z Lower 3M (non-magnetic material) 6: Middle bar (-magnetic material, however @ non-magnetic material in Figure 2)
7: Magnetic powder 8: Lines of magnetic flux 2: Ferromagnetic material such as iron material, Δ (-21 410 Figures 2 and 5 Procedural Amendments December 14, 1980 Patent Office Nagatomi S. Kazuo Sugi Case Display 1982 Year Special Sales No. 64045 Name of the invention Relationship with the case of a person amending the manufacturing method of backward anisotropic ring permanent stone Patent applicant name (SΩ6) Tokyo Denki Kagaku Kogyo Co., Ltd. Agent 103 Address Tokyo 3-13-11 Nihonbashi, Chuo-ku, Oils and Fats Industry Hall, Telephone: 273-6436 Address: Supplementary Edition USupplement I [Invention in the applicant's column specification of the subject application?8 Scope of claims・Contents of Ura Masa in the column of detailed description of the invention As shown in the attached document, the specification of No. 1987-4406S is amended as follows in 411. Range 1) In a method of manufacturing a radially anisotropic ring permanent magnet by forming magnetic powder filled in a die into an upper mold and a lower mold (thus forming a magnetic field medium fine fEit shape), a pair of magnetic field coils are placed in the die. They are sandwiched and placed facing each other on the left and right, and pressure molded while repelling the magnetic flux by applying a homopolar magnetic field.
A method for manufacturing a radially anisotropic ring permanent magnet. 2) The method according to claim 1, wherein a ferromagnetic material is inserted into the hollow part of the upper mold to reduce the magnetic resistance of the magnetic circuit. 3) The die is provided with a plurality of molding parts, and the same number of upper molds and lower molds are provided, a strong ia material is inserted into the hollow part of each upper mold, and the boundary strength of the plurality of molding parts is made uniform. Insert the ferromagnetic material to measure it! ! *@! The method according to claim 1, wherein the material is changed once the rtx is processed. ” On page 7 of 2, the last line “JR Eru” is corrected to “change to equalize the resistance at once.” 5 On page 10, insert the product 1 between the two lines from the bottom between ``Shingeki'' and ``wo''.

Claims (1)

[Claims] 1) A method for manufacturing a radially anisotropic ring permanent magnet by press-molding magnetic powder filled in a die in a magnetic field using an upper mold and a lower mold, in which a pair of magnetic field coils are used. A method for manufacturing a radially anisotropic ring permanent magnet, which is characterized by placing Maeki dies in between and facing each other on the left and right, and press-molding while repelling the huangdong by applying a homopolar magnetic field. 2) The method according to claim 1, wherein the ferromagnetic material side is inserted into the hollow part of the upper mold to reduce the magnetic resistance of the magnetic path. 5) The die is provided with a number of molding parts, and the same number of upper and lower molds are provided, a ferromagnetic material is inserted into the hollow part of each upper mold, and! The method according to claim 1, wherein the dimensions and material of the inserted ferromagnetic body are changed so as to equalize the magnetic field strength of the 1M molded parts.