JPH0637641B2 - Method for manufacturing surface multipolar anisotropic permanent magnet body - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a permanent magnet body to be surface-magnetized.

(Background Art) A conventional permanent magnet body is molded by a molding die as shown in FIG. In the figure, 1 is a magnetizing coil,
Reference numeral 2 is a die, and 3 and 4 are upper punches and lower punches, which are fitted into the die 2 so as to face each other. If the ferromagnetic powder material 5 is filled in the die 2 and pressed by the upper punch 3 and the lower punch 4 from above and below, an isotropic molded body is obtained and the magnetizing coil 1 is energized. If pressure is applied while this is being performed, an anisotropic molded body can be obtained. The permanent magnet body obtained by firing this molded body at a predetermined temperature can be magnetized in any direction when it is isotropic, but the magnetic flux density on the magnet surface is low. In the case of anisotropy, only anisotropy in a single direction is added. However, in recent years, permanent magnets have various uses, and demand for magnets having anisotropy in a plurality of directions or magnets having a plurality of poles on the surface is rapidly increasing.

(Object of the Invention) The present invention provides a method for producing a surface multipolar anisotropic permanent magnet body which imparts anisotropy at the time of molding in the same direction as the magnetization direction when a permanent magnet is used. .

Hereinafter, the present invention will be described in detail based on embodiments with reference to the drawings.

(Structure and Operation of the Invention) FIGS. 2 (a) and 2 (b) are a plan view and an AA ′ vertical sectional view of a manufacturing apparatus for carrying out the manufacturing method of the present invention, and the same portions are the same as those in FIG. The same reference numerals are used. In the figure, the dice 2 is made of a ferromagnetic material and has grooves corresponding to the number of poles. The magnetizing coil 6 is embedded in this groove and is shrink-fitted to the die 2 with the non-magnetic material 7, adhered with an adhesive or the like, or fixed by another method. The die 2 is configured as described above, and the space formed by the upper punch 3, the lower punch 4 and the core 8 is filled with the ferromagnetic powder material 5, and the upper punch 3 and the lower punch 4 are filled.
A large current is applied to the magnetizing coil 6 from an external power source while the pressure is moved into the die 2. At this time, a magnetic flux 9 as shown in FIG. 2 (a) is generated directly from the ferromagnetic material of the die 2 in the space, and the ferromagnetic powder material is molded with multipole anisotropy added to the outer peripheral surface. . After the pressurization is completed, an appropriate current in the opposite direction is applied to the magnetizing coil 6 to demagnetize it, and then the molded body is taken out of the mold and fired at a predetermined temperature, in the same direction as the direction in which the anisotropy is added. When magnetized, a high-performance anisotropic permanent magnet body having multiple poles on the surface can be obtained.

FIG. 3 shows the results of comparison of the magnetic characteristics between the isotropic permanent magnet body and the permanent magnet body manufactured according to the present invention by the magnetic flux density on the magnet surface. Since the magnetic flux 9 generated by the magnetizing coil 6 passes through the ferromagnetic material of the die 2 and directly magnetizes the ferromagnetic powder material 5 without the interposition of a non-magnetic material,
A high-performance surface multipolar anisotropic permanent magnet body with a ratio of 1.6 times that of an isotropic magnet can be obtained.

The above is an example in the case of manufacturing a cylindrical surface multi-pole anisotropic permanent magnet body, but the cross-sectional shape of the molded body is not limited to the above-mentioned cylindrical shape, but a circular shape, a rectangular shape, a half-moon shape or other geometric shapes. The same applies to the case of the target shape. Further, the anisotropy is not limited to the surface of the die 2, but as shown in FIGS. 4 and 5, the anisotropy is applied from any one of the surfaces of the upper punch 3, the lower punch 4 and the core 8 or from a plurality of directions. Can also be attached. Furthermore,
Ferromagnetic material powders to which the present invention is applicable include hard ferrite magnet powders and rare earth magnet powders, and not only dry powders but also slur-like materials containing a liquid such as water or kneading with a resin or the like.

(Effects of the Invention) As described above, according to the present invention, at the time of molding a surface multipole anisotropic permanent magnet body, an upper punch, a lower punch, or The non-magnetic surface provided on the die die is brought into contact with the ferromagnetic powder material to prevent a magnetic short circuit, and the portion to which surface multipolar anisotropy is applied is provided on the upper punch, the lower punch, or the die die. In addition, since the ferromagnetic surface is magnetized by directly contacting the ferromagnetic powder material, it is possible to manufacture a permanent magnet body having a small magnetic loss and an extremely high surface magnetic flux density. In particular, according to the present invention, it is possible to manufacture a permanent magnet body having a higher surface magnetic flux density than in the case of using a mold in which the entire circumference of the space filled with the ferromagnetic powder is made of a non-magnetic material. It is possible.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a conventional powder permanent magnet molding apparatus, FIGS. 2 (a) and 2 (b) are plan views and vertical sectional views showing an embodiment of the present invention, and FIG. 3 is a conventional view. FIG. 4 is a longitudinal sectional view showing another embodiment of the present invention, and FIG. 4 and FIG. 5 are characteristic comparison diagrams of the permanent magnet body manufactured by the manufacturing method of the present invention and the surface multipolar anisotropic permanent magnet body manufactured by the manufacturing method of the present invention. It is a top view. 1, 6: magnetizing coil, 2: die, 3: upper punch, 4: lower punch, 5: ferromagnetic powder material and molded body, 7: non-magnetic body, 8: core, 9: magnetic flux.

Claims (1)

[Claims] 1. At least one of an upper punch, a lower punch, and a die die is made of a ferromagnetic material, and an upper punch, a lower punch, or a die die made of a ferromagnetic material is an upper die. There is a groove in contact with the space surrounded by the punch, the lower punch, and the die die, and the magnetizing coil is embedded in the groove, and at least the space side of the magnetizing coil has a non-magnetic surface in contact with the space. The upper punch formed with a ferromagnetic material, the lower punch, or the die surface of the die, except for the non-magnetic surface, is formed with a ferromagnetic surface.
The space is filled with ferromagnetic powder, and the inner volume of the space is adjusted to the upper punch and the lower volume while energizing the magnetizing coil with the ferromagnetic powder and the non-magnetic surface in contact with the ferromagnetic powder. A method for producing a surface multipolar anisotropic permanent magnet, which comprises pressurizing and compressing with a punch to reduce the ferromagnetic powder, and molding the ferromagnetic powder.