JPS6169104A - Semicircular anisotropic ferrite magnet and manufacture thereof - Google Patents

Abstract

PURPOSE:To manufacture the semicircular anisotropic ferrite magnet of high residual magnetic flux density with an excellent yield of production by a method wherein the opened leg part side of a molded body is placed on a sintering base plate, and a sintering work is performed while the prescribed load is being applied in the vicinity of the center part of the outer circumferential surface of the molded body. CONSTITUTION:In the sintering of the molded body 1, consisting of molecular formula Mo.nFe2O3 (at least a kind of M; Ba, Sr and Pb, n; 5.5-6.2), of arcuate form having the center angle of theta=155 deg.-175 deg. and having the anisotropy of orientational coefficient of 30% or above radiately in radical direction from the center point, the open leg part side of the molded body 1 is placed on a sintering base plate 3, and a sintering work is performed while the load of 10-200% of the weight of the molded body is being applied. As a result, a semicircular anisotropic ferrite of arcuate form, having the center angle theta=165 deg.-182 deg., consisting of the molded and sintered body of anisotropy of the orientational coefficient of 80 deg. or more radiately in radical direction from the center point and also having the residual magnetic flux density of Br 4,000(G) or above, can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Field This invention is applicable to 1ylo + n Fe2O2 (M:
at least one of Ba, Sr, and Pb; 5.
5 to 6.2) and a method for manufacturing the same.

BACKGROUND ART In general, so-called ring-type anisotropic ferrite magnets used in micro motors, generators, etc. include integrated magnets and split magnets. In the case of an integrated magnet, when sintering a molded body, the shrinkage rate is different in the radial direction, which is the direction of the magnetic field, and in the height direction, which is perpendicular to the magnetic field direction. The higher the magnetic field applied in the radial direction, the greater the difference in shrinkage rate during sintering, which causes cracks and cracks to occur on the inner and outer peripheries of the sintered body, resulting in a reduction in product yield. Therefore, if the applied magnetic field strength during molding is lowered, the magnetic field of the sintered body will be reduced to 1! Conventionally, the residual magnetic flux density of an integrated sintered magnet could only be reduced to a maximum of about 3000 to 3200 (G) due to a decrease in f properties.

In the case of Y/2, 22-split type (eclipse), several bow-shaped ferrite magnets are used, but when sintering the bow-formed body, the inner circumferential surface of the molded body is Due to the difference in the shrinkage rate of
However, cracks or defective cracks may occur on the outer peripheral surface of the sintered body, resulting in a decrease in product yield. ) However, the maximum center angle could only be obtained at C145°. Therefore, it is necessary to combine three or four sintered bodies processed so that the center angle of the bow-shaped sintered body has the required angle, and to integrate them into one, which requires a large amount of processing and assembly steps. [It was difficult to use a ring-shaped magnet with sufficient magnetic properties without C.

Purpose of the invention p L (7) f'? -bright+
1. The purpose is to create a semicircular anisotropic ferrite magnet that is easy to assemble, has a good appearance, and has excellent magnetic properties to form a round-shaped magnet. The purpose of the present invention is to provide a manufacturing method that can manufacture semicircular anisotropic ferrite magnets with excellent magnetic properties without causing VL deviation or turtle cape.

Description and Effects of the Invention The present invention provides a method for controlling the shrinkage characteristics during the sintering reaction of a semicircular molded body, with the aim of producing an anisotropic ferrite magnet with a high residual magnetic flux density and a circular shape. As a result of various studies, when sintering a molded body with specific properties, the open leg side of the molded body is placed on a sintering base plate, and near the center of the outer peripheral surface of the molded body,
It has been discovered that semicircular anisotropic ferrite magnets with high residual magnetic flux density can be manufactured with good yield by sintering while applying a predetermined load.

That is, this invention has the following molecular formula: Mo.n Fe2O2 (M: Ba, Sr
, at least one type of Pb, n; 5.5 to 6.2), has an arcuate shape with a center angle θ = 155° to 115°, and has an orientation rate radial in the radial direction from the center point. In sintering a molded body having an anisotropy of 80% or more, the open leg side of the molded body is placed on a sintering base plate, and 10 of the molded weight is placed near the center of the outer peripheral surface of the molded body. %~200% load (
By sintering while adding =J, the center angle l2 +
It is made of a molded sintered body having an approximately 1' circular shape C1 extending from G5° to 182° to the right and having anisotropy with an orientation rate of 80% or more radially from the center point, with a 1iJU retention bundle density Br40
The gist is to obtain i in semicircular traverse magnets 1 to 1 with magnets having 00 (G) or more.

With this invention, in 11 circuits for generators, DC motors, VCM rivers, etc., the processing and assembly man-hours are reduced δ and k, the total surface magnetic flux number Φ is improved, and the variation in the surface magnetic flux direction distribution is reduced. The reduction effect is achieved, and it is effective in improving the torque characteristics as well as the problem of the motor circuit.

Furthermore, compared to conventional magnets, the present invention's:
r), which helps to make the equipment smaller and lighter. Also, it is possible to produce various arcuate and semicircular sintered bodies from molds of the same shape and size, and the number of molds can be reduced. Effective in reducing

DISCLOSURE OF THE INVENTION This invention has a molecular formula of Mo ・n FFe203(;B
at least one of a, Sr, and Pb, n: 5.5 to 6
．． It can be applied to ferrite magnets consisting of 2).

In the semicircular anisotropic ferrite F41 stone according to this invention, the center angle θ is set to 165° to 182°.
If it is less than 5 degrees, the air gap between the magnets in the assembled magnetic circuit becomes large, leakage magnetic flux occurs between the magnetic circuit and the yoke, and the characteristics deteriorate such that the magnetic flux density becomes uneven. When incorporated into a micro motor, DC motor, etc., the magnetic noise will be louder, which is not desirable, and the 182°
This is because if it exceeds this value, the tensile stress generated on the outer circumferential surface of the molded body and the compressive stress generated on the inner circumferential surface of the molded body during sintering will cause cracks and cracks in the sintered body, making it impossible to obtain a product with a good appearance. In addition, the center angle is determined by considering moldability and magnetic properties.
115° to 182″″ is preferred.

If the orientation ratio of the magnet is less than 80%, the residual magnetic flux density 3r of the obtained sintered magnet will be less than 4000 (G), which is not preferable, so the orientation ratio is set to 80% or more.

The molded body of the present invention is a so-called right-angle magnetic field brace in which known slurry-like magnet raw material powder or dry magnet raw material powder is compressed and covered in a direction perpendicular to the magnetic field direction by upper and lower bandages of non-magnetic material. It is a molded body by a device.The density of the molded body is preferably 1° from 3.1 to 3.5.Also, if the center angle of the molded body is less than 155°, the sintered body will be sintered to the required 165° or more. 175°
If it exceeds 182°, the center angle of the sintered body will exceed 182°, which will cause cracks and cracks in the sintered body.
55° to 175°.

In the manufacturing method of the present invention, the orientation ratio of the magnetic field radially radially from the center point of the circular arc surface is limited to 80% or more, because if the orientation ratio is less than 80%, I4! This is because the direction of the particles during field molding becomes irregular, resulting in non-uniform magnetic properties and molding density, making it impossible to obtain sufficient magnetic properties, especially Br4000 (G) or higher.

In addition, the load placed on the center of the outer peripheral surface of the molded body is 1
The molded weight 1 (7) 10% to 200%. If it is less than 1 o, the load effect will be small and it will be difficult to control the tensile stress and compressive stress generated on the outer and inner circumferential surfaces of the molded body during sintering, and the center angle will be 182".
If the load exceeds 200%, the molded body will not be able to withstand the load, and the sintered body will crack. In particular, in order to obtain an approximately semicircular sintered body with a center angle of 180', the above load should be 10% to 60% of the molded weight.
% is desirable.

As shown in Fig. 1, the above-mentioned load is placed near the center of the outer circumferential surface of the molded body (1) with its open leg side placed on the plywood for connecting the two legs (3). , Fim thing [2]
When the 2I molded body (1) width (L
) to the load (2)
．． It is preferable to set it to 9L, and when the load is separated from the molded body at the center of the outer peripheral surface of the molded body and contacts the molded body at both ends of the loaded body, it is written as 1=o, i1 to 0.5L. is preferable.

Further, the load may be made of any material such as metal or ceramic as long as it can withstand the sintering temperature of the molded body, or may be a piece of ferrite magnet of the same type as the sintered body. Also,
The shape may be any shape such as an arc shape or a plate shape, but in terms of stability, a shape similar to the shape of the outer peripheral surface of the molded body is preferable.

Further, the sintering temperature of the anisotropic ferrite magnet according to the present invention is preferably 1200°C to 1250°C.

Examples Example 1 Slurry magnet raw powder consisting of 10 wt% SrO and 20390 wt% Fe was processed using a right-angle magnetic field bracing device U.
A molded body of 201[i;l] having dimensions of outer peripheral surface radius 44 mm x 141 field direction thickness 15 mm x center angle 170° x height 20° and weight 100 g was molded under a pressure of 0.5 tJ in an Ed field of 10 koe.

All of the assembled semicircular molded bodies with a density of 3.2 are placed at IL so that the open legs of the molded bodies rest on the sintering base plate, as shown in Figure 1.
Ji, there is an intersection at the center of the outer circumferential surface of the molded body. 3 body (ffi
/L-43%), the Sr fly f1 of 20(]
- Sintering was performed at 1250° C. for 2 hours using the piece as a load to obtain a sintered body. Table 1 shows the center angle and appearance of this sintered body.

In addition, for comparison, the center angle and external appearance of all comparative sintered bodies were prepared using the same material, shape, and sintering conditions, except that WI weight was not placed during sintering of the molded bodies. Research and record it in the TX1 table.

As is clear from Table 1, the ferrite magnet according to the present invention has the required center angle of 180° and has no cracking.

Table 1 also shows that two semicircular anisotropic ferrite magnets obtained according to the present invention were assembled and glued together and processed into dimensions of 70 mm in outer diameter x 48 bars in inner diameter x 16 mm in height, with 6 poles on the inner diameter in the radial direction. As a result of magnetizing the magnet and measuring the orientation rate at each magnetic pole with a rotor flex, the orientation rate was 94% to 96%, with little variation.Furthermore, as a result of measuring the residual magnetic flux density (B'') with a JTSR person, 3r = 4300G, a magnetic flux density characteristic that cannot be obtained with conventional methods was obtained.

Example 2 Slurry magnet 7ζ stone powder consisting of SrO+Owj% and Fe2O3 90wt% was molded using a right-angle magnetic field molding device with CO,5 in a magnetic field of 10 koe under a pressure of 10 koe, outer circumferential surface radius 44 mm x 1 field direction thickness 15 mm x A molded body of ffffioOg with dimensions of 170° center angle x 20° height was molded.

As shown in Fig. 1, all of the semicircular molded bodies with a density of 3.2 are placed on the sintering base plate, and placed in the center of the molded body's outer peripheral surface. , λ, 2/1-1S, FuT
The light single load was varied as shown in Table 2, and sintering was performed for 12 hours at 1250°C under each condition, 50 pieces under each condition, to obtain a sintered body. The center angle, outer diameter of this sintered body,
υ1 Measure the appearance and residual magnetic flux density (B'') of the occurrence rate, and show the results to a second person.

As is clear from the results in Table 2, the center angle (θ) of the semicircular anisotropic ferrite magnet can be arbitrarily set by adjusting the load placed near the center surface of the outer periphery of the molded body.
It can also be seen that the product has excellent appearance and properties.

[Brief explanation of the drawing]

Figure 0'N1 is an explanatory diagram of a semicircular molded body without showing the manufacturing method according to the present invention. 1... Molded body, 2... Load object, 3... Sintering base plate.

Claims (1)

[Claims] 1. Molecular formula: Mo.nFe_2O_3 (M; Ba, Sr,
At least one type of Pb (n: 5.5 to 6.2), approximately semicircular with a center angle θ = 165° to 182°, and with an orientation rate of 80% or more radially from the center point in the radial direction It is made of a molded sintered body with anisotropy of Br and residual magnetic flux density Br
A semicircular anisotropic ferrite magnet characterized by having a power of 4000 (G) or more. 2 Molecular formula Mo・nFe_2O_3(M; Ba, Sr,
consisting of at least one type of Pb, n; 5.5 to 6.2), and having an arcuate shape with a center angle θ = 155° to 175°,
In sintering a molded body having anisotropy with an orientation rate of 80% or more radially from the center point, the open leg side of the molded body is placed on a sintering base plate, and the outer periphery of the molded body is A method for manufacturing a semicircular anisotropic ferrite magnet, characterized in that sintering is carried out while applying a load of 10% to 200% of the molded weight near the center of the surface.