JPH1187163A - Manufacture of rare-earths and iron permanent magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain magnets exhibiting less variations, at low cost in a method for manufacturing permanent magnets in which powders of an alloycomposed of rare-earth metals and iron are bulked by Joule heat obtained from electric conduction. SOLUTION: A mold comprises a nonconductive ceramic dies 1, electrodes 2a and 2b for forming n cavities together wtih the dies 1, and heat-compensating members 3a and 3b. Portions in which a cross section, extending along which pressure is applied less than the total cavity portion are provided in the members 3a and 3b, respectively, so that the object is achieved through conduction at a current which is smaller than a conventional value. In addition, the temperature of the members 3a and 3b is increased more quickly, so that the variations in the speed at which the temperature of powders in the cavities is increased can be compensated for by heat transfer derived from Joule heat produced at the members 3a and 3b. As a result, the equipment cost can be suppressed, and bulked permanent magnets with less variations from one cavity to another can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a bulk permanent magnet from an aggregate of rare earth iron-based alloy powders as a starting material.

[0002]

2. Description of the Related Art Rare earth iron-based alloy powders are classified into magnetically isotropic ones and anisotropic ones. An R-Fe-B-based super-quenched powder sharing an amorphous phase with an R ₂ TM ₁₄ B (R: Nd / Pr, TM: Fe / Co) phase as described in the gazette is exemplified. this is,
The molten rare-earth iron-based alloy is squeezed through a small orifice onto a rotating cold surface and quenched, resulting in a thickness of 20 mm.
It is obtained by subjecting a 薄 30 μm flake to heat treatment as required and then pulverizing. As an anisotropic rare earth iron-based alloy powder,
As shown in JP-A-6-82575, a powder having magnetic anisotropy obtained by subjecting an R-Fe-B-based alloy to a hydrogen storage treatment and a release treatment (hereinafter referred to as HDR powder), Fe-B
Anisotropic bulk magnets obtained by bulking ultra-rapid quenched powders by warm working and then subjecting them to warm plastic working
(See Japanese Patent Application Laid-Open No. 60-100402). In any of these, the powder itself is a useful magnet, but in practice it is necessary to make the powder into a bulk permanent magnet using some means.

[0003] As a conventional technique of using a rare earth iron-based alloy powder as a bulk permanent magnet, as disclosed in Japanese Patent Application Laid-Open No. 59-211549, a resin magnet in which powders are bonded to each other with a resin or Japanese Patent Application Laid-Open No. 60-100402 is disclosed. There is known a hot-pressed magnet as disclosed in Japanese Patent Application Laid-Open Publication No. HEI 10-125, 1988. Further, US Pat. No. 5,167,915 and Japanese Patent Application Laid-Open No. 3-284809 disclose that a cavity is formed by at least one die made of non-conductive ceramic having at least one through hole and a pair of electrodes corresponding to the die. The cavity is filled with a rare earth iron-based alloy powder, a uniaxial pressure is applied to the cross-sectional area in the pressure axis direction of all the electrodes via a pair of heat compensating members, and a current is applied. Is transferred to the powder through all the electrodes, and the powder is heated and pressed to form a rare earth iron-based magnet as a bulk permanent magnet.

[0004]

The relative density of the resin magnet with respect to the alloy is about 80% because the rare earth iron-based powders are bonded to each other with the resin, and it is difficult to further increase the density. On the other hand, hot pressed magnets have a relative density
A bulk permanent magnet of 98-99% can be obtained, which is effective for miniaturization and high output of motors and the like.
It requires a processing temperature of up to 900 ° C. and a processing pressure of 1-3 ton / cm ² . The processing temperature is the temperature range where the R ₂ TM ₁₄ B (R: Nd / Pr, TM: Fe / Co) phase is generated and grows, so the processing temperature, pressure and processing time are accurately controlled. There is a need.

Further, US Pat. No. 5,167,915 and JP-A-3-284809
In the publication, a cavity is formed by at least one die made of non-conductive ceramic having at least one through hole and a pair of electrodes corresponding to the die, and a rare earth iron-based alloy powder is formed in the cavity. Filling, applying uniaxial pressure to the pressure axis cross-sectional area of all electrodes through a pair of heat compensating members, energizing, transferring Joule heat of heat compensating member generated by energization to powder through all electrodes A method for manufacturing a rare-earth iron-based magnet in which powder is heated and pressed to form a bulk permanent magnet is disclosed, and the ρ / sc (ρ is specific resistance Ωcm, s is specific gravity, c is specific heat) value of the electrode is minus 10. 4th power level, ρ / sc of thermal compensation member
It is shown that when the value is set to the level of minus 10 to the power of 3, the fluctuation of the heating rate due to the non-uniformity of the current flowing through the cavity group can be compensated by the heat conduction from the heat compensation member. In this case, it is necessary to conduct DC current at a current density of 250 to 300 A per square cm with respect to the cross section in the pressure axis direction of all cavities, when manufacturing a bulk permanent magnet having a large cross section in the pressure axis direction, or When the number of cavities is increased, there is a problem that the required current capacity of the power supply is increased, so that the equipment cost is increased and the power consumption is increased.

The present invention relates to an improvement in a method for manufacturing a rare-earth iron-based magnet to solve the above problems.

[0007]

According to the present invention, a cavity is formed by at least one die made of a non-conductive ceramic having at least one through hole and a pair of electrodes corresponding to the die. Is filled with a rare earth iron-based alloy powder to which a binder is added as necessary, and the powder filled in the cavity portion is magnetically oriented as necessary, and then the pressure axis direction of all electrodes is passed through a pair of heat compensating members. Applying uniaxial pressure to the cross-sectional area, energizing it, transferring the Joule heat of the heat compensating member generated by the energization to the powder through all the electrodes, heat-compressing the powder, and forming a bulk permanent magnet A method of manufacturing a rare-earth iron-based magnet, characterized in that the heat compensating member is provided with a portion having a cross-sectional area in the pressure axis direction equal to or smaller than the cross-sectional area in the pressure axis direction of the entire cavity.

The advantage of the present invention is that the heat-compensating member has a pressure-axis cross-sectional area of less than or equal to the pressure-axis cross-sectional area of the entire cavity portion.
By conducting electricity at a current density of 50 to 300 A, the Joule heat of the heat compensating member generated by the conduction is transferred to the rare-earth iron-based alloy powder through all the electrodes, and the powder is heated and pressed to form a bulk permanent magnet. It is possible to do it. Conventionally, USP
5,167,915 and JP-A-3-284809 require direct current at a current density of 250 to 300 A per square cm with respect to the cross section in the pressure axis direction of the entire cavity, and a bulk permanent magnet having a large cross section in the pressure axis direction is required. When a magnet is manufactured or the number of cavities is increased, the current value at the time of energization is increased, and the required current capacity of the power supply is increased, thereby increasing equipment costs and power consumption. There was a problem.

According to the present invention, the heat-compensating member has a cross-sectional area in the pressure axis direction which is smaller than the cross-sectional area in the pressure axis direction of the entire cavity portion.
DC current at a density of only one, and the required current capacity of the power supply can be small, which can reduce equipment costs.
Power consumption can be reduced. Further, by providing the heat compensating member with a portion whose sectional area in the pressure axis direction is equal to or smaller than the sectional area in the pressure axis direction of all the cavities, the rate of temperature rise of the heat compensating member is higher than the rate of temperature rise of the powder filled in the cavity. It is possible to effectively compensate for fluctuations in the heating rate due to the non-uniformity of the current flowing through the cavity group by heat conduction from the heat compensating member. According to this invention, 600 ° C.
At a processing temperature lower than the hot press method of 00 ° C and a processing pressure lower than the hot press method of 200 to 500 kgf per square cm, the relative density of 98 to 99% bulk permanent magnets can be produced. In addition, productivity is further improved by adopting a configuration in which the dies and electrodes forming the cavity group are stacked in multiple stages in the pressure axis direction via the heat transfer member.

[0010]

DETAILED DESCRIPTION OF THE INVENTION The invention as set forth in claim 1 of the present invention is directed to a method of manufacturing a semiconductor device comprising at least one die made of non-conductive ceramic having at least one through hole and a pair of electrodes corresponding to the die. Is formed, and the cavity is filled with a rare earth iron-based alloy powder to which a binder is added as necessary.
If necessary, after the powder filled in the cavity is magnetically oriented, a uniaxial pressure is applied to the cross-sectional area in the pressure axis direction of all the electrodes through a pair of heat compensating members, and a current is applied. In a method of manufacturing a rare earth iron-based magnet that transfers Joule heat to powder through all electrodes and heat-presses the powder to form a bulk permanent magnet, the heat compensation member has a pressure axis cross-sectional area of the pressure axis of all cavities. The current compensating part is provided with a part whose cross-sectional area is smaller than the cross-sectional area in the pressure axis direction. And the current density (I / S) in the part concerned is relatively increased from the current density in the whole cavity part, and 1W =
0.2389 (cal / sec), I: energizing current (A), R: electric resistance (Ω), C:
Heat capacity (cal / ° C), ρ: specific resistance (Ωcm), s: specific gravity, c: specific heat (ca
l / ℃ g), S: when the compression axis direction cross-sectional area (cm ^2), ΔT /
Δt = 0.2389I ² R / C = (0.2389ρ / sc) (I / S) The temperature rise rate by Joule heat at the time of energization expressed by ² is faster than that of the powder filled in the cavity, and the contact resistance etc. Has the effect of compensating for the variation in the temperature rise of the powder in each cavity caused by the current flowing through the plurality of cavities, which is not necessarily evenly distributed to the plurality of cavities, by the heat transfer by the Joule heat of the pair of heat compensating members.

According to a second aspect of the present invention, in the heat compensating member, the specific resistance of the material of the portion having a cross-sectional area in the pressure axis direction equal to or less than the cross-sectional area in the pressure axis direction of all the cavities is made higher than the other portions. By doing so, it is possible to increase the rate of temperature rise in the part, reduce undesirable temperature unevenness in the heat compensating member, stabilize the quality of the bulk permanent magnet, and improve the durability of the heat compensating member. Has an action.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

(Example 1) FIG. 1 shows an example of the configuration of a molding die according to an example of the present invention. The magnetic properties of an isotropic or anisotropic or an isotropic and anisotropic rare earth iron-based alloy powder are shown. FIG. 3 is an external view of a main part of a bulk permanent magnet that can be manufactured with high dimensional accuracy while maintaining the above conditions. FIG.
It is AB sectional drawing. In FIG. 1, reference numeral 1 denotes a non-conductive ceramic die, a plurality of which are arranged so as to form a circumference.
2a and 2b are a pair of electrodes, and the same number as the non-conductive ceramic die 1 is arranged corresponding to each.
Here, the electrodes 2a and 2b form a cavity together with the non-conductive ceramic die 1, and each serves as an electrode and also serves as an upper and a lower punch.

It is desirable that the cavity surfaces of the pair of electrodes 2a and 2b be covered with a layer containing boron nitride powder as an active ingredient. Reference numerals 3a and 3b denote heat compensating members provided with portions whose sectional area in the pressure axis direction is equal to or smaller than the sectional area in the pressure axis direction of all cavities. FIG. 2 is a cross-sectional view taken along the line AB in FIG. 1, and reference numeral 4 denotes a rare earth iron-based alloy powder. As the rare earth iron-based alloy powder, magnetically isotropic or anisotropic one can be used.
As an isotropic rare earth iron-based alloy powder, for example,
As shown in JP-A-59-64739, R ₂ TM ₁₄ B (R: Nd / Pr, T
An R-Fe-B-based super-quenched powder sharing an (M: Fe / Co) phase and an amorphous phase can be used. This is obtained by squeezing the molten rare-earth iron-based alloy onto a rotating cold surface through a small orifice, quenching it, heat-treating the obtained flakes having a thickness of 20 to 30 μm if necessary, and then pulverizing the flakes. Further, as the anisotropic rare earth iron-based alloy powder, as shown in Japanese Patent Publication No. 6-82575, a powder obtained by subjecting an R-Fe-B-based alloy to a hydrogen storage treatment and a release treatment (hereinafter referred to as a powder). HDD
R powder), or R-Fe-B-based super-quenched powder, after being bulked by warm working, etc., and further subjected to warm plastic working to obtain an anisotropic bulk magnet (Japanese Patent Application Laid-Open No. 60-100402). And the like can be used. When using anisotropic rare-earth iron-based alloy powder, the magnetic field is oriented after filling the cavity, and the easy axis of magnetization of the anisotropic rare-earth iron-based alloy powder is aligned, so that the magnetic properties of the bulk permanent magnet The characteristics are improved. Furthermore, rare earth iron-based alloy powders include:
If necessary, a binder such as a metal such as Zn or a low-melting glass containing MgO, ZrO, or PbO may be added.

The plurality of cavities are preferably arranged at equal intervals on the circumference, and the inner and outer diameters of the cylindrical heat compensating member are desirably concentric with the circumference on which the cavities are equally arranged.

Next, the operation of the present invention will be described with reference to the mold having the above configuration. First, under reduced pressure of 0.1 to 0.001 Torr, all the electrodes 2a, 2b are pulled from both end surfaces of the pair of heat compensating members 3a, 3b.
A pressure of 200 to 500 kgf per square centimeter is applied to the rare-earth iron-based alloy powder 4 with respect to the cross section in the pressure axis direction of the cavity portion through. Thereby, the potential energy between the individual particles of the rare-earth iron-based alloy powder 4 decreases.

Next, a pulse energization process is performed on the rare-earth iron-based alloy powder 4. The pulse current treatment has an etching effect of reacting with contaminants and low molecular compounds adhering to the powder surface, thereby further reducing the potential energy between the individual rare earth iron-based alloy powders 4.

After the above-described pulse energizing treatment, while maintaining a constant vacuum atmosphere and pressure on the rare-earth iron-based alloy powder 4, all the electrodes 2a, 2b are applied from both end surfaces of the pair of heat compensating members 3a, 3b. To the rare-earth iron-based alloy powder 4 through the heat-compensating members 3a, 3b with respect to the portions 3aa, 3bb whose cross-sectional area in the pressure axis direction is equal to or less than the cross-sectional area in the pressure axis direction of all cavities. Energize at a current density of 300A.
The temperature rise rate of each member when energized is 1W = 0.2389 (cal / sec), I:
Current (A), R: Electric resistance (Ω), C: Heat capacity (cal / ° C), ρ:
When specific resistance (Ωcm), s: specific gravity, c: specific heat (cal / ° C g), and S: cross-sectional area in the pressure axis direction (cm ² ), ΔT / Δt = 0.2389I ² R / C =
(0.2389ρ / sc) (I / S) ² That is, the heating rate ΔT / Δt is (I / S) 2ρ / sc, which is proportional to the square of the current density (I / S) and the specific resistance ρ (Ωcm), and the specific heat c (cal / ° C.g) and the specific gravity. Is inversely proportional to Here, by providing the heat compensating members 3a and 3b with portions 3aa and 3bb whose cross-sectional area in the pressure axis direction is smaller than the cross-sectional area in the pressure axis direction of the entire cavity portion, the current density in the corresponding portions is relatively higher than that in the cavity portion. And the temperature rise rate of the part can be made faster than that of the cavity part, and the joule of the powder in each cavity caused by a current flowing through the plurality of groups of cavities that is not always uniformly distributed due to the influence of contact resistance and the like. Variations in the heating rate due to heat can be compensated for by the heat transfer of the pair of heat compensating members 3a and 3b due to Joule heat. As a result, a uniform heating rate of the rare-earth iron-based alloy powder 4 in each cavity can be secured. The rare-earth iron-based alloy powder 4 in each cavity whose heating rate is controlled by the transfer of Joule heat due to the above-described energization, particularly the heat transfer of the Joule heat of the heat compensating members 3a and 3b.
Are thermocompressed to form a bulk permanent magnet. Even when the magnetic field orientation is performed, thermal demagnetization is performed by increasing the temperature during energization, so that demagnetization of the bulk permanent magnet is unnecessary.

The maintenance of the compression pressure and the vacuum atmosphere after the interruption of the conduction current is performed at least until the temperature of the outer surface of the die made of non-conductive ceramics starts to cool. Here, the fact that the die is non-conductive means that the thermal conductivity is small, which is effective in suppressing the flow of current and heat and increasing the thermal efficiency.

More specifically, an isotropic rare earth iron-based alloy powder (trade name: MQP-C, Magnequench International I
nc.) and anisotropic rare earth iron-based alloy powder (trade name MQA-T, Mag
nequench International Inc.), weigh appropriately,
The cavity group having the configuration shown in FIG. 1 was filled. In FIG. 1, 1
Is a die made of non-conductive ceramic provided with a through-hole having a diameter of 25 mm, and 2a and 2b are a pair of electrodes corresponding to the through-hole of the die 1 made of non-conductive ceramic. However,
Here, the number n of the die and the electrode pair is 6, and the sectional area in the pressure axis direction of all the cavity portions is 29.5 cm ² . The material of the die 1 is sialon, and the material of the electrodes 2a and 2b is a cemented carbide (JIS H5501 G5). A boron nitride powder layer was provided on the surfaces of the electrodes 2a and 2b on the cavity side. 3a, 3
b denotes a pair of heat compensating members arranged on the anti-cavity surfaces of all the electrodes comprising a pair of electrodes 2a and 2b and a through-hole of the die 1 made of non-conductive ceramics and forming a plurality of six cavities. A portion having an axial sectional area of 10 cm 2 was provided. The material of the heat compensating member is graphite.

FIG. 2 is a cross-sectional view taken along the line AB of FIG. 1, and reference numeral 4 denotes a rare earth iron-based alloy powder. The rare earth iron-based alloy powder 4 was subjected to magnetic field orientation, and the axes of easy magnetization of the anisotropic rare earth iron-based alloy powder were aligned. Next, the mold is placed in a reduced-pressure atmosphere of 0.1 to 0.001 Torr, and a pressure of 250 kgf per square centimeter with respect to a section in the pressure axis direction of the powder 4 in the cavity is passed through the pair of heat compensating members 3a and 3b and all electrodes. And compressed. Then, the heat compensating member 3a,
Pulse current was applied by applying a DC voltage of 10 mV and a pulse width of 300 msec to the powder 4 in the cavity through the electrode 3b and all the electrodes for 90 seconds. Subsequently, while maintaining the decompressed atmosphere and the compression pressure, the pressure compensating members 3a and 3b have a sectional area in the pressure axis direction smaller than the sectional area in the pressure axis direction of all the cavities by 1 cm 2 with respect to the sectional area of the portions 3aa and 3bb. 300A per
DC current is applied at the current density of, and the displacement amount of the powder 4 in the cavity that is pressurized and compressed in the pressure axis direction is detected,
The strain rate obtained by differentiating the time was continuously measured. The strain rate increases as the temperature of the powder 4 in the cavity increases, but decreases as the powder 4 in the cavity becomes more compact. In the process of decreasing the strain rate,
When the current is cut off at a strain rate of 0.003 to 0.006 mm / sec and the outer surface temperature of the die 1 made of non-conductive ceramics becomes 400 ° C. or less, the decompression atmosphere and the compression pressure are released, and after cooling as appropriate. The magnet was released. By this operation, the diameter is 25mm and the height is 7.4m directly from the rare earth iron based alloy powder 4.
m bulk permanent magnets were obtained.

With the above-described configuration, the current value at the time of direct current is applied to the portions 3aa, 3aa, 3a, 3b in which the cross-sectional area in the pressure axis direction of the heat compensating members 3a, 3b is smaller than the cross-sectional area in the pressure axis direction of all cavities. The product of the cross-sectional area of 3 bb of 10 cm 2 and the current density is 2500 to 3000 A. However, when the present invention is not applied, the current value at the time of direct current application is the product of the cross-sectional area in the pressure axis direction of all the cavity portions and the current density, and is 7375 to 8850A.

As described above, in the present invention, the heat compensating members 3a, 3a
The sectional area of the portions 3aa and 3bb whose sectional area in the pressure axis direction of 3b is smaller than the sectional area in the pressure axis direction of all the cavities
DC current at a density of 250 to 300 A per square centimeter is sufficient, and the required current capacity of the power supply can be smaller than before so that equipment costs can be reduced and power consumption can be reduced.

(Example 2) Isotropic rare earth iron-based alloy powder
(Trade name MQP-C, manufactured by Magnequench International Inc.)
Anisotropic rare earth iron-based alloy powder (trade name MQA-T, Magnequench I
nternational Inc.) was mixed, weighed appropriately, and filled in the cavity group having the configuration shown in FIG. In FIG. 1, 1 is 25 mm in diameter.
A die made of non-conductive ceramics provided with through holes of
2a and 2b are a pair of electrodes corresponding to the through holes of the die 1 made of non-conductive ceramics. However, here, the number n of the die and the electrode pair is 6, and the sectional area in the pressure axis direction of all the cavity portions is 29.5 square cm. The material of the die 1 is sialon, and the material of the electrodes 2a and 2b is a cemented carbide (JIS H
5501 G5). A boron nitride powder layer was provided on the surfaces of the electrodes 2a and 2b on the cavity side. 3a and 3b are a pair of electrodes 2a and 2b and a die 1 made of non-conductive ceramics.
Electrodes 2a, 2a comprising six cavities with
b, a pair of heat compensating members arranged on the anti-cavity surface, and a portion 3aa having a sectional area of 10 square cm in the pressure axis direction.
3bb was provided. The material of the portions 3aa and 3bb in which the cross-sectional area in the pressure axis direction of the heat compensating members 3a and 3b is equal to or smaller than the cross-sectional area in the pressure axis direction of the entire cavity portion is made of graphite having a specific resistance of 1.55 mΩcm. 10μΩcm
94W-4Ni-2Cu tungsten alloy.

FIG. 2 is a cross-sectional view taken along the line AB in FIG. 1, and reference numeral 4 denotes a rare earth iron-based alloy powder. Next, the above mold is 0.1 to 0.001
A pair of heat compensating members 3a, 3
b, powder 4 in the cavity through all electrodes 3a, 2b
Was compressed at a pressure of 250 kgf per square cm with respect to the pressure axial section. Then, while maintaining the decompressed atmosphere and the compression pressure constant, the pulse current is applied by applying a DC voltage of 300 msec and 10 V for 90 sec to the powder 4 in the cavity through the heat compensating members 3a and 3b and all the electrodes 2a and 2b. Was done. Then, while maintaining the reduced pressure atmosphere and the compression pressure,
Parts 3aa, 3bb in which the cross-sectional area in the pressure axis direction of the heat compensating members 3a, 3b is smaller than the cross-sectional area in the pressure axis direction of all the cavities.
DC current is applied at a current density of 300 A per square cm with respect to the cross-sectional area of, and the amount of displacement of the powder 4 in the cavity that is compressed and compressed in the pressure axis direction is detected, and the strain rate obtained by differentiating it with time is calculated. Measured continuously. The strain rate increases with increasing temperature of the powder in the cavity, but decreases as the powder consolidation proceeds. In the process of decreasing the strain rate, the current was cut off within the strain rate range of 0.003 to 0.006 mm / sec, and when the outer surface temperature of the die 1 made of non-conductive ceramics became 400 ° C. or less, the reduced pressure atmosphere was applied. And the compression pressure was released, and after cooling as appropriate, the magnet was released.

By this operation, the rare-earth iron-based alloy powder 4
Directly obtained six bulk permanent magnets having a diameter of 25 mm and a height of 7.4 mm. With the configuration shown here, the energization time during DC energization is shorter than in the first embodiment, and the unfavorable temperature unevenness in the heat compensator, ie, the temperature difference in the pressure axis direction, is lower than in the first embodiment. Temperature non-uniformity other than the above was able to be reduced. Further, the durability of the heat compensating member was also improved.

[0027]

As described above, according to the first aspect of the present invention, when the heat compensating member is provided with a portion having a cross-sectional area in the pressure axis direction smaller than the cross-sectional area in the pressure axis direction of all the cavities, the heat compensating member is required for direct current application. And the current value
The current density in this part is relatively higher than the current density in all cavities, and the rate of temperature rise due to Joule heat during energization is faster than that of the powder filled in the cavities. Variations in powder temperature rise in each cavity due to a current flow that is not necessarily evenly distributed to the group of cavities are compensated by heat transfer by Joule heat of a pair of thermal compensation members, stabilizing the quality of the bulk permanent magnet Has the advantageous effect of causing

According to a second aspect of the present invention, in the heat compensating member, the specific resistance of the material of a portion having a cross-sectional area in the pressure axis direction equal to or smaller than the cross-sectional area in the pressure axis direction of all the cavities is made higher than the other portions. By doing so, it is possible to increase the rate of temperature rise in the part, reduce undesirable temperature unevenness in the heat compensating member, stabilize the quality of the bulk permanent magnet, and improve the durability of the heat compensating member. An advantageous effect is obtained.

[Brief description of the drawings]

FIG. 1 shows a configuration example of a mold according to the present invention.

FIG. 2 is a cross-sectional view taken along a line AB in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Die 2a, 2b Electrode 3a, 3b Heat compensating member 3aa, 3bb Part whose cross-sectional area in the pressure axis direction is less than or equal to cross-sectional area in the pressure axis direction of all cavities 4 Rare earth iron-based alloy powder

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masami Wada 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (2)

[Claims] 1. A cavity is formed by at least one die made of non-conductive ceramic having at least one through hole and a pair of electrodes corresponding to the die, and coupled to the cavity as required. After adding the rare-earth iron-based alloy powder to which the additive has been added and, if necessary, orienting the powder filled in the cavity in a magnetic field, a uniaxial pressure is applied to the cross-sectional area in the pressure axis direction of all the electrodes via a pair of heat compensating members. In addition, a method of manufacturing a rare earth iron-based magnet, which is energized, transfers the Joule heat of the heat compensating member generated by the energization to the powder through all the electrodes, heat-compresses the powder, and forms a bulk permanent magnet, A method of manufacturing a rare-earth iron-based magnet, wherein a portion having a sectional area in the pressure axis direction equal to or smaller than a sectional area in the pressure axis direction of all cavities is provided in the compensating member. 2. The heat compensating member, wherein a portion of the material having a sectional area in the pressure axis direction smaller than that of the cavity in the pressure axis direction has a higher specific resistance than other parts. 2. The method for producing a rare earth iron-based magnet according to 1.