JP2830125B2 - Manufacturing method of anisotropic rare earth magnet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the invention]

(Industrial Application Field) The present invention relates to a method for producing an anisotropic rare earth magnet, and more specifically, R-Fe- represented by an Nd-Fe-B-based magnet.
The present invention relates to a method for producing a B-based (R is a La-based rare earth metal, Fe represents a transition metal, and B represents another property improving metal) anisotropic permanent magnet. (Prior art) R-Fe-B permanent magnets include: (a) a base material alloy is melted and cast into a mold to form an ingot, which is pulverized into an ultrafine powder; In (2), a sintered magnet formed into a compact by using a mold and sintered to make it anisotropic; and (b) a melt of a base material alloy is super-quenched to form a ribbon, and the coarsely pulverized powder is used as it is or for example. As shown in FIG. 4 (a), once cold compacting (forming pressure, for example, 4 ton / c
m ² ) to obtain a preformed body 51 having a theoretical density ratio of about 80%, and using this preformed body 51, hot pressing is performed at a temperature of about 700 ° C. by a die 52 and an upper punch 53 shown in FIG. (Pressing pressure, for example, 1 ton / cm ² ) to obtain an isotropic magnetic material 54, which is reduced at a temperature of 900 ° C. or less by another die 55 and an upper punch 56 shown in FIG. And a super-quenched magnet using a super-quenched magnet material 5 anisotropically subjected to plastic deformation processing (extruding pressure, for example, 4 ton / cm ² ) having an area ratio of 40% or more. (Problems to be Solved by the Invention) These magnets having high magnetic properties are extremely useful in reducing the size and weight of motors, especially if they can be applied to small motors for OA and FA equipment. At present, however, there is a problem in practical application technology, and the fact is that it has not been sufficiently applied to motors. In order to apply the rare-earth magnet to these motors, it is most preferable to use a thin sleeve-shaped or ring-shaped magnet which is magnetically anisotropic in the radial direction. It is difficult to apply a magnetic field in the radial direction when forming by molding, so the degree of anisotropy is about 50 to 60% lower than that of a plate magnet, and the anisotropic material is sintered There is a problem that cracks easily occur due to anisotropic thermal expansion due to heating and cooling at the time. On the other hand, the latter super-quenched magnet does not require molding in a magnetic field and performs anisotropy by plastic deformation. Therefore, even in the case of the above-mentioned sleeve-shaped or ring-shaped magnet, the anisotropy can be maximized. However, the theoretical density ratio is 99% due to the isotropy of the die 52 and the upper punch 53 shown in FIG. 4B, for example.
Two heats of forming the material 54 and forming anisotropically by performing plastic deformation with the die 55 and the upper punch 56 shown in FIG. 4C are required. The magnetism is sensitive to crystal grains, and there is a problem that magnetism decreases when the crystal grains are coarsened by heating for a long time. In addition, since this material is extremely brittle, when the material is formed into a sleeve shape or a ring shape by extrusion, a large forming crack 58 as shown in FIG. 4 (c) occurs. (Object of the Invention) The present invention relates to the latter ultra-quenched magnet, which is formed into a sleeve-shaped or ring-shaped ring-shaped annular cross section by heating with one heat to obtain a highly magnetic anisotropic magnet.
Further, the purpose of the present invention is to reduce the cost of the mold by one set of the molds and to prevent the mold cracking.

Configuration of the Invention

(Means for Solving the Problems) According to a method for manufacturing an anisotropic rare earth magnet according to the present invention, a die having openings at both ends and an opening on one side of the die are provided as described in claim (1). A double punch having a sleeve punch slidable on the outer peripheral surface along the inner peripheral surface of the die and a core punch slidable on the outer peripheral surface along the inner peripheral surface of the sleeve punch; A double-acting punch having a die, a sleeve punch, and a core punch, and a double-acting punch; Using a forming die in which a forming space is formed between the preform and the preformed body obtained by ultra-quenching the base metal alloy of the rare earth magnet to form a ribbon, and cold-compacting the powder obtained by pulverizing the ribbon. Preheated to 650-900 ° C in the molding space Then, the preform is uniformly pressed and compressed until the density of the preform becomes 99% or more of the theoretical density between the sleeve punch and the core punch forming the double-acting punch and the opposing punch. Of the double-acting punches, the pressurization by the sleeve punch is stopped, the pressure is compressed between the core punch and the opposing punch, and the cross-section is annular by extruding between the inner peripheral surface of the die and the outer peripheral surface of the core punch. Characterized in that the anisotropic rare earth magnet is manufactured by one heat heating. Further, in the invention described in claim (2), in the method described in claim (1), instead of using the pre-compacted body formed by cold compaction, the raw material powder is formed in the molding space. The double punch is pre-heated to 650 to 900 ° C. to form a double-acting punch, and is uniformly pressed and compressed between the core punch and the opposing punch. Further, in the invention described in claim (3), in the method described in claim (1) or (2), instead of stopping the pressurization by the sleeve punch, the method uses the sleeve punch. A structure in which a pressing force lower than the pressing and compressing force is applied to the end face of the material to be pressed and compressed between the core punch and the opposing punch and extruded between the inner peripheral surface of the die and the outer peripheral surface of the core punch. It is characterized by having. Furthermore, in the invention described in claim (4), in the method described in claim (1), (2) or (3), the pressure compression and the extrusion molding are performed at 1 Torr. It is characterized in that the process is performed under a lower pressure vacuum or an inert gas atmosphere. Furthermore, in the invention described in claim (5), in the method according to claim (1), (3) or (4), the material powder is cold compacted. In order to improve the lubricating ability between the molding die and the powder grains, a preform is formed by mixing a lubricant such as lithium stearate at 2% by weight or less to improve the green density. It is characterized by having a body configuration. In the method for producing an anisotropic rare earth magnet according to the present invention, as described above, the cold compacted preform (in the case of claim (1)) or the raw material powder (in the case of claim (2)) 650 to 900 using a two-action double-acting punch having a core punch and a sleeve punch.
In the first step, the material heated to 0 ° C. is subjected to the same operation for both punches, that is, by operating both punches as a unit, thereby uniformly pressing and compressing the material with the opposing punch to obtain a theoretical density ratio. After obtaining a green compact of 99% or more of magnetically isotropic solid or hollow compact, as a second step in the same mold, without reheating, using a sleeve punch among double acting punches The pressing is stopped, the pressure is compressed between the core punch and the opposing punch, and the extrusion is performed between the inner peripheral surface of the die and the outer peripheral surface of the core punch (that is, the space formed by the retreat of the sleeve punch). In this way, an anisotropic rare earth magnet material having an annular cross section in the shape of a sleeve or a ring is obtained, and then magnetized appropriately to form an anisotropic rare earth permanent magnet. . In this second step, the sleeve punch may be completely retracted from the end face of the work material, but as described in claim (3), the work is performed at a constant pressure lower than the pressurizing compression force. By keeping the end face of the material pressed, the occurrence of forming cracks can be more reliably prevented. Further, as described in claim (4), it is more preferable that these moldings are performed under a vacuum at a pressure lower than 1 Torr or under a heating at 650 to 900 ° C. in an inert gas atmosphere. In the R-Fe-B magnet to which the present invention is applied, R is
La-based rare earth element represented by Nd. This magnet has a small amount of Co, Dy ₂ O ₃ , Ga and other substances for improving magnet properties, Ni, Zn, Pb, Al and other corrosion resistance. It goes without saying that a substance for improving heat resistance and workability can be contained. In the method for producing an anisotropic rare earth magnet according to the present invention, a green compact formed of a magnetically isotropic solid or hollow material is formed by using a raw material powder or a preform obtained by cold compacting the same. It is molded and subsequently extruded to form a magnet material having an annular cross section such as a sleeve or a ring, and the extrusion method at this time may be either backward extrusion or forward extrusion. It is possible. In these molding processes, in the conventional case, in the first step, the powder or its preform is heated and compressed to form a magnetically isotropic green compact, and in the second step, it is reheated to form another compact. It is extruded in a mold to form a magnetically anisotropic sleeve or ring-shaped annular cross section. However, in the conventional case, the magnetic properties of this material deteriorate due to the growth of crystal grains due to long-time heating. Accordingly, the present invention provides a magnetically anisotropic sleeve-shaped or ring-shaped permanent magnet having a ring shape in one heat and one set of molds by using a double action punch of a core punch and a sleeve punch. It was done. Further, in the extrusion in the second step, the generation of cracks in the molding can be more effectively prevented by applying and maintaining a constant processing compression to the free surface of the end face of the processing material by the sleeve punch. FIG. 1 shows an embodiment of a method for producing an anisotropic rare earth magnet according to the present invention, in which a base metal alloy of a rare earth magnet is rapidly quenched into a ribbon, and powder obtained by pulverizing the ribbon is preformed. Then, a preformed body cold-formed by a conventional powder molding method is prepared. The density of this preform is 70 to 80 in theoretical density ratio.
%, And about 80% according to a general molding method. This preform is pre-formed by a heating method (not shown).
Preheat to 650-900 ° C, more preferably 700-800 ° C. Next, as shown in FIG. 1 (a), the preform 1 is formed into a molding space of a molding die 7 including a die 2, a double-acting punch 5 having a core punch 3 and a sleeve punch 4, and an opposing punch 6. 7a, at this time, the mold 7 is also 600-900 ° C., more preferably 700-800 ° C. by a method not shown.
Preheat. When the preform 1 is small, only the mold 7 may be preheated, and the preform 1 may be heated by the heat transfer from the mold 7, or when the preform 1 is large. In some cases, only the preform 1 is preheated and the mold 7 can be molded at room temperature. Further, instead of the preform 1, the raw material powder can be set in the molding space 7 a of the molding die 7 as it is. Also, all of them are held in a sealed tank, and the atmosphere in the tank is evacuated to a pressure lower than 1 Torr, or filled with an inert gas such as argon gas to provide an antioxidant atmosphere as required. preferable. Next, the core punch 3 and the sleeve punch 4 of the double-acting punch 5 are integrally pressed down such that their tip surfaces 3a, 4a are flush with each other, and the preform 1 is uniformly pressed with the opposing punch 6. By compressing, as shown in FIG.
A pressed material 9 is obtained. The pressurizing pressure at this time is 0.5
It is preferable to provide about 2.0 ton / cm ² , more preferably 1 to 1.5 ton / cm ² . As a result, a green compact material (columnar isotropic magnet material) 9 having a theoretical density ratio of 99% or more is obtained. Next, as shown in FIG. 1 (c), the pressing by the sleeve punch 4 of the double-acting punch 5 is stopped and the core punch 3 is pressed.
Only the core punch 3 and the opposing punch 6 are pressed and compressed, and the inner peripheral surface of the die 2 and the core punch 3 are compressed.
Is extruded backward to form an anisotropic rare-earth magnet material 10 having a sleeve-like annular cross-section. The extrusion pressure at this time is preferably ² to 5 ton / cm ² , more preferably 3 to 4 ton / cm ^{2 in} terms of punch surface pressure. In this backward extrusion, it cannot be said that a molding crack does not occur on the inner surface. Therefore, a pressing force is applied to the upper end face 10b by the sleeve punch 4 in the direction indicated by the arrow in FIG. By applying a stress, the occurrence of the crack can be more reliably prevented. The compression force at that time is 0.2 to 1.0 by pressure
ton / cm ^2, more preferably it is give 0.4~0.6ton / cm ^2. After the end of the extrusion molding, the opposing punch 6 is lifted to knock out the sleeve-shaped anisotropic rare-earth magnet material 10 from the mold 7, and the bottom 10a is separately cut and removed, and then magnetized in the radial direction. An anisotropic rare earth magnet is obtained. In the method of manufacturing an anisotropic rare earth magnet according to the present invention, in addition to the backward extrusion described above, the extrusion molding method can be used.
Description will be made based on the drawings. In the forming die 7 shown in FIG. 2, the sleeve punch 4 of the double-acting punch 5 has its inner peripheral surface slidably fitted on the outer peripheral surface of the core punch 3, as shown in FIG. 2 (a). First, the tip surface 3a of the core punch 3 and the tip surface 4a of the sleeve punch 4 are kept aligned, and the die 2
The preform is set in the molding space 7a, and then the opposing punch 6 is pressed down to uniformly press and compress the core punch 3 and the sleeve punch 4 (that is, the double-acting punch 5). The green compact 9 having a ratio of 99% or more. Next, as shown in FIG. 2 (b), the opposing punch 6 is depressed with only the core punch 3 for which pressurization by the sleeve punch 4 is stopped being fixed, and the pressure between the opposing punch 6 and the core punch 3 is increased. The powder compact 9 is formed into a sleeve-shaped anisotropic rare-earth magnet material 10 while being compressed and simultaneously extruded forward between the inner peripheral surface of the die 2 and the outer peripheral surface of the core punch 3. In this case, the lower end surface of the anisotropic rare earth magnet material 10
By applying a constant compressive force to the sleeve 10b by the sleeve punch 4, the occurrence of forming cracks can be prevented more reliably. By the way, in forming the anisotropic rare earth magnet material 10 which is a sleeve-shaped molded product, in order to generate sufficient magnetic anisotropy in the radial direction, the extrusion area reduction rate should be 40 to 80.
%, More preferably 55-65%. Therefore, in order to obtain a thin sleeve, a cylindrical preform 1 as shown in FIGS. 1 and 2 is used as a magnet material.
If a material made of such a material is used, the extrusion area reduction rate may be too large. Therefore, in such a case, the preform 1 having a thick cylindrical shape may be used as the material as shown in FIG. That is, as shown in FIG. 3 (a), a die 2, a double-acting punch 5 having a core punch 3 and a sleeve punch 4,
A preform 1 formed of a thick cylindrical cold compact is set in a molding space 7a of a molding die 7 having an opposing punch 6, and then, as shown in FIG. The core punch 3 and the sleeve punch 4 are simultaneously pressed down and uniformly pressed and compressed between the opposing punches 6 to obtain a green compact 9 which is an isotropic magnet material having a theoretical density ratio of 99% or more. Get. At this time, the core punch 3 is a thick cylindrical preform 1
The small diameter portion 3b of the core punch 3 is inserted into the green compact 9 as shown in FIG. 3 (b). Has become. The opposite punch 6 has a small-diameter portion 3b of the co-punch 3
There is provided a hollow portion 6b for receiving the pressure. Next, as shown in FIG. 3 (c), the pressurization by the sleeve punch 4 of the double-acting punch 5 is stopped, and only the core punch 3 is depressed to pressurize between the core punch 3 and the opposing punch 6. While being compressed, backward extrusion is performed between the inner peripheral surface of the die 2 and the outer peripheral surface of the core punch 3 to extrude the anisotropic rare earth magnet material 10 which is a thin-film sleeve-shaped molded product. During this time, if a constant compressive force of the sleeve punch 4 is applied to the end face 10b of the anisotropic rare earth magnet material 10, the occurrence of molding cracks can be more reliably prevented, but molding is possible without applying pressure. It is. (Effect of the Invention) In the method for producing an anisotropic rare earth magnet according to the present invention, which has the above-described configuration, it is not necessary to perform molding in a magnetic field, and the anisotropy is performed by plastic deformation. When an anisotropic ultra-quenched magnet that is magnetized later is formed into a sleeve or ring-shaped annular cross section, an anisotropic rare-earth magnet having high magnetic properties can be manufactured by one heat heating. Example 1 A 20 μm-thick ribbon obtained by ultra-quench-cooling a base metal alloy of a rare-earth magnet having a composition of Nd _13.5 Fe _80.5 B _6.0 is pulverized into a flake-like powder having a size of about 200 μm. I got Next, after uniformly mixing 0.5% by weight of lithium stearate with the powder, the outer diameter of the powder was adjusted using a conventional powder molding press.
A cylindrical preform having a height of 9.5 mm and a height of 25 mm was obtained. Subsequently, the preform was vacuum-degreased to 10 ^-2 To using a conventional vacuum degreasing furnace.
Lithium was degreased at a temperature of 450 ° C. for a holding time of 30 minutes to remove lithium stearate by evaporation. As a result of measuring the density of this preform, the theoretical density ratio was 77%. Next, after applying graphite powder as a lubricant on the surface of the preformed body and drying, heating in an argon gas atmosphere for 2 minutes and raising the temperature to 750 ° C., the die 2 shown in FIG. It was charged into a molding space 7a of a molding die 7 having an inner diameter of 30 mm. In this case, the molding die 7 is preheated to 750 ° C. in advance, and the core punch 3 and the sleeve punch 4 are simultaneously reduced in an argon gas atmosphere so as to be uniformly pressurized and compressed with the opposing punch 6, The powder was compacted uniformly at a pressure of 1 ton / cm ² to obtain a green compact 9. In the manufacturing process, it is not necessary to take out from the molding die 7, but for reference, the compacting material 9 was taken out from the molding die 7 in this state, cooled, and the dimensions and density were measured. Height 18.5m
m, theoretical density ratio was 99.6%. Next, after obtaining the green compact 9 which has been uniformly compressed by the same molding process as above, the press by the sleeve punch 4 is stopped and only the core punch having a diameter of 24 mm is lowered as shown in FIG. 1 (c). An anisotropic rare earth magnet material which is a sleeve-shaped molded product which is pressurized and compressed between the lever punch 3 and the opposing punch 6 and is rearward extruded between the inner peripheral surface of the die 2 and the outer peripheral surface of the core punch 3. I got 10. Pressure applied by Koapanchi 3 in this case is set to 4.0ton / cm ^2, the position of the end face 10b of the anisotropic rare earth magnet material 10 is still molded article the sleeve punch 4 applying pressure of pressure 0.6ton / cm ² I tried to keep up with the changes. After cooling this anisotropic rare earth magnet material 10, it was taken out of the argon atmosphere chamber and the dimensions were measured.
It had an inner diameter of 24.1 mm, a height of 45 mm, and a bottom thickness of 3.5 mm, and had no forming cracks on its inner and outer surfaces. Next, the bottom of this sleeve-shaped anisotropic rare earth magnet material 10
After cutting and removing 10a, this was magnetized in the radial direction to form an anisotropic rare earth magnet, and the maximum magnetic energy in the radial direction was measured. Was completed. Example 2 The same flake powder as above was weighed, and 100 g of the powder was weighed and heated as it was in a molding space 7a of a molding die 7 shown in FIG. 1 which was preheated to 800 ° C. in an argon atmosphere. Charged without. The inner diameter of the die 2 of this mold 7 is
It was 300 mm. Next, as shown in FIG. 1 (b), the core punch 3 and the sleeve punch 4 are simultaneously pressed down and held for ² minutes while being pressed with the opposing punch 6 at a pressing pressure of 1 ton / cm ² , and the forming die 7 is pressed. At the same time, the powder was heated by the heat transfer from the powder and the density was improved. Next, only the core punch (diameter 24 mm) 3 was pressed down and extruded backward to obtain an anisotropic rare earth magnet material 10 as a sleeve-shaped molded product. In this case, the pressure of the core punch 3 was 3.5 ton / cm ² , and the sleeve punch 4 was retracted so that no pressing force was applied. Next, after cooling the anisotropic rare earth magnet material 10,
Take out from the argon atmosphere chamber and measure the dimensions.
It was 30.1 mm, inner diameter 24.1 mm, height 45.5 mm, and bottom thickness 3.4 mm. However, a forming crack having a depth of about 1.2 mm occurred on the inner surface. Next, after cutting and removing the bottom portion 10a of the anisotropic rare earth magnet material 10 which is a sleeve-shaped molded product, the formed inner diameter portion is ground to remove a formed crack, and the inner diameter 2 is removed.
6.5 mm. This was magnetized in the radial direction to form an anisotropic rare earth permanent magnet, and the maximum magnetic energy in the radial direction was measured. As a result, an excellent magnetic property of 28 MG.Oe was obtained.

【The invention's effect】

In the method of manufacturing an anisotropic rare earth magnet according to the present invention, a die having openings at both ends, a sleeve punch having an opening on one side of the die and an outer peripheral surface slidable along an inner peripheral surface of the die, and A double-acting punch having a core punch slidable on the outer peripheral surface along the inner peripheral surface of the sleeve punch, and facing the double-acting punch and along the inner peripheral surface of the die at an opening on the other side of the die. A base metal alloy of a rare earth magnet using a forming die including a facing punch slidable on an outer peripheral surface, and a forming space formed between a facing double punch and a double acting punch having the die, the sleeve punch, and the core punch; Into a ribbon by ultra-rapidly cooling the preformed body obtained by cold compacting the powder obtained by pulverizing the ribbon to form a double-acting punch in a state where it is preheated to 650 to 900 ° C. in the molding space. Sleeve punch and core pan After uniformly pressing and compressing the preformed body until the density of the preformed body becomes 99% or more of the theoretical density between the and the opposing punch, the pressing by the sleeve punch of the double acting punch is stopped. Then, an anisotropic rare earth magnet having an annular cross section is manufactured by one heat heating by pressing and compressing between the core punch and the opposing punch and extruding between the inner peripheral surface of the die and the outer peripheral surface of the core punch. In the above manufacturing method, instead of using a pre-compacted body that has been cold-compacted, a sleeve that constitutes a double-acting punch with the raw material powder preheated to 650 to 900 ° C. in a molding space. The punch and the core punch and the opposing punch are uniformly pressurized and compressed. Further, in the above-described manufacturing method, instead of stopping the pressurization by the sleeve punch, the pressurization by the sleeve punch is performed. With the pressing force lower than the compressive force applied to the end face of the work material, press and compress between the core punch and the opposing punch, and extrude between the inner peripheral surface of the die and the outer peripheral surface of the core punch. Further, in the above-mentioned production method, the pressure compression and extrusion molding are performed under a vacuum or an inert gas atmosphere at a pressure lower than 1 Torr. In forming into a preformed body, a preform having an improved green density by mixing a lubricant such as lithium stearate in an amount of 2% by weight or less in order to improve the lubricating ability between the molding die and the powder particles. Because it was made into a molded body, it does not require molding in a magnetic field, and anisotropic ultra-quenched permanent magnets that magnetize after performing anisotropy by plastic deformation, When it is formed into a sleeve or ring-shaped annular cross section, it can be made into an anisotropic permanent magnet with high magnetic properties by one heat heating, and it can be heated and compressed to a theoretical density ratio of 99% or more. Pressure and pressure, and extrusion molding to form a sleeve or a ring are performed in the same mold, so that it is possible to significantly reduce the cost of the mold. A remarkably excellent effect that cracks on the inner surface can be prevented can be prevented. Then, as in the prior art, press compression and plastic working at a theoretical density ratio of 99% or more are performed in separate molds, and
As in the case of heating, there is provided a remarkably excellent effect that there is no decrease in magnetic properties due to coarsening of crystal grains by heating for a long time.

[Brief description of the drawings]

1 (a), 1 (b) and 1 (c) are cross-sectional views showing a method of manufacturing an anisotropic rare earth magnet according to an embodiment of the present invention in the order of steps, and FIGS. 2 (a) and 2 (b) are drawings of the present invention. FIGS. 3 (a), 3 (b), and 3 (c) are cross-sectional views showing a method of manufacturing an anisotropic rare earth magnet according to another embodiment in the order of steps. 4 (a) and 4 (b) are cross-sectional explanatory views showing a manufacturing method in the order of steps.
(C) is sectional explanatory drawing which shows the manufacturing method of the conventional anisotropic rare earth magnet in order of a process. 1 ... preformed body, 2 ... die, 3 ... core punch, 4 ... sleeve punch, 5 ... double acting punch, 6 ... opposed punch, 7 ... molding die, 7a ... molding space, 9 ... … Mold compaction material, 10 …… Anisotropic rare earth magnet material.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroshi Yoshida18, Minamikamochi, Kagiyacho, Tokai City, Aichi Prefecture (72) Inventor, Toshiya Kinami18, Minamikamochi, Kagiyacho, Tokai City, Aichi Prefecture18 (58) Fields surveyed (Int.Cl. ⁶ , DB name) H01F 41/02 B22F 3/03 B30B 11/22

Claims (5)

(57) [Claims] 1. A die having openings at both ends, a sleeve punch having an outer peripheral surface slidable along an inner peripheral surface of the die at one opening of the die, and an inner peripheral surface of the sleeve punch. A double-acting punch having a core punch whose outer peripheral surface is slidable, and a counter-acting member which is opposed to the double-acting punch and whose outer peripheral surface is slidable along an inner peripheral surface of the die at an opening on the other side of the die. Equipped with a punch, using a molding die in which a molding space is formed between a double-acting punch having the die, a sleeve punch, and a core punch and an opposing punch, ultra-quenching the base metal alloy of the rare-earth magnet into a thin ribbon, A pre-compacted body obtained by cold compacting the powder obtained by pulverizing the ribbon is formed in the molding space.
The pre-formed body is preheated to 650 to 900 ° C., and the pre-formed body is formed between the sleeve punch and the core punch constituting the double-acting punch and the opposing punch until the density of the pre-formed body becomes 99% or more of the theoretical density. After uniformly pressing and compressing, the pressing by the sleeve punch of the double-acting punch is stopped to press and compress between the core punch and the opposing punch, and at the same time, between the inner peripheral surface of the die and the outer peripheral surface of the core punch. A method for producing an anisotropic rare-earth magnet, comprising producing an anisotropic rare-earth magnet having a circular cross section by one heat heating by extrusion molding. 2. The method according to claim 1, wherein
Instead of using a pre-compacted body formed by cold compaction, the raw material powder is preheated to 650 to 900 ° C. in the molding space to form a double-acting punch. A method for producing an anisotropic rare earth magnet, comprising uniformly compressing and compressing. 3. The method according to claim 1, wherein the pressing force by the sleeve punch is lower than the pressing force, instead of stopping the pressing by the sleeve punch. Manufacture of anisotropic rare-earth magnets characterized by applying pressure to a core punch and an opposing punch in a state applied to an end face of a material and extruding between an inner peripheral surface of a die and an outer peripheral surface of a core punch. Method. 4. The method according to claim 1, wherein the compression and the extrusion are carried out under a vacuum or an inert gas atmosphere at a pressure lower than 1 Torr. A method for producing an anisotropic rare earth magnet. 5. The method according to claim 1, wherein the material powder is cold-compacted into a preform to form a molding die. Anisotropic rare earth characterized in that a green compact such as lithium stearate is mixed in an amount of 2% by weight or less in order to improve the lubricating ability between powder grains, and the green compact density is improved. Manufacturing method of magnet.