JPS6210258A - Manufacture of manganess-aluminum-carbon alloy magnet - Google Patents

Abstract

PURPOSE:To obtain an anisotropic magnet having high magnetic characteristics by producing a tensile strain in a hollow billet of an Mn-Al-C alloy in the extrusion direction by specified extrusion and by compressing the resulting billet having a prismatic hollow in the axial direction to make the inner surface circular. CONSTITUTION:The cavity in the container part 6 of dies consisting of a mandrel 2 and a die 3 has a hollow cross-sectional shape, and the area of the opening of the container part 6 (the area of the cross-section perpendicular to the extrusion direction) is larger than the area of the opening of the bearing part 7. A billet 1' is put in the container part 6, and after the axial direction is made parallel to the extrusion direction, the billet 1' is pressurized at 530-830 deg.C with a punch 4. A new billet 1 is then put in the container part 6 and pressurized in the same way, and extrusion is carried out by repeating the stages to obtain a billet 1 having a prismatic hollow with (2n+2) angles (n=1, 2, 3-). The billet 1 is compressed in the axial direction with the upper part 4 of a punch for preventing the billet 1 from expanding to the central part and an outer die 9 for restraining the outer surface of the billet 1 to make the inner surface of the billet 1 circular.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for manufacturing permanent magnets, and in particular to a method for producing permanent magnets, particularly Mn-Al-C for multipolar magnetization using polycrystalline manganese-aluminum-carbon (Mn-Al-C) based alloy magnets. The present invention relates to a method for manufacturing a 1-C alloy magnet.

BACKGROUND ART Mn-1-C based magnet alloy is a general term for Mn-1-C based magnet alloys and Mn-Al-C based alloy magnets. The Mn-Human 1-C magnet alloy contains 68 to 73% by weight (
Mn (hereinafter simply expressed as a cloud) and (1/10Mn-6,6
) ~ (1/3Mn-22,2)% C and the balance, ternary system containing no additive elements other than impurities, and multi-component alloy for magnets containing quaternary or higher elements containing small amounts of additive elements. are known, and these are collectively called. Similarly, Mn
-11-C alloy magnets are mainly composed of a face-centered tetragonal (τ phase, LIo type regular lattice) structure, which is a ferromagnetic phase, and contain C as an essential constituent element, and do not contain any additional elements other than impurities. Multi-component alloy magnets of ternary system and quaternary system or higher containing a small amount of additive elements are known, and these are collectively referred to as magnets.

In addition to casting and heat treatment, manufacturing methods include warm plastic working processes such as warm extrusion, and the latter method is especially effective because it has high magnetic properties, mechanical strength, weather resistance, machinability, etc. It is known as a method for manufacturing anisotropic magnets with excellent properties.

In addition, methods for producing multipolar magnetized alloy magnets using Mn-Al-C alloy magnets include isotropic magnets, compression processing, and uniaxial magnets obtained in advance by known methods such as warm extrusion processing. An anisotropic polycrystalline Mn-C alloy magnet is subjected to warm free compression processing in the anisotropic direction (for example, JP-A No. 5
6-119762), various plastic working methods that apply compressive strain in the axial direction of a hollow billet made of Mn-1-C magnetic alloy (for example, JP-A No. 58-1
No. 82206, Japanese Unexamined Patent Publication No. 182207/1982,
JP-A-58-182208), and Mn-mul-
A method in which a hollow body-shaped billet made of a C-based magnetic alloy and a billet made of a metal material are simultaneously compressed (for example, JP-A-60-59720, JP-A-60-59721)
(Japanese Patent Application Laid-open No. 60-69722) are known.

Problems to be Solved by the Invention Multi-pole magnets are generally cylindrical in shape, and the main magnetization is as shown in FIG. 4.

FIG. 4 schematically shows the formation of a magnetic path inside the magnet when the inner peripheral surface of the cylindrical magnet is magnetized with multiple poles, and such magnetization is herein referred to as inner peripheral magnetization.

In magnets obtained by various types of plastic working that apply compressive strain in the axial direction of the hollow billet made of the above-mentioned Mn-1-C magnetic alloy, when the above-mentioned inner periphery magnetization is applied, localized Although it is anisotropic in the direction along the magnetic path, when looking at the whole, it is not anisotropic in the desired direction. Furthermore, according to the above-mentioned known method, it is possible to obtain a cylindrical magnet whose inner periphery is anisotropic in the radial direction, and its outer periphery is anisotropic in the circumferential direction (chord direction, the same applies hereinafter). However, in the middle of the magnetic path changing from the radial direction to the circumferential direction, the anisotropic structure along that direction is not achieved, and it is necessary to perform plastic working at higher temperatures two or more times.

The present invention provides an anisotropic magnet with high magnetic properties.

Means for Solving the Problems In order to solve the above-mentioned conventional problems, the present invention provides
A billet in the form of a hollow body made of an n-person 1-C magnetic alloy is made using a die in which the cross-sectional shape of the hollow part of the container part is hollow and the opening area of the container part is larger than the opening area of the bearing part. Extrusion processing is performed with the axial direction of the billet parallel to the extrusion direction, and after applying tensile strain in the extrusion direction of the billet by the extrusion processing, the (2n+2) prismatic column (n = 1.2, 3,・
The inner circumferential surface of the billet is molded into a circular circumferential surface by compressing the billet in the axial direction of a hollow body-like billet having a hollow portion of the form (...).

Effect: By the method described above, that is, after the above-mentioned specific extrusion process, a (2n+2) prismatic column (n=1.2,3, . . .
) The inner peripheral surface of the billet is formed into a circular surface by compressing it in the axial direction. In this case, anisotropy can be achieved along the magnetic path, and an anisotropic magnet exhibiting high magnetic properties can be obtained.

Embodiment The present invention provides a hollow billet made of a Mn-1-1 magnetic alloy at a temperature of 530 to 830°C, with a hollow cross-sectional shape of a container portion being hollow, and an opening area of the container portion being Extrusion processing is performed using a die with a diameter larger than the opening area of the bearing part, with the axial direction of the billet parallel to the extrusion direction, and after applying tensile strain in the extrusion direction of the billet by the extrusion processing, the extrusion process is further performed. (2n+2) square column after processing (n=1.2.3+...
The inner circumferential surface of the billet is formed into a circumferential surface by compressing the billet in the axial direction of a hollow body having a )-shaped hollow portion.

The above-mentioned two plastic workings do not necessarily have to be continuous plastic working, and may be divided into multiple times.

An example of the extrusion process of the present invention will be described below with reference to FIG. 1, assuming that the shape of the billet is a cylindrical body shape.

FIG. 1a shows a cross section of a portion of the die before extrusion, and similarly FIG. 1a shows the die after extrusion. 1 is a cylindrical billet, 2 is a mandrel, 3 is a die, and 4 and 5 are punches.

The mandrel 2 and the die 3 constitute a die. In FIG. 1, reference numeral 6 denotes a container section that accommodates the billet 1 before extrusion processing.

Reference numeral 7 denotes a bearing section, which accommodates the billet 1 after extrusion processing. 8 is a conical part. Further, the opening area of the container part 6 is the cross-sectional area of the cavity of the container part 6 (perpendicular to the extrusion direction), which is approximately the same as the cross-sectional area of the billet 1 in FIG. 1, and the opening area of the bearing part 7 is , is the cross-sectional area of the cavity of the bearing part 7 (perpendicular to the extrusion direction), and almost coincides with the cross-sectional area of the billet 1 in FIG.

In FIG. 1, since both the container part 6 and the bearing part 7 are circular with the extrusion axis as the center, in other words, the opening area of the container part 6 is defined by the ring shape formed by the outer diameter and inner diameter of the container part 6. is the area of The cross-sectional shape of the hollow portion of the container portion 6 is the aforementioned ring shape and is hollow. Similarly, the opening area of the bearing part 7 is a ring-shaped area defined by the outer diameter and inner diameter of the bearing part 7. For example, the outer diameter of the container part 6 is 40 mm and the inner diameter is 20 ax, and the outer diameter of the bearing part 7 is 50 tm and the inner diameter is 40 mm.
tm, the opening area of the container section 6 is approximately 942 g.
j.

The opening area of the bearing portion 7 is approximately 707-.

In addition, the cross-sectional shape of the hollow portion of the container portion 6 has an outer diameter of 4
It is ring-shaped with a diameter of 0 m and an inner diameter of 20H.

In other words, the hollow cross-sectional shape of the hollow portion of the container section 6 is hollow when cut perpendicularly to the extrusion direction with the billet 1 housed in the container section 6, as shown in FIG. There is a die component (mandrel 2) on the outside, billet 1 is on the outside of the billet 1, and a die component (die 3) is on the outside.

An example of the extrusion processing method will be explained using FIG. 2.

First, as shown in FIG. 2, a cylindrical billet 1' is housed in a container portion θ. By pressurizing the billet 11 using the punch 4, it becomes as shown in FIG. Then the second
As shown in FIG. C, the billet 1 is newly placed in the container section 6, and the billet 1 is pressurized using the punch 4 in the same manner as described above, resulting in the state shown in FIG. 2D. Thereafter, extrusion processing is performed by repeating this process.

As another extrusion processing method, in the state shown in Fig. 2C,
While pressurizing the billet 1 with punches 4 and 6, the billet 1 is moved in the direction from the container part 6 to the bearing part 7 (in Fig. 2, the state of the billet 1 changes from Fig. 2 C to Fig. 2 D). ) and extrusion processing.

In FIG. 2a, the shape of the cylindrical billet 1' is made to have an appropriate clearance in order to facilitate insertion of the cylindrical billet 1' into the container part 6. The cross-sectional shape of the hollow portion of the container portion 6 (the shape of the hollow portion when the die is cut along a plane perpendicular to the extrusion direction) are both ring-shaped.

In the explanation of the extrusion process mentioned above, the shape of the billet was assumed to be cylindrical, but when considering the compression process in the next step, the shape of the billet is actually more like a (2n+2) prism (2n+2) than a cylinder.
n:=1. ．． A hollow body having a hollow portion in the shape of 2+31...) is better.

Next, as an example of compression processing, the billet shape is such that the cross-sectional shape of the outer peripheral surface is circular and the cross-sectional shape of the inner peripheral surface is square (that is, n
= 1) will be described using FIG. 3 as a hollow body shape. Figure 3a shows a cross section of the billet before compression processing when viewed from the axial direction.
A hollow billet with a square cross-sectional shape on its inner circumferential surface,
4 is the tip of the punch, which is a stepped part that prevents the billet 1 from spreading toward the center when the billet 1 is compressed and formed, and 9 is an outer mold that restrains the outer peripheral surface of the billet 1 during the compression process. This is a mold for. FIG. 3 is a sectional view taken in a direction perpendicular to FIG. 1.

4 and 5 are punches, which can be moved in the vertical direction in FIG. As shown in the figure, the tip of the punch 4 has a stepped portion with a reduced diameter, and the punch 5 has a hole into which the tip of the punch 4 fits. The tip of the punch 4 can shape the inner peripheral surface of the billet 1 into a circular shape. Therefore, in the example shown in FIG. 3, the shape of the billet 1 after compression processing becomes a substantially cylindrical body. It is not necessary to carry out the compression process until the inner circumferential surface of the billet 1 becomes a substantially perfect circumferential surface, and may be finished when the inner circumferential surface becomes almost a circular circumferential surface. Furthermore, in the example shown in FIG. 3, the outer peripheral surface of the billet 1 is already in contact with the inner surface of the outer mold 9 and is in a restrained state even before compression processing, but the outer diameter of the billet 1 is small and the outer peripheral surface of the billet 1 is in contact with the outer mold 9. It doesn't have to be. In this case, as the compression process progresses, the outer diameter of the billet 1 increases, and eventually becomes the same state as shown in FIG. 3.

In this case, the minimum size of the hollow portion (cavity) of the billet 1 before compression processing can be made small enough to contact the tip of the punch 4. In this case, a part of the inner peripheral surface of the billet 1 is already in contact with the tip of the punch 4 before the compression process, and the compression process is performed in a restrained state.

In the above example, the shape of the inner circumferential surface of the billet changes from square to approximately circular due to the compression process. Such changes result in an anisotropic structure suitable for inner circumferential magnetization. In the compression processing process, the part where the inner peripheral surface is restrained earliest (the central part of one plane of the inner peripheral surface of the billet before processing, and the part closest to the tip of the punch 4) has an easy magnetization direction in the circumferential direction. The part where the inner peripheral surface is finally restrained or the part where the inner peripheral surface is not restrained until the end (the part corresponding to the corner of the inner peripheral surface of the billet before processing) is a part with an easy magnetization direction in the radial direction. Become. The easy magnetization direction of the intermediate portion changes sequentially from the circumferential direction to the radial direction. In this manner, the shape of the hollow portion of the billet 1 before compression processing may be determined depending on whether or not the inner periphery is magnetized with the same polarity. That is, in the example described above, the shape of the inner circumferential surface of the billet 1 was square, so it has an anisotropic structure suitable for quadrupole magnetization. The reason why the shape of the hollow part is (2n, + 2) prismatic is because, as mentioned above, the shape of the hollow part of the billet must be an even polygonal shape, and n =
When n=1, it is for 4 poles, when n=2, it is for 6 poles, etc. The smaller n is, the clearer the anisotropic structure according to the position described above is, but as n becomes larger, it becomes less clear.

(2n+2) prismatic column (n=1.2+3+...
...)-shaped hollow part is a geometrically accurate (
2n+2) It does not have to be a square shape, and there is no problem even if there is some chamfering.

As described in the above example, the present invention is a (2n+2) prism (n=1r 2 +3,...) after the above specific extrusion process.
When compressing a hollow body-shaped billet having a hollow part in the axial direction, the inner peripheral surface of the billet is molded into a circular shape using a mold, etc. When the inner periphery magnetization shown in the figure is applied, anisotropy can be achieved along the magnetic path, and an anisotropic magnet exhibiting high magnetic properties can be obtained.

Regarding the possible temperature range of plastic working as mentioned above,
Processing was possible in the temperature range of 530 to 830'C, but the magnetic properties deteriorated significantly at temperatures exceeding 780'C. The most desirable temperature range was 560 to 760°C.

Next, a more specific example of the present invention will be described.

Example 1 Blend composition: 69.5% Mn, 29.3% Al
.

Melting and casting 0.5% C and 0.7% N1, the outer circumferential surface is circular with an outer diameter of 26 mm, and the inner circumferential surface is square with a side length of 5 mm.
A hollow billet with a length of 2 oH and a length of 2 oH was prepared. After holding this billet at 1100'C for 2 hours,
After air-cooling to 00°C, holding at 600°C for 30 minutes, heat treatment was performed by cooling to room temperature. Then, through lubricant,
Extrusion processing as shown in FIG. 1 was carried out at a temperature of 720°C. However, the inner surface of the die 3 is circular, and the shape (cross-sectional shape) of the mandrel 2 is square. The diameter of the outer circumferential surface of the container part (the inner diameter of the die 3, the same below) is 26 mm, the length of one side of the inner circumferential surface is 20 mm, the same below) is 6 fi, and the diameter of the outer circumferential surface of the bearing part is 3 Q. , the length of one side of the inner peripheral surface is 18+n+, and X is 20 pieces. The extruded billet has an outer circumferential diameter of 30 ttg, an inner circumferential surface with a side length of 18 mm, and a hollow body having a length of 26-5 m. The processed billet was cut to a length of 20 tm.

This billet was compressed at a temperature of 680° C. using a mold shown in FIG. 3 through a lubricant. The inner diameter of the outer mold 9 is 30 mm, and the diameter of the tip of the punch 4 is 18 mm and is circular. Using such a mold, height 13,
Compression processing was performed up to 8H.

The billet after compression processing has an inner diameter of 15. Cut to 4
The inner circumference of the pole was magnetized. Magnetization was performed using a 2000 μF oil capacitor and pulsed magnetization at 15 oV. The surface magnetic flux density on the inner peripheral surface was measured using a Hall element.

For comparison, Mn with the same blending composition as described above
, Ml, C and Ni were melted and cast, diameter 60U, length 4
0. A cylindrical billet was prepared. This billet is 110
After being held at 0''C for 2 hours, it was heat treated to cool to room temperature.Next, it was subjected to a known extrusion process to a diameter of 31 tm at a temperature of 720'C via a lubricant.This extrusion The rod was cut to a length of 20 ts and machined to produce a cylindrical billet with a diameter of 22mm and a length of 20wx.The billet was heated at a temperature of 880'C to a length of 13mm in the axial direction of the cylinder.
Free compression processing was performed up to the bus. The processed billet (planar anisotropic magnet) was cut and magnetized in the same manner as described above, and the surface magnetic flux density was measured.

Comparing the surface magnetic flux density values of both of the above, the value of the magnet obtained by the method of the present invention was about 1.7 times that of the magnet produced for comparison.

Example 2 Blend composition: e 9.4% Mn, 29.3'% Mn
0.6 inch a, O.7 inch Ni and 0.1 inch T1 are melted and cast, the outer circumferential surface is circular with an outer diameter of 40 mm, the inner circumferential surface is square with a side length of 22 N, and a length of 0.6 mm. A hollow body-shaped billet with a diameter of 20+w was produced. After holding this billet at 1100°C for 2 hours, it was air-cooled to 600°C, and then heated to 600"C for 30
After holding for a minute, a heat treatment was performed in which the sample was allowed to cool to room temperature. Next, extrusion processing as shown in FIG. 1 was carried out at a temperature of 72° C. using a lubricant. However, the inner surface of the die 3 is circular, and the shape (cross-sectional shape) of the mandrel 2 is square. The diameter of the outer peripheral surface of the container part of the die is 40 fl, the length of one side of the inner peripheral surface is 22 m, the diameter of the outer peripheral surface of the bearing part is 30 mx, the length of one side of the inner peripheral surface is 18 fl,
is 20tm. After extrusion, the billet has an outer peripheral diameter of 30 mm, an inner peripheral surface with a side length of 18 mm, and a length of 4 mm.
It has a hollow body shape with 0.4 hollow parts.

The processed billet was cut to a length of 20 mm.

This billet was compressed using a mold shown in FIG. 3 at a temperature of 68° C. through a lubricant. The inner diameter of the outer mold 9 is 30 m, and the diameter of the tip of the punch 4 is 18 m.
It is m+ and is circular. Using such a mold, height 1
Compression processing was performed up to 3.8 m.

After compression processing, the billet is cut to an inner diameter of 15 fl,
Four-pole inner circumferential magnetization was applied. For magnetization, a 2000 μF oil capacitor was used, and pulse magnetization was performed at 1500 V. The surface magnetic flux density on the inner peripheral surface was measured using a Hall element.

For comparison, Mn with the same blending composition as described above
, person 1. Melting and casting C, Ni and Ti, diameter 50 m
A cylindrical billet with a length of 40 ts was prepared.

After holding this billet at 1000° C. for 2 hours, it was heat-treated by being allowed to cool to room temperature. Next, through the lubricant, 72
A known extrusion process was carried out at a temperature of 0° C. up to 24 pieces in diameter. This extruded rod was cut into lengths of 20 pieces and machined to produce cylindrical billets with a diameter of 22 pieces and a length of 20 pieces.

This billet was heated to a temperature of 680°C to a length of 1 in the axial direction of the cylinder.
Free compression processing was performed to a length of 3-8 m. The processed billet (planar anisotropic magnet) was cut and magnetized in the same manner as described above, and the surface magnetic flux density was measured.

Comparing the values of the surface magnetic flux density of both of the above, the value of the magnet obtained by the method of the present invention was about 1.7 times that of the magnet produced for comparison.

Example 3 Mn, MuL, C and N1 having the same composition as in Example 1 were melted and cast to produce a cylindrical billet with a diameter of 600 mm and a length of 30 mr. This billet was held at 1100''C for 2 hours, and then heat-treated by allowing it to cool to room temperature.

Then, through lubricant, at a temperature of 720″C, a diameter of 31m
A known extrusion process was performed. The extruded rod was cut into lengths of 20 mm and machined to form a circular outer circumferential surface with an outer diameter of 26 fl.
A hollow billet (billet Also,
The extruded rod was cut to a length of 35 m and machined to a diameter of 30 m.
try, cylindrical billet with length 36 tx (billet Y
). Using this billet Y, through a lubricant,
The billet was subjected to free compression in the axial direction at a temperature of 680°C. The length of the billet after processing was 20 m. After this processing, the billet (planar anisotropic magnet) is cut and machined in the same manner as billet x, and the outer peripheral surface is circular and the outer diameter is 2.
66, the inner surface is square, the length of each side is 5, and the length is 20 t.
A hollow billet (billet Y) of m was prepared. Next, the same extrusion processing and compression processing as in Example 1 were performed. That is, extrusion processing as shown in FIG. 1 was carried out at a temperature of 720° C. using Pillet) However, the inner surface of the die 3 is circular, and the shape (cross-sectional shape) of the mandrel 2 is square. The diameter of the outer peripheral surface of the container part of the die is 26 fl, and the length of one side of the inner peripheral surface is 51 II.
I, and the diameter of the outer peripheral surface of the bearing part is 30 m.

The length of one side of the inner peripheral surface is 18 m, and X is 20 y. The billet after extrusion has a diameter of 30 mm on the outer circumferential surface, a length of 1'8 tx on one side of the inner circumferential surface, and is in the form of a hollow body having a hollow portion of 26.6 mm in length. The processed billet was cut to a length of 20 tm. Using the mold shown in Fig. 3, these billets were heated to 680 mm using a lubricant.
Compression processing was performed at a temperature of 'C. The inner diameter of the outer mold 9 is 30
ym, and the diameter of the tip of the punch 4 is 18 mm, which is circular. Compression processing was performed to a height of 13-8 m using such a mold.

The billet after compression processing is cut to an inner diameter of 15 m, and
The inner circumference of the pole was magnetized. For magnetization, a 2000 μF oil capacitor was used, and pulse magnetization was performed at 15 oov. The surface magnetic flux density of the inner peripheral surface was measured with a Hall element, and compared with the value of the surface magnetic flux density of the magnet produced for comparison in Example 1.

Comparing the above values of surface magnetic flux density, the value of the magnet obtained in Example 3 shows almost no difference between billet x and billet Y, and is about 1. It was 8 times more.

The magnets obtained by the method of the present invention obtained in Examples 1, 2, and 3 were 1. As a result of magnetic torque measurement, as mentioned above, the direction of easy magnetization was in the radial direction at the corner portion of the inner circumference of the billet before compression processing. , along the circumferential direction in the middle part, and between them, it was found that there is a continuous change from the radial direction to the circumferential direction.

As mentioned above, regarding the composition of the Mn-Ml-C magnet alloy, N
Although only the four-element system with i addition and the six-element system with Ni and Ti additions are shown, it is possible to use the ternary system which is the basic composition of Mn-1-C alloy magnets or the known ones containing additive elements other than those mentioned above. Although some differences were observed in the magnetic properties of the magnets after plastic working for the multi-component system, the above-mentioned improvement in magnetic properties was observed compared to the conventional method.

Effects of the Invention As is clear from the above explanation, the present invention has the advantage that Mn-Al-
A hollow billet made of C-based magnetic alloy is extruded in the axial direction of the billet using a die in which the cross-sectional shape of the hollow part of the container part is hollow and the opening area of the container part is larger than the opening area of the bearing part. Extrusion processing is performed with the directions parallel to each other, and tensile strain is applied to the billet in the extrusion direction by the extrusion processing, and then (2n+2) prismatic columns (n=1.2, 3, . . . ) after the extrusion processing are performed. ...
・High magnetic properties can be achieved when the inner circumferential surface of the billet is formed into a circumferential surface by compression processing in the axial direction of a hollow body-shaped billet having a )-shaped hollow part, and magnetization is performed on the inner circumference. Comparing the magnet produced by the method of the present invention with the magnet produced by the conventional method, the magnet produced by the method of the present invention shows superior magnetic properties than the magnet produced by the conventional method when the inner circumference is magnetized.
Furthermore, in order to obtain a structure in which the inner periphery of the magnet has an easy magnetization direction in the radial direction, and the outer periphery has an easy magnetization direction in the circumferential direction, conventional methods require plastic working at least twice. However, with the method of the present invention, only one step is required, and a magnet having a more desirable anisotropic structure can be obtained.

[Brief explanation of the drawing]

FIGS. 1a and 1b are cross-sectional views of a part of a mold showing an example of the extrusion process of the present invention, and FIGS. 2 a-d are cross-sectional views of a part of the mold showing an example of the extrusion method of the present invention, Figures 3a and b are a cross-sectional view and a vertical cross-sectional view, respectively, of a mold used in compression processing according to an embodiment of the present invention, and Figure 4 is a diagram showing a case where the inner peripheral surface of a cylindrical magnet is subjected to multipolar magnetization. FIG. 3 is a diagram schematically showing the formation of a magnetic path inside a magnet. 1.1'... Billet, 2... Mandrel, 3... Die, 4.5... Punch, 6... Container part , 7...bearing part, 9...outer mold. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 3
Figure 3

Claims (4)

[Claims] (1) A hollow billet made of manganese-aluminum-carbon magnet alloy is heated at a temperature of 530 to 830°C, and the cross-sectional shape of the hollow part of the container part is hollow, and the opening area of the container part is the same as that of the bearing part. Using a die larger than the opening area, extrusion processing is performed with the axial direction of the billet parallel to the extrusion direction, and tensile strain is applied to the billet in the extrusion direction by the extrusion processing, and then ( 2n+2) prismatic (n=1, 2, 3, ・
Manganese-aluminum-carbon, characterized in that the inner circumferential surface of the billet is formed into a circumferential surface by compressing the billet in the axial direction of a hollow body-like billet having a hollow portion in the form of... Manufacturing method for alloy magnets. (2) The method for manufacturing a manganese-aluminum-carbon alloy magnet according to claim 1, wherein the compression processing is performed with a portion of the outer circumferential surface of the billet being restrained. (3) A patent characterized in that the compression process is performed with at least a portion of the outer circumferential surface and inner circumferential surface of the billet free, and then further carried out with the outer circumferential surface of the billet constrained. A method for manufacturing a manganese-aluminum-carbon alloy magnet according to claim 1. (4) The method for manufacturing a manganese-aluminum-carbon alloy magnet according to claim 1, wherein the compression processing is performed with a portion of the inner circumferential surface of the billet being restrained.