JPH0434806B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method of manufacturing a permanent magnet. More specifically, the present invention relates to a method of manufacturing a polycrystalline manganese-aluminum-carbon (Mn-Al-C) alloy magnet, and particularly to a method of manufacturing a high-performance Mn-Al-C alloy magnet for multipolar magnetization.

Structure of conventional examples and their problems Mn-Al-C alloy magnets are mainly composed of a face-centered tetragonal (τ phase, _L10 type ready-made lattice) structure, which is a ferromagnetic phase, and C is an essential constituent element. There are known ternary alloy magnets that contain no additive elements other than impurities, and multi-element alloy magnets that include quaternary or higher alloy magnets that contain small amounts of additive elements, and these are collectively referred to as magnets.

Furthermore, as a manufacturing method for this Mn--Al--C alloy magnet, there are known methods that include a plastic working process such as extrusion in addition to casting and heat treatment.
In particular, the latter method is known as a method for producing anisotropic magnets having excellent properties such as high magnetic properties, mechanical strength, weather resistance, and machinability.

Manufacturing methods for Mn-Al-C alloy magnets for multipolar magnetization include isotropic magnets, compression processing, and uniaxially anisotropic polycrystalline Mn obtained in advance by known methods such as extrusion processing. -Al-C alloy magnets subjected to free compression processing in an anisotropic direction (composite processing method) are known.

Compression processing provides high magnetic properties in the radial direction, but a relatively large processing rate is required, non-uniform deformation may occur, and the presence of undeformed bands is unavoidable. There are problems such as: With the combined processing method, high magnetic properties are obtained in all directions within the plane, including the radial and chordal directions, with small compressive strain. The magnet obtained by the composite processing method has an easy magnetization direction parallel to a specific plane, is magnetically isotropic within the plane, and includes a line perpendicular to the plane and a straight line parallel to the plane. It has a structure that is anisotropic in a plane (hereinafter, such a magnet will be referred to as a plane anisotropic magnet).

On the other hand, the shape of a magnet used in the field of multipolar magnetization is generally an axially symmetrical shape, and an example is a cylindrical shape. FIG. 1 schematically shows the formation of a magnetic path inside the magnet when the outer periphery of a cylindrical magnet is magnetized with multiple poles. In Figure 1, the broken line indicates the magnetic path,
The chordal direction (θ direction) with respect to one radial direction (r direction) is also shown. The direction perpendicular to the radial direction (r direction) of the cylinder and the axial direction of the cylinder is defined as the chordal direction (θ direction).

As shown in FIG. 1, the magnetic path runs approximately in the radial direction at the outer periphery, along the chord direction at the inner portion, and no magnetic path runs through the inner portion. If the shape of the magnet is cylindrical, the magnet can be divided into three parts as mentioned above.
The first is the part where the magnetic path runs along the radial direction (part A),
The second is the part where the magnetic path is along the chord direction (part B),
The third part is a part (C part) through which no magnetic path passes.

The above-mentioned plane anisotropic magnet is a magnet that has an easy magnetization direction in any direction parallel to the plane including the radial direction and the chordal direction, so when it is magnetized on the outer periphery in this way, it has excellent magnetic properties. However, when it is divided into three parts as described above, each part does not have a desirable anisotropic structure. In other words, A
It is better to have higher magnetic properties in the radial direction than in the chordal direction in the B section, and it is better to have higher magnetic properties in the chordal direction than in the radial direction in the B section. On the other hand, a radially anisotropic magnet (or a magnet with a radial direction of easy magnetization)
When a magnet is shaped like a hollow body, it is a magnet whose direction of easy magnetization is parallel to a straight line passing through an arbitrary point on a plane perpendicular to the axial direction of the hollow body, and when it is a cylindrical body as shown in Fig. 1, the direction of easy magnetization is in the r direction. In a magnet (having an easy magnetization direction in the radial direction), part A has a desirable anisotropic structure, but part B has an undesirable anisotropic structure.

Purpose of the Invention The present invention provides an Mn-Al material suitable for high-performance multipole magnetization.
- It is an object of the present invention to provide a method for manufacturing a C-based alloy magnet.

Structure of the Invention The present invention provides polycrystalline Mn that has been anisotropically made in advance.
- With the billet made of a metal material present in the hollow part of the hollow billet made of an Al-C alloy magnet, the two parts are It is characterized by being compressed until the two billets touch or further until they are integrated.

Compressing a hollow billet made of a polycrystalline Mn-Al-C alloy magnet that has been made anisotropic in advance, with a billet made of a metal material present inside the billet, until the two billets come into contact with each other or further. By this, it is possible to obtain a Mn-Al-C alloy magnet having a radial direction of easy magnetization,
By compressing it together with a billet made of metal material, it can be used to make it easier to drill holes for shaft attachment when applied to magnet rotors, etc., or it can be compression molded together with the shaft. .

Furthermore, if the billet made of the metal material is a billet whose outer periphery is made of a magnetic material, it is possible to obtain a magnet having two structures suitable for the above-mentioned outer periphery magnetization.

After a hollow billet made of an Mn--Al--C alloy magnet is compressed, it becomes a magnet with a structure suitable for part A, and after compression, the magnetic body part becomes a structure suitable for part B. Moreover, since two or more billets are simultaneously compressed and brought into contact with each other, magnets having two or more types of structures can be obtained after the compression process.

Description of Examples Known Mn-Al-C alloys for magnets, e.g. 68~
73% by weight (hereinafter simply expressed as %) of Mn and (1/10・
Mn−6.6) to (1/3・Mn−22.2)% of C and the remainder
By subjecting an alloy made of Al to plastic working such as extrusion in a temperature range of 530 to 830°C, an anisotropic polycrystalline Mn-Al-C alloy magnet can be obtained. Typical examples of the magnet include a uniaxial anisotropic magnet having an easy magnetization direction in the extrusion direction obtained when the plastic working is performed by extrusion, the above-mentioned planar anisotropic magnet, and radial anisotropic magnet. and so on.

When a billet made of a metal material is present in the hollow part of the hollow body, for example, a cylindrical billet made of the anisotropic polycrystalline Mn-Al-C alloy magnet, the axis of the hollow billet is A Mn-Al-C alloy magnet having a radial direction of easy magnetization can be obtained by compressing the magnet until the two billets come into contact with each other or further, and compressing the magnet along with the billet made of metal material. Because it is processed, it is easy to drill holes for attaching a shaft when applied to a magnet rotor, etc., and the shaft can also be compression molded.

The above metal material is a Mn-Al-C alloy magnet.
Any material may be used as long as it can be compressed in the temperature range of 530 to 830°C. There is no need to be particular about metal materials in general. In other words, it may be a billet made of a certain material.

Furthermore, if the billet made of the metal material described above is a billet whose outer circumferential portion is made of a magnetic material, the outer circumferential portion of the billet after compression processing (the portion corresponding to the hollow billet before compression processing) will be radially The part has high magnetic properties, and the part inside the part (the part of the magnetic material) becomes a part suitable for the magnetic path to follow the chord direction when the outer periphery is magnetized. As a result, the three divided portions A and B are formed when the outer periphery magnetization described above is applied, and a magnet exhibiting excellent magnetic properties in the outer periphery magnetization is obtained.

The above-mentioned magnetic material may be any magnetic material as long as the chord direction does not become the difficult-to-magnetize direction after the above-described compression process. Here, the difficult magnetization direction means the direction in which magnetization is difficult in outer circumferential magnetization, such as the [111] direction of single crystal Fe.
= 500 Oe, if there is no significant difference in magnetization strength from the [100] direction of the easy axis of magnetization, it cannot be said that it is a difficult direction for magnetization in outer circumference magnetization. The above-mentioned magnetic material is Mn-Al with a planar anisotropic structure after compression processing.
- Alloys that can be made into C-based alloy magnets, broadly known as Mn-Al
-C-based magnet alloy (Mn-Al-C-based magnet alloy)
Mn-Al-C alloy magnet), isotropic Mn-
Examples include high magnetic permeability materials such as Al-C alloy magnets, pure iron, electromagnetic soft iron, and Fe-Co alloys.

When the hollow billet is made of a polycrystalline Mn-Al-C alloy magnet (uniaxially anisotropic magnet) having an easy magnetization direction in the axial direction of the hollow body, the above-mentioned compression process It is necessary to apply a compressive strain of 0.05 or more in the absolute value of logarithmic strain in the axial direction of the hollow billet. This is because, as detailed in the examples, the structure is anisotropic in the axial direction before compression processing, and a compression strain of at least 0.05 is required for the structure to exhibit high magnetic properties in the radial direction. It is.

When the hollow billet is made of a polycrystalline Mn-Al-C alloy magnet (planar anisotropic magnet) having an easy magnetization direction parallel to a plane perpendicular to the axial direction of the hollow body, compression Before processing, it already exhibits high magnetic properties in all directions within the plane including the radial direction and the chordal direction, but by applying the compression processing described above, the direction of easy magnetization changes to follow the radial direction.

A polycrystalline Mn-Al-C alloy magnet (radially anisotropic magnet) in which the hollow billet has an easy magnetization direction parallel to a straight line passing through an arbitrary point on a plane perpendicular to the axial direction of the hollow body In the case of a magnet having a radial direction of easy magnetization), it will show even higher magnetic properties in the radial direction by compression processing, and can be brought into contact with a billet made of a metal material existing in the hollow part. .

The compression process described above does not necessarily have to be continuous compression process, and may be divided into multiple times. Furthermore, the bit subjected to the above-mentioned compression processing may be further subjected to compression processing in the axial direction on a portion of the billet (for example, the outer peripheral portion).

As an example of the above-mentioned compression processing, a hollow billet (billet A) is made into a cylindrical shape, and a billet made of a metal material existing in the hollow part of the hollow body (billet B) is made into a cylindrical or cylindrical shape. Let me explain some examples. FIG. 2 shows six examples of states before compression processing. In Figure 2,
1 is anisotropic polycrystalline Mn-Al-C
The billet is a cylindrical billet (billet A) made of a series alloy magnet, and the billet 2 and 3 are made of a metal material (billet B). The billet 3 is made of two types of metal materials. For example, in b, 2 is a Mn-Al-C alloy magnet, 3 is a combination of brass, etc. 4 and 5 are punches, which can be moved freely in the axial direction and can also be fixed at a certain position.
6 is fixed by the outer mold.

First, in step a, billet A is compressed while its outer periphery is constrained, and billet B is freely compressed.
As the compression process progresses, the inner diameter of billet A becomes smaller and the diameter of billet B becomes larger, so that both billets come into contact with each other. Compression processing can be carried out until the empty space is almost completely eliminated and the billets A and B are almost filled. b is almost the same as a, except that billet B has three parts. c is a state in which billets A and B are already in contact before the compression process, but this is only a contact that can be easily separated, but by performing the compression process, the inner diameter of billet A becomes smaller (and If billet A is not available, billet B
deforms in the direction of increasing the outer diameter due to compression processing) resulting in stronger contact. At d, as the compression process progresses, the inner diameter of billet A becomes smaller and the outer diameter of billet B becomes larger, and eventually they come into contact. e is the same as c. Unlike the previous cases a to e, the outer periphery of the billet A is not in contact with the outer mold 6. In other words, the outer periphery of billet A is free and unrestricted. However, as the compression process progresses, the outer diameter of billet A increases, and eventually it comes into contact with the inner wall of outer mold 6, and from then on, the billet A becomes larger in diameter.
This is similar to (b) etc.

Note that FIGS. 3 and 4 schematically show the states before and after the compression processing shown in FIGS. 2a and d. In each figure, a shows the state before processing, and b shows the state after processing.

In FIG. 2, the outer periphery of billet A1 is restrained by the outer mold 6 at point a, but the inner periphery is free. In c, the outer periphery of billet A1 is restrained by the outer mold 6, as in a, and the inner periphery is in contact with the outer periphery of billet B2. However, since the inner circumference of billet B is free, billet A
Since the inner diameter of billet A can be reduced as the compression process progresses, the inner circumference of billet A can be considered to be in a free state. At f, the outer periphery of the billet A1 is not in contact with the outer mold 6, so it can be considered to be in a free state.

In the compression process shown in FIG. 2, the entire billet is compressed, but a method may also be used in which a region that is not compressed locally is created. For example, there is a method of preserving the structure before processing without locally compressing billet A. Specifically, for example, in Fig. 2c, if a step is provided on the punch 5 that matches the inner diameter of billet A, and the length of billet B is shortened by that amount, and a part of the inner circumference of billet A is restrained, the constraint will be The part that has been compressed (the part that is not compressed and deformed) preserves the structure before processing.

In the example of compression processing shown in Fig. 2, there is a region during the compression processing where at least the outer periphery of billet A is constrained, but it is not always necessary to constrain the outer periphery of billet A. It is not necessary to have a part that undergoes compression processing in the state. For example, in FIG. 2c or e, even if compression is performed without the outer mold 6, billets A and B can be brought into contact after compression. Further, if the compression process brings billets A and B into contact after the compression process, the billet A will have a structure having an easy magnetization direction in the radial direction after the compression process. but,
It is better to have a part where the compression process is performed while the outer periphery of billet A is constrained as described above, so that the bonding property (strength of contact) between the two billets is better.
can be made more strongly anisotropic in the radial direction by compression processing.

In addition, polycrystalline Mn-Al that has been made anisotropic in advance
- A billet made of a metal material existing in the hollow part of a hollow billet made of a C-based alloy magnet,
When occupying the entire area of the hollow portion, a plane anisotropic magnet can be obtained by compression processing. Even in this case, since the center part of the magnet is made of metal material, drilling becomes easier. For example, a specific example is a case where only parts 2 and 3 shown in FIG. 2b are compressed. Here, 2 is a cylindrical billet made of a polycrystalline Mn-Al-C alloy magnet which has been made anisotropic in advance, and 3 is a billet made of a metal material.

In the example shown in FIG. 2, the heights of billets A and B before compression are approximately equal. However, they do not necessarily have to be equal. For example, billet A may be higher. Furthermore, when the magnet obtained according to the present invention is used in a magnet rotor or the like, if a shaft needs to be attached, the shaft may be attached at the same time as the compression process. Furthermore, billet A
Alternatively, B does not need to consist of one thing, but may consist of two or three or more things. That is, for example, in FIG. 2a, the billet A is divided into three parts, and by combining the three parts, the billet A may be formed into a cylindrical shape.

If a substantially cylindrical sample is desired to be obtained even after compression processing, a mandrel or the like may be used to shape the inner peripheral surface. For example, in the case of FIG. 2c, if a mandrel or the like is used, a substantially clean cylindrical body can be obtained even after compression processing.

Since compression processing is performed in a temperature range of 530 to 830℃, billets A, B, and C are made of different materials, so when they are cooled to room temperature after processing, they will become a shrink fit due to the difference in thermal expansion coefficient. Otherwise, gaps may occur between the billets, so when using materials other than Mn-Al-C magnet alloys, Mn-Al
- It is necessary to consider the magnitude relationship with the coefficient of thermal expansion of the C-based magnet alloy.

In the example shown in FIG. 2, there is no other billet outside the hollow billet (billet A1), but a billet made of another metal may be present. For example, in Figure 2e,
In this case, 1 is a billet made of metal (for example, steel), 2 is a hollow billet made of an Mn--Al--C alloy magnet which has been made anisotropic in advance, and 3 is a billet made of a metal material.

Furthermore, if the billet (billet B2) made of the metal material described above is a billet made of a magnetic material at least at the outer circumferential portion, billet A becomes a magnet having a radial direction of easy magnetization after compression processing,
This is a part suitable for the part A in the outer circumferential magnetization described above. The magnetic material part becomes the part suitable for part B,
A magnet having two or more types of structures can be obtained. For example, in FIG. 2a, if billets A and B are both uniaxially anisotropic magnets having easy magnetization directions in the cylinder or cylinder axis direction, after compression processing, A becomes a radially anisotropic magnet, and B becomes the planar anisotropic magnet mentioned above.

Regarding the possible temperature range of compression processing as mentioned above, it was possible to perform it in the temperature range of 530 to 830℃, but
At temperatures above 780°C, the magnetic properties deteriorated considerably. A more desirable temperature range was 560 to 760°C.

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

Example 1 Melt and cast a mixture of 69.5% Mn, 29.3% Al, 0.5% C and 0.7% Ni, diameter 50 mm, length
A 40 mm cylindrical billet was made. This billet
After holding at 1100° C. for 2 hours, heat treatment was performed by allowing it to cool to room temperature. Next, it was extruded using a lubricant at a temperature of 720°C to a diameter of 30 mm. This extruded rod was cut to a length of 20 mm and machined to create a shape with an outer diameter of 30 mm and an inner diameter of 30 mm.
A cylindrical billet (billet A) with a diameter of 24 mm and a length of 20 mm was prepared.

Next, we cut and machined the brass bar material to create an outer diameter of 24 mm.
A cylindrical billet (billet B) with a diameter of 20 mm, an inner diameter of 20 mm, and a length of 20 mm was prepared.

Billet B is placed in the hollow part of billet A, and in the state shown in Fig. 2c, compression processing is performed at a temperature of 680°C using lubricant using a mold as shown in Fig. 2c. Ivy. In addition, in FIG. 2c, the inner diameter of the outer mold 6 is 30 mm. The height of the billet after processing is 10
It was warm in mm.

A cubic sample with a side of 4 mm was cut out from the outer periphery of the processed billet (corresponding to billet A before processing) with each side along the radial, chordal, and axial directions, and the magnetic properties were measured.

The magnetic properties are B _r = 5.9kG in the radial direction, Hc =
2.7kOe, (BH) _nax = 6.4MG・Oe, B _r in chord direction
=3.0kG, H _c =2.2KOe, (BH) _nax =1.8MG・Oe,
In the axial direction, B _r = 2.8kG, Hc = 2.1kOe, (BH) _nax
= 1.6MG・Oe. The magnet had an easy magnetization direction in the radial direction.

Furthermore, since the inner periphery of the processed billet was made of brass, it was easy to cut into a cylindrical shape, and it was also easy to achieve dimensional accuracy.

Example 2 Melt and cast a mixture of 69.5% Mn, 29.3% Al, 0.5% C and 0.7% Ni, diameter 70 mm, length
A 60 mm cylindrical billet was made. This billet
After holding at 1100° C. for 2 hours, heat treatment was performed by allowing it to cool to room temperature. Next, extrusion processing up to a diameter of 45 mm was performed at a temperature of 720°C via a lubricant. Furthermore, extrusion processing up to a diameter of 31 mm was performed at a temperature of 680°C using a lubricant. This extruded rod was cut to a length of 20 mm and machined to produce a cylindrical billet (billet A) having an outer diameter of 30 mm, an inner diameter of 15 to 24 mm, and a length of 20 mm.

Next, the 31 mm extruded rod was further extruded using a lubricant at a temperature of 680° C. to a diameter of 15 mm. This extruded rod was cut to a length of 20 mm and machined to produce several cylindrical billets (billet B) having an outer diameter of 11 to 13 mm and an inner diameter of 5 mm. A piece of brass (diameter 5 mm, length 20 mm) was inserted into the hollow part of billet B.

Using one billet A and one billet B, put billet B into the hollow part of billet A, and press it with lubricant in the same mold as in Example 1 and in the state shown in Figure 2b. Compression processing was performed at a temperature of 680°C with varying compressive strains. In addition, compression processing is performed using outer diameter 6, punches 4 and 5, and billets 1, 2, and 3.
The process continued until there was no space left.

A cubic sample was cut out from the outer periphery of the processed billet (corresponding to billet A before processing) in the same manner as in Example 1, and its magnetic properties were measured.

FIG. 5 shows the change in residual magnetic flux density (B _r ) with respect to compressive strain (ε _z ). As shown in FIG. 5, when ε _z is 0.05, B _r in the radial direction becomes larger than B _r in the axial direction, and as ε _z becomes further larger, B _r in the radial direction further increases. As you can see from this figure,
The change in the direction of easy magnetization from the axial direction to the radial direction is caused by ε _z
It progresses significantly in the range up to 0.05.

Furthermore, the inner circumference of the billet processed with ε _z = 0.69 (the part corresponding to billet B before compression processing),
A cubic sample of 4 mm on a side was taken out from the non-brass part in the same manner as described above, and its magnetic properties were measured. The magnetic properties in the radial and chordal directions are almost equal, B _r = 4.6kG, H _c = 2.8kOe, (BH) _nax =
4.0MG・Oe, axial direction B _r = 2.8kG, H _c = 2.1kOe,
(BH) _nax = 1.5MG・Oe.

In this way, the sample after compression processing has an easy magnetization direction in the radial direction at the outer periphery, and a planar anisotropic structure at the inner periphery.

Next, the billet processed with ε _z = 0.69 has an outer diameter of 23
After cutting to mm, the outer periphery was magnetized with 12 poles.
Magnetization is done using a 2000μF oil capacitor.
Pulse magnetization was performed at 2000V. The surface magnetic flux density at the outer periphery was measured with a Hall element and was 3.1 kG. This is a magnet suitable for extremely high performance outer circumferential magnetization.

Example 3 The extruded rod with a diameter of 31 mm obtained in Example 2 was cut into a length of 20 mm, and then machined to produce two cylindrical billets with a diameter of 24 mm and a length of 20 mm. This billet was freely compressed to a length of 10 mm at a temperature of 680°C using a lubricant. The two billets after processing were cut into a cylindrical body with an outer diameter of 30 mm, an inner diameter of 24 mm, and a length of 10 mm, and the two billets were overlapped to produce a cylindrical billet (billet A) with a length of 20 mm.

Next, the extruded rod with a diameter of 15 mm obtained in Example 2 was
After cutting to mm, it is machined to a diameter of 11 mm and a length of 20 mm.
A cylindrical billet (billet B) of mm was prepared.

Insert billet B into the hollow part of billet A,
Compression processing was carried out at a temperature of 680°C using a lubricant in the state shown in Fig. 2a. The mold used for compression processing was the same as in Example 1. The billet after compression processing was approximately cylindrical with a diameter of 30 mm and a length of 10 mm. This billet was cut to an outer diameter of 23 mm in the same manner as in Example 2, and the outer periphery was magnetized with 12 poles, and then the surface magnetic flux density of the outer periphery was measured. The surface magnetic flux density at the outer periphery was 3.1 kG.

Example 4 The extruded rod with a diameter of 31 mm obtained in Example 2 was cut to a length of 20 mm, and was machined to have an outer diameter of 30 mm, an inner diameter of 25 mm, and a length of 20 mm.
A 20 mm cylindrical billet (billet A) was prepared.

Next, the compound composition is 72% Mn, 27% Al and 1%
C was melted and cast to produce a cylindrical billet with a diameter of 50 mm and a length of 60 mm. After holding this billet at 1150℃ for 2 hours, it was heated from 1150℃ to 5700℃ for an average of 20℃.
Heat treatment was carried out by cooling at a cooling rate of °C/min and holding at 700 °C for 30 minutes. Next, extrusion processing up to a diameter of 28 mm was performed at a temperature of 720°C using a lubricant. This extruded rod was cut to a length of 20 mm and machined to an outer diameter of 25 mm.
A cylindrical billet (billet B) with a diameter of 22 mm, an inner diameter of 22 mm, and a length of 20 mm was prepared.

Billet B was placed in the hollow part of billet A, set in the state shown in FIG. 2c using the same mold as in Example 1, and compressed at a temperature of 680 DEG C. using a lubricant. The height of the billet after processing was 10 mm. This billet was cut to an outer diameter of 22 mm, and the outer periphery was magnetized with 8 poles in the same manner as in Example 2. The surface magnetic flux density of the outer periphery was measured. The surface magnetic flux density at the outer periphery was 2.9kG.

Example 5 A cylindrical billet (billet B) having an outer diameter of 22 mm, an inner diameter of 18 mm, and a length of 20 mm was prepared from pure iron.

Billet A is the same as billet A in Example 4.
Then billet B was put into the hollow part of billet A, and using the same mold as in Example 1, compression working was performed at a temperature of 680° C. using a lubricant in the state shown in FIG. 2d. Billet after compression processing (height is 10mm)
was cut to an outer diameter of 24 mm, the outer periphery was magnetized with 18 poles in the same manner as in Example 2, and the surface magnetic flux density of the outer periphery was measured. The surface magnetic flux density at the outer periphery was 3.2 kG.

Example 6 The extruded rod with a diameter of 31 mm obtained in Example 2 was cut into a length of 20 mm and machined to produce a cylindrical billet (billet A) with an outer diameter of 27 mm, an inner diameter of 21.8 mm, and a length of 20 mm.

Next, the compound composition is 69.4% Mn, 29.3% Al, 0.5
A cylindrical billet with an outer diameter of 14 mm, an inner diameter of 8 mm, and a length of 20 mm was prepared by melting and casting % C, 0.7% Ni, and 0.1% Ti. This billet was held at 1100° C. for 2 hours and then air-cooled to room temperature. A cylindrical billet (billet B) was prepared by putting copper with a diameter of 8 mm and a length of 20 mm into the hollow part of this billet.

Billet B was put into the hollow part of billet A and set in the state shown in FIG. 2f, and compression working was carried out at a temperature of 680 DEG C. using a lubricant using the same mold as in Example 1. Billet height after compression processing is 10cm.
It was hot.

The compressed billet was cut to an outer diameter of 26 mm, and the outer periphery was magnetized with 12 poles in the same manner as in Example 2. When we measured the surface magnetic flux density on the outer periphery, it was 3.1kG.
It was hot.

The above embodiment is a typical example shown in Fig. 2, but the lengths of billet A (1 in Fig. 2) and billet B (2 or 2 and 3 in Fig. 2) are not necessarily the same. It doesn't have to be. For example, the length of one billet may vary slightly before and after processing. Further, a billet made of a metal material may also exist outside billet A. Furthermore, rather than compressing the entire billet,
A method that does not deform part of the billet may also be used.
In some cases, billet A (or billet B)
may consist of two or more parts.

Effects of the Invention As described above, according to the present invention, it is possible to obtain a magnet that exhibits excellent magnetic properties in multipolar magnetization. Furthermore, in the method of the present invention, when cutting into a cylindrical shape, for example, if the center part of the magnet is made of a material with good machinability, it becomes easier to drill holes and to achieve accuracy. I can do it.

[Brief explanation of drawings]

Fig. 1 is a diagram schematically showing the formation of a magnetic path inside the magnet when the outer periphery of the cylindrical magnet is subjected to multipolar magnetization, and Fig. 2 is a diagram showing several states before compression processing of the present invention. FIGS. 3 and 4 are cross-sectional views of a part of a mold showing an example of compression processing of the present invention. FIG. 5 is a cross-sectional view of a part of a mold showing an example of compression processing of the present invention. FIG. 3 is a diagram showing changes in residual magnetic flux density (B _r ). 1... Billet A, 2, 3... Billet B,
4, 5... punch, 6... outer mold.

Claims (1)

[Scope of Claims] 1. A billet made of a metal material different from that of the alloy magnet is inserted into a hollow portion of a hollow billet made of a polycrystalline manganese-aluminum-carbon alloy magnet that has been made anisotropic in advance. , the two billets are integrated by compression processing in the axial direction of the hollow billet at a temperature of 530 to 830° C. until the two billets touch each other or further. -Production method of carbon-based alloy magnet. 2. Claim 1, wherein the billet made of a metal material is made of a magnetic material at least at the outer peripheral part.
A method for producing a manganese-aluminum-carbon alloy magnet as described in 2. 3 The hollow body-shaped billet is made of a polycrystalline manganese-aluminum-carbon alloy magnet having an easy magnetization direction in the axial direction of the hollow body, and the compressive strain in the axial direction of the hollow body during compression processing is the absolute value of the logarithmic strain. 0.05 or more, the method for manufacturing a manganese-aluminum-carbon alloy magnet according to claim 1 or 2. 4. A hollow body-shaped billet has a direction of easy magnetization parallel to a plane perpendicular to the axial direction of the hollow body, is magnetically isotropic within said plane, and is parallel to said axial direction and said plane. A method for manufacturing a manganese-aluminum-carbon alloy magnet according to claim 1 or 2, which comprises a polycrystalline manganese-aluminum-carbon alloy magnet that is anisotropic in a plane containing a straight line. 5. Claim No. 5, wherein the hollow body-shaped billet is a polycrystalline manganese-aluminum-carbon alloy magnet having an easy magnetization direction parallel to a straight line passing through an arbitrary point on a plane perpendicular to the axial direction of the hollow body. A method for manufacturing a manganese-aluminum-carbon alloy magnet according to item 1 or 2. 6. The manganese-aluminum according to claim 1 or 2, wherein the compression processing is performed with the outer periphery of the hollow billet restrained and at least a portion of the inner periphery free. -Production method of carbon-based alloy magnet. 7. After the compression process is performed with at least a portion of the outer and inner circumferences of the hollow billet free, the billet is further constrained with its outer circumference and at least a portion of its inner circumference free. A method for manufacturing a manganese-aluminum-carbon alloy magnet according to claim 1 or 2, which is processed by: 8. The method for producing a manganese-aluminum-carbon alloy magnet according to claim 1 or 2, wherein the hollow body has a cylindrical shape and the billet made of a metal material has a cylindrical shape. 9. The method for producing a manganese-aluminum-carbon alloy magnet according to claim 1 or 2, wherein the hollow body has a cylindrical shape and the billet made of a metal material has a cylindrical shape.