JPS62243753A - Manufacture of manganese-aluminum-carbon alloy magnet - Google Patents

Abstract

PURPOSE:To obtain an anisotropic magnet showing high magnetic properties, by subjecting an Mn-Al-C magnetic alloy to compression working so that compressive strain is lower in the outside peripheral part than in the inside peripheral part and by forming the inside peripheral surface of a billet into recessed and projecting shape by means of further compression working. CONSTITUTION:A hollow billet 1 composed of Mn-Al-C magnetic alloy is set up so that its inside peripheral surface is in contact with the surface of a punch 2 of recessed and projecting shape while its outside peripheral surface is in contact with the inside peripheral surface of a die 4. The billet 1 is subjected to compression working at 530-830 deg.C by the use of the punch 2 so that compressive strain in the outside peripheral part is lower than that in the inside peripheral part and, by further compression working, the inside peripheral surface of the billet 1 is formed into recessed and projecting shape.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing permanent magnets, and in particular to multipolar magnetization using polycrystalline manganese-aluminum-carbon X (In-M1-C) alloy magnets. The present invention relates to a method for manufacturing Mn-4-0 series alloy magnets.

Conventional technology Mn-5 l-C magnet alloy C, Mn of 68 to 73 mass Chi (hereinafter simply expressed as Chi) and (1710MN-6,8)
~(173MN-22,2)% of C and the balance of mulch, ternary alloys containing no additive elements other than impurities, and quaternary or higher multi-component alloys containing small amounts of additive elements are known. This is a general term for these. Similarly, Mn-
Human/-C alloy magnets are mainly composed of a face-centered tetragonal (γ phase, L1g type regular lattice) structure, which is a ferromagnetic phase.
There are known multi-component alloy magnets, including ternary alloy magnets containing as essential constituent elements, and containing no additional elements other than impurities, and quaternary or higher alloy magnets containing small amounts of additive elements. .

In addition to casting and heat treatment, manufacturing methods include extrusion and other plastic working processes, and the latter in particular has excellent properties such as high magnetic properties, mechanical strength, weather resistance, and machinability. It is known as a method for manufacturing anisotropic magnets.

In addition, methods for producing multipolar magnets using Mn-Mul-C alloy magnets include isotropic magnets, compression processing, and hollow bodies made of Mn-Mul-C alloy magnets. Various types of plastic working that apply compressive strain in the axial direction of shaped billets (for example, JP-A-58-192303, JP-A-58-1)
92306゜Patent No. 58-192306), and Mn
A method is known in which a hollow billet made of an alloy for M-E-0 series magnets and a billet made of a metal material are simultaneously compressed (for example, Japanese Patent Laid-Open No. 60-59055).

Problems to be Solved by the Invention Multi-pole magnetizing magnets are generally cylindrical in shape, and the main magnetization is as shown in FIG. Figure 6 schematically shows the formation of a magnetic path inside the magnet when the inner peripheral surface of a cylindrical magnet is magnetized with multiple poles. In magnets obtained by various types of plastic working that apply compressive strain in the axial direction of the hollow billet made of the Mn-Ml-C magnet alloy described above, when internal magnetization is applied, localized magnetization occurs. is anisotropic in the direction along the magnetic path,
When viewed as a whole, anisotropy is not achieved in the desired direction. In addition, according to the method described above, the inner circumference of the cylindrical magnet is anisotropic in the radial direction, and the outer circumference is anisotropic in the circumferential direction (chord direction, hereinafter referred to as the same), but the magnetic path is In the middle of the change from the radial direction to the circumferential direction, it is necessary to perform plastic working at a higher temperature two or more times, rather than creating an anisotropic structure along that direction.

Means for Solving the Problems In order to solve the above-mentioned conventional problems, the present invention provides the following:
A hollow billet made of Mn-Ml-C magnet alloy is compressed so that the compressive strain at the outer circumference is smaller than that at the inner circumference, and the inner circumference of the billet is further compressed by compression. It is molded into an uneven shape.

Operation By using the method described above, that is, by compressing the billet so that the compressive strain on the outer circumferential portion is smaller than that on the inner circumferential portion, and further forming the inner circumferential surface of the billet into an uneven shape by compression processing, the billet as shown in Fig. 5 is produced. When the inner periphery is magnetized as shown, anisotropy can be achieved along the magnetic path, and an anisotropic magnet exhibiting high magnetic properties can be obtained.

EXAMPLE The present invention produces a hollow billet made of an Mn-Ml-1 alloy for magnets at a temperature of 630 to 830°C so that the compressive strain at the outer circumference is smaller than the compressive strain at the inner circumference. The billet is subjected to compression processing, and the inner circumferential surface of the billet is shaped into an uneven shape by compression processing.

The compression process described above does not necessarily have to be continuous compression process, and may be divided into multiple times.

The method of performing compression processing so that the compression strain is smaller than the compression strain of the inner peripheral portion will be explained separately.

First, an example of forming the inner circumferential surface of a billet into an uneven shape by compression processing will be described with reference to FIG. 1, assuming that the billet has a cylindrical shape. Figure 1 (&) shows a cross section of the billet before compression processing, viewed from the axial direction, and 1 indicates Mn-Mul-C
A circular cylindrical billet made of an alloy for magnets, 2 is a punch, which has an uneven shape for shaping the inner circumferential surface of the billet 1, and 4 is a mold, which restrains the outer circumferential surface of the billet 1. This is a mold for FIG. 1(b) shows the state after compression processing. As shown in (b), as the compression process progresses, the cylindrical billet 1 becomes smaller in diameter, and part of its inner circumferential surface comes into contact with the surface of the punch 2, and is further compressed. As the machining progresses, the inner circumferential surface of the billet 1 almost comes into contact with the surface of the punch 20, while the outer circumferential surface remains in contact with the inner surface of the mold 4, as shown in FIG. It is not necessary to perform the compression process to the state shown in (b), and a part of the inner circumferential surface of the billet 1 may be finished by the punch 2. In other words, the unevenness may be formed on the inner circumferential surface of the billet 1. In this case, the minimum inner diameter of billet 1 before compression is punch 2.
It is the size that touches the convex part of the surface. In this case, a part of the inner circumferential surface of belay I 1 is removed by punch 2 before compression processing.
Compression processing is performed while being restrained by the surface of the

As described above, the presence of the unevenness on the surface of the punch 2 causes unevenness to be formed on the inner circumferential surface of the billet 1 after compression processing. In the compression processing process, the part where the inner circumferential surface is constrained earliest (the recessed part of the inner circumferential surface of the billet 1 after processing) is the part which has an easy magnetization direction in the circumferential direction, and the inner circumferential surface is constrained last. or the part where the inner peripheral surface is not restrained until the end (
The convex portion on the inner circumferential surface of the belay Ito 1 after processing (the portion closest to the center) becomes a portion having an easy magnetization direction in the radial direction.

The easy magnetization direction of the intermediate portion changes sequentially from the circumferential direction to the radial direction. In other words, in FIG. 1, the direction of easy magnetization gradually and continuously changes from the inner circumference of the pilent 1 in the direction along the curved surface of the concave part of the inner circumference of the billet 1 formed by the convex part on the surface of the punch 2. . Therefore, the number of concave and convex portions may be determined depending on whether fine pole magnetization is performed during inner circumference magnetization. In Figure 1, there are six convex parts on the inner peripheral surface of billet 1 after processing, so the magnet has an anisotropic structure suitable for six-pole magnetization, and the parts that correspond to the protrusions after processing are on the inner circumference. It becomes the pole part in magnetization.

As described in the above example, in the present invention, when compressing the billet 1 in the axial direction, the mold 4 or the like is used to mold and compress the billet 1 so that the inner peripheral surface becomes uneven. By doing so, it is possible to obtain a magnet having an anisotropic structure that exhibits high magnetic properties when internally magnetized.

Next, a specific example of compressing so that the compressive strain at the outer circumference is smaller than the compressive strain at the inner circumference will be explained using FIG. 3, assuming that the billet 1 has a cylindrical shape.
FIG. 3 shows a cross section of the unprocessed state viewed from a direction perpendicular to FIG. 1. 1 is a billet, 2.3 is a punch, and 4 is a mold. As shown in FIG. 3, the surfaces of the punches 2 and 3 that contact the billet 1 (punch end surfaces) are not flat surfaces but sloped surfaces. Using this punch 2 and punch 3,
By applying pressure in the axial direction of the billet 1, the billet 1 is compressed in the axial direction. Billet 1 after compression processing
The height of the outer circumference is greater than the height of the inner circumference. In other words, the billet 1 is compressed in the axial direction so that the compressive strain on the outer circumferential portion of the billet 1 is smaller than the compressive strain on the inner circumferential portion. Compressive strain refers to strain in the axial direction of billet 1.

Next, another specific example of compressing so that the compressive strain on the outer circumferential portion is smaller than the compressive strain on the inner circumferential portion will be described with reference to FIG. 4, assuming that the cross-sectional shape of the billet 1 is ring-shaped. FIG. 4 shows a cross section before processing, similar to FIG. 3. As shown in Fig. 4, the difference from Fig. 3 is that the punch end faces of punches 2 and 3 are flat, and the height of the outer periphery of billet 1 before compression processing is smaller than the height of the inner periphery. be. After processing, the billet 1 has a substantially cylindrical shape, and the height of the outer circumferential portion of the billet 1 and the height of the inner circumferential portion of the billet 1 substantially match. In this case as well, the billet 1 was compressed in the axial direction so that the compressive strain on the outer circumferential portion of the billet 1 was smaller than the compressive strain on the inner circumferential portion.

As mentioned above, by making the end face of billet 1 an inclined face or the end face of punch 2.3 an inclined face, in this particular compression process, the compressive strain at the outer circumference of billet 1 is lower than the compressive strain at the inner circumference. Compression processing can be performed in the axial direction of the billet 1 so that it becomes smaller.

Even in a combination of the above two examples, the billet 1 can be compressed in the axial direction so that the compressive strain on the outer circumferential portion of the billet 1 is smaller than the compressive strain on the inner circumferential portion.

That is, this method uses the punches 2, 3 and mold 4 shown in FIG. 3 to compress the billet shown in FIG. 4.

″ In the above example, the punch 2.3 end face or billet 1
The end surface was a sloped surface, but there were also stepped surfaces (stepped shape),
There may be a flat surface + an inclined surface or a combination of the above, and the end surface of the punch 2.3 or the billet 1 to be made uneven may be either double-sided or single-sided. What is necessary is to compress the billet 1 in the axial direction so that the compressive strain on the outer circumference of the billet 1 is greater than the compressive strain on the inner circumference.

Regarding the possible temperature range of compression processing as mentioned above,
Processing was possible in the temperature range of 630 to 830°C, but at temperatures exceeding 780°C, the magnetic properties deteriorated considerably. The preferred temperature range is 660 to 7.
The temperature was 60°C.

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

Example 1 (Fig. 2, Fig. 4) The blend composition is ee, s% Mn, and 29.3% 5L.

Melting and casting 0.6% C and 0.7% N1, outer diameter 3
A billet 1 of 0 wire, an inner diameter of 24 fins, an outer circumference length of 20 m, an inner circumference length of 26 fins, and an inclined end surface was prepared. After holding this billet 1 at 1100°C for 2 hours,
After air-cooling to 00°C, holding at aoo°C for 30 minutes, heat treatment was performed by cooling to room temperature.

Next, compression processing was performed at a temperature of 680° C. using a punch 2°3 and a mold 4 shown in FIGS. 2 and 4 through a lubricant. Figure 2 is a cross-sectional view of the outer mold similar to Figure 1, υ, (inner diameter of outer mold 4) Dk = 30 m, X
A = 8 tx, (radius of convex part of punch 2) RB =
2.5 wm, the punch diameter Dp=16 m, and the punch 2 has eight convex portions on its surface. 2 and 3 are punches having stepped portions or holes in which concave and convex surfaces fit into each other, and can be moved in the vertical direction in the figure.

Using such punches 2 and 3 and the mold 4, compression processing was performed until the cavity in the mold 4 was almost completely eliminated.

After cutting the processed billet 1 to an inner diameter of 20 tm, the inner circumference was magnetized with eight poles. For magnetization, a 2000 μF oil capacitor was used, and pulse magnetization was performed at 15 oov.

The surface magnetic flux density on the inner peripheral surface was measured with a Hall element◇ For comparison, Mn and human l of the above-mentioned formulation composition.

C and N1 are melted and cast, diameter 24 tax, length 2
A round cylindrical billet 1 was produced. The same heat treatment as above was carried out. This billet 1 was subjected to free compression processing at a temperature of 680° C. in the axial direction of the cylinder to a length of 10 wIA. After cutting the processed billet 1 in the same manner as above, it was magnetized and the surface magnetic flux density was measured. Comparing the surface magnetic flux density values of 0 or more, the value of the magnet obtained by the method of the present invention is , which was about 1.7 times that of a magnet prepared for comparison.

Example 2 (Figure 2) The blend composition is 69.4% Mn and 29.3% Mul.

Billet 1 having an outer diameter of 30 fl, an inner diameter of 24 fi, and a length of 20 strips was prepared by melting and casting 0.6% C, 0.7% N1, and 0.1 tin. This billet 1 was subjected to the same heat treatment as in Example 1. Next, using the punches 2 and 3 and the mold 4 shown in FIGS. 2 and 3, 68
Compression processing was performed at a temperature of 0° C. until the cavity in the mold 4 was almost completely eliminated. Note that the dimensions of each part shown in FIG. 2 are the same as in Example 1, and the inclination angle (α) is 20°.

After cutting the processed billet 1 to an inner diameter of 20mm in the same manner as in Example 1, the inner circumference was magnetized with 8 poles, and the surface magnetic flux density was measured.

For comparison, Mn and Mue of the above-mentioned compounding composition.

Melt and cast C, Ni and T1, diameter 24 mm, length 20 mm.
A cylindrical billet 1 having a diameter of m was produced and subjected to the same heat treatment as described above. This billet 1 was subjected to free compression processing at a temperature of 680°C to a length of 10III in the axial direction of the cylinder. After cutting the processed billet 1 in the same manner as described above, it was magnetized and the surface magnetic flux density of the billet 1 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 this example was about 1.7 times that of the magnet produced for comparison.

As a result of magnetic torque measurement, the magnets obtained by the method of the present invention obtained in Examples 1 and 2 showed that the direction of easy magnetization continuously changed from the radial direction to the circumferential direction along the surface of the recessed portion, as described above. was confirmed.

As mentioned above, regarding the composition of the Mn-Ml-C alloy for magnets,
Although only the four-element system with N1 addition and the six-element system with Ni and Ti added are shown, it is possible to use the ternary system, which is the basic composition of Mn-Ml-C alloy magnets, or the known ones containing additive elements other than the 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.

Furthermore, as for the shape of the billet 1 and the punches 2 and 3 end faces, an example of an inclined surface is shown, but even a stepped shape, a flat surface, an inclined surface, or a combination of the above can also improve magnetic properties compared to conventional compression processing. was recognized.

Effects of the Invention As is clear from the detailed explanation above, the present invention provides a hollow billet made of an Mn-Ml-C alloy for magnets.
It is compressed at a temperature of 30 to 830°C so that the compressive strain on the outer circumferential part is smaller than that on the inner circumferential part, and the uneven part is formed on the inner circumferential surface of the bereud by the compression process. When magnetized on the inner periphery, it is possible to obtain a magnet that exhibits high magnetic properties.Comparing the magnet produced by the method of the present invention with the magnet produced by the conventional method, it is found that when magnetized on the inner periphery, the magnet exhibits high magnetic properties. In order to obtain a structure that exhibits superior magnetic properties than the magnet produced by the above method, and further has a structure in which the inner periphery of the magnet has an easy direction of magnetization in the radial direction, and the outer periphery has an easier direction of magnetization in the circumferential direction, the conventional method is used. The method required at least two or more plastic workings, but the method of the present invention requires only one plastic working.

Therefore, a magnet having a more desirable anisotropic structure can be obtained.

[Brief explanation of drawings]

Figures 1 to 4 show punches used in embodiments of the present invention;
FIG. 6, a cross-sectional view of the mold part, is a diagram schematically showing a magnetic path caused by multi-pole magnetization on the inner circumference of a cylindrical magnet. 1...Billet, 2,3...Punch,
4...Bent mold, α...Inclination angle, Agent's name: Patent attorney Toshio Nakao and 1 other person 1st
Figure (0,) (b) Figure 2 Figure 3 Figure 4

Claims (3)

[Claims] (1) A hollow billet made of a manganese-aluminum-carbon alloy for magnets is compressed at a temperature of 530 to 830°C so that the compressive strain on the outer circumference is smaller than the compressive strain on the inner circumference, Furthermore, the method for manufacturing a manganese-aluminum-carbon alloy magnet includes forming the inner circumferential surface of the billet into an uneven shape by compression processing. (2) The method for manufacturing a manganese-aluminum-carbon alloy magnet according to claim (1), wherein the compression processing is performed while the outer periphery of the billet is restrained. (3) The method for manufacturing a manganese-aluminum-carbon alloy magnet according to claim (1), wherein the compression processing is performed while a portion of the inner circumference of the billet is restrained.