JPS62143409A - Manufacture of manganese-aluminum-carbon alloy magnet - Google Patents

Abstract

PURPOSE:To improve the distribution of magnetic characteristics by a method wherein a compressive processing in axial direction of a billet is performed at the prescribed temperature in such a manner that the compressive distortion of the outermost circumferential part of the billet will be made larger than that of the inside part. CONSTITUTION:Cutting and machining operations are performed on the rod obtained by extrusion-processing an Mn-Al-C alloy, and a cylindrical billet (not shown) is obtained. After a face anisotropic magnet has been formed by performing a free compressive processing on said billet 1, a cylindrical billet 1 is obtained by performing a machining work. Then, said billet 1 is inserted between a bottom force 4 and a fixing punch 2, maintained at the temperature of 530-830 deg.C, and a compressive processing is performed on the outer circumferential part only of the billet 1 using a movable punch 3. Then, after the outer circumference of the billet 1 has been machined, the outer circumference is magnetized. As a result, the magnetic characteristics in radial direction suitable for an outer circumferential multipolar magnetization can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing a permanent magnet, and in particular to a method for producing a high-performance multi-pole magnet using a polycrystalline manganese-aluminum II (Mn-Al-C) alloy magnet. The present invention relates to a method of manufacturing a Mn-C alloy magnet for magnetic use.

Conventional technology Mn-1-C alloy magnets are mainly composed of a face-centered tetragonal (τ phase, L1O type open circuit) structure, which is a ferromagnetic phase, and contain C as an essential constituent element. There are known multi-element alloy magnets, including ternary alloy magnets containing no additive elements other than impurities, and quaternary or higher alloy magnets containing a small amount of additive elements.

As for the manufacturing method thereof, in addition to those using casting and heat treatment, methods including a plastic working process such as extrusion processing are known. 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.

In addition, methods for producing multipolar magnetized alloy magnets using Mn-Ml-1 alloy magnets include known methods such as isotropic magnets, compression processing (registration number Ji+1011473), extrusion processing, etc. A uniaxially anisotropic polycrystalline Mn-Al-C alloy magnet obtained by free compression processing in the anisotropic direction (the obtained magnet is called a planar anisotropic magnet. JP-A-56-119
No. 762), one in which a part of a billet made of a planar anisotropic magnet is compressed (Japanese Unexamined Patent Publication No. 188103/1983), and a polycrystalline Mn-artificial-C alloy magnet that has been made anisotropic in advance. It is known that a hollow billet is subjected to a specific compression process (for example, JP-A-58-182206 to JP-A-68-182208).

The problem to be solved by the invention is a method in which a part of a billet made of the above-mentioned plane anisotropic magnet is subjected to compression processing (Japanese Patent Laid-Open No. 188103/1983), or a polycrystalline Mn-magnet which has been made anisotropic in advance. A method in which a hollow billet made of an l-1 alloy magnet is subjected to a specific compression process (for example, Japanese Patent Laid-Open No. 58-182206 to 58-182206).
8-182208), in which the outer periphery of a billet made of a polycrystalline Mn-Al-C alloy magnet that has been made anisotropic in advance is compressed in the axial direction of the billet. Although the processed portion has an easy magnetization direction in the radial direction, the distribution of magnetic properties of the processed portion is not necessarily suitable for outer circumferential multi-pole magnetization. In other words, only the outer periphery of the billet is compressed,
When multipole magnetizing is performed on the outer periphery, it is desirable that the distribution of magnetic properties in the radial direction of the processed portion be strongest at the outermost periphery.

An object of the present invention is to obtain a magnet with a good distribution of magnetic properties.

Means for Solving the Problems In order to solve the above problems, the present invention provides a method for solving the problems described above, in which a billet made of a polycrystalline Mn-Al-C alloy magnet having an easy magnetization direction parallel to a specific plane has a The billet is compressed in a direction perpendicular to the specific plane (axial direction) so that the compressive strain at the outermost peripheral portion of the billet is greater than that at the innermost portion.

Effect: By the method described above, that is, in the compression processing of the outer circumference of the billet, compression processing is performed in the axial direction of the billet so that the compression strain at the outermost circumference of the billet is greater than the compression strain at the innermost portion. By applying this method, unlike conventional methods, the distribution of magnetic properties in the radial direction within the magnet becomes suitable for outer circumferential multi-pole magnetization, and the magnetic properties of the magnet are improved.

Example The present invention provides a billet consisting of a polycrystalline Mn-Ml-C alloy magnet having an easy magnetization direction parallel to a specific plane.
At a temperature of 30 to 830°C, the outer circumference of the billet is strained in a direction perpendicular to the specific plane of the billet (in the axial direction ) is subjected to compression processing.

Furthermore, the billet has a direction of easy magnetization parallel to a plane perpendicular to the axial direction, is magnetically isotropic within the plane, and is magnetically isotropic within the plane including the axial direction and a straight line parallel to the plane. This is an anisotropic polycrystalline manganese-aluminum-carbon alloy magnet.

Most of the manufacturing method of the present invention is based on the above-mentioned known technology (Japanese Unexamined Patent Publication No. 6
Publication No. 8-188103 or JP-A-5B-1822
This method is almost the same as the method shown in Japanese Patent Nos. 06 to 58-182208).

In the compression processing of the known technique, only the outer peripheral portion of the billet is simply compressed in the axial direction of the billet.

On the other hand, in the compression processing of the present invention, in addition to the compression processing described above, compression processing is further performed in the axial direction of the billet so that the compression strain at the outermost peripheral portion of the billet is larger than the compression strain at the innermost portion. . In other words, only the outer periphery of the billet is compressed so that the compressive strain at the outermost periphery of the billet is the largest.

A specific example of this compression processing will be explained assuming that the shape of the billet is a cylindrical body. Figure 1 shows the cross section of the billet before processing. gl is the billet, 2 is a fixed punch, 3 is a movable punch,
4 is the lower mold. As shown in FIG. 1, the difference from the prior art is that the movable punch 3 contacts the billet (
The punch end face) is not a flat surface but an inclined surface.

By applying pressure to the billet 1 in the axial direction using the movable punch 3, only the outer peripheral portion of the billet is compressed in the axial direction, resulting in the state shown in FIG.

FIG. 1b [As shown, the height of the outermost portion of the billet after processing is smaller than the height of the innermost portion. In other words, compression processing was performed only on the outer periphery of the billet in the axial direction of the billet so that the compressive strain at the outermost periphery of the billet was greater than the compressive strain at the innermost portion. Compressive strain refers to strain in the axial direction of the billet.

Next, another typical compression processing example of the present invention will be explained assuming that the cross-sectional shape of the billet is ring-shaped.
Similar to the figure, a cross section before processing is shown. As shown in Figure 2 B, the difference from Figure 1 is that the punch end face of the movable punch 3 is flat, and the height of the outermost part of the billet before compression processing is greater than the height of the inner part. That's true.

Figure 2 shows the state after processing. The processed portion of the billet after processing has a substantially cylindrical shape, and the height of the outermost peripheral portion of the billet and the height of the innermost portion thereof are approximately the same. In this case as well, the billet was compressed in the axial direction so that the compressive strain at the outermost peripheral portion of the billet was greater than the compressive strain at the innermost portion.

As described above, the present invention is based on the above-mentioned known technology (Japanese Unexamined Patent Publication No. 5
Publication No. 8-188103 or Japanese Unexamined Patent Publication No. 1888-1822
06 to 5B-1522OS9), but by making the billet end face an inclined surface or the punch end face an inclined surface, in this particular compression processing, only the outer periphery of the billet can be processed. , the billet can be compressed in the axial direction so that the compressive strain at the outermost periphery of the billet is greater than the compressive strain at the innermost part, and the compression of this outermost periphery and the inner part By changing the difference in strain, the distribution of magnetic properties in the radial direction within the magnet can be made suitable for outer periphery multipole magnetization.

Even in a combination of the above two examples, the billet can be compressed in the axial direction so that the compressive strain at the outermost portion of the billet is larger than the compressive strain at the innermost portion. That is, this is a method of compressing the billet shown in Figure 2 (the billet end surface is an inclined surface) using the mold shown in FIG. 1 (the punch end surface is an inclined surface).

In the above example, the punch end face or billet end face was a sloped face, but there are also stepped faces (stepped shapes), flat + sloped faces, or a combination of the above, and the punch or billet end face that has an uneven shape has both sides. But it can be one-sided. What is necessary is to compress the billet in the axial direction so that the compressive strain at the outermost portion of the billet is greater than the compressive strain at the innermost portion. Therefore, the distribution of magnetic properties in the radial direction of the machined part of the magnet can be made suitable for outer periphery multipole magnetization.g Difference between compressive strain at the outermost periphery and compressive strain at the inner part The larger the value is, the higher the radial magnetic properties of the processed portion of the magnet become at the outermost periphery.

Regarding the possible temperature range of compression processing as mentioned above,
Although processing was possible in the temperature range of 63Q to 830°C, the magnetic properties were considerably degraded at temperatures exceeding 78°C. A more desirable humidity range is 560-760℃
8 Next, more specific embodiments of the present invention will be described.

Example 1 The blending composition was 69.5% Mn, 29.3% A1.0.
Melt and cast 5% C and 0.7% Ni, diameter 50+
A cylindrical billet with a diameter of 40 mm and a length of 40 mm was produced.

After holding this billet at 1100℃ for 2 hours, 60o
After cooling with air to 600°C for 30 minutes, heat treatment was performed by cooling at room temperature.

Using this billet, extrusion processing was performed at a temperature of 720°C, and the billet after iris processing had a diameter of 32 m.

It was 98 throats long. This extruded body was cut and machined to a diameter of 24 cm and a length of 40 cm. A cylindrical billet was prepared. Next, free compression processing was performed at a temperature of 680° C. up to a length of 20 lengths using a lubricant. The processed billet is a planar anisotropic magnet.

Next, using a mold as shown in FIG. 1, only the outer peripheral portion of the billet was compressed at a temperature of 680°C. The diameter of punch 2 (the inner diameter of punch 3 is 24 mm).The length of the boundary part of the billet after processing (the part with a diameter of 24 mm) is 16 mm.
After machining the rrrM billet to an outer diameter of 30 mm, the outer circumferential surface was magnetized in 24 ways.
Pulse magnetization was performed with ov. The surface magnetic flux density on the outer peripheral surface was measured using a Hall element.

For comparison, only the outer periphery of the billet having the above-mentioned planar anisotropic structure was compressed using the mold shown in FIG. 2 using a lubricant in the same manner as described above. The fixing punch 2 has a diameter of 24 mm.

The length of the outer periphery of the billet after processing was 15 mm. Furthermore, after performing VC+fJ machining in the same manner as above, it was magnetized and the surface magnetic flux density was measured.

Comparing the above two values, the value of the surface magnetic flux density of the magnet obtained by the method of the present invention was about 1.2 times that of the magnet produced for comparison.

Example 2 Using a billet made of a plane-anisotropic magnet obtained in Example 1, through a lubricant, at a temperature of 680°C! By pressing the center part of the billet with a punch with a diameter of 161 WR, the outer diameter is 37 mm, the inner diameter is 16 mm, and the length is 20 m.
A billet of m was prepared. The magnet after processing had an easy magnetization direction in the circumferential direction (circumferentially anisotropic magnet). This billet was compressed only on the outer periphery using the same mold shown in FIG. 1 as in Example 1.

After cutting the processed billet to an outer diameter of 30 mm, the outer periphery was magnetized with 24 poles in the same manner as in Example 1, and the surface magnetic flux density was measured.

For comparison, the billet made of the above-mentioned circumferentially anisotropic magnet was compressed only on the outer periphery using the same mold shown in FIG. 2 as in Example 1. 'Furthermore, after cutting in the same manner as above, it was magnetized and the surface magnetic flux density was measured.

Comparing the above two values, the surface magnetic flux density value of the magnet obtained by the method of the present invention was about 1.2 times that of the magnet produced for comparison.

Example 3 The composition was 69.4% Mn, 29.3% Mn 1.0.
Cylindrical billets each having a diameter of 50 and a length of 40 ran were prepared by melting and casting 5% C10, 7% Ni and 0.1% Ni, and the same heat treatment as in Example 1 was performed. Next, extrusion processing was performed at a temperature of 720° C. using a lubricant. The billet after processing had a diameter of 32 mm and a length of 98 mm. This extruded body was cut and machined to have a diameter of 24 mm and a length of 4 mm.
A 0-piece cylindrical billet was prepared, and in the same manner as in Example 1, a planar anisotropic magnet with a length of 20 mm was prepared by free compression processing. This magnet was machined to have an outer diameter of 34 m and an inner diameter of 10 mm.
A billet having a shape as shown in FIG. 2 was prepared, with a length of 20 ms at the outermost portion and a length of 15 fi at the position of diameter 24 mm. Next, this billet was coated with a lubricant, and only the outer periphery of the billet was molded using a mold as shown in Figure 2.
The billet was compressed to a length of 10 mm at the outer periphery at a temperature of .degree. In addition, in FIG. 2, the inner diameter of the movable punch is 24 mm.

After cutting the processed billet to an outer diameter of 30mm, Example 1
The outer periphery of 24 poles was magnetized in the same manner as above, and the surface magnetic flux density was measured.

For comparison, the planar anisotropic magnet described above was machined,
A cylindrical billet with an outer diameter of 34 rtan, an inner diameter of 10 rtan, and a length of 17.5 wM was prepared. Next, only the outer peripheral portion was compressed using a lubricant in the same manner as described above. The length of the outer periphery of the billet after processing was 10 cylinders.6 After cutting in the same manner as above, it was magnetized and the surface magnetic flux density was measured.

Comparing the above two values, the value of the surface magnetic flux density of the magnet obtained by the method of the present invention was about 1.2 times that of the magnet produced for comparison.

As mentioned above, regarding the composition of the Mn-human 1-C alloy magnet, N
Although we have shown only the four-element system with IL&AD and the six-element system with Ni and Ti additions, there are some differences in the magnetic properties of the magnets in the ternary system, which is the basic composition of Mn-Al-C alloy magnets. However, the above-mentioned improvement in magnetic properties was observed compared to the known compression processing method.

Polycrystalline Mn- with easy magnetization direction parallel to a specific plane
Examples using plane anisotropic magnets and circumferentially anisotropic magnets as Al-C alloy magnets have been shown; The same result was obtained even when using phantom anisotropy (circumferential anisotropy in the inner circumference), etc.

Furthermore, regarding the shape of the billet and punch end faces, an example of an inclined surface was shown, but improvements in magnetic properties compared to conventional compression processing were also observed with stepped shapes, flat surfaces + inclined surfaces, or a combination of the above. . Further, the process of forming the concave and convex shapes was the same on both end faces.

Effects of the Invention As described in the embodiments, the present invention provides a billet made of a polycrystalline Mn-Al-1 alloy magnet having a direction of easy magnetization parallel to a specific plane, and only on the outer periphery of the billet.
By compressing the billet in the axial direction so that the compressive strain at the outermost part of the billet is greater than that at the inner part, it exhibits high magnetic properties when multipole magnetization is applied to the outer periphery. This is what you get from magnets.

This method makes it possible to make the distribution of magnetic properties in the radial direction within the magnet suitable for outer periphery multi-pole magnetization, and to increase the difference between the compressive strain at the outermost periphery and the inner part. The more you do it, the greater the effect will be.

[Brief explanation of drawings]

FIGS. 1 and 2 are cross-sectional views of a part of a mold showing an example of compression processing of the present invention. 1... Billet, 2... Fixed punch, 3... φ... Movable punch, 4... Lower mold. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure ((L) (b)

Claims (4)

[Claims] (1) A billet made of a polycrystalline manganese-aluminum-carbon alloy magnet having an easy magnetization direction parallel to a specific plane is heated at a temperature of 530 to 830°C only on the outer periphery of the billet. A manganese-aluminum-carbon-based alloy magnet, characterized in that the billet is compressed in a direction perpendicular to the specific plane (axial direction) so that the compressive strain is greater than that of the inner part. Manufacturing method. (2) A plane in which the billet has a direction of easy magnetization parallel to a plane perpendicular to the axial direction, is magnetically isotropic within the plane, and includes a straight line parallel to the axial direction and the plane. Polycrystalline manganese-aluminum is anisotropic within
A method for manufacturing a manganese-aluminum-carbon alloy magnet according to claim 1, which comprises a carbon alloy magnet. (3) The method for manufacturing a manganese-aluminum-carbon alloy magnet according to claim 1, wherein the billet is a polycrystalline manganese-aluminum-carbon alloy magnet having an easy magnetization direction parallel to the radial direction. (4) The method for manufacturing a manganese-aluminum-carbon alloy magnet according to claim 1, wherein the billet is a polycrystalline manganese-aluminum-carbon alloy magnet having an easy magnetization direction parallel to the circumferential direction.