JPH0639674B2 - Method for producing manganese-aluminum-carbon alloy magnet - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a permanent magnet, and more particularly to Mn- for multipolar magnetization using a polycrystalline manganese-aluminum-carbon (Mn-Al-C) alloy magnet. The present invention relates to a method for manufacturing an Al-C alloy magnet.

2. Description of the Related Art Mn-Al-C based magnet alloys are a general term for Mn-Al-C based magnet alloys and Mn-Al-C based alloy magnets. The Mn-Al-C magnet alloy is 68 to 73 mass%.
(Hereinafter simply expressed as%) Mn and (1/10 Mn-6.
6) to (1 / 3Mn-22.2)% of C and the balance of Al, and a ternary system alloy containing no additional element other than impurities and a quaternary or more multicomponent magnet alloy containing a small amount of additional element Are known and are generic terms. Similarly, M
n-Al-C alloy magnet, face-centered tetragonal (tau phase, L1 ₀ type ordered lattice) is mainly ferromagnetic phase is composed of tissue, it comprises a C as essential constituent elements, additional elements other than the impurity Multi-component alloy magnets not containing ternary system and quaternary system containing a small amount of additional element are known, and they are collectively referred to.

As a manufacturing method thereof, there is a method including a warm plastic working step such as warm extrusion processing in addition to a method by casting and heat treatment. Especially, the latter has high magnetic properties, mechanical strength, weather resistance, machinability, etc. It is known as a method for producing an anisotropic magnet having excellent properties.

Further, as a method of manufacturing an alloy magnet for multipole magnetization using an Mn-Al-C alloy magnet, an isotropic magnet, a method by compression processing, a uniaxial method obtained by a known method such as warm extrusion processing in advance. Anisotropic polycrystalline Mn-Al-C alloy magnets that are subjected to warm free compression processing in the anisotropic direction (for example, Japanese Patent Laid-Open No. Sho 5
No. 6-119762), various types of plastic working that give compressive strain in the axial direction of a hollow body billet made of a Mn-Al-C magnet alloy (for example, Japanese Patent Laid-Open No. 58-1).
82206, JP-A-58-182207,
JP-A-58-182208), and Mn-Al-
A hollow billet made of a C-based magnet alloy and a billet made of a metal material are simultaneously subjected to compression processing (for example, JP-A-60-59720 and JP-A-60-59721).
Japanese Patent Laid-Open No. 60-59722).

Problems to be Solved by the Invention The shape of a multi-pole magnetizing magnet is generally a cylindrical body, and the main magnetizing is magnetizing as shown in FIG. FIG. 4 schematically shows the formation of a magnetic path (indicated by a broken line in the figure) inside the magnet when the outer peripheral surface of the cylindrical magnet is magnetized in multiple poles. Peripheral magnetization is called.

In the magnet obtained by various plastic workings that give compressive strain in the axial direction of the hollow-body-shaped billet made of the above-mentioned Mn-Al-C based magnet alloy, when the above-mentioned outer peripheral magnetization is applied, it locally occurs. Has anisotropy in the direction along the magnetic path, but when viewed as a whole, it does not anisotropy in the desired direction. Further, according to the above-described known method, the outer peripheral portion of the cylindrical magnet is anisotropic in the radial direction, and the inner peripheral portion is anisotropic in the circumferential direction (the chord direction, the same applies hereinafter). While the magnetic path is changing from the radial direction to the circumferential direction, it is not an anisotropic structure according to the method, and it is necessary to perform plastic working at a higher temperature twice or more.

The present invention is to obtain an anisotropic magnet having high magnetic properties.

Means for Solving the Problems In order to solve the above-described conventional problems, the present invention provides a hollow billet made of a manganese-aluminum-carbon magnet alloy at a temperature of 530 to 830 ° C. and a container. The cross-sectional shape of the hollow portion of the part is hollow, and the die is used in which the opening area of the container part is larger than the opening area of the bearing part. The hollow body-shaped billet is extruded to be stretched in the axial direction and the circumferential direction, and then the expanded hollow body-shaped billet is axially compressed to obtain a cross-sectional shape of the outer peripheral surface of the billet. Is molded into a (2n + 2) square (n = 1, 2, 3, ...) Shape.

By the above-described method, that is, by performing compression processing in the axial direction of the billet having the axially symmetrical shape after the specific extrusion processing described above, the cross-sectional shape of the outer peripheral surface of the billet is (2n +
2) By forming into a rectangular shape (n = 1, 2, 3, ...), it is possible to anisotropy along the magnetic path when the outer peripheral magnetization shown in FIG. 4 is applied, An anisotropic magnet showing high magnetic properties can be obtained.

Example The present invention provides a hollow-body-shaped billet made of a manganese-aluminum-carbon magnet alloy at a temperature of 530 to 830 ° C., in which the hollow section of the container section has a hollow cross-sectional shape, and the opening area of the container section is Using a die larger than the opening area of the bearing part, extrusion is performed with the axial direction of the billet parallel to the extrusion direction, and the hollow body-shaped billet is expanded in the axial direction and the circumferential direction by this first extrusion process. Then, the expanded hollow body billet is further compressed in the axial direction so that the cross-sectional shape of the outer peripheral surface of the billet is a (2n + 2) square (n = 1, 2, 3, ...).
...).

The above-mentioned two plastic workings do not necessarily have to be continuous plastic workings, and may be given by dividing into a plurality of times.

An example of the extrusion process of the present invention will be described below with reference to FIG. 1 in which the billet has a cylindrical shape. FIG. 1 (a) is a sectional view of a part of the die showing a state before extrusion, and similarly FIG. 1 (b) shows a state after extrusion. 1 is a cylindrical billet, 2 is a mandrel, 3 is a die,
4,5 are punches. The mandrel 2 and the dice 3 form a dice. In FIG. 1, 6 is a container part, which is a part for accommodating the billet 1 before extrusion. Reference numeral 7 denotes a bearing portion, which is a portion for accommodating the billet 1 after extrusion processing. 8 is a conical part. The opening area of the container portion 6 is the cross-sectional area of the cavity of the container portion 6 (perpendicular to the extrusion direction), which is almost the same as the cross-sectional area of the billet 1 in FIG. Is the cross-sectional area of the cavity of the bearing portion 7 (perpendicular to the extrusion direction), which is substantially the same as the cross-sectional area of the billet 1 in FIG. 1 (b).

In FIG. 1, since both the container portion 6 and the bearing portion 7 are circular with the extruding shaft as the center, in other words, the opening area of the container portion 6 is a ring shape defined by the outer diameter and the inner diameter of the container portion 6. Area. The cross-sectional shape of the hollow portion of the container portion 6 is the above-mentioned ring shape and is hollow. Similarly, the opening area of the bearing portion 7 is a ring-shaped area formed by the outer diameter and the inner diameter of the bearing portion 7. For example, the outer diameter of the container portion 6 is 40 mm, the inner diameter is 20 mm,
When the outer diameter of the bearing portion 7 is 50 mm and the inner diameter is 40 mm, the opening area of the container portion 6 is about 942 mm ² , and the opening area of the bearing portion 7 is about 707 mm ² . The cross-sectional shape of the hollow portion of the container portion 6 is a ring shape having an outer diameter of 40 mm and an inner diameter of 20 mm. In other words, the hollow portion of the container portion 6 has a hollow cross-sectional shape when the billet 1 is housed in the container portion 6 as shown in FIG. That is, there is a die constituent member (mandrel 2) in the central portion, a billet 1 is further outside thereof, and a die constituent member (die 3) is further outside thereof.

An example of the extrusion processing method will be described with reference to FIG. First, as shown in FIG. 2 (a), the cylindrical billet 1 '
To house. By pressing the billet 1'using the punch 4, it becomes as shown in FIG. 2 (b). Next, Fig. 2 (c)
As shown in FIG. 2, the billet 1 is newly accommodated in the container portion 6, and the billet 1 is pressurized by using the punch 4 in the same manner as described above, so that the state shown in FIG. Thereafter, extrusion processing is performed by repeating this.

As another extrusion processing method, in the state shown in FIG. 2 (c), the billet 1 is moved in the direction from the container part 6 to the bearing part 7 while pressing the billet 1 with the punches 4 and 5 (second part). In the figure, the state of the billet 1 is shown in FIG.
There is a method of performing extrusion processing by changing from (c) to FIG. 2 (d).

In FIG. 2 (a), the shape of the cylindrical billet 1'has a shape with an appropriate clearance so that the cylindrical billet 1'can be easily inserted into the container portion 6, but the cross section of the cylindrical billet 1 '( Plane perpendicular to the axial direction) and container part 6
The cross-sectional shapes of the hollow portions (the shape of the hollow portions when the die is cut along a plane perpendicular to the extrusion direction) are both ring-shaped.

Next, one example of compression processing is to make the billet into a cylindrical body,
The shape of the cross-section of the outer peripheral surface of the billet after compression processing will be described with reference to FIG. 3, assuming that it is square (when n = 1). Third
FIG. 1 (a) is a cross-sectional view of the state before compression processing as seen from the axial direction of the billet, 1 is a cylindrical billet, 4 is the tip of the punch, and when billet 1 is compression-formed, billet 1 To prevent spread to the center. An outer die 9 is a die for forming the outer peripheral surface of the billet 1 into a square shape by compression. FIG. 3 (b) is a sectional view showing a state after compression processing. As shown in FIG. 3, when the billet 1 is set and the punch 4 is used to perform compression processing in the axial direction of the billet 1, the cross-sectional area of the billet 1 gradually increases as the compression processing progresses. , A part of the outer peripheral surface of the billet 1 comes into contact with the outer mold 9,
The outer peripheral surface of the billet 1 substantially contacts the inner surface of the outer mold 9 by further progressing the compression processing. On the other hand, the inner peripheral surface contacts the surface of the punch 4. When compression processing is performed up to this point, the cross-sectional shape of the outer peripheral surface of the billet 1 becomes substantially square.

In this case, the maximum outer diameter of the billet 1 before compression processing is the size of the circle inscribed in the square on the inner surface of the outer die 9. In this case, before the compression processing, the compression processing is performed with a part of the outer peripheral surface of the billet 1 already constrained by the inner surface of the outer die 9.

In the above example, the change in the cross-sectional shape of the outer peripheral surface of the billet due to the compression processing is from circular to substantially square. Due to such a change, an anisotropic structure suitable for outer peripheral magnetization is obtained. In the compression processing process, the portion where the outer peripheral surface is restrained the earliest (the outer peripheral surface of the billet before processing, which is the portion closest to the inner surface of the outer die 9) is the portion having the easy magnetization direction in the peripheral direction, and finally the outer peripheral surface. The portion where is restricted or the portion where the outer peripheral surface is not restricted to the end (the portion which contacts the corner of the outer peripheral surface of the billet after processing) is a portion having an easy magnetization direction in the radial direction. The easy magnetization direction of the intermediate portion is a portion that sequentially changes from the circumferential direction to the radial direction. In this way, the shape of the inner surface of the outer mold 9 may be determined depending on how many poles are magnetized in the outer peripheral magnetization. That is, in the above-mentioned example, the shape of the cross section of the inner surface of the outer die 9 is a square, so that it has an anisotropic structure suitable for quadrupole magnetization. In other words, the cross-sectional shape of the outer peripheral surface of the billet after compression processing may be determined depending on how many poles are magnetized in the outer peripheral magnetization. The cross-sectional shape of the outer peripheral surface of the billet after compression processing is a (2n + 2) square shape, as described above, because the cross-sectional shape of the outer peripheral surface of the billet after processing needs to be an even polygonal shape.
= 1 for 4 poles, n = 2 for 6 poles ... The smaller n is, the clearer the anisotropic structure due to the above-mentioned position becomes, but the larger n becomes, the more unclear it becomes.

In the present invention, the (2n + 2) prism (n = 1, 2, 3, ...
The shape of (...) does not have to be a geometrically accurate (2n + 2) polygon, and there is no problem even if there is some chamfering.

As described in the above example, the present invention, when performing the compression processing in the axial direction of the billet having the axially symmetrical shape after the specific extrusion processing described above, changes the shape of the cross section of the outer peripheral surface of the billet using a mold or the like. By forming into a (2n + 2) prismatic (n = 1, 2, 3, ...) Shape, it is possible to anisotropy along the magnetic path when the outer peripheral magnetization shown in FIG. 4 is applied. An anisotropic magnet showing high magnetic properties is obtained.

Regarding the temperature range in which plastic working as described above is possible,
Machining was possible in the temperature range of 530 to 830 ° C, but at temperatures above 780 ° C, the magnetic properties deteriorated considerably. A more desirable temperature range was 560 to 760 ° C.

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

Example 1 In the composition, 69.5% Mn, 29.3% Al, 0.
5% C and 0.7% Ni were melt-cast and had an outer diameter of 20.
A cylindrical billet having a size of mm, an inner diameter of 4 mm and a length of 20 mm was produced. The billet was held at 1100 ° C. for 2 hours, then air-cooled to 600 ° C., held at 600 ° C. for 30 minutes, and then heat-treated to cool to room temperature. Next, extrusion processing as shown in FIG. 1 was performed at a temperature of 720 ° C. through a lubricant. However, the shape of the cavity of the die is a ring shape. The outer diameter of the container part of the die is 20mm, the inner diameter is 4mm, the outer diameter of the bearing part is 22mm, the inner diameter is 1
4 mm and X is 20 mm. The extruded billet has an outer diameter of 22 mm, an inner diameter of 14 mm, and a length of 26.7.
It is a cylindrical body of mm. The billet after processing was cut into a length of 20 mm. This billet was subjected to compression processing at a temperature of 680 ° C. through a lubricant using the outer mold 9 shown in FIG. The hollow portion of the outer die 9 has a square cross-sectional shape, the length of one side is 28 mm, and the diameter of the tip of the punch 4 is 14 mm.
And it is circular. Using such a mold, height 7.2
Compressed to mm.

The billet after compression processing was cut at the four corners to an outer diameter of 30 mm, and magnetized with four poles on the outer circumference. Magnetization is 2000μF
The surface magnetic flux density of the outer peripheral surface, which was pulse-magnetized at 1500 V, was measured with a Hall element using the oil condenser of No. 2.

For comparison, M of the same composition as the composition described above
n, Al, C, and Ni were melt-cast to produce a cylindrical billet having a diameter of 60 mm and a length of 40 mm. This billet is 11
After holding at 00 ° C. for 2 hours, a heat treatment of cooling to room temperature was performed. Then, a known extrusion process up to a diameter of 31 mm was performed at a temperature of 720 ° C. through a lubricant. This extruded rod is cut into a length of 20 mm and cut to have a diameter of 22 mm and a length of 20 mm.
A mm billet was prepared. This billet at 680 ° C
Free compression processing was performed at a temperature of up to 7.2 mm in the axial direction of the cylinder. The processed billet (plane anisotropic magnet) was cut and magnetized in the same manner as above, and the surface magnetic flux density was measured.

Comparing the values of the surface magnetic flux densities of the above two, 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 69.4% of Mn, 29.3% of Al, and 0.
5% C, 0.7% Ni and 0.1% Ti were melted and cast to prepare a cylindrical billet having an outer diameter of 26 mm, an inner diameter of 14 mm and a length of 20 mm. This billet is 1100 ℃
After being held for 2 hours at 80 ° C., it was air-cooled to 600 ° C., held at 600 ° C. for 30 minutes, and then allowed to cool to room temperature. Next, extrusion processing as shown in FIG. 1 was performed at a temperature of 720 ° C. through a lubricant. However, the shape of the cavity of the die is a ring shape. The outer diameter of the container portion of the die is 26 mm, the inner diameter is 14 mm, the outer diameter of the bearing portion is 22 mm, the inner diameter is 14 mm, and X is 20 mm.
The billet after extrusion is a cylindrical body having an outer diameter of 22 mm, an inner diameter of 14 mm and a length of 33.3 mm. The billet after processing was cut into a length of 20 mm. This billet was 680 sized through a lubricant using the outer mold 9 shown in FIG.
Compression processing was performed at a temperature of ° C. The outer die 9 has a square cross-section on the inner surface, the length of one side is 28 mm, and the diameter of the tip of the punch 4 is 14 mm, which is circular. Using such a mold, compression processing was performed to a height of 7.2 mm.

The billet after compression processing was cut at the four corners to an outer diameter of 30 mm, and magnetized with four poles on the outer circumference. Magnetization is 2000μF
Pulse-magnetized at 1500 V by using the oil condenser of. The surface magnetic flux density on the outer peripheral surface was measured with a Hall element.

For comparison, M of the same composition as the composition described above
n, Al, C, Ni and Ti are melt-cast and have a diameter of 50 m
A cylindrical billet having a length of m and a length of 40 mm was produced. The billet was held at 1100 ° C. for 2 hours and then heat-treated by allowing it to cool to room temperature. Then, a known extrusion process was performed at a temperature of 720 ° C. to a diameter of 24 mm through a lubricant. This extruded rod is cut to a length of 20 mm and cut to a diameter of 22 mm,
A cylindrical billet having a length of 20 mm was produced. This billet was freely compressed at a temperature of 680 ° C. in the axial direction of the cylinder to a height of 7.2 mm. The processed billet (plane anisotropic magnet) was cut and magnetized in the same manner as above, and the surface magnetic flux density was measured.

Comparing the values of the surface magnetic flux densities of the above two, 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, Al, C and Ni having the same compounding composition as in Example 1 were melt-cast to prepare a cylindrical billet having a diameter of 50 mm and a length of 30 mm. The billet was held at 1100 ° C. for 2 hours and then heat-treated by allowing it to cool to room temperature.

Then, a known extrusion process was performed at a temperature of 720 ° C. to a diameter of 24 mm through a lubricant. The extruded rod was cut into a length of 20 mm and cut to form a cylindrical billet (billet X) having an outer diameter of 20 mm, an inner diameter of 4 mm and a length of 20 mm. The extruded rod was cut into a length of 35 mm and cut into a cylindrical billet (billet Y) having a diameter of 23 mm and a length of 35 mm. Using this billet Y, free compression processing was performed in the axial direction of the billet at a temperature of 680 ° C. via a lubricant. The length of the billet after processing was 20 mm. This billet (plane anisotropic magnet) is cut and cut in the same manner as the billet X to have an outer diameter of 20 mm and an inner diameter of 4
A cylindrical billet (billet Y) having a length of 20 mm and a length of 20 mm was produced. Next, the same extrusion processing and compression processing as in Example 1 were performed. That is, the billet X and the billet Y were extruded through a lubricant at a temperature of 720 ° C. as shown in FIG. However, the shape of the cavity of the die is a ring shape. The outer diameter of the container part of the die is 20m
m, inner diameter is 4mm, outer diameter of bearing is 22mm,
The inner diameter is 14 mm and X is 20 mm. The billet after extrusion has a cylindrical shape with an outer diameter of 22 mm, an inner diameter of 14 mm and a length of 26.7 mm. The billet after processing was cut into a length of 20 mm. This billet was subjected to compression processing at a temperature of 680 ° C. through a lubricant using the outer mold 9 shown in FIG. The cross-sectional shape of the inner surface of the outer die 9 is square, the length of one side is 28 mm, and the diameter of the tip of the punch is 14 mm, which is circular. Using such a mold, compression processing was performed to a height of 7.2 mm.

The billet after compression processing was cut at the four corners to an outer diameter of 30 mm, and magnetized with four poles on the outer circumference. Magnetization is 2000μF
Pulse-magnetized at 1500 V by using the oil condenser of. Measure the surface magnetic flux density of the outer peripheral surface with a Hall element,
The value was compared with the value of the surface magnetic flux density of the magnet manufactured for comparison in Example 1.

Comparing the values of the above surface magnetic flux densities, the values of the magnet obtained in Example 3 are almost the same in the billet X and the billet Y, and about 1. It was eight times.

The magnets obtained by the method of the present invention obtained in Examples 1, 2 and 3 were measured by magnetic torque. As a result, as described above, the easy magnetization direction of the outer peripheral portion of the billet was the radial direction at the corners of the billet after compression processing. Along, along the circumference in the middle,
It was found that between them, there was a continuous change from the radial direction to the circumferential direction.

As described above, regarding the composition of the Mn-Al-C based magnet alloy, N
Only the i-added quaternary system and the Ni- and Ti-added quaternary system are shown. However, a ternary system which is a basic magnet of an Mn-Al-C alloy magnet or a known element containing an additive element other than the above Regarding the multi-component system, although a slight difference was observed in the magnetic characteristics of the magnet after plastic working, the improvement in magnetic characteristics as described above was recognized as compared with the conventional method.

EFFECTS OF THE INVENTION As is clear from the above description, according to the present invention, a hollow body-shaped billet made of a manganese-aluminum-carbon magnet alloy has a hollow cross-sectional shape of a hollow portion of a container portion at a temperature of 530 to 830 ° C. And using a die in which the opening area of the container is larger than the opening area of the bearing,
Extrusion is performed with the axial direction of the billet parallel to the extrusion direction, and the hollow body-shaped billet is expanded in the axial direction and the circumferential direction by the first extrusion process, and then further expanded. By compressing the billet in the axial direction, the cross-sectional shape of the outer peripheral surface of the billet is (2n +
2) A method of manufacturing a magnet that exhibits high magnetic characteristics when it is molded into a rectangular shape (n = 1, 2, 3, ...) And is magnetized on the outer circumference. Compared with the magnet by the method, when magnetized on the outer circumference, it shows better magnetic characteristics than the magnet by the conventional method. Furthermore, the outer circumference of the magnet has a direction of easy magnetization in the radial direction, and the inner circumference In order to obtain a structure having an easy magnetization direction in the circumferential direction, at least two or more plastic workings were required in the conventional method, but in the method of the present invention, it is only necessary to perform plastic working once, and a magnet having a more desirable anisotropic structure can be obtained. Obtainable.

[Brief description of drawings]

1A and 1B are partial sectional views of a mold showing an example of extrusion processing of the present invention, and FIGS. 2A to 2D are partial sectional views of a mold showing an example of extrusion method of the present invention, 3a and 3b are cross-sectional views of a mold used in the compression processing of the embodiment of the present invention, and FIG. 4 is a magnetic path inside the magnet when the outer peripheral surface of the cylindrical magnet is multi-pole magnetized. It is a figure which shows formation typically. 1, 1 '... Billet, 2 ... Mandrel, 3 ... Die, 4, 5 ... Punch, 6 ... Container part, 7 ... Bearing part, 9 ... External mold.

Claims (3)

[Claims] 1. A hollow body-shaped billet made of a manganese-aluminum-carbon magnet alloy has a temperature of 530 to 830 ° C.
At this temperature, the hollow part of the container part has a hollow cross-section and the opening area of the container part is larger than that of the bearing part. The cross-section of the outer peripheral surface of the billet is obtained by expanding the hollow body billet by the extrusion process in the axial direction and the circumferential direction, and further compressing the expanded hollow body billet in the axial direction. Manganese-aluminum-characterized in that it is molded into a (2n + 2) prismatic shape (n = 1, 2, 3, ...).
Manufacturing method of carbon alloy magnets. 2. The manganese-aluminum-carbon according to claim 1, wherein the compression processing is carried out with a part of the outer peripheral surface of the expanded hollow billet being constrained. -Based alloy magnet manufacturing method. 3. The compression processing comprises compressing the expanded hollow body-shaped billet in a state where at least a part of the outer peripheral surface and the inner peripheral surface of the billet is free, and then the outer peripheral surface of the billet is constrained. The method for producing a manganese-aluminum-carbon based alloy magnet according to claim 1, wherein