JPH0663067B2 - 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 magnetizing multipoles 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.

Prior art alloys for Mn-Al-C magnets contain 68 to 73 mass% (hereinafter simply referred to as%
Mn) and (1 / 10MN-6.6) to (1 / 3MN-22.
2) Multi-component magnet alloys composed of 3% C and the balance Al, ternary system containing no additional elements other than impurities, and quaternary system containing a small amount of additional elements are known. It is a thing. Similarly, Mn-Al-C alloy magnet, face-centered tetragonal predominantly ferromagnetic phase (gamma-phase, L1 ₀ type ordered lattice)
It is known that there are ternary alloy magnets of ternary system or more containing ternary system containing no additional element other than impurities and quaternary system containing a small amount of additional element, These are generic names.

Conventionally, the manufacturing method is such that the outer periphery of a hollow body billet made of an alloy for Mn-Al-C magnets is constrained by an outer mold,
A punch having a flat compression surface was used for compression processing (Japanese Patent Laid-Open No. 192306/58).

Problems to be Solved by the Invention According to the above-described conventional manufacturing method, the billet is subjected to substantially the same compressive strain in both of the billet and the outer peripheral portion thereof. It becomes a substantially straight line in the radial direction like the line A.

Therefore, in this state, even if S and N are magnetized on the inner circumference or the outer circumference as shown in the figure, the ideal semi-circular B line, which is the ideal easy magnetization direction array in that case, is too much. Since the arrangement of the easy magnetization direction is different, a strong magnetic force could not be obtained even when the magnetizing work was performed.

Therefore, in the above-mentioned conventional example, as shown in FIG.
Before magnetizing N, the inner peripheral portion of the compressed billet is compressed again to bring the easy magnetization direction array close to a substantially semicircular shape as shown by line B in FIG. 5 of the present application, and then to the inner periphery. I was supposed to do the magnetization work.

However, in the conventional case, in order to obtain such a substantially semi-circular easy direction alignment, the inner circumference or the outer circumference of the billet must be compressed again after the compression of the billet, resulting in poor workability. It was

Therefore, the present invention is to magnetize S, N on the inner peripheral portion of the billet, and an object thereof is to make it possible to easily obtain a substantially semicircular easy magnetization direction array by one compression operation. Is.

In order to achieve this object, the present invention provides manganese-
A hollow body-shaped billet made of an aluminum-carbon magnet alloy is configured to be compressed by axially pressing the punch at a temperature of 530 to 830 ° C., and the punch compresses the billet from the end portion in the axial direction. A first compression surface, and a projecting portion projecting inwardly of the billet from a central portion of the first compression surface. The first compression surface has a billet extending from an outer peripheral portion toward an inner peripheral portion. Of the billet is compressed by the inclined first compression surface so that the compression strain of the inner peripheral portion of the billet is larger than the compression strain of the outer peripheral portion of the billet. , A second uneven surface on its outer surface
The second compression surface is used to mold the inner peripheral surface of the billet into an uneven shape.

With the above configuration, when the hollow body billet made of a manganese-aluminum-carbon magnet alloy is compressed in the axial direction by the punch, the first compression surface of the punch moves from the outer peripheral portion toward the inner peripheral portion. Since the billet has an inclination that approaches the end of the billet, the compressive strain of the billet is greater than the compressive strain of the billet of the billet, and due to the axial compression of the billet by the first compression surface, the billet is compressed. The inner peripheral surface of the billet is pressed against the second compression surface of the protruding portion of the punch and receives a compressive force. As a result, the inner peripheral portion of the billet after compression has a substantially semi-circular easy magnetization direction alignment. Is easily formed by one-time compression, and when S and N are magnetized on the inner circumference of the billet, a strong magnetic force is obtained.

Example FIG. 1 shows a cross section of the billet before compression processing as seen from the axial direction of the billet, and FIG. 4 shows a cross section as seen from the front direction thereof, where 1 is made of an alloy for Mn-Al-C magnets. It is a cylindrical billet. A punch 2 includes a first compression surface 2a that compresses the billet 1 by axially pressing it and a protrusion 2b that protrudes inward from the center of the first compression surface 2a. And the first compression surface 2a has an inclination (α) that approaches the end of the billet 1 from its outer peripheral portion toward its inner peripheral portion, and the outer surface of the protruding portion 2b is uneven. It has 2 compression surfaces 2c. Reference numeral 4 is a mold for restraining the outer peripheral surface of the billet 1. FIG. 2 shows a state after the compression processing in which the punch 2 is moved to the punch 3 side. As shown in FIG. 2, the inner diameter of the cylindrical billet 1 becomes smaller as the compression process progresses, and a part of the inner peripheral surface comes into contact with the second compression surface 2c of the punch 2. As the compression processing is further advanced, the inner peripheral surface of the billet 1 comes into contact with the surface of the punch 2 substantially as shown in FIG. 2, while the outer peripheral surface comes into contact with the inner surface of the die 4. . It is not necessary to perform compression processing to the state shown in FIG. 2, and after a part of the inner peripheral surface of the billet 1 contacts the second compression surface 2c of the punch 2, the compression processing ends at an appropriate time. You may. In other words, irregularities may be formed on the inner peripheral surface of the billet 1. In this case, the minimum inner diameter of the billet 1 before compression processing is the size in contact with the convex portion on the surface of the punch 2. In this case, before the compression processing, the compression processing is performed with a part of the inner peripheral surface of the billet 1 already constrained by the surface of the punch 2.

As described above, since the second compression surface 2c of the punch 2 has irregularities, the billet 1 has irregularities formed on its inner peripheral surface after compression processing. In the compression processing process, the portion where the inner peripheral surface is constrained earliest (the concave portion of the inner peripheral surface of the billet 1 after processing) is the portion where the easy magnetization direction array is formed in the circumferential direction, and finally the inner peripheral surface is constrained. The portion where the inner peripheral surface is not constrained to the end (the convex portion of the inner peripheral surface of the billet 1 after processing, the portion closest to the center) is a portion where the easy magnetization direction array is formed in the radial direction. The direction of easy magnetization in the middle portion is a portion that sequentially changes from the circumferential direction to the radial direction. In other words, in the direction along the curved surface of the concave portion of the inner peripheral surface of the billet 1 formed by the convex portion of the second compression surface 2c of the punch 2 in FIG. Gradually changes continuously from the inner peripheral portion of the billet 1 (however, FIG. 5 shows the one for 8-pole magnetization). Therefore, the number of the uneven portions may be determined depending on how many poles are magnetized in the inner circumference magnetization. In Fig. 1, since there are 6 convex portions on the inner peripheral surface of the billet 1 after processing, the magnet has an anisotropic structure suitable for 6-pole magnetization, and the portion corresponding to the convex portion after processing is the inner peripheral surface. It becomes the pole part in magnetization.

As described in the above example, in the present invention, when the billet 1 is compressed in the axial direction, the inner peripheral surface of the billet 1 is molded and compressed so that the inner peripheral surface becomes uneven, so that the inner peripheral is magnetized. In this case, a magnet having an anisotropic structure that exhibits high magnetic properties is obtained.

Note that the billet 1 is designed such that the compression strain in the inner peripheral portion thereof becomes larger than the compression strain in the outer peripheral portion due to the axial compression, which will be described below with reference to FIG. Fourth
The figure shows a cross section in a state before processing as seen from the direction perpendicular to FIG. 1 is a billet, 2 and 3 are punches, and 4 is a mold.
As shown in FIG. 4, the first compression surfaces 2a and 3a of the punch 2 and the punch 3 which come into contact with the ends of the billet 1 extend from the outer peripheral portion toward the inner peripheral portion toward the end portion of the billet 1 as described above. It is a slope approaching. By using the punch 2 and the punch 3 to pressurize the billet 1 in the axial direction, the billet 1 is compressed in the axial direction. The height of the inner peripheral portion of the billet 1 after compression processing is lower than the height of the outer peripheral portion.
In other words, the compression processing is applied in the axial direction of the billet 1 so that the compression strain of the inner peripheral portion of the billet 1 becomes larger than the compression strain of the outer peripheral portion. Compressive strain refers to strain in the axial direction of the billet 1.

As described above, in this embodiment, manganese-aluminum-
When the hollow body billet 1 made of a carbon magnet alloy is axially compressed by the punches 2 and 3, the first compression surface 2a of the punch 2 has an end portion of the billet 1 from the outer peripheral portion toward the inner peripheral portion. Since the billet 1 has an inclination closer to, the compression strain of the inner peripheral portion of the billet 1 becomes larger than that of the outer peripheral portion thereof, and the billet 1 is compressed by the first compression surface 2a in the axial direction. The inner peripheral surface comes into pressure contact with the second compression surface 2c of the protruding portion 2b of the punch 2 and receives a compressive force. As a result, the inner peripheral portion of the compressed billet is easily magnetized in a substantially semicircular shape. The directional arrangement is easily formed by one-time compression, and when S and N are magnetized on the outer circumference of the billet 1, a strong magnetic force is obtained.

Regarding the temperature range in which compression processing as described above is possible,
Although it was in the temperature range of 530 to 830 ° C, the magnetic properties deteriorated considerably at a temperature exceeding 780 ° C. A more desirable temperature range was 560 to 760 ° C.

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

In the composition, 69.4% Mn, 29.3% Al, 0.5% C, 0.7%
Ni and 0.1% Ti were melted and cast to prepare a billet 1 having an outer diameter of 30 mm, an inner diameter of 24 mm and a length of 20 mm. This billet 1 1100
The temperature was maintained at 600C for 2 hours, air cooled to 600 ° C, maintained at 600 ° C for 30 minutes, and then cooled to room temperature. Next, FIG. 3 and FIG.
Using the punches 2 and 3 and the die 4 shown in the figure, compression processing was performed at a temperature of 680 ° C. through a lubricant until the voids in the die 4 were almost eliminated. In addition, in FIG. 3, (inner diameter of mold 4) Dk = 30 mm, X _A = 8 mm, (radius of convex portion of punch 2) R
_S = 2.5 mm, punch diameter D _P = 16 mm, and there are eight convex portions on the surface of the punch 2. In that case, there are eight recesses in the punch, and the punch can be moved in the vertical direction in FIG. Using such punches 2 and 3 and the die 4, compression processing was performed until the cavity of the die 4 was almost eliminated.

After cutting the billet 1 after processing to an inner diameter of 20 mm, 8
The inner circumference of the pole was magnetized. For the magnetization, an oil condenser of 2000 μF was used and pulsed at 1500 V. The surface magnetic flux density on the inner peripheral surface was measured with a Hall element.

For comparison, Mn, Al, C, Ni and Ti having the above-described composition were melt-cast and a cylindrical billet 1 having a diameter of 24 mm and a length of 20 mm was produced and subjected to the same heat treatment as described above. 680 ℃ for this billet 1
Free compression processing was performed at a temperature of up to 10 mm in the axial direction of the cylinder. The billet 1 after processing was cut in the same manner as described above, magnetized, 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 this example was about 1.7 times that of the magnet manufactured for comparison.

In the magnet obtained by the method of the present invention obtained in this example, as a result of the magnetic torque measurement, as described above, the easy magnetization direction array was continuously changed from the radial direction to the circumferential direction along the surface of the recess. confirmed.

As for the composition of the Mn-Al-C system alloy for magnets, only the quaternary system of Ni addition and the quaternary system of Ni and Ti additions have been shown above, but the basic composition of the Mn-Al-C system alloy magnet is shown. Although a slight difference was found in the magnetic characteristics of the magnet after plastic working in the ternary system or in the known multi-element system containing additive elements other than the above, the magnetic properties as described above were obtained by the method according to the conventional technique. The improvement was recognized.

As described above, according to the present invention, manganese-aluminum-
When a hollow billet made of a carbon-based magnet alloy is axially compressed by a punch, the first compression surface of the punch becomes
Since the billet has an inclination that approaches the end of the billet from the outer peripheral portion toward the inner peripheral portion, the compressive strain of the inner peripheral portion of the billet is larger than the compressive strain of the outer peripheral portion, and the billet axis due to the first compression surface is increased. By the compression in the direction, the inner peripheral surface of the billet comes into pressure contact with the second compression surface of the protruding portion of the punch and receives a compressive force, and as a result, the inner peripheral portion of the billet after compression is substantially A semi-circular easy magnetization direction array is easily formed by one compression, and when S and N are magnetized on the inner circumference of the billet, strong magnetic force is obtained.

[Brief description of drawings]

1 to 3 are plan sectional views of punches and molds used in the embodiments of the present invention, FIG. 4 is a front sectional view thereof, and FIG. 5 is a magnet for inner circumferential multipole magnetization of a cylindrical magnet. It is a figure which shows a road typically. 1 ... Billet, 2,3 ... Punch, 2a ... First compression surface, 2c ... Second compression surface, 4 ... Mold, .alpha .... Inclination angle.

Claims (3)

[Claims] 1. A hollow body-shaped billet made of an alloy for manganese-aluminum-carbon magnets is structured such that the punch is axially pressed and compressed at a temperature of 530 to 830 ° C., and the punch has the billet. 1st axial compression from the end
Of the first compression surface and a projecting portion projecting inwardly of the billet from the central portion of the first compression surface, wherein the first compression surface is
The billet is inclined from the outer peripheral portion toward the inner peripheral portion toward the end portion of the billet, and the billet is compressed by the inclined first compression surface so that the compressive strain of the inner peripheral portion is larger than that of the outer peripheral portion. And the protrusion has an uneven second compression surface on its outer surface, and the second compression surface molds the inner peripheral surface of the billet unevenly. Manufacturing method of carbon alloy magnets. 2. The method for producing a manganese-aluminum-carbon alloy magnet according to claim 1, wherein the compression processing by punching is performed with the outer periphery of the billet being constrained. 3. The method for producing a manganese-aluminum-carbon alloy magnet according to claim 1, wherein the compression processing by punching is performed with a part of the inner circumference of the billet being constrained.