JPH0663071B2 - 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.

2. Description of the Related Art Mn-Al-C alloy magnets are mainly composed of a face-centered tetragonal structure (τ phase, L ₀ -type ordered lattice) that is a ferromagnetic phase, and have a C
It is known that ternary alloy magnets containing as an essential constituent element, containing no additional elements other than impurities, and quaternary or more multi-component alloy magnets containing a small amount of additional elements are collectively referred to.

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 both in 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 outer circumference or the inner circumference as shown in the figure, the ideal semi-circular B line which is the ideal easy magnetization direction array 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 to a substantially semi-circular shape as shown in FIG. 6 of the present application, and thereafter magnetizing the inner periphery. I was trying to do the 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, an object of the present invention is to make it possible to easily obtain a substantially semi-circular array of easy magnetization directions in the case of magnetizing S and N on the outer peripheral portion of the billet.

Means for Solving the Problems To achieve this object, the present invention provides a hollow body-shaped billet made of a polyaniline manganese-aluminum-carbon alloy magnet that is roughly anisotropy and has an outer mold. And the first compression surface for compressing the billet end portion of the punch has a slope approaching the billet end portion from the inner peripheral portion toward the outer peripheral portion. The inclined first compression surface compresses the billet at a temperature of 530 to 830 ° C. so that the compression strain of the outer periphery is larger than the compression strain of the inner periphery, and the first compression is further performed. The outer peripheral surface of the billet that expands in the outer peripheral direction by the compression processing by the surface is formed into an uneven shape by the uneven second compression surface formed on the inner peripheral surface of the outer mold.

With the above configuration, the billet is subjected to the first compression of the punch in a state where the outer die is arranged on the outer periphery of the hollow body billet made of the pre-anisotropic polycrystalline manganese-aluminum-carbon magnet alloy. When compressed axially by the surface, the first compression surface of the punch has an inclination that approaches the billet from the inner peripheral portion toward the outer peripheral portion, so that the billet has a compressive strain of the outer peripheral portion that is the compressive strain of the inner peripheral portion. Further, the outer peripheral portion of this billet is formed into an uneven shape by the uneven second compression surface formed on the inner peripheral surface of the outer die, and as a result, the outer peripheral portion of the billet after compression is substantially A semicircular easy magnetization direction array is easily formed by one-time compression, and a strong magnetic force can be obtained by magnetizing S and N on the outer circumference of the billet.

Example First, an example of molding the outer peripheral surface of the billet into a concavo-convex shape by compression processing will be described with reference to FIG. 1 and 5 are cross-sectional views of the state before compression as seen from the axial direction of the billet, and 1 is a cylindrical billet made of a pre-anisotropic polycrystalline Mn-Al-C alloy magnet. , 2 and 3 are punches, which are compression surfaces 2a and 3a for compressing the ends of the respective billets 1.
Has an inclination that approaches the end of the billet 1 from the inner peripheral portion toward the outer peripheral portion. A protrusion 2b is formed from the center of the compression surface 2a of the punch 3 into the billet 1. This prevents the billet 1 from spreading to the center when the billet 1 is compression-molded. The outer die 4 is located on the outer circumference of the billet 1 and has an uneven inner surface.
The compression surface 4a is formed. FIG. 2 shows the state after compression processing. As shown in FIG. 2, the cylindrical billet 1 has a diameter that increases with the progress of compression processing by the first compression surfaces 2a, 3a of the punches 2, 3, and a part of the outer peripheral surface is the outer die. The inner peripheral surface of the billet 1 comes into contact with the convex portion of the second compression surface 4a, and the compression processing is further advanced so that the outer peripheral surface of the billet 1 is almost inside the outer mold 4 as shown in FIG. The inner peripheral surface of the billet 1 contacts the surface of the protruding portion 2b of the punch 2 while contacting the concave portion of the peripheral surface. It is not necessary to perform compression processing to the state shown in FIG. 2, and after a part of the outer peripheral surface of the billet 1 contacts the inner surface of the outer die 4, the compression processing may be finished at an appropriate time. In other words, irregularities may be formed on the outer peripheral surface of the billet 1.

In this case, the maximum outer diameter of the billet 1 before compression processing is the size in contact with the convex portion of the second compression surface 4a of the inner peripheral surface of the outer die 4. 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 4. An example of this case is shown in FIG. Third
The figure is a cross section similar to that of FIG. 1, showing the state before compression processing. In the example shown in FIG. 3, the inner peripheral surface of the billet 1 is also in contact with the surface of the protruding portion 2b of the punch 2 before the compression processing.

Thus, the second compression surface 4a on the inner peripheral surface of the outer die 4 has irregularities, so that the billet 1 has irregularities formed on the outer peripheral surface after compression processing. In the compression processing process, the portion where the outer peripheral surface is restrained the earliest (recessed portion of the outer peripheral surface of the billet 1 after processing) becomes the portion having the easy magnetization direction array in the circumferential direction as shown by the line B in FIG. The portion where the surface is constrained or the portion where the outer peripheral surface is not constrained to the end (the convex portion of the outer peripheral surface of the billet 1 after processing) is a portion having the easy magnetization direction array 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 FIG. 1, the easy magnetization direction gradually and continuously changes from the outer peripheral portion of the billet 1 in the direction along the curved surface of the concave portion of the outer peripheral surface of the billet 1 formed by the convex portion on the inner surface of the outer mold 4. Therefore, the number of the uneven portions may be determined depending on how many poles are magnetized in the outer circumference magnetization. In FIG. 1, since there are six protrusions on the outer peripheral surface of the billet 1 after processing, the magnet has an anisotropic structure suitable for 6-pole magnetization,
The portion corresponding to the convex portion after processing becomes the pole portion in the outer peripheral magnetization.

As described in the above-mentioned example, according to the present invention, when the billet 1 is compressed in the axial direction, the billet 1 is molded and compressed so that the outer peripheral surface of the billet 1 becomes uneven. It is intended to obtain a magnet having an anisotropic structure that exhibits high magnetic properties when magnetized.

Further, in this embodiment, compression processing is performed so that the compression strain of the outer peripheral portion of the billet 1 is larger than the compression strain of the inner peripheral portion, which will be described with reference to FIG. FIG. 5 shows a cross section in a state before processing viewed from the direction perpendicular to FIG. Fifth
As shown, a billet 1 of punch 2 and punch 3
The first compression surfaces 2a, 3a contacting the ends of the billet 1 are not flat but inclined surfaces approaching the ends of the billet 1 from the inner peripheral portion toward the outer peripheral portion. By using the punch 2 and the punch 3 to process the billet 1 in the axial direction, the billet 1 is compressed in the axial direction. The height of the outer peripheral portion of the billet 1 after compression processing is lower than the height of the inner peripheral portion. That is,
The billet 1 is subjected to compression processing in the axial direction so that the compressive strain of the outer peripheral portion of the billet 1 becomes larger than the compressive strain of the inner peripheral portion. Compressive strain refers to strain in the axial direction of the billet 1.

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

69.4% Mn, 29.3% Al, 0.5% C, 0.7%
Ni and 0.1% Ti are melt-cast, diameter 50mm, length 40mm
The cylindrical billet 1 was manufactured. 1100 ° C for this billet 1
After holding for 2 hours at 600 ° C., it was air-cooled to 600 ° C., held at 600 ° C. for 30 minutes, and then allowed to cool to room temperature.

Next, pressure processing was performed at a temperature of 720 ° C. via a lubricant. The billet 1 after pressing had a diameter of 32 mm and a length of 98 mm. The pressing rod is cut and cut to give an outside diameter of 24
A billet 1 having a diameter of 18 mm, an inner diameter of 18 mm and a length of 20 mm was produced. This billet 1 was subjected to compression processing at a temperature of 680 ° C. through a lubricant using the mold shown in FIGS. 4 and 5. Processing was performed until the cavity in the mold was almost eliminated.
Note that α in Fig. 5 is 10 °, (inner diameter of outer diameter 4) Dk = 30 mm, X
_A = 15 mm, (radius of the convex portion of the outer die 4) Rs = 3 mm, the diameter of the protrusion 2b of the punch is 18 mm, and there are eight convex portions on the inner surface of the outer die 4.

Next, after billet 1 was cut to an outer diameter of 27 mm, it was magnetized on the outer periphery of 8 poles, and the surface magnetic flux density was measured.

For comparison, the extruded rod described above was cut and cut to produce a cylindrical billet 1 having a diameter of 24 mm and a length of 20 mm. The 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 up to 10 mm. 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.

Effects of the Invention As described above, according to the present invention, the billet of the punch is formed in a state in which the outer die is arranged on the outer periphery of the hollow body billet made of a pre-anisotropic polycrystalline manganese-aluminum-carbon magnet alloy. The first compression surface of the punch is axially compressed by the first compression surface, and the first compression surface of the punch has an inclination that approaches the billet from the inner peripheral portion toward the outer peripheral portion. It becomes larger than the compressive strain of the inner peripheral part, and the outer peripheral part of this billet is molded into an uneven shape by the uneven second compression surface formed on the inner peripheral surface of the outer mold, and as a result, the billet after compression is On the outer periphery,
A substantially semi-circular array of easy magnetization directions is easily formed by one compression, and a strong magnetic force can be obtained by magnetizing S and N on the outer circumference of the billet.

[Brief description of drawings]

1 to 5 are cross-sectional views of a mold part used in an embodiment of the present invention, and FIG. 6 is a diagram schematically showing a magnetic path by outer peripheral multipole magnetization in a cylindrical magnet. 1 ... Billet, 2, 3 ... Punch, 2a, 3a ... First compression surface, 4 ... Outer mold, 4a ... Second compression surface, .alpha.

Claims (2)

[Claims] 1. Pre-anisotropic polycrystalline manganese-
An outer die is arranged on the outer circumference of a hollow-body-shaped billet made of an aluminum-carbon alloy magnet, and the end is compressed by a punch. The first compression surface for compressing the billet end of the punch has an inner circumference. Section has a slope approaching the end of the billet toward the outer periphery, and the first compression surface with the slope causes the billet to have compressive strain of the outer periphery at the temperature of 530 to 830 ° C. Of the billet, and the outer peripheral surface of the billet that expands in the outer peripheral direction by the compression processing by the first compression surface is formed into the inner peripheral surface of the outer die to form the second compression A method for manufacturing a manganese-aluminum-carbon alloy magnet, which is formed into an uneven shape by a surface. 2. The compression processing by the first compression surface of the punch comprises:
The method for producing a manganese-aluminum-carbon alloy magnet according to claim (1), which is carried out with a part of the outer periphery of the billet being constrained by the second compression surface of the outer die.