JPH0663074B2 - 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 (tau 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, since the billet is subjected to substantially the same compressive strain both in the billet and the outer peripheral portion, for example, this compression causes the easy magnetization direction arrangement to be as shown in FIG. It becomes a substantially straight line in the radial direction like the line A.

Therefore, in this state, for example,
Even if you try to magnetize S and N, the magnetization easy direction arrangement is too different from the ideal semi-circular B line, which is the ideal easy magnetization direction arrangement in that case. No strong magnetic force was obtained.

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 in FIG. 3 of the present application, and then 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 easy magnetization direction array in the case where S and N are magnetized on the inner peripheral portion of the billet.

In order to achieve this object, the present invention provides manganese-
A hollow-body billet made of an aluminum-carbon magnet alloy is punched at a temperature of 530 to 830 ° C. with the outer periphery of the billet constrained by an outer mold, and at least a part of the inner periphery is free. The compression surface of the punch is provided with an inclination that approaches the end of the billet from the outer peripheral surface toward the inner peripheral surface so that the compression strain of the inner peripheral portion of the billet is The compression processing is performed in the axial direction of the billet so as to be larger than the compression strain of the part.

With the above configuration, in the state where the outer periphery of the hollow body billet made of the alloy for manganese-aluminum-carbon magnets is constrained by the outer mold, when this billet is axially compressed by the punch, the compression surface of the punch is Since the billet has an inclination that approaches the end of the billet from the outer circumference to the inner circumference, the compression strain of the inner circumference of the billet is larger than that of the outer circumference, and as a result, the inner circumference of the billet after compression is increased. A semi-circular easy magnetizing direction array is easily formed in the part by one-time compression.
By magnetizing, a strong magnetic force will be obtained.

Example FIG. 1 shows a cross section before processing. 1 is billet, 2,
3 is a punch and 4 is an outer type. As shown in FIG. 1, the compression surface 2 in contact with the billet 1 of the punch 2 and punch 3
The a and 3a have an inclination that approaches the end of the billet 1 from the outer peripheral portion toward the inner peripheral portion. 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 to the state shown in FIG. As shown in FIG. 2, the height of the inner peripheral portion of the billet 1 after compression processing is lower than the height of the outer peripheral portion thereof. 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.

That is, in this embodiment, the billet 1 is punched by the punch 2, while the outer periphery of the hollow body billet 1 made of an alloy for manganese-aluminum-carbon magnets is constrained by the outer die 4.
It is compressed in the axial direction by 3, and the compression surface 2 of the punch 2, 3
Since a and 3a have an inclination that approaches the end of the billet 1 from the outer peripheral portion toward the inner peripheral portion, the compressive strain of the inner peripheral portion of the billet 1 becomes larger than the compressive strain of the outer peripheral portion, and as a result, In the inner peripheral portion of the billet 1 after compression, a substantially semicircular easy magnetization direction array is easily formed by one compression as shown by line B in FIG. By magnetizing, a strong magnetic force will be obtained.

The compression process as described above could be performed in the temperature range of 530 to 830 ° C, but the magnetic properties were considerably deteriorated at the temperature exceeding 780 ° C. A more desirable temperature range is 560
It was ~ 760 ° C.

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, outer diameter 30mm, inner diameter 20m
A cylindrical billet 1 having m and a length of 20 mm was produced. Hold this billet 1 at 1100 ° C for 2 hours, air cool to 600 ° C, and
After holding at 00 ° C. for 30 minutes, a heat treatment of allowing to cool to room temperature was performed.

Next, the outer peripheral surface of the billet 1 was constrained with an outer die 4 as shown in FIG. 1 through a lubricant, and the inner periphery was left free, and the cylindrical billet was heated at a temperature of 680 ° C. Compression processing was performed as shown in FIG. 2 until the length of the outer peripheral portion of 1 became 13.3 mm. In FIG. 1, the punch end face has an inclination angle (α) of 20 ° and the outer die 4 has an inner diameter of 30 mm.

The billet 1 after processing was cut into an inner diameter of 18 mm, and inner poles were magnetized with 18 poles, and the surface magnetic flux density on the inner peripheral surface was measured.

For comparison, Mn, A with the same composition as the composition described above
l, C, Ni and Ti were melted and cast to form a cylindrical billet having an outer diameter of 30 mm, an inner diameter of 20 mm and a length of 20 mm. The billet was compression-processed with a punch having a flat compression surface. The length of the billet after processing was 13.3 mm. Further, it was cut and magnetized in the same manner as above, 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 this example was about 1.2 times that of the magnet produced for comparison.

EFFECTS OF THE INVENTION As described above, according to the present invention, a hollow body billet made of a manganese-aluminum-carbon magnet alloy is compressed in the axial direction by a punch in a state where the outer periphery of the billet is constrained by an outer die. Since the compression surface of has an inclination that approaches the end of the billet from the outer periphery toward the inner periphery,
The compressive strain of the inner circumference of the billet becomes larger than the compressive strain of the outer circumference, and as a result, a semi-circular easy magnetization direction array is easily formed by one compression on the inner circumference of the billet after compression. Moreover, when S and N are magnetized on the inner circumference of the billet, a strong magnetic force can be obtained.

[Brief description of drawings]

1 and 2 are cross-sectional views showing an example of the compression processing of the present invention, and FIG. 3 is a plan view showing the arrangement in the easy magnetization direction. 1 ... Billet, 2,3 ... Punch, 4 ... Outer mold.

Claims (1)

[Claims] 1. A hollow-body billet made of an alloy for manganese-aluminum-carbon magnets, at a temperature of 530 to 830 ° C., with the outer periphery of the billet constrained by an outer mold, and at least a part of the inner periphery. In a free state, the punch is configured to compress in the axial direction, and the compression surface of the punch is
By providing an inclination approaching the end of the billet from the outer peripheral surface toward the inner peripheral surface, the billet is compressed in the axial direction so that the compressive strain of the inner peripheral portion is larger than the compressive strain of the outer peripheral portion. Manganese-Aluminum-
Manufacturing method of carbon alloy magnets. Construction method.