JPH0663066B2 - 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. In addition, Mn-Al- formed using this alloy
C alloy magnet is composed of mainly face-centered tetragonal (tau phase, L1 ₀ type ordered lattice) is a ferromagnetic phase of tissue.

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, even if it is attempted to magnetize S and N on the outer circumference or the inner circumference as shown in the same figure, the ideal semi-circular B line which is the ideal easy magnetization direction array in that case is too much. However, since the arrangement in 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 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 array of easy magnetization directions in the case of magnetizing S and N on the outer peripheral portion of the billet.

In order to achieve this object, the present invention provides manganese-
A billet in the form of a hollow body made of an aluminum-carbon magnet alloy is held at a temperature of 530 to 830 ° C. with the outer periphery of the billet being constrained by an outer mold, and its compression surface extends from the inner periphery to the outer periphery. With a punch having an inclination approaching to, the billet is compressed in the axial direction so that the compressive strain of the outer peripheral portion of the billet is larger than the compressive strain of the inner peripheral portion.

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 approaching the billet from the inner peripheral portion toward the outer peripheral portion, the compression strain of the outer peripheral portion of the billet is larger than the compressive strain of the inner peripheral portion, and as a result, the outer peripheral portion of the billet after compression is
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.

Example FIG. 1 shows a cross section before processing. 1 is billet, 2,
3 is a punch and 4 is an outer type. Punch 2 and punch 3
The compression surface that contacts the billet 1 is not a flat surface but an inclined surface that approaches the billet 1 from the inner peripheral portion toward the outer peripheral portion. By using the punch 2 and the punch 3 to pressurize the billet 1 in the axial direction, the billet is compressed in the axial direction to the state shown in FIG. As shown in FIG. 2, the height of the outer peripheral portion of the billet 1 after compression processing is smaller than the height of the inner peripheral portion. That is, the compression processing is applied in the axial direction of the billet 1 so that the compression strain of the outer peripheral portion of the billet 1 becomes larger than the compression strain of the inner peripheral portion. Compressive strain refers to strain in the axial direction of the billet 1.

Thus, the arrangement of the easy magnetizing directions in the radial direction of the magnets can be freely controlled.

The temperature range in which compression processing as described above is possible is 530 to 830.
In the temperature range of ℃, over 780 ℃, the magnetic properties deteriorated considerably. More desirable temperature range is 560-7
It was 60 ° C.

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

Example 1 (FIGS. 1 and 2) 69.4% Mn, 29.3% Al, 0.5% C, 0.7% in the composition
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. The billet 1 was held at 1100 ° C. for 2 hours, and then heat-treated to cool to room temperature. Next, through a lubricant, a die consisting of punches 2, 3 and an outer die 4 was used to restrain the outer peripheral surface of the cylindrical billet 1, and the inner periphery was made free, and at a temperature of 680 ° C. The cylindrical billet 1 was compressed to a peripheral length of 13.3 mm. In FIG. 1, the punch end face has an inclination angle α of 20 ° C., and the outer die 4 has an inner diameter of 30 mm.

The billet 1 after processing was cut into an outer diameter of 29 mm, subjected to outer peripheral magnetization of 24 poles, and the surface magnetic flux density 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. This billet was subjected to the same heat treatment as above. Next, compression processing was performed through a lubricant using a punch having a flat compression surface and a die having an outer diameter of 4. The billet 1 after processing had a length of 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.

That is, as in this embodiment, manganese-aluminum-
With the outer periphery of the hollow body-shaped billet 1 made of an alloy for carbon-based magnets constrained by the outer mold 4, the billet 1 is punched by punches 2, 3
When compressed in the axial direction by, the compression surfaces of the punches 2, 3 have an inclination that approaches the billet 1 from the inner peripheral portion toward the outer peripheral portion, so that the billet 1 has a compressive strain in the outer peripheral portion that compresses the inner peripheral portion. The strain becomes larger than the strain, and as a result, a substantially semicircular easy magnetization direction array is easily formed on the outer peripheral portion of the billet 1 after compression as shown by line B in FIG. When S and N are magnetized on the outer circumference of, the strong magnetic force will be obtained.

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. Regarding the ternary system, a slight difference was observed in the magnetic characteristics of the magnet after compression processing, but the above-mentioned improvement in magnetic characteristics was recognized by the known compression processing method.

As described above, according to the present invention, when the outer periphery of the hollow body billet made of the alloy for manganese-aluminum-carbon magnets is constrained by the outer die, when this billet is axially compressed by the punch, Since the compression surface of the punch has an inclination that approaches the billet from the inner peripheral portion toward the outer peripheral portion, the compression strain of the outer peripheral portion of the billet is larger than that of the inner peripheral portion, and as a result, the billet after compression is An approximately semi-circular easy magnetization direction array is easily formed on the outer periphery of the single compression by one time.
When N is magnetized, a strong magnetic force will be obtained.

[Brief description of drawings]

1 and 2 are sectional views showing an example of the compression processing of the present invention. FIG. 3 is a plan view showing the arrangement of easy magnetization directions. 1 …… Billet, 2,3 …… Punch, 4 …… Outer mold, α ……
Tilt angle.

Claims (1)

[Claims] 1. A hollow body-shaped billet made of an alloy magnet for a manganese-aluminum-carbon magnet, at a temperature of 530 to 830 ° C., with the outer periphery of the billet being constrained by an outer die, the compression surface of which is By a punch having an inclination approaching the billet from the peripheral portion toward the outer peripheral portion, manganese-aluminum-compressed in the axial direction of the billet so that the compressive strain of the outer peripheral portion of the billet is larger than the compressive strain of the inner peripheral portion. Manufacturing method of carbon alloy magnets.