JPH0663068B2 - 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, the Mn-Al-C alloy magnet is mainly a face-centered tetragonal crystal (τ phase, LI ₀ type ordered lattice) that is a ferromagnetic phase.
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 at both the inner and outer peripheral portions 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 the magnetizing of N, the inner peripheral portion of the compressed billet is compressed again to bring the easy magnetization direction array to a substantially semicircular shape as shown by line B in FIG. 6 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, 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 hollow body-shaped billet made of an aluminum-carbon magnet alloy is billeted from the inner peripheral portion to the outer peripheral portion at a temperature of 530 to 830 ° C., with at least a part of the outer peripheral portion and the inner peripheral portion of the billet being free. Is compressed in the axial direction by a punch having a compression surface having an inclination approaching the end of the billet, so that the compression strain of the outer peripheral portion of the billet is greater than the compression strain of the inner peripheral portion. .

With the above configuration, when the outer periphery of the hollow body billet made of the alloy for manganese-aluminum-carbon magnets is axially compressed by the punch, the compression surface of the punch becomes the billet from the inner peripheral portion toward the outer peripheral portion. Since the billet has an approaching inclination, the compressive 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 semi-circular magnetic easy direction array is once formed on the outer peripheral portion of the billet after compression. It is easily formed by the compression of S and N, and when S and N are magnetized on the outer periphery of the billet, a strong magnetic force is obtained.

Example FIG. 1 shows a cross section before processing. 1 is billet, 2,
3 is a punch. As shown in FIG. 1, the compression surfaces 2a and 3a of the punch 2 and the punch 3 which come into contact with the billet 1 are inclined so as to approach the ends of the billet 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 1 is compressed in the axial direction to the state shown in FIG. Second
As shown in the figure, the height of the outer peripheral portion of the billet 1 after processing is lower 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.

That is, in this embodiment, when the outer circumference of the hollow body billet 1 made of an alloy for manganese-aluminum-carbon magnets is axially compressed by the punches 2 and 3, the compression surfaces 2a and 3a of the punches 2 and 3 are Since the billet 1 has an inclination that approaches the billet 1 from the peripheral portion toward the outer peripheral portion, the compressive strain of the outer peripheral portion of the billet 1 becomes larger than the compressive strain of the inner peripheral portion, and as a result, the outer peripheral portion of the billet 1 after compression is Is easily formed by a single compression, as shown by the line B in FIG. 6, and a strong magnetic force can be obtained by magnetizing S and N on the outer periphery of the billet 1. It will be obtained.

3 to 5 show another embodiment, and FIG. 3 shows a cross section before processing. 1 is a billet, 2 and 3 are punches, and 4 is an outer mold. As shown in FIG. 3, the difference from the above-mentioned embodiment is that the outer mold 4 is used. This punch 2,3
By pressing the billet 1 in the axial direction using, the billet 1 is compressed in the axial direction to the state shown in FIG. 4, and when further compressed, it becomes as shown in FIG. 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, also in this case, the compression processing is performed 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 periphery.

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.

Example 1 (Fig. 1) 69.4% Mn, 29.3% Al, 0.5% C, 0.7%
Ni and 0.1% Ti are melt-cast, outer diameter 30mm, inner diameter 16m
A cylindrical billet 1 having m and a length of 25 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, using a die made of punches 2 and 3 as shown in FIG. 1 through a lubricant, compression processing was performed at a temperature of 680 ° C. until the inner peripheral length of the billet 1 was 15 mm. went. In FIG. 1, the inclination angle (α) of the punch end face is 10 °.

After machining the billet 1 after processing to an outer diameter of 40 mm, outer circumference was magnetized with 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 prepare a cylindrical billet 1 having an outer diameter of 30 mm, an inner diameter of 16 mm and a length of 25 mm, and the same heat treatment as described above was performed. Next, a punch having a flat compression surface was used to perform compression processing up to 15 mm in length through a lubricant.
Further, after cutting the same as the above, it was magnetized 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.

Concrete Example (Fig. 3) Mn, Al, C and Ni having the same composition as in Concrete Example 1 were melt cast, and a cylindrical billet 1 having an outer diameter of 30 mm, an inner diameter of 16 mm and a length of 25 mm was prepared.
Was prepared and subjected to the same heat treatment as in Example 1. Next, using a die having punches 2, 3 and an outer diameter 4 as shown in FIG. 3 through a lubricant, the outer and inner circumferences of the billet 1 were made free, and the temperature of 680 ° C. Then, the outer peripheral portion of the billet 1 was compressed to a length of 13.3 mm. Punch 2,3
The inclination angle (α) of the end face is 10 °, and the inner diameter of the outer mold 4 is 34 mm.

The billet 1 that had been subjected to this compression processing was cut into an outer diameter of 33 mm, and then magnetized with 24 poles in the same manner as in Example 1. The surface magnetic flux density was measured and compared with a magnet manufactured for comparison.

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, the present invention compresses the outer circumference of a hollow body billet made of an alloy for manganese-aluminum-carbon magnets in the axial direction by a punch, in which the compression surface of the punch is from the inner peripheral portion to the outer periphery. Since the billet has an inclination that approaches the billet, the compression strain of the inner circumference of the billet is larger than that of the inner circumference, and as a result, the outer circumference of the billet after compression has a substantially semicircular shape. The easy magnetization direction array of is easily formed by one-time compression, and when S and N are magnetized on the outer periphery of the billet, a strong magnetic force is obtained.

[Brief description of drawings]

1 to 5 are cross-sectional views of an embodiment of the present invention, and FIG. 6 is a plan view showing an easy magnetization direction array. 1 ... Billet, 2,3 ... Punch, 4 ... Outer mold.

Claims (1)

[Claims] 1. A hollow body-shaped billet made of an alloy for manganese-aluminum-carbon magnets, at a temperature of 530 to 830 ° C., with at least part of the outer and inner circumferences of the billet being free, From the axial direction to the outer circumference of the billet, a punch having a compression surface with a slope that approaches the end of the billet causes the compression strain in the outer circumference of the billet to be greater than the compression strain in the inner circumference. A method for producing a manganese-aluminum-carbon alloy magnet, which is subjected to compression processing.