JPS6126205A - Manufacture of rare earth magnet - Google Patents

Abstract

PURPOSE:To prevent a variability of magnetic characteristics by filling a magnetic material including rare earth elements in a mold under a magnetic field which is parallel to a pressing direction to remove gaps among the powders and subsequently processing and shaping the material under the magnetic field parallel to the pressing direction. CONSTITUTION:The powder of the material of a magnet is put in a feeder 1 and it is enclosed air-tightly. A reticular filter 4 is arranged on a lower plane of the feeder to send the air for pressing. The feeder is driven into an outer frame 2 of a mold and is stopped above a punch 3 while a magnetic field is applied in parallel to the pressing direction. The air is injected into the feeder and the pressure is increased to spout the powder from holes of the filter 4. The feeder 1 is raised gradually to fill the powder to the regulated thickness. At this time, because the powder is orientated by the magnetic field till it reach the punch, the powder is spouted uniformly and a distribution of density also becomes uniform. After filling the powder, the feeder is removed and compression molding is done followed by sintering. At that time, a magnetic field in the pressing direction is not always necessary. By this constitution, the rare earth magnet having the uniform density of a molded body and magnetic characteristics can be obtained.

Description

[Detailed description of the invention] 〔Technical field〕 The present invention relates to a method for manufacturing rare earth magnets.

(Background technology) Rare earth magnets, especially rare earth cobalt magnets, are known to be high-performance magnets with high b1 saturation magnetization and high coercive force. began to be adopted.

The general manufacturing method for rare earth magnets is as follows. Alloys containing rare earth elements such as samarium and cerium (mostly cobalt, as well as other elements and impurities added to improve properties).

) is crushed and pulverized. By press-molding this powder in a magnetic field, the powder (magnetic powder) is oriented in the axis of easy magnetization, and the compact is given magnetic anisotropy. next,
This molded body is 1) sintered at 60° C. to 1220° C., rapidly cooled, and then aged at around 800° C. for 5 to 10 hours and slowly cooled. In this way, a high performance rare earth magnet can be obtained.

By the way, the saturation magnetization of an anisotropic magnet is greatly influenced by the degree of orientation of the magnetic domains, that is, the degree of blending of the powder. In order to improve the degree of orientation of the powder, it is preferable that the powder be in a state where it can flow as easily as possible when a magnetic field is applied. When molding is performed in a magnetic field parallel to the pressing direction, first fill the mold filling section with the above powder, then lower the upper punch (also referred to as upper punch) to just above the powder, and press the powder while applying the magnetic field. Since it is molded, it becomes difficult for the powder to become oriented. In particular, when molding a thin plate-like object, a magnetic field is applied between the filled powder and the upper punch without leaving any space, making it difficult for the powder to become oriented.

Furthermore, when the powder is filled, many voids are created between the powders. As a result, the density of the molded product becomes non-uniform depending on the location, the magnetic properties also vary, and cracks are likely to occur when molding a thin plate-like product.

[Purpose of the invention]

An object of the present invention is to provide a method for manufacturing rare earth magnets that eliminates the above-mentioned drawbacks such as non-uniform density of compacts and variations in magnetic properties.

[Disclosure of the invention]

In order to achieve the above object, the present invention provides a method for manufacturing a rare earth magnet that includes a step of press-molding magnet material powder containing rare earth elements while applying a magnetic field in a direction parallel to the pressing direction. The gist of the method is to apply a magnetic field in a direction parallel to the pressurizing direction when filling the magnet. Hereinafter, one embodiment of the manufacturing method of the present invention will be described in detail with reference to the accompanying drawings.

The magnet material used in this invention is a powder (usually pulverized) of an alloy containing rare earth elements (often also containing cobalt, and also contains elemental impurities added to improve properties). ) is used. For molding, a press device with a magnetic field generating means is used so that the direction of pressure and the direction of the magnetic field are parallel. A feeder having the same cross-sectional shape as a punch (also called punch) is used to fill the powder.

As shown in FIG. 1(a), the powder of the magnetic material described above is placed in a feeder 1 and the feeder 1 is sealed. In addition, on the bottom surface of feeder 1,
As shown in FIG. 1(G), a mesh filter 4 is provided. Also, for feeder 1, arrow A
Air is fed into the feeder 1 and pressure can be applied as shown in the figure.

Next, as shown in Fig. 2, the feeder 1 is pushed into the mold outer frame 2 in the same way as pushing with an upper punch (not shown), and is stopped directly above the lower bunch 3, so that the feeder 1 is pressed in the pressing direction. Apply a magnetic field in parallel directions. Air is injected into the feeder to increase the pressure, and the powder is ejected from the holes in the mesh filter 4. The feeder 1 is gradually raised to fill the powder to a specified thickness. At this time, the powder is oriented by the magnetic field before it is scattered in the air and attached to the lower punch, so it is very likely to be oriented. Furthermore, since the powder is ejected almost uniformly over the entire surface, the density distribution is extremely small. After filling the powder, the feeder 1 is removed, the upper punch is lowered, and pressure molding (compression molding) is performed.

At this time, it is common to apply a magnetic field, but this does not necessarily have to be the case. The molded body thus obtained may be sintered according to a conventional manufacturing method.

Next, examples and comparative examples will be shown.

(Example 1) A feeder whose cross section perpendicular to the pressurizing direction has a ring shape with an outer diameter of 35φ and an inner diameter of 22φ is used, and the tips of the lower six parts have a diameter of 10 mm.
A hole (0,147mm) equivalent to 0 mesh is provided.

In this feeder, 5rn2 (Co
, Cu, Fe, Zr) 17 alloy powder is put in and sealed. As shown in FIG. 3, the tip of the feeder 1 is connected to the mold outer frame 2. It is fitted into the mold filling part consisting of the lower punch 3° and the core rod 5 by about 0.5 mm and left stationary. Then,
Air is injected into the feeder while applying a magnetic field of about 10'kOe in a direction parallel to the pressurizing direction, and the inside of the feeder is heated by about 1.5 kOe.
Maintain atmospheric pressure. Then, the powder is transferred to the hole 4 at the tip of the feeder.
' and fills the mold filling part. Filling is completed by ejecting for 1 minute, the feeder is removed, the upper punch is lowered, and pressure molding is performed while applying a magnetic field of about 20 kOe in a direction parallel to the pressing direction. The dimensions of the molded body are external diameter 35φ
It was ring-shaped with an inner diameter of 22φ and a thickness of 2fi. This molded body was heated to 1200°C.

A rare earth magnet was obtained by sintering for 1 hour.

(Comparative Example 1) Using the same magnetic material as in Example 1, powder was dropped into the same mold filling part using a feed shoe as shown in Fig. 4 without applying a magnetic field. It was molded and sintered.

In the manufacturing method of Comparative Example 1, the powder was filled in the conventional manner, and a thin plate ring shape as described above was obtained.

In contrast, in Example 1, which is the manufacturing method of this invention, in contrast, when molding a
The molding was completed with a yield of almost 100%. The rare earth magnets obtained in Example 1 and Comparative Example 1 were subjected to X-ray diffraction, and the degree of orientation was determined from the relative ratio of the peak intensity in the easy axis direction and the peak intensity in the hard axis direction. In Example 1, it was 95%.
In Comparative Example 1, the result was 80%. That is, if a magnetic field is applied in a direction parallel to the pressing direction during powder filling, the degree of orientation of the powder is significantly improved.

〔Effect of the invention〕

In the manufacturing method of this invention, when filling powder into the mold filling part,
A magnetic field is applied in a direction parallel to the direction of pressurization.

Therefore, according to this manufacturing method, the powder is oriented when the powder is in a good fluidity state, so a compact with a small density distribution and a good degree of orientation can be obtained. A rare earth magnet is obtained.

[Brief explanation of drawings]

Fig. 1 Ta) is a sectional view of the feeder seen from a direction perpendicular to the pressurizing direction, Fig. 1(b) is a mesh filter attached to the bottom surface of the feeder, and Fig. 2 is an implementation of the method of the present invention. FIG. 3 is a sectional view of another embodiment as seen from a direction perpendicular to the pressing direction, and FIG. 4 is a comparison view. Cross-sectional view seen from the direction perpendicular to the pressurizing direction in the example 1...Feeder 2...Mold outer frame 3...Lower punch 4.4'...Mesh-like filter 5...Core rod agent Patent Attorney Takehiko Matsumoto 9F
4 Rikensoho Seisho (0 Marty 9 September 25, 1988 Patent Application No. 146644 2, Name of Invention Method for Manufacturing Rare Earth Magnets 3, Relationship with the Amendment Person Case Patent Applicant Location 1048 Oaza Kadoma, Kadoma City, Osaka Prefecture Name (583) Matsushita Electric Works Co., Ltd. Representative I Taikan Kobayashi 4. No agent 6. Specification subject to amendment 7. Contents of amendment (1) Specification No. On page 4, line 14, it says “air”.
Correct it to "nitrogen gas." (2) On page 4, line 20 of the specification, the word "air" is corrected to "nitrogen gas." (3) Delete the statement ``In this case as well, it is not necessary.'' from line 9 to line 1 of page 5 of the specification. (4) The word “air” on page 6, line 5 of the specification has been replaced with “
"Nitrogen gas," he corrected.

Claims (1)

[Claims] (1) In the manufacturing method of rare earth magnets, which includes the step of press-molding magnet material powder containing rare earth elements while applying a magnetic field in a direction parallel to the pressing direction, pressure is also applied when filling the powder into a mold. A method for manufacturing rare earth magnets that is characterized by applying a magnetic field in a direction parallel to the direction of the magnet.