JPH06295806A - Mn-al-c based thin plate magnet and production thereof - Google Patents

Abstract

PURPOSE:To ensure practical strength and magnetism by heating a quenching powder of Mn-Al-C based magnet powder and extrusion molding the powder into a rod which is then sliced and magnetized. CONSTITUTION:A quenching powder of Mn-Al-C based magnet alloy is encapsulated in an easily machinable capsule and heated. It is then extrusion molded into a rod having density of substantially 100%. The rod is then sliced in the direction normal to the extruding direction to produce a thin plate magnet having a thickness of 1.5mm or less which is then magnetized to produce a slice cut magnetized body. The slice cut magnetized body has a breakage resistance of 20kgf/mm<2>, and energy product lowering rate of 30% or less with respect to the basic material prior to cutting. This method ensures practical strength and magnetism.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-strength thin plate magnet used for ultra-thin motors, precision magnetic seals and the like, and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, OA equipment such as computers and AV equipment such as videos have been greatly reduced in size and improved in performance. Along with that, it is necessary to reduce the size and performance of parts such as motors and magnetic seals used in those devices. Especially, the thin plate magnets used for them have various strengths and characteristics. Research and development are being done.

Conventionally, as thin plate magnets used for small motors and magnetic seals, plastic magnets (plamag) produced by mixing powder magnets such as ferrite with a binder and injection molding or compression molding, and rare earth magnet powders. There have been rare earth magnets and ferrite magnets (sintered magnets) manufactured by sintering after being formed into a desired shape or cutting the sintered body.

However, the thin plate magnets obtained by these methods have the following problems in terms of strength and characteristics, so that there is a limit to the thickness that can be manufactured. Since there is no thin plate magnet having magnetic characteristics, it has been difficult to satisfy the recent demand for miniaturization.

Although a thin plate of a ferrite-based or rare-earth-based sintered magnet is formed by pressing powder at room temperature and then holding it at a high temperature for sintering, it is impossible to form the powder to 100% density by press forming at room temperature. Further, even if the sintering is performed, those holes remain in the sintered body as residual holes. In the case of a magnet with a large volume, these residual voids do not cause much problems, but in the case of a thin plate molded body, these residual voids easily become the starting points of fracture, so 1.5 mm or less and 20 kgf / mm ² or more. It is difficult to obtain one having practical strength. Therefore, in the current situation, both of them are required to be thinner than those limits by a method such as attaching a reinforcing plate.

As for magnetism, the characteristics of the magnet as the magnet deteriorates as the amount of the binder mixed increases, so that the requirement for high performance cannot be satisfied. Therefore, in order to meet the current demand for higher performance, it was necessary to develop a magnet that has sufficient strength and magnetic properties as a single magnet. Rare earth magnets have extremely high magnetic properties in a bulk state with a large volume, but since the crystal grains are large, the proportion of crystals that lose magnetism due to cutting increases as the thickness decreases, and the magnetic properties deteriorate due to subsequent oxidation, resulting in a low profile. It is difficult to obtain a high performance magnet.

As described above, there has been a limit to the range in which the conventional techniques and materials can cope with the demand for ever thinner thin plate magnets and higher performance.

[0008]

The problem to be solved by the present invention is to solve both of the above-mentioned drawbacks of the conventional thin plate magnet and the drawbacks of the manufacturing method thereof, and to have high strength and magnetic properties. Mn- with excellent characteristics and thickness of 1.5 mm or less
An Al-C based thin plate magnet and a method for manufacturing the same.

[0009]

Means for solving the above-mentioned problems are as follows: 1) A processable capsule-filled body of a quenched powder of Mn-Al-C magnet alloy is heated to a substantially 100% density. With a slice-cut magnetized body with a thickness of 1.5 mm or less in the direction perpendicular to the extrusion direction of the rod-shaped body, the bending strength is 2
An Mn-Al-C thin plate magnet having a reduction rate of the energy product with respect to the base material before cutting of 0 kgf / mm ² or more of 30% or less,
And 2) A quenching powder of Mn-Al-C based magnet alloy is put into an easily processable capsule and heated to obtain a rod-shaped compact having a density of substantially 100% by extrusion, and the compact is extruded in the extrusion direction. On the other hand, it is a method for manufacturing a Mn-Al-C based thin plate magnet in which a thin plate magnet material of 1.5 mm or less is obtained by slice cutting in the vertical direction and magnetized.

[0010]

The Mn-Al-C magnet has a weight ratio of Mn: 6.
5 to 74%, Al: 25 to 34%, C: 0.2 to 4.0
An anisotropic magnet having a basic composition of 10% by weight, which is based on a manufacturing method by powder extrusion described in the specification of Japanese Patent Application No. 62-237616 currently filed by the applicants in general. Is manufactured by. This is Mn-
The molten metal of the Al-C alloy is made into powder by gas atomizing, and the powder having an appropriate particle size distribution is put into an extruding capsule of a readily processable material and extruded by heating to obtain a round or polygonal rod shape having almost 100% density. A molded body is obtained and cut into short pieces to obtain a single magnet material.

The inventors of the present invention tried to find out how thinly a rod can be cut after extrusion, and it was confirmed that practical strength and magnetism can be secured with a thinness that has not been considered in the past, that is, a thinness that did not exist in the past. It was found that a thin plate magnet of Sasano can be obtained.

[0012]

[Table 1]

[0013] As described in the previous application, it is considered that the high performance conventional thin plate magnet is an Nd-based magnet. Although the Nd-based magnet has the highest BH _max among the magnets, the magnetic characteristics sharply decrease as the thickness decreases as shown in FIG. 1, whereas the thin plate magnet of the present invention does not decrease much. . That is, as shown in Table 1, the decrease rate of the Mn-Al-C based magnet is extremely small and good magnetic characteristics are maintained even when the thickness is 1.5 mm or less.

Regarding the transverse rupture strength, since the base of the Nd magnet is originally 10 kgf / mm ² or less, it is difficult to obtain a single-piece thin plate magnet having a practical strength of 1.5 mm or less. On the other hand, the Mn-Al-C magnet has an extremely high bending strength of 20 kgf / mm ² or more. Therefore, when actually cutting, as shown in Table 1, the magnet of the present invention has a resistance of 0.
Although it was possible to cut up to 15 mm, it is difficult to cut to 1 mm or less with an Nd magnet, and even if it can be cut, it is considered to be brittle and not practical.

The present invention uses M as a magnet material as described above.
An n-Al-C-based magnet material is used, which is put into a capsule and extruded into a rod-shaped body, sliced and cut into very thin pieces, and then magnetized, and a manufacturing method thereof. That is, the high mechanical strength that the Mn-Al-C based alloy also has as a basic characteristic and the fact that the crystal grains are finely homogenized by quenching have a small adverse effect of the thinness on the magnet work comprehensively. This is the realization of a thin plate magnet with high characteristics that has never existed before.

[0016]

EXAMPLES Mn: 68.8%, C: 0.44 in% by weight
%, Ni: 0.78%, the balance being Al, the molten metal of the alloy was atomized with Ar gas to obtain a spherical powder having an average particle size of 68 μm. This is poured and filled into a cylindrical capsule made of mild steel plate and having a diameter of 58 mm and a height of 80 mm, which is sealed and heated to 720 ° C., and the die is extruded twice to make a 16.3 mm round, and after cooling, the capsule material is removed by cutting to a diameter A round bar molded body of 16.0 mm was obtained. The density of the molded body was 5.08 g / cm ³ , the average grain size of the extruded material was 0.5 μm, and the transverse rupture strength of the sample taken in the direction perpendicular to the axial direction was 112 kgf / mm ² . This was cut into each thickness of 2.0 mm or less in the direction perpendicular to the axial direction by wire cutting. The results are shown in Table 1.

In the present embodiment, wire cutting was used as the cutting method, but it is industrially advantageous to use a precision thin blade rotary grindstone, and this also makes it possible to perform cutting in substantially the same manner as wire cutting.

The samples with the respective thicknesses shown in Table 1 were magnetized in the direction perpendicular to the plate surface to obtain thin plate magnets. The results of measuring these magnetic forces are shown in the same table. All of them show various properties that are practical as a thin plate magnet.

[0019]

By implementing the present invention, it is possible to provide a highly functional magnet having a thinness which has never been used as a magnet for a micro motor or as a magnetic sealing material, and it is possible to further reduce the size of OA equipment, video cameras, cameras and the like. And contributes to higher performance and higher performance.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the thickness and the decrease in magnetic force of a thin plate magnet of the present invention and an Nd magnet as a comparative material.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location B22F 3/24 G C22C 22/00 C22F 1/16 C H01F 41/02 G 8019-5E (72) Inventor Naoto Kuroda 3007 Nakajima, Shikoma-ku, Himeji-shi, Hyogo Sanyo Special Steel Co., Ltd. (72) Noriyuki Mano Nakajima, Shimo-ku, Himeji-shi, Hyogo 3007 Sanyo Special Steel Co., Ltd.

Claims (2)

[Claims] 1. A Mn-Al-C-based magnet alloy, which has a substantially 100% density in the direction perpendicular to the extrusion direction of a rod-shaped compact having a substantially 100% density obtained by heat-extruding a rapidly processable capsule-filled body of a powder having a thickness of 1.5 mm or less. Slice-cut magnetized body with 2 bending strength
Mn-Al having a reduction rate of 30% or less with respect to the base material before cutting at 0 kgf / mm ² or more
-C type thin plate magnet 2. A quenched powder of a Mn-Al-C based magnet alloy is put into an easily processable capsule and heated, and a rod-shaped molded body having a density of substantially 100% is obtained by extrusion processing, and the molded body is extruded in the extrusion direction. Slice cut vertically to 1.5mm
A method for producing a Mn-Al-C thin plate magnet, characterized in that the following thin plate magnet material is obtained and magnetized.