KR20000014044A - method FOR MANUFACTURING RARE-EARTH PERMANENT MAGNET - Google Patents

Abstract

PURPOSE: A method for manufacturing a rare-earth permanent magnet is provided to improve a magnetic characteristic of C type permanent magnet by heat plastic manufacturing into one stroke pressure process. CONSTITUTION: The method for manufacturing a rare-earth permanent magnet performing heat plastic manufacturing into one stroke process by putting a tube molding unit(10) filled with a rare-earth magnetic powder(12) made with rare-earth compound metal containing one more rare-earth elements or one more transition metals, boron to a metallic molding device(20) having a punch formed with a curved surface comprises the step of: forming a curvature of the tube molding unit surface contacted to a concave surface of the punch formed with the curved surface less than a curvature of the punch surface.

Description

Rare earth permanent magnet manufacturing method

The present invention relates to a rare earth permanent magnet manufacturing method, and more particularly, the degree of wrapping of the tube for the final product of the permanent magnet by improving the shape of the tube in the process of producing a C-type permanent magnet by hot firing using the tube The present invention relates to a method for producing a rare earth permanent magnet having uniform magnetic properties and excellent magnetic properties as a whole.

Generally one or more rare earth elements, one or more transition metals (abbreviated as TM) and one or more of boron (B), carbon (C), nitrogen (N) Permanent magnet compositions based on rare earth-based alloys containing compositions are already known, and such permanent magnet compositions are widely used in the electric / electronics industry, such as various motors, generators, computer parts, and acoustic devices.

Here, the rare earth element is neodymium (Nd), praseodymium (Pr), or both elements, and as the transition metal (TM), iron (Fe) or a mixture of iron and cobalt (Co) is used.

Their preferred composition is one comprising a Re ₂ ™ ₁₄ B phase.

Representative methods for producing permanent magnets based on such Re-TM-B alloys have been studied, such as the sintering process and the rapid solidification process.

According to the rapid solidification method, the Re-TM-B alloy is dissolved and then rapidly solidified by a melt spinning method to prepare an amorphous or microcrystalline ribbon having magnetic properties. The ribbon particles thus prepared are finely ground in a ball mill apparatus. Magnetized by die-upsetting process by inserting the pulverized ribbon particles into a hermetic or semi-sealed mold die and hot pressing process to form an isotropic permanent magnet and plastic deformation in hot again. A permanent magnet is produced in which the easy axis exhibits anisotropic properties in a direction substantially parallel to the pressing direction.

In another method of manufacturing, the specification filed by the applicant of the present invention is directed to a manufacturing process in which the hot compression molding process and the plastic deformation process are carried out in one stroke using a tube of a polygonal shape including a circle or a square. It is described in

Thus, the C-type rare earth-based permanent magnet manufacturing process using a conventional tube previously filed by the applicant is shown in Figures 1a to 1b.

According to this, the rare earth magnet powder 2 is produced, placed in the tube 3, and the tube molded body 1 is charged in the mold apparatus 4 heated to about 650-850 degreeC. In particular, the tip portions of the upper punch 5 and the lower punch 6 of the mold apparatus 4 so as to obtain a C-shaped permanent magnet corresponding to the curvature of the C-shape to be obtained, one punch is concave and the other punch is convex. Is formed. In addition, the bottom face 1a and the top face 1b of the tube molded body 1 are also molded to have the same curvature so as to be in contact with the curvature surfaces of the upper punch 5 and the lower punch 6 during charging.

In this way, when one side punch of the mold apparatus 4 is pressed in the state where the tube molded body 1 is charged, hot compression molding and plastic deformation process occur in a one stroke process, and are generally magnetic in a direction parallel to the axis in the pressing direction. It is made of permanent magnet with anisotropy.

However, in the rare earth-based permanent magnet manufacturing method using the conventional C-type tube 3 having a predetermined curvature on the bottom surface 1a and the top surface 1b, the density of the tube molded body 1 decreases gradually due to the compression process. On the other hand, the density of the tube 3 that surrounds the outer surface of the tube forming body 1 is caused to be covered with the lower surface 1a or the upper surface 1b. In particular, the tube 3 in contact with the curved surface having a concave shape is more easily covered, and this phenomenon not only reduces the magnetic properties of the permanent magnet 5 but also removes it or processes it into a permanent magnet having a uniform distribution. In order to perform the additional processing in order to increase the processing cost and the material cost had a problem.

Accordingly, the present invention is to solve such a problem, the curvature of the surface of the tube molded body in contact with the punch having a concave curvature surface in the process of producing a C-type permanent magnet by hot-firing in one stroke pressing process than the concave curvature The purpose of the present invention is to provide a method for manufacturing a rare earth permanent magnet having excellent magnetic properties as a whole by uniformly wrapping the tube.

In order to achieve the above object, the present invention relates to a mold apparatus having a punch formed with a tube-shaped body filled with a rare earth magnet powder made of a rare earth-based alloy containing one or more rare earth elements, one or more transition metals, and boron. In the rare earth permanent magnet manufacturing method which is hot-baked by the one-stroke process, the curvature of the surface of the tube molded body which is in contact with the concave surface among the curved punch formed is smaller than the curvature of the punch surface, the tube during compression processing The present invention provides a rare earth permanent magnet manufacturing method in which the magnetic powder causes plastic deformation uniformly.

The above objects and various advantages of the present invention will become more apparent from the preferred embodiments of the invention described below with reference to the accompanying drawings by those skilled in the art.

1a to 1b is a process diagram showing a conventional rare earth permanent magnet manufacturing process,

2 is a perspective view showing a tube molded article according to the present invention;

Figure 3a to 3b is a process diagram showing a rare earth permanent magnet manufacturing process according to the present invention.

<Explanation of Signs of Major Parts of Drawings>

10; Tube molded body 12; Magnetic powder

14; Tube 14a; (Tube) top

14b; (Tube) bottom 20; Mold device

21; Die die 22; Upper Punch

23; Bottom punch

Hereinafter, a rare earth permanent magnet manufacturing method according to the present invention will be described in detail with the accompanying drawings.

Figure 2 is a perspective view showing a tube according to a preferred embodiment of the present invention, Figure 3 shows a permanent magnet manufacturing process according to a preferred embodiment of the present invention.

According to the invention, one or more rare earth elements, one or more transition metals (abbreviated as TM) and one of boron (B), carbon (C), nitrogen (N) or A Re-TM-B alloy containing a Re ₂ TM ₁₄ B phase containing more elements is dissolved and then rapidly solidified by melt spinning to prepare amorphous or microcrystalline ribbons having magnetic properties. Such ribbon particles are finely ground with a ball mill device to form a magnetic powder 12.

On the other hand, the mold apparatus 20 is composed of a die die 21, the upper punch 22 and the lower punch 23, in particular to produce a C-type permanent magnet of the upper punch 22 and the lower punch 23 The distal end is formed into an arc-shaped curved surface.

In particular, the tube 14 for manufacturing the C-type permanent magnet is punched with a convex face when charged between the upper punch 22 and the lower punch 23, as shown in FIG. (22)) is formed to be concave with a curvature corresponding to the upper punch 22 so that the surface (upper surface 14a of the tube in the example drawing) in contact with the surface.

On the other hand, the surface in contact with the punch having a concave surface (the lower punch 23 in the exemplary drawing) (the bottom surface 14b of the tube in the exemplary drawing) is convex, but smaller than the curvature of the lower punch 22.

The magnet powder is put into such a tube 14 to form a tube molded body 10 and then charged into the mold apparatus 20. At this time, as mentioned above, the bottom surface 14b of the tube 14 has a curvature smaller than the curvature of the lower punch 23, so only a portion of the center portion of the bottom surface 14b contacts the lower punch 23, and the remaining portion thereof It will remain in an excited state (see FIG. 3A).

Subsequently, the mold apparatus 20 is pressurized by one stroke process, heating to about 650-850 degreeC, and the tube molding 10 is hot-pressed and plastically deformed.

The compression molding according to the one stroke process reduces the overall length of the tube molded body 10 and increases the molding density of the magnetic powder 12, thereby becoming a permanent magnet having high density isotropy. At this time, the tube 14 is bent in the inner side of the tube molded body 10 by a length that decreases as the length of the tube molded body 10 decreases. This process is performed in the state where the bottom surface 14b of the tube 14 is initially raised. As this progresses, the amount of the tube 14 that is bent inwardly is significantly reduced compared to the conventional structure.

Further compression processing further causes plastic deformation within the permanent magnet to form a permanent magnet having magnetic anisotropy in a direction parallel to the axis in the pressing direction (see FIG. 3B).

The shape of the C-type permanent magnet manufactured by such a manufacturing method has a final shape in which the tube 14 is formed to have a uniform thickness around the permanent magnet.

Therefore, in the related art, the tube 14 unevenly surrounds the permanent magnets, and thus, in order to obtain a uniform magnetic property, the post-treatment process, which requires cutting the thickness of the tube 14, must be performed. In the present invention, since the tube 14 forms a uniform thickness during the compression process, the post-processing process is unnecessary, thereby reducing the material of the tube 14 and simplifying the manufacturing process.

The foregoing is merely illustrative of a preferred embodiment of the present invention and those skilled in the art to which the present invention pertains may make modifications and changes to the present invention without changing the subject matter of the present invention.

Therefore, according to the present invention, by forming a narrower curvature of the tube in contact with the concave curved punch can obtain a tube of uniform thickness around the permanent magnet during compression processing, it is possible to suppress the post-treatment process and to reduce the tube material loss As a result, the magnetic properties of the permanent magnets can be improved.

Claims (1)

Tube forming bodies filled with rare earth magnet powders made of one or more rare earth elements, one or more rare metals and rare earth-based alloys containing boron are charged into a mold apparatus having a punch with a curved surface to be hot-baked by a one-stroke process. In the rare earth permanent magnet manufacturing method, The method of manufacturing a rare earth permanent magnet in which the curvature of the surface of the tube molded body which is in contact with the concave surface among the formed punches is smaller than the curvature of the punch surface to uniformly cause plastic deformation of the tube and magnetic powder during compression processing.