KR0140468B1 - Permanent Magnet Manufacturing Method - Google Patents

Abstract

RE-TM-B permanent magnets are made using round tubes. Place the tube between the upper punch and the lower punch and add magnetic powder. After the magnetic powder was added, it was hot pressed with an upper punch at a temperature of 400 to 1000 ° C. The powder then becomes an isotropic permanent magnet molded body. Subsequently, if necessary, the permanent magnet molded product is hot worked at a temperature of 400 to 1000 ° C. to produce an anisotropic permanent magnet.

Description

Permanent Magnet Manufacturing Method

1A-1E illustrate hot pressing and die upsetting operations in accordance with a preferred embodiment of the present invention.

2a to 2c are views showing a process for producing anisotropic permanent magnets by die-up-set the isotropic permanent magnet molded body in the tube as another preferred embodiment of the present invention.

3A and 3B show a die upset operation, according to a third preferred embodiment of the present invention.

4a to 4d show a hot compression and die upset operation of powder filled in a tube as a fourth preferred embodiment of the present invention.

5a to 5d show a die upset operation of an isotropic permanent magnet molded article produced by a conventional method as a fifth preferred embodiment of the present invention.

* Explanation of symbols for the main parts of the drawings

10,50: magnetic powder 12,52,72: (metal) tube

14,54,74: Isotropic permanent magnet molded body 16,56,76: Anisotropic permanent magnet

22,32: upper punch 24, 34: lower punch

26,36;

The present invention relates to a permanent magnet manufacturing method, and in particular, to a high-density isotropic magnet by hot compressing the magnetic powder in the tube, and to a permanent magnet manufacturing method for imparting magnetic anisotropy to the isotropic magnet by hot processing.

Generally, the manufacture of RE-TM-B permanent magnets consisting of one or more rare earth elements (RE), one or more transition metals (TM) and boron (B) (boron) There are two ways. One of them is a method of molding a powder made of RE-TM-B-based permanent magnet incoat in powder in a magnetic field, sintering and heat treatment at a temperature of 1000 ° C or higher. This is called a sintering method. This method is a costly and complicated method because the powder material has to be treated at high temperatures, and the material is easily oxidized.

The second method involves putting magnetic powder of amorphous and / or fine crystal grains obtained by rapid solidification of a molten alloy into a mold; Hot compacting the magnetic powder to obtain a densified isotropic magnet compact; It is a method of manufacturing an anisotropic magnet by placing the molded body in a die-up-set mold or hot working at a temperature of about 700 ° C. in the absence of a mold. This is called a hot working method. This method is simpler than the sintering method, and the material used is less likely to be oxidized. However, since the hot compression mold and / or hot working die-upset mold must be repeatedly used at high pressure and temperature, the mold tends to be easily deformed or broken. Therefore, in order to minimize such deformation and breakage problems, a mold made of a material having high rigidity and hardness must be used. In addition, since magnets can have various sizes and shapes, they are suitable for various size / shape conditions. Fabricating molds from hard materials is a difficult and expensive task.

It is therefore a primary object of the present invention to provide an economical method for producing anisotropic permanent magnets using copper and stainless steel tubes without the use of expensive molds.

According to one aspect of the present invention, a method for producing a permanent magnet containing one or more rare earth elements, one or more transition metals and boron, using a pressurizing device having at least one pressing member: (a ) Placing the magnetic powder containing the one or more rare earth elements, one or more transition metals and boron in the tubular member at the same height as the tubular member; (b) making the magnetic powder into a high density magnet, and acting the pressing member in one stroke at a temperature of 400 to 1000 ° C. to provide magnetic anisotropy to the magnet by hot working; And hot compressing and hot working the members together.

These objects and features of the present invention will be described in detail with the accompanying drawings.

According to a preferred embodiment of the present invention shown in FIGS. 1A and 1B, the magnetic powder 10 is hot-pressed to obtain the high-density isotropic permanent magnet molded body 4 by putting the magnetic powder 10 into a tube. A method is provided that includes compressing.

When the anisotropic permanent magnet 16 is required, as shown in FIGS. 1C to 1E, the isotropic permanent magnet molded body 14 may be hot worked. The hot working operation is performed by die upset processing, so that the isotropic permanent magnet molded body 14 has magnetic anisotropy.

In the present invention, a material comprising one or more rare earth elements (RE), one or more transition metals (TM) and boron (B) can be used. As rare earth elements, Nd is generally used, but Pr may be partially or entirely replaced. Fe is preferred in the case of transition metals, but it may be partially or entirely replaced with Co.

The magnetic powder 10 is made by powdering a permanent magnet material prepared by rapid cooling the molten alloy of the RE-TM-B permanent magnet material. The hollow tube 12 has a structure capable of producing a permanent magnet 16 of a desired shape and size. The length of the tube 12 is preferably longer than the height of the magnetic powder 10 contained therein. The tube 12 is preferably made of a paramagnetic or nonmagnetic metal such as, for example, copper or stainless steel, and may be made of a ferromagnetic metal such as iron.

As shown in FIG. 1A, the hot compression device 20 has an upper punch 22, a lower punch 24, and a heater 26. The upper punch 22 may be a structure that fits snugly within the tube 12. However, it is desirable to allow the upper punch 22 to slide within the tube, with a slight separation therebetween from the inner surface of the tube 12. In a preferred embodiment the upper punch 22 is round in shape. However, it should be understood that the shape of the upper punch 22 can be changed to match the cross section of the tube 12. The upper punch 22 is attached to the pressing means (not shown). The lower punch 24 may also be structured to fit snugly within the tube 12. However, it may also be slightly apart from the inner surface of the tube 12 to allow the tube 12 to be easily mounted to the lower punch 24. Likewise, the shape of the lower punch 24 may be changed to match the cross section of the tube 12. The lower punch 24 is also attached to the pressing means. Heater 26 surrounds upper punch 22, lower punch 24 and tube 12.

1C shows the die upset device 30. This die upset apparatus 30 has an upper punch 32, a lower punch 34 and a heater 36. The flat punch surface 33 in the upper punch 32 is wide enough to completely cover the workpiece. The upper punch 32 is attached to the pressing means (not shown). In addition, the flat punch surface 35 in the lower punch 34 is also wide enough to completely cover the workpiece. The lower punch 34 is also attached to the pressing means. A heater 36 surrounds the die upset device 30.

Referring back to FIG. 1A, the first step of the preferred embodiment is to put the magnetic powder 10 into the tube 12. The upper punch 22 is raised to its best position, as shown in FIG. 1A, so that the tube 12 can be easily positioned. The tube 12 is mounted over the lower punch 24 and then the magnetic powder 10 is poured into the tube 12 from a hopper (not shown).

After the magnetic powder 10 is put in, hot pressing operation is started. As shown in FIG. 1B, the upper punch 22 is moved downwards to magnetically press a pressure of, for example, 0.1 to 0.5 ton / cm ² at a temperature of 400 to 1000 ° C., preferably 700 to 800 ° C. By applying to the powder 10, a high-density isotropic permanent magnet molded body 14 is produced. This pressure may vary depending on the strength of the tube material and the thickness of the tube 12. The temperature is provided by a heater 26 such as, for example, a resistance heater. Workability is poor at temperatures lower than 400 ° C; At temperatures higher than 1000 ° C, the particles may coarsen. After the compression molding is completed, the upper punch 22 is moved to its best position, and then a portion of the tube 12 is removed by appropriate means such as a saw, so that the isotropic permanent magnet formed body 14 from the tube 12. Take out).

If necessary, following the hot compression operation, a die upset operation as shown in FIGS. 1C to 1E is performed. The isotropic permanent magnet molded body 14 is placed on the lower punch 34 of the die upset device 30 by any suitable means, for example a robot arm. Subsequently, the upper punch 32 is moved downward, and a pressure of, for example, about 2 ton / cm ² is applied to the isotropic permanent magnet molded body 14 at a temperature of 400 to 1000 ° C., preferably 700 to 800 ° C. Add. This temperature is obtained by the heater 36. During the above pressing process, the isotropic permanent magnet molded body 14 is plastically deformed and its height is reduced. By plastic deformation, the isotropic permanent magnet molded body 14 has magnetic anisotropy, and becomes the anisotropic permanent magnet 16. The easy magnetization axis of the anisotropic permanent magnet 16 is substantially parallel to the axis in the pressing direction. The anisotropic permanent magnet 16 may be pulverized to produce an anisotropic permanent magnet powder.

2a to 2c show a second preferred embodiment of the present invention with regard to die upset operation. The die-upset device 30 of FIG. 2A is identical in structure to the device of FIG. 1C.

In detail, after obtaining the isotropic permanent magnet molded body 14 by hot compression, it cuts out by suitable means, such as a saw, so that the part of the tube 12 as much as the height of the isotropic permanent magnet molded body 14 remains. It may be. After removing the portion of the tube 12 over the molded body 14, as shown in FIG. 2A, the die upset operation is started. When the tube 12 and the isotropic permanent magnet molded body 14 are hot worked together, the anisotropic permanent magnet 16 surrounded by the tube 12 can be obtained. When the anisotropic permanent magnet 16 is in the tube 12, it is preferable to prevent damage to the permanent magnet in the subsequent work, for example, work such as magnetization.

3a and 3b show a third preferred embodiment. The structure of the die upset apparatus shown in FIG. 3A is the same in structure as the apparatus shown in FIG. 1A. In this preferred embodiment, the anisotropic permanent magnet 16 is obtained by continuous hot compression / hot processing. That is, after the process of FIG. 1A and FIG. 1B mentioned above, hot processing is continued without removing the unnecessary part of the tube 12. FIG. Thereafter, the unnecessary portion of the tube 12 is removed to obtain a permanent magnet 16 surrounded by the tube 12.

4A to 4D, cross-sectional views for explaining the manufacturing method according to the fourth preferred embodiment of the present invention are shown. Also in this example, the hot compression and the die upset operation are performed continuously, but the point that each process is performed by the die upset operation is different from the third embodiment. That is, the magnetic powder 50 is put to the same height as the hollow tube 52, the upper punch 32 is moved downward, and compressed together with the hollow tube 52, so that the magnetic powder 50 is a high density isotropic permanent magnet. After the molded body 54 is pressed, the anisotropic permanent magnet 56 surrounded by the hollow tube 52 is obtained by continuing to pressurize.

5a to 5d show a fifth preferred embodiment of the present invention. According to this preferred embodiment, there is provided a method comprising inserting an isotropic permanent magnet molded body 74 into a tube 72 and hot working the isotropic permanent magnet molded body 74 to impart magnetic anisotropy. .

As shown in FIG. 5A, an isotropic permanent magnet molded body 74 manufactured by a conventional method is inserted into the tube 72. As shown in FIG. The height of the tube 72 is generally the same as the isotropic permanent magnet molded body 74. After inserting the isotropic permanent magnet molded body 74, the isotropic permanent magnet molded body 74 in the tube 72 is placed on the lower punch 34 as shown in FIG. 5B. Then, the isotropic permanent magnet molded body 74 in the tube 72 is pressed by the upper punch 32 to plastic deformation thereof. In this way, the anisotropic permanent magnet 76 is manufactured.

As described above, the permanent magnet can be manufactured without using a hot compression mold and / or a die upset mold.

Although the present invention has been described in terms of preferred embodiments, it will be apparent to those skilled in the art that modifications or variations will be made without departing from the spirit and scope of the invention as set forth in the claims.

Claims (13)

A method for producing a permanent magnet containing one or more rare earth elements, one or more transition metals and boron, using a pressurizing device having at least one pressure member, comprising: (a) the one or more rare earth elements Placing the magnetic powder containing one or more transition metals and boron in the tubular member at the same height as the tubular member; (b) making the magnetic powder into a high density magnet, and acting the pressing member in one stroke at a temperature of 400 to 1000 ° C. to provide magnetic anisotropy to the magnet by hot working; Permanent magnet manufacturing method comprising the step of hot compression and hot working together the member. The method of claim 1, wherein the tubular member is made of a metal. A method for producing a permanent magnet containing one or more rare earth elements, one or more transition metals and boron, using first and second pressurization devices each having at least one pressing member: Placing a magnetic powder containing one or more rare earth elements, one or more transition metals and boron into the tubular member; (b) hot compressing the magnetic powder in the tubular member by actuating the pressing member in the first pressing device at a temperature of 400 to 1000 ° C. such that the magnetic powder becomes a magnet molded body; (c) removing a portion of the tubular member that is greater than or equal to the height of the magnet molded body; (d) permanently comprising hot working the magnet molded body and the tubular member together by actuating the pressing member in the second pressurizing device at a temperature of 400 to 1000 ° C. to give magnetic anisotropy to the magnet molded body. Magnet manufacturing method. The method of claim 3, wherein the tubular member is made of metal. A method for producing a permanent magnet containing one or more rare earth elements, one or more transition metals and boron, using a pressurizing device having at least one pressure member, comprising: (a) the one or more rare earth elements Placing an isotropic magnetic molded body containing one or more transition metals and boron into the tubular member; (b) permanently manufacturing the isotropic magnet molded body by heating the isotropic magnet molded body and the tubular member together by actuating the pressing member at a temperature of 400 to 1000 ° C. such that the isotropic magnet molded body is plastically deformed to become an anisotropic magnet. Way. The method of claim 5, wherein the tubular member is made of metal. The method of claim 1, wherein the hot pressing step is characterized in that the permanent magnet manufacturing method is carried out at a temperature of 700 to 800 ℃. The method of claim 1, wherein the hot working step is a permanent magnet manufacturing method characterized in that carried out at a temperature of 700 to 800 ℃. The method of claim 1, wherein the hot pressing step and the hot working step is carried out at a temperature of 700 to 800 ℃ permanent magnet manufacturing method. 4. The method of claim 3, wherein the hot pressing step is performed at a temperature of 700 to 800 ° C. 4. The method of claim 3, wherein the hot working step is performed at 700 to 800 ° C. The method of claim 3, wherein the hot pressing step and the hot working step is carried out at a temperature of 700 to 800 ℃. 6. The method of claim 5, wherein the hot working step is carried out at a temperature of 700 to 800 ℃.