JPS60169119A - Manufacture of permanent magnet - Google Patents

Abstract

PURPOSE:To improve the orientation of magnetic anisotropy and to increase the magnetic flux density by a method in which fine powder of solid lubricant is eutectoid-plated on the surface of magnetic powder having uniaxial anisotropy, while the magnetic powder and the resin binder are melted and kneaded to be injected into and cured in a mold cavity applied with a magnetic field. CONSTITUTION:A metal composed of Sm2(Co, Cu, Fe, Zr)17 is melt and casted to obtain an alloy ingot. The ingot is subjected to solution treatment and to aging. The ingot is roughly ground and further control ground to obtain magnetic powder. The magnetic powder is added to a plating bath in which fine powder of graphite fluoride is dispersed in and mixed with N1 electroless plating liquid sufficiently. Stirring the mixture, eutectoid-plating on Ni and the graphite fluoride is performed to form a composite metal film on the surface of the magnetic powder. The magnetic powder is dispersed in and treated with a titanate coupling agent. The magnetic powder is dispersed in and kneaded with nylon 6 heated and melted by extruder kneading machine. The kneaded material is cooled to cure, and then ground to obtain pellets. These pellets are heated to be melted by a magnetic field injector. The melted material is injected into a mold cavity applied with a magnetic field and hardened.

Description

Detailed Description of the Invention [Technical Field] The present invention relates to magnetic powder having uniaxial anisotropy, such as ROO6 system,
This invention relates to a manufacturing method for obtaining an anisotropic permanent magnet by injection molding a resin filled with R200,7 series (R is rare earth) metal magnet powder in a magnetic field.

[Prior art]

In recent years, the method of manufacturing permanent magnets by injection molding has been rapidly increasing because compared to the sintering method, magnets with thin walls and complex shapes can be produced with higher precision, and the material cost and molding cost are lower. However, it has the following problems. There was ◎1,) Magnetic powder was V/o 50~6
Due to the high loading of 5%, in addition to the contact between the resin and the magnetic particles, there is also a lot of contact between the magnetic particles and contact between the magnetic particles and the mold, and the injection pressure is high, resulting in frictional resistance between the magnetic particles and between the magnetic particles and the mold. The magneto-crystalline anisotropic magnetic powder rotation in the magnetic field is hindered and the degree of orientation is poor. In other words, the magnetic energy of the original magnetic powder filling is not emitted.

2) Rare earth magnetic powder has a high hardness of 600 to 700 Hv, so the nozzle, cylinder, and screw of the mold and molding machine, in which the magnetic powder moves under high pressure and high speed, are subject to significant wear and must be replaced frequently. In particular, the molds were so worn that some were unusable after about 3,000 shots.

3) The material cost of rare earth magnets is 20 to 30 times higher than that of ferrite magnets, so the sprue, runner, and glue cycles that occur 50 to 70% of the time in injection molding are essential, but rare earth magnets are easily oxidized. When recycling is repeated, the magnetic performance deteriorates as shown in FIG.

4.) Among the methods for improving performance, high filling is said to have a big impact, but high filling is the opposite of improving formability, and high filling deteriorates fluidity and creates thin walls. [Purpose] The present invention eliminates these problems, and its purpose is to create a permanent magnet with excellent magnetic anisotropy orientation and high magnetic flux density. (Good moldability and recyclability. Less wear on molds and molding machines, less replacement of parts.

).

〔overview〕

In the present invention, the surface of magnetic powder having uniaxial anisotropy is coated with graphite butt, boron nitride, graphite, boron, molybdenum disulfide, PT.
Fine powder of solid lubricant such as FK is eutectoid plated using nickel, copper, etc. as a matrix metal, and then the magnetic powder and resin binder are melt-kneaded and injected into a mold cavity where a magnetic field is applied to solidify the anisotropic property. It is characterized by obtaining a permanent magnet.

〔Example〕

The present invention will be described in detail with reference to Examples below.

Component metals Sm2 (Co, Ou, Fe, Zr), 7 are melted and cast in an argon gas atmosphere in a high frequency furnace to produce an alloy ingot. Next, the ingot was heated to 1200℃ for 2
Solution treatment for 4 hours and aging treatment at 800° C. for 12 hours (argon gas atmosphere for both solution treatment and aging) are performed to homogenize the alloy and form precipitates in the alloy matrix to impart coercive force. Next, the ingot is coarsely pulverized and then pulverized in a Diflon with a ball mill to adjust the particle size distribution to 10μ to 100μ to produce magnetic powder. The reason why the process is always carried out in an argon gas atmosphere or in a Guiflon is to prevent Sm from being easily oxidized and deteriorating magnetic performance.

Next, the atomized graphite (a y )− was added to the N1 electroless plating solution.
Add the fine powder of 18% by V/O to the plating bath in which the N1 electroless plating solution and the fine powder of fluorinated graphite were sufficiently dispersed and mixed by high-speed blending. A composite metal film with a thickness of 1 to 2μ is formed on the surface of the magnetic powder by electrolytic plating. ◇The reason we chose graphite as the solid lubricant here is that it has a low specific gravity of about 2.5 and has good dispersibility during plating. This is because it has excellent heat resistance (stable even at 400°C under atmospheric pressure).

Next, the magnetic powder is placed in a titanate coupling agent diluted with toluene, and toluene is distilled in while stirring with a Henschel mixer to disperse the titanate coupling agent in the magnetic powder. Thereafter, 60% of this magnetic powder is added to nylon 6 heated and melted at 270°C in an extrusion mixer, dispersed and kneaded, and after cooling and solidifying, the powder is crushed into 1-2W square pieces to form pellets. Next, the pellets are heated and melted at 300° C. using a magnetic field injection molding machine, injected into a mold cavity to which a magnetic field of 18,000 G is applied, and then cooled and solidified to obtain an anisotropic permanent magnet.

Since the present invention is a manufacturing method having the above configuration, a composite metal film with excellent lubricity is formed on the surface of the magnetic powder, and (1) friction between the magnetic particles and between the magnetic particles and the mold is generated during orientation in a magnetic field. The resistance was reduced, the magnetic particles were easier to rotate, the degree of orientation was improved, and the magnetic flux density was high.

(2) Since the composite metal film serves as an oxidation prevention film for the rare earth magnetic powder that is easily oxidized, the decrease in magnetic performance due to recycling is reduced as shown in FIG. (3) As in (2), the formation of an antioxidant film has a great effect on improving fluidity, but the titanate coupling agent, which had a strong acidity of pH 2.4 to 41 and could not be used, can now be used. Stable moldability. Also, due to the improved fluidity, it was possible to lower the injection pressure, and as in (1), the frictional resistance was reduced and the degree of orientation was improved. Table 1 shows a comparison of the surface magnetic flux of the present invention and the conventional method. The magnet is 1μ thick.

Table 1 *1100% virgin *2 Add 50% recycled product 0 As shown in Table 1, the degree of orientation can be improved by approximately 10% by improving the lubrication of the composite metal film, and approximately 14% by improving the degree of orientation by using a titanate coupling agent. Improvement was measured. Furthermore, if the oxidation prevention aspect of recycling is included, the improvement was actually about 19%.

(4) Improved lubricity on the surface of magnetic particles reduces wear on molds, molding machine nozzles, cylinders, and screws, reducing parts replacement! What used to be done with 1,000 to 7,000 shots did not seem to be necessary even after 20,000 shots.□In addition to the face wood example, there is no problem with the following contents. 1.) Solid lubricant Add two or more types of fine powder.

2.) Add fine powder of carbide, nitride, or ferromagnetic material along with solid lubricant.

5) Use electrolytic plating method.

4) Layering different metal films. (However, the outermost periphery is a composite metal film containing a solid lubricant.) [Effects] As described above, according to the present invention, permanent magnets with excellent magnetic anisotropy orientation and high magnetic flux density can be easily produced (◎ Formability Good, ◎
Good recyclability・◎ Less wear on molds and molding machines,
Few parts need to be replaced. ).

[Brief explanation of drawings]

Figure 1 shows the changes in magnetic performance due to conventional recycling.
The figure shows changes in magnetic performance due to recycling according to the present invention. Applicant Suwa Seikosha Co., Ltd. Tsutomu Mogami 0 1) 3 y Recycling 1st loss Figure 1 O; Zeta stone? ~c5- 9-sun Iful Kai Figure 2

Claims (1)

[Claims] In the method of manufacturing permanent magnets using the injection molding method, magnetic powder, whose surface is eutectoid plated with fine solid lubricant powder to form a composite metal film, is melted and kneaded with a coupling agent, a resin binder, etc., and then a magnetic field is applied. A method for manufacturing a permanent magnet, characterized by obtaining an anisotropic permanent magnet by injection solidification into a mold cavity.