JPS60220910A - Anisotropic compression molding resin bonded magnet - Google Patents

Abstract

PURPOSE:To enhance heat-resisting propery as well as to block the slipping off of powder grains by a method wherein, when a compound permanent magnet is formed using yttrium, lanthanides rare-earth intermetallic compound powder, resin is impregnated into the cavity generated when a compression molding and a hardening by heat are performed in a magnetic field. CONSTITUTION:A solution treatment and an aging treatment are performed on the magnetic powder consisting of yttrium and lanthaides rare-earth metal element in a non-oxidizing atmosphere for the purpose of maintaining magnetic property, 0.5-8wt% of one-pack type or two-pack type epoxy resin binder is added to the above, and they are mixed and kneaded. Then, after the above- mentioned material has been compression-molded in a mold using a magnetic field of 8kOe or above, the above is heated up at 100-180 deg.C, and the resin binder is cured. Subsequently, the above-mentioned is placed in a vacuum vessel wherein one-pack type epoxy resin is filled, the degree of vacuum of 10<-1>-10<-6> Torr is obtained, and resin is impregnated into the cavities which were generated when the previous process is performed. These cavities may be filled by applying hydrostatic pressure instead of performing a vacuum treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to improvements in rare earth compression molded resin pound magnets. Specifically, the objective is to improve the thermal demagnetization characteristics of anisotropic compression molded resin bonded magnets.

[Prior art]

Practical methods for producing rare earth cobalt-based permanent magnets can be roughly divided into: (1) sintering method, (2) resin pound method, and are manufactured on an industrial scale. The sintering method (2) is the mainstream today, and its greatest advantage is high magnetic performance. However, since it is an intermetallic compound, the sintered compact is hard and brittle, so if care is not taken during processing and assembly, the defective rate will be high.

On the other hand, the resin pound method (2), which takes advantage of the characteristics of crack prevention, cost, and productivity, has rapidly penetrated the market. For example, they are widely used in fields such as small speakers, headphones, and micromotor step motors. However, the maximum operating temperature for these products, such as those for the consumer electronics industry and watches, is as low as 60°C to 80°C. For this reason, rare earth anisotropic resin pound magnets can be used satisfactorily for practical use, and the operating temperature limit is about 100° C. without any problems. However, with the expansion of applications, for example, copy machine mag roll,
There are many other items such as small motors for automobiles, dinutributors, print heads for printers, step motor meters, etc. All of these have been required to have high magnetic and mechanical reliability such as heat resistance and memory resistance.

For all of these products, the guaranteed temperature is -40°C to +80°C.
℃, high temperatures up to 120℃ are required. For this reason, the heat resistance of the parts is required to be as low as 100°C, and usually to be stable up to 150°C, and unless this requirement is met, it cannot be put to practical use. Conventional compression molded anisotropic rare earth magnets, such as JP-A-5
0-83797 etc. could not be supported at all. The irreversible demagnetization rate ΔΦ/φo×100 (ΔΦ=Φ equals Φ) changes as shown in FIG. 3, and the demagnetization rate becomes larger when the temperature exceeds +100°C. Excluding initial demagnetization, approximately -4% or less (T
(after oCX 1000 H) is the target value to be secured for practical use. In this way, the thermal practical limit of conventional compression molded resin bonded magnets is 100°C. Therefore, there was a problem that it could not be put to practical use in applications requiring heat resistance as described above.

〔the purpose〕

The present invention is newly proposed here as a result of extensive experiments and research in order to eliminate the drawbacks of such conventional methods. The first objective is to increase the heat resistance to 150° C., which satisfies practical needs magnetically and mechanically. The second iC is to prevent magnetic powder particles from falling off in practical situations and to greatly improve functional reliability.

〔overview〕

In order to achieve the above object, the present invention is characterized in that an anisotropic compression molded resin pound magnet is manufactured according to the following configuration. The specific configuration is described below.

(2) Ferromagnetic powder is an intermetallic compound consisting of yttrium, rare earth metal elements of the lantonide series, and transition metals listed in the periodic table.

(2) For example, specific alloy compositions include the following. smco5, EJWLOO4,6,BmOo
, , , 57n(C0a1L), ,ce(ao au
), , MM (an alloy composition having a so-called 1-5 crystal structure such as 1!0., with a powder particle size of 3 μm to 6 μm
Mainly uses the single magnetic domain particle diameter of .

E3m(Co bal c%1.o8Fgo, 22Zr
0,628) g, 3, Sm(Co bal Ou,,
, (,6”o, 32”rttolm)7.6T
Theory (Co b(Ll 04.12”go + )7.2
．． FmCOomL Gai r16BFeO, 12Zr6.
cH)7,4,57710,9 YO,I (00b
(LI C1to4 Fg(+,22)7,4,
S? 7ZO, 7? r. ,3(CObcLl.,...,F
eo, 22zro, C24)6. . , Smo, 7Ceo
, 3(CObcLl(:hiot'0.07zro, ora
)7. aoSm(OObalO210,12Feo,1
yT);3.01)? , 4'Bm Nd CCobal
Ou Fe Zr), etc. 0.80.20.
It is an alloy composition consisting of 2-17 crystals with a ratio of 0 to 0.3fi0.00+17.0, and the coercive force generation mechanism is caused by precipitation hardening, and the powder particle size is arbitrary from about 3 μm to 500 μm.

■ Heat treatment to ensure magnetic performance, such as solution treatment and aging treatment, is performed in a non-oxidizing atmosphere.

■　Process of mixing and kneading magnet powder and resin binder.

A thermosetting resin composition is used as the resin binder. - It is most preferred to use liquid or two-part epoxy resins. The mixing ratio with the magnet is 0.5wt% to 8w of resin.
T section is more preferable 1 wt%~6? I am in charge of nt.

■ Orient in a magnetic field and compression mold in a mold with a magnetic field strength of BKOe or higher. Here, a preferable magnetic field in consideration of basicity is at least 10 Koe, more preferably 12Xog or more and up to 25 Koe, which is the limit for a p, c (ilr flow) magnetic field. A magnetic field of about 50 Koe can also be applied in a pulsed manner. The compression pressure is applied up to 751'47mm2 considering the mold structure, material strength, etc., but usually it is 25hAyl'-60-gg considering mass production.
It is.

(2) The molded product, which is compression molded while being oriented in a magnetic field, is demagnetized by applying a magnetic field in the opposite direction to around IHc (intrinsic magnetic force) and extracted from the mold.

(2) The molded body is heated to 100 to 180°C to cure the resin binder.

(2) Next, the molded body is immersed in liquid resin and impregnated in a vacuum chamber. At this time, if the degree of vacuum is 101~-'TQrr, there will be no problem, and the impregnation will last for at least 05 hours (Figure 2-8)
.

Up to 3,000 yen at room temperature using a hydrostatic press
It is also possible to infiltrate the pores of the molded body with liquid resin under a pressure of Kg/cm 2 (Figure 2-B).

■ After cleaning the molded body, the impregnated layer is keyed again.
The present invention is characterized by producing an anisotropic compression molded resin pound magnet having a porosity of 2Vo1'ly or less.

The following will be described in detail according to examples.

[Example-1] A 2-17 rare earth intermetallic compound having the following alloy composition was melted in a low-frequency argon gas atmosphere to form an alloy ingot I.
I got Kg.

5tyt (OOb(LL On O, 08Fe O,
22ZγQ, 028)8+3' Since this alloy is a 2-17 series, it was magnetically hardened by the following heat treatment.

0 solution treatment: 11702°C x 25° after heating and holding for 4 hours
The mixture was rapidly cooled to 300°C using an oven.

○Aging treatment: 805"CX 26~ after 4 hours heating
The temperature reached 300°C in the 8″C layer.

Next, the alloy ingot that has undergone magnetic hardening heat treatment is coarsely crushed with a show crusher and then crushed with an attritor mill to a particle size of 3 μm.
It was made into magnet powder of ~80 μm. The particle size controlled powder is
-Add 2.1'wt% of liquid epoxy resin and kneader
It was kneaded with The kneaded mixed powder was molded into a magnetic compact using a compression molding mold in a magnetic field having the structure shown in FIG. The manufacturing conditions at this time are described below.

0 compression pressure...5t0'n7cm2 (50 land-
2) 0 magnetic field strength...Approximately 12KO11O Shape of compact ・Mountain...φ10XiOX axial ease o-? Near condition: Heating for i50”c×1 hour.

Note that this is the end of the comparison sample, and the permanent magnet molded product has been completed. Next, the method of the present invention includes a vacuum impregnation tank shown in FIG. 2-A and a hydrostatic pressure impregnation device Cc, x, shown in FIG. 2-B.
p, ) were respectively impregnated with -liquid epoxy resin. Table 1 shows examples of manufacturing conditions.

Table 1 shows the characteristics of the magnet molded body made under these conditions in Table 2.
Shown in the table. It was found that the porosity inside the molded body was greatly reduced, as evidenced by changes in density measurements and mechanical properties, and it was found to be very effective.

Table 2 Transverse rupture stress φ10 x 10 t ¥ The test was carried out using a round bar sample φ 2.5 x 10 t ¥ n cut from the sample with a distance between fulcrums of 6%. The comparative sample, which was compression molded and immediately processed, had a porosity of 5vO6Ll).

The reason for this is that air (gamma) escapes during compression molding (the gap between the punch 56 of the mold and the die 7), the molding speed, and the nulling back phenomenon during extraction from the mold. Understood.

The method of the present invention improves the performance of the molded article by impregnating the resin into the voids after the resin is exposed to the outside again.

[Example 2] Exactly the same sample as obtained in Example 1 (φ1゜×10
t%, L/D = 1), an irreversible demagnetization rate test was conducted under the following conditions.

(Comparative example sample) 0 heating source degree: 24-2°C950°C, 70"C, 80
℃, 90"C100℃, 12'0'C, 150"C
O heating time: ~1000 hours Pour into a constant temperature oven in two O heating devices (sample of the present invention)
90'C.

100℃, 120℃, 140℃, 150℃.

160℃, 180℃, 190℃ 0 heating time 2-1000 hours 0 heating device: Place in a constant temperature bath in the atmosphere.

Magnetize and apply 50Kog (pulse magnetization of oil capacitor set).

The measurement method is 80℃× after full magnetization for each temperature sample.
After heat drying for 1 hour, return to room temperature and measure all fujix using a fusix meter, and record the data obtained at this time. After 1000 hours had elapsed, the difference from the total flux Φl of the sample was measured again at room temperature.

Irreversible demagnetization rate=small i-Φ0×100 Φ0 A dental flux meter was used as the flux meter, and the measurement was performed while correcting with NMR and checking the accuracy.

Figure 3 shows the heating temperature and demagnetization rate of the comparative sample.The demagnetization rate curve becomes steep from around t90℃, and at 100℃, it becomes -3.
%, reaching a coefficient of 1-t-5 at 120°C. Therefore, the maximum operating temperature is around 1-t80°C to 100°C. −
Figure 4 shows the same demagnetization data as the comparative example for the strength wood invention method sample. (b) in the figure shows the method of the present invention in Figure 2-AK
Samples made by the vacuum impregnation apparatus shown, similar to (a,
) shows the data for the sample prepared by hydrostatic impregnation in FIG. 1-B. As can be seen from the diagram shown in Fig. 4, according to the method of the present invention, the irreversible demagnetization rate is from 11 inches up to 150°C.
It was found that there was no problem in practical use as it was on the order of -2.

As described above, according to the method of the present invention, heat resistance was increased to 150°C.

The biggest reason for the improved heat resistance is the effect of impregnating the pores inside the molded permanent magnet with resin. That is, the influence of the sudden air inside the molded body and the special oxygen (02) is σ. The method of the present invention has revealed that preventing oxidation at the magnet particle interface is extremely important for improving heat resistance. We were able to improve the performance of an orthogonal resin bonded magnet.

■Improved magnetic performance, especially magnetic stability.

In particular, the stability of magnetic flux against heat has been improved, and the practical range has been expanded to around 150°C. As a result, it has become possible to use it in automobiles, motors, meters, sensors, magrol dinutributors, etc., which had not been practical until now.

■The mechanical properties of the magnet molded body were improved.

By increasing the strength of the magnetic molded body, it is possible to extremely reduce the surface defects tM and k of the molded body during processing and assembly.
Production efficiency has been greatly improved. Conventionally, during secondary magnetization, magnet powder was attached, so a removal process was necessary.
According to the method of the present invention, there was no powder adhesion at all. It also has the effect of increasing the bonding strength between powder and resin. As described above, the method of the present invention has greatly increased the reliability of compression molded resin bonded magnets.

[Brief explanation of drawings]

Figure 1 shows a magnetic field forming device for compression molded anisotropic resin bonded magnets. 1...Hydraulic press ram 2...Pole piece (pure iron) 6...Yoke/coil frame 4...Magnetic field coil 5...Top Punch (ferromagnetic material) 6... Lower punch (ferromagnetic material) 7... Gui (non-magnetic material Stellite) 8...
・・Magnet + binder mixed powder 9・mountain・・support stand (SU
S304) Fig. 2 - Ad Fig. 2 -
B shows a hydrostatic impregnation device for the method of the invention. 10...Magnet molded body 11...Impregnation container (glass) 12...-Liquid epoxy resin 13...Vacuum chamber 14...Vacuum Seal parasenn 15...Rotary pump 16...Aragi pulp 17...Leak pulp 20...Magnet molded body 21...Protective container (Rubber) 22...-Liquid epoxy resin 23...Water for pressurization 24...Pressure container 25...Pressure pump 3rd The figure shows the magnetic flux demagnetization rate of an anisotropic resin bonded magnet made using a conventional method. FIG. 4 is a diagram showing the magnetic flux demagnetization rate of an anisotropic resin bonded magnet produced by the method of the present invention. (a)...A molded magnet impregnated with hydrostatic pressure. (b)... Vacuum-impregnated molded body magnet tool Applicant: Suwa Seikosha Co., Ltd. Representative Patent Attorney: Tsutomu Mogami Figure 1 Figure 8 ¥2, 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] An anisotropic composite permanent magnet consisting of yttrium and lantnide rare earth intermetallic compound magnet powder and a resin binder, which is compression molded in a magnetic field and heat cured, and the pores of the molded body are impregnated with resin. Compression molded resin pound magnet.