JPS59103308A - Manufacture of permanent magnet - Google Patents

Abstract

PURPOSE:To obtain a resin bond magnet having a distinguished performance by a process having the steps of charging a die with a mixture containing magnetic powder of 2-17 rare earth metal and a specified amount of organic resin, and shaping the mixture in the die under the influence of a magnetic field at a temperature of 40- 150 deg.C. CONSTITUTION:A mold composed of a lower die 3, punch 4 and a peripheral die 6 is situated within a gap between a pair of solenoids each having a solenoid coil 1 and a pole piece 2. The die 6 is made of a non-magnetic stellite, while the punches 3 and 4 are made of normalized SuJ2. A mixture powder 5 contains R2TM17 rare earth metal magnetic powder consisting of a rare earth metal R and a transition metal TM, and 0.5-5wt% of organic resin as a binder. The mixture powder is charged in the die cavity formed in the die 6. The die is heated to a temperature of 40-150 deg.C by a heating medium which is circulated through a jacket 8 in a case 7 as indicated by arrows. In operation, a hydraulic press cylinder 11 is actuated to lower the punch 4 thereby compacting the mixture powder 5, while the mixture powder 5 is being heated by the heating medium and magnetized by a magnetic field developed between the pole pieces 2, 2. By this method, it is possible to obtain a permanent magnet which is superior both in magnetic property and mechanical strength.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a resin-bonded rare earth intermetallic compound permanent magnet.

Furthermore, in order to provide anisotropy by mixing magnet powder and a polymeric organic substance (or resin) as a binder, the mixed powder charged into a molding bottle is heated while being oriented in a magnetic field, and then pressurized. This relates to a method of manufacturing a permanent magnet that is (compression) molded.

What are the conventional resin bonded rare earth intermetallic compound magnets? a) Compression molding in a magnetic field was performed only at room temperature. Therefore, it has the following drawbacks or problems.

(1) The binder material is a liquid epoxy resin with a viscosity of 20,000 F8 or less.

(2) The filling ratio of magnet powder as a practically usable magnet material was about 80% by volume at most. For this reason, there was a limit to how much magnetic performance could be improved.

(3) Furthermore, since the porosity is 3 to 7%, it is a factor that lowers magnetic properties, and furthermore, it tends to deteriorate mechanical properties, and long-term reliability (temperature).

(4) When removed from the mold after pressure molding in a magnetic field, the shape or dimensions change due to the springback phenomenon, making it impossible to improve accuracy.

The purpose of the present invention is to overcome all the drawbacks of the above-mentioned conventional methods.
Improving the magnetic performance of resin-bonded rare earth intermetallic compound magnets,
Another object of the present invention is to provide a permanent magnet with improved mechanical properties, long-term reliability, and mass productivity.

Hereinafter, the method of the present invention for achieving the above object will be explained in detail.

The object of the present invention is a method for producing a resin bonded R,T M17 rare earth intermetallic compound permanent magnet.

The composition of R, TM17 type compound is as follows. If expressed as a general formula, R(Oo 1-u-v-w l
ll'e v Ouu My)w (Here, R is 8m,
One or a combination of two or more rare earth elements, mainly Oe, Pr, Y, La, Mid, Si, Ti
, 2:r, Hf, Nb, V.

One or a combination of two or more of Or, Mo, ¥n)
Therefore, a 2-17 rare earth intermetallic compound alloy having the following composition range can be applied. [1,1≦V≦0,4゜0.06
≦U≦0.15. uoυ1≦W≦0.05. .

An alloy ingot is used which is melted and cast so as to have the above composition range, where 10≦2≦85.

The macrostructure of the alloy ingot must be primarily in a state of advanced columnar crystallization. Next, the alloy ingot is subjected to heat treatment in a non-oxidizing atmosphere. First, in order to homogenize the alloy, it was heated at 1100℃~1200℃ for 1 hour~100℃.
After time solution treatment and rapid cooling treatment to room temperature, 500
C. to 900.degree. C., precipitation hardening treatment, and magnetic hardening.

Subsequently, the alloy ingot is passed through a hammer crusher'
After a coarse pulverization step using a ball mill, a fine pulverization step using a ball mill, a jet mill, etc., magnetic powder with a particle size of 2 μm to 10 μm is obtained. This 2-17 precipitation hardening magnet powder is mixed with an organic resin as a binder.

Mix the magnet powder and resin well in a mortar or in a mixing mixer if large quantities are used. Here, the ratio of the magnet powder to the resin is preferably 0.5% to 5% by weight of the resin. If it is less than 0.5%, mechanical properties tend to deteriorate even when the method of the present invention is used. It becomes difficult to completely cover the magnet powder with the binder.

If the thickness exceeds 1ζ or 5, the resin will ooze out during compression molding, the molded product will not be able to be removed from the mold, and defects such as cracks will easily occur, so this is what has been described above.

Next, an example of the compression molding method in a warm magnetic field is performed by the method shown in FIG.

A mold consisting of 3, 4, and 6 pieces is set between the gap between the electromagnets consisting of 1 electromagnet coil and 2 pole pieces. The outer mold 6 is made of non-magnetic stellite,
4 is the upper punch, 3 is the lower punch, and they are made of a material tempered from 5uJZ.

5 is charged with a mixed powder consisting of R, TM17 magnet powder and a resin binder. Next, 7 is a case for heating the mold to 40 to 150°C, and the space 8 has a structure in which a heating medium flows as shown by the arrow.

The heating medium enters from 9 and exits from v10 to heat the outer mold of 6. While heating the mixed powder of 5 with this, a magnetic field is generated between the upper and lower pole pieces of 2.
Compression molding is performed by pressing down a hydraulic press cylinder. This pressing force is 1tOrV/crA~4t, on/c+
Do it with 1. When the heating temperature is 40° C. or lower, organic resins with binding turbidity, that is, thermosetting resins are mainly used in the method of the present invention, but this fluidity is affected.

It has a poor effect on improving wettability with magnetic particles, and
If the temperature exceeds ℃, the resin decomposes and the magnetic particles are oxidized, which impedes the desired high performance.

In this way, by heating during compression molding in a magnetic field, the thermosetting resin that is the binder (binding material) easily wets the surface of the magnet powder, and the smaller the amount, the greater the effect. It was found by experiment. In addition, by heating, the viscosity of the binder temporarily decreases, and the degree of decrease is less than half of that at room temperature, making it possible to obtain products with particularly high viscosity, specifically 10,000 P8 to 100,000 PSO thermosetting resins. The effect was great. It has also been found that due to this effect, when the mixed powder is compression molded, the air in the molded product can be removed very easily and the porosity can be lowered. That is,
High density could be easily achieved.

Hereinafter, the method of the present invention will be explained in detail according to Examples.

Example 1 An R2 T Mlγ rare earth intermetallic compound alloy having the following composition was melted and cast to obtain an alloy ingot.

The composition can be expressed as a general formula: Sm (Ooo-1I.

Cuo, o7Feo, 12 Zro, 02 ) s, s
(This is a D 2-17 type compound. The melting was carried out in a low frequency furnace using Ar gas and cast into a mold. The temperature of the casting metal at this time was 1580°C.

Get:? ′! The macrostructure of the ingot was 80 cm or more (columnar crystals). The alloy ingot produced by such a casting method was subjected to precipitation hardening heat treatment by the following method. In an Ar gas atmosphere furnace, After heating at 1160°C for 4 hours, it was rapidly cooled to about 200°C at a cooling rate of 30 to 10 b/min.

Thereafter, the ingot which had been cooled to room temperature was subjected to a two-stage aging treatment in an Ar gas furnace at 800° C. for 2 hours + 740° C. for 3 hours, and then cooled to room temperature for 60 to 50 minutes. The ingot was coarsely ground using a hammer mill, and then a centrifugal ball mill was used to produce two fine powders having a particle size distribution of 3 μm to 80 μm. A predetermined amount of epoxy resin with a viscosity of 80,000 PS (centivoids) was added to each of the fine powders (magnetic powder) and mixed in a mixer to form a raw material before magnetic field molding. Subsequently, permanent magnets were manufactured under the conditions shown in Table 1.

Table 1 Manufacturing Conditions Figure 2 shows the percentage properties of magnets obtained under manufacturing conditions 11 or higher.
It is shown in Figure 3.

Figure 2 shows sample plates 1-1 to 1-4 and 2 pieces obtained by the conventional method.
Relationship between magnetic properties (b) and density (a,
) is shown. The correlation with magnetic field forming heating temperature was shown. It was also found from the change in density that heating during molding allows the binder epoxy resin to easily wet the surface of the magnetic powder, and also improves the compression molding ability.

Further, in FIG. 5, the amount of bond removal and the magnetic property (BE)max were investigated when the warm magnetic field forming temperature was kept constant at 45°C. In the conventional method, experiments were conducted using the magnetic field compression molding apparatus shown in FIG. 1 at room temperature without heating the mold.

As a result, the method of the present invention was able to obtain a high (BH)max regardless of the strength of the binder. It was found that the effect is particularly large in areas where there is little binding material.

This is very advantageous in achieving high performance of resin-bonded permanent magnets. In particular, it has the advantage of making it easy to increase the filling rate of magnetic particles.

Example 2゜8 m (OO, sls cube, 07 Feo, 1
Zro, oty)? , 8 A 2-17 rare earth intermetallic compound alloy prepared by the general formula is melted and cast.
I made a V4 ingot.

Next, after heating at 1140°C for 20 hours in an Ar gas atmosphere,
Cooling was performed at a rate of 80°C/min up to 500°C. The alloy ingot that had been subjected to the generalization treatment was heated at 800° C. for 20 hours to undergo an aging treatment.

This alloy ingot was coarsely ground, and the particle size was 5
A fine powder of μ to 80 μ was produced. 2.0wt to the magnetic powder
Add % of one-component epoxy resin and mix #! Mixed in a machine.

This mixed powder was processed using the magnetic field forming apparatus shown in Fig. 1.
A gold prismatic magnet with a sample shape of 4 x 8 x 30% was made. The heating temperature during magnetic field molding and compression in the method of the present invention was 50°C, and in the conventional method, it was 20°C.

Note that Table 2 shows the characteristic average values and variations when 10 magnet molded products were molded under the above molding conditions.

The method of the present invention can improve not only magnetic properties but also mechanical properties.

An increase in density was also achieved. Another feature is that it has the effect of reducing variations in each characteristic, which leads to the advantage of being able to reduce costs in mass production. Note that similar effects can be obtained if the binder (binding material) is a thermosetting resin. -18, 2-1
In the case of 7-series rare earth intermetallic compounds, similar results can be obtained for other compositions.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a compression molding apparatus in a warm magnetic field according to the method of the present invention. 1... Magnetizing coil 2... Magnetic pole (pole piece) 6... Lower punch of mold 4... Upper β 5... Mixed powder 6...Mold outer mold 7...Mold heating case 8...Mold heating medium 9...I l inlet 10...River l l outlet 11... Press ram Figures 2 and 3 are diagrams showing the characteristics obtained in Example 1 of the method of the present invention. Figure 2 shows the magnetic properties (BH)rnax and heating temperature Figure 5 shows the location of the binder 2) Third part I

Claims (1)

[Claims] R2TM17 type rare earth intermetallic compound consisting of rare earth metal (hereinafter referred to as R) and transition metal (hereinafter referred to as TM) @
An alloy ingot is made by the dissolution casting method, the alloy is heat treated, and a mixture containing magnet powder made through a powder mill and 0.5% to 5% by weight of an organic resin as a binder is prepared.
A method for manufacturing a permanent magnet, which comprises charging the mixture into a mold, heating the mixture to 40° C. to 150° C. and warm-forming the mixture while applying a magnetic field.