JPH0785458B2 - Rare earth magnet manufacturing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a resin-bonded rare earth magnet composed of rare earth metal compound magnet powder and an epoxy resin.

[Conventional technology]

Conventionally, the manufacturing method of mixing rare earth intermetallic compound magnet powder consisting of rare earth metal and transition metal with epoxy resin as a binder and press-molding in a magnetic field is a mold or die using a DC electromagnet and a hydraulic press. Is used as a magnetic circuit using a part of the above and the press body, the magnet powder is orientated in radial anisotropy, pressure molding is performed, and then the resin is taken out of the mold and the epoxy resin is heated and solidified. Also known is a manufacturing method in which a transversely anisotropic magnet having a simple magnetic field direction and a simple pressing direction is molded using an impact press using an air pressure source.

[Problems to be solved by the invention]

However, if the method of using the press molding die and the press body as a magnetic circuit, the rise time until the magnetic field for orientation reaches a peak is delayed, so it is not possible to follow up with a pulsed magnetic field, and a DC electromagnet is used. Since the pressurizing speed is synchronized with the rise of the magnetic field, forming is performed by a hydraulic press, which has a slower pressurizing speed than a mechanical press, resulting in low productivity in terms of forming time.

Also, the formed radial anisotropic magnet has a sharp tip waveform even if it is subjected to multi-pole magnetization due to its orientation, so the torque amount decreases when it is used by incorporating it into a motor etc. There was an occasion. Next, in an impact press using a pulsed magnetic field and an air pressure source, although the press molding itself has high productivity, the supplementary processes such as magnet powder supply and molded product removal cannot keep up with the speed.
As a result, the method has a low productivity, the advantages of the impact press are not produced, and the molded product has a problem that only a simple transverse anisotropic magnet can be molded. The present invention is to solve the above problems, and an object of the present invention is to provide a motor having a high peak value of the surface magnetic flux density waveform of the magnet when performing multi-pole magnetization, and having a large area. It is an object of the present invention to provide a highly productive manufacturing method capable of efficiently producing a polar anisotropic permanent magnet capable of obtaining a torque amount when used by a mechanical press and a pulse magnetic field orientation, which have a shorter forming time than hydraulic press forming.

[Means for solving problems]

The method for producing a rare earth magnet of the present invention is a method for producing a rare earth magnet in which the basic composition is a mixture of a rare earth metal compound magnet powder made of a rare earth metal and a transition metal and a binder made of an epoxy resin, and pressure-molded in a magnetic field. In addition to orienting polar anisotropy in a pulsed magnetic field of 0.5 seconds or less, press molding by mechanical press so that the peak of the pressure applied to the molded product comes 10 to 410 msec behind the peak of the pulsed magnetic field. In addition, when the subsequent magnetization is performed, a pulse magnetic field is applied to perform multi-pole magnetization.

〔Example〕

 Hereinafter, the present invention will be described in detail based on examples.

The rare earth magnet powder used is represented by the general formula Sm (Co
_0.627 Cu _0.08 Fe _0.22 Zr _0.028 ) _8.35 was used as the 2-17 series rare earth intermetallic compound alloy. This alloy was pulverized to a magnetic powder with a particle size of 2 to 80 microns using a ball mill. 2% by weight of a thermosetting two-component epoxy resin was added as a binder to 98% by weight of the powder thus produced, and mixed to obtain a resin-bonded rare earth magnet powder.

FIG. 1 shows the pressure molding apparatus used in this example.

In this pressure molding apparatus using a friction press, a Masatsu wheel (A) 6 and a Masa wheel (B) 7 that rotate in the same direction slide in the same axial direction, and the Masa wheel (C) 8 is rotated to rotate in this rotation direction. Thus, the upper punch 2 and the upper core 5 made of a non-magnetic material are moved up and down to apply pressure, and the upper ram is raised.
The magnet powder is filled in a space 9 surrounded by the magnetic field yoke 1, the lower punch 3 and the lower core 4 made of a non-magnetic material, and is pressure-molded by the upper punch.

FIG. 2 is a detailed view seen from the upper surface of the magnetic field yoke 1 used as a mold. The magnetic field yoke is made by cutting a groove of pure iron, which is a magnetic material, as shown in the figure.
It is used in the same manner as in the case where a ring-shaped permanent magnet is magnetized in multiple poles by applying a pulse current from a pulse magnetic field power source connected by a conductor 12. In order to use it as a press die and to avoid the influence of magnetism, for example, stellite made of a non-magnetic material is put as a die ring 10 in a portion in contact with the magnet powder, and the upper and lower punches 2 and 3 are made of a non-magnetic super material. A non-magnetic metal such as hard was used. The magnetic lines of force 13 when a pulse current is flown flow through the space 9 so as to come out from the convex portion of the magnetic field yoke 1 and flow into the adjacent convex portion, whereby the filled magnet powder is oriented. Incidentally, in FIG. 2, the coil 11 and the magnetic force line 13 are omitted from each half so as to make the drawing easy to see. Further, as described above, the magnet powder oriented in polar anisotropy is disturbed in its orientation when pressed when the pulse current passed through the coil 11 is stopped, so that as shown in FIG. The peak of the polar anisotropic magnetic field (H) generated and the peak of the pressing force (P) of the press are controlled by a separate control circuit so as to be synchronized with each other after a specific time (T). Typical conditions at this time are:
The maximum output of the pulse magnetic field power supply is 4000 V, 1200 μF, and the magnetic field curve output from the peak hold type Gauss meter by the hall probe placed in the space 9 shows that the peak of the magnetic field is about 25000 (0e), from the rise to the end to zero. Was about 41 msec, and pressurization by the press was set so that the peak of 3 ton / cm ² of pressurization was synchronized with the position T = 17.5 msec behind this peak. In this way, the magnet which is oriented in polar anisotropy and is pressure-molded reduces the residual magnetism of the magnet by passing a predetermined pulse current in the opposite direction to that of the orientation to the coil 9 before ascending the upper punch 2. Furthermore, the upper punch 2 is lifted up, and the lower punch 3 is lifted to remove the material from the space 9, heat and solidify it in a constant temperature bath at 150 ° C for 2 hours, and after the end face dimensioning process, outer diameter φ18, inner diameter φ16, height 4mm The ring-shaped resin-bonded rare earth magnet of Using a magnetizing yoke that has a structure similar to that of a magnetic field yoke in which a plastic spacer is inserted to apply a polar anisotropic magnetic field so that it closely adheres to the inner peripheral surface of this ring-shaped magnet, the magnetic poles are aligned and pulsed. It was magnetized by a power supply device. FIG. 4 shows the state after the magnetization. The magnet 14 oriented in polar anisotropy is combined with the spacer 15 to serve as a rotor magnet, and the magnetic field lines 13 generate N and S magnetic poles due to the flow of magnetic field lines similar to the orientation magnetism. When the surface magnetic flux density of this rotor magnet is measured with a Gauss meter and a Hall probe, the lines of magnetic force flow in the magnet.
Both the N and S poles are 1950 to 2100G, and the average is 2050G, which can be sufficiently used as a rotor magnet for a motor. As a comparative example, the magnet powder used in the present invention was used to mold a conventional DC electromagnet and a radial anisotropic magnet by a hydraulic press to obtain a ring-shaped resin-bonded rare earth magnet having similar dimensions.

The magnet size, the orientation magnetic field, and the pressing force are the same as those in the embodiment of the present invention, and a φ16 × φ14, height 4 mm pure iron ring is press-fitted so as to be in close contact with the inner peripheral surface, and a plastic spacer is inserted therein. Similarly, magnetization was performed by a pulse power supply device using a magnetizing yoke. The surface magnetic flux density is the result of the measurement
The N and S poles were 1920 to 2070G respectively, and the average was 2010G, which could be sufficiently used as a rotor magnet for a motor, but showed a value slightly lower than that of a polar anisotropic resin-bonded magnet. The measurement results are shown in FIG. Further, in the examples of the present invention, only one example of each condition at the time of molding is shown, but the result obtained by appropriately changing each condition is as follows.

Table 1 shows the time of the polar anisotropic pulse magnetic field (H) at the time of molding and the specific time (delay time T) at which the peak of the H and the peak of the pressing force (P) of the place are synchronized. The measurement result of the surface magnetic flux density when variously changed and molded is shown.

The peak of the magnetic field was adjusted on the side of the pulsed magnetic field power supply so that it would be about 25,000 (0e).
/ cm ² and the applied pressure (P) were not changed.

As shown in Table 1 above, by setting a specific time (T) such that the pressing force (P) ends while the polar anisotropic magnetic field (H) is generated, a high surface The magnetic flux density can be obtained.

However, if the (H) time is short, the orientation becomes difficult due to the (P), but if the (H) time is increased by 0.5 seconds or more, the heat generation of the coil of the magnetic field yoke increases and the resistance of the coil increases, which makes it difficult for the pulse current to flow. It becomes unpractical because the peak value of the magnetic field becomes small.

In the present embodiment, the parts around the mold other than the magnetic field yoke used a non-magnetic metal material, but if a similar molding is performed using a magnetic metal material for the lower core for the purpose of controlling the orientation direction of the molding magnet, If a magnetic ring is inserted in the portion of the spacer 15 shown in FIG. 4 that is in contact with the polar anisotropic magnet 14, it becomes a magnet having a surface magnetic flux density.

〔The invention's effect〕

As described above, according to the method of the present invention, in the molding of the resin-bonded rare earth magnet, the orientation by the mechanical press and the pulse magnetic field, the molding is performed, and the application time of the pulse magnetic field and the timing of the magnetic field and the pressing force are as described above. By setting, there is an effect that a polar anisotropic magnet having a high surface magnetic flux density can be manufactured by a highly efficient and highly productive method.

[Brief description of drawings]

FIG. 1 is a front view showing a molding apparatus used in this example. FIG. 2 is a top view showing the vicinity of the magnetic field yoke. FIG. 3 is a timing chart showing a magnetic field and a pressing force. FIG. 4 is a top view showing a magnetized molded magnet. FIG. 5 is a diagram showing surface magnetic flux densities of magnets of Examples and Comparative Examples. 1 …… magnetic field yoke 2 …… upper punch 3 …… lower punch 4 …… lower core 5 …… upper core 6 …… Masatsu car (A) 7 …… Masatsu car (B) 8 …… Masatsu car (C) 9 …… Space 10 …… Mold ring 11 …… Coil 12 …… Conducting wire 13 …… Magnetic field line 14 …… Polar anisotropic magnet 15 …… Spacer H …… Polar anisotropic magnetic field P …… Pressing force of the press T ... time

Continuation of the front page (56) Reference JP-A-58-200517 (JP, A) JP-A-55-115319 (JP, A) JP-A-59-216453 (JP, A) JP-A-60-206111 (JP , A) JP-A-53-85715 (JP, A) JP-A-60-88418 (JP, A) JP-A-61-243103 (JP, A)

Claims (2)

[Claims] 1. A method for producing a rare earth magnet, which comprises mixing a rare earth metal compound magnet powder having a basic composition of a rare earth metal and a transition metal with a binder made of an epoxy resin, and press-molding the mixture in a magnetic field. It is oriented in polar anisotropy in a magnetic field and is mechanically pressed from the peak of the pulsed magnetic field to 10
A method for producing a rare earth magnet, which comprises performing pressure molding so that a peak of a pressing force to a molded product comes with a delay of ~ 410 msec. 2. The method for producing a rare earth magnet according to claim 1, further comprising applying a pulsed magnetic field to magnetize the multipoles.