JPS61276310A - Magnetizing method for permanent magnet - Google Patents

Abstract

PURPOSE:To enable continuous use of a magnetomotive coil by restraining the generation of heat of this coil, by shortening the generation interval of the magnetic field to specified interval to act on a magnet body as a magnetomotive magnetic field. CONSTITUTION:The electric charge which is charged on a power source device is discharged to a magnetomotive coil connected to the high-tension line by a thyristor switch, and the magnetic field for magnetizing is generated. When the magnetizing power gets to the peak the thyristor switch is switched therefor the current can be passed to the discharge circuit in the power source device from the magnetomotive coil, and the magnetomotive magnetic field is focused abruptly at the point of rising-up and falling-down of the current. Consequently, the generating interval is to be shortened in this case to 60musec-5msec, by changing the constants of the power circuit for magnetizing, thereby, the sharp waveform for the rising of the magnetizing power is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of magnetizing a resin bonded rare earth permanent magnet.

[Summary of the invention]

The present invention provides a method for magnetizing a resin-bonded rare earth permanent magnet, including changing a part of the circuit of a magnetizing current supply device (hereinafter referred to as magnetizing power supply device) to generate a magnetic field that acts as a magnetizing magnetic field on the magnet body; By changing various constants, a magnetizing coil connected to the magnetizing power supply device is generated for 60 μsec to 5 seconds, and the resin-bonded rare earth permanent magnet set in contact with the magnetizing coil is magnetized. [Prior art] Conventional magnetization of resin-bonded rare earth permanent magnets is described in Japanese Patent Application Laid-Open No. 1999-59111.
-103552, the magnetizing current gradually rises over time, reaches its peak, and takes several times to several tens of times the time from the rise to the peak. Since a magnetizing current that terminates in a sweeping manner was used, the magnetizing magnetic field generated in the magnetizing coil connected to the magnetizing power supply also conformed to the magnetizing current waveform.

[Problem that the invention seeks to solve]

However, in the above-mentioned prior art, the magnetizing magnetic field gradually rises in the magnetizing coil over time, and the magnetic field is generated for a long time, about 35 to 40 degrees, gradually tapering off over time. For this reason, the magnetizing current that is passed through the magnetizing coil must be passed for a long time, and the generated magnetic field can be improved even though the magnetizing coil is made of thin wires with a cross-sectional area of 2 to 208Q. Therefore, a large current of 5,000 to 12,000 μm was flowing at the peak current value. For this reason, the magnetized coil generates heat with the number of times it is magnetized, and the temperature rises so much that there is a risk of destruction of the coil, so it has not been possible to use it continuously despite cooling by water cooling, oil cooling, air cooling, etc. Therefore, it takes a long time to cool down. Alternatively, a plurality of the same magnetizing coils were made and used by switching them depending on the rise in temperature. In other words, there were problems such as poor work efficiency and an increase in the cost of the magnetizing coil.

The present invention is intended to solve these problems, and its purpose is to shorten the generation time of the magnetizing magnetic field, thereby suppressing the heat generation of the magnetizing coil and allowing continuous use of a single magnetizing coil. Our goal is to provide technology that improves work efficiency and reduces the cost of magnetizing coils.

[Means for Solving the Problem] The method of magnetizing a permanent magnet of the present invention stores electric charge in a capacitor of a capacitor-type magnetizing power supply device, discharges it to a magnetizing coil, and magnetizes the magnetizing coil with the current flowing at that time. This is to generate a magnetic field to magnetize a resin-bonded rare earth permanent magnet that is in contact with a magnetizing coil, and as shown in Figure 1, the waveform of the magnetizing magnetic field of the prior art is 20 to 40 vortices (8). 60μ
It is characterized by a waveform of the magnetizing magnetic field that converges in a short period of time in the form of a five-vortex type.

[Effect]

According to the above method of the present invention, a high voltage transformer is used in the capacitor of the capacitor-type magnetized power supply device to step up AC 200V to a predetermined high voltage, and the high voltage DC current rectified by the rectifier is stored as an electric charge, and charging is completed. do. Next, the previously charged capacitor is discharged by a thyristor switch to a magnetizing filter connected to this power supply device by a high-voltage wire having a large cross-sectional area and sufficient current capacity, and a magnetic field for magnetization is generated. At this time, as mentioned above, we changed part of the circuit of the power supply device, and when the magnetizing current first reached its peak (that is, when the magnetizing magnetic field reached its maximum), the Cyrisk switch was switched and the power was supplied from the magnetizing coil. A current flows through the discharge circuit inside the device so that the magnetizing magnetic field rapidly converges when it rises and then falls, and by changing various constants of the magnetizing power supply circuit, the rise of the magnetizing current, that is, the magnetizing magnetic field The waveform of the magnetizing magnetic field shown in FIG. 1 is made by making the rise steep, and the generation time of the magnetic field is shortened to 60 μm to 51% (8).

At this time, the resin-bonded rare earth permanent magnet that is in contact with the magnetizing coil or that is set inside the magnetizing coil is magnetized.

Therefore, the time for energizing the magnetizing film is extremely short, from 55 to 40 m5 ec to 60 m to 5 m5 ec, and no heat is generated.

〔Example〕

The method of magnetizing a permanent magnet according to the present invention was carried out using the method described above, and will be described in detail below. The magnetized power supply device has an output of 1500V (maximum) and a capacitor capacity of 600
μ? A part of the circuit was changed and various constants were changed to shorten the magnetic field generation time, and the magnetizing coil was φ2.611.
It is an air core type with 11 copper wires wound in 80 turns and is naturally air-cooled.It is equipped with a magnetized power supply and a 5Bsc4. It was connected with a high voltage cable.

Magnetized object used in this example (hereinafter referred to as magnetized sample)
is a cylindrical shape of φ10 x A7 and has a coercive force of about 1 (
This is a resin-bonded rare earth permanent magnet that has anisotropy in the axial direction of LOOO. First, regarding the magnetized sample, s m (coo, sys, Ouo, 018,
11'eO,! ! , Zr0.022) lLl was solution-treated at 1160°C for 112 hours, further aged at 810°C for 6 hours, and ground into powder with a particle size of 5 to 60μ and an average particle size of 25μ. What is called a rare earth intermetallic compound was used. 2% by weight of epoxy resin was added to this magnet powder and kneaded to obtain a mixture of magnet powder and resin. This mixture was pressed in a magnetic field of 15 KOe to form a φ11 x 79 m tube with anisotropy in the axial direction.
After solidifying by heating at 150° C. for 2 hours, the molded body was demagnetized to reduce the residual magnetism to 30 G or less at the surface, and further cut to obtain a magnetized sample of φIQXt711II. This sample was fixed at the center of the air-core magnetizing coil described above, and magnetization was performed while measuring the generated magnetic field with a Gauss meter. This Gauss meter is an analog type hold beak covered Gauss meter that has a measurement range from Do to 16KHK. The temperature of the magnetizing coil was measured using a digital thermometer by directly contacting the probe of the detection section with the surface of the magnetizing coil. First, the magnetic field generated by the magnetizing coil is set to 20
The output voltage of the magnetizing power supply device was adjusted to be 1Coo, and the temperature of the coil was measured with the discharge time interval for magnetization set to 40 seconds. According to the results, the surface temperature of the coil gradually rises after more than 10 magnetizing discharges, and the surface temperature of the coil gradually rises to room temperature (approximately 18°C).
) After 100 magnetizing discharges from the same level as
The difference was 22°C. For comparison, a conventional magnetizing power supply device was used, and the magnetizing coil 1. was measured under the same conditions. The same connection cable was used, and the magnetic field measurement method, temperature measurement method, and magnetization method were also carried out in the same manner. The magnetizing power supply device had a capacitor capacity II of 600 μm, and the generated magnetic field was adjusted by varying the output voltage, but compared to the power supply device of the present invention, it was necessary to use a slightly higher voltage to obtain the same magnetic field. The temperature on the surface of the magnetizing coil reached approximately 55°C after 40 magnetizing discharges, and the temperature inside the coil was considerably higher than the surface temperature, which was dangerous, and the process was stopped when the temperature rose to 75°C.

FIG. 2 shows a comparison of the temperature rise on the surface of the magnetized coil between the magnetization method of the present invention and the prior art method.

In addition, the generation time of the magnetizing magnetic field is 1.2 times in the method of the present invention,
In the conventional technology, the time is 255 seconds, which is about 1'9 times longer, which is quite long. In addition, in order to check the quality of magnetization depending on the magnetization time, the magnetized sample fixed in the magnetization coil was taken out after only one initial magnetization, and the end surface was touched with a Hall probe using the Gauss meter described above. When measured, the sample obtained by the magnetization method of the present invention showed a surface magnetic flux density of about 1760G, and the sample obtained by the conventional magnetization method showed a surface magnetic flux density of about 1770G, indicating that there was no problem in magnetization. It became clear.

〔Effect of the invention〕

As described above, according to the method of magnetizing a resin-bonded rare earth permanent magnet of the present invention, the generation time of the magnetizing magnetic field is shorter than that of the conventional method, and is set to 60 μsec to 5 µs, so that the magnetization generated in the magnetizing coil is Without dropping the magnetic field, continuous magnetizing discharge is possible while suppressing the heat generation of the magnetizing coil, and there is no risk of damage due to temperature rise of the magnetizing coil, and multiple magnetizing coils can be prepared to adjust the temperature. This has the effect that there is no need to switch between uses due to the rise. In addition, water cooling, oil cooling, etc. have the same effect as cooling methods for magnetizing coils.In particular, when thin electric wires, where temperature rise is a problem, are wound once or several times around a magnetic material, the magnetizing jig is also heated. This has the effect of suppressing the rise and enabling continuous magnetization discharge. In the present invention, a magnetization method for a resin-bonded rare earth permanent magnet has been described, but the same effect can be obtained for permanent magnets bonded with resin other than what is generally called rare earth.

[Brief explanation of the drawing]

- Figure 1 is a magnetization waveform diagram showing the relationship between the magnetic field generated during magnetization and time. A...Curve according to the magnetization method of the present invention. B: Curves according to the conventional magnetization method are shown. FIG. 2 is a temperature rise diagram showing the relationship between the number of magnetizing discharges and the surface temperature rise of the magnetizing coil. a... magnetization method of the present invention,
b...Magnetization method using conventional technology. that's all

Claims (1)

[Claims] In magnetizing a permanent magnet made of rare earth intermetallic compound permanent magnet powder and a resin binder, the generation time of a magnetic field that acts as a magnetizing magnetic field on the magnet body is 60 μsec to 5 msec.
A method for magnetizing a permanent magnet, characterized in that the magnetization is within the range of .