JP2014045044A - Rare earth-iron bonded magnet, and method for manufacturing rotor and electromagnetic device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a rare earth-iron bonded magnet simple and reduced in cost while having high magnetized properties, and adaptable even to a rare earth-iron bonded magnet having large heat capacity; and methods for manufacturing a rotor and an electromagnetic device using the rare earth-iron bonded magnet.SOLUTION: A heating set temperature of a device used in a magnetization process can be reduced by using a rare earth-iron bonded magnet before magnetized, the rare earth-iron bonded magnet including two or more kinds among Nd, Pr and Ce, as rare earth elements, and having a Curie temperature of 250°C or above and less than 290°C, so that a device used in magnetization process has a lower heating set temperature and magnetization condition has a relatively lower heating temperature, and the load of the device can be reduced. Accordingly, a rare earth-iron bonded magnet exhibiting high magnetized properties can be obtained even from a bonded magnet large in volume and high in heat capacity.

Description

  The present invention relates to a rare earth iron-based bonded magnet, a rotor using the same, and a method for manufacturing an electromagnetic device.

  Corresponding to recent downsizing of electronic devices and electromagnetic devices, stepping motors and the like used for the downsizing and diameter reduction are progressing. Along with this, since the diameter of the ring-shaped permanent magnet used as the rotor is also reduced, the magnetization pitch (distance between the magnetic poles) is narrowed, and multipolar magnetization is difficult.

As a multipolar magnetization method, pulse magnetization is generally used. In pulse magnetization, when a ring-shaped permanent magnet is magnetized, a large pulse current is passed through the magnet wire. However, if the magnetization pitch is reduced as the diameter of the ring-shaped permanent magnet is reduced, the current magnetizing jig uses a magnet wire. Therefore, there has been a problem that a pulse current that can sufficiently magnetize the magnet cannot flow. As a technique for improving this, there is known a method of magnetizing an object to be magnetized by reducing the saturation magnetization magnetic field to a temperature lower than the Curie temperature of the object to be magnetized (for example, Patent Document 1 and Patent Document). 2).
The present invention also relates to a method for magnetizing a permanent magnet, and a method for magnetizing a permanent magnet that continuously applies a magnetizing magnetic field while lowering the object to be magnetized from a temperature equal to or higher than its Curie temperature to a temperature lower than the Curie temperature. Is known (see, for example, Patent Document 3).

Japanese Patent No. 2940048 JP-A-6-140248 JP 2006-203173 A

However, the magnetization methods of Patent Document 1 and Patent Document 2 cannot obtain sufficient magnetization characteristics because of a limitation in current density. In addition, since a large current is instantaneously supplied to the magnet wire of the magnetizing coil as in the case of the conventional pulse magnetization, the possibility of dielectric breakdown is inevitable. Furthermore, the components of the magnetizing jig, particularly the mold resin, are likely to deteriorate due to exposure to high temperatures, and the life of the magnetizing jig tends to be extremely short.
In the magnetizing method of Patent Document 3, high magnetization characteristics can be obtained in an Nd—Fe—B based bonded magnet. However, since it involves high temperature heating, it is suitable for a small bonded magnet with a small heat capacity, but for a large bonded magnet. Is difficult to apply. In addition, as another issue, the demand for rare earth-based bonded magnets that exhibit high performance at a lower cost has increased due to the rising price of rare earths.

  The present invention has been made in consideration of such circumstances, and the object thereof is a rare earth iron-based bond magnet that can be applied to a bond magnet having a large heat capacity while being simple and reduced in cost while having high magnetization characteristics. Another object of the present invention is to provide a rotor and an electromagnetic device manufacturing method using the same.

  In order to achieve the above-described object, the rare earth iron-based bonded magnet according to the present invention is magnetized by heating to a temperature equal to or higher than the Curie temperature and lowering the temperature to a temperature lower than the Curie temperature while applying a magnetization magnetic field. A rare earth iron-based bonded magnet including a magnet-based magnet powder, wherein the rare earth iron-based magnet powder includes at least two or more rare earth elements, and the Curie temperature of the rare earth iron-based magnet powder is 250 ° C. or higher and 290 ° C. Rare earth iron-based bonded magnet characterized by being less than.

An apparatus to be used for heating by forming a bonded magnet containing rare earth iron-based magnet powder before magnetizing, including rare earth iron-based magnet powder containing two or more rare earth elements and having a Curie temperature of 250 ° C. or higher and lower than 290 ° C. Can be lowered, and the burden on the apparatus is reduced by lowering the heating temperature under the magnetizing conditions. Therefore, even a bonded magnet having a large volume and a large heat capacity can obtain a rare earth iron-based bonded magnet exhibiting high magnetization characteristics.
Further, by including at least two or more kinds of rare earth elements, the refining cost is reduced, and a simple and reduced rare earth iron-based bond magnet can be obtained.

The rare earth iron-based bonded magnet according to the present invention is characterized in that the rare earth iron-based magnet powder has an intrinsic coercive force of 716 kA / m (9 kOe) to 1590 kA / m (20 kOe).
By including a rare earth iron-based magnet powder having an intrinsic coercive force of 716 kA / m (9 kOe) or more, a rare earth iron-based bonded magnet having excellent thermal demagnetization characteristics and very low initial demagnetization characteristics can be obtained. .

The rare earth iron-based bonded magnet according to the present invention is characterized in that the rare earth element includes two or more of Nd, Pr, and Ce and does not include Co.
By including two or more rare earth elements of Nd, Pr, and Ce and not including Co, the magnet material price can be reduced and the Curie temperature can be lowered. Since the magnetizing condition is a relatively low heating temperature, the burden on the equipment is reduced, and magnets with a large heat capacity can be magnetized relatively easily. A magnet is obtained.

A rotor manufacturing method according to the present invention for realizing the above-described operation is a rotor manufacturing method using the rare earth iron-based bonded magnet, and magnetizing the rare earth iron-based bonded magnet is performed in the rotor manufacturing process. It is characterized in that it is performed in a process involving heating in which the object to be heated is exposed to a temperature of 250 ° C. to 290 ° C. for a short time.
By performing the magnetizing of the rare earth iron-based bonded magnet in a process that involves heating of the rotor manufacturing process, the magnetizing process that existed independently in the manufacturing process of the rare earth iron-based bonded magnet can be omitted, A method for manufacturing a rotor with reduced costs can be obtained.

The rotor manufacturing method according to the present invention is characterized in that a Curie temperature of the rare earth iron-based magnet powder is lower than a maximum temperature in the process involving heating.
Since the Curie temperature of the rare earth iron-based magnet powder is lower than the maximum temperature of the process involving heating, a simple and low-cost manufacturing method of a rotor provided with a rare earth iron-based bonded magnet having strong magnetic properties can be obtained.

Further, in the method for manufacturing a rotor according to the present invention, the step involving heating is an insert molding step, the rare earth iron-based bonded magnet is inserted into a molding die, and a magnetic field for magnetization is applied to the molding die. An application means is arranged, and heating of the rare earth iron-based bond magnet is performed by a heat-melted resin.
The insert mold process is a process that involves heating to set the injection temperature of the resin. If a magnetic field applying means for magnetizing is incorporated in the molding die used in the insert mold process, the insert mold process is performed with a rare earth iron-based bond magnet. Is heated by a heated and melted resin and then cooled, so that a process necessary for magnetization can be included, and a method for manufacturing a rotor that can further reduce costs can be obtained.

In order to realize the above-described operation, an electromagnetic device manufacturing method according to the present invention is an electromagnetic device manufacturing method using the rare earth iron-based bonded magnet. It is characterized in that it is carried out in a process involving heating in which the object to be heated in the production process is exposed to a temperature of 250 ° C. to 290 ° C. for a short time.
By performing the magnetizing of the rare earth iron-based bonded magnet in a process that involves heating of the electromagnetic device manufacturing process, the magnetizing process that existed independently during the manufacturing process of the rare earth iron-based bonded magnet can be omitted, A method for manufacturing an electromagnetic device with reduced costs is obtained.

The electromagnetic device manufacturing method according to the present invention is characterized in that a Curie temperature of the rare earth iron-based magnet powder is lower than a maximum temperature in the process involving heating.
Since the Curie temperature of the rare earth iron-based magnet powder is lower than the maximum temperature of the process involving heating, the heating temperature can be lowered and the electromagnetic device having a rare earth iron-based bonded magnet with strong magnetic properties is simple. And a low-cost manufacturing method can be obtained.

Further, in the method for manufacturing an electromagnetic device according to the present invention, the step involving heating is a reflow step, a magnetic field applying means for magnetizing is disposed in the vicinity of the rare earth iron-based bonded magnet, and the rare earth iron-based bonded magnet Is heated in a reflow furnace.
The reflow process is a process that involves heating to melt the solder in a reflow furnace. In the reflow process, a process necessary for magnetizing the rare earth iron-based bond magnet can be performed, and a method for manufacturing an electromagnetic device with reduced cost is provided. can get.

  According to the present invention, there is provided a rare earth iron-based bonded magnet that can be applied to a bonded magnet having a large heat capacity while having high magnetization characteristics, and which is simple and low in cost, and a rotor manufacturing method and an electromagnetic device manufacturing method using the same. Can be obtained.

(A) is a top view of the magnetization jig | tool and rare earth iron-type bonded magnet in 1st Embodiment, (b) is an AA longitudinal cross-sectional view in (a). The top view which shows the condition of the multipolar magnetization currently given to the rare earth iron system bond magnet. The figure which shows an example of the measurement result of the surface magnetic flux density of 10 pole magnetization. The figure which showed the dispersion | variation in the magnetization characteristic with respect to heating temperature and a magnetization characteristic in an Example and a comparative example. The figure which showed the magnetization characteristic with respect to the magnetization voltage at the time of performing pulse magnetization using the rare earth iron system magnet powder of an Example and a comparative example. The figure which showed the magnetization characteristic with respect to temperature control temperature in an Example and a comparative example. The top view of the structure of the magnetization part in 2nd Embodiment, and a rare earth iron-type bond magnet. The figure which showed the magnetization characteristic with respect to the sleeve thickness in an insert mold process. Schematic which shows the reflow process in 3rd Embodiment.

Hereinafter, the rare earth iron-based bonded magnet and the manufacturing method thereof according to the present invention will be described in detail by taking an embodiment as an example.
(First embodiment)
FIG. 1 shows a magnetizing jig 10 used in the method of manufacturing a rare earth iron-based bonded magnet according to the present embodiment and a rare earth iron-based bonded magnet 14 as an object to be magnetized. (A) represents a plan view, and (b) represents a longitudinal sectional view. In this embodiment, the ring-shaped rare earth iron-based bond magnet 14 is magnetized by 10 poles to obtain a multi-pole magnetized rare earth iron-based bond magnet 140.

The magnetizing jig 10 includes a non-magnetic block (for example, a stainless steel block) 12 provided with a circular magnetized material receiving hole 16 into which a rare earth iron-based bonded magnet 14 can be inserted and extracted, and is attached to the magnetizing jig 10. Ten grooves 18 having a rectangular section extending radially from the outer surface of the magnetic substance accommodation hole 16 are provided at equal angular intervals. In the grooves 18, magnetizing permanent magnets 20 are embedded as rod-shaped magnetizing magnetic field applying means having a square cross section having a Curie temperature higher than that of the rare earth iron-based bond magnet 14.
For example, an SmCo sintered magnet having a Curie temperature of about 850 ° C. can be used as the permanent magnet 20 for magnetization.

Hereinafter, a method for manufacturing the rare earth iron-based bonded magnet 140 multipolarized from the rare earth iron-based bonded magnet 14 will be described.
The manufacturing method of the rare earth iron-based bonded magnet 140 includes a heating step in which the permanent magnet 20 for magnetization is disposed in the vicinity of the rare earth iron-based bonded magnet 14 and the rare earth iron-based bonded magnet 14 is raised to a temperature equal to or higher than its Curie temperature. While the rare earth iron-based bond magnet 14 having reached a temperature equal to or higher than the Curie temperature is lowered to a temperature lower than the Curie temperature, a magnetizing magnetic field is continuously applied to the rare earth iron-based bond magnet 14 by the magnetizing permanent magnet 20. Magnetizing step.
As the rare earth iron-based bonded magnet 14 before magnetization, a bonded magnet made of rare earth iron-based magnet powder containing two or more kinds of rare earth elements and having a Curie temperature of 250 ° C. or higher and lower than 290 ° C. is used.

The rare earth iron-based bonded magnet 14 can be molded by, for example, compression molding.
By including two or more kinds of rare earth elements, refining costs can be reduced, and an inexpensive rare earth iron-based bonded magnet 14 can be provided.

In addition, it is preferable that two or more rare earth elements are included among Nd, Pr, and Ce, and that Co is not included. Both Pr and Ce have the effect of lowering the Curie temperature.
The addition of Co is indispensable for raising the Curie temperature and stabilizing it thermally in rare earth iron-based magnets, but by not containing Co, the magnet material price can be reduced and the Curie temperature can be lowered. That is, when the magnetizing condition is a relatively low heating temperature, the burden on the apparatus is reduced, and a rare earth iron-based bonded magnet having high magnetization characteristics can be obtained at a low cost. Furthermore, it is possible to relatively easily magnetize a magnet having a large heat capacity. In addition, since the thermal demagnetization characteristic is also lowered, there is an advantage that the magnetization characteristic can be easily adjusted.

In the heating step, the rare earth iron-based bonded magnet 14 is inserted into the adherend magnet accommodating hole 16 while being heated to the Curie temperature or higher.
In the magnetizing step, a magnetizing magnetic field is applied by the magnetizing permanent magnet 20. Then, the rare earth iron-based bonded magnet 14 is cooled to a temperature lower than the Curie temperature of the rare earth iron-based bonded magnet 14 while being installed in the magnetizing jig 10, and then taken out from the magnetized jig 10. For example, when the Curie temperature of the rare earth iron-based bond magnet 14 is Tc, it is particularly preferable that the rare earth iron-based bonded magnet 14 is heated to a temperature of (Tc + 30 ° C.) or higher and then cooled to a temperature of (Tc−50 ° C.) or lower in a magnetizing magnetic field. .
For heating, for example, any means such as resistance heating, high-frequency heating, laser heating, high-temperature gas flow heating, and high-temperature liquid heating may be used, but a high-frequency heating method capable of heating in a short time is particularly preferable. . Cooling may be performed by any method such as natural cooling, forced cooling such as water cooling, air cooling, gas blowing, and heating temperature adjustment. When work in an inert atmosphere is required, an inert gas flow is performed. The rare earth iron bond magnet 14 and the multipolar magnetized rare earth iron bond magnet 140 are easily and quickly inserted into the magnetized object accommodation hole 16 of the magnetizing jig 10 by a moving mechanism (not shown). It is preferable that the magnetic material receiving hole 16 can be easily and quickly removed.

  Through the steps described above, a magnetic pole corresponding to the magnetized magnetic pole appears on the outer peripheral surface of the ring-shaped permanent magnet that is the rare earth iron-based bonded magnet 14, and the rare earth iron-based bonded magnet 140 magnetized with multiple poles is obtained. . FIG. 2 is a plan view showing the state of multipolar magnetization applied to a ring-shaped permanent magnet which is a rare earth iron-based bonded magnet 140 that has been multipolarly magnetized. Reference numeral 22 represents the direction of the magnetizing magnetic field.

The evaluation of the magnetization characteristics can be performed quantitatively by measuring the surface magnetic flux density with a teslameter.
FIG. 3 is a diagram in which the surface magnetic flux density (open) Bo [mT] with respect to the central angle [degree] is measured on the outer peripheral surface of the multipolar magnetized rare earth iron-based bond magnet 140 with reference to an arbitrary point.
As shown in FIG. 3, the measurement is performed by changing the surface magnetic flux density (open) Bo [mT] with respect to the central angle [degree] with respect to the outer peripheral surface of the multi-pole magnetized rare earth iron-based bond magnet 140 with respect to an arbitrary point. Is obtained continuously. In the following examples, the average value of the Bo peak values (absolute values) of all poles was shown as the magnetization characteristic.

Hereinafter, embodiments will be described in more detail with reference to examples and comparative examples.
The rare earth iron-based bonded magnet 14 used in the following examples and comparative examples is a compression-bonded bonded magnet having an outer diameter of φ2.6 mm, an inner diameter of φ1.0 mm, and a thickness of 3 mm. ). And 10 pole magnetization (pole pitch 0.8mm) from the outer periphery is performed, and the magnetization characteristic is shown. The rare earth iron-based magnet powder was formed by pulverizing a quenched ribbon and mixing 2.5 wt% of an epoxy resin as a binder resin with the rare earth iron-based magnet powder.
Magnetization is performed using a magnetizing jig 10, changing the heating temperature, setting the heating time to 3 sec, cooling to a temperature adjustment temperature of 50 ° C., and taking out after 6 sec and the rare earth iron-based bond magnet 140 magnetized by multipolar magnetization. Got.

  Table 1 shows the composition, Curie temperature, maximum energy product, and intrinsic retention of the rare earth iron-based magnet powder used in the examples and comparative examples.

FIG. 4 is a diagram showing the magnetization characteristics with respect to the heating temperature and the variation of the magnetization characteristics in Examples and Comparative Examples. The left side of the vertical axis shows the magnetization characteristics, and the right side shows the dispersion of the magnetization characteristics. The magnetization characteristic was expressed as an average value of the pole peak values and a magnetization rate which is a ratio to the obtained maximum magnetization characteristic. The variation in the magnetization characteristics is a numerical value obtained by dividing the difference between the MAX value and the MIN value of the polar peak value by the average value of the polar peak values, and the smaller the value, the more stable the magnetization condition.
Black circles and black triangles indicate magnetization rates, and white circles and white triangles indicate variations in magnetization characteristics.

  In FIG. 4, it can be seen that in both the example and the comparative example, when the heating temperature exceeds a temperature near the Curie temperature, the high magnetization characteristics are stably exhibited. On the other hand, in the case of the example, high magnetization characteristics can be obtained even at a relatively low temperature of about 270 ° C. In other words, by limiting the Curie temperature of the rare earth iron-based magnet powder to 250 ° C. or more and less than 290 ° C., the set temperature of the magnetizing device can be further lowered, the burden on the device is reduced, and the rare earth iron having a large heat capacity It is also possible to deal with the magnetization of the system bond magnet 14. Therefore, it is possible to magnetize the relatively large rare earth iron-based bond magnet 14 in addition to the effect of reducing the manufacturing cost.

FIG. 5 and FIG. 6 show the results of evaluating the pulse magnetization and the magnetization characteristics in this embodiment.
FIG. 5 is a diagram showing the magnetization characteristics with respect to the magnetization voltage when pulse magnetization is performed using the rare earth iron-based bonded magnet 14 of the example and the comparative example used in the present embodiment.
In pulse magnetization, data was collected according to actual production conditions. The magnetization voltage of 600 V is the maximum condition (magnetization current density: 22 kA / mm 2) among the production conditions, and the general production condition is 450 V (magnetization current density: 16 kA / mm 2).
FIG. 6 is a diagram showing the magnetization characteristics with respect to the temperature control temperature in the examples and comparative examples in the present embodiment.
The heating temperature was set to 275 ° C. for the examples, the heating temperature was set to 310 ° C. for the comparative example, and the temperature control temperature was set widely to collect data.

In FIG. 5, it can be seen that the pulse magnetization exhibits a magnetization characteristic corresponding to the original magnetostatic characteristic. That is, the magnetization characteristics of the example are lower than those of the comparative example.
On the other hand, in the case of the present embodiment shown in FIG. 6, generally high magnetization characteristics are obtained as compared with pulse magnetization. In addition, it is understood that the examples show magnetization characteristics that exceed the comparative examples, and that high magnetization characteristics are obtained up to a temperature range exceeding the temperature control temperature of 200 ° C., despite the low Curie temperature.

(Second Embodiment)
In the rotor manufacturing method of the present embodiment, in the insert mold process, which is a process involving heating, the rare earth iron-based bonded magnet before magnetization is used as the object to be heated, and the magnetizing magnetic field applying means is disposed in the mold. Perform simultaneous magnetization. At this time, for example, a shaft or a spacer as an insert part can be arranged at the center of the rare earth iron-based bond magnet in order to manufacture a rotor for a motor.
If the insert molding process is a process involving heating with a temperature profile as in the first embodiment, the heating process and the magnetizing process can be performed. Further, a rare earth iron-based bonded magnet having a Curie temperature lower than the maximum temperature in the insert molding process is used.

FIG. 7 shows a plan view of the magnetized portion 1 and the rare earth iron-based bonded magnet 5 as the magnetized object in the second embodiment.
In FIG. 7, the magnetized portion 1 can be the same as that of the first embodiment. In this embodiment, the magnetized portion 1 is 24 pole magnetized and radiates from the outer surface of the magnetized object receiving hole 2. Extending 24 cross-sectional rectangular grooves 3 are provided at equiangular intervals. Magnetizing permanent magnets 4 are embedded as rod-shaped magnetizing magnetic field applying means having a square cross section whose Curie temperature is higher than that of the rare earth iron-based bonded magnet 5. The rare earth iron-based bonded magnet 5 is inserted into the magnetized object accommodation hole 2, and the heat-melted resin 7 is injected to the inner peripheral side of the rare earth iron-based bonded magnet 5. At this time, the rotor 9 for a motor is obtained by arranging the shaft 8 at the center of the rare earth iron-based bonded magnet 5.
The magnetized portion 1 is incorporated in an injection mold. The injection resin temperature is set to 270 ° C to 290 ° C.
Since the magnetized portion 1 may be a magnetizing mechanism that can apply a magnetic field of 200 kA / m (2.5 kOe) or more, it is not increased in size and can be achieved with a simple structure.

In addition, since it seems that there is a gap 6 between the magnetized portion 1 and the rare earth iron-based bonded magnet 5 in the insert molding process (for example, injection molding has a structure provided with a sleeve), the magnetic field analysis is sufficient. It was verified whether the magnetization characteristics were obtained.
FIG. 8 shows the result of calculation for a model with an actual insert molding process (outer peripheral 24 pole magnetization with respect to an outer diameter of 25 mm and an inner diameter of 22 mm).
In FIG. 8, even at an actual sleeve thickness of 0.5 mm, the decrease in the magnetization characteristics is only about 2%, and it was verified that the present invention is sufficiently effective.
The calculation result in FIG. 8 is the same as long as it is not a sleeve but a non-magnetic inclusion such as an air gap between the magnetic field generation mechanism and the adherend.

(Third embodiment)
In the electromagnetic device manufacturing method of the present embodiment, if the reflow process, which is a process involving heating, is a process involving heating with a temperature profile as in the first embodiment, the heating process and the magnetizing process may be performed. Is possible.
FIG. 9 shows a reflow process used in the method for manufacturing the electromagnetic device 300.
In FIG. 9, in the reflow process, first, cream solder 101 is printed on the substrate 100. For example, an element 110 as a component, and an electromagnetic element 120 including a rare-earth iron-based bonded magnet before magnetization used in the first embodiment. Be placed.
For example, a magnetized portion 130 similar to that of the first embodiment is arranged around the rare earth iron-based bonded magnet of the electromagnetic element 120 including the rare earth iron-based bonded magnet.
Next, the substrate 100 on which the element 110 and the electromagnetic element 120 including the rare earth iron-based bonded magnet are arranged is sent to and passed through the reflow furnace 200 provided with the heater 210. The temperature in the reflow furnace 200 is a temperature at which the cream solder 101 is melted, and is set to 270 ° C. to 290 ° C.
The cream solder 101 coming out of the reflow furnace 200 fixes the element 110 as the solder 102 and the electromagnetic element 120 including a rare earth iron-based bonded magnet.
Further, the rare earth iron bond magnet 120 becomes a magnetized rare earth iron bond magnet 121, and the electromagnetic device 300 is obtained.

The present invention is not limited to the embodiment described above.
The above description is an example of magnetizing a ring-shaped permanent magnet, which is a magnetized object, from the outside. However, the present invention can be magnetized from the inside or from both the inside and outside, similarly to the magnetization from the outside. It can also be applied to. With these magnetizing methods, magnetic poles corresponding to the magnetized magnetic poles appear on the inner peripheral surface or both inner and outer peripheral surfaces of the ring-shaped permanent magnet that is the magnetized object.
In the present invention, in addition to the configuration in which the magnetic field applying means for magnetizing is installed in only one stage in the axial direction, a configuration in which the magnetizing magnetic field applying means is arranged in two stages on the upper and lower sides is possible.
Further, skew magnetization can be realized, for example, by tilting and arranging permanent magnets for magnetization.

Furthermore, the shape and size of the rare earth iron-based bonded magnets mentioned as examples, the composition of the rare earth iron-based magnet powder, the Curie temperature of the rare earth iron-based bonded magnet, the Curie temperature of the permanent magnet for magnetization, etc. Selection is also possible.
In addition, the present invention can be variously modified and implemented without departing from the scope of the invention.

  DESCRIPTION OF SYMBOLS 1,130: Magnetization part, 10: Magnetization jig | tool, 2,16: Magnetized object accommodation hole, 3,18: Groove, 4,20: Permanent magnet for magnetization, 5: Rare earth iron-based bond magnet, 9: rotor, 12: non-magnetic block, 14: rare earth iron-based bonded magnet, 22: direction of magnetizing magnetic field, 121: magnetized rare earth iron-based bonded magnet, 200: reflow furnace, 300: electromagnetic device.

Claims (9)

A rare earth iron-based bond magnet including a rare earth iron-based magnet powder that is heated to a temperature equal to or higher than the Curie temperature and magnetized by lowering the temperature to a temperature lower than the Curie temperature while applying a magnetic field for magnetization,
The rare earth iron-based magnet powder includes at least two or more kinds of rare earth elements, and the Curie temperature of the rare earth iron-based magnet powder is 250 ° C or higher and lower than 290 ° C. 2. The rare earth iron-based bonded magnet according to claim 1, wherein the rare earth iron-based magnet powder has an intrinsic coercive force of 716 kA / m (9 kOe) to 1590 kA / m (20 kOe). 3. The rare earth iron-based bonded magnet according to claim 1, wherein the rare earth element includes two or more of Nd, Pr, and Ce and does not include Co. 4. A method for manufacturing a rotor using the rare earth iron-based bonded magnet according to any one of claims 1 to 3,
A method for manufacturing a rotor, comprising magnetizing a rare earth iron-based bonded magnet in a process involving heating in which a heated object in a rotor manufacturing process is exposed to a temperature of 250 ° C. to 290 ° C. for a short time. The method for manufacturing a rotor according to claim 4, wherein a Curie temperature of the rare earth iron-based magnet powder is lower than a maximum temperature in the process involving the heating. The process involving heating is an insert molding process,
Insert the rare earth iron-based bond magnet into a molding die,
Arranging magnetic field applying means for magnetization in the molding die,
The method for manufacturing a rotor according to claim 4 or 5, wherein heating of the rare earth iron-based bonded magnet is performed with a heat-melted resin. A method for manufacturing an electromagnetic device using the rare earth iron-based bonded magnet according to any one of claims 1 to 3,
A method of manufacturing an electromagnetic device, comprising magnetizing a rare earth iron-based bonded magnet in a process involving heating of an object to be heated in a manufacturing process of the electromagnetic device at a temperature of 250 ° C. to 290 ° C. for a short time. The method for manufacturing an electromagnetic device according to claim 7, wherein a Curie temperature of the rare earth iron-based magnet powder is lower than a maximum temperature in the process involving the heating. The process involving heating is a reflow process,
Arranging magnetic field application means for magnetization in the vicinity of the rare earth iron-based bond magnet,
The method for manufacturing an electromagnetic device according to claim 7 or 8, wherein the rare earth iron-based bonded magnet is heated in a reflow furnace.

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