JP2009153230A - Method of manufacturing rotor core, rotor core manufactured by the manufacturing method, rotor core, embedded magnet type dynamo-electric machine having the rotor, vehicle, lift and working machine each using the dynamo-electric machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a rotor core which is easy to work and is inexpensive by increasing rotation speed while keeping low iron loss, and a rotor core which is manufactured by the manufacturing method, and a rotor, and an embedded magnet type dynamo-electric machine having the rotor. <P>SOLUTION: In the rotor for embedded magnet type dynamo-electric machines, which has magnet mounting holes 22 and 23 for mounting magnets inside the rotor core 21, the rotor core 21 is constituted of stacked steel plates, having hardenability, such as carbon steel or alloy steel, etc., and the bridge sections 24 and 25 around the magnet mounting holes 22 and 23 and the vicinity 26 and 27 of the bridge sections are quenched. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an embedded magnet type rotating electrical machine having a rotor of a type in which a magnet is mounted inside a rotor core, and in particular, a manufacturing method of the rotor core, a rotor core manufactured by the manufacturing method, a rotor thereof, and an embedded having the rotor. The present invention relates to a magnet-type rotating electrical machine, and further to a vehicle, an elevator, and a processing machine using the rotating electrical machine.

  BACKGROUND ART Conventionally, an embedded magnet type rotating electric machine having a rotor of a type in which a magnet is mounted inside a rotor core has always been improved for higher output and higher efficiency. One of the means for increasing the output is high-speed rotation, and one of the means for increasing the efficiency is reduction of iron loss in the rotor core. For this reason, an electromagnetic steel sheet having a low iron loss has been generally used as the material of the rotor core (see, for example, Patent Document 1).

FIG. 12 shows an example of a rotor core of an embedded magnet type rotating electrical machine in which a magnet is mounted inside a conventional rotor core, which is shown in FIG.
In FIG. 12, the rotor core 1 is provided with two magnet mounting holes 2 and 3 for mounting two magnets per pole. An outer bridge portion 15 is provided on the outer peripheral side around the two magnet mounting holes 2 and 3, and a center bridge portion 16 is provided at a position sandwiched between the two magnet mounting holes 2 and 3 on the inner peripheral side. .
In general, the rotor core 1 of an embedded magnet type rotating electrical machine is designed to minimize the width of the bridge portion around the magnet mounting holes 2 and 3 that become leakage flux paths in order to effectively guide the magnetic flux of the magnet to the stator core. Try. Therefore, the maximum rotational speed of the rotor is often limited by the mechanical strength limit of the bridge portion. As a means for achieving high-speed rotation, it is conceivable to increase the strength of the electrical steel sheet used for the rotor core, but it has been difficult to realize an electrical steel sheet having high strength and low iron loss.
In invention of patent document 1, the method of improving the intensity | strength of a bridge part is shown, using an electromagnetic steel plate with a low iron loss. Specifically, a part 11 of the outer bridge part and a part 12 of the center bridge part are work-hardened, and further a heat history is given by heat treatment, thereby improving the strength.

On the other hand, the present applicant intentionally saturates the rotor core by concentrating the magnetic flux of the magnet to reduce the change in magnetic flux density near the rotor core surface, thereby reducing the iron core of the rotor core without using a magnetic steel sheet with low iron loss. We found a way to keep the loss low.
According to this method, it is not necessary to use a magnetic steel sheet with good hysteresis characteristics for the rotor core that does not alternate magnetic flux, and it is considered that a higher strength steel sheet can be used with the same thickness, and a high strength quenching made of carbon steel. Using steel plates for the rotor core, both high-speed rotation and low iron loss were confirmed. In general, the strength limit of a general electromagnetic steel sheet is 500 MPa or less, whereas the quenched steel sheet has a strength limit of about 1600 MPa.
As described above, the rotor core of the conventional embedded magnet type rotating electric machine has achieved both high speed rotation and low iron loss.
Japanese Patent Laying-Open No. 2005-39963 (page 11, FIG. 2)

In a conventional embedded magnet type rotating electrical machine, it was easy to achieve low iron loss with a rotor core using a general electromagnetic steel sheet. For this reason, the width of the bridge portion around the magnet mounting hole that becomes the leakage flux path Therefore, it is difficult to realize high speed rotation due to weak mechanical strength.
Even in the conventional embedded magnet type rotating electric machine shown in Patent Document 1, the use of an electromagnetic steel sheet partially work-hardened enables high-speed rotation while maintaining a low iron loss. There is a limit to the strengthening, and sufficient high-speed rotation could not be realized.
On the other hand, the rotor core using the hardened steel sheet, which is the subject of the present invention, was able to achieve sufficient high-speed rotation while maintaining a low iron loss, but because of its high strength, the steel sheet has high hardness, so press forming However, the processing accuracy and mold life decreased. Moreover, since the heat quantity which quenches the whole steel plate is required, there also existed a problem which became an expensive steel plate.
The present invention has been made in view of such problems, and is intended to provide an inexpensive method for manufacturing a rotor core that achieves high-speed rotation while maintaining low iron loss, and is easy to process. Accordingly, another object of the present invention is to provide a rotor core manufactured by the manufacturing method, a rotor, an embedded magnet type rotating electric machine having the rotor, a vehicle using the rotating electric machine, an elevator, and a processing machine.

In order to solve the above problem, the present invention is configured as follows.
The rotor core according to claim 1 is a rotor having a magnet mounting hole for mounting a magnet inside a rotor core formed by stacking steel plates, wherein the steel plate is a hardened steel plate, and the vicinity of the magnet mounting hole is It is characterized by being quenched.
According to a second aspect of the present invention, in the rotor core according to the first aspect, the steel plate having hardenability is carbon steel or alloy steel.
According to a third aspect of the present invention, in the rotor core according to the first aspect, the vicinity of the magnet mounting hole is a bridge portion around the magnet mounting hole and the vicinity of the bridge portion.
According to a fourth aspect of the present invention, in the rotor core according to the first aspect, the magnet mounting hole is V-shaped with the center side of the rotor as a vertex for each pole.
According to a fifth aspect of the present invention, in the rotor core according to the first aspect, each of the steel plates has a non-conductive compound layer or a non-conductive compound layer formed by a surface treatment on the laminated surface.

The invention of a rotor core manufacturing method according to claim 6 is a method of manufacturing a rotor core having a magnet mounting hole for mounting a magnet inside a rotor core formed by laminating steel plates having hardenability. After processing into a set shape and laminating, it is performed using the magnet mounting hole, so that only the vicinity of the magnet mounting hole is quenched.
A seventh aspect of the present invention is the method of manufacturing a rotor core according to the sixth aspect, wherein the hardening process of the rotor core blows a flame through the magnet mounting hole and includes the bridge portion and the vicinity of the bridge portion. It is characterized by quenching the surroundings.
The invention according to claim 8 is the rotor core manufacturing method according to claim 6, wherein the hardening process of the rotor core includes the bridge portion and the vicinity of the bridge portion by passing a carburizing gas heated to the magnet mounting hole. It is characterized by gas carburizing and quenching around the magnet mounting hole.
According to a ninth aspect of the present invention, in the method for manufacturing a rotor core according to the sixth aspect, the hardening process of the rotor core is performed by inserting a laser torch into the magnet mounting hole and heating the bridge portion and the vicinity of the bridge portion by laser beam irradiation. It is characterized by quenching.
According to a tenth aspect of the present invention, there is provided a rotor according to any one of the first to fifth aspects, and a magnet mounted in the magnet mounting hole of the rotor core.
The invention of an embedded magnet type rotating electrical machine according to claim 11 is an embedded magnet comprising a rotor and a stator in which the rotor is supported in an internal space via a bearing and a coil is wound in its own slot. In the type rotating electric machine, the rotor according to claim 10 is used as the rotor.
According to a twelfth aspect of the present invention, the interior permanent magnet electric machine according to the eleventh aspect is used as a drive motor or a generator for driving wheels.
An elevator according to a thirteenth aspect is characterized in that the interior permanent magnet type electric rotating machine according to the eleventh aspect is used as a drive motor.
According to a fourteenth aspect of the present invention, the interior permanent magnet rotating electric machine according to the eleventh aspect is used as a drive motor.

According to invention of Claims 1-4, the rotor core of an embedded magnet type | mold rotary electric machine consists of a steel plate which has hardenability, such as laminated carbon steel and alloy steel, and the bridge | bridging part which restrict | limits the maximum rotational speed of a motor is provided. Since it is strengthened by the quenching process, high-speed rotation can be realized while maintaining low iron loss.
In addition, according to the invention of claim 5, since the steel sheet constituting the rotor core has a non-conductive compound layer by non-conductive film or surface treatment on each laminated surface to be laminated, Similarly, an increase in iron loss due to eddy current can be prevented.

According to the invention of claim 6, since the rotor core processes the steel sheet into a set shape and laminates and quenches, the steel sheet is soft in the shape processing step such as press forming, and the processing accuracy is reduced and the die A decrease in service life is not a problem. Also, because the magnet mounting hole is used to quench the bridge part that limits the maximum rotational speed of the rotor and the vicinity of the bridge part, the amount of heat required for the quenching process can be minimized, and the outer bridge part located on the outer periphery of the rotor Since the center bridge portion in the inner peripheral portion of the rotor can be quenched at the same time, the labor required for the processing can be reduced and the rotor core can be manufactured at low cost.
According to the seventh aspect of the present invention, since the flame is blown through the magnet mounting hole and the periphery of the magnet mounting hole including the bridge portion and the vicinity of the bridge portion is quenched, there is less labor required for the processing, and the rotor core can be manufactured at low cost. Can be manufactured.
Further, according to the invention described in claim 8, since the heated carburizing gas is passed through the magnet mounting hole and the gas carburizing and quenching treatment is performed around the magnet mounting hole including the bridge portion and the vicinity of the bridge portion, the labor required for the processing is also reduced. The rotor core can be manufactured at low cost at a low cost.
According to the ninth aspect of the present invention, since the laser torch is inserted into the magnet mounting hole and the bridge portion and the vicinity of the bridge portion are subjected to quenching treatment by heating with laser beam irradiation, the labor required for the treatment is reduced and the rotor core is inexpensive. Can be manufactured.
According to the invention described in claim 10, since the rotor is constituted by the rotor core according to any one of claims 1 to 5 and the magnet mounted in the magnet mounting hole of the rotor core, low iron High speed rotation can be realized while maintaining the loss.
Further, according to the invention described in claim 11, since the rotor described in claim 10 is used as the rotor, high-speed rotation can be realized while maintaining a low iron loss.
Further, according to the invention described in claims 12 to 14, by using the embedded magnet type rotating electrical machine described in claim 11 as a drive motor or generator capable of rotating at high speed with low loss, a vehicle, an elevator Improvement of energy consumption and efficiency in the processing machine can be realized.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a part of the shape of a rotor core of an embedded magnet type rotating electric machine according to the first embodiment of the present invention.
In FIG. 1, the rotor core 21 is provided with two magnet mounting holes 22 and 23 for mounting two magnets per pole. The outer periphery of the rotor 20 around the two magnet mounting holes 22 and 23 has an outer bridge portion 24 (part with a thick stripe pattern) and is sandwiched between the two magnet mounting holes 22 and 23 on the inner peripheral side. The center bridge portion 25 (part with a thick stripe pattern) is provided at the position. The bridge portion 26 and the vicinity 27 of the bridge portion around these two magnet mounting holes 22 and 23 are strengthened by a quenching process.
When the magnet 19 (see FIG. 3) is mounted in the magnet mounting holes 22 and 23, and the rotor 20 rotates at a high speed, the stress due to the centrifugal force is maximized in the bridge portions 24 and 25. Therefore, the maximum rotation speed of the rotor 20 Experiments have also confirmed that it is sufficient to improve the strength of the bridge portions 24 and 25 and increase the strength of other portions.
The rotor core 21 is made of a hardened steel plate such as a laminated carbon steel or alloy steel, and becomes a high strength steel plate having a strength limit of about 1600 MPa by the quenching process. Can be realized.

FIGS. 2A and 2B are views for explaining the rotor core 21 of the embedded magnet type rotating electric machine according to the first embodiment. FIG. 2A is an external perspective view, and FIG. 2B is a cross-sectional view of one steel plate.
In FIG. 2, the steel plate 21a which comprises the rotor core 21 has the nonelectroconductive compound layer 21b by a nonelectroconductive film | membrane or surface treatment in each lamination surface to laminate | stack. Therefore, an increase in iron loss due to eddy current can be prevented as in the case of conventional electromagnetic steel sheets.
The rotor core 21 is processed by quenching after the steel plate 21a is processed into a set shape and laminated. Therefore, the steel sheet is soft in the shape processing step such as press forming, and the reduction in processing accuracy and the reduction in mold life are not a problem.

FIG. 3 is a cross-sectional view of the rotor for an embedded magnet type rotating electrical machine showing the first embodiment, where (a) is a cross-sectional view in the axial direction, and (b) is a cross-sectional view in the direction perpendicular to the axis for one steel plate. .
In FIG. 3, the rotor 20 has a magnet 19 mounted in the magnet mounting holes 22 and 23 of the rotor core 21 shown in FIG. 2 and is fitted to the shaft 28, and the axial direction is adjusted by the load side plate 29L and the anti-load side plate 29C. It is fixed.
In the rotor 20 of this embodiment, the angle between two magnets per pole of the rotor core 21 is designed to be sufficiently narrow, and the magnetic flux generated from the magnet is concentrated on the rotor surface, so that the rotor core 21 is intentionally saturated with the magnetic flux. The iron loss of the rotor core 21 is kept low by reducing the change in magnetic flux density in the portion near the surface of the rotating rotor core 21.

FIG. 4 is a radial cross-sectional view of the interior magnet type rotating electric machine showing the first embodiment, and FIG. 5 is an axial cross-sectional view.
In both figures, the embedded magnet type rotating electrical machine has a rotor 20 in which a magnet 19 is mounted inside a rotor core 21, and a load side bearing 37 (FIG. 5) and an anti-load side bearing 38 (FIG. 5) installed on a shaft 28. 5), the load-side bracket 35 (FIG. 5) and the anti-load-side bracket 36 (FIG. 5) are rotatably held.
The stator 30 includes a stator core 31 and a stator coil 32, and is held by a frame 33. The frame 33 is fixed to a load side bracket by a fastening bolt 34 together with an anti-load side bracket. Energization of the stator coil 32 is performed through lead wires 39 (FIG. 5) of the stator coil 32, and an encoder unit 40 for detecting the rotational position is installed on the opposite side of the rotor 20.
The interior magnet type rotating electric machine having the rotor 20 of the present embodiment can achieve high speed rotation while maintaining low iron loss, and can achieve high output and high efficiency.

FIG. 6 shows a method for quenching the rotor core 21 according to the first embodiment.
In FIG. 6, the rotor core 21 is mounted between the inlet side wind guide jig 41 and the outlet side wind guide jig 42, and the flame is passed from the inlet side wind guide jig to the magnet mounting holes 22 and 23 of the rotor core 21. . The inlet side air guide jig 41 has a structure in which the flame passage is branched to the magnet mounting holes 22 and 23 of the rotor core 21 on the side in contact with the rotor core 21 so that the flame does not contact the portions other than the magnet mounting holes 22 and 23 as much as possible. ing. The same applies to the outlet side air guide jig 42.
The flame is an oxygen acetylene flame, passed through the magnet mounting holes 22 and 23, heated to 800-1000 ° C. above the quenching temperature of the steel sheet, and then naturally quenched using heat diffusion. The flame quenching is a quenching method suitable for local quenching such as the outer bridge portion 24, the center bridge portion 25 and the vicinity 26, 27 of the rotor core 21 shown in FIG. The amount of heat required for the quenching process can be minimized, and the outer bridge portion 24 on the outer peripheral portion of the rotor and the center bridge portion 25 on the inner peripheral portion of the rotor can be quenched at the same time. The rotor core 21 can be manufactured.
Since the rotor core 21 of the present embodiment has a relatively large heat capacity, it is naturally rapidly cooled using heat diffusion. However, the rotor core 21 having a relatively small heat capacity may be rapidly cooled through cooling air after heating by a flame. Alternatively, the temperature of the cooling air may be adjusted, the cooling speed may be precisely controlled, and the strengthening of the steel sheet by the quenching process may be adjusted to have more desired characteristics.

FIG. 7 is a process diagram of a method of manufacturing the rotor core 21 showing the first embodiment.
FIG. 7 summarizes the contents described with reference to FIG. 6.
First, the load side plate 29L is press-fitted into the shaft 28 (FIG. 3) and integrated.
On the other hand, the steel sheet is punched and laminated and integrated. The laminated steel sheet is flame-heated by the method of FIG. 6 according to the first embodiment and then cooled to finish the quenching process, and the rotor core 21 (FIG. 2) is completed.
After assembling the rotor core 21 to the shaft 28, the magnet 19 is inserted into the magnet mounting holes 22 and 23 and bonded and integrated, and the anti-load side plate 29C is press-fitted and integrated and magnetized. The rotor 20 (FIG. 3) is completed.

FIG. 8 shows a method for quenching the rotor core 21 according to the second embodiment of the present invention.
In FIG. 8, the rotor core 21 is mounted between the inlet side air guide jig 41 and the outlet side air guide jig 42, and the carburizing gas heated to a high temperature by the heater 44 is supplied to the inlet side air guide by the blower 43. The tool is passed through the magnet mounting holes 22 and 23 of the rotor core 21. The inlet side air guide jig 41 branches the carburizing gas passage into the magnet mounting holes 22 and 23 of the rotor core 21 on the side in contact with the rotor core 21, and the carburizing gas is in contact with the portions other than the magnet mounting holes 22 and 23 as much as possible. It is the same as in the first embodiment that the structure is not. The same applies to the outlet side air guide jig 42.
As the carburizing gas, propane gas or the like is heated to 900 to 1000 ° C. and passed through the magnet mounting holes 22 and 23 to perform carburizing and quenching. The carburizing quenching is a quenching method suitable for quenching the surface layer portion of the steel plate such as the outer bridge portion 24, the center bridge portion 25 and the vicinity 26, 27 of the rotor core 21 shown in FIG. Since the magnet mounting holes 22 and 23 including the bridge portions 24 and 25 and the vicinity of the bridge portions 26 and 27 can be quenched in a short time with a minimum amount of heat. The rotor core 21 can be manufactured at low cost at a low cost.
The difference between the second embodiment and the first embodiment is that the first embodiment uses high carbon steel while flame quenching is used, whereas the carburizing and quenching of the second embodiment uses low carbon steel.
In general, the low carbon steel has better hysteresis characteristics and lower iron loss than the magnetic steel sheet. On the contrary, the distortion due to the quenching process is large, and attention must be paid to the shape deformation of the rotor core 21.
As described in the first embodiment, when the design is such that the magnetic flux generated from the magnet cannot be sufficiently concentrated on the rotor surface, the iron loss increases depending on the hysteresis characteristics. According to this, only the surroundings of the magnet mounting holes 22 and 23 including the bridge portion and the vicinity of the bridge portion are reinforced, and the other portions can be stopped at a relatively low iron loss.
In addition, when it is desired to improve the corrosion resistance of the steel sheet surface, 0.5 to 1% ammonia may be added to the carburizing gas atmosphere to perform carbonitriding.

FIG. 9 is a process diagram of a method for manufacturing the rotor core 21 according to the second embodiment. The difference from the first embodiment of FIG. 7 is that the first embodiment is subjected to quenching treatment by cooling after flame heating. In contrast, the quenching process here is carburizing and quenching.
After assembling the rotor core 21 to the shaft 28, the magnet 19 is inserted into the magnet mounting holes 22 and 23 and bonded and integrated, and the anti-load side plate 29C is press-fitted and integrated and magnetized. The rotor 20 (FIG. 3) is completed.

FIG. 10 shows a method for quenching the rotor core 21 according to the third embodiment.
In the figure, a laser torch 45 is inserted into the magnet mounting holes 22 and 23, and the bridge portions 24 and 25 (FIG. 1) and the vicinity 26 and 27 (FIG. 1) of the bridge portion are quenched by heating by laser beam irradiation. The heat source guides the laser beam obtained from the YAG laser transmitter to the laser torch 45 by the optical cable 46. The optical cable 46 and the laser torch 45 are fixed to the torch stay 47, and the torch stay is moved and quenched while irradiating the laser beam from the magnet mounting holes 22 and 23 to the bridge portions 24 and 25 and the vicinity 26 and 27 of the bridge portion. I do.

FIG. 11 is a process diagram of a method of manufacturing a rotor core 21 showing a third embodiment of the present invention. The difference between the first embodiment shown in FIG. 7 and the second embodiment shown in FIG. This is a quenching process in which the steel is cooled after being heated. In the second embodiment, the quenching process is a carburizing quenching process, but here the quenching process is a quenching process by laser beam irradiation.
Then, after assembling the rotor core 21 to the shaft 28, the magnet 19 is inserted into the magnet mounting holes 22 and 23 and bonded and integrated, and the anti-load side plate 29C is press-fitted and integrated and magnetized. Thus, the rotor 20 (FIG. 3) is completed.

  The present invention is different from Patent Document 1 in that the steel plate having hardenability such as carbon steel or alloy steel is used instead of strengthening the electromagnetic steel plate by work hardening, and the bridge portion and the bridge portion around the magnet mounting holes 22 and 23 are used. This is a portion strengthened by quenching the vicinity.

  Since the embedded magnet type rotating electric machine of the present invention can be rotated at high speed while maintaining low iron loss, it is a driving motor or generator for a hybrid vehicle, a fuel cell vehicle, an electric vehicle, etc., and a drive for a railway vehicle. It is also effective as a generator used in motors, generators, and generator cars for uninterruptible power supplies. In addition to the above, general industrial machinery such as elevators, elevators in multilevel parking lots, fluid machinery such as compressors, blowers, and pumps for wind and hydraulic power, semiconductor manufacturing equipment, and processing machines mainly using machine tool spindles. It is also effective for driving motor applications.

It is a figure which shows a part of shape of the rotor core of the interior magnet type rotary electric machine which shows 1st Example of this invention. It is a figure explaining the rotor core of the embedded magnet type rotary electric machine which shows 1st Example, (a) is an external appearance perspective view, (b) is sectional drawing of one steel plate. It is sectional drawing of the rotor for embedded magnet type rotary electric machines which shows 1st Example, (a) is an axial sectional view, (b) is sectional drawing of an orthogonal direction with respect to an axis | shaft about one steel plate. It is radial direction sectional drawing of the interior magnet type rotary electric machine which shows 1st Example. It is an axial sectional view of the interior magnet type rotating electrical machine showing the first embodiment. It is a hardening method of a rotor core which shows a 1st example. It is process drawing of the manufacturing method of the rotor core which shows 1st Example. It is a hardening method of the rotor core which shows 2nd Example of this invention. It is process drawing of the manufacturing method of the rotor core which shows 2nd Example. It is a hardening method of a rotor core which shows the 3rd example of the present invention. It is process drawing of the manufacturing method of the rotor core which shows 3rd Example. It is an example of the rotor core of the conventional interior magnet type rotary electric machine.

Explanation of symbols

19 Magnet 20 Rotor 21 Rotor core 22, 23 Magnet mounting hole 24 Outer bridge portion 25 of rotor core Center bridge portion 26 of rotor core 27 Near outer bridge portion of rotor core 28 Near center bridge portion of rotor core 28 Shaft 29L Load side plate 29C Anti-load side Plate 30 Stator 31 Stator core 32 Stator coil 33 Frame 34 Fastening bolt 35 Load side bracket 36 Anti load side bracket 37 Load side bearing 38 Anti load side bearing 39 Stator coil lead wire 40 Encoder unit

Claims (14)

  A rotor core having a magnet mounting hole for mounting a magnet inside a rotor core formed by stacking steel plates, wherein the steel plate is a hardened steel plate, and the vicinity of the magnet mounting hole is quenched. .   The rotor core according to claim 1, wherein the steel plate having hardenability is carbon steel or alloy steel.   The rotor core according to claim 1, wherein a vicinity of the magnet mounting hole is a bridge portion around the magnet mounting hole and a vicinity of the bridge portion.   2. The rotor core according to claim 1, wherein the magnet mounting hole has a V shape having a vertex at the center side of the rotor for each pole.   2. The rotor core according to claim 1, wherein each of the steel plates has a non-conductive film or a non-conductive compound layer formed by a surface treatment on a laminated surface.   In the method of manufacturing a rotor core having a magnet mounting hole for mounting a magnet inside a rotor core formed by stacking hardened steel plates, the rotor core is hardened by processing the steel plates into a set shape and then stacking the magnets A method of manufacturing a rotor core, characterized by quenching only in the vicinity of the magnet mounting hole by using a hole.   The rotor core manufacturing method according to claim 6, wherein the hardening process of the rotor core is performed by blowing a flame through the magnet mounting hole to quench the magnet mounting hole including the bridge portion and the vicinity of the bridge portion. .   7. The hardening process of the rotor core is characterized in that a gas carburizing and quenching process is performed around the magnet mounting hole including the bridge portion and the vicinity of the bridge portion by passing a carburized gas heated to the magnet mounting hole. Rotor core manufacturing method.   7. The method of manufacturing a rotor core according to claim 6, wherein the hardening process of the rotor core includes a laser torch inserted into the magnet mounting hole, and the bridge part and the vicinity of the bridge part are hardened by heating by laser beam irradiation.   A rotor comprising: the rotor core according to any one of claims 1 to 5; and a magnet mounted in the magnet mounting hole of the rotor core. In an embedded magnet type rotating electrical machine comprising a rotor and a stator that supports the rotor in an internal space via a bearing and winds a coil in its own slot,
An embedded magnet type rotary electric machine using the rotor according to claim 10 as the rotor.   12. A vehicle using the interior magnet type rotating electric machine according to claim 11 as a driving motor or a generator for driving wheels.   An elevator using the interior magnet type rotating electric machine according to claim 11 as a drive motor.   12. A processing machine using the embedded magnet type rotating electric machine according to claim 11 as a drive motor.

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