Paste containing a non-magnetic modification source, non-magnetic device, rotor core, and method for manufacturing the same.

Abstract

The present invention provides a rotor core that can perform demagnetic modification of the bridge portion more sufficiently and stably than conventional methods, and that has superior centrifugal strength of the bridge portion. [Solution] The rotor core of the present invention is a rotor core in which electromagnetic steel sheets 18 made of Fe-Si alloy are laminated, and the electromagnetic steel sheets 18 have bridge portions 14 containing Fe-Si-Mn-C alloy that have been demagnetically modified with a paste containing a demagnetic modification source which includes manganese powder, which is a demagnetic modification source, and a resin ink containing a component that can be carbonized by heating.

Description

Technical Field

[0001] The present invention relates to a demagnetization modification source-containing paste, a demagnetization apparatus, a rotor core, and a method for manufacturing the same.

Background Art

[0002] In recent years, efforts toward realizing a low-carbon society or a decarbonized society have intensified, and research and development on electric vehicles that travel using rotational power of rotating electrical machines is being carried out to reduce CO₂ emissions and improve energy efficiency even in vehicles. Conventionally, as a rotor core for a rotating electrical machine, one having a bridge portion (also referred to as a reinforcing rib) around a permanent magnet accommodation hole is known (for example, see Patent Document 1). The bridge portion enhances the centrifugal strength of the rotor core when the rotor rotates. Further, the bridge portion is subjected to a demagnetization modification treatment. Specifically, laser light is irradiated onto the modifying metal powder that is sprayed and adhered to the surface of the bridge portion, so that the metal component of the bridge portion and the modifying metal powder are alloyed. This suppresses the occurrence of leakage magnetic flux in the bridge portion when the rotor rotates. A rotating electrical machine provided with this rotor core can prevent a decrease in efficiency.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of Invention

Problems to be Solved by the Invention

[0004] However, since demagnetization of the bridge portion in a conventional rotor core (for example, see Patent Document 1) is performed by alloying the modifying metal powder adhered to the surface of the bridge portion and the metal component of the bridge portion, there is a problem that demagnetization of the bridge portion cannot be performed sufficiently and stably. Furthermore, while it is desirable to form the bridge portion of the rotor core thinly in order to reduce the recirculating magnetic flux during rotor rotation, there is a problem in that if the bridge portion becomes thin, it becomes impossible to secure the necessary centrifugal strength.

[0005] Therefore, the object of the present invention is to provide a paste containing a non-magnetic modification source, a non-magnetic modification device, a rotor core, and a method for manufacturing the same, which can perform non-magnetic modification of the bridge portion more sufficiently and stably than conventional methods, and can also produce a rotor core with superior centrifugal strength of the bridge portion. This will ultimately contribute to improving energy efficiency. [Means for solving the problem]

[0006] The first aspect of the present invention, which solves the aforementioned problems, is a paste containing a non-magnetic modification source that is required to be melted in a subsequent process in areas of an electrical steel sheet where non-magnetic modification is necessary, and is characterized by containing manganese powder as a non-magnetic modification source and a resin ink containing a component that can be carbonized by heating.

[0007] The second aspect of the present invention, which solves the aforementioned problems, is a demagnetizing device for demagnetizing a plurality of specific areas formed by applying the demagnetizing modification source-containing paste to a plurality of locations on an electrical steel sheet that requires demagnetizing modification, by heating and melting each of these specific areas, the device comprising: a laser beam irradiation means for heating and melting a plurality of specific areas by changing the laser beam irradiation position to correspond to the plurality of specific areas; and a control unit for controlling the laser beam irradiation position by the laser beam irradiation means, wherein the control unit divides the plurality of locations on the electrical steel sheet that require demagnetizing modification into a plurality of groups and controls the laser beam irradiation position so that the timing of heating and melting does not overlap between the groups.

[0008] Furthermore, a third aspect of the present invention that solves the above problems is a rotor core in which electromagnetic steel sheets made of Fe-Si alloy are laminated with an insulating coating in between, characterized in that the electromagnetic steel sheets have a bridge portion containing Fe-Si-Mn-C alloy which has been demagnetically modified with the demagnetic modification source-containing paste described in claim 1.

[0009] Furthermore, a fourth aspect of the present invention, which solves the above-mentioned problems, is a method for manufacturing a rotor core using the above-mentioned paste containing a non-magnetic modification source, characterized by comprising: a step of applying the paste containing a non-magnetic modification source to multiple locations on an electrical steel sheet that requires non-magnetic modification; and a step of non-magnetic modification of the electrical steel sheet, in which the multiple locations on the electrical steel sheet to which the paste containing a non-magnetic modification source has been applied are divided into multiple groups, and the multiple locations are heated and melted so that the timing of heating and melting does not overlap among the groups, and then solidified. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a paste containing a non-magnetic modification source, a non-magnetic modification device, a rotor core, and a method for manufacturing the same, which can perform non-magnetic modification of the bridge portion more sufficiently and stably than in the conventional method, and can also obtain a rotor core with excellent centrifugal strength of the bridge portion. [Brief explanation of the drawing]

[0011] [Figure 1] This is a diagram illustrating the configuration of a rotating electric machine equipped with a rotor core according to an embodiment of the present invention. [Figure 2] This is a partial perspective view of an electromagnetic steel sheet constituting a rotor core according to an embodiment of the present invention. [Figure 3] This is a manufacturing process diagram of a rotor core according to an embodiment of the present invention. [Figure 4] Figure 3 is an explanatory diagram of the application process of the paste containing the non-magnetic modification source. [Figure 5] Figure 3 is a schematic diagram showing how multiple blocks formed by applying a paste containing a non-magnetic modification source to an electrical steel sheet are divided into multiple groups during the non-magnetic modification process. [Figure 6] Figure 3 is a schematic diagram showing the partial irradiation of an electrical steel sheet coated with a paste containing a non-magnetic modification source by laser light during the demagnetic modification process of the electrical steel sheet. [Figure 7] This is an explanatory diagram of the configuration of a non-magnetic device according to an embodiment of the present invention. [Figure 8] This is a schematic diagram showing the irradiation trajectory of a laser beam on an electrical steel sheet. [Figure 9] This is an explanatory diagram of the compression insulation treatment step shown in FIG. 3. [Figure 10] This is an explanatory diagram of the punching and in-die lamination step shown in FIG. 3. [Figure 11] This is a graph showing the relationship between the ratio (%) of the ferromagnetic phase in the non-magnetization modified portion of the electrical steel sheet, the carbon [C] concentration (wt%), and the manganese [Mn] concentration (wt%). [Mode for Carrying Out the Invention]

[0012] Next, embodiments for carrying out the present invention (embodiments) will be described in detail with appropriate reference to the drawings. The non-magnetization modifying source-containing paste according to the present embodiment is used for manufacturing a rotor core constituting a rotating electrical machine, and is used for non-magnetization modification of the bridge portion of the electrical steel sheet forming the rotor core. In the following, first, the rotor core of the rotating electrical machine will be described, and then the method for manufacturing the rotor core, the non-magnetization modifying source-containing paste used in this manufacturing method, and the non-magnetization apparatus will be described.

[0013] <Rotor Core> FIG. 1 is a configuration explanatory view of a rotating electrical machine 10 including a rotor core 13 according to the present embodiment, and is a cross-sectional view of the rotating electrical machine 10 perpendicular to the axis of the rotating electrical machine 10. The rotating electrical machine 10 is assumed to be mounted on a hybrid vehicle or an electric vehicle and used as a motor for driving the vehicle, but can also be used for various other applications. As shown in FIG. 1, the rotating electrical machine 10 includes a cylindrical rotor 11 and an annular stator 21.

[0014] The rotor 11 is arranged on the inner peripheral side of the stator 21 so as to be coaxial with the rotor 11. As a result, the outer peripheral surface of the rotor 11 has a slight gap with respect to the inner peripheral surface of the stator 21. The rotor 11 is configured to be rotatable on the inner peripheral side of the stator 21 around a rotor shaft 20 integrated with the rotor 11. In the rotor core 13 constituting the rotor 11, permanent magnets 17 made of a neodymium magnet or the like are arranged. A plurality of the permanent magnets 17 are arranged along the circumferential direction on the outer peripheral side of the rotor core 13. The permanent magnet 17 is a rod-shaped body having a rectangular cross section, and extends in the axial direction of the rotor core 13 (the direction perpendicular to the paper surface of FIG. 1).

[0015] Specifically, three of the permanent magnets 17 form one set and are arranged at equal intervals in the circumferential direction. The three permanent magnets 17 constituting this set form a substantially V-shape opening radially outward, in the cross-sectional view shown in FIG. 1, by the permanent magnet 17a located at the center in the circumferential direction and a pair of permanent magnets 17b, 17b arranged so as to sandwich the central permanent magnet 17a in the circumferential direction. That is, among the three permanent magnets 17, the pair of permanent magnets 17b, 17b are arranged so as to be close to the outer peripheral surface of the rotor core 13, and the central permanent magnet 17a is displaced radially inward relative to the pair of permanent magnets 17b, 17b.

[0016] The three permanent magnets 17 constituting the set are attached to the rotor core 13 by being inserted into magnet accommodation holes 15a, 15b, 15b formed in the rotor core 13 so as to correspond to the positions of the respective permanent magnets 17a, 17b, 17b. The rotor core 13 as described above is configured by laminating a plurality of electromagnetic steel sheets 18 having a planar shape corresponding to the planar shape of the rotor core 13 in the axial direction of the rotary electric machine 10. The electromagnetic steel sheet 18 is punched out from an electromagnetic steel sheet 22 (see FIG. 3) described later so as to correspond to the planar shape of the rotor core 13. The electromagnetic steel sheet 18 in the present embodiment is preferably made of an Fe-Si alloy. The thickness of the electromagnetic steel sheet 18 is preferably 0.1 mm or more and 0.5 mm or less.

[0017] In Figure 1, reference numeral 23 denotes the stator core of the stator 21, reference numeral 24 denotes the yoke of the stator 21, and reference numeral 27 denotes a coil placed in the slot 26 so as to wind the teeth 25 of the stator 21.

[0018] Figure 2 is a partial perspective view of the electromagnetic steel sheet 18 that constitutes the rotor core 13 (see Figure 1). For ease of drawing, Figure 2 shows an enlarged view of the portion to which the three permanent magnets 17 (see Figure 1) that make up the set are attached. In Figure 2, reference numeral 20a denotes a mounting hole formed on the inner circumference side of the electromagnetic steel sheet 18 to which the rotor shaft 20 (see Figure 1) is attached.

[0019] As shown in Figure 2, three magnet housing holes 15a, 15b, and 15b are formed on the outer circumference of the electromagnetic steel sheet 18, corresponding to the three permanent magnets 17a, 17b, and 17b (see Figure 1) that form a set. In other words, as shown in Figure 2, the magnet housing holes 15a, 15b, and 15b form a roughly V shape that opens radially outward, with the magnet housing hole 15a located in the center in the circumferential direction and the pair of magnet housing holes 15b, 15b arranged to sandwich the central magnet housing hole 15a in the circumferential direction.

[0020] Furthermore, the electromagnetic steel sheet 18 has a bridge portion 14 that connects the outer core portion 13a and the inner core portion 13b. In Figure 2, the bridge portion 14 is shaded for ease of drawing. As shown in Figure 2, the bridge portion 14 includes an inner bridge portion 14a formed between the magnet housing hole 15a and the magnet housing hole 15b, and an outer bridge portion 14b formed between the outermost edge of the magnet housing hole 15b and the outer edge of the electromagnetic steel sheet 18.

[0021] These bridge portions 14 have reduced magnetic permeability compared to the general portion 18a of the electrical steel sheet 18. The magnetic permeability of the bridge portions 14 is reduced (demagnetized) by alloying with the metal component (modification source) contained in the demagnetizing modification source-containing paste, which will be described next. Specifically, the bridge portion 14 contains an Fe-Si-Mn-C alloy. Furthermore, the concentration (weight %) of carbon [C] in the bridge portion 14 is preferably 0.1% by weight or more, and more preferably 0.2% by weight or more. Also, the concentration (weight %) of manganese [Mn] in the bridge portion 14 is preferably 10% by weight or more, and more preferably 15% by weight or more.

[0022] The bridge section 14, set to such a range of carbon [C] concentration (weight %) and manganese [Mn] concentration (weight %), has sufficiently reduced magnetic permeability (becomes non-magnetic) and is also rich in centrifugal strength. In Figure 2, reference numeral 16 denotes an insulating coating formed on both sides of the electromagnetic steel sheet 18 at a nanometer to micrometer level. In this embodiment, the insulating coating 16 is assumed to be pre-formed on the electromagnetic steel sheet 22 (see Figure 4), which will be the raw material for the electromagnetic steel sheet 18.

[0023] <Manufacturing method for rotor cores> Next, we will explain the manufacturing method of the rotor core 13 (see Figure 1). Figure 3 is a manufacturing process diagram for the rotor core 13 (see Figure 1). As shown in Figure 3, this manufacturing method includes a step of applying a paste containing a non-magnetic modifying source to an electromagnetic steel sheet 22 (see Figure 4) as described later (step S101), a step of demagneticizing and modifying the electromagnetic steel sheet 22 (see Figure 4) (step S102), a step of compression insulation treatment of the demagnetically modified electromagnetic steel sheet 22 (see Figure 4) (step S103), and a step of punching and in-die lamination in which an electromagnetic steel sheet 18 (see Figure 2) is punched out from the electromagnetic steel sheet 22 (see Figure 4) and laminated (step S104).

[0024] Figure 4 is an explanatory diagram of the application process (step S101) of the paste containing the non-magnetic modification source shown in Figure 3. Hereafter, the paste containing the non-magnetic modification source may be simply referred to as "paste". In this coating process, as shown in Figure 4, paste 5 is applied to the surface of the electromagnetic steel sheet 22, which will serve as the raw material for the electromagnetic steel sheet 18 (see Figure 2).

[0025] Now, let's explain Paste 5. The paste 5 of this embodiment contains manganese powder, which is a non-magnetic modification source, a resin ink, a thixotropic agent, and an organic solvent. The manganese powder consists of metallic manganese, and the sieve components with a mesh size of 75 μm in accordance with JIS Z8801 can be used. Preferably, the median diameter (D50) determined by laser diffraction / scattering is about 10 μm. However, the manganese powder is not limited to these. The manganese powder content in paste 5 is preferably 85.0 to 95.0% by weight.

[0026] Examples of resin inks include, but are not limited to, cellulosic polymers such as ethylcellulose and hydroxyethylcellulose, acrylic resins such as polybutyl methacrylate, polymethyl methacrylate, and polyethyl methacrylate, epoxy resins, phenolic resins, alkyd resins, and organic binders such as polyvinyl alcohol and polyvinyl butyral. Among these, acrylic resins are preferred. The resin ink functions as a component that binds the manganese powder together in paste 5 to form a paste, and also functions as a carbon source for carbon atoms that are diffused into the electromagnetic steel sheet 22 (see Figure 4) in the demagnetic modification step S102 (see Figure 3) described later. The resin ink content in paste 5 is preferably 0.3 to 1.0% by weight.

[0027] Examples of thixotropic agents include, but are not limited to, organic thixotropic agents such as hydrogenated castor oil and stearic acid amide. In this embodiment, the thixotropic agent imparts shape retention to the applied paste containing the non-magnetic modification source in the application process of paste 5 to the electrical steel sheet (see Figure 7), which will be described later. The thixotropic agent also functions as a carbon source for carbon atoms diffused into the electrical steel sheet in the non-magnetic modification process (see Figure 7), which will be described later. The preferred content of the thixotropic agent in paste 5 is 0.5 to 1.5% by weight.

[0028] Examples of organic solvents include, but are not limited to, ester-based solvents such as butyl cellosolve acetate and butyl carbitol acetate (BCA: diethylene glycol monobutyl ether acetate), ether-based solvents such as butyl carbitol (BC: diethylene glycol monobutyl ether), ethylene glycol, diethylene glycol derivatives, toluene, xylene, mineral spirits, terpineol, and menthol. Among these, butyl carbitol is preferred.

[0029] The organic solvent imparts fluidity to the paste 5 and also functions as a carbon source for the carbon atoms that will be diffused into the electrical steel sheet in the demagnetic modification process described later (see Figure 7). The preferred content of the organic solvent in paste 5 is 2.5 to 15.0% by weight. Paste 5 can be prepared by mixing the above-mentioned components.

[0030] Returning to Figure 4, in the paste application process (step S101 in Figure 3), the paste 5 is applied as tiny rectangular blocks B to multiple specific areas of the electrical steel sheet 22 that correspond to the bridge portion 14 (see Figure 2) of the electrical steel sheet 18 (see Figure 2) that requires demagnetization modification. Block B has a rectangular plane that encloses the bridge portion 14 (see Figure 2). Furthermore, the thickness of block B is 0.25 mm or more, so that the manganese concentration in paste 5 is 30% or more by weight relative to the bridge portion 14 (see Figure 2), as will be explained in detail later.

[0031] As shown in Figure 4, these blocks B form a group of blocks arranged circumferentially, corresponding to multiple bridge portions 14 (see Figure 2) on a single electrical steel sheet 18 (see Figure 2). These groups of blocks B form the application pattern P of the paste 5. In this embodiment, the application pattern P of the paste 5 is arranged in two rows in the width direction of the electromagnetic steel sheet 22, and continuously in a staggered pattern of 60 degrees in the longitudinal direction of the electromagnetic steel sheet 22.

[0032] In this embodiment, the application of paste 5 is assumed to be performed using a cylindrical rotating body 31 having multiple through holes H on its circumferential surface corresponding to the application pattern P, as shown in Figure 4. Specifically, in this application method, paste 5 is supplied to the inside of a rotating body 31 that rotates synchronously while in contact with the electrical steel sheet 22 being conveyed at a feed speed V1. On the surface of the electrical steel sheet 22, the application pattern P is formed continuously in the longitudinal direction of the electrical steel sheet 22 by the paste 5 extruded from the through holes H of the rotating body 31.

[0033] In the demagnetization modification process (step S102) shown in Figure 3, laser light is irradiated onto each block B (see Figure 4) that forms the coating pattern P (see Figure 4). This heats and melts the metal components forming the electromagnetic steel sheet 22 and the manganese powder contained in the paste 5, forming an Fe-Si-Mn alloy. The electromagnetic steel sheet 22 in the areas where the paste 5 was applied undergoes demagnetization modification, and its magnetic permeability decreases.

[0034] Furthermore, in the demagnetic modification process (step S102), the resin ink contained in the paste 5 is fired by irradiation with laser light. The carbon atoms produced by the carbonization of the fired resin ink diffuse into the electrical steel sheet 22 to form an Fe-Si-Mn-C alloy. The Fe-Si-Mn-C alloy increases the hardness of the electrical steel sheet 22 in the areas where the paste 5 was applied, thereby increasing the strength of the electrical steel sheet 22 in the areas where the bridge portion 14 is formed.

[0035] In this embodiment, during the demagnetization modification process, the multiple blocks B formed by applying paste 5 are divided into multiple groups, and each divided group is irradiated with laser light.

[0036] Figure 5 is a schematic diagram showing how multiple blocks B formed by applying paste 5 are divided into multiple groups I, II, and III. As shown in Figure 5, the multiple blocks B that make up the application pattern P of paste 5 are divided into six groups.

[0037] Specifically, the blocks B that make up the coating pattern P are divided into three groups: Group I (two blocks per group), Group II (two blocks per group), and Group III (two blocks per group). Furthermore, the groups I forming a set, the groups II forming a set, and the groups III forming a set are facing each other with the center of the coating pattern P in between. In this embodiment, one group of Block B corresponds to two sets of bridge sections 14a, 14b, and 14b shown in Figure 2.

[0038] Figure 6 is a schematic diagram showing the partial irradiation of a laser beam onto an electrical steel sheet 22 coated with paste 5 during the demagnetization modification process. In Figure 6, the white block B represents the area not irradiated by the laser light, and the black block B represents the area irradiated by the laser light. Also in Figure 6, the symbols I, II, and III represent the group to which block B belongs. The symbols 42a, 42b, and 42c are dashed lines (double-dotted lines) that indicate the position of the laser light irradiation means in the demagnetization device 40 (see Figure 7), which will be described later. As shown in Figure 6, in the demagnetization modification process, the irradiation timing of the laser beams from the laser beam irradiation means 42a, 42b, and 42c for each group I, II, and III is set so that groups I, II, and III do not overlap with each other.

[0039] Here, we will describe the demagnetization apparatus according to this embodiment used in the demagnetization modification process. Figure 7 is an explanatory diagram of the configuration of the demagnetization device 40 according to this embodiment. As shown in Figure 7, the demagnetizing device 40 includes a transport means 41 for transporting the electromagnetic steel sheet 22, a laser beam irradiation means 42 for irradiating the electromagnetic steel sheet 22 with laser light, and a control unit 43 for controlling the laser beam irradiation position and laser beam irradiation timing by the laser beam irradiation means 42.

[0040] In this embodiment, the conveying means 41 is assumed to consist of two pairs of rollers 41a and 41b that rotate while gripping the electromagnetic steel sheet 22. The two pairs of rollers 41a and 41b are arranged at a predetermined distance from each other in the direction of transport of the electrical steel sheet 22. The pair of rollers 41a positioned downstream in the conveying direction of the electrical steel sheet 22 are drive rollers and intermittently convey the electrical steel sheet 22 in accordance with commands from the control unit 43. The pair of rollers 41b positioned upstream in the conveying direction are driven rollers and apply a predetermined tension to the electrical steel sheet 22 conveyed by the pair of rollers 41a.

[0041] In this embodiment, the laser beam irradiation means 42 is assumed to be a fiber laser with a scanner function. Multiple laser beam irradiation means 42 are arranged between the roller pair 41a and the roller pair 41b. Specifically, as shown in Figure 5, three laser beam irradiation means 42 are arranged in a line in the direction of transport of the electromagnetic steel sheet 22.

[0042] Each of these three laser irradiation means 42a, 42b, and 42c has a different laser irradiation position relative to the application pattern P (see Figure 4) of the paste 5 (see Figure 4) on the conveyed electromagnetic steel sheet 22. Specifically, as shown in Figure 6, the transport means 41 stops transporting the electromagnetic steel sheet 22 so that the coating pattern P of the electromagnetic steel sheet 22 is positioned relative to the laser beam irradiation means 42a, 42b, and 42c at predetermined positions. Then, by scanning, the laser beam irradiation means 42a irradiates only block B belonging to group I of the two sets of coating patterns P that the laser beam irradiation means 42a is positioned across.

[0043] Furthermore, the laser beam irradiation means 42b irradiates only block B belonging to group II of the two sets of coating patterns P across which the laser beam irradiation means 42b is positioned, by scanning. Furthermore, by scanning, the laser beam irradiation means 42c irradiates only block B, which belongs to group III of the two sets of coating patterns P across which the laser beam irradiation means 42c is positioned, with laser light.

[0044] In Figure 6, block B of group I adjacent to group II, where laser beam irradiation means 42b irradiates with laser beam, is the portion irradiated by laser beam irradiation means 42a in the previous step. Also in Figure 6, block B of group II adjacent to group III, where laser beam irradiation means 42c irradiates with laser beam, is the portion irradiated by laser beam irradiation means 42b in the previous step. Furthermore, in Figure 6, block B of group I adjacent to group III, where laser beam irradiation means 42c irradiates with laser beam, is the portion irradiated by laser beam irradiation means 42a in an even earlier step. In other words, in the demagnetizing device 40, the transport means 41 intermittently transports the electromagnetic steel sheets 22 at predetermined intervals, so that the laser light irradiation means 42a, 42b, and 42c irradiate all the coating patterns P with laser light.

[0045] The endpoint of the laser beam irradiation by the laser beam irradiation means 42a, 42b, and 42c is set outside the forming portion of the bridge portion 14, preferably outside block B. Figure 8 is a schematic diagram showing the irradiation trajectory Tr of the laser beam onto the electromagnetic steel sheet 22. In Figure 8, the symbol B represents a block, and the symbol 22a represents the portion that is trimmed after irradiation with the laser beam to form magnet housing holes 15a, 15b, 15b, etc.

[0046] In Figure 8, as shown by the laser beam's irradiation trajectory Tr, the laser beam is irradiated so as to diagonally cross the rectangular block B and also so as to outline the contour of block B. Furthermore, when the laser beam is irradiated onto block B in such an elliptical manner as the laser beam's irradiation trajectory Tr, the starting point Sp and ending point Ep of the laser beam irradiation are set on the electrical steel plate 22a on the outside of block B. Incidentally, in the example shown in Figure 8, the starting point Sp and ending point Ep coincide, but the starting point Sp and ending point Ep can also be set to different positions. By irradiating with laser light in this manner, it is possible to prevent the formation of laser marks such as cracks and craters on the electromagnetic steel sheet 18 (see Figure 2), which tend to occur at the starting point Sp and ending point Ep of the laser light irradiation.

[0047] Returning to Figure 7, the control unit 43 of the demagnetization device 40 controls the operation of the transport means 41 and the timing of laser beam irradiation by the laser beam irradiation means 42a, 42b, and 42c so that the irradiation of laser beams does not overlap between groups I, II, and III. Such a control unit 43 can be configured to include a ROM (Read Only Memory) for storing a predetermined program, a RAM (Random Access Memory) for reading and expanding the program stored in the ROM, and a CPU (Central Processing Unit) for executing the expanded program and outputting commands to the laser beam irradiation means 42a, 42b, 42c and the transport means 41.

[0048] Next, the compression insulation process (step S103) shown in Figure 3 will be explained. Figure 9 is an explanatory diagram of the compression insulation process. As shown in Figure 9, in the portion 22b of the electromagnetic steel sheet 22 that has undergone demagnetization modification, the insulating coating 16 is removed and the portion expands. In the compression insulation process, portion 22b is sandwiched between a pair of punches 44 to make the thickness of portion 22b less than or equal to the thickness of the general portion of the electromagnetic steel sheet 22, preferably less than the thickness of the electromagnetic steel sheet 22. According to this compression insulation process, the expanded portion 22b is compressed, thereby forming an insulating space when the electromagnetic steel sheets 18 (see Figure 2) are laminated.

[0049] Next, we will explain the punching and in-die lamination process (step S104) shown in Figure 3. Figure 10 is an explanatory diagram of the punching and in-die lamination process. As shown in Figure 10, in the punching and in-die lamination process, the electromagnetic steel sheet 22 is punched out by the punching and lamination device 45 into a shape corresponding to the planar shape of the rotor core 13 (see Figure 1). At this time, as shown in Figure 2, a bridge portion 14 and magnet housing holes 15a, 15b, 15b are formed in the electromagnetic steel sheet 22. That is, of the non-magnetic modified portion formed by laser irradiation, the portion other than the bridge portion 14 (see Figure 2) is trimmed off. Then, the electromagnetic steel sheets 18 punched out from the electromagnetic steel sheet 22 (see Figure 10) are stacked and crimped within a predetermined mold, and if necessary, the stacked rotor core 13 is formed with adhesive or the like, integrating the electromagnetic steel sheets 18, thus completing the punching and in-die stacking process (step S104). This completes the rotor core 13 of this embodiment.

[0050] <Effects> Next, the effects and benefits of the paste 5 (paste containing a non-magnetic modification source), the non-magnetic device 40, the rotor core 13, and the manufacturing method thereof according to this embodiment will be described. The paste 5 according to this embodiment is a paste containing a non-magnetic modification source that needs to be melted in a later process in the area of ​​the electromagnetic steel sheet 2 where non-magnetic modification is required, and is characterized by containing manganese powder as the non-magnetic modification source and a resin ink containing a component that can be carbonized by heating. With such paste 5 (paste containing a demagnetic modification source), an Fe-Si-Mn-C alloy can be formed in the areas of the electrical steel sheet 2 where demagnetic modification is required (the parts corresponding to the bridge portion 14). As a result, the parts corresponding to the bridge portion 14 are demagnetic, reducing their magnetic permeability and improving their strength.

[0051] Furthermore, unlike conventional methods that only attach metal powder to the bridge portion (see, for example, Patent Document 1), this paste 5 (paste containing a non-magnetic modification source) can maintain contact between the non-magnetic modification source and the electrical steel sheet 22 for a long period of time. In addition, this paste 5 (paste containing a non-magnetic modification source) can accurately maintain the amount of the non-magnetic modification source in the areas of the electrical steel sheet 22 where non-magnetic modification is required. As a result, the paste 5 (paste containing a non-magnetic modification source) of this embodiment can perform the non-magnetic treatment of the bridge portion 14 more easily and quickly than conventional methods, and can also sufficiently and stably reduce the magnetic permeability of the bridge portion 14.

[0052] The demagnetizing apparatus 40 according to this embodiment is a demagnetizing apparatus that demagnetizes each of a plurality of blocks B (specific areas) formed by applying paste 5 to a plurality of locations on an electromagnetic steel sheet 22 that requires demagnetizing modification by heating and melting them, and comprises a laser beam irradiation means 42 that changes the laser beam irradiation position to correspond to the plurality of specific areas and heats and melts the plurality of specific areas, and a control unit 43 that controls the laser beam irradiation position by the laser beam irradiation means 42, wherein the control unit 43 divides the plurality of locations on the electromagnetic steel sheet 22 that require demagnetizing modification into a plurality of groups I, II, and III and controls the laser beam irradiation position so that the timing of heating and melting does not overlap between groups I, II, and III.

[0053] According to this demagnetization device 40, the areas requiring demagnetization modification are divided into multiple groups I, II, and III, and gradually converted into Fe-Si-Mn-C alloys. This reduces residual stress in the demagnetized modified areas. The demagnetization device 40 makes it possible to efficiently form demagnetized modified areas with very few defects such as cracks.

[0054] Furthermore, the rotor core 13 according to this embodiment is a rotor core 13 in which electromagnetic steel sheets 18 made of Fe-Si alloy are laminated with an insulating coating 16 in between, and the electromagnetic steel sheets 18 have bridge portions 14 containing Fe-Si-Mn-C alloy which have been demagnetically modified with paste 5. With such a rotor core 13, it is possible to construct a rotating electric machine that achieves both the non-magnetic nature of the bridge section 14 and improved centrifugal strength of the rotor.

[0055] Furthermore, in such a rotor core 13, it is desirable that the concentration of carbon [C] in the bridge portion 14 is 0.1% by weight or more, and the concentration of manganese [Mn] is 10% by weight or more. This rotor core 13 makes it possible to more reliably achieve non-magnetic properties of the bridge section 14 and improved centrifugal strength of the rotor.

[0056] Furthermore, the method for manufacturing the rotor core 13 according to this embodiment is a method for manufacturing the rotor core 13 using paste 5, and is characterized by comprising: a step of applying paste 5 to multiple locations on an electromagnetic steel sheet 22 that requires demagnetization modification; and a demagnetization modification step of the electromagnetic steel sheet 22 in which multiple blocks B (multiple locations) of the electromagnetic steel sheet 22 to which paste 5 has been applied are divided into groups I, II, and III, and the multiple blocks B are heated and melted so that the timing of heating and melting does not overlap among groups I, II, and III, and then solidified.

[0057] According to this method for manufacturing the rotor core 13, unlike conventional manufacturing methods (see, for example, Patent Document 1), it is possible to easily and quickly and efficiently perform demagnetization modification on the electrical steel sheet 22 without generating sputter when applying the demagnetization modification source to the electrical steel sheet 22.

[0058] Although this embodiment has been described above, the present invention is not limited to the above embodiment and can be implemented in various forms. [Examples]

[0059] Next, an example of the method for manufacturing the rotor core 13 according to the present invention will be described. In this embodiment, the optimal range of carbon [C] concentration and manganese [Mn] concentration in the non-magnetic modified portion of the electromagnetic steel sheet 18 constituting the rotor core 13 was investigated. In this example, paste 5 was prepared containing 90% by weight of manganese powder, 5% by weight of acrylic resin as a resin ink, 1% by weight of an organic thixotropic agent, and 4% by weight of an organic solvent.

[0060] Next, test specimens were prepared by applying paste 5 to the surface of a 0.3 mm thick Fe-Si alloy electrical steel sheet. Twenty different test specimens were prepared, each with paste 5 applied in a thickness ranging from 0.16 mm to 0.36 mm.

[0061] Next, laser light was irradiated onto the paste 5 applied to these 20 types of test pieces to partially demagnetize and modify the test pieces made of electromagnetic steel sheets. For the non-magnetic modified portion, the relationship between the ratio (volume %) of the ferromagnetic phase, the concentration (weight %) of carbon [C], and the concentration (weight %) of manganese [Mn] was determined. The proportion of the ferromagnetic phase was determined by measuring the volume fraction of the α-Fe phase using X-ray diffraction. The concentration (weight %) of carbon [C] was measured by infrared absorption spectroscopy of carbon contained in the combustion gas in the oxygen stream of the non-magnetic modification section. The concentration (weight %) of manganese [Mn] was measured by ICP emission spectroscopy. The results are shown in Figure 11.

[0062] Figure 11 is a graph showing the relationship between the ratio (volume %) of the ferromagnetic phase in the non-magnetic modified section, the concentration (weight %) of carbon [C], and the concentration (weight %) of manganese [Mn]. As shown in Figure 11, it was verified that by setting the carbon [C] concentration (weight%) of the demagnetizing modified portion to 0.1% by weight or more, preferably 0.2% by weight or more, and the manganese [Mn] concentration (weight%) to 10% by weight or more, preferably 15% by weight or more, the electrical steel sheet of the test piece undergoes sufficient demagnetizing modification, and the permeability of the demagnetized portion of the electrical steel sheet can be set within a suitable range.

[0063] Incidentally, in the example shown in Figure 11, the ratio of the non-magnetic modified portion is 40 (volume %) or less by setting the carbon [C] concentration (weight %) to 0.1 wt% or more and the manganese [Mn] concentration (weight %) to 10 wt% or more. Also, by setting the carbon [C] concentration (weight %) to 0.2 wt% or more and the manganese [Mn] concentration (weight %) to 15 wt% or more, the ratio of the non-magnetic modified portion is 10 (volume %) or less.

[0064] Furthermore, as shown in Figure 11, it was confirmed that by increasing the carbon [C] concentration (weight%) of the non-magnetic modified portion from 0.01% by weight to 0.2% by weight or more, the manganese [Mn] concentration (weight%) can be reduced from 25% (weight%) to about 15% (weight%) while maintaining approximately the ratio (volume%) of the ferromagnetic phase in the non-magnetic modified portion. [Explanation of Symbols]

[0065] 5. Paste containing a non-magnetic modification source (paste) 13 Rotor core 14. Bridge section (area requiring demagnetic modification) 16. Insulating coating 18 Electrical steel sheet 22 Electrical steel sheet 40 Demagnetization device 42 Laser light irradiation means 42a Laser light irradiation means 42b Laser light irradiation means 42c Laser light irradiation means 43 Control Unit Group I Group II Group III Block B (specific area) P coating pattern

Claims

1. A paste containing a non-magnetic modification source that requires melting in a subsequent process to be used in areas of electrical steel sheets where non-magnetic modification is necessary, Manganese powder, which is a non-magnetic modification source, A resin ink containing components that can be carbonized by heating, A paste containing a non-magnetic modifying source, characterized by including the following.

2. A demagnetizing apparatus for demagnetizing multiple specific areas formed by applying the demagnetizing modification source-containing paste described in claim 1 to multiple locations on an electrical steel sheet that requires demagnetizing modification, by heating and melting each of these areas, A laser beam irradiation means that changes the laser beam irradiation position to correspond to multiple specific areas and heats and melts multiple specific areas, A control unit that controls the laser beam irradiation position by the laser beam irradiation means, Equipped with, The control unit is characterized by dividing multiple locations on the electromagnetic steel sheet that require demagnetization modification into multiple groups, and controlling the laser irradiation position so that the timing of heating and melting does not overlap between the groups.

3. A rotor core in which electromagnetic steel sheets made of Fe-Si alloy are laminated with an insulating coating in between, The rotor core is characterized in that the electromagnetic steel sheet has a bridge portion containing an Fe-Si-Mn-C alloy, which has been demagnetized and modified with the demagnetizing modification source-containing paste described in claim 1.

4. The rotor core according to claim 3, characterized in that the concentration of carbon [C] in the bridge portion is 0.1% by weight or more, and the concentration of manganese [Mn] is 10% by weight or more.

5. A method for manufacturing a rotor core using a paste containing a non-magnetic modification source as described in claim 1, A process of applying a paste containing a non-magnetic modification source to multiple locations on an electrical steel sheet that requires non-magnetic modification, A process for demagnetizing and modifying an electrical steel sheet, in which multiple locations of an electrical steel sheet coated with a paste containing a demagnetizing modification source are divided into multiple groups, and multiple locations are heated and melted in such a way that the timing of heating and melting does not overlap between the groups, and then solidified; A method for manufacturing a rotor core, characterized by having the following features.

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