Paste containing a non-magnetic modification source, a coating apparatus therefor, a rotor core using the same, and a method for manufacturing the same.

Abstract

The present invention provides a rotor core that can perform demagnetic modification of the bridge portion more easily and quickly than conventional methods, and can sufficiently and stably reduce the magnetic permeability 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 alloy that have been demagnetically modified with a paste containing a demagnetic modification source which includes manganese powder as a demagnetic modification source, an organic binder, a thixotropic agent and an organic solvent.

Description

Technical Field

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

Background Art

[0002] In recent years, initiatives toward realizing a low-carbon or decarbonized society have intensified, and research and development on electric vehicles that travel using rotational power from rotating electrical machines have been conducted to reduce CO₂ emissions and improve energy efficiency in vehicles as well. Conventionally, as a rotor core for a rotating electrical machine, one in which a bridge portion (also referred to as a reinforcing rib) formed around a permanent magnet accommodation hole is subjected to a demagnetization treatment is known (see, for example, Patent Document 1). Specifically, in this rotor core, the magnetic permeability of the bridge portion is made lower than the magnetic permeability of the general portion of the electromagnetic steel sheet by alloying the modifying metal powder applied to the bridge portion with the metal contained in the electromagnetic steel sheet forming the rotor core. As a result, the rotating electrical machine can suppress an apparent decrease in permeance between the rotor and the stator, and can prevent a reduction in efficiency.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the rotor core is formed by laminating a plurality of electromagnetic steel sheets, and the bridge portions number as many as several tens per single electromagnetic steel sheet. Therefore, the conventional rotor core has a problem that the demagnetization of the bridge portions is complicated, and it takes time to manufacture the rotor core. In addition, the conventional demagnetization method in which only metal powder is adhered to the bridge portions has a problem that the magnetic permeability of the bridge portions cannot be sufficiently and stably reduced.

[0005] Therefore, the object of the present invention is to provide a paste containing a demagnetic modification source that can demagneticize the bridge portion more easily and quickly than conventional methods, and can sufficiently and stably reduce the magnetic permeability of the bridge portion, a coating apparatus therefor, a rotor core using the same, and a method for manufacturing the same. 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, an organic binder, a thixotropic agent, and an organic solvent.

[0007] The second aspect of the present invention, which solves the above-mentioned problems, is a coating apparatus for the non-magnetic modification source-containing paste, comprising: a rotating body made of a cylindrical rotary plate having through holes for applying the non-magnetic modification source-containing paste to a position including the portion of the electrical steel sheet to be demagnetized; a rotational driving means for the rotating body; a paste supply means for supplying the non-magnetic modification source-containing paste into the rotating body; a squeegee for blocking the non-magnetic modification source-containing paste that moves in the rotational direction of the rotating body within the rotating body; and a synchronization means for synchronizing the rotational speed of the rotating body with the feed speed of the electrical steel sheet. It is characterized by having the following features.

[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 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 that solves the above problems is a method for manufacturing a rotor core using the demagnetizing modifying source-containing paste, comprising: a coating step of applying the demagnetizing modifying source-containing paste to a predetermined thickness to a position on the electromagnetic steel sheet including a portion to be demagnetized; and a demagnetizing modification step of melting the electromagnetic steel sheet and the demagnetizing modifying source to form an Fe-Si-Mn alloy in the portion to be demagnetized, wherein the thickness of the demagnetizing modifying source-containing paste applied in the coating step is set to a thickness containing 25% or more of the manganese powder by weight ratio with respect to the portion to be demagnetized. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a paste containing a non-magnetic modification source that can perform non-magnetic modification of the bridge portion more easily and quickly than in the conventional method, and that can sufficiently and stably reduce the magnetic permeability of the bridge portion, a coating apparatus therefor, a rotor core using the same, and a method for manufacturing the same. [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 diagram illustrating the configuration of a coating apparatus for a paste containing a non-magnetic modification source. [Figure 4] Figure 3 is an unfolded view of the rotating body that constitutes the coating apparatus shown. [Figure 5] This is a schematic diagram of the application pattern of a paste containing a non-magnetic modification source. [Figure 6A] Figure 3 is an explanatory diagram illustrating the operation of the rotating body that constitutes the coating apparatus shown. [Figure 6B] This is a diagram illustrating the operation of a rotating body in a comparative example. [Figure 7] This is a manufacturing process diagram of a rotor core according to an embodiment of the present invention. [Figure 8]This is an explanatory diagram of the application step of the non-magnetization modification source-containing paste. [Figure 9] This is a graph showing the relationship between the manganese concentration in the applied non-magnetization modification source-containing paste and the ferromagnetic phase ratio. [Figure 10] This is a graph showing the relationship between the thickness of the non-magnetization modification source-containing paste and the manganese weight ratio. [Mode for Carrying Out the Invention]

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

[0013] <Rotor Core> FIG. 1 is a configuration explanatory view of a rotating electrical machine 10 provided with the 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 it can also be used for various other applications. As shown in FIG. 1, the rotating electrical machine 10 is configured to include 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. Thereby, 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 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 are grouped as one set and 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 circumferential center, 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 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 rotating electrical 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 FIG. 1, reference numeral 23 denotes a stator core of the stator 21, reference numeral 24 denotes a yoke of the stator 21, and reference numeral 27 denotes a coil arranged in a slot 26 so as to wind around 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. 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 by alloying with the metal component (modifier) ​​contained in the non-magnetic modification source-containing paste, which will be described next. In Figure 2, reference numeral 16 denotes an insulating coating formed on both sides of the electrical steel sheet 18 at a nanometer to micrometer level. This insulating coating 16 is formed on the electromagnetic steel sheet 22 (see Figure 3), which will become the raw material for the electromagnetic steel sheet 18, before the paste containing the non-magnetic modification source, which will be described next, is applied.

[0021] <Paste containing non-magnetic modifier> The paste containing the non-magnetic modifier of this embodiment comprises manganese powder, which is the non-magnetic modifier, an organic binder, 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. In pastes containing a non-magnetic modification source, the manganese powder content is preferably 85.0 to 95.0% by weight.

[0022] Examples of organic binders 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, polyvinyl alcohol, and polyvinyl butyral. Among these, acrylic resins are preferred. The organic binder functions as a binder component that binds the manganese powder together into a paste containing a non-magnetic modification source, and also functions as a carbon source for the carbon atoms diffused into the electrical steel sheet in the non-magnetic modification process described later (see Figure 7). The preferred content of the organic binder in the paste containing the non-magnetic modification source is 0.3 to 1.0% by weight.

[0023] 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 the non-magnetic modification source 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. In pastes containing a non-magnetic modification source, the preferred content of the thixotropic agent is 0.5 to 1.5% by weight.

[0024] 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.

[0025] The organic solvent imparts fluidity to the paste containing the non-magnetic modification source and also functions as a carbon source for the carbon atoms diffused into the electrical steel sheet in the non-magnetic modification process described later (see Figure 7). The preferred content of the organic solvent in the paste containing the non-magnetic modification source is 2.5 to 15.0% by weight. A paste containing a non-magnetic modification source can be prepared by mixing the above-mentioned components.

[0026] <Applicator for applying paste containing a non-magnetic modification source> Figure 3 is an explanatory diagram of the configuration of the coating apparatus 30 for the paste containing a non-magnetic modification source. As shown in Figure 3, the coating apparatus 30 of this embodiment is configured to apply a paste 5 containing a non-magnetic modification source (hereinafter sometimes simply referred to as "paste 5") to the surface of an electromagnetic steel sheet 22 that is transported at a predetermined feed rate V1, using a predetermined coating pattern P (see Figure 5) described later.

[0027] In this embodiment, the electrical steel sheet 22 is the raw material for the electrical steel sheet 18 (see Figure 2), and is preferably made of the Fe-Si alloy described above.

[0028] As shown in Figure 3, the coating apparatus 30 of this embodiment comprises a rotating body 31 and a rotational driving means 32 for the rotating body 31. The coating apparatus 30 also comprises a paste supply means 33 for supplying paste 5 into the rotating body 31 and a squeegee 34 positioned inside the rotating body 31. The coating apparatus 30 also comprises a synchronization means 35 for synchronizing the rotational speed of the rotating body 31 with the feed speed of the electrical steel sheet 22.

[0029] As shown in Figure 3, the rotating body 31 is formed from a cylindrical rotary plate. The rotating body 31 is positioned above the electromagnetic steel sheet 22, with its outer circumferential surface in contact with the upper surface of the electromagnetic steel sheet 22. Figure 4 is an unfolded view of the rotating body 31. As shown in Figure 4, the planar shape of the unfolded body of revolution 31 is a parallelogram with opposite sides of length L equal to the circumference of the body of revolution 31. The body of revolution 31 is formed by roll-forming a plate of a predetermined thickness T1 (see Figure 3) having such a parallelogram planar shape, and joining the edges E shown in Figure 4. The thickness T1 of the rotating body 31 shown in Figure 3 can be set to be approximately equal to the thickness T2 of the paste 5 applied to the electromagnetic steel sheet 22. Incidentally, in this embodiment, the rotating body 31 is assumed to have a thickness T1 of 0.25 mm or more.

[0030] As shown in Figure 4, the rotating body 31 has a plurality of through holes H that penetrate the plate in the thickness direction (the direction perpendicular to the plane of the paper in Figure 4). Multiple through holes H are arranged to line up on a circumference of a predetermined diameter, forming a coating pattern P of paste 5 (see Figure 3) on the electromagnetic steel sheet 22 (see Figure 3). Figure 5 is a schematic diagram of the application pattern P of paste 5 (see Figure 3). As shown in Figure 5, the coating pattern P is formed in a plan view as a collection of minute rectangular partitioned regions Pa.

[0031] This partitioned area Pa (see Figure 5) is formed to correspond to the bridge portion 14 (see Figure 2) of the electrical steel sheet 18 (see Figure 2). Specifically, as shown in Figure 5, the partitioned area Pa is formed with an area that encompasses the bridge section 14, which is indicated by the dashed line. In other words, the partitioned region Pa is formed in a position that includes the bridge portion 14 (see Figure 2), which is the "non-magnetic portion" of the electromagnetic steel sheet 22 (see Figure 3) through which the electromagnetic steel sheet 18 (see Figure 2) is punched, as described above.

[0032] Returning to Figure 4, the rotating body 31 has multiple coating patterns P formed in the through holes H, as described above. In this embodiment, the coating pattern P of the rotating body 31 is arranged in two rows in the direction where opposite sides of length L face each other (the axial direction of the rotating body 31) when the rotating body 31 is unfolded as shown in Figure 4, and is continuous in a direction parallel to the opposite sides (the circumferential direction of the rotating body 31) to form a 60-degree staggered pattern. Furthermore, in this embodiment, as shown in Figure 4, the edge E of the rotating body 31, which forms the joint of the rotating body 31, is set to a position that avoids the coating pattern P.

[0033] As shown in Figure 3, the rotational drive means 32 is provided at one end of the rotation axis Ax of the rotating body 31 in the direction of extension (the direction perpendicular to the plane of the paper in Figure 3). In this embodiment, the rotational drive means 32 is assumed to consist of an electric motor and a reduction gear that rotate the rotating body 31 at a predetermined speed. As shown in Figure 3, the paste supply means 33 is configured to continuously or intermittently supply the paste 5 into the rotating body 31. In this embodiment, the paste supply means 33 is assumed to have a paste storage section (not shown), a pipe 33a extending from the storage section into the interior of the rotating body 31, and a pump (not shown) provided along the extension of the pipe 33a.

[0034] As shown in Figure 3, the squeegee 34 is composed of a plate that blocks the paste 5 which moves in the direction of rotation of the rotating body 31 inside the lower part of the rotating body 31. In this embodiment, the squeegee 34 extends in the axial direction of the rotating body 31 (perpendicular to the plane of the paper in Figure 3) on the central side of the rotating body 31, and one end of the squeegee 34 is supported by a support (not shown). The other end of the squeegee 34, located below the first end, slides against the inner circumferential surface of the rotating body 31. Furthermore, the squeegee 34 in this embodiment is assumed to be made of a flexible material such as a hard rubber sheet, a resin sheet, or a metal sheet. The other edge of the squeegee 34 that slides against the inner circumferential surface of the rotating body 31 is slightly displaced in the direction of rotation of the rotating body 31.

[0035] The synchronization means 35 is configured to synchronize the rotational speed of the rotating body 31 (circumferential speed V2 on the outer surface of the rotating body 31) with the feed rate V1 of the electromagnetic steel sheet 22. In this embodiment, the synchronization means 35 has a roller 35a. The roller 35a is positioned below the rotating body 31 and is in pressure contact with the lower surface of the electromagnetic steel sheet 22 that is in contact with the outer circumferential surface of the rotating body 31.

[0036] Furthermore, although not shown in the figures, the synchronization means 35 has a gear mechanism that transmits the rotational motion of the rotating body 31 to the roller 35a. This gear mechanism transmits a rotational force to the roller 35a in the opposite direction to that of the rotating body 31, and sets the speed V3 of the outer surface of the roller 35a to be equal to the speed V2 of the outer surface of the rotating body 31. As a result, the electrical steel sheet 22 is transported at a feed rate V1 equal to the speed V2 of the outer surface of the rotating body 31. In this embodiment, the feed rate V1 is assumed to be approximately 20 m / min. However, the feed rate V1 can be adjusted as appropriate.

[0037] Next, the operation of the rotating body 31 will be described. Figure 6A is an explanatory diagram of the operation of the rotating body 31. As shown in Figure 6A, when the rotating body 31 rotates in the direction of feeding the electromagnetic steel sheet 22, the paste 5 inside the lower part of the rotating body 31 tends to follow the direction of rotation of the rotating body 31. The squeegee 34 blocks the paste 5 which is driven in the direction of rotation of the rotating body 31. When the through-hole H of the rotating body 31 reaches the upstream side of the squeegee 34 in the direction of rotation of the rotating body 31, the paste 5 pushed by the squeegee 34 fills the through-hole H.

[0038] As the rotating body 31 rotates further, the squeegee 34 pushes the paste 5 filled in the through hole H toward the electrical steel sheet 22, forming tiny rectangular parallelepiped-shaped blocks B made of the paste 5 that adhere to the upper surface of the electrical steel sheet 22. These blocks B have a planar shape corresponding to the rectangular partitioned area Pa (see Figure 5) of the coating pattern P (see Figure 5), and have a thickness T2 that is approximately equal to the thickness T1 (see Figure 3) of the plate body forming the rotating body 31 (see Figure 3).

[0039] In this embodiment, the coating thickness T2 of the paste 5, which is the thickness of block B, is a thickness that contains 25% or more, preferably 30% or more, of the manganese powder by weight relative to the bridge portion 14 (see Figure 2). Specifically, the application thickness T2 of paste 5 (see Figure 6A) is preferably 0.25 mm or more, as will be explained in the examples described later.

[0040] Figure 6B is an explanatory diagram of the operation of the comparative example rotating body 31a. As shown in Figure 6B, unlike the rotating body 31 in this embodiment (see Figure 6A), the rotating body 31a does not have a through hole H (see Figure 6A), and the portion corresponding to the through hole H is a mesh M. In this comparative example, the rotating body 31a has a thickness T3 of block B that adheres to the upper surface of the electromagnetic steel sheet 22, which is less than half of the thickness T2 (see Figure 6A). In Figure 6B, reference numeral 5 denotes paste and reference numeral 34 denotes a squeegee.

[0041] <Manufacturing method for rotor cores> Next, we will explain the manufacturing method of the rotor core 13 (see Figure 1). As shown in Figure 7, this manufacturing method includes a step of applying paste 5 (see Figure 3) to an electrical steel sheet 22 (see Figure 3) (step S101), a step of demagnetizing and modifying the electrical steel sheet 22 (see Figure 3) to which paste 5 (see Figure 3) has been applied (step S102), and a step of punching and in-die lamination of the electrical steel sheet 22 (see Figure 3) (step S103).

[0042] Figure 8 is an explanatory diagram of the coating process (step S101). As shown in Figure 8, in the coating process (step S101 in Figure 7), the electromagnetic steel sheet 22 is conveyed by the synchronization means 35 (see Figure 3) at a feed rate V1 equal to the speed V2 of the outer surface of the rotating body 31. In this process, as shown in Figure 6A, the squeegee 34 blocks the paste 5 driven by the rotating body 31, and a block B of paste 5 with a thickness T2 and a planar shape through the through hole H is attached to the upper surface of the electromagnetic steel sheet 22. As shown in Figure 8, multiple coating patterns P are continuously formed on the upper surface of the electromagnetic steel sheet 22 as it is transported at a feed rate V1 using paste 5.

[0043] In the demagnetization modification process (step S102) shown in Figure 7, energy beams such as laser light and electron beams are sequentially irradiated onto each block B (see Figure 8) that forms the coating pattern P. This heats the electrical steel sheet 22 (see Figure 8) and block B (see Figure 8) to a high temperature. The manganese powder constituting block B melts, and the components of paste 5 other than the manganese powder burn, with some of them carbonizing. As a result, the metal components forming the electrical steel sheet 22 and the manganese form an Fe-Si-Mn alloy, causing the magnetic permeability to decrease in the areas irradiated by the energy beam. The entire section region Pa (see Figure 5), including the bridge portion 14, of the electrical steel sheet 22 is demagnetized. At this time, some of the carbon atoms generated in the burnt block B diffuse into the electrical steel sheet 22 to form an Fe-Si-Mn-C alloy.

[0044] Next, in this manufacturing method, the electromagnetic steel sheet 22 is punched out in 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, the portion of the non-magnetic modified partition region Pa (see Figure 5) other than the bridge portion 14 (see Figure 5) is trimmed off. Then, the electromagnetic steel sheets 18 punched out from the electromagnetic steel sheet 22 (see Figure 8) are stacked and crimped within a predetermined mold, and if necessary, the stacked electromagnetic steel sheets 18 are integrated with adhesive or the like, completing the punching and in-die stacking process (step S103). This completes the rotor core 13 (see Figure 1) of this embodiment.

[0045] <Effects> Next, the effects and benefits of the non-magnetic modification source-containing paste, the coating apparatus thereof, the rotor core using the same, and the manufacturing method thereof according to this embodiment will be described. The paste 5 (paste containing a non-magnetic modification source) 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 electrical steel sheet 22 where non-magnetic modification is required, and is characterized by containing manganese powder as the non-magnetic modification source, an organic binder, a thixotropic agent, and an organic solvent.

[0046] 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) allows for the non-magnetic modification source to remain in contact with the electrical steel sheet 22 for a long period of time. Furthermore, this paste 5 (paste containing a non-magnetic modification source) allows for the precise maintenance of 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 non-magnetic modification 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.

[0047] Furthermore, the coating apparatus 30 according to this embodiment is a coating apparatus 30 for paste 5 (paste containing a non-magnetic modification source), and is characterized by comprising: a rotating body 31 made of a cylindrical rotary plate having through holes H for applying paste 5 to a position including the non-magnetic portion (bridge portion 14) of the electrical steel sheet 22; a rotational driving means 32 for the rotating body 31; a paste supply means 33 for supplying paste 5 into the rotating body 31; a squeegee 34 for blocking the paste 5 that follows the rotational direction of the rotating body 31 inside the rotating body 31; and a synchronization means 35 for synchronizing the speed V2 of the rotating body 31 and the feed speed V1 of the electrical steel sheet 22.

[0048] With this coating apparatus 30, a demagnetizing modification source can be continuously applied to the electrical steel sheet 22. Furthermore, with this coating apparatus 30, a paste 5 of the thickness necessary for demagnetizing the electrical steel sheet 22 can be accurately applied to the appropriate location. As a result, the coating apparatus 30 of this embodiment can demagnetize the bridge portion 14 more easily and quickly than conventional methods, and can sufficiently and stably reduce the magnetic permeability of the bridge portion 14.

[0049] 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 alloy that have been demagnetically modified with paste 5. In this type of rotor core 13, the bridge portion 14 is demagnetically modified with paste 5 (paste containing a demagnetic modification source), so the permeability of the bridge portion 14 can be reduced sufficiently and stably.

[0050] 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 comprises a coating step of applying paste 5 to a predetermined thickness T2 at a position including the bridge portion 14 (the portion to be demagnetized) of the electromagnetic steel sheet 22, and a demagnetization modification step of melting the electromagnetic steel sheet 22 and the demagnetization modification source to form an Fe-Si-Mn alloy in the bridge portion 14, wherein the thickness T2 of the paste 5 applied in the coating step is set to a thickness containing manganese at a weight ratio of 25% or more relative to the bridge portion 14. This method for manufacturing the rotor core 13 allows for easier and faster demagnetization of the bridge portion 14 than conventional methods. Furthermore, this manufacturing method allows for more reliable and precise application of the demagnetization source to the areas of the electrical steel sheet 22 where demagnetization is required.

[0051] 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]

[0052] Next, an example of the method for manufacturing the rotor core 13 according to the present invention will be described. In this embodiment, the preferred range for the application thickness T2 (see Figure 3) of the paste 5 to the non-magnetic 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 an organic binder, 1% by weight of an organic thixotropic agent, and 4% by weight of an organic solvent.

[0053] Next, test specimens were prepared by applying paste 5 to the surface of a 0.3 mm thick Fe-Si alloy electrical steel sheet. Forty different test specimens were prepared, each with a paste 5 application thickness T2 varying within the range of 0.16 mm to 0.36 mm.

[0054] Next, laser light was irradiated onto the paste 5 applied to these 40 types of test pieces to partially demagnetize the test pieces made of electromagnetic steel sheets. The proportion of the ferromagnetic phase (volume %) and the carbon concentration (weight %) were measured in the demagnetized portion. Then, the relationship between the manganese concentration (weight %) and the proportion of the ferromagnetic phase (volume %) in the portion coated with paste 5 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 carbon [C] concentration (weight %) was measured by infrared absorption spectroscopy of carbon contained in the combustion gas in the oxygen stream of the non-magnetic modification section. The manganese [Mn] concentration (weight %) was measured by ICP emission spectroscopy. The results are shown in Figure 9.

[0055] Figure 9 is a graph showing the relationship between the manganese concentration (weight %) and the ferromagnetic phase ratio (weight %) in the applied paste 5. As shown in Figure 9, it was confirmed that the test specimen (electrical steel sheet) became non-magnetic when the manganese concentration was 25% by weight, regardless of whether the carbon concentration was 0% by weight, 0.01% by weight, 0.1% by weight, or 0.2% by weight.

[0056] Figure 10 is a graph showing the relationship between the thickness (mm) of the applied paste 5 and the manganese concentration (weight %) in the applied paste 5. As shown in Figure 10, it was found that when the carbon concentration is at least 0.01% by weight, the manganese concentration in the applied paste 5 becomes 25% by weight or more when the thickness of paste 5 is 0.25 mm or more. It was verified that a coating thickness T2 of paste 5, which demagnetizes electrical steel sheets, of 0.25 mm or more is preferable. [Explanation of symbols]

[0057] 5. Paste containing a non-magnetic modification source. 13 Rotor core 14. Bridge section (part that becomes non-magnetic) 16. Insulating coating 18 Electrical steel sheet 22 Electrical steel sheet 30 Coating device 31. Solids of revolution 32 Rotary drive means 33 Paste supply means 34 squeegee 35 Synchronization means H through hole

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, Organic binder and Thixotropic agents and Organic solvents and A paste containing a non-magnetic modifying source, characterized by including the following.

2. A coating apparatus for a paste containing a non-magnetic modification source according to claim 1, A rotating body consisting of a cylindrical rotary plate having through holes for applying the demagnetizing modification source-containing paste to a position including the portion of the electromagnetic steel sheet to be demagnetized, The rotational driving means for the rotating body, A paste supply means for supplying the paste containing the non-magnetic modification source into the interior of the rotating body, A squeegee that blocks the paste containing the non-magnetic modification source that moves in the direction of rotation of the rotating body inside the rotating body, A synchronization means for synchronizing the rotational speed of the rotating body with the feed rate of the electromagnetic steel sheet, A coating apparatus characterized by comprising:

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 alloy, which has been demagnetized and modified with the demagnetizing modification source-containing paste described in claim 1.

4. A method for manufacturing a rotor core using a paste containing a non-magnetic modification source as described in claim 1, A coating step of applying the paste containing the demagnetizing modifier to a predetermined thickness at a location on the electrical steel sheet that includes a portion to be demagnetized, A demagnetizing modification step involves melting the electrical steel sheet and the demagnetizing modification source to form an Fe-Si-Mn alloy in the area to be demagnetized, It has, A method for manufacturing a rotor core, characterized in that the thickness of the paste containing the non-magnetic modification source applied in the coating step is set to a thickness that contains 25% or more of the manganese powder by weight relative to the portion to be demagnetized.

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