Method for manufacturing an iron core

Abstract

To provide an iron-core and a manufacturing method of the same which can protect addition of core loss, adherence of sputter and reduction of space factor.SOLUTION: A manufacturing method of an iron-core includes a process where a recess 5a recessed to the inside laminates thin plate-like core pieces formed on the periphery and forms a laminate 3, a process where an ultraviolet hardening resin 6 is implanted in a groove 5 formed extending in the lamination direction on the outer peripheral surface of the laminate 3 within a range where the ultraviolet hardening resin 6 does not project from the groove 5, and a process where ultraviolet ray is radiated to the implanted ultraviolet hardening resin 6 to harden the ultraviolet hardening resin 6.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the present invention relate to a method for manufacturing a core formed by laminating thin plate-shaped core pieces and to the core.

Background Art

[0002] Conventionally, a core formed by laminating thin plate-shaped core pieces has been known. Such a core is manufactured, for example, by fixing the laminated core pieces by welding as in Patent Document 1, caulking, or laminating those with an adhesive applied to the surface of the core pieces.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in a core manufactured by welding or caulking, there is a problem that iron loss increases compared to a state where only core pieces are laminated because stress generated during welding or caulking remains in the core. Further, during welding, so-called spatter may occur, and if the spatter adheres to the surface of the core, it needs to be removed. Further, when an adhesive is applied between the core pieces, there is a problem that the occupancy rate decreases, and this problem becomes more prominent as the core material is made thinner for higher performance.

[0005] Therefore, a method for manufacturing a core capable of preventing an increase in iron loss, adhesion of spatter, and a decrease in occupancy rate is provided. Method provided.

Means for Solving the Problems

[0006] The method for manufacturing the core according to the embodiment includes a step of forming a laminate by laminating thin plate-shaped core pieces 2 having recesses recessed inwardly formed on the outer peripheral portion, a step of injecting an ultraviolet curable resin into a groove portion formed to extend in the lamination direction on the outer peripheral surface of the laminate within a range not protruding from the groove portion, and a step of irradiating the injected ultraviolet curable resin with ultraviolet rays to cure the ultraviolet curable resin.

Brief Description of the Drawings

[0007]

Figure 1

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Embodiments for Carrying Out the Invention

[0008] Hereinafter, the embodiments will be described with reference to the drawings. As shown in FIG. 1, a stator core 1 which is the core assumed in the present embodiment is formed by laminating thin plate-shaped core pieces 2. The core pieces 2 are formed by punching an electromagnetic steel sheet into an annular shape by a press or the like as is well known. In the present embodiment, as the electromagnetic steel sheet forming the core pieces 2, a steel sheet having a relatively high silicon content and a relatively thin plate thickness for improving high-frequency characteristics is assumed. Further, as is well known, the surface of the electromagnetic steel sheet is covered with an insulating film.

[0009] Then, three blocks 2A to 2C, each formed by laminating a predetermined number of core pieces 2, are laminated by so-called rotational lamination in which they are shifted in the circumferential direction relative to each other, thereby forming a laminate 3 in which a plurality of core pieces 2 are laminated in the thickness direction.

[0010] On the outer peripheral surface of this laminate 3, a plurality of ear portions 4 that extend radially outward are provided. In the present embodiment, the ear portions 4 are provided at three locations on the outer peripheral surface of the stator core 1 at substantially 120° intervals. A through hole 4a that penetrates in the lamination direction is formed in the ear portion 4, and the through hole 4a is used to attach the stator core 1 to a housing (not shown) or the like.

[0011] Further, on the outer peripheral surface of the laminate 3, a plurality of groove portions 5 that extend in the lamination direction of the core pieces 2 are formed. Although details will be described later, an ultraviolet curable resin 6 for fixing each core piece 2 is provided in the groove portion 5. The groove portions 5 are located at positions shifted from the ear portions 4 in the circumferential direction of the laminate 3 and are formed at six locations on the outer peripheral surface at substantially 60° intervals. However, the number of blocks 2, the number of ear portions 4, or the number of groove portions 5 is an example and is not limited thereto.

[0012] Further, the groove portions 5 are formed by laminating the core pieces 2. Specifically, as shown in FIG. 2, the core piece 2 has an ear portion 4 and a through hole 4a formed on its outer peripheral portion and a recessed portion 5a recessed on the inner peripheral side, and a plurality of slits 7a that serve as a housing portion 7 for accommodating a winding and a hole portion 8a that is connected to the slit 7a and serves as a hollow portion 8 for accommodating a rotor are formed. Then, by laminating the core pieces 2 in the plate thickness direction, as shown in FIG. 1, the recessed portions 5a are arranged in the lamination direction to form the groove portions 5, and the housing portion 7 and the hollow portion 8 are formed.

[0013] As shown in a plan view from the lamination direction in FIG. 3, this recess 5a is formed in a shape in which two curved portions inclined from the outer periphery toward the inner periphery of the core piece 2 and a flat portion at their center are smoothly connected. At this time, the recess 5a has a depth of approximately 1.3 mm from a virtual line (CL) indicating the outer periphery of the laminate 3 at its central portion, and its width in the circumferential direction is formed to be approximately 10 mm. However, the shape, depth, and width of the recess 5a shown here are merely examples.

[0014] The ultraviolet curable resin 6 is a resin material that cures when irradiated with ultraviolet rays and has a certain degree of viscosity in a state of being injected or filled into the groove portion 5. As this ultraviolet curable resin 6, for example, those having a heat resistance of about 100°C and being cured by irradiation with ultraviolet rays for about several seconds can be adopted.

[0015] Then, the ultraviolet curable resin 6 is injected into the groove portion 5 in an amount that fits within the range on the inner peripheral side of the virtual line (CL). That is, the ultraviolet curable resin 6 is not simply applied to the surface of the groove portion 5, but is provided in a state having a certain thickness without protruding from the groove portion 5, in other words, without spreading to the outer peripheral surface of the laminate 3. Note that the ultraviolet curable resin 6 may be any resin as long as it can ensure the required heat resistance and durability. For example, those used as so-called adhesives having adhesiveness can also be used.

[0016] Next, the operation of the above-described configuration will be described. As described above, when a core such as the stator core 1 is fixed by welding or caulking, compared with the laminate 3 in a state where the core pieces 2 are laminated, iron loss may increase due to the residual stress generated during welding or caulking. Also, so-called spatter may occur during welding, and if the spatter adheres to the surface of the core, it is necessary to remove it.

[0017] In addition, when an adhesive is applied and fixed between the core pieces 2, there is a problem that the occupation ratio decreases, and this problem becomes more prominent as the core material is made thinner for high performance improvement such as improving high-frequency characteristics. Note that the occupation ratio may be considered as the volume of the core piece 2 with respect to the volume of the stator core 1 formed at a predetermined height (L0). Therefore, in the present embodiment, the following manufacturing method simultaneously suppresses an increase in iron loss, adhesion of sputter, and a decrease in the occupation ratio.

[0018] Specifically, as shown in FIG. 4, in the manufacturing process of the stator core 1, a punching process for punching the core piece 2 is performed (S1). In this punching process, for example, an electromagnetic steel sheet is punched by a press machine to form a generally annular and thin plate-shaped core piece 2. At this time, as shown in FIG. 3, the core piece 2 is formed with an ear portion 4, a concave portion 5a that becomes a groove portion 5 in a stacked state, a slit 7a that forms a housing portion 7 in a stacked state, and a hollow portion 8 for housing a rotor on its outer peripheral side.

[0019] Subsequently, a stacking process for stacking the core pieces 2 in units of a predetermined number of blocks is performed (S2), and a rotational stacking process for rotationally stacking the blocks is performed (S3). At this time, although not shown, the press machine has a structure in which the punched core pieces 2 fall downward as they are and the core pieces 2 are stacked in the order in which they are punched. Therefore, in step S2, when a predetermined number is punched, that is, when a predetermined number of core pieces 2 are stacked, they are taken out as one block.

[0020] Then, the taken-out block is rotationally stacked in step S3 by rotating the next taken-out block 2B by 120° in the circumferential direction with respect to the first taken-out block 2A and stacking the next taken-out block 2C by rotating it by 120° in the circumferential direction with respect to the block 2B, thereby forming a laminate 3.

[0021] Thus, even if there are variations in the plate thickness in the longitudinal or transverse direction of the electromagnetic steel sheet, the variations are absorbed by stacking them in a rotational manner. That is, the height of the laminate 3 becomes substantially uniform in its circumferential direction. Although not shown in the figure, when stacking in a rotational manner, in order for the blocks 2A to 2C to be concentric and to enable the pressing described later, jigs for centering the core pieces 2 are provided on a press, and the respective blocks 2A to 2C are stacked on the press.

[0022] Subsequently, a burr crushing and pressing process is performed (S4). Since the core pieces 2 are punched by a press as described above, burrs may be generated at the cutting portions. Therefore, in step S4, a relatively strong pressure is applied to the laminate 3 in the stacking direction to physically crush the possible burrs generated in the core pieces 2.

[0023] Thereafter, a pressurizing process during injection is performed (S5), in which a pressure relatively smaller than that during burr crushing and pressing is applied to the laminate 3 in the stacking direction. In this process, as shown in FIG. 5, a pressure is applied such that the height (L1) of the laminate 3 becomes larger than a predetermined height (L0) required for the stator core 1. In other words, in the pressurizing process during injection, a pressure relatively smaller than that when the laminate 3 is made to have the predetermined height (L0) is applied.

[0024] Then, while maintaining the pressure, an injection process is performed in which the ultraviolet curable resin 6 is injected into the groove portion 5 (S6). In this injection process, for example, the ultraviolet curable resin 6 is injected while moving a dispenser 10 along the groove portion 5. At this time, the ultraviolet curable resin 6 is injected into each groove portion 5 respectively.

[0025] Also, in the injection process, since a relatively small pressure is applied as described above, it is assumed that a slight gap is generated in a very shallow range (ΔW) from the surface of the groove portion 5 to the inner peripheral side between the respective core pieces 2. Therefore, when the ultraviolet curable resin 6 is injected, it is assumed that the ultraviolet curable resin 6 penetrates into the gap.

[0026] When the injection of the ultraviolet curable resin 6 is completed, a pressurizing step during curing is performed to apply a relatively large pressure (S7). In this pressurizing step during curing, as shown in FIG. 6, a pressure is applied to make the laminate 3 have a predetermined height (L0). Then, in that state, the irradiation device 11 that irradiates ultraviolet rays is moved along the groove portion 5 into which the ultraviolet curable resin 6 has been injected, thereby curing the ultraviolet curable resin 6 (S8).

[0027] At this time, when the ultraviolet curable resin 6 has penetrated into the gaps, since there are slightly gaps between the core pieces 2 and ultraviolet rays can enter these gaps, it is considered that the ultraviolet curable resin 6 that has penetrated between the core pieces 2 can be cured.

[0028] And, if there are uncured portions among the plurality of groove portions 5 (S9: NO), the process proceeds to step S8 to cure the ultraviolet curable resin 6. On the other hand, when all portions are cured (S9: YES), the pressure is released (S10), the core is taken out from the press (S11), and then it is conveyed to the next process.

[0029] In this next process, operations such as inspection of the stator core 1, insertion of windings, and assembly to the frame are performed. And the inventors conducted tests using several types of ultraviolet curable resins 6 and confirmed that the stator core 1 can be fixed by the ultraviolet curable resin 6 in the process until it is assembled to the frame.

[0030] And since the stator core 1 is finally attached to the frame using the ear portions 4, it is considered that there is no problem as long as its shape can be maintained until it is attached to the frame. In other words, it was confirmed that the method of fixing the stator core 1 with the ultraviolet curable resin 6 sufficiently functions as a temporary fixing method and a temporary fixing member until the stator core 1 is attached to the frame in the manufacturing process of the stator core 1.

[0031] According to the embodiment described above, the following effects can be obtained. The method for manufacturing the iron core includes a step of forming a laminate 3 by laminating thin plate-shaped iron core pieces 2 having a recessed portion 5a recessed on the inner side formed on the outer peripheral portion, a step of injecting an ultraviolet curable resin 6 into a groove portion 5 formed to extend in the lamination direction on the outer peripheral surface of the laminate 3 within a range not protruding from the groove portion 5, and a step of irradiating the injected ultraviolet curable resin 6 with ultraviolet rays to cure the ultraviolet curable resin 6.

[0032] By curing the ultraviolet curable resin 6 in this way to fix each iron core piece 2, the iron core piece 2 is not exposed to a high temperature like during welding during manufacturing, and since it does not undergo thermal deformation, it is possible to suppress the deviation of the right angle of the iron core due to the undulating deformation of the end face, and it is also possible to prevent the iron loss from deteriorating due to the residual stress caused by the heat input.

[0033] Also, since sputtering does not adhere to the surface of the iron core, the operation of removing sputtering becomes unnecessary, and the production efficiency can be improved. Furthermore, by using the ultraviolet curable resin 6 that cures in about several seconds, it is possible to suppress an excessive increase in the time required for the operation.

[0034] Also, since each iron core piece 2 is fixed by the groove portion 5, it is possible to suppress a decrease in the occupation ratio compared to a configuration in which an adhesive is applied to the surface of the iron core piece 2 and laminated. Also, even when the iron core material is thinned for high performance, it is possible to suppress a large decrease in the occupation ratio.

[0035] In this way, in the method for manufacturing the iron core, a plurality of effects can be obtained simultaneously, thereby preventing an increase in iron loss, adhesion of sputtering, and a decrease in the occupation ratio.

[0036] Also, in the method for manufacturing the iron core, while applying pressure in the lamination direction to the laminate 3, the ultraviolet curable resin 6 is injected into the groove portion 5 and the injected ultraviolet curable resin 6 is irradiated with ultraviolet rays. Thereby, the manufactured stator iron core 1 can be set to a desired height.

[0037] Further, in the method of manufacturing the iron core, the pressure applied when injecting the ultraviolet curable resin 6 is made smaller than the pressure applied when irradiating the ultraviolet curable resin 6 with ultraviolet rays. Thereby, it is assumed that a gap is formed between the iron core pieces 2 in a range slightly from the surface of the groove portion 5, and the ultraviolet curable resin 6 penetrates into the gap, and it can be expected that the iron core pieces 2 are more firmly fixed by curing the penetrated ultraviolet curable resin 6.

[0038] In addition, since the fixing by the ultraviolet curable resin 6 does not depend on the properties and materials of the iron core pieces 2, for example, it can also be applied to the iron core pieces 2 made of thin plates of 0.2 mm or less. Thereby, the structure can be simplified.

[0039] Further, the iron core of the embodiment includes a laminate 3 formed by laminating a plurality of thin plate-shaped iron core pieces 2 having a recess 5a recessed inwardly formed on the outer peripheral portion, and is injected into a groove portion 5 formed to extend in the lamination direction on the outer peripheral surface of the laminate 3, and an ultraviolet curable resin 6 that fixes the plurality of iron core pieces 2 forming the laminate 3 to each other. With the iron core having such a configuration, it is possible to obtain the same effects as those of the above-described manufacturing method, such as suppressing an increase in iron loss, adhesion of spatter, and a decrease in occupation ratio.

[0040] The present invention is not limited only to the above-described embodiments, and the configurations and structures shown in the respective embodiments can be arbitrarily modified or combined without departing from the gist thereof.

[0041] In the embodiment, the groove portion 5 having a flat center in plan view is exemplified. However, for example, as shown in FIG. 7 as another shape example 1, a configuration can be adopted in which the groove portion 5 does not have a flat portion and is entirely curved. In this case, since the ultraviolet curable resin 6 accumulates along the surface of the groove portion 5, a wide range in the circumferential direction of the groove portion 5 is fixed by the ultraviolet curable resin 6, and each iron core piece 2 can be fixed more firmly.

[0042] Also, as shown as another shape example No. 2, the groove portion 5 can be formed by a combination of straight lines instead of a curved surface. In this case, the width in the circumferential direction on the outer side in the radial direction of the groove portion 5 can be made narrower than the width in the circumferential direction on the inner side in the inner circumferential diameter direction. More simply put, the opening of the groove portion 5 can be made narrower than the internal space.

[0043] In this case, since the ultraviolet curable resin 6 is a viscous body before curing, it can be injected into the groove portion 5, and since ultraviolet rays can be irradiated from the opening, the core piece 2 can be fixed. And since the opening is narrower than the inside of the groove portion 5, it is possible to prevent the ultraviolet curable resin 6 from peeling off to the outside.

[0044] Also, the groove portion 5 having such a shape may be used when fixing the laminate 3 by caulking. Therefore, while diverting the shape and manufacturing apparatus of the conventional core fixed by caulking, it is possible to adopt a fixing method using the ultraviolet curable resin 6.

[0045] Also, as shown as another shape example No. 3, the center of the groove portion 5 bulges, and a groove portion 5 in a ω shape can be formed in a plan view. The groove portion 5 having such a shape may be used when fixing the laminate 3 by welding. Therefore, while diverting the shape and manufacturing apparatus of the conventional core fixed by welding, it is possible to adopt a fixing method using the ultraviolet curable resin 6.

[0046] Also, in the embodiment, a configuration in which core pieces 2 having the same shape are laminated is exemplified, but a configuration in which core pieces 2 having different shapes of the concave portions 5a are laminated to form a laminate 3 can be adopted. For example, as shown as another lamination example No. 1 in FIG. 8, core pieces 2 having different shapes of the concave portions 5a can be laminated to form a shape having a step in the radial direction on the surface of the groove portion 5.

[0047] Then, by injecting and curing the ultraviolet curable resin 6 in a state of covering these steps, the steps can generate a so-called anchor effect to fix each core piece 2 more firmly. At this time, by adopting the one with a large amount of protrusion radially outward for the outermost core piece 2, not only the end face on the groove portion 5 side of the core piece 2 but also the side surface of the core piece 2 is fixed with the ultraviolet curable resin 6, so that the possibility of the core piece 2 peeling off can be reduced.

[0048] Also, as shown as another lamination example No. 2, it is possible to adopt a configuration in which a plurality of core pieces 2 having different shapes of the concave portions 5a are laminated. Also with such a configuration, a step in the radial direction is formed on the surface of the groove portion 5, and by injecting and curing the ultraviolet curable resin 6 in a state of covering the step, the step can generate a so-called anchor effect to fix each core piece 2 more firmly.

[0049] Also, as shown as another lamination example No. 3, those having different widths of the concave portions 5a in the circumferential direction, or those having different shapes of the concave portions 5a with respect to both the radial direction and the circumferential direction are alternately laminated, or laminated every predetermined number of sheets, and the surface of the groove portion 5 is formed into a shape having steps in the circumferential direction and the radial direction.

[0050] For example, the core piece 2 in which the concave portion 5a described in the embodiment is formed and the core piece 2 in which the concave portion 5a described in another shape example No. 1 is formed can be laminated. Alternatively, it is possible to adopt a configuration in which the core pieces 2 having three or more different shapes of the concave portions 5a among the concave portions 5a described in the embodiment and the concave portions 5a described in other shape examples are alternately laminated or laminated every predetermined number of sheets.

[0051] Also with such a configuration, by injecting and curing the ultraviolet curable resin 6 in a state of covering the step thereof, the step can generate a so-called anchor effect to fix each core piece 2 more firmly.

[0052] In addition, in the embodiment, the procedure of separately injecting and curing the ultraviolet curable resin 6 was exemplified. However, as shown in FIG. 9 as another manufacturing mode 1 for example, the dispenser 10 and the irradiation device 11 can be operated in conjunction with respect to the same groove portion 5, and the ultraviolet curable resin 6 can be cured while being injected.

[0053] Further, as shown in FIG. 10 as another manufacturing mode 2, for example, the ultraviolet curable resin 6 is simultaneously injected into the diagonally located groove portions 5, and the dispenser 10 and the irradiation device 11 are moved in the circumferential direction shown in the figure to cure the injected ultraviolet curable resin 6 while injecting the ultraviolet curable resin 6 into the adjacent groove portion 5, and then the dispenser 10 and the irradiation device 11 can be further moved in the circumferential direction shown in the figure.

[0054] Alternatively, as shown in FIG. 10 as another manufacturing mode 2, the ultraviolet curable resin 6 is cured while being injected into the two diagonally located groove portions 5 as shown in FIG. 9, and then the dispenser 10 and the irradiation device 11 are moved in the circumferential direction shown in the figure to inject and cure the ultraviolet curable resin 6 with respect to the next two groove portions 5. Thereby, the injection and curing of the ultraviolet curable resin 6 can be efficiently performed, and the working efficiency can be greatly improved.

[0055] In this case, the dispenser 10 and the irradiation device 11 can be configured to be moved by a robot. Further, when the manufacturing modes shown in FIGS. 9 and 10 are adopted, the pressurization during injection shown in FIG. 4 is not performed, the pressurization during curing is performed after the flash removal process, and the ultraviolet curable resin 6 can be injected and cured in that state.

[0056] A configuration can be adopted in which the surface of the stator core 1 is varnished or a process for suppressing scattering is applied to the surface of the ultraviolet curable resin 6 provided in the groove portion 5. Further, it can be applied to the manufacture of the stator core 1 not provided with the ear portions 4.

[0057] In addition, although the manufacturing of the stator core 1 has been described as an example in the embodiment, the core manufacturing method can be applied to the manufacturing of the rotor core. In that case, by injecting and curing the ultraviolet curable resin 6 on the inner peripheral side of the rotor core, that is, the side where the shaft is inserted, the risk of the ultraviolet curable resin 6 scattering during rotation can be reduced.

[0058] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and its equivalent scope.

Explanation of Reference Numerals

[0059] In the drawings, 1 represents a stator core, 2 represents a core piece, 3 represents a laminate, 5 represents a groove portion, 5a represents a recess, and 6 represents an ultraviolet curable resin.

Claims

1. A step of forming a laminate by laminating thin plate-shaped core pieces each having a recess recessed inwardly formed on an outer peripheral portion thereof; A step of injecting an ultraviolet curable resin into a groove portion formed to extend in the lamination direction on an outer peripheral surface of the laminate within a range not protruding from the groove portion; A step of irradiating the injected ultraviolet curable resin with ultraviolet rays to cure the ultraviolet curable resin, and including: While applying pressure in the lamination direction to the laminate, injecting the ultraviolet curable resin into the groove portion and irradiating the injected ultraviolet curable resin with ultraviolet rays, and A method of manufacturing a core, wherein a pressure applied when injecting the ultraviolet curable resin is made smaller than a pressure applied when irradiating the ultraviolet curable resin with ultraviolet rays.

2. The method of manufacturing a core according to claim 1, wherein the core pieces having different shapes of the recesses are laminated to form the laminate.

3. Laminating the core pieces provided with a plurality of the recesses, The method of manufacturing a core according to claim 1 or 2, wherein the ultraviolet curable resin is injected and irradiated with ultraviolet rays simultaneously to two or more of the groove portions formed in the laminate.

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