JP2018037572A - Wound core, and manufacturing method of wound core - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress cracking of a steel sheet during manufacture of a wound core, while reducing iron loss of the wound core.SOLUTION: In a wound core formed by winding a directional magnetic steel sheet 10, where grooves D1 are formed at a prescribed interval in the transport direction of magnetic steel sheet by irradiating a laser beam in a direction crossing the transport direction, formation state of the grooves D1 at a corner of the wound core is different from formation state of the grooves D1 at the part of the wound core other than the corner. In a part 32 other than the corner, a first groove extending in the plate width direction of the magnetic steel sheet is formed, and no groove is formed in a corner corresponding part 34.SELECTED DRAWING: Figure 8

Description

  The present invention relates to a wound iron core manufactured using a grain-oriented electrical steel sheet having grooves formed by laser beam irradiation, and a method for manufacturing the wound iron core.

  The grain-oriented electrical steel sheet has a low energy loss (iron loss) when magnetized with a relatively small magnetizing force, and is used, for example, when manufacturing a wound iron core of a transformer. The surface of the grain-oriented electrical steel sheet is usually coated with an insulating film. Thereby, the insulation between the steel plate layers in a wound iron core is ensured.

  In the grain-oriented electrical steel sheet, it is required to further reduce iron loss. As a measure for improving such iron loss, a method of forming a groove in a steel sheet has been performed.

  For example, as disclosed in Patent Document 1 below, there is a method of forming a groove by electrolytic etching. In such a method, for example, a steel sheet having a glass film formed on the surface after secondary recrystallization is used, and the glass film on the surface is linearly removed by a laser or a mechanical method, and a groove is formed in a portion where the ground iron is exposed by etching. Form. However, in the electrolytic etching method, the process is complicated, the manufacturing cost increases, and the processing speed is limited.

  Further, as disclosed in Patent Document 2, there is a method of forming grooves by a mechanical tooth type press. However, in such a method, the electromagnetic steel plate is a very hard steel plate containing about 3% Si, so that tooth wear and damage are likely to occur. When the tooth mold is worn, the groove depth varies, and the iron loss improvement effect becomes non-uniform.

  As a method for solving the problems of the above-described method, as disclosed in Patent Documents 3 and 4, there is a method of forming a groove by irradiating a steel plate with a laser beam. In this method, high-speed grooving can be performed with a high-power density focused laser beam. Further, since it is non-contact processing, stable and uniform groove processing can be performed by controlling laser power and the like.

Japanese Patent Publication No.62-54873 Japanese Examined Patent Publication No. 62-53579 JP-A-6-57335 JP 2003-129135 A

  By the way, when a groove is formed by irradiating a laser beam, a melt or a melt re-solidified product (hereinafter referred to as a melt or the like) is generated in the groove of the steel plate. When such a melt or the like occurs, stress tends to concentrate. In such a case, the directional electromagnetic steel sheet may be cracked when bending the directional electromagnetic steel sheet during the manufacture of the wound iron core.

  Therefore, the present invention has been made in view of the above problems, and the object of the present invention is to reduce the iron loss of the wound iron core and to prevent the occurrence of cracks in the steel sheet during the production of the wound iron core. It is to suppress.

  In order to solve the above-described problems, according to one aspect of the present invention, there is provided a grain-oriented electrical steel sheet that is irradiated with a laser beam in a direction intersecting a transport direction of the steel sheet and grooves are formed at predetermined intervals in the transport direction. A wound iron core formed by winding, characterized in that the groove forming state in the corner portion of the wound iron core is different from the groove forming state in the portion other than the corner portion of the wound iron core, A wound core is provided.

  Further, in the wound iron core, a first groove having an extending direction parallel to a plate width direction of the steel plate is formed in a portion other than the corner portion, and the first groove is formed in the corner portion. It does not have to be.

  In the wound iron core, a first groove is formed in a portion other than the corner portion so that the extending direction is parallel to the plate width direction of the steel plate, and the extending direction is the plate in the corner portion. The second groove may be formed so as to intersect the width direction.

  In the wound iron core, the depth of the groove formed in the corner portion may be shallower than the depth of the groove formed in a portion other than the corner portion.

  In the wound iron core, the depth of the grooves formed at predetermined intervals in the transport direction may be 0.2 times or more the width of the grooves.

  In order to solve the above-mentioned problem, according to another aspect of the present invention, a step of irradiating a laser beam in a direction intersecting with the conveying direction of the grain-oriented electrical steel sheet and forming grooves at predetermined intervals in the conveying direction; And a step of forming a wound iron core by winding the steel sheet with the groove formed thereon, the portion corresponding to a corner portion of the wound iron core of the grain-oriented electrical steel sheet The method for manufacturing a wound iron core is provided in which the groove formation state in the above is made different from the groove formation state in a portion other than the corner portion.

  As described above, according to the present invention, it is possible to suppress the occurrence of cracks in the steel sheet during the manufacture of the wound core while reducing the iron loss of the wound core.

It is sectional drawing which shows an example of a structure of the grain-oriented electrical steel plate 10 which concerns on this embodiment. It is a perspective view which shows an example of a structure of the wound iron core 50 which concerns on this embodiment. It is a schematic diagram which shows the state which expand | deployed several directionality electrical steel plates 10 which comprise the wound iron core 50 of FIG. It is a flowchart which shows an example of the manufacturing process of the wound iron core 50 which concerns on this embodiment. It is a schematic diagram which shows the structural example of the laser processing apparatus 100 which concerns on this embodiment. It is a schematic diagram which shows the formation state of the groove | channel D in the grain-oriented electrical steel sheet 900 which concerns on a comparative example. FIG. 3 is a schematic diagram showing a laser beam irradiation state in a corner corresponding part and a non-corner corresponding part 32 of the grain-oriented electrical steel sheet 10. FIG. 3 is a schematic diagram showing a groove formation state in the grain-oriented electrical steel sheet 10. 4 is a schematic diagram showing a first modification of groove formation in the grain-oriented electrical steel sheet 10. FIG. It is a schematic diagram which shows the 2nd modification of the groove formation in the grain-oriented electrical steel sheet 10.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

<Outline of grain-oriented electrical steel sheet>
A grain-oriented electrical steel sheet is an electrical steel sheet in which the easy axis of magnetization of the crystal grains of the steel sheet (the <100> direction of the body-centered cubic crystal) is substantially aligned with the rolling direction in the manufacturing process. The grain-oriented electrical steel sheet has a structure in which a plurality of magnetic domains whose magnetization is oriented in the rolling direction are arranged with a domain wall interposed therebetween. Such grain-oriented electrical steel sheets are easily magnetized in the rolling direction, and are therefore suitable as an iron core material for transformers in which the direction of the lines of magnetic force flows almost constant.

  Transformers are generally divided into loading transformers and winding transformers. The grain-oriented electrical steel sheet according to the present embodiment is used as an iron core material for a wound transformer that is assembled into a transformer shape while being wound into the steel sheet.

  FIG. 1 is a cross-sectional view showing an example of the configuration of a grain-oriented electrical steel sheet 10 according to this embodiment. As shown in FIG. 1, the grain-oriented electrical steel sheet 10 includes a steel sheet main body (ground iron) 12, a glass coating 14 formed on both surfaces of the steel sheet main body 12, an insulating coating 16 formed on the glass coating 14, Have

  The steel plate body 12 is made of an iron alloy containing Si. As an example, the composition of the steel sheet body 12 is Si: 2.5 mass% to 4.0 mass%, C: 0.02 mass% to 0.10 mass%, Mn: 0.05 mass% to 0.00 mass%. 20 mass% or less, acid-soluble Al; 0.020 mass% or more and 0.040 mass% or less, N: 0.002 mass% or more and 0.012 mass% or less, S; 0.001 mass% or more and 0.010 mass% or less Hereinafter, P: 0.01% by mass or more and 0.04% by mass or less, and the balance is Fe and inevitable impurities. The thickness of the steel plate body 12 is, for example, 0.15 mm or more and 0.35 mm or less.

  The glass coating 14 is made of a composite oxide such as forsterite (Mg2SiO4), spinel (MgAl2O4), and cordierite (Mg2Al4Si5O18). The thickness of the glass coating 14 is, for example, 1 μm.

  The insulating coating 16 is composed of, for example, a coating liquid mainly composed of colloidal silica and phosphate (magnesium phosphate, aluminum phosphate, etc.) or a coating liquid in which alumina sol and boric acid are mixed.

  The grain-oriented electrical steel sheet 10 having the above-described configuration is wound in a state where a plurality of sheets are stacked and used as a wound iron core 50 of a transformer (transformer) shown in FIG.

  FIG. 2 is a perspective view showing an example of the configuration of the wound iron core 50 according to the present embodiment. As shown in FIG. 2, the wound iron core 50 has a cubic shape, and a space is formed on the center side. The horizontal length of the outer periphery of the wound iron core 50 is A, the vertical length is B, and the depth length is C. Moreover, the horizontal length of the inner periphery of the wound iron core 50 is a, the vertical length is b, and the depth of the inner periphery is the same as the depth of the outer periphery. The wound iron core 50 has corner parts 52 bent at the four corners at the time of manufacture. The corner portion 52 has an R shape, for example. The wound iron core 50 is formed by stacking a plurality of grain-oriented electrical steel sheets 10, and as shown in FIG. 2 corresponds to the rolling direction of FIG. 3, and the Y direction of FIG. 2 corresponds to the sheet width direction of FIG.

  FIG. 3 is a schematic diagram showing a state in which a plurality of grain-oriented electrical steel sheets 10 constituting the wound iron core 50 of FIG. 2 are developed. In FIG. 3, the wound iron core 50 is manufactured by winding N directional electromagnetic steel sheets 10. 3 is located on the outermost side in the wound iron core 50, and the directional electromagnetic steel sheet 10-N is located on the innermost side in the wound iron core 50. The lengths in the rolling direction of the N directional electromagnetic steel sheets 10 are different from each other. As shown in FIG. 3, the length in the rolling direction becomes shorter as the inner grain-oriented electrical steel sheet.

  In the grain-oriented electrical steel sheet 10, in order to further reduce iron loss, a groove extending in a direction intersecting with the conveying direction (rolling direction) at the time of manufacture of the grain-oriented electrical steel sheet 10 is a steel sheet body (base iron) 12. Are formed at predetermined groove intervals in the rolling direction. Although the details will be described later, the groove is formed by irradiating the surface of the steel bar with a laser beam by a laser processing apparatus.

<Method for manufacturing wound core>
A method for manufacturing the wound iron core 50 according to the present embodiment will be described with reference to FIG. FIG. 4 is a flowchart showing an example of a manufacturing process of the wound core 50 according to the present embodiment.

  As shown in FIG. 4, the manufacturing process of the wound core 50 includes a casting process S2, a hot rolling process S4, an annealing process S6, a cold rolling process S8, a decarburizing annealing process S10, and an annealing separator. It includes a coating step S12, a final finish annealing step S14, an insulating coating forming step S16, a laser irradiation step S18, an insulating coating forming step S20, and a steel sheet winding step S30.

  In the casting step S2, the molten steel adjusted to a predetermined composition is supplied to a continuous casting machine to continuously form an ingot. In the hot rolling step S4, the ingot is heated to a predetermined temperature (for example, 1150 to 1400 ° C.) to perform hot rolling. Thereby, a hot-rolled material having a predetermined thickness (for example, 1.8 to 3.5 mm) is formed.

  In the annealing step S6, the hot-rolled material is heat-treated, for example, under conditions of a heating temperature of 750 to 1200 ° C. and a heating time of 30 seconds to 10 minutes. In the cold rolling step S8, the surface of the hot rolled material is pickled and then cold rolled. Thereby, a cold-rolled material having a predetermined thickness (for example, 0.15 to 0.35 mm) is formed.

  In the decarburization annealing step S10, the cold-rolled material is heat-treated, for example, under conditions of a heating temperature of 700 to 900 ° C. and a heating time of 1 to 3 minutes to form a steel plate body. An oxide layer mainly composed of silica (SiO 2) is formed on the surface of the steel plate body 12. In the annealing separator application step S12, an annealing separator mainly composed of magnesia (MgO) is applied on the oxide layer of the steel plate body 12.

  In the final finish annealing step S14, the steel sheet main body 12 coated with the annealing separator is wound in a coil shape and inserted into a batch furnace to perform heat treatment. The heat treatment conditions are, for example, a heating temperature of 1100 to 1300 ° C. and a heating time of 20 to 24 hours. At this time, so-called goth grains in which the rolling direction of the steel plate body 12 and the easy magnetization axis coincide with each other preferentially grow. As a result, a grain-oriented electrical steel sheet having high crystal orientation (crystal orientation) after finish annealing is obtained. In addition, in the final finish annealing step S <b> 14, the oxide layer and the annealing separator react to form a glass film 14 made of forsterite (Mg2SiO4) on the surface of the steel plate body 12.

  In the insulating coating forming step S16, the steel sheet body 12 wound in a coil shape is unwound and stretched into a plate shape and conveyed. And an insulating agent is apply | coated and baked on the glass film 14 formed in both surfaces of the steel plate main body 12, and the insulating film 16 is formed. The steel plate body 12 on which the insulating coating 16 is formed is wound up in a coil shape.

  In the laser irradiation step S18, the steel sheet body 12 wound in a coil shape is unwound and stretched into a plate shape and conveyed. Then, a laser beam is focused and irradiated toward one surface of the steel sheet main body 12 by a laser irradiation apparatus to be described later, and scanned in the crossing direction intersecting the rolling direction of the electromagnetic steel sheet conveyed in the rolling direction. Thereby, the groove | channel extended in the cross direction is formed in the surface of the steel plate main body 12 at predetermined intervals in the rolling direction. In addition, you may perform condensing and irradiation of a laser beam from both the surface of the steel plate main body 12, and a back surface.

  In the insulating coating forming step S20, the insulating coating 16 is formed on the steel plate body 12 with the grooves formed in the same manner as in the insulating coating forming step S16. That is, the second insulating film 16 is formed. Through the above-described series of steps, a grain-oriented electrical steel sheet is manufactured in which grooves extending in a direction intersecting the rolling direction are formed on the surface of the steel sheet body (base iron) at a predetermined groove interval in the rolling direction.

  In this way, the glass coating 14 and the insulating coating 16 are formed on the surface of the steel plate body 12, and the grain-oriented electrical steel plate 10 whose magnetic domain is controlled by laser irradiation is manufactured. That is, the above-described steps S <b> 2 to S <b> 20 are manufacturing steps for the grain-oriented electrical steel sheet 10.

  In the steel sheet winding step S30, first, the grain-oriented electrical steel sheet 10 in which the grooves are formed is cut by a predetermined length in the rolling direction to prepare a plurality of sheets. And the wound iron core 50 shown in FIG. 2 is manufactured by winding in the state which piled up the several directionality electromagnetic steel plate 10.

  In the above description, the laser irradiation step S18 is performed after the insulating film forming step S16. However, the present invention is not limited to this, and the laser irradiation step S18 may be performed before the insulating film forming step S16. For example, the laser irradiation step S18 may be performed after the cold rolling step S8. Moreover, laser irradiation process S18 may be performed after decarburization annealing process S10. Further, the laser irradiation step S18 may be performed after the final finish annealing step S14. In such a case, since the insulating coating forming step S16 is performed after the laser irradiation step S18, the second insulating coating forming step S20 becomes unnecessary, and the manufacturing process can be shortened.

<Configuration of laser processing equipment>
A configuration example of the laser processing apparatus 100 that forms grooves by irradiating the grain-oriented electrical steel sheet 10 with a laser beam will be described with reference to FIG. FIG. 5 is a schematic diagram illustrating a configuration example of the laser processing apparatus 100 according to the present embodiment.

  The laser processing apparatus 100 irradiates a laser beam in an intersecting direction intersecting with the rolling direction from above the insulating coating 16 of the grain-oriented electrical steel sheet 10 conveyed at a constant speed in the rolling direction, thereby forming grooves extending in the intersecting direction. Form. The intersecting direction is a direction intersecting with the sheet thickness direction of the steel sheet. As shown in FIG. 5, the laser processing apparatus 100 includes a plurality of laser oscillators 102, transmission fibers 104, and laser irradiation apparatuses 106. In FIG. 5, three laser oscillators 102, a transmission fiber 104, and a laser irradiation device 106 are shown, but the configuration is the same.

  The laser oscillator 102 emits a high-power laser beam, for example. The transmission fiber 104 is an optical fiber that transmits the laser beam emitted from the laser oscillator 102 to the laser irradiation device 106.

  As the type of the laser oscillator 102, a fiber laser or a disk laser is preferable from the viewpoint of excellent minute focusing characteristics and the ability to form a narrow groove. A fiber laser or a disk laser has a wavelength in the near-ultraviolet region to the near-infrared region (for example, 1 μm band), so that the laser beam can be transmitted by an optical fiber, and the laser beam is transmitted by an optical fiber to be relatively compact. The laser processing apparatus 100 can be realized. The laser oscillator 102 may be a continuous wave laser or a pulsed laser.

  The laser irradiation device 106 causes the directional electromagnetic steel sheet 10 to focus and scan the laser beam transmitted from the laser oscillator 102 through the transmission fiber 104. Here, the condensing shape of the laser beam is an elliptical shape, for example, from the viewpoint of suppressing the generation of a melt accompanying laser irradiation. The width that one laser irradiation device 106 can scan the laser beam may be smaller than the plate width of the grain-oriented electrical steel sheet 10, but a plurality of laser irradiation devices 106 are arranged in the plate width direction as shown in FIG. Thus, the laser beam can be scanned over the entire width of the grain-oriented electrical steel sheet 10.

  In the above description, the condensing shape of the laser beam on the grain-oriented electrical steel sheet 10 is an elliptical shape, but is not limited to this. For example, the condensing shape of the laser beam may be a perfect circle.

In the above description, the laser oscillator 102 is a fiber laser or a disk laser. However, the present invention is not limited to this. For example, the laser oscillator 102 may be a CO ₂ laser.

<Occurrence of cracks associated with bending of steel sheet during winding transformer production>
The grain-oriented electrical steel sheet in which the groove is formed is used as an iron core (winding iron core) of a winding transformer. And at the time of manufacture of a wound iron core, bending of a grain-oriented electrical steel sheet is performed. During such bending, the steel sheet may break due to the grooves.

  Here, as a comparative example, as shown in FIG. 6, a directional electrical steel sheet in which a groove D perpendicular to the rolling direction (in other words, a groove D parallel to the sheet width direction) is formed is taken as an example. The cracking of will be described.

  FIG. 6 is a schematic diagram showing a formation state of the groove D in the grain-oriented electrical steel sheet 900 according to the comparative example. In bending a grain-oriented electrical steel sheet, the rolling direction of the steel sheet is usually bent. In FIG. 6, a groove D is formed in a corner corresponding portion 910 corresponding to the corner portion of the wound iron core in the directional electromagnetic steel plate 900 in parallel to the plate width direction of the steel plate. The length in the rolling direction of the corner corresponding portion 910 is the length L. Although FIG. 6 shows that only one groove is formed in the corner corresponding portion 910 having a length L, a plurality of grooves are actually formed. Thus, when the groove D is formed in the corner corresponding part 910 in parallel with the plate width direction of the steel plate, the width direction of the groove D is the same as the bending direction, so that the possibility of occurrence of cracks in the steel plate is increased. .

  The cause of the cracking of the steel sheet includes a melt or a melt re-solidified product (hereinafter referred to as a melt) generated in the groove of the steel sheet when the groove D is formed by irradiating a laser beam. When such a melt or the like is generated, stress tends to be concentrated, and therefore, the possibility that the steel plate will break when bending the steel plate is increased.

  In the grain-oriented electrical steel sheet, the groove D may be formed deep from the viewpoint of improving iron loss. In such a case, the ratio of the depth of the groove to the width of the groove increases, and cracking is likely to occur.

<Measures to suppress cracking of steel sheet>
In order to prevent the above-described cracking of the steel sheet, in the grain-oriented electrical steel sheet 10 according to the present embodiment, a groove formation state in a portion corresponding to the corner portion 52 (hereinafter also referred to as a corner corresponding portion) of the wound core 50 However, it is different from the groove formation state in a portion corresponding to a portion other than the corner portion 52 of the wound core 50 (hereinafter also referred to as a non-corner corresponding portion). An example of the groove formation state will be described with reference to FIGS.

  FIG. 7 is a schematic diagram showing a laser beam irradiation state in the corner corresponding portion 34 and the non-corner corresponding portion 32 of the grain-oriented electrical steel sheet 10. FIG. 8 is a schematic diagram showing a groove formation state in the grain-oriented electrical steel sheet 10. The corner corresponding portion 34 is a region having a length L in the rolling direction of the grain-oriented electrical steel sheet 10. Note that the grain-oriented electrical steel sheet 10-1 and the like shown in FIG. 3 are obtained by cutting a part of the rolling direction of the grain-oriented electrical steel sheet 10 shown in FIG.

  In this embodiment, as shown in FIG. 8, the non-corner corresponding portion 32 is formed with a parallel groove D1 whose extending direction is parallel to the plate width direction of the steel plate. On the other hand, no parallel groove is formed in the corner corresponding portion 34. Specifically, as shown in FIG. 7, by turning off the operation of the laser irradiation device 106 for the corner corresponding portion 34, no groove is formed in the corner corresponding portion 34.

  By not forming the groove in the corner corresponding portion 34, it is possible to effectively prevent the steel plate from being cracked by the groove. On the other hand, the corner-corresponding portion 34 is sufficiently smaller than the non-corner-corresponding portion 32, so that the groove is formed in the non-corner-corresponding portion 32 without forming the groove in the corner-corresponding portion 34. The reduction in the effect of improving the iron loss of 50 can be suppressed. Therefore, according to this embodiment, generation | occurrence | production of the crack of the directionality electromagnetic steel plate 10 at the time of manufacture of the wound iron core 50 can be suppressed, reducing the iron loss of the wound iron core 50. FIG. In FIG. 8, the groove is shown as a single line connected in the plate width direction over the entire region. However, the present invention is not limited to this, and the groove may be formed intermittently in the plate width direction. .

  By the way, in order to improve iron loss improvement, it turns out that it is effective to deepen a groove | channel. Therefore, in this embodiment, the groove is formed so as to increase the depth without increasing the width. For example, the depth of the groove is 0.2 times or more the width of the groove. Specifically, the depth of the groove is about 20 μm.

  When the groove D having such a large depth is formed, the steel sheet may be cracked during bending of the grain-oriented electrical steel sheet. On the other hand, even if the depth of the groove is large, bending is performed by not forming the parallel groove D1 in the portion corresponding to the corner portion 52 of the wound core 50 of the grain-oriented electrical steel sheet as in this embodiment. It is possible to effectively suppress the occurrence of cracks in the steel sheet during the process.

  In the above description, the parallel grooves D1 are formed in the non-corner corresponding portions 32, while the grooves are not formed in the corner corresponding portions 34. However, the present invention is not limited to this. For example, grooves may be formed as shown in FIGS.

  FIG. 9 is a schematic diagram illustrating a first modification of groove formation in the grain-oriented electrical steel sheet 10. Also in the first modification, the non-corner corresponding portion 32 is formed with a parallel groove D1 whose extending direction is parallel to the plate width direction, as in FIG. On the other hand, unlike the case of FIG. 8, a parallel groove D <b> 2 is formed in the corner corresponding portion 34. Here, the depth of the parallel groove D2 formed in the corner corresponding part 34 is shallower than the depth of the parallel groove D1 formed in the non-corner corresponding part 32. In the first modification, the parallel groove D1 corresponds to the first groove, and the parallel groove D2 corresponds to the second groove.

  When the groove is shallower, cracks are less likely to occur when the steel plate is bent. For this reason, by forming the shallow groove D <b> 2 in the corner corresponding part 34, it is possible to suppress the occurrence of bending of the steel sheet due to the groove D <b> 2 when the wound core 50 is manufactured. The parallel groove D2 is formed by reducing the intensity of the laser beam irradiated by the laser irradiation device 106 (see FIG. 9). That is, the parallel groove D1 and the parallel groove D2 can be formed by one laser irradiation device 106.

  FIG. 10 is a schematic diagram illustrating a second modification of groove formation in the grain-oriented electrical steel sheet 10. Also in the second modified example, the non-corner corresponding portion 32 is formed with a parallel groove D1 whose extending direction is parallel to the plate width direction, as in FIG. On the other hand, unlike the case shown in FIG. 8, the corner corresponding part 34 is formed with an inclined groove D <b> 3 whose extending direction intersects the plate width direction. In the second modification, the parallel groove D1 corresponds to the first groove, and the inclined groove D3 corresponds to the second groove.

  Since the extending direction of the inclined groove D3 intersects the sheet width direction perpendicular to the bending direction at the time of bending the steel sheet (in other words, the width direction of the inclined groove D3 is not the same direction as the bending direction), the wound iron Generation of cracks in the steel sheet due to the inclined groove D3 can be suppressed when the core 50 is manufactured. Here, a larger angle θ (also referred to as an inclination angle of the inclined groove) θ between the extending direction of the inclined groove and the plate width direction is effective in preventing cracking of the steel sheet. In the present embodiment, the inclined grooves are formed so that the inclination angle θ is 15 degrees or more. In addition, the parallel groove | channel D1 and the inclination groove | channel D3 which are shown in FIG.

<Example>
Examples for confirming the effectiveness of the grain-oriented electrical steel sheet according to the present embodiment described above will be described.

The grain-oriented electrical steel sheet according to this example is manufactured as follows.
First, Si: 3.0% by mass, C: 0.05% by mass, Mn: 0.1% by mass, acid-soluble Al: 0.02% by mass, N: 0.01% by mass, S: 0.01% by mass %, P; 0.02 mass%, and a slab having a composition of the balance being Fe and inevitable impurities was prepared. The slab was hot rolled at 1280 ° C. to produce a hot rolled material having a thickness of 2.3 mm. Next, heat treatment was performed on the hot-rolled material under conditions of 1000 ° C. × 1 minute. After the heat treatment, the steel sheet was pickled and then cold rolled to produce a cold rolled material having a thickness of 0.23 mm. The cold-rolled material was decarburized and annealed under conditions of 800 ° C. × 2 minutes. Next, the annealing separation material which has a magnesia as a main component was apply | coated to both surfaces of the cold-rolled material after decarburization annealing. And the cold rolled material which apply | coated the annealing separation material was charged in the batch type furnace in the state wound up in the shape of a coil, and finish annealing was implemented on the conditions of 1200 degreeC x 20 hours. Thereby, the steel plate base iron (steel plate main body 12) in which the glass film was formed on the surface was produced. Next, an insulating material made of aluminum phosphate was applied onto the glass coating 14 and baked (850 ° C. × 1 minute) to form a first insulating coating.

  Next, the steel plate body 12 on which the glass coating 14 and the insulating coating were formed was irradiated with a laser beam to form grooves on the surface of the steel plate body 12. At this time, for example, as shown in FIG. 8, the non-corner corresponding portion 32 of the grain-oriented electrical steel sheet 10 may be formed with the parallel groove D <b> 1 and the corner corresponding portion 34 may not be formed with a groove. Alternatively, a shallow groove D2 may be formed in the corner corresponding portion 34 as shown in FIG. 9, or an inclined groove D3 may be formed in the corner corresponding portion 34 as shown in FIG.

  Here, the laser irradiation apparatus 106 shown in FIG. 5 was used as the laser irradiation apparatus. As irradiation conditions, the laser beam intensity was 1000 W, the beam scanning speed was 30 m / s, and the irradiation pitch was 3 mm. The shape of the laser beam is elliptical, the rolling direction of the beam diameter is 0.1 mm, and the scanning direction of the beam diameter is 0.3 mm. Under such irradiation conditions, a groove having a width of 50 μm and a depth of 20 μm was formed.

  Next, a second insulating film was formed on the steel plate body 12 in which the grooves were formed. Thereby, the grain-oriented electrical steel sheet 10 as shown in FIG. 1 is manufactured. And after cutting the directionality electrical steel plate 10 in which the groove | channel was formed only predetermined length in the rolling direction, it winds in the state which accumulated several directionality electromagnetic steel plates 10, and showed the wound iron core shown in FIG. 50 is manufactured.

<Summary>
As described above, in the grain-oriented electrical steel sheet 10 according to the present embodiment, the groove formation state in the corner corresponding portion 34 corresponding to the corner portion 52 of the wound iron core 50 is a portion other than the corner portion 52 of the wound iron core 50. It differs from the formation state of the groove | channel in the non-corner corresponding | compatible part 32 corresponding to this.

  Specifically, the parallel groove D <b> 1 is formed in the non-corner corresponding part 32, while the groove is not formed in the corner corresponding part 34. Alternatively, the shallow groove D2 is formed in the corner corresponding part 34, or the inclined groove D3 is formed in the corner corresponding part 34. Thereby, it can suppress that the crack of a steel plate generate | occur | produces at the time of manufacture of the wound iron core 50 by the groove | channel formed in the corner corresponding | compatible part 34. FIG. On the other hand, since the corner corresponding part 34 is only a small area in the wound iron core 50, the groove is formed in the non-corner corresponding part 32 without forming the groove in the corner corresponding part 34. A decrease in the effect of improving the iron loss of the iron core 50 can be suppressed. Therefore, according to this embodiment, generation | occurrence | production of the crack of the grain-oriented electrical steel sheet 10 at the time of manufacture of the wound iron core 50 can be suppressed, reducing the iron loss of the wound iron core 50. FIG.

  The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can come up with various changes or modifications within the scope of the technical idea described in the claims. Of course, it is understood that these also belong to the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 10 Directional electrical steel sheet 12 Steel plate main body 14 Glass coating 16 Insulation coating 32 Non-corner corresponding part 34 Corner corresponding part 50 Coil core 52 Corner part 100 Laser processing apparatus 102 Laser oscillator 104 Transmission fiber 106 Laser irradiation apparatus D1, D2, D3 Groove

Claims (6)

A wound iron core formed by irradiating a laser beam in a direction intersecting with the conveying direction of the steel sheet and winding a directional electromagnetic steel sheet having grooves formed at predetermined intervals in the conveying direction,
A wound iron core, wherein a groove is formed in a corner portion of the wound core different from a groove formed in a portion other than the corner portion of the wound core. In the wound iron core according to claim 1,
In a portion other than the corner portion, a first groove whose extending direction is parallel to the plate width direction of the steel plate is formed,
The wound iron core is characterized in that the first groove is not formed in the corner portion. In the wound iron core according to claim 1,
In a portion other than the corner portion, a first groove is formed so that the extending direction is parallel to the plate width direction of the steel plate,
The wound iron core is characterized in that a second groove is formed in the corner portion so that the extending direction intersects the plate width direction. In the wound iron core according to claim 1,
The wound core is characterized in that the depth of the groove formed in the corner portion is shallower than the depth of the groove formed in a portion other than the corner portion. In the wound iron core according to any one of claims 1 to 4,
The wound iron core characterized in that the depth of the grooves formed at predetermined intervals in the conveying direction is 0.2 times or more the width of the grooves. Irradiating a laser beam in a direction intersecting the conveying direction of the grain-oriented electrical steel sheet, and forming grooves at a predetermined interval in the conveying direction;
A step of winding the steel sheet on which the groove is formed to form a wound iron core;
A method of manufacturing a wound iron core comprising:
A method for producing a wound iron core, characterized in that a groove formation state in a portion corresponding to a corner portion of the wound iron core of the grain-oriented electrical steel sheet is different from a groove formation state in a portion other than the corner portion. .

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