JP2018035412A - Method for producing grain oriented silicon steel sheet, and grain oriented silicon steel sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the generation of the cracks upon bending in a grain oriented silicon steel sheet while reducing the core loss of the grain oriented silicon steel sheet.SOLUTION: Provided is a method for producing a grain oriented silicon steel sheet comprising a process where laser beams are applied to a direction crossed with the carrying direction of a steel sheet to form grooves at prescribed intervals to the carrying direction, in which first grooves in which the stretching direction is formed in parallel with the sheet width direction of the steel sheet and second grooves in which the stretching direction is formed so as to be crossed with the sheet width direction are formed so as to be mixed in the sheet width direction.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a method of manufacturing a grain-oriented electrical steel sheet that forms grooves by irradiating a laser beam, and to a grain-oriented electrical steel sheet.

  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 an object of the present invention is to generate cracks during bending of the directional electromagnetic steel sheet while reducing the iron loss of the directional electromagnetic steel sheet. It is to suppress.

  In order to solve the above problems, according to one aspect of the present invention, a directional electromagnetic wave including a step of irradiating a laser beam in a direction intersecting a conveyance direction of a steel sheet and forming grooves at a predetermined interval in the conveyance direction. A method for manufacturing a steel sheet, comprising: a first groove whose extending direction is formed in parallel with the plate width direction of the steel sheet; and a second groove formed so that the extending direction intersects the plate width direction. A method for producing a grain-oriented electrical steel sheet is provided, wherein the grain-wise electrical steel sheet is formed so as to be mixed in the plate width direction.

  Moreover, in the manufacturing method of the grain-oriented electrical steel sheet, a first irradiation unit and a second irradiation unit that irradiate a laser beam are disposed along the plate width direction, and the first irradiation unit performs the first irradiation unit. A groove may be formed, and the second groove may be formed by the second irradiation unit.

  In the method for manufacturing a grain-oriented electrical steel sheet, the first groove and the second groove may be alternately formed in the plate width direction.

In the method for manufacturing a grain-oriented electrical steel sheet, the ratio A of the second groove of the first groove and the second groove is an angle θ between the second groove and the plate width direction. In this case, the following formula (1) may be satisfied.
Ratio A = −3.22 × angle θ + 110 (1)

Moreover, in the method for manufacturing the grain-oriented electrical steel sheet, further comprising a step of measuring a distribution of iron loss in the sheet width direction of the steel sheet before the step of irradiating the laser beam,
The first groove is preferentially formed in a portion where the iron loss is relatively large in the plate width direction, and the second groove is preferentially formed in a portion where the iron loss is relatively small in the plate width direction. Also good.

  In the method for manufacturing a grain-oriented electrical steel sheet, the depth of the groove may be 0.2 times or more the width of the groove.

  In order to solve the above-mentioned problem, according to another aspect of the present invention, a directional electromagnetic wave having grooves formed at predetermined intervals in the transport direction is irradiated with a laser beam in a direction intersecting the transport direction of the steel sheet. A first groove in which the extending direction is formed in parallel with the plate width direction of the steel sheet and a second groove formed so that the extending direction intersects the plate width direction are the steel plates. A grain-oriented electrical steel sheet is provided that is formed so as to be mixed in the width direction.

  As described above, according to the present invention, it is possible to suppress the occurrence of cracks during bending of the directional electromagnetic steel sheet while reducing the iron loss of the directional electromagnetic steel sheet.

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 flowchart which shows an example of the manufacturing process of the grain-oriented electrical steel sheet 10 which concerns on this embodiment. It is a flowchart which shows the example different from the example shown in FIG. 2 of the manufacturing process of the grain-oriented electrical steel plate 10 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 in the grain-oriented electrical steel sheet 900 which concerns on a comparative example. It is a schematic diagram which shows the formation state of the groove | channel in the grain-oriented electrical steel sheet 10 which concerns on this embodiment. FIG. 6 is a schematic diagram showing a modification of the formation state of grooves in the grain-oriented electrical steel sheet 10. It is a flowchart which shows the example different from the example shown in FIG.2 and FIG.3 of the manufacturing process of the grain-oriented electrical steel plate 10 which concerns on this embodiment. It is a graph which shows an example of the relationship between the inclination angle of a groove | channel, and the repetition bending average frequency | count of a steel plate. It is a graph which shows an example of the relationship between the inclination-angle of a groove | channel, and an iron loss improvement rate. It is a graph which shows an example of the relationship between the ratio of an inclination groove | channel, and the number of repeated bending averages. It is a graph which shows an example of the relationship between the inclination-angle of an inclination groove | channel, and the ratio of an inclination groove | channel.

  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 used for a wound iron core of a transformer (transformer), and intersects the conveying direction (rolling direction) at the time of manufacturing the grain-oriented electrical steel sheet 10 in order to further reduce iron loss. Grooves extending in the direction are formed on the surface of the steel plate body (base iron) 12 at a predetermined groove interval 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 producing grain-oriented electrical steel sheet>
The manufacturing method of the grain-oriented electrical steel sheet 10 according to the present embodiment will be described with reference to FIG. FIG. 2 is a flowchart showing an example of a manufacturing process of the grain-oriented electrical steel sheet 10 according to this embodiment.

  As shown in FIG. 2, the manufacturing process of the grain-oriented electrical steel sheet 10 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 separation. An agent coating step S12, a final finish annealing step S14, an insulating film forming step S16, a laser irradiation step S18, and an insulating film forming step S20 are included.

  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. Then, a wound iron core is manufactured by winding the manufactured directional electromagnetic steel sheets 10 in a state of being stacked.

  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, in the manufacturing process of the grain-oriented electrical steel sheet 10, as shown in FIG. 3, the laser irradiation process S18 may be performed after the cold rolling process S8. In such a case, as shown in FIG. 3, since the insulating coating forming step S16 is performed after the laser irradiation step S18, the second insulating coating forming step S20 can be omitted from the manufacturing process of the grain-oriented electrical steel sheet 10. Manufacturing process can be shortened. 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. Even 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. 4 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. 4, the laser processing apparatus 100 includes a plurality of laser oscillators 102, transmission fibers 104, and laser irradiation apparatuses 106. In FIG. 4, three laser oscillators 102, a transmission fiber 104, and a laser irradiation device 106 are shown, but each 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 this embodiment, as the laser irradiation device 106, the laser irradiation device 106A and the laser irradiation device 106B are alternately arranged along the plate width direction. The laser irradiation device 106A forms a groove (hereinafter also referred to as a parallel groove) D1 whose extending direction is parallel to the plate width direction of the steel sheet. Specifically, the laser irradiation device 106A forms the parallel groove D1 by scanning the laser beam at least once in a direction parallel to the plate width direction. The laser irradiation device 106B forms a groove (hereinafter also referred to as an inclined groove) D2 whose extending direction intersects the sheet width direction of the steel sheet. Specifically, the laser irradiation device 106B forms the inclined groove D2 by scanning the laser beam at least once in a direction crossing the plate width direction. Thereby, the parallel grooves D1 and the inclined grooves D2 are alternately formed in the plate width direction. In the present embodiment, the parallel groove D1 corresponds to the first groove, and the inclined groove D2 corresponds to the second groove. Further, the laser irradiation device 106A corresponds to the first irradiation unit, and the laser irradiation device 106B corresponds to the second irradiation unit. The reason why the parallel grooves D1 and the inclined grooves D2 are mixed in the plate width direction will be described later.

  Further, the plurality of grooves formed by the plurality of laser irradiation devices 106 are formed intermittently along the plate width direction so as to be separated from each other, for example. Specifically, the parallel grooves D1 and the inclined grooves D2 can be intermittently formed along the plate width direction so as to be separated from each other. In that case, a groove portion that is bent to form a predetermined angle by joining adjacent grooves is not formed. In the following, an example in which a plurality of grooves are formed in the grain-oriented electrical steel sheet 10 so as to be separated from each other will be mainly described. However, the present invention is not limited to this example, and the relative relationship between the laser irradiation device 106 and the grain-oriented electrical steel sheet 10 is described. Due to the relationship, the plurality of grooves may be formed in contact with each other or may be formed to cross each other.

  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. 5, a directional electrical steel sheet in which grooves perpendicular to the rolling direction (in other words, grooves parallel to the sheet width direction) D1 are formed is given as an example. The crack will be described.

  FIG. 5 is a schematic diagram showing a formation state of the groove D1 in the grain-oriented electrical steel sheet 900 according to the comparative example. In FIG. 5, four grooves D1 whose extending direction is parallel to the plate width direction are formed intermittently along the plate width direction. That is, the four grooves D1 are formed so that there is a slight gap in the rolling direction. In bending a grain-oriented electrical steel sheet, the rolling direction of the steel sheet is usually bent. For this reason, as shown in FIG. 5, when the groove D1 is formed in parallel to the sheet width direction of the steel sheet, the width direction of the groove D1 is the same as the bending direction, so that the steel sheet may be cracked. Rise.

  The cause of the cracking of the steel sheet includes a melt and a re-solidified product (hereinafter referred to as a melt) generated in the groove of the steel sheet when the groove D1 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 D1 may be formed deeply 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.

  In FIG. 5, the four grooves D1 are intermittently formed along the plate width direction, but the present invention is not limited to this. For example, even if the four grooves D1 are located at the same position in the rolling direction and are formed in a single line shape, the possibility of cracking of the steel sheet increases.

<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, grooves D1 and D2 as shown in FIG. 6 are formed at a predetermined interval PL in the rolling direction.

  FIG. 6 is a schematic diagram showing a groove formation state in the grain-oriented electrical steel sheet 10 according to the present embodiment. In the present embodiment, parallel grooves D1 whose extending direction is parallel to the sheet width direction of the steel sheet and inclined grooves D2 whose extending direction intersects the sheet width direction of the steel sheet are formed as the grooves. And the parallel groove | channel D1 and the inclination groove | channel D2 are mixed in the plate width direction of a steel plate, and are formed over the plate width whole region of a steel plate.

  Further, the parallel grooves D1 and the inclined grooves D2 are alternately arranged in the plate width direction. The parallel grooves D1 and the inclined grooves D2 are formed by different laser irradiation devices 106 arranged in the plate width direction. For example, the parallel groove D1 is formed by the laser irradiation device 106A shown in FIG. 4, and the inclined groove D2 is formed by the laser irradiation device 106B.

  When the inclined groove D2 is formed, the extending direction of the inclined groove D2 intersects the plate 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 is the bending direction). Therefore, it is possible to suppress cracking of the steel plate when the steel plate is bent. 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 inclination angle θ of the inclined groove is, for example, 20 degrees.

  On the other hand, when the inclined groove D2 is formed, cracking of the steel sheet can be suppressed, while the effect of improving the iron loss may be reduced. In particular, the greater the groove inclination angle θ, the lower the effect of iron loss improvement. This is because in the case of inclined grooves, the generation of magnetic poles is reduced compared to grooves perpendicular to the rolling direction.

  Therefore, in this embodiment, not only the inclined grooves D2 are formed, but the parallel grooves D1 and the inclined grooves D2 are mixedly arranged in the plate width direction, so that cracks during bending of the grain-oriented electrical steel sheet 10 occur. It is possible to suppress a decrease in the effect of iron loss improvement while preventing the above. In particular, in this embodiment, by arranging the parallel grooves D1 and the inclined grooves D2 alternately in the plate width direction, the length in the extending direction of the parallel grooves D1 can be reduced, so that the above effect is more effectively achieved. Is done.

In FIG. 6, the parallel grooves D1 and the inclined grooves D2 are formed at the same ratio. However, the present invention is not limited to this, and it is derived from an experimental example described later that the ratio of the inclined groove D2 changes according to the inclination angle θ of the inclined groove D2. Specifically, in order to exhibit the above-described effect, it is desirable that the ratio A (%) of the inclined groove D2 is set as the following approximate expression (1).
Ratio A = −3.22 × tilt angle θ + 110 (1)

  By the way, in order to improve iron loss improvement, it turns out that it is effective to deepen a groove | channel. Therefore, in the present embodiment, grooves (parallel grooves D1 and inclined grooves D2) are 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 a groove 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, by forming the parallel grooves D1 and the inclined grooves D2 in the plate width direction as in the present embodiment, even if the depth of the grooves is large, the cracking of the steel plate during bending is caused. Generation can be effectively suppressed.

  In FIG. 6, the parallel grooves D1 and the inclined grooves D2 are formed so as to be separated from each other in the plate width direction, but the present invention is not limited to this. For example, the parallel grooves D1 and the inclined grooves D2 may be connected in the plate width direction and formed in one line.

  Further, the parallel grooves and the inclined grooves are not limited to the formation state as shown in FIG. 6, and may be formed as shown in FIG. 7, for example. Even in such a case, it is possible to suppress a decrease in the effect of iron loss improvement while preventing cracking during bending of the grain-oriented electrical steel sheet 10.

  FIG. 7 is a schematic diagram showing a modification of the groove formation state in the grain-oriented electrical steel sheet 10. In FIG. 7, in addition to the parallel grooves D1, two types of inclined grooves D2 and inclined grooves D3 are formed. The inclined grooves D2 and D3 have different inclination directions with respect to the plate width direction. In FIG. 7, the inclination angle θ of the inclined groove D2 with respect to the plate width direction is the same as the inclination angle θ of the inclined groove D3 with respect to the plate width direction. However, the present invention is not limited to this, and the inclination angle of the inclined groove D2 and the inclination angle of the inclined groove D3 may be different sizes.

  Moreover, the manufacturing method of the grain-oriented electrical steel sheet 10 is the final in order to clarify the difference of the iron loss between each part in a steel plate before the laser beam irradiation process (laser irradiation process S18 in FIG. 2). After the finish annealing step S14, it may further include an iron loss distribution measuring step which is a step of measuring the iron loss distribution in the sheet width direction of the steel sheet. In such a case, in the laser irradiation step S18, the parallel groove D1 is preferentially formed in a portion where the iron loss is relatively large in the plate width direction of the steel plate, and the iron loss is set in a portion where the iron loss is relatively small in the plate width direction of the steel plate. The inclined groove D2 is formed preferentially. Here, by forming the inclined groove D2 in the steel plate, as described above, cracking of the steel plate can be suppressed, while the effect of improving the iron loss can be reduced. Therefore, the arrangement of the parallel grooves D1 and the inclined grooves D2 in the plate width direction is determined based on the distribution of iron loss in the plate width direction of the steel plate as described above, thereby improving the iron loss improvement more effectively. Can be made.

  For example, as shown in FIG. 8, the iron loss distribution measuring step S30 is performed after the insulating film forming step S16. Thereafter, the laser irradiation step S18 is performed based on the measurement result of the iron loss distribution. In the iron loss distribution measurement step S30, portions corresponding to the respective positions in the plate width direction of the steel plate are cut out as samples, and the iron loss is measured for each sample. The iron loss distribution measuring step S30 may be performed before the insulating film forming step S16. For example, the iron loss distribution measurement step S30 may be performed after the final finish annealing step S14.

  Each sample, for example, cuts a portion of a predetermined length (for example, 1 m) on the front end side in the rolling direction of the steel plate from the steel plate, and further cuts the cut front end portion into a strip shape along the rolling direction. Can be obtained. Each sample thus obtained has a corresponding relationship with each position in the plate width direction of the steel plate. For example, each sample may correspond to a range in which a laser beam can be scanned by each laser irradiation device 106 shown in FIG. In that case, the length of each sample in the plate width direction may substantially coincide with the width in which each laser irradiation device 106 can scan the laser beam.

  Moreover, in iron loss distribution measurement process S30, an iron loss is measured by performing SST (Single Sheet Test) about each sample, for example. Specifically, the measured iron loss value is the iron loss value when the frequency is 50 Hz and the maximum magnetic flux density is 1.7 T. In the iron loss distribution measuring step S30, the iron loss distribution in the sheet width direction of the steel sheet is thus measured by measuring the iron loss for each sample as the iron loss at each position in the sheet width direction of the steel sheet. taking measurement.

  In the laser irradiation step S18 after the iron loss distribution measuring step S30, specifically, the arrangement of the parallel grooves D1 and the inclined grooves D2 in the plate width direction is determined by the ratio A (%) of the inclined grooves D2 and the plate width direction of the steel plate. Determine based on the distribution of iron loss. The ratio A (%) of the inclined groove D2 can be set based on the inclination angle θ as described above. Specifically, the ratio A (%) of the inclined groove D2 can be set as approximate expression (1). For example, when the ratio A (%) of the inclined groove D2 is 50% and 10 samples are obtained, the parallel grooves D1 are located at positions corresponding to the top five samples for iron loss in the sheet width direction of the steel sheet. And the inclined grooves D2 are arranged at positions corresponding to the lower five samples of iron loss (the upper term here means that the measured value of the iron loss is high, that is, the energy efficiency at the time of magnetization) The performance is poor, indicating that the performance is inferior, and the lower order is the opposite).

  In the laser irradiation step S18, the arrangement of the parallel grooves D1 and the inclined grooves D2 in the plate width direction is determined so that the two parallel grooves D1 are not adjacent to each other from the viewpoint of more reliably suppressing cracking of the steel plate. Also good. In such a case, the inclined groove D2 may be formed in a part of a portion where the iron loss is relatively large in the plate width direction of the steel plate. Moreover, the cutting process which shape | molds the some steel plate which has a predetermined | prescribed width | variety may be performed by cut | disconnecting the directionality electromagnetic steel plate 10 along a rolling direction as a post process of insulating-film formation process S20. In such a case, in the laser irradiation step S18, the parallel grooves D1 and the inclined grooves D2 are arranged in the plate width direction, and the grooves formed in each steel plate having a predetermined width after the cutting step are only balanced grooves D1. You may decide so that it may not become. Thereby, the crack of each steel plate after the division | segmentation by a cutting process can be suppressed more reliably. In such a case, the inclined groove D2 may be formed in a part of a portion where the iron loss is relatively large in the plate width direction of the steel plate.

<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. For example, as shown in FIG. 6, the parallel grooves D1 and the inclined grooves D2 are formed so as to be mixed in the plate width direction.

  Here, laser irradiation apparatuses 106A and 106B shown in FIG. 4 were used as the laser irradiation apparatuses. 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 in a present Example, it shows in FIGS. 9-12 by manufacturing the directional electromagnetic steel plate 10 from which the inclination angle of an inclination groove | channel, and the ratio of an inclination groove differ, and measuring the manufactured directional electromagnetic steel plate 10 The measurement result was obtained.

  FIG. 9 is a graph showing an example of the relationship between the groove inclination angle and the average number of repeated bending of the steel sheet. The horizontal axis of the graph shows the inclination angle of the groove, and the vertical axis of the graph shows the average number of repeated bending of the steel sheet. Here, the average number of repeated bending means the average number of times that the steel sheet can be repeatedly bent without cracking when the steel sheet is subjected to a bending test. As can be seen from the graph of FIG. 9, when the inclination angle of the groove is 0 degree (that is, when the groove is parallel to the plate width direction as shown in FIG. 5), the average number of repeated bendings is 0.5. The result was that the steel plate was easily broken. On the other hand, as the inclination angle of the groove increases, the average number of repeated bending tends to increase.

  As can be seen from the graph of FIG. 9, when the groove inclination angle is 15 degrees or more, the degree of increase in the average number of repeated bendings is larger than when the groove inclination angle is less than 15 degrees. If the average number of repeated bendings is 3 times or more, it is possible to effectively suppress the cracking of the steel sheet during the production of the wound iron core, so the groove inclination angle is preferably 15 degrees or more. However, it is more desirable that the inclination angle of the groove is 20 degrees or more. In such a case, the average number of repeated bending is 7 times, and the cracking of the steel sheet can be more reliably prevented.

  By the way, when the grooves are formed in a direction intersecting the plate width direction, the generation of magnetic poles is reduced, and the effect of improving the iron loss is reduced.

  FIG. 10 is a graph showing an example of the relationship between the groove inclination angle and the iron loss improvement rate. The horizontal axis of the graph indicates the groove inclination angle, and the vertical axis of the graph indicates the iron loss improvement rate. As can be seen from the graph of FIG. 10, the iron loss improvement rate tends to decrease as the groove inclination angle increases. In particular, if the groove inclination angle is greater than 20 degrees, the iron loss improvement rate is greatly reduced. Therefore, the groove inclination angle is desirably 20 degrees or less.

  Therefore, as described above, in order to suppress the reduction in the effect of iron loss improvement while preventing cracking during bending of the grain-oriented electrical steel sheet 10, not only the inclined grooves are formed, but in the plate width direction. It is desirable to form the parallel grooves D1 and the inclined grooves D2 in FIG.

  FIG. 11 is a graph showing an example of the relationship between the ratio of the inclined grooves and the average number of repeated bendings. The horizontal axis of the graph indicates the ratio of the inclined grooves, and the vertical axis of the graph indicates the average number of repeated bending. The inclination angle of the inclined groove used in the measurement of FIG. 11 is 20 degrees. As can be seen from the graph of FIG. 11, in order to exceed the average number of repeated bendings that can effectively suppress cracks in the steel sheet, the ratio of the inclined grooves with an inclination angle of 20 degrees should be about 50% or more. Is desirable. That is, it is necessary to mix the parallel grooves D1 and the inclined grooves D2 in the plate width direction by the same ratio.

  In FIG. 11, an inclined groove having an inclination angle of 20 degrees has been described. However, in the case of other inclination angles, in order for the average number of repeated bendings to be three or more, the ratio of the inclined grooves as shown in FIG. There is a need to.

FIG. 12 is a graph showing an example of the relationship between the inclination angle of the inclined grooves and the ratio of the inclined grooves. The horizontal axis of the graph indicates the inclination angle of the inclined groove, and the vertical axis of the graph indicates the ratio of the inclined groove. As can be seen from the graph, the ratio of the inclined grooves tends to decrease as the inclination angle increases. From the measurement result of FIG. 12, the following approximate expression (1) showing the relationship between the inclination angle θ of the inclined groove and the ratio A is obtained.
Ratio A = −3.22 × tilt angle θ + 110 (1)

  In the measurement in which the measurement results are shown in FIG. 9, the grooves are formed in a single line connected in the plate width direction for each inclination angle. On the other hand, in the measurement whose measurement results are shown in FIGS. 11 and 12, the parallel grooves D1 and the inclined grooves D are formed intermittently along the plate width direction so as to be separated from each other. Even when the inclination angle of the groove and the ratio of the inclined groove coincide, when the groove is formed in a single line connected in the plate width direction, the groove is intermittently formed along the plate width direction. Sometimes the average number of repeated bends can be different. Here, the measurement whose measurement result is shown in FIG. 9 corresponds to the case where the ratio of the inclined grooves is 100%. For example, according to FIG. 9 which is such a measurement result, the average number of repeated bendings when the groove inclination angle is 5 degrees or 10 degrees is less than 3. On the other hand, according to FIG. 12, the average number of repeated bendings when the inclination angle of the grooves is 5 degrees or 10 degrees can exceed 3 times when the ratio of the inclined grooves is a predetermined value or more. In this way, when the groove is formed intermittently along the plate width direction, the average number of repeated bendings is increased compared to when the groove is formed in a single line connected in the plate width direction. There is.

<Summary>
As described above, in the grain-oriented electrical steel sheet 10 according to this embodiment, as shown in FIG. 6, the extending direction is parallel to the sheet width direction of the steel sheet, and the extending direction is the sheet width. The inclined grooves D2 formed so as to intersect the direction are formed so as to be mixed in the plate width direction.

  By forming the inclined groove D2 in which the groove extending direction intersects the sheet width direction perpendicular to the bending direction at the time of bending the steel sheet, it is possible to suppress the occurrence of cracks during bending of the grain-oriented electrical steel sheet. There is a risk that the effect of loss improvement will be reduced. On the other hand, the parallel groove D1 is more advantageous in improving the iron loss than the inclined groove D2. Therefore, by forming the parallel grooves D1 and the inclined grooves D2 together in the plate width direction, it is possible to prevent a reduction in the iron loss improvement effect while preventing cracking during the bending of the grain-oriented electrical steel sheet 10. It becomes.

  In particular, in the present embodiment, the groove is formed deep so that the depth of the groove is 0.2 or more times the width of the groove. If the groove is deep, cracks are likely to occur during bending, but as described above, the parallel grooves D1 and the inclined grooves D2 are formed so as to be mixed in the plate width direction, so that The effect of suppressing the occurrence of cracks is more effectively exhibited.

  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 100 Laser processing apparatus 102 Laser oscillator 104 Transmission fiber 106A, 106B Laser irradiation apparatus D1 Parallel groove D2, D3 Inclined groove

Claims (7)

A method for producing a grain-oriented electrical steel sheet comprising a step of irradiating a laser beam in a direction intersecting a conveying direction of a steel sheet and forming grooves at a predetermined interval in the conveying direction,
A first groove formed so that the extending direction is parallel to the plate width direction of the steel sheet and a second groove formed so that the extending direction intersects the plate width direction are mixed in the plate width direction. A method for producing a grain-oriented electrical steel sheet, characterized in that it is formed as described above. In the manufacturing method of the grain-oriented electrical steel sheet according to claim 1,
A first irradiation unit and a second irradiation unit for irradiating a laser beam are arranged along the plate width direction,
The method for producing a grain-oriented electrical steel sheet, wherein the first groove is formed by the first irradiation unit, and the second groove is formed by the second irradiation unit. In the manufacturing method of the grain-oriented electrical steel sheet according to claim 1 or 2,
The method for producing a grain-oriented electrical steel sheet, wherein the first groove and the second groove are alternately formed in the plate width direction. In the manufacturing method of the grain-oriented electrical steel sheet according to any one of claims 1 to 3,
The ratio A of the second groove of the first groove and the second groove satisfies the following formula (1) when the angle formed between the second groove and the plate width direction is an angle θ. A method for producing a grain-oriented electrical steel sheet, comprising:
Ratio A = −3.22 × angle θ + 110 (1) In the manufacturing method of the grain-oriented electrical steel sheet according to any one of claims 1 to 4,
Before the step of irradiating the laser beam, further comprising the step of measuring the distribution of iron loss in the plate width direction of the steel plate,
Preferentially forming the first groove in a portion where the iron loss is relatively large in the plate width direction, and preferentially forming the second groove in a portion where the iron loss is relatively small in the plate width direction;
A method for producing grain-oriented electrical steel sheets. In the manufacturing method of the grain-oriented electrical steel sheet according to any one of claims 1 to 5,
The method for producing a grain-oriented electrical steel sheet, wherein the depth of the groove is 0.2 times or more the width of the groove. A grain-oriented electrical steel sheet having grooves formed at predetermined intervals in the transport direction by being irradiated with a laser beam in a direction intersecting the transport direction of the steel sheet,
A first groove formed so that the extending direction is parallel to the plate width direction of the steel sheet and a second groove formed so that the extending direction intersects the plate width direction are mixed in the plate width direction. A grain-oriented electrical steel sheet characterized by being formed as described above.

Images