Grain-oriented electrical steel sheet and method for producing same

Abstract

The grain-oriented electrical steel sheet is provided with a plurality of magnetic domain control processing lines extending in a direction intersecting the rolling direction on the surface, a square evaluation region having one side length of 50 mm and the other side parallel to the rolling direction is set on the surface, and a plurality of magnetic domain control processing lines extending in the direction intersecting the rolling direction are set inside the evaluation region. When virtual lines parallel to the rolling direction and having a length of 50 mm are set at 5 mm intervals in a direction perpendicular to the rolling direction, in at least one of the virtual lines, the maximum value of the interval in the rolling direction between adjacent intersections among a plurality of intersections between the virtual line and the plurality of magnetic domain control processing lines exceeds 20 mm, and the maximum value of the interval in the rolling direction between adjacent intersections among the plurality of intersections among the plurality of magnetic domain control processing lines exceeds 20 mm. And the average magnetic domain width measured along the imaginary line is 600 [mu] m or less.

Description

Technical Field

[0001] This invention relates to oriented electromagnetic steel sheets and their manufacturing methods.

[0002] This application claims priority based on Japanese Patent Application No. 2023-166097, filed in Japan on September 27, 2023, the contents of which are incorporated herein by reference. Background Technology

[0003] Oriented electromagnetic steel sheets contain less than 7% by mass of Si and have secondary recrystallized grains along the easily magnetized axis. <001> {110} oriented in the rolling direction <001> Oriented (Goss orientation) steel sheets with a secondary recrystallization texture. Oriented electromagnetic steel sheets are mainly used as the cores of power transformers. For oriented electromagnetic steel sheets, it is required to reduce energy loss (iron loss).

[0004] To reduce iron loss, techniques for narrowing the domain width of oriented electromagnetic steel sheets (domain subdivision technology based on domain control processing) are previously known. Domain width can be narrowed by inducing thermal strain by irradiating the surface of the oriented electromagnetic steel sheet with a laser or electron beam in a direction intersecting the rolling direction. Alternatively, domain width can also be narrowed by forming grooves on the surface of the oriented electromagnetic steel sheet in a direction intersecting the rolling direction. Methods for forming these grooves include laser or electron beam irradiation, mechanical processing methods such as gear machining, and chemical processing methods such as etching.

[0005] In recent years, in order to provide oriented electromagnetic steel sheets with good iron loss characteristics, various improvement technologies related to magnetic domain subdivision have been proposed (for example, see Patent Documents 1 to 3).

[0006] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2012-57219 Patent Document 2: Japanese Patent Application Publication No. 2012-12664 Patent Document 3: Japanese Patent Application Publication No. 2012-57218 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] When magnetic domain control is applied to oriented electromagnetic steel sheets, the magnetostrictive properties of the sheets change due to the closed magnetic domains. This deteriorates the noise characteristics of the oriented electromagnetic steel sheets. Noise characteristics refer to the level of noise generated by electrical products (such as transformers and motors) manufactured using oriented electromagnetic steel sheets as materials. Magnetostriction refers to the phenomenon of slight deformation of the shape when a strongly magnetic material is magnetized. When oriented electromagnetic steel sheets are excited using alternating current, the magnitude of magnetostriction changes with the intensity of magnetization, thereby generating vibration. The magnitude of this magnetostriction is 10. -6 Although the magnetostriction of the magnetostrictive field is very small, it causes the iron core to vibrate, which propagates to external structures such as transformer tanks and becomes noise. In other words, while magnetic domain control is effective in reducing iron losses in oriented electromagnetic steel sheets, it conversely worsens the noise characteristics of these sheets.

[0009] In recent years, there has been a growing demand for both low iron loss and low noise in oriented electromagnetic steel sheets. However, to date, no magnetic domain subdivision technology has been proposed that can fully achieve both low noise and low iron loss.

[0010] The purpose of this disclosure is to provide an orientation-oriented electromagnetic steel sheet with low iron loss (low iron loss) and low noise when manufactured into motor products (excellent noise characteristics) and a method for manufacturing the same.

[0011] means for solving problems

[0012] The inventors have studied methods for reducing iron loss and suppressing the deterioration of noise characteristics.

[0013] The results showed that by expanding the interval of the magnetic domain control process in at least a portion of specific regions, it is possible to obtain orientation-oriented electromagnetic steel sheets with low iron loss and excellent noise characteristics.

[0014] This disclosure is made in view of the foregoing insights. The main points of this disclosure are as follows.

[0015] [1] In one embodiment of the present disclosure, an orientation-oriented electromagnetic steel sheet has multiple domain control processing lines extending on its surface in a direction intersecting the rolling direction. An evaluation area is set on the surface, with one side having a length of 50 mm and the other side being parallel to the rolling direction. Furthermore, inside the evaluation area, imaginary lines with a length of 50 mm are set at 5 mm intervals along a direction perpendicular to the rolling direction. In at least one of the imaginary lines, the maximum value of the interval between adjacent intersections of the imaginary line and the multiple domain control processing lines in the rolling direction exceeds 20 mm, and the average value of the domain width measured along the imaginary line is 600 μm or less.

[0016] [2] According to the orientation electromagnetic steel sheet described in [1], the average value of the magnetic domain width measured along the imaginary line may be less than 500 μm.

[0017] [3] According to the orientation electromagnetic steel sheet described in [1], it is also possible that, in each of the imaginary lines in two or more of the rolling directions, the average value of the magnetic domain width measured along the imaginary lines is 600 μm or less.

[0018] [4] The oriented electromagnetic steel sheet according to any one of [1] to [3] may also be such that, in each of the imaginary lines in two or more of the rolling directions, the average value of the magnetic domain width measured along the imaginary lines is 500 μm or less.

[0019] [5] The oriented electromagnetic steel sheet according to any one of [1] to [4] may also have a maximum value of the interval in the rolling direction exceeding 30 mm.

[0020] [6] Another aspect of the present disclosure has an orientation-oriented electromagnetic steel sheet having multiple domain control processing lines extending on the surface in a direction intersecting the rolling direction. An evaluation area is set on the surface with one side having a length of 50 mm and the other side being parallel to the rolling direction. Furthermore, inside the evaluation area, imaginary lines with a length of 50 mm and parallel to the rolling direction are set at 5 mm intervals along a direction perpendicular to the rolling direction. In at least one of the imaginary lines, the maximum value of the interval between adjacent intersections of the imaginary line and the multiple domain control processing lines in the rolling direction exceeds 20 mm, and the maximum value of the domain width measured along the imaginary line is less than 1200 μm.

[0021] [7] According to the orientation electromagnetic steel sheet described in [6], the maximum value of the magnetic domain width measured along the imaginary line may be less than 800 μm.

[0022] [8] According to the orientation electromagnetic steel sheet described in [6], it is also possible that, in each of the imaginary lines in two or more of the rolling directions where the maximum value of the interval exceeds 20 mm, the maximum value of the magnetic domain width measured along the imaginary line is 1200 μm or less.

[0023] [9] The oriented electromagnetic steel sheet according to any one of [6] to [8] may also be such that, in each of the imaginary lines in two or more of the rolling directions where the maximum value of the interval exceeds 20 mm, the maximum value of the magnetic domain width measured along the imaginary line is 800 μm or less.

[0024]

[10] The oriented electromagnetic steel sheet according to any one of [6] to [9] may also have a maximum value of the interval in the rolling direction exceeding 30 mm.

[0025]

[11] The oriented electromagnetic steel plate according to any one of [1] to

[10] may also be a groove, wherein the multiple magnetic domain control processing lines are grooves.

[0026]

[12] The oriented electromagnetic steel sheet according to any one of [1] to

[10] may also be thermal strain, wherein the multiple magnetic domain control processing lines are thermal strain.

[0027]

[13] Another aspect of the present disclosure is a method for manufacturing an orientation-oriented electromagnetic steel sheet, as described in any one of [1] to [9], comprising: a magnetic domain image acquisition step, acquiring a magnetic domain image of the surface of the orientation-oriented electromagnetic steel sheet; a region-specification step, based on the magnetic domain image obtained in the magnetic domain image acquisition step, specifying a region in the orientation-oriented electromagnetic steel sheet where the magnetic domain width exceeds 500 μm; and a magnetic domain control processing line formation step, forming a magnetic domain control processing line on the surface of the orientation-oriented electromagnetic steel sheet after the region-specification step; wherein, in the magnetic domain control processing line formation step, the magnetic domain control processing line is formed in the region where the magnetic domain width exceeds 500 μm.

[0028]

[14] The manufacturing method of the oriented electromagnetic steel sheet according to

[13] may also be that the magnetic domain control processing line is formed by irradiation with a laser or electron beam in the magnetic domain control processing line forming process.

[0029] Invention Effects

[0030] According to the above-described solution of this disclosure, it is possible to provide an orientation-oriented electromagnetic steel sheet with low iron loss (low iron loss) and low noise when manufactured into motor products (excellent noise characteristics) and a method for manufacturing the same. Attached Figure Description

[0031] Figure 1A This is a schematic diagram illustrating an example of an orientation-oriented electromagnetic steel sheet according to this embodiment.

[0032] Figure 1B This is a schematic diagram illustrating an example of an orientation-oriented electromagnetic steel sheet according to this embodiment.

[0033] Figure 1C This is a schematic diagram illustrating an example of an orientation-oriented electromagnetic steel sheet according to this embodiment.

[0034] Figure 2 This is a graph showing the relationship between the domain width before and after laser irradiation.

[0035] Figure 3A This is a diagram illustrating an example of the distribution of magnetic domain widths in an orientation-type electromagnetic steel sheet before magnetic domain subdivision processing.

[0036] Figure 3B This is a diagram illustrating an example of the distribution of magnetic domain widths in an orientation-oriented electromagnetic steel sheet after magnetic domain subdivision processing.

[0037] Figure 3C This is a diagram showing an example of a magnetic domain image acquired by an image acquisition device.

[0038] Figure 3D It is shown schematically. Figure 3C The image.

[0039] Figure 4 This is a block diagram illustrating an example of the hardware configuration of an image acquisition device.

[0040] Figure 5 This is a block diagram illustrating an example of the hardware configuration of a parsing device.

[0041] Figure 6 This is a schematic diagram illustrating an example of the configuration of a laser irradiation device.

[0042] Figure 7 This is a schematic diagram illustrating a method for cutting out multiple partial regions from a magnetic domain image of a oriented electromagnetic steel sheet.

[0043] Figure 8 This is an example of obtaining multiple partial Fourier images by performing two-dimensional Fourier transforms on multiple partial regions cut out from the magnetic domain image of the oriented electromagnetic steel plate. Detailed Implementation

[0044] An orientation-oriented electromagnetic steel sheet (the orientation-oriented electromagnetic steel sheet of this embodiment) and its manufacturing method according to one embodiment of the present disclosure will be described.

[0045] like Figure 1AAs shown, the orientation-oriented electromagnetic steel sheet 1 of this embodiment has multiple domain control processing lines 11 extending in a direction intersecting the rolling direction RD on its surface. An evaluation area with a length of 50 mm on one side and parallel to the rolling direction RD on the other side is set on the surface. Furthermore, in the evaluation area, when imaginary lines VL with a length of 50 mm and parallel to the rolling direction RD are set at 5 mm intervals along a direction perpendicular to the rolling direction RD, in at least one (preferably two or more) imaginary lines VL, among the multiple intersection points VP of the imaginary line VL and the multiple domain control processing lines 11, the maximum value (dmax) of the interval (d1~d7) between adjacent intersection points in the rolling direction RD is greater than 20 mm (preferably greater than 30 mm), and the average value of the domain width measured along the imaginary line VL is 600 μm or less, or the maximum value of the domain width is 1200 μm or less.

[0046] As described below, the orientation electromagnetic steel sheet of this embodiment may have a magnesium olivine coating and / or an insulating coating on the surface of the steel sheet that serves as the base material steel sheet.

[0047] The following will explain each point separately. However, when the oriented electromagnetic steel sheet has a base steel sheet, a forsterite coating, and / or an insulating coating, the following specifications regarding chemical composition, domain control treatment lines, intersection spacing, and domain width pertain to the base steel sheet. However, the specifications regarding sheet thickness pertain to the entire oriented electromagnetic steel sheet, including the base steel sheet, the forsterite coating, and / or the insulating coating.

[0048] Oriented magnetic steel sheet

[0049] (Chemical composition)

[0050] The chemical composition of the orientation-oriented electromagnetic steel sheet 1 is not limited, as long as it is the same as that of the known orientation-oriented electromagnetic steel sheet 1. For example, the chemical composition of oriented electromagnetic steel sheet 1, by mass%, may contain: Si: 2.50~7.00%, Mn: 0~1.00%, C: 0~0.085%, acid-soluble Al: 0~0.065%, N: 0~0.012%, Cr: 0~0.300%, Cu: 0~0.400%, P: 0~0.500%, Sn: 0~0.300%, Sb: 0~0.300%, Ni: 0~1.000%, S: 0~0.015%, Se: 0~0.015%, Bi: 0~0.020%, Nb: 0~0.030%, V: 0~0.030%, Mo: 0~0.030%, Ta: 0~0.030%, W: 0~0.030%, B: 0~0.080%, Ti: 0~0.015%. The chemical composition balance includes Fe and impurities.

[0051] The chemical composition of the orientation-oriented electromagnetic steel sheet 1 can be determined using general analytical methods for steel. For example, the chemical composition can be determined using ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectrometry). Specifically, a test piece is taken from the center of the sample along its thickness direction, and the chemical composition of the orientation-oriented electromagnetic steel sheet 1 can be determined using a Shimadzu ICPS-8100 or similar measuring device under conditions based on a pre-prepared standard curve. The contents of C and S, which are difficult to determine in ICP-AES, can be determined using the combustion-infrared absorption method. The N content can be determined using the inactive gas melting-thermal conductivity method.

[0052] When a magnesium olivine coating and / or an insulating coating are formed on the orientation-oriented electromagnetic steel sheet 1, the chemical composition of the orientation-oriented electromagnetic steel sheet 1 (i.e., the chemical composition of the base steel sheet) can be analyzed after removing the magnesium olivine coating and / or the insulating coating from the orientation-oriented electromagnetic steel sheet 1.

[0053] Insulating coatings can be removed, for example, by immersing the sample in a sodium hydroxide solution, followed by immersion in dilute sulfuric acid and nitric acid. The temperature and concentration of the sodium hydroxide, dilute sulfuric acid, and nitric acid solutions, as well as the immersion time, should be appropriately adjusted to prevent excessive dissolution of the iron-based components of the sample. An example of the conditions for removing the insulating coating is as follows: First, immerse the sample in a 20% sodium hydroxide solution at 80°C for 15 minutes. Then, allow the sample to dry. Next, immerse the sample in a 10% dilute sulfuric acid solution at 80°C for 4 minutes. Then, remove any residue adhering to the sample surface with a rag or similar material. Finally, immerse the sample in a 10% nitric acid solution at room temperature for approximately 10 seconds while stirring.

[0054] For example, forsterite coatings can be removed by immersing the sample in sulfuric acid followed by nitric acid. Appropriate adjustments to the temperature and concentration of the sulfuric and nitric acids, as well as the immersion time, are necessary to prevent excessive dissolution of the iron-based components in the sample. An example of the conditions for removing forsterite coatings is as follows: First, immerse the sample in 10% sulfuric acid at 80°C for 3 minutes. Then, wash the surface of the sample with water using a rag or similar material to remove any adhering residue. Next, allow the sample to dry. Then, immerse the sample in 10% nitric acid at room temperature for approximately 5 seconds while stirring.

[0055] The thickness of the oriented electromagnetic steel sheet 1 is not limited, but is preferably 0.15 mm to 0.30 mm. By setting it to 0.30 mm or less, classical eddy current losses can be suppressed, further improving iron loss. On the other hand, by making the sheet thickness 0.15 mm or more, rolling efficiency can be improved, thus increasing productivity.

[0056] (Magnetic domain control processing line 11)

[0057] Multiple magnetic domain control lines 11 disposed on the surface of the oriented electromagnetic steel sheet 1 serve to subdivide 180° magnetic domains. By subdividing the magnetic domains, the iron loss of the oriented electromagnetic steel sheet 1 can be reduced. A magnetic domain refers to a collection of magnetic dipoles existing inside a strongly magnetic material, with the magnetic moment aligned along a small region. A 180° magnetic domain refers to a magnetization direction aligned with the crystal structure. <100> A domain is oriented and sandwiched between two 180° domain walls that are approximately parallel to the rolling direction RD. The distance between adjacent domain walls of a 180° domain (domain wall spacing) is called the width of the 180° domain. Hereinafter, unless otherwise specified, the width of the 180° domain will be simply referred to as the "domain width".

[0058] The extension direction of the domain control processing line 11 is not particularly limited as long as it intersects the rolling direction (as long as it is not parallel to the rolling direction). The domain control processing line 11 and the rolling direction RD can also be approximately right-angled (approximately parallel to the right-angled rolling direction TD). That is, the angle between the domain control processing line 11 and the right-angled rolling direction TD can also be substantially 0°. On the other hand, as... Figure 1A As illustrated, the angle between the domain control processing line 11 and the rolling right-angle direction TD can also exceed 0°. For example, the angle between the domain control processing line 11 and the rolling right-angle direction TD can be set to any value within the range of 0 to 45°. The angle between the domain control processing line 11 and the rolling right-angle direction TD can also be set to 1° or more, 3° or more, or 5° or more. The angle between the domain control processing line 11 and the rolling right-angle direction TD can also be set to 40° or less, 35° or less, or 30° or less.

[0059] like Figure 1A As illustrated, the angles formed by all the domain control processing lines 11 and the rolling right-angle direction TD can be the same. That is, all the domain control processing lines 11 can extend parallel to each other. On the other hand, the angles formed by the domain control processing lines 11 and the rolling right-angle direction TD can be uneven. That is, some or all of the multiple domain control processing lines 11 can extend non-parallel to each other. The average value of the angles formed by the domain control processing lines 11 and the rolling right-angle direction TD can also be set to 1° or more, 3° or more, or 5° or more. The average value of the angles formed by the domain control processing lines 11 and the rolling right-angle direction TD can also be set to 40° or less, 35° or less, or 30° or less. The average value of the angle is calculated by measuring the angles formed by one domain control processing line and the rolling right-angle direction TD at multiple locations, or by measuring the angles formed by multiple domain control processing lines and the rolling right-angle direction TD at one or more locations, and then calculating the average value.

[0060] Additionally, if dmax (the maximum value of the interval between adjacent intersections in the rolling direction among the multiple intersections of the imaginary line and the multiple magnetic domain control processing lines) exceeds 20 mm, then... Figure 1B As shown, even if the domain control processing line 11 is not interrupted in the middle (i.e., all domain control processing lines can be formed in the entire width direction of the steel plate), the domain control processing line 11 is as follows: Figure 1C As shown, it can also include curved parts (i.e., it can also be composed of more than just straight lines).

[0061] The type of magnetic domain control processing line 11 is not particularly limited, but preferred examples are thermal strain and / or grooves. Thermal strain can be formed, for example, by means of laser irradiation, electron beam irradiation, and ion implantation. Grooves can be formed, for example, by means of laser irradiation, electron beam irradiation, machining, etching, etc.

[0062] Thermal strain disappears through stress-relief annealing or heat treatment based thereon. Therefore, when the orientation-oriented electromagnetic steel sheet 1 is heat-treated, the domain control processing line 11 is preferably provided as a groove. On the other hand, since thermal strain can be easily formed, the domain control processing line 11 is preferably provided as thermal strain when simplification of the manufacturing process is required. The orientation-oriented electromagnetic steel sheet 1 may also have both thermal strain and groove.

[0063] When the magnetic domain control processing line 11 is a slot, the magnetic domain control processing line 11 can be identified by visual inspection. When the oriented electromagnetic steel sheet 1 has an insulating film, the magnetic domain control processing line 11 can be visually identified by removing the insulating film using a known stripping agent.

[0064] When the domain control processing line 11 is subjected to thermal strain, it may sometimes be impossible to identify visually. In such cases, for example, using... Figure 4 The image acquisition device 30, configured as illustrated, captures magnetic domain images. By observing the captured magnetic domain images, the location of thermal strain can be determined. During capture, a DC magnetic field is applied along the normal direction ND of the rolled surface of the oriented electromagnetic steel sheet 1 as needed, while capturing the magnetic domain images.

[0065] (The interval between the intersections of the imaginary line parallel to the rolling direction and the magnetic domain control processing line)

[0066] (Magnetic domain width)

[0067] As described above, the domain control processing lines 11 provided on the surface of the oriented electromagnetic steel sheet 1 have the function of subdividing the 180° magnetic domains. Furthermore, the smaller the spacing between the domain control processing lines, the better the effect of improving iron loss. Therefore, in typical domain control processing, the spacing between each domain control processing line is formed to be no more than 20 mm.

[0068] In contrast, in the orientation-oriented electromagnetic steel sheet of this embodiment, a square evaluation area with one side length of 50 mm and one side parallel to the rolling direction RD is set on the surface. Inside the evaluation area, imaginary lines VL with a length of 50 mm and parallel to the rolling direction RD are set at 5 mm intervals along a direction perpendicular to the rolling direction. In at least one imaginary line VL, among the multiple intersection points VP of the imaginary line VL and the multiple domain control processing lines 11, the maximum value of the interval between adjacent intersection points in the rolling direction RD exceeds 20 mm. That is, in at least a portion, the interval in the rolling direction of the domain control processing lines exceeds 20 mm. Figure 1A The example shown depicts the state of drawing only one imaginary line VL. When multiple imaginary lines VL are set, it is possible to... Figure 1A The required number of other imaginary lines are set parallel to the imaginary line VL.

[0069] Furthermore, in the oriented electromagnetic steel sheet of this embodiment, in the imaginary line VL where the maximum value of the interval in the rolling direction RD exceeds 20 mm, at least one of the following listed requirements is satisfied. (1) The average value of the domain width measured along the imaginary line VL is less than 600 μm. (2) The maximum value of the magnetic domain width measured along the imaginary line VL is less than 1200 μm.

[0070] The above-mentioned requirements (1) and (2) can also be satisfied by both. That is, the average value of the domain width measured along the imaginary line VL can be less than 600 μm, and the maximum value can be less than 1200 μm.

[0071] As mentioned above, while the magnetic domain control process effectively reduces iron loss in oriented electromagnetic steel sheets, it also deteriorates the noise characteristics of these sheets. Therefore, by reducing the density of the magnetic domain control processing lines, the deterioration of noise characteristics can be suppressed. In other words, a good balance can be achieved between low noise and low iron loss.

[0072] The maximum value of the interval between intersections exceeding 20 mm refers to the area in the steel plate where the interval in the rolling direction of the magnetic domain control processing line exceeds 20 mm, which is more preferable from the point of view of low noise.

[0073] From a low-noise perspective, it is preferable that the maximum value of the interval between adjacent intersections VP of the imaginary line VL and the multiple magnetic domain control processing lines 11 in the rolling direction RD exceeds 30 mm. If the magnetic domain control processing unique to this embodiment is applied to a steel sheet with a coarse grain size, the maximum value of the interval in the rolling direction RD tends to increase because the steel sheet has a coarse grain size.

[0074] In the orientation-oriented electromagnetic steel sheet of this embodiment, among the imaginary lines VL with a maximum spacing of more than 30 mm in the rolling direction RD, it is more preferable to satisfy at least one of the following listed requirements. (1) The average value of the domain width measured along the imaginary line VL is less than 600 μm. (2) The maximum value of the magnetic domain width measured along the imaginary line VL is less than 1200 μm.

[0075] The inventors further investigated and analyzed the changes in magnetic domains before and after domain control in oriented electromagnetic steel sheets. The results clearly showed that there were regions where the domain width became thinner due to domain control and regions where it remained almost unchanged. In other words, they found that the domain subdivision effect differed when using domain control processing based on the original domain width. More specifically, in regions with narrow domain widths, the domain subdivision effect of domain control processing was difficult to observe.

[0076] Generally, when aiming to increase the orientation density towards the Goss orientation to improve magnetic flux density, there is a tendency for the grain size to increase due to the manufacturing process. While steel sheets with such coarse grain sizes exhibit excellent magnetic flux density, the excessively large grains tend to result in high iron losses without domain control treatment. Therefore, domain control is practically necessary. However, while conventional domain control treatments are effective in reducing iron losses in orientation-oriented electromagnetic steel sheets, they can conversely degrade the noise characteristics of these sheets.

[0077] Based on the above insights, it is evident that prioritizing domain control processing in regions with wide domain widths is extremely effective in achieving both low iron loss and low noise. Domain control processing in regions with wide domain widths can reduce iron loss. It is believed that domain control processing lines formed in regions with narrow domain widths lead to a deterioration in noise characteristics caused by closed domains; therefore, minimizing domain control processing in regions with narrow domain widths can prevent this deterioration in noise characteristics.

[0078] Therefore, in order to minimize the deterioration of noise characteristics while simultaneously reducing iron losses, domain control processing is primarily performed in regions with wide domain widths and high domain subdivision. Preferably, domain control processing is performed only in regions with wide domain widths, but performing it in regions with narrow domain widths is permissible if the proportion is small, as the deterioration of noise characteristics is also small. Furthermore, for regions with wide domain widths, it is preferable to perform domain control processing on the entire region; however, regions without domain control processing may be included within the range sufficient to achieve a significant reduction in iron losses.

[0079] The inventors have conducted further research on the magnetic domain subdivision effect, such as... Figure 2As shown, in regions where the domain width is approximately 500 μm or less, the domain width is approximately the same before and after the domain control treatment. That is, it is considered that in regions where the domain width is approximately 500 μm or less, the effect of domain subdivision brought about by domain control is almost negligible. Therefore, in the orientation-oriented electromagnetic steel sheet of this embodiment, in order to reduce the density of the domain control treatment lines and sufficiently obtain the effect of reducing iron loss, domain control is intentionally not performed in such regions where the domain width is 500 μm or less, and domain control treatment lines are mainly formed in regions where the domain width exceeds 500 μm. As a result, in the orientation-oriented electromagnetic steel sheet of this embodiment, in the imaginary lines VL where the maximum value of the interval in the rolling direction RD exceeds 20 mm, the average value of the domain width measured along the imaginary lines is 600 μm or less, or the maximum value is 1200 μm or less. That is, in the orientation-oriented electromagnetic steel sheet 1 that satisfies at least one of requirements (1) and (2), the domain width is a small value throughout the entire imaginary line VL. Therefore, it is possible to achieve a good balance between low noise and low iron loss.

[0080] In the orientation-oriented electromagnetic steel sheet of this embodiment, it is preferable that among two or more imaginary lines VL, the maximum value of the interval between adjacent intersections VP in the rolling direction exceeds 20 mm (more preferably exceeds 30 mm), and at least one of the following listed requirements is satisfied. (1) The average value of the domain width measured along each imaginary line VL is less than 600 μm. (2) The maximum value of the magnetic domain width measured along each imaginary line VL is less than 1200 μm.

[0081] The above-mentioned requirements (1) and (2) can also be satisfied by both. That is, the average value of the domain width measured along the imaginary line VL can be less than 600 μm, and the maximum value can be less than 1200 μm.

[0082] Among multiple imaginary lines, the region where the maximum interval between intersections exceeds 20 mm refers to the region where the interval between the rolling directions of the magnetic domain control processing lines at multiple locations on the steel plate exceeds 20 mm, which is more preferable from the point of view of low noise.

[0083] The average value of the aforementioned domain width is further preferably 500 μm or less, 450 μm or less, 400 μm or less, 380 μm or less, 350 μm or less, or 300 μm or less. Furthermore, the maximum value of the domain width is further preferably 1000 μm or less, 800 μm or less, 600 μm or less, 500 μm or less, 450 μm or less, or 400 μm or less.

[0084] The interval of the rolling direction at the intersection of the imaginary line and the multiple domain control processing lines, the average value of the domain width measured along the imaginary line, and the maximum value are obtained by the following method.

[0085] For example, rectangular specimens with side lengths of 100 mm (or more) can be cut from the oriented electromagnetic steel sheet 1 for measurement. When the oriented electromagnetic steel sheet 1 is a roll, the specimen can be taken from any part of the roll. Alternatively, when the oriented electromagnetic steel sheet 1 is a component assembled into transformers, motors, or other motor products, the specimen can be taken from any part of the component. If the component is small, and one side of the specimen is 50 mm or more, the length of one side of the specimen can be set to be less than 100 mm. In this case, to minimize the influence of mechanical strain on the specimen, it is preferable to take the specimen using methods such as wire cutting.

[0086] For this sample, magnetic domain images are obtained using an image acquisition device that includes a light source, a magneto-optical sensor (MO sensor), an image sensor, and a signal processing unit.

[0087] In this magnetic domain image, an evaluation area is set as a square with one side length of 50 mm and one side parallel to the rolling direction. Then, inside the evaluation area, an imaginary line VL with a length of 50 mm and parallel to the rolling direction is set at 5 mm intervals along a direction perpendicular to the rolling direction.

[0088] The interval between the intersection points of the imaginary line VL and the multiple magnetic domain control processing lines 11 is measured, and the maximum value is taken as the maximum value of the interval between adjacent intersection points in the rolling direction.

[0089] The average and maximum domain widths measured along the imaginary line VL are determined by multiple sub-imaginary lines that are perpendicular to the plate surface (thickness direction) and intersect the imaginary line VL. The sub-imaginary lines are 5 mm long and spaced 2 mm apart along the rolling direction. Each sub-imaginary line is positioned to intersect the imaginary line VL at its center. The number of domains contained in each sub-imaginary line is measured, and the value obtained by dividing the length of the sub-imaginary line by the number of domains it contains is considered the domain width on the sub-imaginary line. The average domain width on the sub-imaginary lines is set as the average domain width measured along the imaginary line, and the maximum domain width on the sub-imaginary lines is set as the maximum domain width measured along the imaginary line.

[0090] That is, in this embodiment, "along the imaginary line VL" means that there are secondary imaginary lines at equal intervals on the imaginary line at the center.

[0091] There are no limitations on the location where the evaluation region and the imaginary line VL are set. The evaluation region and the imaginary line VL can be set at any location within the scope of this disclosure where the maximum interval between adjacent intersections in the rolling direction is within the range of the present disclosure. For example, the imaginary line VL can be set in a region where the magnetic domain control processing line 11 is not provided. On the other hand, if no location is found where the maximum interval between adjacent intersections can be set to an imaginary line VL within the scope of this disclosure, it is presumed that the requirements of this disclosure are not met.

[0092] Furthermore, the magnetic domain image is output to a processing device, such as a personal computer (PC), equipped with an arithmetic unit, memory, display unit, input unit, and communication I / F, via cable or wireless communication. In the arithmetic unit, the magnetic domain structure is analyzed based on the magnetic domain image using the line segment method.

[0093] An example of determination using the line segment method will be given. Figure 3C These are magnetic domain images obtained using CMOS-MagView technology manufactured by Matesy GmbH. Additionally, Figure 3D It is shown schematically for the purpose of illustrating the measurement. Figure 3C The image.

[0094] In the segment method, the evaluation is performed by subtracting the segment Ls perpendicular to the domain. The segment spacing is drawn in a manner where there are 3 segments per 1 cm in the rolling direction RD. The domain width is derived based on the spacing w of the intersection point Ip of the 180° domain wall and the segment Ls. However, in the presence of closed domains 301 and noise 302, they are not counted as domain walls. Furthermore, when outputting the average domain width, the average spacing is calculated based on the length of each segment Ls and the number of intersection points Ip.

[0095] In the multiple domain control processing lines 11, the spacing of adjacent domain control processing lines 11 along the rolling direction RD is not particularly limited. A smaller spacing improves the effect of reducing iron loss. Conversely, a larger spacing improves noise characteristics. The spacing can be appropriately selected to correspond to the characteristics required by the oriented electromagnetic steel sheet 1. For example, the spacing of adjacent domain control processing lines 11 along the rolling direction RD can be set to 1.0 mm or more, 2.0 mm or more, 3.0 mm or more, or 5.0 mm or more. Alternatively, the spacing of adjacent domain control processing lines 11 along the rolling direction RD can be set to 10.0 mm or less, 9.0 mm or less, 8.0 mm or less, or 7.0 mm or less.

[0096] The spacing of adjacent domain control processing lines 11 along the rolling direction RD can be constant or non-uniform (variable). In the non-uniform case, for example, the average value of the spacing of adjacent domain control processing lines 11 along the rolling direction RD can be set to 1.0 mm or more, 2.0 mm or more, 3.0 mm or more, or 5.0 mm or more. Alternatively, the average value of the spacing of adjacent domain control processing lines 11 along the rolling direction RD can be set to 10.0 mm or less, 9.0 mm or less, 8.0 mm or less, or 7.0 mm or less. For the spacing, one or more straight lines L along the rolling direction RD are drawn, and the distance between two adjacent points LP at the intersection point LP of the straight line L and the domain control processing line is measured. When calculating the average spacing, the distance between multiple adjacent points LP is measured and averaged.

[0097] In the oriented electromagnetic steel sheet 1 of this embodiment, the spacing of VP in the imaginary line VL, which serves as the measurement position for the domain width, is uneven. That is, even if the average spacing of the domain control processing lines 11 is within the above-mentioned range, the imaginary line VL, which serves as the measurement position for the domain width, passes through areas where the domain control processing lines 11 are not provided, and thus the maximum value of the spacing between the intersection of the imaginary line VL and the domain control processing lines 11 in the rolling direction exceeds 20 mm.

[0098] The angle between the domain control processing line 11 and the rolling right-angle direction TD can be measured using a known angle measurement method after specifying the domain control processing line 11 and the rolling right-angle direction TD in the order described above and below.

[0099] The spacing of the domain control processing line 11 along the rolling direction RD can be measured using known length measurement methods after specifying the domain control processing line 11 and the rolling direction RD in the order described above and below.

[0100] Here, the spacing of the domain control processing lines 11 along the rolling direction RD is the distance from the center of the width of the domain control processing line in the rolling direction RD to the center of the width of the adjacent domain control processing line in the rolling direction RD.

[0101] Furthermore, when the magnetic domain control processing line 11 is subjected to thermal strain, it is preferable to introduce tensile stress into the thermal strain. The greater the tensile stress, the better the effect of improving iron loss. On the other hand, the smaller the tensile stress, the better the noise characteristics. It is possible to appropriately select the tensile stress corresponding to the characteristics required by the oriented electromagnetic steel sheet 1.

[0102] When the magnetic domain control processing line 11 is a slot, the greater the depth and width of the slot, the better the effect of improving iron loss. On the other hand, the smaller the depth and width of the slot, the better the noise characteristics. The shape of the slot can be appropriately selected to correspond to the characteristics required by the oriented electromagnetic steel sheet 1.

[0103] There is no particular limitation on the depth of the groove; for example, it is preferably set to 5μm to 50μm. The depth of the groove can also be set to 6μm or more, 7μm or more, or 10μm or more. Alternatively, the depth of the groove can be set to less than 48μm, 45μm or less, or 40μm or less.

[0104] The width of the groove (the width of the opening) is not particularly limited, but is preferably set to 10μm to 300μm. The width of the groove can also be specified as 20μm or more, 30μm or more, or 50μm or more. Alternatively, the width of the groove can be 280μm or less, 250μm or less, or 200μm or less. The depth and width of the groove can be the same or varied. In the case of variation, it is preferable that the average depth and width of multiple grooves fall within the above-mentioned range.

[0105] The depth and width of the groove can be determined by using a known three-dimensional measuring machine to measure the surface shape of a specific sample. In the case where the oriented electromagnetic steel sheet 1 has an insulating coating, the three-dimensional measurement of the sample surface is performed after removing the insulating coating according to the steps described above.

[0106] (Specific methods for rolling direction RD and rolling right angle direction TD)

[0107] The rolling direction RD and the rolling right-angle direction (plate width direction) TD of the orientation-oriented electromagnetic steel sheet 1 are specified by the following means.

[0108] (1) When the sample is cut from a coil of oriented electromagnetic steel sheet 1, the width direction of the coil is regarded as the rolling right-angle direction TD. In addition, the direction perpendicular to the rolling right-angle direction TD and the rolling surface normal direction ND is regarded as the rolling direction RD.

[0109] (2) In the case where the sample is cut from a component of an electric motor product, the rolling direction RD and the rolling right-angle direction TD are determined based on the rolling marks on the surface of the oriented electromagnetic steel sheet 1. The direction of extension of the rolling marks is regarded as the rolling direction RD. The direction perpendicular to the rolling direction RD and the normal direction ND of the rolling surface is regarded as the rolling right-angle direction TD.

[0110] (3) When it is difficult to specify the rolling direction RD and the rolling right-angle direction TD based on the surface marks of the oriented electromagnetic steel sheet 1, the rolling direction RD and the rolling right-angle direction TD are specified based on the crystal orientation of the oriented electromagnetic steel sheet 1. Specifically, the crystal orientation of the oriented electromagnetic steel sheet 1 to be evaluated is measured at multiple points. Moreover, the easy magnetization axis at which the crystal orientation at the measurement point forms an angle with the normal direction ND (thickness direction) of the rolling surface is closest to a right angle is selected. <001> The direction with the smallest offset angle is considered as the rolling direction RD, and the direction perpendicular to the rolling direction RD and the normal direction ND of the rolling surface is considered as the rolling right-angle direction (plate width direction) TD.

[0111] (Laminated)

[0112] Oriented electromagnetic steel sheet 1 may have a forsterite coating on its surface (i.e., the oriented electromagnetic steel sheet may include a base steel sheet and a forsterite coating formed on the surface of the base steel sheet). Additionally, oriented electromagnetic steel sheet 1 may have an insulating coating on the surface of the base steel sheet or the surface of the forsterite coating (i.e., the oriented electromagnetic steel sheet may include a base steel sheet, a forsterite coating formed on the surface of the base steel sheet, and an insulating coating formed on the surface of the forsterite coating; or it may include a base steel sheet and an insulating coating formed on the surface of the base steel sheet).

[0113] The magnesium olivine coating and the insulating coating can be formed on one side or both sides of the oriented electromagnetic steel sheet 1.

[0114] Forsterite coatings are, for example, inorganic coatings with magnesium silicate as the main component. Forsterite coatings are formed, for example, by reacting an annealing release agent containing magnesium oxide (MgO) applied to the surface of a base steel sheet with the surface composition of the base steel sheet during final annealing. For example, a forsterite coating has a composition derived from the annealing release agent and the base steel sheet (more specifically, a composition with Mg2SiO4 as the main component). On the other hand, when an annealing release agent mainly composed of Al2O3 is used in the final annealing, a forsterite coating sometimes does not form.

[0115] The insulating coating imparts electrical insulation and tensile strength to the oriented electromagnetic steel sheet 1. By applying tension to the oriented electromagnetic steel sheet 1, the movement of magnetic domain walls within the sheet becomes easier, thereby reducing iron loss. Furthermore, the insulating coating can impart various properties to the oriented electromagnetic steel sheet 1, such as corrosion resistance, heat resistance, and slip resistance. The insulating coating can be, for example, a known coating formed by applying a coating solution primarily composed of phosphate and colloidal silica to the surface of a magnesium olivine coating and then sintering it.

[0116] [Manufacturing Method]

[0117] The oriented electromagnetic steel sheet of this embodiment can achieve its desired effect as long as it possesses the above-mentioned characteristics regardless of the manufacturing method. However, the following method allows for stable manufacturing and is therefore preferred.

[0118] That is, the orientation-oriented electromagnetic steel sheet of this embodiment can be manufactured by a manufacturing method including the steps (I) to (III) below. In cases where the distribution of magnetic domain width is estimated by methods other than image acquisition, and the distribution of magnetic domain width is clear, steps (I) and (II) may be omitted. (I) Magnetic domain image acquisition process: to obtain magnetic domain images of oriented electromagnetic steel plates. (II) Region-specific process, based on the magnetic domain image obtained in the magnetic domain image acquisition process, a region in a specific orientation electromagnetic steel sheet with a magnetic domain width exceeding 500 μm. (III) Magnetic domain control processing line formation process: magnetic domain control processing lines are formed on the surface of the oriented electromagnetic steel sheet after the regional specific process.

[0119] Each process step is explained.

[0120] First, the orientation-oriented electromagnetic steel sheet (original sheet) supplied for the magnetic domain image acquisition process, or for the magnetic domain control processing line formation process without the magnetic domain image acquisition process or without the magnetic domain image acquisition process and the region-specific process, can be a known orientation-oriented electromagnetic steel sheet.

[0121] For example, the original plate, as a chemical composition, by mass%, may contain Si: 2.50~7.00%, Mn: 0~1.00%, C: 0~0.085%, acid-soluble Al: 0~0.065%, N: 0~0.012%, Cr: 0~0.300%, Cu: 0~0.400%, P: 0~0.500%, Sn: 0~0.300%, Sb: 0~0.300%, Ni: 0~1.000%, S: 0~0.015%, Se: 0~0.015%, Bi: 0~0.020%, Nb: 0~0.030%, V: 0~0.030%, Mo: 0~0.030%, Ta: 0~0.030%, W: 0~0.030%, B: 0~0.080%, Ti: 0~0.015%. The balance of the chemical composition includes Fe and impurities.

[0122] A magnesium olivine coating can also be formed on the surface of the oriented electromagnetic steel sheet that becomes the base plate.

[0123] (Magnetic domain image acquisition process)

[0124] (Regional specific process)

[0125] In the magnetic domain image acquisition process, a magnetic domain image of the surface of the orientation-oriented electromagnetic steel sheet is acquired before the magnetic domain control processing line formation process. In the region-specification process, based on the magnetic domain image obtained in the magnetic domain image acquisition process, a region in the orientation-oriented electromagnetic steel sheet with a magnetic domain width exceeding 500 μm is specified.

[0126] As mentioned above, in regions with small domain widths, the domain subdivision effect is small; in regions with domain widths of approximately 500 μm or less, it is considered that the domain subdivision effect brought about by domain control is almost negligible. Therefore, it is preferable not to perform domain control in these regions.

[0127] In the domain control line formation process, which is a subsequent process, by mainly performing domain control processing in areas where the domain width exceeds 500 μm, the number of domain control lines can be reduced, the deterioration of noise characteristics can be suppressed, and iron loss can be reduced.

[0128] (Magnetic domain control processing line formation process)

[0129] In the domain control processing line formation process, multiple domain control processing lines extending in a direction intersecting the rolling direction are formed on the surface of the oriented electromagnetic steel sheet by primarily forming domain control processing lines in regions with domain widths exceeding 500 μm, as specified by a region-specific process. At this time, the domain control processing lines are formed such that regions with intervals exceeding 20 mm in the rolling direction exist.

[0130] As a method, for example, the following approach can be cited: based on the distribution of domain widths obtained in a region-specific process, a domain control processing line is formed along a direction intersecting the rolling direction at a position that has been moved more than 20 mm relative to the adjacent domain control processing line in the rolling direction; or as... Figure 1A As shown, when a magnetic domain control processing line is formed along a direction intersecting the rolling direction, even if the starting point is within 20 mm of the adjacent magnetic domain control processing line in the rolling direction, a magnetic domain control processing line is not formed in a certain range. Thus, a magnetic domain control processing line is formed at a certain position with an interval of more than 20 mm in the rolling direction between adjacent intersections.

[0131] The domain control processing lines can be either thermally strained or formed by grooves. In the case of thermal strain, the domain control processing lines are formed by irradiation with a laser or electron beam. The irradiation conditions can be within a known range.

[0132] To form a groove, methods such as irradiating with lasers or electron beams, mechanical processing based on gears, and chemical processing based on etching can be used.

[0133] As long as the formation direction of the domain control processing line (or the scanning direction if it is a laser, etc.), the spacing of the rolling direction RD of the domain control processing line, the width of the domain control processing line, and the depth of the groove if it is a groove, are within the range of the orientation electromagnetic steel sheet of this embodiment described above, they can be controlled by known methods.

[0134] (Specific methods in the magnetic domain image acquisition process ~ formation of each magnetic domain control processing line)

[0135] The acquisition of magnetic domain images and the identification of regions with domain widths exceeding 500 μm can be performed using the following methods.

[0136] The domain image can be acquired, for example, by an image acquisition device. Then, the distribution of the widths (domain widths) of the 180° domains is derived from the domain image. The distribution of domain widths in the original plate can be derived, for example, by using a resolution device.

[0137] Regions with a domain width greater than a specified value (e.g., exceeding approximately 500 μm) are designated as regions for which domain control processing should be performed (hereinafter sometimes referred to as processing regions).

[0138] The processing area can also be determined by the operator visually observing the magnetic domain image displayed on the display of the analysis device.

[0139] Figure 4 An example of the hardware configuration of an image acquisition device 30 for acquiring magnetic domain images of the original board (oriented electromagnetic steel board 1 before magnetic domain control processing) is shown. The image acquisition device 30 includes a light source unit 31, a magneto-optical sensor (MO sensor 33), an image sensor 35, and a signal processing unit 37.

[0140] The light source unit 31 has a light source composed of light-emitting diodes (LEDs) that illuminates the MO sensor 33 with light of the same polarization plane.

[0141] The MO sensor 33 is a device for measuring the magnetic domain structure of a magnetic material. The MO sensor 33 has an observation surface on which the magnetic material sample to be measured is placed. Light irradiated from the light source 31 is reflected by a reflective layer inside the MO sensor 33. The reflected light passes through the interior of the MO sensor 33 again and is output to the exterior of the MO sensor 33. When the original plate, which is the magnetic material sample, is placed on the observation surface of the MO sensor 33, a leakage magnetic field corresponding to the spontaneous magnetization of the original plate is generated inside the MO sensor 33. Through this leakage magnetic field, the polarization plane of the reflected light rotates.

[0142] Image sensor 35 is a complementary metal-oxide-semiconductor (CMOS) image sensor. Image sensor 35 images the reflected light from MO sensor 33 onto the light-receiving surface and performs photoelectric conversion, outputting the converted analog signal to signal processing unit 37. By detecting the reflected light after the polarization plane is rotated using image sensor 35, the distribution of the leakage magnetic field can be obtained, and the magnetic domain structure of the original plate becomes clear.

[0143] The signal processing unit 37 includes an amplifier, an analog-to-digital converter (ADC), and a digital signal processor (DSP). The analog signal output from the image sensor 35 is amplified by the amplifier. Then, the analog signal is converted into a digital signal by the ADC. An image signal is generated by performing prescribed digital processing on the digital signal using the DSP. The image signal generated by the signal processing unit 37 is output to the analysis device 40 (see reference 40) via cable or wireless communication. Figure 5 ).

[0144] Figure 5 The hardware configuration of the analysis device 40 for analyzing the magnetic domain structure of the original board is shown. The analysis device 40 is a computer device such as a personal computer (PC). The analysis device 40 includes an arithmetic unit 41, a memory 43, a display unit 45, an input unit 47, and a communication I / F 49.

[0145] The arithmetic unit 41 has a central processing unit (CPU). The arithmetic unit 41 parses the domain structure from the domain image of the substrate according to a program stored in the memory 43. Then, the arithmetic unit 41 determines the processing area for which domain control processing is applied. The processing performed by the arithmetic unit 41 will be described in detail later.

[0146] The memory 43 includes a read-only memory (ROM) and a random access memory (RAM). The ROM stores programs executed by the CPU of the arithmetic unit 41 and the data required to execute these programs. The programs and data stored in the RAM are loaded into the RAM and executed.

[0147] The memory 43 may also be a magnetic storage device such as a hard disk drive (HDD) or an optical storage device such as an optical disc. Alternatively, the memory 43 may be removable from the parsing device 40 and store programs and data on a computer-readable recording medium. Alternatively, the memory 43 may also receive programs executed by the arithmetic unit 41 from a network via the communication I / F 49.

[0148] Display unit 45 includes a liquid crystal display (LCD), a plasma display, or an organic electroluminescent (EL) display. Display unit 45 displays an image based on an image signal output from image acquisition device 30. Additionally, display unit 45 displays the analysis results based on the magnetic domain structure of arithmetic unit 41.

[0149] Input unit 47 includes input devices such as a mouse and keyboard. Communication I / F 49 is an interface for sending and receiving data with external devices via networks such as local area networks (LANs), wide area networks (WANs), and the Internet.

[0150] As the computing unit 41, it can also replace general-purpose hardware such as CPUs and adopt special-purpose integrated circuits (ASICs) or field-programmable gate arrays (FPGAs) specifically designed for the analysis of magnetic domain structures.

[0151] Figure 4 and Figure 5 The illustration shows a case where the image acquisition device 30 and the resolution device 40 are different devices, but a system integrating the image acquisition device 30 and the resolution device 40 can also be used.

[0152] As a means of introducing thermal strain onto the surface of the original plate, known methods such as laser irradiation, electron beam irradiation, and ion implantation can be used. As a means of forming grooves on the surface of the original plate, known methods such as laser irradiation, electron beam irradiation, and machining can be used. The configuration of the laser irradiation device 500 for introducing thermal strain by laser irradiation will be described below.

[0153] Figure 6 The configuration of the laser irradiation device 500 is shown. The laser irradiation device 500 includes a polygon mirror 501, a light source device 503, a collimator 505, a condenser lens 507, a motor 509, a sensor 511, a control unit 513, and a through plate device 515.

[0154] The plate-passing device 515 causes the original plate to pass through in the rolling direction RD.

[0155] The polygon mirror 501 is, for example, a regular polygonal prism. Multiple plane mirrors are respectively provided on multiple sides of the polygon mirror 501 that constitute the regular polygonal prism. The laser beam LB is incident from the light source device 503 through the collimator 505 in one direction (horizontal direction) onto the plane mirror of the polygon mirror 501 and is reflected by the plane mirror.

[0156] The polygon mirror 501 can rotate around the rotation axis O1 driven by the motor 509. Depending on the rotation angle of the polygon mirror 501, the incident angle of the laser beam LB relative to the plane mirror changes sequentially. Therefore, the reflection direction of the laser beam LB changes sequentially, enabling it to scan the surface of the original plate. Figure 6 The symbol P represents the interval between adjacent magnetic domain control processing lines 11, that is, the irradiation spacing of the laser beam LB.

[0157] Under the control of the control unit 513, the light source device 503 outputs a laser beam LB in a prescribed irradiation mode (e.g., continuous irradiation mode or pulse irradiation mode).

[0158] A condenser lens 507 is disposed in the optical path of the laser beam LB reflected from the polygon mirror 501. The condenser lens 507 constitutes a condenser optical system with a specified focal length. The laser beam LB reflected from the polygon mirror 501 is focused onto the surface of the original plate by the condenser lens 507, thereby introducing thermal strain onto the surface of the original plate.

[0159] Motor 509 is connected to polygon mirror 501. Motor 509 rotates and drives polygon mirror 501 under the control of control unit 513.

[0160] Sensor 511 is connected to the drive shaft of motor 509. Sensor 511 detects the rotation angle of the polygon mirror 501 rotated by motor 509. In addition, sensor 511 outputs a signal indicating the detected rotation angle (hereinafter referred to as rotation angle signal) to control unit 513.

[0161] The control unit 513 is composed of a processor. The control unit 513 is connected to the light source device 503, the motor 509, the sensor 511, and the through-plate device 515. The control unit 513 receives speed signal input from the through-plate device 515. Furthermore, the control unit 513 outputs a signal to the motor 509 instructing the rotation drive of the polygon mirror 501.

[0162] Furthermore, the control unit 513 controls the switching on and off of the power of the laser beam LB output by the light source device 503 based on the stress input signal indicating the processing area and the rotation angle signal output from the sensor 511. When the laser irradiation device 500 is electrically connected to the analysis device 40, the stress input signal is input from the analysis device 40 to the laser irradiation device 500. The stress input signal can also be input to the laser irradiation device 500 by the operator.

[0163] Next, an example of a method for determining the processing area will be described in detail. The processing for a specific processing area is performed, for example, by the arithmetic unit 41 of the parsing device 40.

[0164] The arithmetic unit 41 uses, for example, the line segment method to derive the distribution of the magnetic domain width of the original board. Then, the arithmetic unit 41 determines the regions with magnetic domain widths above a predetermined value (e.g., exceeding approximately 500 μm) as the areas where magnetic domain control processing is preferentially applied.

[0165] In the line segment method, evaluation is performed by subtracting line segments perpendicular to the magnetic domains. The line segments are spaced out in groups of three per 1 cm in a direction parallel to the magnetic domain. The domain width is derived based on the intervals between the intersections of the 180° domain walls and the line segments.

[0166] Figure 3A This paper presents an example of the distribution of magnetic domain widths in an orientation-controlled electromagnetic steel plate 1 before magnetic domain control processing, obtained by further analyzing a magnetic domain image acquired through a CMOS-MagView image manufactured by Matesy GmbH using a two-dimensional Fourier transform. Figure 3B Showing with Figure 3A The same principles can be obtained, for Figure 3A The distribution of magnetic domain widths after magnetic domain control treatment is applied to the surface of the oriented electromagnetic steel sheet 1. This magnetic domain control treatment is achieved by continuous-wave laser irradiation along a direction approximately perpendicular to the rolling direction RD. Figures 3A-3B In this context, the unit of measurement is μm.

[0167] As an example of analysis using two-dimensional Fourier transform, a method for deriving the distribution of magnetic domain widths is explained using the short-term Fourier transform (hereinafter referred to as "ST2DFT"), which extends the short-term Fourier transform, one of the earliest signal processing methods used in the time / frequency analysis of sound signals, to a two-dimensional region.

[0168] The image (magnetic domain image) represented by the image signal acquired by the image acquisition device 30 is labeled as x(k, l) as a data string of two-dimensional coordinates (kl coordinates). In this embodiment, the magnetic domain image to be analyzed is an image binarized with two colors, or an image represented with three or more color levels (multi-level) such as grayscale.

[0169] In order to derive the distribution of the domain width of the original plate 2, the arithmetic unit 41 performs the following processes (A-1), (A-2) and (A-3). (A-1) Processing of cutting out multiple partial regions from magnetic domain images (A-2) Perform ST2DFT processing (A-3) Processing for deriving the distribution of magnetic domain widths The following section provides a detailed explanation of the processing of A-1 to A-3.

[0170] (A-1) Processing of cutting out multiple partial regions from magnetic domain images

[0171] To extract multiple regions from the magnetic domain image and analyze their respective frequency structures, the range of the k-direction is set to 0 ≤ k ≤ N. k -1. Set the range of the l-direction to 0 ≤ l ≤ N l The window function Wa(k, l)(N) for a rectangular window of -1 k and N l (where k is a natural number). As a window function Wa(k, l), it can be used with Hamming windows, Hanning windows, Blackman windows, etc.

[0172] The observation position in the data string x(k, l) of the magnetic domain image is represented by the index (n, m), and the displacement of the window function Wa(k, l) in the k and l directions is represented by S.k and S l Time (n, m, S) k S l (where n is an integer), as shown in equation (1), nS is obtained by cutting out the magnetic domain image. k ≤k≤nS k +N k -1, mS l ≤l≤mS l +N l The data string x in the range of -1 is a partial region of the data string. nm (k-nS) k ,l-mS l ).

[0173] [Mathematical Expression 1]

[0174] Figure 7 Examples are shown of partial regions cut from the magnetic domain image G corresponding to the observation positions (n, m) = (1,1), (2,2), (3,3), ..., (P, Q) (P and Q are natural numbers).

[0175] In this embodiment, the range of N for a specific window function Wa(k,l) k and N l These are the parameters corresponding to the number of pixels in the k-direction and the number of pixels in the l-direction of a given region, respectively.

[0176] (A-2) Perform ST2DFT processing

[0177] Define a portion of the data string as x nm (n′, m′) = x nm (k-nS) k ,l-mS l ), for x nm When performing a two-dimensional Fourier transform on (n′, m′), as shown in equation (2), a partial Fourier image X(f) corresponding to a portion of the region at the observation position (n, m) is obtained. k f l (n, m).

[0178] [Mathematical Expression 2]

[0179] Here, f k and f l It is spatial frequency.

[0180] When the spatial frequency f k The resolution is expressed as Δf k , the spatial frequency f lThe resolution is expressed as Δf l When, Δf k and Δf l Defined as in equation (3).

[0181] [Mathematical Expression 3]

[0182] Here, Δk and Δl represent the spatial resolution in the k-direction and the spatial resolution in the l-direction of the magnetic domain image, respectively.

[0183] For example, when on Figure 7 The data strings x for each of the shown regions nm (k-nS) k ,l-mS l When performing a two-dimensional Fourier transform, such as Figure 8 As shown, a partial Fourier image X(f) is obtained at each observation position (n, m). k f l (n, m).

[0184] (A-3) Processing for deriving the distribution of magnetic domain widths

[0185] When a partial Fourier image X(f) is obtained k , f l When (f, n, m), calculate the partial Fourier image X(f) k , f l The coordinates of the peak position of the point (k-component f) at (n,m). k max (n, m) and l component f l max (n, m)). Regarding the derivation of peak positions, the regions near k=0 and l=0 are largely dependent on the image contrast, and therefore are excluded.

[0186] Then, based on the resolution of the spatial frequency defined by Equation (3) and the peak position of the points of the partial Fourier image, the distribution L(n, m) of the magnetic domain width is derived as in Equation (4).

[0187] [Mathematical Expression 4]

[0188] Thus, by using ST2DFT, the distribution L(n, m) of the magnetic domain width can be quantitatively derived while preserving the positional information of the magnetic domain image.

[0189] When the arithmetic unit 41 calculates the distribution of magnetic domain widths, it determines the regions with magnetic domain widths greater than or equal to a predetermined value as processing regions (i.e., regions where magnetic domain control processing is applied). The control unit 513 of the laser irradiation device 500 turns on the power of the laser beam LB to the processing region, and preferably controls it to turn off the power of the laser beam LB to regions outside the processing region. As a result, the magnetic domain control processing line 11 is introduced into the processing region of the original board. In addition, the introduction of the magnetic domain control processing line 11 is suppressed in other regions.

[0190] Through the above steps, a magnetic domain image of the orientation-controlled electromagnetic steel sheet 1 can also be obtained. In the magnetic domain image of the orientation-controlled electromagnetic steel sheet 1, the magnetic domain control processing line 11 is sometimes unclear. In this case, in order to clearly identify the magnetic domain control processing line 11, the observation conditions can be adjusted. For example, by applying a DC magnetic field perpendicular to the surface (thickness direction) of the orientation-controlled electromagnetic steel sheet 1, the magnetic domain control processing line 11 can be made clearer.

[0191] (Insulation coating formation process)

[0192] When an insulating film is formed on the surface of a grain-oriented electromagnetic steel sheet, an insulating film forming process can be included, in which the insulating film is formed using a known method after final annealing. The insulating film forming process can be performed after final annealing, either before or after the magnetic domain control line forming process. However, when forming the insulating film before the magnetic domain control line forming process, the insulating film sometimes peels off from the magnetic domain control line 11; therefore, it is preferable to perform the process after the magnetic domain control line forming process. If the insulating film forming process is performed before the magnetic domain control line forming process, it is preferable to re-form the insulating film on the magnetic domain control line 11 after the magnetic domain control line forming process.

[0193] Example

[0194] The effects of the present invention are further illustrated through examples. However, the conditions in the examples are merely one example used to confirm the feasibility and effects of implementing the present invention. The present invention is not limited to this single example. Various conditions can be used to achieve the purpose of the present invention as long as they do not depart from its spirit.

[0195] (Example 1)

[0196] Oriented electromagnetic steel sheets from the same batch with a thickness of 0.20 mm were used as the base plates.

[0197] For the original board, magnetic domain control processing is performed in a manner that conforms to the types and shapes of the magnetic domain control processing lines shown in Table 1. Here, the shapes of the magnetic domain control processing lines A~E and A-2 in the table are shown below. A: Straight magnetic domain control processing lines are formed in regions where the magnetic domain width exceeds the specified value (500μm). B: Magnetic domain control processing lines are formed in a straight line across the entire width of the original board. C: Forming regular dashed magnetic domain control processing lines. D: Forms random, dashed magnetic domain control processing lines. E: Magnetic domain control processing lines are formed only in the region within ±4 mm of the rolling direction from the center of each grain in the rolling direction, at 4 mm intervals. The radius of curvature of the steel plate at the original location of this grain during final annealing is 250 mm. A-2: Form a linear magnetic domain control processing line containing curves in the region where the magnetic domain width exceeds the specified value (500μm).

[0198] The specific regions with magnetic domain widths exceeding 500 μm were determined using the methods described above.

[0199] The noise and iron loss of the oriented electromagnetic steel sheet after the magnetic domain control treatment were evaluated and recorded in Table 2.

[0200] The evaluation methods for noise and iron loss are as follows. First, 205 sheets of 0.20mm thick oriented electromagnetic steel plates were stacked to fabricate three-phase transformer cores. The width of the legs and yoke of the three-phase transformer cores was 150mm. The height and width of the three-phase transformer cores were both 750mm. The noise and iron loss of these three-phase transformer cores were measured. The measurement conditions were set as follows: frequency: 50Hz and excitation flux density: 1.5T.

[0201] During noise measurement, microphones were placed at equal intervals at eight locations around the transformer where the three-phase transformer core was assembled. The distance between the transformer and the microphones was set to 30 cm. The noise measurement results from these microphones were corrected for A-characteristics and averaged to obtain the noise evaluation results (in dBA) for the oriented electromagnetic steel sheet, and are recorded in Table 2. Examples with noise evaluation results of 25.1 dBA or less were judged as examples of achieving low noise. Noise evaluation results judged as unqualified were marked with an underline.

[0202] As described above, the iron loss was determined by measuring the voltage and current on the primary and secondary sides using a power analyzer when energized at a frequency of 50 Hz and an excitation flux density of 1.5 T. The calculated iron loss, as the evaluation results (in W / kg) for oriented electromagnetic steel sheets, is recorded in Table 2. Examples with an iron loss evaluation result of 0.580 W / kg or less were deemed to have achieved low iron loss. Noise evaluation results deemed unqualified are underlined.

[0203] Furthermore, rectangular samples with a length of 100 mm on both sides were cut from the core of the three-phase transformer used for noise and iron loss measurement.

[0204] In this rectangular sample, a square evaluation area is defined with one side having a length of 50 mm and the other side being parallel to the rolling direction. Inside the evaluation area, imaginary lines VL, each 50 mm long and parallel to the rolling direction, are defined at 5 mm intervals along a direction perpendicular to the rolling direction. The total number of imaginary lines is 9.

[0205] In each of the nine imaginary lines VL, the maximum value of the interval between adjacent intersections in the rolling direction (intersection interval), the average value of the domain width measured along the imaginary line, and the maximum value of the domain width measured along the imaginary line were determined according to the above-mentioned method.

[0206] Table 1 shows the number of imaginary lines whose maximum interval between intersection points exceeds 20 mm, the average value of the domain width in imaginary lines whose maximum interval between intersection points exceeds 20 mm, and the number of imaginary lines whose maximum value is below a specified value.

[0207]

[0208]

[0209] As shown in Tables 1 and 2, when a magnetic domain control treatment line is formed in a region where the domain width exceeds the specified value (500 μm) (samples No. 1~15, 20, 21), in at least one imaginary line, the maximum interval between adjacent intersections of the imaginary line and the magnetic domain control treatment line in the rolling direction exceeds 20 mm, and the average domain width measured along the imaginary line is less than 600 μm or the maximum value is less than 1200 μm. As a result, iron loss is low and noise is also low.

[0210] In contrast, when the domain control processing lines are regular or random dashed lines, or when the domain control processing lines are formed only in a portion of the central region of each grain's rolling direction, the maximum value of the interval between adjacent intersections of the imaginary line and the domain control processing lines in the rolling direction, or the average and maximum values ​​of the domain widths measured along the imaginary line, deviate from the scope of this invention. As a result, one or both of the iron loss characteristics and noise characteristics are poor.

[0211] (Example 2)

[0212] Oriented electromagnetic steel sheets (oriented electromagnetic steel sheets with coarse grain size) from the same batch with a thickness of 0.20 mm were used as the base sheet. The electromagnetic steel sheet was produced by ensuring that the average heating rate from 1000°C to 1200°C was less than 5°C / hour during the final annealing process, and the average grain boundary spacing relative to the rolling direction RD was 31 mm to 40 mm.

[0213] For the original board, magnetic domain control processing is performed in a manner that conforms to the types and shapes of the magnetic domain control processing lines shown in Table 3. Here, the shapes of the magnetic domain control processing lines A~E and A-2 in the table are shown below. A: Straight magnetic domain control processing lines are formed in regions where the magnetic domain width exceeds the specified value (500μm). B: Magnetic domain control processing lines are formed in a straight line across the entire width of the original board. C: Forming regular dashed magnetic domain control processing lines. D: Forms random, dashed magnetic domain control processing lines. E: Magnetic domain control processing lines are formed only in the region within ±4 mm of the rolling direction from the center of each grain in the rolling direction, at 4 mm intervals. The radius of curvature of the steel plate at the original location of this grain during final annealing is 250 mm. A-2: Form a linear magnetic domain control processing line containing curves in the region where the magnetic domain width exceeds the specified value (500μm).

[0214] The specific determination of regions with a domain width exceeding 500 μm was carried out using the same method as in Example 1.

[0215] Noise and iron loss were evaluated using the same methods as in Example 1. The results are shown in Table 4.

[0216]

[0217]

[0218] As shown in Tables 3 and 4, when a magnetic domain control treatment line is formed in a region where the domain width exceeds the specified value (500 μm) (samples No. 31~45, 50, 51), in at least one imaginary line, the maximum interval between adjacent intersections of the imaginary line and the magnetic domain control treatment line in the rolling direction exceeds 30 mm, and the average value of the magnetic domain width measured along the imaginary line is less than 600 μm or the maximum value is less than 1200 μm. As a result, iron loss is low and noise is also low.

[0219] In contrast, when the domain control processing lines are regular or random dashed lines, or when the domain control processing lines are formed only in a portion of the central region of each grain's rolling direction, the maximum value of the interval between adjacent intersections of the imaginary line and the domain control processing lines in the rolling direction, or the average and maximum values ​​of the domain widths measured along the imaginary line, deviate from the scope of this invention. As a result, one or both of the iron loss characteristics and noise characteristics are poor.

[0220] Industrial availability According to this disclosure, a method for manufacturing an orientation-oriented electromagnetic steel sheet with low iron loss (low iron loss) and low noise when manufactured into an electric motor product is provided. Therefore, it has high potential for industrial application.

[0221] Explanation of reference numerals in the attached figures 1. Oriented Electromagnetic Steel Sheet 11 Magnetic Domain Control Processing Line RD rolling direction TD rolling right-angle direction (plate width direction) ND (Normal direction of the rolled surface) VL Imaginary Line VP intersection 30 Image Acquisition Device 31 Light Source Section 33 MO sensor 35 Image Sensor 37. Signal Processing Department 40 Analysis device 41. Arithmetic Unit 43 Memory 45 Display Section 47 Input Section 49 Communication I / F 301 Closed Magnetic Domains 302 Noise Ls line segment IP intersection 500 laser irradiation device 501 Multifaceted Mirror 503 Light Source Device 505 Collimator 507 Condensing Lens 509 motor 511 sensor 513 Control Department 515 Through-plate device

Claims

1. A type of oriented electromagnetic steel sheet, characterized in that, The surface has multiple magnetic domain control processing lines extending in a direction intersecting the rolling direction. An evaluation area is defined on the surface as a square with one side length of 50 mm and one side parallel to the rolling direction. Furthermore, within the evaluation area, imaginary lines of 50 mm length and parallel to the rolling direction are defined at 5 mm intervals along a direction perpendicular to the rolling direction. In at least one of the imaginary lines, among the multiple intersections of the imaginary line and the plurality of magnetic domain control processing lines, the maximum value of the interval between adjacent intersections in the rolling direction exceeds 20 mm, and the average value of the magnetic domain width measured along the imaginary line is less than 600 μm.

2. The oriented electromagnetic steel sheet according to claim 1, characterized in that, The average value of the domain width measured along the imaginary line is less than 500 μm.

3. The oriented electromagnetic steel sheet according to claim 1, characterized in that, In each of the imaginary lines in two or more rolling directions where the maximum value of the interval exceeds 20 mm, the average value of the magnetic domain width measured along the imaginary line is less than 600 μm.

4. The oriented electromagnetic steel sheet according to claim 3, characterized in that, In each of the imaginary lines in two or more rolling directions where the maximum value of the interval exceeds 20 mm, the average value of the domain width measured along the imaginary line is less than 500 μm.

5. The oriented electromagnetic steel sheet according to claim 1, characterized in that, The maximum value of the interval in the rolling direction exceeds 30 mm.

6. A type of oriented electromagnetic steel sheet, characterized in that, The surface has multiple magnetic domain control processing lines extending in a direction intersecting the rolling direction. An evaluation area is defined on the surface as a square with one side length of 50 mm and one side parallel to the rolling direction. Furthermore, within the evaluation area, imaginary lines of 50 mm length and parallel to the rolling direction are defined at 5 mm intervals along a direction perpendicular to the rolling direction. In at least one of the imaginary lines, among the multiple intersections of the imaginary line and the plurality of magnetic domain control processing lines, the maximum value of the interval between adjacent intersections in the rolling direction exceeds 20 mm, and the maximum value of the magnetic domain width measured along the imaginary line is less than 1200 μm.

7. The oriented electromagnetic steel sheet according to claim 6, characterized in that, The maximum value of the domain width measured along the imaginary line is less than 800 μm.

8. The oriented electromagnetic steel sheet according to claim 6, characterized in that, In each of the imaginary lines in two or more rolling directions where the maximum value of the interval exceeds 20 mm, the maximum value of the magnetic domain width measured along the imaginary line is less than 1200 μm.

9. The oriented electromagnetic steel sheet according to claim 6, characterized in that, In each of the imaginary lines in two or more rolling directions where the maximum value of the interval exceeds 20 mm, the maximum value of the magnetic domain width measured along the imaginary line is less than 800 μm.

10. The oriented electromagnetic steel sheet according to claim 6, characterized in that, The maximum value of the interval in the rolling direction exceeds 30 mm.

11. The orientation-oriented electromagnetic steel sheet according to any one of claims 1 to 10, characterized in that, The multiple magnetic domain control processing lines are slots.

12. The orientation-oriented electromagnetic steel sheet according to any one of claims 1 to 10, characterized in that, The multiple magnetic domain control processing lines are thermal strain.

13. A method for manufacturing an orientation-oriented electromagnetic steel sheet, characterized in that, It is a method for manufacturing the oriented electromagnetic steel sheet according to any one of claims 1 to 10, comprising: The magnetic domain image acquisition process obtains a magnetic domain image of the surface of the oriented electromagnetic steel plate; A region-specific process, based on the magnetic domain image obtained in the magnetic domain image acquisition process, identifies a region in the orientation electromagnetic steel sheet with a magnetic domain width exceeding 500 μm; as well as The magnetic domain control processing line forming process forms magnetic domain control processing lines on the surface of the orientation electromagnetic steel sheet after a specific process in the region. In the domain control processing line formation process, the domain control processing line is formed in the region where the domain width exceeds 500 μm.

14. The method for manufacturing an orientation-oriented electromagnetic steel sheet according to claim 13, characterized in that, In the magnetic domain control processing line formation process, the magnetic domain control processing line is formed by irradiation with a laser or electron beam.

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