wound core

Abstract

The present application provides a kind of winding core, which is in the side view with the winding core body being formed by laminating multiple polygonal ring-shaped direction electromagnetic steel sheet, the planar portion and the curved portion of direction electromagnetic steel sheet are alternately continuous in length direction, in the planar portion near at least one curved portion, if the three-dimensional crystal orientation difference between the two adjacent points in the point series arranged at equal intervals in the extension direction of curved portion is set as Φ, the total number of measured data of Φ is set as Nx, the number of data satisfying Φ ≥1.0 ° is set as Nt, the number of data satisfying Φ is 1.0 ° or more and less than 2.5 ° is set as Na, the number of data satisfying Φ is 2.5 ° or more and less than 4.0 ° is set as Nb, the number of data satisfying Φ is 4.0 ° or more is set as Nc, then the following formula (1)-(4) are satisfied.0.10≤Nt / Nx≤0.80(1)0.37≤Nb / Nt≤0.80(2)1.07≤Nb / Na≤4.00(3)Nb / Nc≥1.10(4).

Description

Technical Field

[0001] This invention relates to a wound core. This application claims priority based on Japanese Patent Application No. 2020-179267, filed on October 26, 2020, the contents of which are incorporated herein by reference. Background Technology

[0002] Directional electromagnetic steel sheets are steel sheets containing less than 7% by mass of Si and exhibiting a secondary recrystallization texture with secondary recrystallized grains aggregated in the {110}<001> orientation (Goss orientation). The magnetic properties of directional electromagnetic steel sheets are significantly affected by the degree of aggregation in the {110}<001> orientation. In recent years, practical directional electromagnetic steel sheets have been controlled by ensuring that the angle between the <001> direction of the crystal and the rolling direction falls within a range of approximately 5°.

[0003] Directional electromagnetic steel sheets are used in transformer cores and other applications through lamination, but high magnetic flux density and low iron loss are required as key magnetic properties. It is known that crystal orientation is closely related to these properties. For example, patent documents 1-3 disclose a precise orientation control technique that distinguishes the actual crystal orientation of the directional electromagnetic steel sheet from the ideal {110} by means of offset angles α around the normal direction of the rolling surface, β around the right-angle direction of the rolling surface, and γ around the rolling direction. <001> Orientation deviation.

[0004] In addition, the manufacturing of wound iron cores is known in the past, for example, by a method described in Patent Document 4. In this method, after the steel sheet is rolled into a cylindrical shape, it is pressed in its original cylindrical laminate form to make the corners have a constant curvature. After being shaped into a roughly rectangular shape, stress is relieved and the shape is maintained by annealing.

[0005] On the other hand, as another manufacturing method for wound iron cores, patent documents 5-7 disclose techniques such as those described above. In this technique, the steel plate portion that forms the corner of the wound iron core is pre-bent to create a small bending region with a radius of curvature of 3 mm or less, and the bent steel plate is stacked to form the iron core. According to this manufacturing method, the large pressing process as in the past is not required, and the steel plate can be precisely bent to maintain the shape of the iron core. Since the processing strain is concentrated only in the bending portion (corner), the stress relief using the aforementioned annealing process can be omitted, resulting in significant industrial advantages and expanding applications.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2001-192785

[0009] Patent Document 2: Japanese Patent Application Publication No. 2005-240079

[0010] Patent Document 3: Japanese Patent Application Publication No. 2012-052229

[0011] Patent Document 4: Japanese Patent Application Publication No. 2005-286169

[0012] Patent Document 5: Japanese Patent No. 6224468

[0013] Patent Document 6: Japanese Patent Application Publication No. 2018-148036

[0014] Patent Document 7: Australian Patent Application Publication No. 2012337260 Summary of the Invention

[0015] The problem that the invention aims to solve

[0016] The object of the present invention is to provide a wound iron core that improves the way in which the core efficiency deterioration associated with the bending process is suppressed in a wound iron core manufactured by a method of pre-bending a steel plate to form a small bending region with a curvature radius of less than 5 mm and stacking the bent steel plate to form the wound iron core.

[0017] Methods for solving problems

[0018] The inventors have conducted a detailed study on the efficiency of transformer cores manufactured by a method of pre-bending steel sheets to form a small bending region with a radius of curvature of 5 mm or less, and then stacking the bent steel sheets to form a wound core. The results showed that even when using steel sheets with approximately the same crystal orientation control, and with approximately the same magnetic flux density and iron loss measured on a single sheet, differences in core efficiency sometimes occurred.

[0019] The cause was investigated, and it was speculated that the efficiency difference that caused the problem was due to the difference in the degree of iron loss degradation of each raw material during bending.

[0020] Based on this perspective, various steel plate manufacturing conditions and core shapes were studied, and their effects on core efficiency were categorized. The results showed that by using steel plates manufactured under specific conditions as core raw materials with specific dimensions and shapes, the core efficiency could be controlled to achieve the optimal efficiency commensurate with the magnetic properties of the steel plate raw materials.

[0021] The present invention was made in view of the above-mentioned problems, and its main purpose is as follows.

[0022] One embodiment of the present invention relates to a wound iron core, which is a wound iron core body that is generally polygonal in shape when viewed from the side, characterized in that:

[0023] The wound core body comprises a portion formed by stacking directional electromagnetic steel plates in the thickness direction, with alternating planar portions and curved portions in the length direction, and has a stacked structure that appears roughly polygonal in side view.

[0024] The inner side curvature radius r of the curved portion in the side view is more than 1 mm and less than 5 mm;

[0025] In the directional electromagnetic steel plate,

[0026] Its chemical composition, expressed as a percentage by mass, contains:

[0027] Si: 2.0–7.0%

[0028] The remaining portion includes Fe and impurities.

[0029] It has a texture oriented towards the Goss orientation; and

[0030] In one or more of the planar portions adjacent to at least one of the curved portions, the following equations (1) to (4) are satisfied.

[0031] 0.10≤Nt / Nx≤0.80 (1)

[0032] 0.37≤Nb / Nt≤0.80 (2)

[0033] 1.07≤Nb / Na≤4.00 (3)

[0034] Nb / Nc≥1.10 (4)

[0035] Here, Nx in the formula (1) is: when multiple measuring points are arranged at 5mm intervals in the region of the planar portion adjacent to the curved portion, in the parallel direction parallel to the boundary of the curved portion and the planar portion, i.e. the boundary of the curved portion, in the parallel direction, the total number of grain boundary determination points that exist in the center of two adjacent measuring points in the parallel direction for determining whether there is a grain boundary between the two measuring points.

[0036] Furthermore, regarding the crystal orientation observed in the directional electromagnetic steel sheet,

[0037] The offset angle from the ideal Goss orientation, with the normal direction Z of the rolled surface as the axis of rotation, is defined as α.

[0038] The offset angle from the ideal Goss orientation, with the rolling right-angle direction C as the rotation axis, is defined as β.

[0039] The offset angle from the ideal Goss orientation with the rolling direction L as the rotation axis is defined as γ.

[0040] When the offset angles of the crystal orientation measured at the two measurement points are expressed as (α1,β1,γ1) and (α2,β2,γ2), the angle Φ obtained by the following equation (6) is... 3D When defining the three-dimensional orientation difference of the offset angles α, β, and γ,

[0041] In equations (1) and (2), Nt is: satisfying Φ 3D The number of grain boundary criteria points ≥1.0°

[0042] In equation (3), Na is: satisfying Φ 3D The number of grain boundary criteria points with a gradient greater than 1.0° and less than 2.5°.

[0043] In equations (2) and (3), Nb is: satisfying Φ 3D The number of grain boundary criteria points with a gradient greater than 2.5° and less than 4.0°.

[0044] In equation (4), Nc is: Φ 3D The number of grain boundary determination points above 4.0°;

[0045] Φ 3D =[(α2-α1) 2 +(β2-β1) 2 +(γ2-γ1) 2 ] 1 / 2 (6).

[0046] Furthermore, in the configuration described in one embodiment of the present invention, the following formula (5) may also be satisfied in the planar portion adjacent to at least one of the curved portions.

[0047] Φ 3D ave: 2.0°~4.0° (5)

[0048] Here, Φ 3D ave satisfies Φ 3D Φ at grain boundary criterion point ≥1.0° 3D The average value.

[0049] Invention Effects

[0050] According to the present invention, in a wound iron core formed by stacking layers of bent steel plates, the deterioration of iron core efficiency accompanying the bending process can be effectively suppressed. Attached Figure Description

[0051] Figure 1 This is a perspective view schematically illustrating one embodiment of the wound iron core involved in the present invention.

[0052] Figure 2 yes Figure 1 The side view of the wound iron core shown in the embodiment.

[0053] Figure 3 This is a side view schematically illustrating another embodiment of the wound iron core involved in the present invention.

[0054] Figure 4 This is a side view schematically showing an example of a single layer of directional electromagnetic steel sheet constituting the wound iron core of the present invention.

[0055] Figure 5 This is a side view schematically showing another example of a single layer of directional electromagnetic steel sheet constituting the wound iron core of the present invention.

[0056] Figure 6 This is a side view schematically showing an example of a curved portion of the directional electromagnetic steel sheet constituting the wound iron core of the present invention.

[0057] Figure 7 This is a diagram used to schematically illustrate the offset angle associated with the crystal orientation observed in a directional electromagnet.

[0058] Figure 8 This is a schematic diagram illustrating a method for determining grain boundary points by arranging multiple measurement points in a planar region adjacent to a curved portion and measuring two adjacent measurement points.

[0059] Figure 9 This is a schematic diagram showing the dimensional parameters of the wound iron core manufactured according to the embodiments and comparative examples. Detailed Implementation

[0060] The wound iron core according to one embodiment of the present invention will now be described in detail. However, the present invention is not limited to the configuration disclosed in this embodiment, and various modifications can be made without departing from the spirit of the present invention. Furthermore, in the numerical ranges described below, the lower and upper limits are included within the range. Values ​​expressed as "more than" or "less than" are not included in the numerical range. In addition, the "%" in relation to chemical composition means "mass %" unless otherwise specified.

[0061] Furthermore, the terms such as “parallel,” “perpendicular,” “same,” “right angle,” etc., used in particular in this specification, or the values ​​of length, angle, etc., are not limited to a strict meaning, but are interpreted to include a range of degrees to which the same function can be expected.

[0062] In addition, in this specification, "directional electromagnetic steel plate" is sometimes simplified to "steel plate" or "electromagnetic steel plate", and "wound iron core" is simplified to "iron core".

[0063] This embodiment relates to a wound iron core, which is a wound iron core body that is generally polygonal in shape when viewed from the side. The wound iron core is characterized in that:

[0064] The wound core body comprises a portion formed by stacking directional electromagnetic steel plates in the thickness direction, with alternating planar portions and curved portions in the length direction, and has a stacked structure that appears roughly polygonal in side view.

[0065] The inner side curvature radius r of the curved portion in the side view is more than 1 mm and less than 5 mm;

[0066] The directional electromagnetic steel sheet has a chemical composition of 2.0 to 7.0% by mass, with the remainder being Fe and impurities, and has a texture oriented toward the Goss orientation; and in one or more of the planar portions adjacent to at least one curved portion, the following formulas (1) to (4) are satisfied.

[0067] 0.10≤Nt / Nx≤0.80 (1)

[0068] 0.37≤Nb / Nt≤0.80 (2)

[0069] 1.07≤Nb / Na≤4.00 (3)

[0070] Nb / Nc≥1.10 (4)

[0071] Here, Nx in the formula (1) is: when multiple measuring points are arranged at 5mm intervals in the region of the planar part adjacent to the curved part in the direction parallel to the boundary of the curved part and the planar part, i.e. the boundary of the curved part, in the parallel direction, the total number of grain boundary determination points that exist in the center of two adjacent measuring points in the parallel direction for determining whether there is a grain boundary between the two measuring points.

[0072] Furthermore, regarding the crystal orientation observed in directional electromagnetic steel sheets,

[0073] The offset angle from the ideal Goss orientation, with the normal direction Z of the rolled surface as the axis of rotation, is defined as α.

[0074] The offset angle from the ideal Goss orientation, with the rolling right-angle direction C as the rotation axis, is defined as β.

[0075] The offset angle from the ideal Goss orientation with the rolling direction L as the rotation axis is defined as γ.

[0076] When the offset angles of the crystal orientation measured at the two measurement points are expressed as (α1,β1,γ1) and (α2,β2,γ2), the angle Φ obtained by the following equation (6) is... 3D When defining the three-dimensional orientation difference of offset angles α, β, and γ,

[0077] In equations (1) and (2), Nt is: satisfying Φ 3D The number of grain boundary criteria points ≥1.0°

[0078] In equation (3), Na is: satisfying Φ 3D The number of grain boundary criteria points with a gradient greater than 1.0° and less than 2.5°.

[0079] In equations (2) and (3), Nb is: satisfying Φ 3D The number of grain boundary criteria points with a gradient greater than 2.5° and less than 4.0°.

[0080] In equation (4), Nc is: Φ 3D The number of grain boundary determination points above 4.0°;

[0081] Φ 3D =[(α2-α1) 2 +(β2-β1) 2 +(γ2-γ1) 2 ] 1 / 2 (6).

[0082] 1. Shape of the wound iron core and directional electromagnetic steel sheet

[0083] First, the shape of the wound iron core in this embodiment will be described. The shapes of the wound iron core and the directional electromagnetic steel plate described here are not particularly novel. For example, they are simply referenced to the shapes of the wound iron core and the directional electromagnetic steel plate known in the background art as described in Patent Documents 5 to 7.

[0084] Figure 1 This is a perspective view schematically illustrating one embodiment of a wound iron core. Figure 2 yes Figure 1 A side view of the wound iron core shown in the embodiment. Furthermore, Figure 3 This is a side view schematically illustrating another embodiment of the wound iron core.

[0085] Furthermore, in this embodiment, the term "side view" refers to the view along the width of the elongated directional electromagnetic steel plate constituting the wound core. Figure 1 Looking at the Y-axis direction (in the diagram), a side view is a diagram that shows the shape as seen from the side. Figure 1 (Graph of the Y-axis direction).

[0086] The wound core according to this embodiment has a wound core body 10 that is generally polygonal (generally rectangular) in side view. The wound core body 10 is formed by stacking directional electromagnetic steel plates 1 in the thickness direction, and has a stacked structure 2 that is generally rectangular in side view. The wound core body 10 can also be used directly as a wound core. In order to fix the stacked multiple directional electromagnetic steel plates 1 as a whole, known fasteners such as cable ties can also be provided as needed.

[0087] In this embodiment, the length of the core of the wound core body 10 is not particularly limited. Even if the core length varies, the iron loss occurring in the bending portion 5 is fixed because the volume of the bending portion 5 is constant. Since a longer core length reduces the volume ratio of the bending portion 5 relative to the wound core body 10, the impact on iron loss degradation is also smaller. Therefore, a longer core length of the wound core body 10 is preferable. Preferably, the core length of the wound core body 10 is 1.5 m or more, more preferably 1.7 m or more. Furthermore, in this embodiment, the core length of the wound core body 10 refers to the circumference at the center point in the stacking direction of the wound core body 10 when viewed from the side.

[0088] The wound core of this embodiment is suitable for any application known in the past.

[0089] The core of this embodiment is characterized by being approximately polygonal in side view. In the following description using the accompanying drawings, for the sake of simplicity, a generally rectangular (quadrilateral) core is used. However, the angle and number of bends and the length of the flat sections can be appropriately varied, thereby allowing the manufacture of cores of various shapes. For example, if all bends have an angle of 45° and the lengths of the flat sections are equal, it appears as an octagon in side view. Furthermore, if it has six bends with an angle of 60° and the lengths of the flat sections are equal, it appears as a hexagon in side view.

[0090] like Figure 1 and Figure 2 As shown, the wound core body 10 includes a portion formed by stacking directional electromagnetic steel plates 1, which are alternately continuous in the thickness direction by planar portions 4 and curved portions 5 in the length direction, and has a stacked structure 2 that is approximately rectangular in shape when viewed from the side. In the side view of the wound core body 10, the planar portions 4 have two types: four planar portions 4a whose circumferential length is longer than that of the planar portions 4b, and four planar portions 4b whose circumferential length is shorter than that of the planar portions 4a. However, the lengths of the planar portions 4a and 4b can also be equal.

[0091] In addition, Figure 3In the shown wound core body 10, the planar portion 4 has two types of planar portions in the side view of the wound core body 10: four planar portions 4a with a longer circumferential length and eight planar portions 4b with a shorter circumferential length.

[0092] Figure 2 In one embodiment, the bending portion 5 is 45°. Figure 3 In one embodiment, the bend 5 is 30°. That is, in any embodiment, the total bend angle of each bend present in a corner 3 is 90°.

[0093] In addition, the main body 10 of the wound iron core has 4 corner sections 3. Figure 2 Each corner portion 3 of the wound iron core body 10 shown has a flat portion 4b and two curved portions 5 connected to its two ends. Figure 3 The corner portions 3 of the wound core body 10 shown have: two adjacent flat portions 4b, 4b; a curved portion 5 provided between and connected to the flat portions 4b, 4b; and curved portions 5 respectively connected to the ends of the two flat portions 4b, 4b. That is, Figure 2 One implementation is that there are two curved portions 5 in one corner portion 3. Figure 3 One implementation is that there are three curved parts 5 in one corner part 3.

[0094] Furthermore, in the following description, either plane part 4a or plane part 4b will be described as plane part 4.

[0095] As these examples illustrate, the core of this embodiment can be constructed from bends with various angles. From the perspective of suppressing iron loss by suppressing the occurrence of strain caused by deformation during processing, it is preferable that the bending angle Φ (Φ1, Φ2, Φ3) of the bend 5 is 60° or less, and more preferably 45° or less.

[0096] The bending angle Φ of the bent portion of an iron core can be arbitrarily configured. For example, it can be specified that Φ1=60° and Φ2=30°, but it is preferable that the bending angles are equal from the perspective of production efficiency.

[0097] Reference Figure 6 A more detailed explanation of the curved section 5 will follow. Figure 6This is a schematic illustration of an example of a curved portion (curved section) of a directional electromagnetic steel sheet. The bending angle of the curved portion refers to the angle difference between the straight section on the rear side and the straight section on the front side of the curved portion 5 in the bending direction of the directional electromagnetic steel sheet 1. It is represented by the supplementary angle Φ formed by extending the straight sections of the flat sections 4 (4a, 4b) sandwiching the two sides of the curved portion 5 on the outside of the directional electromagnetic steel sheet 1. The point where the extended straight line leaves the surface of the steel sheet is the boundary between the flat sections 4 (4a, 4b) on the outer surface of the steel sheet and the curved portion 5. Figure 6 In the middle, points F and G are points F and G respectively.

[0098] Furthermore, straight lines perpendicular to the outer surface of the steel plate are extended from points F and G respectively, and their intersections with the inner surface of the steel plate are designated as points E and D. These points E and D are the boundaries between the planar portion 4 (4a, 4b) and the curved portion 5 on the inner surface of the steel plate.

[0099] Furthermore, in this embodiment, the so-called curved portion 5 refers to the portion of the directional electromagnetic steel plate 1 that is surrounded by the aforementioned points D, E, F, and G in a side view of the directional electromagnetic steel plate 1. Figure 6 In the diagram, La represents the inner surface of the steel plate between points D and E, i.e., the curved section 5, and Lb represents the outer surface of the steel plate between points F and G, i.e., the curved section 5.

[0100] also, Figure 6 The inner surface curvature radius r (hereinafter referred to as curvature radius r) of the curved portion 5 in the side view is shown in the figure. The curvature radius r of the curved portion 5 is obtained by approximating La with an arc passing through points E and D. The smaller the curvature radius r, the greater the curvature of the curved portion of the curved portion 5; the larger the curvature radius r, the less curvature of the curved portion of the curved portion 5.

[0101] In the wound core of this embodiment, the radius of curvature r in each bent portion 5 of each directional electromagnetic steel plate 1 stacked in the thickness direction may vary to some extent. This variation sometimes arises from variations in forming accuracy, and can be considered as an unintentional change due to processing during stacking, etc. Such unintentional errors can be controlled to around 0.2 mm or less in typical industrial manufacturing. In cases of large variations, a representative value can be obtained by measuring the radius of curvature r of a sufficient number of steel plates and averaging the measured values. Furthermore, it is also possible to intentionally change it for some reason; this embodiment does not exclude such a possibility.

[0102] Furthermore, there are no particular limitations on the method for measuring the radius of curvature r of the inner side of the curved portion 5. For example, a commercially available microscope (Nikon ECLIPSE LV150) can be used to measure it by observation at 200x magnification. Specifically, the result is determined from the observation. Figure 6 The curvature center point A is shown as described. However, as a calculation method, for example, if line segments EF and DG are extended to the inner side opposite to point B, and their intersection is taken as A, then the size of the inner side curvature radius r is equivalent to the length of line segment AC. Here, when connecting points A and B with a straight line, the intersection with the arc DE on the inner side of the curved part 5 is taken as point C.

[0103] In this embodiment, by setting the radius of curvature r of the bent portion 5 to a range of 1 mm or more and 5 mm or less, and by using a specific directional electromagnetic steel plate controlled in a manner where grain boundaries with large differences in crystal orientation exist at a higher frequency (as described below), the efficiency of the core can be specified to be the optimal efficiency commensurate with its magnetic properties. Preferably, the radius of curvature r of the inner side of the bent portion 5 is 3 mm or less. In this case, the effects of this embodiment can be more significantly achieved.

[0104] Furthermore, it is most preferred that all the bends within the core satisfy the inner surface curvature radius r specified in this embodiment. When there are bends in the wound core that satisfy the inner surface curvature radius r of this embodiment and bends that do not, it is preferable that at least half of the bends satisfy the inner surface curvature radius r specified in this embodiment.

[0105] Figure 4 and Figure 5 This is a schematic illustration of an example of a layer of directional electromagnetic steel plate 1 wound in the main body 10 of the iron core. (See diagram below.) Figure 4 and Figure 5 As shown in the example, the directional electromagnetic steel plate 1 used in this embodiment is formed by bending and has a corner portion 3 and a flat portion 4 containing two or more bends 5. It forms a ring that is generally polygonal in side view through one or more end faces, i.e., joint portions 6, in the longitudinal direction of the directional electromagnetic steel plate 1.

[0106] In this embodiment, the wound core body 10 only needs to have a generally polygonal layered structure 2 when viewed from the side. For example... Figure 4 As shown in the example, a single coiled core body 10 can also be formed from a single directional electromagnetic steel plate 1 via a joint 6 (that is, each coil is connected to a single directional electromagnetic steel plate 1 via a joint 6), as... Figure 5As shown in the example, a wound core of about half a turn can also be formed by one directional electromagnetic steel plate 1, and a wound core body 10 can be formed by two directional electromagnetic steel plates 1 via two joints 6 (that is, each roll connects two directional electromagnetic steel plates 1 to each other via two joints 6).

[0107] The thickness of the directional electromagnetic steel plate 1 used in this embodiment is not particularly limited and can be appropriately selected according to the application, but it is usually in the range of 0.15mm to 0.35mm, preferably in the range of 0.18mm to 0.23mm.

[0108] 2. Composition of Directional Electromagnetic Steel Sheets

[0109] Next, the structure of the directional electromagnetic steel plate 1 constituting the main body 10 of the wound iron core will be described. In this embodiment, the width direction of the directional electromagnetic steel plate 1 in the planar portion 4 (4a, 4b) adjacent to the bent portion 5 of the adjacently stacked electromagnetic steel plates 1 will be described. Figure 8 The control of crystal orientation variation (the extension direction of the boundary line B shown) and the configuration of the controlled electromagnetic steel plate within the iron core are used as features.

[0110] (1) Changes in crystal orientation of the planar portion adjacent to the curved portion

[0111] The directional electromagnetic steel plate 1 constituting the wound core of this embodiment is controlled such that, at least in a portion of the region near the bend 5, the crystal orientation of the stacked steel plates 1 is appropriately varied in a direction parallel to the boundary (width direction of the directional electromagnetic steel plate) of the bend 5 and its adjacent planar portions 4 (4a, 4b) (hereinafter also referred to as the bend boundary). If the variation in crystal orientation near the bend decreases, the effect of avoiding efficiency degradation in a core with a core shape as described in this embodiment will not be exhibited. In other words, it means that efficiency degradation is easily suppressed by arranging grain boundaries with large orientation changes near the bend 5.

[0112] The mechanism behind this phenomenon is not entirely clear, but it can be considered as follows.

[0113] In this embodiment, the macroscopic strain (deformation) of the core caused by bending is confined to a very narrow region, namely within the bending portion 5. However, considering the internal crystal structure of the steel plate, it can be assumed that the micro-strain moves and extends outward from the bending portion 5, i.e., to the planar portions (4a, 4b). In particular, in the surface layer of the steel plate outside the core where the tensile deformation in the rolling direction of the directional electromagnetic steel plate is significant, the effect of strain towards the planar portions 4 (4a, 4b) expands, and twinning deformation also occurs in the planar portions 4 (4a, 4b) near the bending portion 5. It is known that twinning deformation formed by ordinary processing significantly deteriorates iron loss. Therefore, iron loss deterioration can be suppressed by avoiding the occurrence of twins in the bending portion. Furthermore, not limited to avoiding the number of twins, considering the above situation, it is also important to suppress the expansion of the twinning region towards the planar portion region 4 (4a, 4b) to suppress iron loss deterioration. It can be assumed that one of the reasons for the occurrence of twins is the limitation of the crystallization deformation, i.e., the slip system. Therefore, it can be considered that the twinning region is expanded by restricting the deformation state to a uniform deformation state with very small orientation dispersion of grain boundary grains near the bend 5. Conversely, if the orientation dispersion of grain boundary grains near the bend 5 is moderately large, the deformation behavior becomes more complex, which can mitigate the restricted uniform deformation state, and thus it is expected to reduce the deformation region, i.e., the twinning region. This embodiment believes that the decrease in core efficiency can be suppressed through this effect. Such a mechanism of action in this embodiment can be considered as a special phenomenon in the core with a specific shape that is the object of this embodiment, which has been almost overlooked until now, but can be interpreted as being consistent with the insights obtained by the inventors.

[0114] In this embodiment, the change in crystal orientation can be measured as follows.

[0115] In this embodiment, the following four angles α, β, γ, and Φ, which are related to the crystal orientation observed in the directional electromagnetic steel plate 1, are used. 3D Furthermore, as will be discussed later, angle α means rotation about the direction Z, the normal to the rolled surface, from the ideal {110} <001> The offset angle of the orientation (Goss orientation), angle β, means the rotation axis about the rolling right-angle direction (plate width direction) C from the ideal {110} <001> The orientation offset angle, angle γ, means the rotation about the rolling direction L as the axis of rotation from the ideal {110} <001> The offset angle of orientation.

[0116] Here, the so-called "ideal {110}" <001> "Orientation" does not refer to the crystal orientation of a practical steel sheet {110} <001> Orientation, but rather as an academic crystal orientation {110} <001> orientation.

[0117] Generally, in determining the crystal orientation of recrystallized practical steel sheets, the crystal orientation is specified in a way that does not strictly distinguish between angle differences of approximately ±2.5°. For conventional directional electromagnetic steel sheets, however, the orientation is specified using a geometrically strict {110}... <001> The angular range of approximately ±2.5° centered on the orientation is designated as "{110}". <001> "Orientation". However, in this embodiment, it is also necessary to clearly distinguish angle differences below ±2.5°.

[0118] Therefore, regarding {110} as a geometrically strict crystal orientation <001> In this embodiment, the orientation is specified to avoid the use of {110} in previously known documents, etc. <001> The confusion of orientations is recorded as "ideal {110}". <001> Orientation (ideal Goss orientation)".

[0119] Offset angle α: The crystal orientation observed in the directional electromagnetic steel sheet 1, around the rolling surface normal direction Z, from the ideal {110} <001> The offset angle of orientation.

[0120] Offset angle β: The crystal orientation observed in the directional electromagnetic steel sheet 1, around the rolling right-angle direction C, from the ideal {110} <001> The offset angle of orientation.

[0121] Offset angle γ: The crystal orientation observed in the directional electromagnetic steel sheet 1 around the rolling direction L from the ideal {110} <001> The offset angle of orientation.

[0122] Figure 7 The diagram shows the aforementioned offset angles α, β, and γ.

[0123] Angle Φ 3D When the aforementioned offset angles of crystal orientation measured at two adjacent measurement points spaced 5 mm apart on the rolled surface of the directional electromagnetic steel sheet are expressed as (α1,β1,γ1) and (α2,β2,γ2), respectively, it is through Φ 3D =[(α2-α1) 2 +(β2-β1) 2 +(γ2-γ1) 2 ] 1 / 2 And the angle obtained.

[0124] Sometimes this angle Φ 3D It is recorded as "spatial three-dimensional orientation difference".

[0125] Currently, the crystal orientation of directional electromagnetic steel sheets used in practical manufacturing is determined by the rolling direction and <001> The directional offset angle is controlled to be approximately 5° or less. This control is also applied to the directional electromagnetic steel sheet 1 described in this embodiment. Therefore, when defining the "grain boundary" of the directional electromagnetic steel sheet, the general definition of a grain boundary (large-angle grain boundary), i.e., "a boundary where the orientation difference between adjacent regions is 15° or more," cannot be applied. For example, in conventional directional electromagnetic steel sheets, grain boundaries are revealed by macroscopic corrosion of the steel sheet surface, but the average crystal orientation difference between the regions on both sides of the grain boundary is in the range of 2 to 3°.

[0126] As will be described later, this implementation method requires strict definition of the boundaries between crystals. Therefore, as a specific method for grain boundaries, visual methods such as macroscopic etching are not employed.

[0127] In this embodiment, to determine specific grain boundaries, measurement points are set at 5mm intervals on the rolled surface of the directional electromagnetic steel sheet 1, and the crystal orientation is measured at each measurement point. For example, the crystal orientation can be determined simply by X-ray diffraction (Laué method). The Laué method is a method of analyzing the transmitted or reflected diffraction spots by irradiating the steel sheet with an X-ray beam. By analyzing the diffraction spots, the crystal orientation at the irradiated location can be identified. By changing the irradiation position and analyzing the diffraction spots at multiple locations, the crystal orientation distribution at each irradiation location can be determined. The Laué method is suitable for determining the crystal orientation of metal structures with coarse grains.

[0128] like Figure 8 As shown, in this embodiment, within the area of ​​the planar portion 4 (4a, 4b) adjacent to the curved portion 5, a straight line SL is set parallel to the extending direction of boundary B at a position 2 mm vertically from the boundary B (the boundary of the curved portion) that is approximately straight from the boundary of the curved portion 5 and the planar portion 4 (4a, 4b). Furthermore, measurement points are arranged at 5 mm intervals along the straight line SL within this planar portion 4 (4a, 4b) in a direction parallel to the boundary (line) B. At this time, the same number of measurement points are arranged on both sides, starting from the center of the straight line SL (the center of the width direction of the steel plate). However, when the measurement points at both ends of the straight line SL are close to the ends of the steel plate in the width direction, the error in orientation measurement increases, and it is easy to become abnormal data. Therefore, measurement points near these ends should be avoided during measurement.

[0129] The reason for specifying a 2mm distance between the measurement point (straight line SL) and the boundary (line) B is that, compared to this, twinning occurs in the steel plate surface layer in the region closer to the bend 5, raising concerns about potential deviations in the measurement of crystal orientation variations. On the other hand, the possibility of measuring grain orientations different from the crystal orientation of the bend that directly affects the strain propagation of the bend 5 increases in regions separated by this distance. In other words, the distance between the straight line SL and the boundary B does not necessarily need to be 2mm. However, when setting the straight line SL at a distance greater than 2mm, it is necessary to consider that its setting position enters a region where the crystal orientation affecting the strain propagation of the bend 5 can be measured.

[0130] Furthermore, for each measurement point, the aforementioned offset angles α, β, and γ are specified. Based on each offset angle at each specified measurement point, it is determined whether a grain boundary exists between two adjacent measurement points. In this embodiment, the concept of a "grain boundary determination point" (hereinafter also referred to as a grain boundary point) is defined to determine whether there is a boundary (grain boundary) between two measurement points that exists at the center of the two measurement points and is determined by the orientation difference between the two measurement points.

[0131] Specifically, the aforementioned angle Φ at two adjacent measurement points 3D When Φ ≥ 1.0°, it is determined that a grain boundary exists in the center between the two points. That is to say, orientation variations below 1.0° are ignored as orientation variations that do not contribute to the effectiveness of the present invention or are merely measurement errors.

[0132] Φ 3D Grain boundaries with an angle of 2° or greater are roughly equivalent to grain boundaries of previously recrystallized grains as understood through macroscopic corrosion. In typical directional electromagnetic steel sheets, the orientation difference between two points sandwiched between grain boundaries, as described above, averages around 2–3°. Therefore, in this embodiment, even small orientation differences not generally recognized as grain boundaries are considered. Furthermore, in typical directional electromagnetic steel sheets, a Φ... 3D Grain boundaries exceeding 3° are evaluated.

[0133] First, Φ was measured 3D Let the total number of grain boundary points be Nx, where Φ will satisfy... 3D The number of grain boundary points ≥1.0° is set as Nt. In this embodiment, as described above, in the region of the planar portion 4 (4a, 4b) adjacent to the curved portion 5, the same number of measuring points are arranged at equal intervals in a direction parallel to the boundary line B, and with the position about the width of the steel plate starting from the center of the steel plate width on both sides. Moreover, a grain boundary point is defined between two adjacent measuring points, and the Φ at the grain boundary point is determined. 3DAdditionally, regarding grain boundary points, they are set to Nt = 60 or higher. When Nt is less than 60 points in a single steel sheet, for example, when the steel sheet is narrow or Φ... 3D When the proportion of grain boundary points below 1.0° increases, measurements are performed on multiple steel plates. Additionally, when satisfying Φ... 3D The number of grain boundary points with an angle greater than 1.0° and less than 2.5° is set as Na, and the condition Φ is satisfied. 3D The number of grain boundary points with an angle greater than 2.5° and less than 4.0° is defined as Nb, and Φ is defined as... 3D The number of grain boundary points exceeding 4.0° is defined as Nc. Additionally, the condition Φ is... 3D Φ of grain boundary points ≥1.0° 3D Let the average value be Φ 3D ave.

[0134] The directional electromagnetic steel plate 1 described in this embodiment effectively suppresses the occurrence of twins near the curved portion 5 and the expansion of the twinning region into the planar regions 4 (4a, 4b) by having grain boundaries with large differences in crystal orientation present at a relatively high frequency. As a result, the core efficiency can be improved.

[0135] In one embodiment of the wound iron core involved in this embodiment, the following formulas (1) to (4) are satisfied in the planar portion 4 (4a, 4b) near at least one bent portion 5 of the stacked arbitrary directional electromagnetic steel plate 1.

[0136] 0.10≤Nt / Nx≤0.80 (1)

[0137] 0.37≤Nb / Nt≤0.80 (2)

[0138] 1.07≤Nb / Na≤4.00 (3)

[0139] Nb / Nc≥1.10 (4)

[0140] This provision indicates that one side is limited to satisfying Φ. 3D The presence rate of grain boundaries is 1.0° or higher. In the planar portion 4 (4a, 4b) near the curved portion 5, the main grain boundaries should be those with a strong inhibitory effect on twinning.

[0141] Regarding formula (1), since the interval between the measurement points is set to 5 mm, it indicates that at least one grain boundary exists in a region with an average interval of approximately 50 mm or less, i.e., an average interval of approximately 50 mm. Since the presence of grain boundaries can also bring about the effect of this embodiment, if the frequency of grain boundary presence is too low, the effect will not be observed. Preferably, Nt / Nx is 0.13 or more (as an average interval of approximately 38 mm or less), more preferably 0.20 or more (as an average interval of approximately 25 mm or less). On the other hand, a large ratio means fine particle size, which also causes a decrease in magnetic properties, so the upper limit of Nt / Nx is specified as 0.80 or less (as an average interval of approximately 6 mm or more).

[0142] Equation (2) indicates that the frequency of grain boundaries with large angle differences is high, resulting in a significant twinning suppression effect. Generally speaking, crystal orientation control in directional electromagnetic steel sheets aims to increase the aggregation degree towards the Goss orientation, reduce the angle difference of grain boundaries, and ultimately achieve single crystallization. Considering this situation, the provision in this embodiment, which controls the presence frequency of grain boundaries with relatively large angle differences to a high level, can be considered special. However, since a high presence frequency of Nb also involves a low aggregation degree towards the Goss orientation, excessive increase should be avoided. Preferably, Nb / Nt is 0.40 to 0.70, more preferably 0.45 to 0.65.

[0143] Equation (3) specifies the frequency of grain boundaries with large angle differences that significantly suppress twinning, as defined in Equation (2), based on the ratio of the frequency of grain boundaries with small angle differences that have low twinning suppression effect to the frequency of grain boundaries with small angle differences. Preferably, Nb / Na is 1.4 or more, and more preferably 1.7 or more.

[0144] Equation (4) is a rule used to avoid the occurrence of grain boundaries with excessively large angle differences, as the formation of these boundaries significantly reduces the aggregation towards the Goss orientation, leading to a decrease in magnetic properties. Preferably, Nb / Nc is 2.0 or more, more preferably 3.0 or more. Furthermore, of course, in all the planar portions adjacent to the bends present in the wound core, it is preferable to satisfy all of the above equations (1) to (3).

[0145] As another embodiment, the following formula (5) is further satisfied in the planar portion near at least one curved portion of the stacked arbitrary directional electromagnetic steel plate.

[0146] Φ 3D ave: 2.0°~4.0° (5)

[0147] This specification is a specification that simply evaluates the magnitude of the change in crystal orientation. Furthermore, this specification, under the premise of satisfying the above formulas (1) to (4), represents the appropriate average value of the angle difference of the crystal orientation between the grain boundaries, corresponding to one of the preferred methods of this embodiment, while achieving the effects of this embodiment. That is, by using Φ 3D The ave is specified as 2.0° to 4.0°, which can effectively suppress twinning in the planar region. Regarding Φ... 3D The ave is preferably 2.5° to 3.5°. Furthermore, it is of course preferred that Φ be the angle of all planar portions adjacent to the bend in the wound core. 3D The ave is 2.0° to 4.0°.

[0148] (2) Directional electromagnetic steel plate

[0149] As described above, in the directional electromagnetic steel sheet 1 used in this embodiment, the mother steel sheet is a mother steel sheet in which the grains are highly oriented and clustered in {110}. <001> Oriented steel sheets are steel sheets that have excellent magnetic properties in the rolling direction.

[0150] In this embodiment, a known directional electromagnetic steel sheet can be used as the mother steel plate. Hereinafter, an example of a preferred mother steel plate will be described.

[0151] The chemical composition of the mother steel plate, by mass%, contains 2.0%–6.0% Si, with the remainder consisting of Fe and impurities. This chemical composition is used to control the crystal orientation, focusing on the aggregation of crystals in {110}. <001> The oriented Goss texture ensures good magnetic properties. There are no particular limitations regarding other elements, but in this embodiment, in addition to Si, Fe, and impurities, other elements may be included within a range that does not impair the effects of the invention. For example, it is permissible to include the following elements within the range by substituting a portion of Fe. Representative selections of these elements are described below.

[0152] C: 0~0.0050%

[0153] Mn: 0~1.0%,

[0154] S: 0~0.0150%,

[0155] Se: 0~0.0150%,

[0156] Al: 0~0.0650%

[0157] N: 0~0.0050%

[0158] Cu: 0–0.40%

[0159] Bi: 0~0.010%,

[0160] B: 0~0.080%,

[0161] P: 0–0.50%,

[0162] Ti: 0~0.0150%,

[0163] Sn: 0~0.10%,

[0164] Sb: 0~0.10%,

[0165] Cr: 0~0.30%

[0166] Ni: 0~1.0%,

[0167] Nb: 0~0.030%,

[0168] V: 0~0.030%,

[0169] Mo: 0–0.030%

[0170] Ta: 0~0.030%,

[0171] W: 0~0.030%.

[0172] Since these selected elements only need to be present according to their purpose, their lower limit value does not need to be limited, and they can be substantially absent. Furthermore, even if these selected elements are present as impurities, it does not impair the effect of this embodiment. Moreover, it is difficult to specify a C content of 0% in practical steel plates during manufacturing; therefore, the C content can be specified to be greater than 0%. Furthermore, "impurity" refers to elements that are unintentionally present, meaning elements that are mixed in from the ore, waste, or manufacturing environment used as raw materials during the industrial manufacture of the mother steel plate. The upper limit of the total impurity content can be, for example, 5%.

[0173] The chemical composition of the base steel plate can be determined using general analytical methods for steel. For example, the chemical composition of the base steel plate can be determined using ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectrometry). Specifically, for example, a 35mm square test piece can be obtained from the center of the base steel plate after the covering film has been removed, and the composition can be determined using a Shimadzu ICPS-8100 (measuring device) under conditions based on a pre-prepared calibration curve. Furthermore, C and S can be determined using the combustion-infrared absorption method, and N can be determined using the inert gas melting-thermal conductivity method.

[0174] Furthermore, the aforementioned chemical composition refers to the composition of the directional electromagnetic steel plate 1, which serves as the mother steel plate. When the directional electromagnetic steel plate 1, which serves as the test sample, has a primary coating film (glass coating film, intermediate layer), an insulating coating film, etc., formed from oxides or the like on its surface, the chemical composition is determined after these films are removed using known methods.

[0175] (3) Manufacturing method of directional electromagnetic steel sheet

[0176] There are no particular limitations on the manufacturing method of directional electromagnetic steel sheets. As described later, by strictly controlling the manufacturing conditions, the frequency of grain boundaries with large orientation changes can be increased. By using directional electromagnetic steel sheets with such grain boundaries and manufacturing a wound core according to suitable processing conditions described later, a wound core that can effectively suppress the deterioration of core efficiency can be obtained. As a preferred specific example of the manufacturing method, for example, firstly, a slab with the above-mentioned chemical composition of directional electromagnetic steel sheets, wherein C is specified as 0.04 to 0.1% by mass, is heated to above 1000°C and hot-rolled, and then wound at 400 to 850°C. The hot-rolled sheet is then annealed as needed. Although there are no particular limitations on the annealing conditions of the hot-rolled sheet, from the viewpoint of controlling precipitates, it is preferable to specify an annealing temperature of 800 to 1200°C and an annealing time of 10 to 1000 seconds. Next, a cold-rolled steel sheet is obtained by cold rolling once or twice or more with intermediate annealing. From the perspective of controlling texture, the cold rolling yield at this stage is preferably specified as 80-99%. The cold-rolled steel sheet is then decarburized and annealed, for example, in a moist hydrogen-inert gas atmosphere to 700-900°C, and further nitrided if necessary. From the perspective of controlling precipitates and texture, the higher the plate tension and nitriding amount during nitriding annealing, the better. Specifically, it is preferable to set the plate tension to 3.0 (N / mm). 2 The nitriding amount is preferably set to 240 ppm or higher. Then, after applying an annealing release agent to the annealed steel sheet, final annealing is performed at a maximum reaching temperature of 1000℃~1200℃ for 40~90 hours, forming an insulating coating film at approximately 900℃. Finally, coatings for adjusting the coefficient of friction may also be applied. Among the above conditions, the nitriding amount and plate tension, in particular, affect the variation in crystal orientation. Therefore, when manufacturing the wound core, it is preferable to use directional electromagnetic steel sheets manufactured within the above-mentioned conditions.

[0177] Furthermore, even steel sheets that have undergone a process known as "magnetic domain control" during the steel sheet manufacturing process can generally enjoy the effects of this embodiment.

[0178] As described above, the characteristic of the directional electromagnetic steel sheet 1 used in this embodiment, namely the grain boundaries with large angle differences, can be achieved, for example, by the following method. In this method, a portion of the manufacturing conditions of known directional electromagnetic steel sheets, which are manufactured in a manner that increases the aggregation degree toward the Goss orientation to the limit (i.e., manufactured in a manner that reduces the angle of the grain boundaries to the limit), are removed from the optimal conditions. Specifically, by adjusting the arrival temperature and residence time of the final annealing, the growth until the limit of the Goss orientation is stopped, leaving grains with a residual orientation slightly deviating from the Goss orientation. Furthermore, the final annealing is not the only limitation; the chemical composition of the slab, hot rolling conditions, decarburizing annealing conditions, nitriding conditions, annealing separation agent coating conditions, etc., are not particularly limited, but it is preferable to suppress the increase in the aggregation degree toward the Goss orientation by appropriately adjusting various processes and conditions. In this way, by increasing the formation frequency of grain boundaries with large angle differences in advance throughout the steel sheet, even when the bend 5 is formed at any position during the manufacturing of the wound core, it is expected that the above-mentioned conditions can be satisfied in the wound core. Alternatively, to manufacture a wound core with a greater number of grain boundaries with large angle differences near the bend 5, controlling the bending position of the steel sheet by placing regions with a higher frequency of grain boundaries with large angle differences near the bend 5 is also effective. In this method, during the manufacturing of the steel sheet, based on known methods such as locally modifying the primary recrystallization structure, nitriding conditions, and the state of the annealing separating agent coating, it is also possible to manufacture a steel sheet with locally modified secondary recrystallization grain growth, and select the region with a higher frequency of grain boundaries with large angle differences for bending processing.

[0179] 3. Manufacturing method of wound iron core

[0180] The method for manufacturing the wound iron core according to this embodiment is not particularly limited as long as it can manufacture the wound iron core according to this embodiment. For example, it can be applied to the method based on the known wound iron core described in Patent Documents 5 to 7 in the background art. In particular, it can be said that the method using the UNICORE (https: / / www.aemcores.com.au / technology / unicore / ) manufacturing apparatus of AEM UNICORE Corporation is most suitable.

[0181] Furthermore, from the viewpoint of increasing the frequency of grain boundaries with large angle differences near the bend 5, it is preferable to control the conditions during core machining. For example, this can be achieved by controlling the machining speed (piercing speed, mm / s) and the temperature rise of the steel plate caused by machining heat, ΔT (°C). Specifically, it is preferable to specify the piercing speed as 20 to 100 (mm / s). In addition, when the temperature rise of the steel plate caused by machining heat is set as ΔT, it is preferable to control ΔT to be below 5.0°C.

[0182] Alternatively, heat treatment can be performed as needed using known methods. Furthermore, the resulting wound core body 10 can be used directly as a wound core, but it can also be further used, as needed, to integrally fix the stacked multiple directional electromagnetic steel plates 1 with known fasteners such as strapping straps, thereby forming a wound core.

[0183] This embodiment is not limited to the above-described embodiment. The above-described embodiment is an example, and any structure having substantially the same technical concept as that described in the claims of this invention, and achieving the same effect, is included within the technical scope of this invention.

[0184] Example

[0185] The technical content of the present invention will be further described below while listing embodiments. The conditions in the embodiments shown below are examples of conditions adopted to confirm the feasibility and effects of the present invention, and the present invention is not limited to these examples. Furthermore, various conditions can be adopted as long as they do not depart from the spirit of the present invention and achieve the purpose of the present invention.

[0186] (Directional electromagnetic steel sheet)

[0187] Using slabs with the chemical composition shown in Table 1 (mass %, the remainder other than indicated is Fe) as raw materials, a final product (product plate) with the chemical composition shown in Table 2 (mass %, the remainder other than indicated is Fe) is manufactured. The resulting steel plate has a width of 1200 mm.

[0188] In Tables 1 and 2, "-" indicates elements for which no conscious content control or manufacturing was carried out, and for which no content determination was performed. Furthermore, "<0.002" and "<0.004" indicate elements for which conscious content control or manufacturing was carried out, and for which content determination was performed, but whose accuracy and reliability were not accurately measured (below the detection limit).

[0189]

[0190]

[0191] Furthermore, details of the steel plate manufacturing process and conditions are shown in Table 3A.

[0192] Specifically, the process involves hot rolling, hot-rolled sheet annealing, and cold rolling. As part of this, the decarburized annealed cold-rolled steel sheet is subjected to nitriding treatment (nitriding annealing) in a mixed atmosphere of hydrogen, nitrogen, and ammonia.

[0193] In addition, a final annealing is performed by applying an annealing separating agent whose main components are magnesium oxide or aluminum oxide, with varying mixing ratios. An insulating coating solution, primarily composed of phosphate and colloidal silica and containing chromium, is applied to the primary coating film formed on the surface of the final annealed steel sheet, and then heat-treated to form an insulating coating film. During this process, the tension and nitrogen content of the steel sheet during decarburizing and nitriding annealing are appropriately varied, further altering the degree of crystal orientation dispersion.

[0194] In this way, a steel sheet was manufactured in which the variation of crystal orientation in the planar portion adjacent to the curved portion was controlled. Details of the manufactured steel sheet are shown in Table 3B.

[0195]

[0196]

[0197] (Iron core)

[0198] Using various steel plates as raw materials, manufacture products with the features shown in Table 4 and... Figure 9 The cores No. a to f are shown in the diagram. Furthermore, L1, parallel to the X-axis, is the distance between the parallel directional electromagnetic steel plates 1 located at the innermost circumference of the wound core in the cross-section including the center CL (distance between inner side planar portions). L2, parallel to the Z-axis, is the distance between the parallel directional electromagnetic steel plates 1 located at the innermost circumference of the wound core in the longitudinal section including the center CL (distance between inner side planar portions). L3, parallel to the X-axis, is the stacking thickness of the wound core in the cross-section including the center CL (thickness in the stacking direction). L4, parallel to the X-axis, is the width of the stacked steel plates of the wound core in the cross-section including the center CL. L5 is the distance between the innermost planar portions of the wound core that are adjacent to each other and simultaneously form right angles (distance between curved portions). In other words, L5 is the length in the length direction of the shortest planar portion 4a among the planar portions 4 and 4a of the innermost circumference directional electromagnetic steel plate 1. r is the radius of curvature (mm) of the curved portion on the inner side of the wound iron core, and Φ is the bending angle (°) of the curved portion on the inner side of the wound iron core. The roughly rectangular iron cores No.a to f are divided at approximately the center of the inner side plane at a distance of L1, forming a structure consisting of two iron cores with a roughly "U-shaped" shape.

[0199] Here, the core of core No. f is a cylindrical core manufactured using the following method. In this method, steel plates that can be used as ordinary wound cores are wound into a cylindrical shape, and then pressed in their original cylindrical laminated form, so that the corners have a constant curvature, forming a roughly rectangular shape. Therefore, the radius of curvature r (mm) of the bend varies considerably depending on the stacking position of the steel plates. In Table 4, the radius of curvature r (mm) of core No. f increases towards the outer periphery, with r = 6 mm at the innermost periphery and r = 60 mm at the outermost periphery (marked with "※" in Table 4).

[0200]

[0201] (Evaluation Method)

[0202] (1) Magnetic properties of directional electromagnetic steel plates

[0203] The magnetic properties of the directional electromagnetic steel sheet were determined based on the Single Sheet Tester (SST) method specified in JIS C 2556:2015.

[0204] As a magnetic property, the magnetic flux density B8(T) in the rolling direction of the steel plate was measured when it was excited at 800 A / m, and the iron loss of the steel plate was measured at an AC frequency of 50 Hz and an excitation magnetic flux density of 1.7 T.

[0205] (2) Core characteristics

[0206] For the steel plates selected from the iron core as described above, Nt / Nx, Nb / Nt, Nb / Na, Nb / Nc, and Φave were calculated. Furthermore, the measurements were performed with Nt reaching 60.

[0207] (3) Efficiency of the iron core

[0208] The iron loss of the iron core was determined for each steel plate used as raw material. The building factor (BF) was then calculated by obtaining the ratio of the magnetic properties of the steel plate (iron core loss / raw material iron loss) to the iron loss of the steel plate obtained according to (1). Here, BF is the value obtained by dividing the iron loss value of the wound iron core by the iron loss value of the raw material of the wound iron core, i.e., the directional electromagnetic steel plate. The smaller the BF, the lower the iron loss of the wound iron core relative to the raw material steel plate. Furthermore, in this embodiment, a BF of 1.08 or less is considered to suppress the deterioration of iron loss efficiency.

[0209] The efficiency of various cores manufactured using steel plates with different crystal orientations in the planar portion adjacent to the bend was evaluated. The results are shown in Tables 5A and 5B. In Tables 5A and 5B, the "-" for Nb / Nc indicates that the value is infinitely large (the value cannot be calculated) because the denominator Nc is zero. For these, it is judged that Nb / Nc is very large and satisfies equation (4). It is found that even when using the same steel grade, the core efficiency can be improved by properly controlling the crystal orientation. Furthermore, the tests No. "1-21" to "1-28" are cores outside the invention range with a large radius of curvature r of the bend, which confirms that the efficiency of Φ 3D Examples of the effects. From these examples, we know that as long as the radius of curvature r of the bend is not designed to be less than a specific value for a specially shaped iron core, even if the Φ near the bend is... 3D Significant changes cannot be expected to produce the characteristic improvement in core efficiency that this invention offers.

[0210]

[0211]

[0212] The results above show that the wound core of the present invention has low iron loss characteristics on the planar portion near at least one bent portion of any directional electromagnetic steel plate being stacked, because it satisfies the above formulas (1) to (5).

[0213] Industrial availability

[0214] According to the present invention, in a wound iron core formed by stacking bent steel plates, the deterioration of iron core efficiency can be effectively suppressed.

[0215] Symbol explanation:

[0216] 1. Directional Electromagnetic Steel Sheet

[0217] 2. Layered structure

[0218] 3. Corner

[0219] 4 (4a, 4b) Planar part

[0220] 5. Bending section

[0221] 6. Joint

[0222] 10. Winded iron core body

Claims

1. A wound iron core, comprising a wound iron core body that is generally polygonal in shape when viewed from the side, characterized in that: The wound core body comprises a portion formed by stacking directional electromagnetic steel plates in the thickness direction, with alternating planar portions and curved portions in the length direction, and has a stacked structure that appears roughly polygonal in side view. The inner side curvature radius r of the curved portion in the side view is more than 1 mm and less than 5 mm; In the directional electromagnetic steel plate, Its chemical composition, expressed as a percentage by mass, contains: Si: 2.0–7.0% The remaining portion includes Fe and impurities. It has a texture oriented towards the Goss orientation; and In one or more of the planar portions adjacent to at least one of the curved portions, the following equations (1) to (4) are satisfied. 0.10≤Nt / Nx≤0.80 (1) 0.37≤Nb / Nt≤0.80 (2) 1.07≤Nb / Na≤4.00 (3), Nb / Nc≥1.10 (4), Here, Nx in the formula (1) is: when multiple measuring points are arranged at 5mm intervals in the region of the planar portion adjacent to the curved portion, in the parallel direction parallel to the boundary of the curved portion and the planar portion, i.e. the boundary of the curved portion, in the parallel direction, the total number of grain boundary determination points that exist in the center of two adjacent measuring points in the parallel direction for determining whether there is a grain boundary between the two measuring points. Furthermore, regarding the crystal orientation observed in the directional electromagnetic steel sheet, The offset angle from the ideal Goss orientation, with the normal direction Z of the rolled surface as the axis of rotation, is defined as α. The offset angle from the ideal Goss orientation, with the rolling right-angle direction C as the rotation axis, is defined as β. The offset angle from the ideal Goss orientation with the rolling direction L as the rotation axis is defined as γ. When the misorientation angles of the crystal orientation measured at the two measurement points are expressed as (α1, β1, γ1) and (α2, β2, γ2), the angle Φ obtained by the following equation (6) 3D When the three-dimensional orientation difference of the misorientation angle α, the misorientation angle β, and the misorientation angle γ is defined, Nt in the formula (1), (2) is: meet Φ 3D the number of grain boundary determination points of ≥1.0°, The Na in the formula (3) is: satisfies Φ 3D The number of the grain boundary determination points of 1.0° or more and less than 2.5°, In equations (2) and (3), Nb is: satisfying Φ 3D The number of grain boundary criteria points with a gradient greater than 2.5° and less than 4.0°. In equation (4), Nc is: Φ 3D The number of grain boundary determination points above 4.0°; F 3D =[(α2-α1) 2 +(β2-β1) 2 +(γ2-γ1) 2 ] 1 / 2 (6).

2. The wound iron core according to claim 1, characterized in that: In the planar portion adjacent to at least one of the curved portions, the following equation (5) is satisfied. F 3D ave:2.0°~4.0° (5), Here, Φ 3D ave satisfies Φ 3D Φ at grain boundary criterion point ≥1.0° 3D The average value.

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