Winding core

Abstract

To provide a winding iron core that is formed by a method of laminating bent steel plates to form a winding iron core, the winding iron core being highly efficient by appropriately arranging flat surface parts.SOLUTION: A winding iron core includes: directional electromagnetic steel plates 1 laminated in a plate thickness direction; and a winding iron core body substantially rectangular in a side view. In the winding iron core body, a flat surface part and a bent surface part alternately continue to each other in a longer direction. Also, an inner surface side curvature radius r in a side surface view of the bent surface part is not larger than 3 mm, and when a region where a bent surface part with 10-80° angles and a flat surface part with a length of 3-8 mm alternately continue to each other in a circumferential direction of the winding iron core in a side view of at least one bent surface part of an arbitrary one of the laminated directional electromagnetic steel plates is a region A, the number of the directional electromagnetic steel plates in which the region A exists is Ma, and a total number of laminated layers is Mtotal, Ma / Mtotal≥0.30(1) is satisfied.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a wound core.

Background Art

[0002] A grain-oriented electrical steel sheet contains 7 mass% or less of Si and has a secondary recrystallized texture in which secondary recrystallized grains are aggregated in the {110}<001> orientation (Goss orientation). The magnetic properties of the grain-oriented electrical steel sheet are greatly affected by the degree of aggregation in the {110}<001> orientation. In recent years, in the grain-oriented electrical steel sheets that are in practical use, the angle between the <001> direction of the crystal and the rolling direction is controlled to be within a range of about 5°, and for example, high magnetic flux density and low iron loss, which are the main magnetic properties, are ensured by sophisticated orientation control techniques such as those disclosed in Patent Documents 1 to 3.

[0003] The grain-oriented electrical steel sheets are laminated and used for cores of transformers, etc. Conventionally, in the manufacture of a wound core, for example, as described in Patent Document 4, after winding a steel sheet into a cylindrical shape, the cylindrical laminate is formed into a rectangle by pressing and annealed to remove strain and maintain the shape. This method is widely known.

[0004] On the other hand, as another manufacturing method of a wound core, a technique as disclosed in Patent Documents 5 to 8 is known, in which a part of the steel sheet that becomes the corner part of the wound core is pre-bent so that a relatively small bending region having a curvature radius of 3 mm or less is formed, and the bent steel sheets are laminated to form a wound core. According to this manufacturing method, a large-scale pressing process as in the conventional method is unnecessary, the steel sheet is precisely bent and the core shape is maintained, and the processing strain also concentrates only on the bent part (corner part), so that the omission of the strain removal by the annealing process is also possible, and the industrial merit is large and the application is progressing.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

[0006] The inventors of the present application have studied further reduction of iron loss in a transformer core manufactured by a method in which a steel plate is pre-bent so that a relatively small bending region having a curvature radius of 3 mm or less is formed, and the bent steel plates are laminated to form a wound core. The core is configured such that the bent portions and the flat portions are alternately arranged, and one of the merits is that good core efficiency can be exhibited without performing stress relief annealing after core formation (after bending) by limiting the deformation region to very narrow bent portions with respect to the entire core. For this reason, many studies have been conducted on the form and structure of the bent portions, but there are few examination cases based on the technical idea of optimizing the arrangement and configuration of the bent portions in relation to the flat portions.

[0007] The inventor has studied the arrangement of the bent portions, specifically, the interval between adjacent bent portions (the length of the flat portion). As a result, it has been found that when the core member is bent and deformed by a specific angle, the core efficiency can be improved by appropriately controlling the length of the flat portion within that region.

[0008] In the conventional core design, for example, when the core has a substantially rectangular shape with four corner portions where the bending angle is 90°, designs such as arranging two 45° bending portions at each corner portion or arranging three 30° bending portions at each corner portion have been carried out. Further, in accordance with the fact that the total outer peripheral extension distance becomes longer toward the outside in the stacking direction of the steel plates, the length of the flat portion arranged at the corner portion is designed to be longer for the outer member. In particular, when the number of stacked steel plates increases and the core stacking thickness becomes thicker, the outer peripheral member has to be long.

[0009] In contrast, the inventors of the present invention studied a design in which the length of the flat portion arranged at the corner portion is limited within a specific range and made substantially constant. As a result, it was confirmed that the core efficiency is improved by adopting a design in which the bending portions within the corner portion are arranged at a relatively short distance. From this perspective, various shapes were studied, and the inventors succeeded in specifying the characteristics of an appropriate flat portion arrangement.

[0010] The present invention has been made in view of the above problems, and provides a wound core manufactured by a method of pre-bending a steel plate so that a relatively small bending region having a curvature radius of 3 mm or less is formed, and stacking the bent steel plates to form a wound core, and improving the core efficiency by appropriately arranging flat portions having appropriate lengths.

Means for Solving the Problems

[0011] In order to achieve the above object, a wound core according to the present invention is a wound core in which directionally electromagnetic steel plates are stacked in the plate thickness direction and are substantially rectangular in side view, in the directionally electromagnetic steel plate, a flat portion and a bending portion are continuously arranged alternately in the longitudinal direction, an inner surface side curvature radius r in side view of the bending portion is 3 mm or less, the directionally electromagnetic steel plate by mass%, contains 2.0 to 7.0% of Si, and the balance is composed of Fe and impurities, has an aggregate structure oriented in the Goss orientation, and in side view of the stacked directionally electromagnetic steel plates, In the circumferential direction of the wound core, a region where bent portions having an angle of 10° or more and 80° or less and flat portions having a length of 3 to 8 mm are alternately continuous is defined as region A. When the number of oriented electromagnetic steel sheets in which region A exists is Ma and the total number of laminated sheets is Mtotal, Ma / Mtotal≧0.30 ·····(1) It is characterized by satisfying the above.

Effect of the Invention

[0012] According to the present invention, in a wound core manufactured by a method in which a steel sheet is pre-bent so that a relatively small bent region having an inner surface side curvature radius of 3 mm or less is formed, and the bent steel sheets are laminated to form a wound core, good core efficiency can be obtained.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7A

Figure 7B

Figure 7C

Figure 7D

Figure 8

Embodiments for Carrying Out the Invention

[0014] Hereinafter, the wound iron core according to the present invention will be described in detail in order. However, the present invention is not limited only to the configuration disclosed in this embodiment, and various modifications can be made without departing from the spirit of the present invention. In addition, the lower limit value and the upper limit value are included in the numerical limitation range described below. A numerical value indicated as "more than" or "less than" is not included in the numerical range. Further, "%" regarding the chemical composition means "mass%" unless otherwise specified. In addition, terms used in this specification for specifying shapes, geometric conditions, and their degrees, such as terms like "parallel", "perpendicular", "identical", "right angle", and values of lengths and angles, etc., shall not be bound by a strict meaning, and shall be interpreted to include a range to the extent that a similar function can be expected. In addition, in this specification, the "directional electromagnetic steel sheet" may sometimes be simply described as "steel sheet" or "electromagnetic steel sheet", and the "wound iron core" may sometimes be simply described as "iron core".

[0015] The wound iron core according to an embodiment of the present invention is a wound iron core in which directional electromagnetic steel sheets are laminated in the plate thickness direction and are substantially rectangular in side view, In the directional electromagnetic steel sheet, a flat portion and a bent portion are alternately continuous in the longitudinal direction, The inner surface side curvature radius r in side view of the bent portion is 3 mm or less, The directional electromagnetic steel sheet by mass, contains 2.0 to 7.0% of Si, and has a chemical composition consisting of the balance of Fe and impurities, has an aggregate structure oriented in the Goss orientation, and in side view of any of the laminated directional electromagnetic steel sheets, In the circumferential direction of the wound core, a region where bent portions having an angle of 5° or more and 80° or less and flat portions having a length of 3 to 8 mm are alternately continuous is defined as region A. When the number of oriented electromagnetic steel sheets in which region A exists is Ma and the total number of stacked sheets is Mtotal, Ma / Mtotal ≧ 0.30 ·····(1) It is characterized by satisfying the above.

[0016] 1. Shape of the wound core and the oriented electromagnetic steel sheet First, the shape of the wound core of the present invention will be described. The shapes of the wound core and the oriented electromagnetic steel sheet described here are not particularly novel. For example, they conform to the shapes of known wound cores and oriented electromagnetic steel sheets introduced as Patent Documents 5 to 8 in the background art. FIG. 1 is a perspective view schematically showing an embodiment of the wound core. FIG. 2 is a side view of the wound core shown in the embodiment of FIG. 1. FIG. 3 is a side view schematically showing another embodiment of the wound core. In the present invention, the side view means viewing in the width direction of the long-sized oriented electromagnetic steel sheet constituting the wound core (the Y-axis direction in FIG. 1), and the side view is a view showing the shape visually recognized by the side view (the view in the Y-axis direction of FIG. 1).

[0017] The wound core of the present invention includes a wound core body having a substantially rectangular shape in side view. The wound core body has a laminated structure in which oriented electromagnetic steel sheets are stacked in the plate thickness direction and have a substantially rectangular shape in side view. The wound core body may be used as the wound core as it is, or may be provided with known fasteners such as binding bands as necessary to fix the wound core.

[0018] In the present invention, there is no particular limitation on the core length of the wound core body. However, even if the core length changes in the core, since the volume of the bent portion is constant, the iron loss generated in the bent portion is constant. Since the volume ratio of the bent portion becomes smaller when the core length is longer, the influence on the deterioration of iron loss is also small, so it is preferably 1.5 m or more, and more preferably 1.7 m or more. In the present invention, the core length of the wound core body refers to the peripheral length at the center point in the stacking direction of the wound core body in side view.

[0019] The wound core of the present invention can be suitably used for any conventionally known applications.

[0020] As shown in FIGS. 1 and 2, the wound core body 10 includes a portion where the directional electromagnetic steel sheets 1 in which the flat portions 4 and the corner portions 3 are alternately continuous in the longitudinal direction and the angle formed by two adjacent flat portions 4 at each corner portion 3 is 90° are stacked in the plate thickness direction, and has a substantially rectangular laminated structure 2 in a side view. Viewed in another way, the wound core body 10 has an octagonal laminated structure 2. In the present embodiment, the wound core body 10 has an octagonal laminated structure, but the present invention is not limited thereto. The wound core body may be such that a plurality of polygonal annular directional electromagnetic steel sheets are laminated in the plate thickness direction in a side view, and it is sufficient that the flat portions and the bent portions of the directional electromagnetic steel sheets are alternately continuous in the longitudinal direction (circumferential direction).

[0021] Hereinafter, the wound core body 10 will be described as having a substantially rectangular shape with four corner portions 3. Each corner portion 3 has two bent portions 5 having a curved shape in a side view of the directional electromagnetic steel sheet 1, has a second flat portion 4a between the adjacent bent portions 5, 5, and the sum of the bending angles of the two bent portions 5, 5 existing in one corner portion 3 is 90°. Also, as shown in FIG. 3, each corner portion 3 has three bent portions 5 having a curved shape in a side view of the directional electromagnetic steel sheet 1, has a second flat portion 4a between the adjacent bent portions 5, 5, and the sum of the bending angles of the three bent portions 5, 5, 5 existing in one corner portion 3 is 90°.

[0022] Also, each corner portion 3 may have four or more bent portions. In this case as well, there is a second flat portion 4a between the adjacent bent portions 5, 5, and the sum of the bending angles of the four or more bent portions 5 existing in one corner portion 3 is 90°. That is, each corner portion 3 is disposed between two adjacent first flat portions 4, 4 arranged at right angles, and has two or more bent portions 5 and one or more second flat portions 4a. In addition, in the wound core body 10 shown in FIG. 2, a bent portion 5 is disposed between the first flat portion 4 and the second flat portion 4a, while in the wound core body 10 shown in FIG. 3, bent portions 5 are respectively disposed between the first flat portion 4 and the second flat portion 4a and between the two second flat portions 4a, 4a. That is, the second flat portion 4a may be disposed between two adjacent second flat portions 4a, 4a.

[0023] Furthermore, in the wound core body 10 shown in FIGS. 2 and 3, the first flat portion 4 is longer in the longitudinal direction (circumferential direction of the wound core body 10) than the second flat portion 4a, but the lengths of the first flat portion 4 and the second flat portion 4a may be equal. In this specification, the "first flat portion" and the "second flat portion" may sometimes be simply described as "flat portions" respectively. Each corner portion 3 of the directional electromagnetic steel sheet 1 has two or more bent portions 5 having a curved shape in side view, and the sum of the bending angles of the bent portions existing in one corner portion is 90°. The corner portion 3 has a second flat portion 4a between adjacent bent portions 5, 5. Therefore, the corner portion 3 has a configuration including two or more bent portions 5 and one or more second flat portions 4a. The embodiment of FIG. 2 is a case where two bent portions 5 are provided in one corner portion 3. The embodiment of FIG. 3 is a case where three bent portions 5 are provided in one corner portion 3.

[0024] As shown in these examples, in the present invention, one corner portion can be constituted by two or more bent portions. However, from the viewpoint of suppressing the occurrence of strain due to deformation during processing and suppressing iron loss, the bending angle φ (φ1, φ2, φ3) of the bent portion 5 is preferably 60° or less, and more preferably 45° or less. In the embodiment of FIG. 2 having two bent portions at one corner portion, from the viewpoint of reducing iron loss, for example, φ1 = 60° and φ2 = 30°, or φ1 = 45° and φ2 = 45°, etc. can be set. Further, in the embodiment of FIG. 3 having three bent portions at one corner portion, from the viewpoint of reducing iron loss, for example, φ1 = 30°, φ2 = 30° and φ3 = 30°, etc. can be set. Furthermore, from the viewpoint of production efficiency, since it is preferable that the bending angles are equal, when there are two bent portions at one corner portion, it is preferable to set φ1 = 45° and φ2 = 45°. Also, in the embodiment of FIG. 3 having three bent portions at one corner portion, from the viewpoint of reducing iron loss, for example, it is preferable to set φ1 = 30°, φ2 = 30° and φ3 = 30°.

[0025] Referring to FIG. 6, the bent portion 5 will be described in more detail. FIG. 6 is a diagram schematically showing an example of the bent portion (curved portion) of the grain-oriented electrical steel sheet. The bending angle of the bent portion means the angle difference generated between the straight portion on the rear side in the bending direction and the straight portion on the front side in the bent portion of the grain-oriented electrical steel sheet, and on the outer surface of the grain-oriented electrical steel sheet, it is represented as the angle φ which is the supplementary angle of the angle formed by two virtual lines Lb-elongation1 and Lb-elongation2 obtained by extending the straight line portions which are the surfaces of the flat portions on both sides sandwiching the bent portion. At this time, the point where the extended straight line detaches from the steel sheet surface is the boundary between the flat portion and the bent portion on the surface on the outer side of the steel sheet, and in FIG. 6, they are point F and point G.

[0026] Furthermore, straight lines perpendicular to the outer surface of the steel sheet are extended from each of point F and point G, and the intersection points with the surface on the inner side of the steel sheet are set as point E and point D respectively. These point E and point D are the boundaries between the flat portion and the bent portion on the surface on the inner side of the steel sheet. And in the present invention, the bent portion is the portion of the grain-oriented electrical steel sheet surrounded by the above-mentioned point D, point E, point F, and point G in the side view of the grain-oriented electrical steel sheet. In FIG. 6, the steel sheet surface between point D and point E, that is, the inner surface of the bent portion is shown as La, and the steel sheet surface between point F and point G, that is, the outer surface of the bent portion is shown as Lb.

[0027] In the present invention, the inner surface side radius of curvature of the bent portion is defined in a side view of the bent portion. Taking FIG. 6 as an example, a method for determining the inner surface side radius of curvature of the bent portion will be specifically described. First, on each of the flat portions on both sides sandwiching the bent portion, a straight line that contacts at least 1 mm or more with the straight line portion that is the surface of the flat portion is determined. These are respectively defined as virtual lines Lb-elongation1 and Lb-elongation2, and the intersection point is defined as point B. Ideally, the lengths of line segment BF and line segment BG are the same, but in reality, due to variations in processing conditions and inevitable fluctuations, etc., some differences may occur. Even in such a case, points F' and G' are determined from point B, point F, and point G so that a proper evaluation of the effects of the present invention is possible. That is, the longer distance among line segment BF and line segment BG is defined as LL (for example, assuming that line segment BG is longer than line segment BF). A point that is at a distance LL from point B toward point F on virtual line Lb-elongation1 is defined as point F', and a point that is at a distance LL from point B toward point G on virtual line Lb-elongation2 is defined as point G'. At this time, either point F' or point G' will coincide with the original point F or point G respectively (for example, when line segment BG is longer than line segment BF, point G´ coincides with the original point G). In addition, when the lengths of line segment BF and line segment BG are equal, in FIG. 6, point F´ coincides with the original point F, and accordingly, point E´ described below will coincide with the original point E. Then, a straight line perpendicular to the outer surface of the steel plate is extended from each of point F' and point G', and the intersection point is defined as the center of curvature A. The intersection points of line segments AF' and AG' with the surface La on the inner surface side of the steel plate are defined as point E' and point D' respectively. At this time, the circle passing through point E' and point D' with point A as the center is the surface approximating the bent portion in the present invention, and the length of line segment AE' (which is the same as the length of line segment AD') is the inner surface side radius of curvature in the present invention. In the wound core of the present invention, the inner surface side curvature radius at each bent portion of each grain-oriented electrical steel sheet laminated in the plate thickness direction may have a certain degree of variation. This variation may be due to variations in forming accuracy, or it is also conceivable that unintentional variations occur during handling during lamination. Such unintentional errors can be suppressed to about 0.3 mm or less in current normal industrial manufacturing. When such variations are large, the inner surface side curvature radius can be measured for a sufficiently large number of steel sheets and averaged to obtain a representative value. Also, although it is conceivable to intentionally change it for some reason, the present invention does not exclude such a form. In the present invention, it is assumed that the inner surface side curvature radius r is 3 mm or less. As will be described later, considering that the main action of the present invention is brought about by the magnetic domain control effect in the flat portion having a length of 3 to 8 mm, simply, the size of the bent portion that divides the flat portion should not occupy a large area within the corner portion. Generally, in a wound core formed by laminating electrical steel sheets having bent portions with a relatively small inner surface side curvature radius targeted by the present invention, it is a well-known technique that it is preferable to reduce the inner surface side curvature radius of the bent portion from the viewpoint of magnetic properties, and technological development has been made in that direction for such cores. The present invention also takes this into account and sets the inner surface side curvature radius of the bent portion to 3 mm or less. From the above two viewpoints, it is clear that it is preferable for the inner surface side curvature radius to be small, preferably 2 mm or less, and more preferably 1 mm or less.

[0028] In the wound core of the present invention, the inner surface side curvature radius at each bent portion of each grain-oriented electrical steel sheet laminated in the plate thickness direction may have a certain degree of variation. This variation may be due to the forming accuracy, or it is also conceivable that unintentional variations occur during handling during lamination. Such unintentional errors can be suppressed to about 0.3 mm or less in current normal industrial manufacturing. When such variations are large, a representative value can be obtained by measuring and averaging the inner surface side curvature radii of a sufficiently large number of steel sheets. Also, for some reason, it is conceivable to intentionally change the inner surface side curvature radius of the bent portion at a specific part in the core, but the present invention does not exclude such a form.

[0029] Note that there is no particular limitation on the method for measuring the form of the bent portion. For example, it can be measured by observing with a commercially available microscope (Nikon ECLIPSE LV150) at a magnification as required. In the present invention, by setting the inner surface side curvature radius r of the bent portion in the range of 3 mm or less and controlling the form of the bent portion described below within a specific range, it has become possible to improve the efficiency of the wound core.

[0030] Figures 4 and 5 are diagrams schematically showing an example of a single layer of grain-oriented electrical steel sheet in the wound core body. As shown in the examples of Figures 4 and 5, the grain-oriented electrical steel sheet used in the present invention is bent, has a corner portion 3 composed of two or more bent portions 5 and a flat portion 4, and forms a substantially rectangular ring in side view through a joint portion 6 at the width direction end face of one or more grain-oriented electrical steel sheets. In the present invention, it is only necessary for the wound core body to have a laminated structure that is substantially rectangular in side view as a whole. As shown in the example of Figure 4, one grain-oriented electrical steel sheet may constitute one layer of the wound core body through one joint portion 6, or as shown in the example of Figure 5, one grain-oriented electrical steel sheet may constitute about half a circumference of the wound core, and two grain-oriented electrical steel sheets may constitute one layer of the wound core body through two joint portions 6.

[0031] The thickness of the grain-oriented electrical steel sheet used in the present invention is not particularly limited and may be appropriately selected according to the application and the like. Usually, it is in the range of 0.10 mm to 0.35 mm, preferably in the range of 0.15 mm to 0.23 mm.

[0032] 2. Forms of the bent portion and the flat portion Here, the characteristics of the forms of the bent portion and the flat portion of the grain-oriented electrical steel sheet constituting the wound core body, which is one of the embodiments of the present invention, will be described with reference to FIGS. 7A to 7D.

[0033] In the present embodiment, the invention is defined by the form of the grain-oriented electrical steel sheet in a side view of the grain-oriented electrical steel sheets laminated as a wound core. In this side view, a bent portion (hereinafter, may also be referred to as a "target bent portion") having a bending angle of 5° or more and 80° or less, and a flat portion (hereinafter, may also be referred to as a "target flat portion") having a length of 3 to 8 mm are defined as targets. And in at least a part of the laminated grain-oriented electrical steel sheets, there exists a region (hereinafter, referred to as "region A") in which the above-mentioned target bent portion and the above-mentioned target flat portion are continuously alternated in the circumferential direction of the wound core. And when the total number of laminated sheets is Mtotal and the number of grain-oriented electrical steel sheets in which region A exists among all the laminated electrical steel sheets is Ma, Ma / Mtotal≧0.30 ·····(1) is satisfied.

[0034] The number of corner portions of the wound core assumed in the present invention is not limited, but generally, it is substantially rectangular in a side view. That is, there are four corner portions bent at 90°, and the flat portions between the corner portions are relatively long compared to the size of the corner portions. Taking this shape as a representative example, the above characteristics of the present invention will be described in more detail.

[0035] The bending angle of the target bending part in the present invention is set to 80° or less. As described above, the core itself targeted by the present invention is characterized by preferably controlling the core characteristics by dispersing the bending parts, and it is premised that the angle of one bending process is basically small. However, in the present invention, in relation to the mechanism of manifestation of the effects of the present invention described later, the angle of one bending process defined by the invention needs to be small. Although details will be described later, the effect of the present invention is based on the basic mechanism of magnetic domain subdivision by the bending part. If the bending angle becomes large and excessive strain is generated at the bending part, the magnetic domain structure will not be preferable and the effect of the invention cannot be obtained. Preferably it is 60° or less, more preferably 45° or less, and even more preferably 30° or less. On the other hand, since magnetic domain subdivision is brought about by the strain introduced into the steel sheet, if the bending angle is too small, the cost may increase due to an increase in the number of bending locations, or the magnetic domain control effect itself may weaken. Therefore, the bending angle of the target bending part is set to 5° or more. Preferably it is 10° or more, and more preferably 15° or more.

[0036] The circumferential length of the target flat part of the wound core in the present invention is set to 3 to 8 mm. As described above, this is related to the optimal magnetic domain size in the flat part when the magnetic domain is subdivided by the bending part. Generally, the crystal grain size of the grain-oriented electrical steel sheet is about 50 mm, and the magnetic domains also exist in a size of this order. The technology for subdividing this to improve the magnetic properties is so-called "magnetic domain control", and the magnetic domains are subdivided by mechanical processing, etching, high-energy ray irradiation, etc. in a local area on the steel sheet surface. And it is said that the appropriate magnetic domain size at that time is around 5 mm. The present invention applies the magnetic domain control technology utilized in a flat grain-oriented electrical steel sheet to a wound core manufactured by bending. Therefore, it is considered that the size of the target flat part defined by the present invention is close to about 5 mm, which is the optimal magnetic domain size in the grain-oriented electrical steel sheet with a flat shape. Preferably it is 4 to 7 mm.

[0037] In this embodiment, the target bent portion and the target flat portion are alternately and continuously formed to ensure a large bending angle of the entire steel plate in a relatively narrow area. That is, a portion corresponding to the corner portion of the rectangular core is formed. For example, in the case of a 90° corner portion, two 45° bent portions are arranged, and the length of the flat portion between the bent portions is designed to be 3 to 8 mm (see, for example, FIG. 7A). Or three 30° bent portions are arranged, and the length of each of the two flat portions between the bent portions is designed to be 3 to 8 mm (see, for example, FIG. 7D). In the following, for easy understanding, the length of the flat portion will be described as 5 mm.

[0038] As described above, when one steel plate constituting the core (for example, the nth steel plate laminated from the innermost peripheral steel plate toward the outer periphery) is provided with, for example, two 45° bent portions and the length of the flat portion between the bent portions is designed to be 5 mm, the extension distance along the circumferential direction of the core at the corner portion is about 5 mm. Also, when three 30° bent portions are provided and the lengths of the two flat portions between the bent portions are each designed to be 5 mm, the extension distance at the corner portion is about 10 mm. This is the shape of one steel plate. If the above extension distance at the corner portion is constant in all the laminated grain-oriented electrical steel sheets, it is only necessary to laminate the steel plates bent in that design. However, the circumferential length of the core becomes longer toward the outer peripheral portion of the lamination. Further, in order to prevent a gap from occurring in the steel plates laminated at the corner portion, generally, the above extension distance at the corner portion is also designed to be longer. Specifically, when the (n + 1)th steel plate outside the nth steel plate is laminated so that the flat portions contact as much as possible, since the steel plate bends at a position of 22.5° where the 45° bent portions have an equal angle, the length of the flat portion becomes longer than 5 mm. For example, when the length between the bent portions of the flat portion of the innermost n = 1st steel plate is L0, the stacked thickness T is n × t / vf, where t is the plate thickness, n is the number of stacked sheets, and vf is the occupation ratio at the time of stacking. The length of the nth flat portion becomes longer, such as L0 + 2T·tan22.5°C (Fig. 7A). That is, if the steel plate laminated on the innermost periphery is bent with the above design (the length of the flat portion is 5 mm), it is necessary to lengthen the flat portion toward the outer peripheral side in the steel plate laminated on the outer periphery. Then, at a certain stacked thickness or more, it becomes impossible to maintain the length of the flat portion within the corner portion to 8 mm or less. When the length of the flat portion becomes longer in this way, it causes deterioration of characteristics from the viewpoint of the magnetic domain control described above. To avoid this deterioration, in the present embodiment, a design is made to avoid an increase in the length of the flat portion at the outer peripheral portion.

[0039] One is, for example, a form in which laminations are made while keeping the length of the flat portion constant as shown in FIG. 7B. Alternatively, as shown in FIG. 7C, although the length of the flat portion increases toward the outer periphery, when it becomes excessively long, a steel plate with a shorter flat portion length than that is laminated on the outer peripheral side thereof. By doing so, even when the extension distance of one corner portion becomes long, it becomes possible to enjoy a good magnetic domain subdivision effect at the corner portion.

[0040] Here, referring again to the differences among FIGS. 7A, 7B, and 7C, the steel plate lamination method of FIG. 7A is a normal lamination method for a uncore, and it is a lamination method in which the steel plates are brought into contact with each other as much as possible including the flat portions of the steel plates at the corner portions, whereas in FIG. 7B, in order to make the length L of the flat portion of the steel plate at the corner portion fall within the range of 3 mm to 8 mm, the voids (the white portions between the steel plates (black portions) in FIG. 7B) generated between the steel plates of the flat portion at the corner portion are uniformly scattered in the stacking direction. Further, in FIG. 7C, the steel plates are brought into contact with each other as much as possible including the flat portions of the steel plates at the corner portion, and when the length L of the flat portion of the steel plate at the corner portion becomes long along with the number of stacked sheets, L is shortened again to fall within the range of 3 mm to 8 mm, and the voids generated between the steel plates of the flat portion at the corner portion are accumulated between the lamination of the steel plate with a long L and the steel plate with a short L.

[0041] Also, of course, an intermediate lamination method between FIGS. 7A and 7B is possible, and a combination of FIGS. 7B and 7C is also possible, and as long as the requirements of the present invention are satisfied, the effect of magnetic domain subdivision can be enjoyed. Furthermore, as shown in FIG. 7D, it is also possible to maintain the length of the flat portion at 8 mm or less by increasing the number of bent portions at a specific point toward the outer periphery. For example, when a design is made in which two 45° bent portions are arranged at the innermost periphery and the length of the flat portion between the bent portions is 3 mm, three 30° bent portions are arranged at the outer peripheral portion than a certain position, and the lengths of the two flat portions between the bent portions can be maintained at about 5 mm each. Further, if the length of the flat portion excessively increases at the outer peripheral portion, four 22.5° bent portions are arranged at the outer peripheral portion than that, and the lengths of the three flat portions between the bent portions can be maintained at about 5 mm each.

[0042] In FIGS. 7B, 7C, and 7D, the lengths of all the flat portions within the corner portion satisfy 3 to 8 mm. However, if some of the flat portions within the corner portion satisfy the length of 3 to 8 mm, the invention effect can be obtained. There may be flat portions having lengths outside the specified range in the stacking direction. Also, there may be flat portions having lengths outside the specified range in the circumferential direction of the iron core. Thus, when some of the flat portions within the corner portion do not satisfy the invention requirements, if the ratio of the flat portions satisfying the invention requirements is the same, the flat portions satisfying the invention requirements are preferably arranged on the inner peripheral side. This is because when the iron core is excited, the magnetic flux concentrates on the inner peripheral side, and it is advantageous to enjoy the magnetic domain control effect in this region.

[0043] In the embodiment of the present invention, the above configuration is defined as follows. That is, in a side view of the laminated grain-oriented electrical steel sheets, in the circumferential direction of the wound iron core, a region where a bent portion having an angle of 5° or more and 80° or less and a flat portion having a length of 3 to 8 mm are alternately continuous is defined as region A. When the number of grain-oriented electrical steel sheets in which region A exists is Ma and the total number of stacked sheets is Mtotal, Ma / Mtotal>0.30 ·····(1) is satisfied. Ma / Mtotal is preferably 0.50 or more, and more preferably 0.8 or more. Basically, it is preferable that all the laminated steel sheets of the iron core, that is, from the innermost peripheral steel sheet to the outermost peripheral steel sheet, conform to the requirements of the present invention, that is, Ma / Mtotal = 1.00. Also, although the invention effect can be obtained if formula (1) is satisfied for the entire iron core, it is preferable that formula (1) is satisfied even when limited to one corner portion, and further that formula (1) is satisfied for all corner portions.

[0044] In a normal single-core, although it depends on the design, the number of laminated steel plates is often 100 or more, and the laminated thickness is often 40 mm or more. In the normal lamination method as shown in Fig. 7A, Ma / Mtotal cannot be set to 1.00. As described above, when the number of laminated steel plates increases and the laminated thickness of the core becomes thicker, the members on the outer periphery have to be lengthened. In the normal lamination method as shown in Fig. 7A, when the laminated thickness of the core becomes 16 mm or more, the formula (1) cannot be satisfied, and good core characteristics cannot be obtained. As a specific method for ensuring that the length of the flat portion between the bent portions falls within the range of 3 mm to 8 mm in all the laminated steel plates, as described above, as shown in Fig. 7B, the lamination method of the corner portion is made different from the normal one, or as shown in Fig. 7C, while keeping the number of bent portions at the corner portion unchanged, a method of providing a gap at the corner portion in the lamination of the n-th and the next (n + 1)-th steel plates within the range where the outer periphery does not exceed 8 mm, or as shown in Fig. 7D, a method of providing a gap at the corner portion and further increasing the number of bent portions in the lamination of the n-th and the next (n + 1)-th steel plates within the range where the outer periphery does not exceed 8 mm, or a combined method thereof, etc. are available. Also, if the angle of the bent portion and the length of the flat portion can be maintained within an appropriate range, when increasing the number of bent portions by adopting the method shown in Fig. 7D, they may be increased by two or more at a time. Here, although the length of the flat portion between the bent portions has been described as falling within the range of 3 mm to 8 mm, within the range that satisfies the formula (1), it is also possible that the length of the flat portion of a part of the laminated steel plates is less than 3 mm or more than 8 mm.

[0045] In the present invention, the features of FIGS. 7B, 7C, and 7D described above are defined as follows. First, the feature of Fig. 7B is defined as preferable. In this definition, a region A where the length of the target flat portion in the circumferential direction of the core is the same, the target flat portions are laminated in parallel and continuously, when the bending angle of the target bent portion in the region A is Φ, the thickness in the direction perpendicular to the target flat portion of the region where the target flat portions are laminated in parallel and continuously is H, and the laminated thickness of the steel plates laminated in the region is Lx, Lx / H / cosΦ: 0.97 to 1.03 ·····(2) is satisfied. Here, the value on the left side of equation (2) is preferably 1.00. However, in reality, since there are some gaps and variations in shape in the stacking of steel plates, a variation of about 3% is allowed. Equation (2) means that the value of Lx / H / cosΦ on the left side is 0.97 to 1.03. In other words, it means 0.97 ≦ Lx / H / cosΦ ≦ 1.03. In the wound core shown in Fig. 7B, the shapes of the side views of the corner portions of all the steel plates are the same, and a gap is formed between the target plane portions that form the corner portions in the steel plates adjacent in the stacking direction. The shapes of the side views of each gap are the same. Here, the stacking thickness Lx is different from the stacking thickness L3 in that it is limited to the region where the target plane portions are stacked in parallel and continuously (hereinafter, also referred to as the target region). When the target plane portions are stacked in parallel and continuously over the entire stacking direction, Lx = L3. However, when the target plane portions are stacked in parallel and continuously only in a part of the stacking direction, Lx < L3. The stacking thickness Lx can be, for example, the stacking thickness of the steel plate in the first plane portion adjacent to the corner portion including the target region.

[0046] The second is to define the features of Fig. 7C as preferable. In this definition, at least two regions A are arranged with the target plane portions of each region A stacked in parallel, let the bending angle of the target bending portion constituting the region A be Φ, let the length in the circumferential direction of the iron core of the target plane portion arranged on the inner surface side of the iron core be Ln, let the length in the circumferential direction of the iron core of the target plane portion arranged on the outer surface side of the iron core be Lm, and when the distance between the above two target plane portions is further defined as Lh, Lm < Ln ·····(3) Lh / {(Ln - Lm) / 2} / tanΦ > 0.98 ·····(4) is satisfied. Here, the value on the left side of equation (4) is preferably greater than 1.00. However, in reality, since there are some gaps and shape variations in the stacking of steel plates, a variation of about 2% is allowed. In the case of the wound core shown in FIG. 7C, four stacked bodies of steel plates are provided (note that the number of stacked bodies is not limited to four, but the wound core shown in FIG. 7C is of a multi-block type having a plurality of stacked bodies (blocks)). In each stacked body, at the corner portion of the steel plate, although the number of bent portions is the same, the circumferential length of the flat portion becomes longer as the steel plate is located more on the outer side in the radial direction. Also, at the corner portions of different stacked bodies, the number of bent portions is the same. Although the four stacked bodies are stacked in the stacking direction of the steel plates, a gap is provided between the corner portions of each other. The circumferential length of the target flat portion arranged on the inner core surface side across the gap is Ln, the circumferential length of the target flat portion arranged on the outer core surface side across the gap is Lm, and the interval in the stacking direction of the target flat portions having Ln and Lm is Lh. Note that Ln and Lm in FIG. 7C are described on the assumption that the lengths of all the flat portions forming the corner portions are within the range of 3 mm to 8 mm (all are in region A). However, the present embodiment is not limited to this, and within the range that satisfies the formula (1), it is possible that the length of a part of the flat portion forming the corner portion is less than 3 mm or more than 8 mm.

[0047] Thirdly, the features of FIG. 7D are defined as preferable. In this definition, at least two regions A are stacked and arranged such that at least one of the target flat portions of each region A is non-parallel, Regarding the region A arranged on the inner core surface side among the two regions A, let the bending angle of the target bent portion be Φn, the number of the target bent portions be Rn, and the average circumferential length of the target flat portion in the core circumferential direction be Ln, Regarding the region A arranged on the outer core surface side among the two regions A, when the bending angle of the target bent portion is Φm, the number of the target bent portions is Rm, and the average circumferential length of the target flat portion in the core circumferential direction is Lm, Φm < Φn ·····(5) Rm > Rn ·····(6) Lm < Ln ·····(7) satisfies the following. In the case of the toroidal core shown in Fig. 7D, three laminates of steel plates are provided (note that the number of laminates is not limited to three, but the toroidal core shown in Fig. 7D is a multi-block type having a plurality of laminates (blocks)). In each laminate, at the corner portion of the steel plate, although the number of bent portions is the same, the circumferential length of the flat portion is longer for the steel plate located on the outer side in the radial direction. At the corner portions of different laminates, the number of bent portions is different. The number of bent portions gradually increases (one by one in the illustrated example) for the laminate located on the outer side in the radial direction. Although the four laminates are laminated in the stacking direction of the steel plates, a gap is provided between the corner portions of each other. The bending angle of the target bent portion disposed on the inner core surface side across the gap is Φn, the number of target bent portions is Rn, and the average length in the circumferential direction of the core of the target flat portion is Ln. The bending angle of the target bent portion disposed on the outer core surface side across the gap is Φm, the number of target bent portions is Rm, and the average length in the circumferential direction of the core of the target flat portion is Lm. Note that the descriptions of Φn, Ln, Φm, and Lm in Fig. 7D refer to the values of Φn, Ln, Φm, and Lm when attention is paid to the relationship between the laminate located on the outermost side in the radial direction and the laminate located in the middle in the radial direction among the three laminates, where the length of the flat portion forming the corner portion is all within the range of 3 mm to 8 mm (all in region A). However, the present embodiment is not limited to this, and within the range satisfying the formula (1), it is possible to make the length of a part of the flat portion forming the corner portion less than 3 mm or more than 8 mm.

[0048] 3. Grain-oriented electrical steel sheet As described above, in the grain-oriented electrical steel sheet used in the present invention, the mother steel sheet is a steel sheet in which the orientation of crystal grains in the mother steel sheet is highly concentrated in the {110}<001> orientation and has excellent magnetic properties in the rolling direction. In the present invention, a known grain-oriented electrical steel sheet can be used as the mother steel sheet. Hereinafter, an example of a preferable mother steel sheet will be described.

[0049] The chemical composition of the mother steel plate contains Si: 2.0% to 7.0% by mass, and the balance is composed of Fe. This chemical composition is to control the crystal orientation to a Goss texture in which the {110}<001> orientation is aggregated to ensure good magnetic properties. Regarding other elements, there is no particular limitation, and it is allowed to contain known elements within a known range in place of Fe. The typical content ranges of typical elements are as follows. C: 0 to 0.0050%, Mn: 0 to 1.0%, S: 0 to 0.0150%, Se: 0 to 0.0150%, Al: 0 to 0.0650%, N: 0 to 0.0050%, Cu: 0 to 0.40%, Bi: 0 to 0.010%, B: 0 to 0.080%, P: 0 to 0.50%, Ti: 0 to 0.0150%, Sn: 0 to 0.10%, Sb: 0 to 0.10%, Cr: 0 to 0.30%, Ni: 0 to 1.0%, Nb: 0 to 0.030%, V: 0 to 0.030%, Mo: 0 to 0.030%, Ta: 0 to 0.030%, W: 0 to 0.030%, These selected elements may be contained according to their purposes, so there is no need to limit the lower limit value, and they may not be substantially contained. Also, even if these selected elements are contained as impurities, the effects of the present invention are not impaired. Note that impurities refer to elements contained unintentionally, and when the mother steel plate is industrially manufactured, they mean elements mixed in from ores, scraps, or manufacturing environments as raw materials.

[0050] The chemical composition of the mother steel plate may be measured by a general analysis method for steel. For example, the chemical composition of the mother steel plate may be measured using ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectrometry). Specifically, for example, a test piece with a size of 35 mm square is obtained from the central position of the mother steel plate after film removal, and it can be specified by measuring under conditions based on a calibration curve prepared in advance using an ICPS-8100 or the like (measurement device) manufactured by Shimadzu Corporation. Note that C and S may be measured using the combustion-infrared absorption method, and N may be measured using the inert gas fusion-thermal conductivity method.

[0051] Note that the above chemical composition is that of a grain-oriented electrical steel sheet. When the grain-oriented electrical steel sheet serving as a measurement sample has a primary film (glass film, intermediate layer), an insulating film, etc. composed of oxides or the like on its surface, these are removed before measuring the chemical composition.

[0052] 4. Manufacturing method of grain-oriented electrical steel sheet The manufacturing method of the mother steel plate is not particularly limited, and a conventionally known manufacturing method of a grain-oriented electrical steel sheet can be appropriately selected. Preferred specific examples of the manufacturing method include, for example, heating a slab having C of 0.04 to 0.1% by mass and the other chemical composition of the above mother steel plate to 1000°C or higher and performing hot rolling, then performing hot-rolled sheet annealing as necessary, and then making it into a cold-rolled steel sheet by cold rolling one or two or more times with an intermediate annealing in between. The cold-rolled steel sheet is heated to 700 to 900°C in a wet hydrogen-inert gas atmosphere for decarburization annealing, and further nitriding annealing is performed as necessary. After applying an annealing separator, finish annealing is performed at about 1000°C, and an insulating film is formed at about 900°C. Further, painting or the like for adjusting the friction coefficient may be performed thereafter. Also, the effects of the present invention can be enjoyed even with a steel sheet obtained by performing a process generally called "magnetic domain control" in a known method in the manufacturing process of the steel sheet.

[0053] 5. Manufacturing method of wound core The basic manufacturing method of the wound core according to the present invention is not particularly limited as long as the wound core according to the present invention can be manufactured. For example, a method according to a known wound core introduced as Patent Documents 5 to 8 in the background art may be applied. In particular, the method of using the manufacturing apparatus of UNICORE (https: / / www.aemcores.com.au / technology / unicore / ) of AEM UNICORE can be said to be optimal.

[0054] Also, the obtained wound core body may be used as a wound core as it is, or may be fixed using known fasteners such as binding bands as needed to form a wound core.

[0055] The present invention is not limited to the above embodiments. The above embodiments are examples, and any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and exhibits the same operational effects is included in the technical scope of the present invention.

Example

[0056] Hereinafter, the technical content of the present invention will be further described while giving examples of the present invention. The conditions in the examples shown below are example conditions adopted to confirm the feasibility and effects of the present invention, and the present invention is not limited to this example condition. Also, the present invention can adopt various conditions as long as it does not deviate from the gist of the present invention and achieves the object of the present invention.

[0057] Using the grain-oriented electrical steel sheet shown in Table 2 (described as "product sheet" in Table 2) manufactured from the steelmaking components shown in Table 1, the cores shown in Table 3 were created and the core characteristics were measured. Each core shown in Table 3 has four corner portions, and all four corner portions have the same shape. The details of the shape of each corner portion are shown in Table 3. The detailed manufacturing conditions and characteristics are shown in Tables 4 and 5. Note that the column of "steel type" in Table 2 is displayed in the format of "alphabet + number" (for example, A1, A2, etc.). The alphabet among these represents the steel type of the slab from which the steel type originated (the steel type in Table 1). Also, in the "Shape" column of Table 3, A represents the invariant type and B represents the variable type. The invariant type indicates that one corner portion is formed at a specific bending angle. The variable type indicates that steel plates bent at different bending angles are mixed in one corner portion. Furthermore, in the bending portion steel plate lamination pattern in Table 3, A represents the △L = T·tanθ pattern (Figure 7A) and B represents the △L = 0 pattern (Figure 7B).

[0058]

Table 1

[0059]

Table 2

[0060]

Table 3

[0061]

Table 4

[0062]

Table 5

[0063] (Directional Electromagnetic Steel Sheet) The magnetic properties of the directional electromagnetic steel sheet were measured based on the single sheet magnetic property test method (Single Sheet Tester: SST) specified in JIS C 2556:2015. As magnetic properties, the magnetic flux density B8(T) in the rolling direction of the steel sheet when excited at 800 A / m and further the iron loss at an AC frequency of 50 Hz and an excitation magnetic flux density of 1.7 T were measured. The magnetic properties are shown in Tables 1 and 2 together with the chemical composition. (Core) Using each steel plate as a raw material, cores a1 to h having the shapes shown in Table 3 were manufactured. Here, with reference to FIG. 8, the parameters used as the values defining the core shape in Table 3 will be described. L1' is the length of the inner surface side flat portion in one direction (X direction) in a side view in the winding axis direction (Y direction) of the wound core, and L2' is the length of the inner surface side flat portion in the other direction (Z direction) perpendicular to this. L3 is the stacking thickness of the wound core, L4 is the width of the stacked steel plates of the wound core, and the value of the distance L5 between the innermost flat portions uses the length of the flat portion between the bent portions of the innermost circumference. That is, even if the number of bent portions at the corner is two or more, the length of the flat portion between the bent portions is made the same length. Also, as the value of L5 when the number of bent portions is two or more, the length of the flat portion between the bent portions of the innermost steel plate corresponding to L0 in FIG. 7A is used. Also, in core h as shown in FIG. 7D, the value of L0 between the innermost bent portions is used as the value of L5. r is the inner surface side curvature radius of the bent portion on the inner surface side of the wound core, and φ is the bending angle of the bent portion of the wound core.

[0064] (Efficiency of the core) For the cores made of each steel plate, the no-load loss was determined, and the building factor (BF) was determined by taking the ratio to the magnetic properties of the material steel plates shown in Table 1. The results are shown in Tables 4 and 5. In this example, those with a BF of 1.12 or less were considered qualified. Examples Nos. 1 to No. 6 show the effects when the number of stacked sheets was reduced to increase the ratio of the length of the flat portion between the bent portions to 4 mm to 8 mm. Examples Nos. 1a to No. 6a show the effects when the ratio of the length of the flat portion between the bent portions was maintained high at 4 mm to 8 mm without reducing the number of stacked sheets. Examples Nos. 7 to No. 12 show the effects when the number of bent portions was increased to increase the ratio of the steel plates having a flat portion satisfying L = 3 to 8 mm. Examples Nos. 13 to No. 21 show the effects when the length of the flat portion between the bent portions was changed to 2 mm to 9 mm. Examples Nos. 22 to No. 28 show the effects when the number of bent portions was not changed, the stacking method of the steel plates was changed halfway, and the number of Ma was changed. Examples Nos. 29 to No. 40 show the effects when the shape of the core was changed.

[0065] From the results of Table 4 and Table 5, a wound core in which grain-oriented electromagnetic steel sheets are laminated in the plate thickness direction and which is substantially rectangular in side view, wherein the grain-oriented electromagnetic steel sheets have a flat portion and a bent portion continuously alternating in the longitudinal direction, the inner surface side curvature radius r of the bent portion in side view is 3 mm or less, the grain-oriented electromagnetic steel sheets contain Si: 2.0 to 7.0% by mass%, the balance being Fe and impurities, have a texture oriented in the Goss orientation, and in side view of the laminated grain-oriented electromagnetic steel sheets, in the circumferential direction of the wound core, a region where a bent portion having an angle of 10° or more and 80° or less and a flat portion having a length of 3 to 8 mm are continuously alternating is defined as region A, and when the number of grain-oriented electromagnetic steel sheets in which region A exists is Ma and the total number of laminated sheets is Mtotal, Ma / Mtotal ≧ 0.30 ·····(1) It has been clarified that the wound core of the present invention satisfying the above has high efficiency.

Explanation of Reference Numerals

[0066] 1 Grain-oriented electromagnetic steel sheet 1a Grain-oriented electromagnetic steel sheet before forming the bent portion 2 Laminated structure 3 Corner portion 4 Flat portion 5 Bent portion 6 Joint portion 7 Concave portion 10 Wound core body (wound core)

Claims

1. A wound core in which oriented electromagnetic steel sheets are laminated in the plate thickness direction and which is substantially rectangular in side view, wherein the oriented electromagnetic steel sheet has a flat portion and a bent portion continuously alternating in the longitudinal direction, the inner surface side curvature radius r in side view of the bent portion is 3 mm or less, the oriented electromagnetic steel sheet is by mass%, contains 2.0 to 7.0% of Si, and the balance consists of Fe and impurities and has a chemical composition, has an aggregate structure oriented in the Goss orientation, and in side view of the laminated oriented electromagnetic steel sheets, a region where a bent portion having an angle of 10° or more and 80° or less and a flat portion having a length of 3 to 8 mm are continuously alternating in the circumferential direction of the wound core is defined as region A, and when the number of oriented electromagnetic steel sheets in which this region A exists is Ma and the total number of laminated sheets is Mtotal, Ma / Mtotal ≥ 0.30 ······ (1) A wound core characterized by satisfying the above.

2. Among the wound cores of Claim 1, in region A where the circumferential length of the flat portion is the same, and in the oriented electromagnetic steel sheets different from each other, the flat portions in region A are laminated in parallel and continuously, when the bending angle of the bent portion in region A is Φ, the thickness in the direction perpendicular to the flat portion in the region where the flat portions are laminated in parallel and continuously is H, and the laminated thickness of the steel sheets laminated in this region is Lx, Lx / H / cosΦ: 0.97 to 1.03 ······ (2) A wound core characterized by satisfying the above.

3. Among the wound cores of Claim 1, at least two of the regions A have the flat portions of each region A laminated in parallel, the bending angle of the bent portion constituting the region A is Φ, the circumferential length of the flat portion arranged on the inner surface side of the core is Ln, Let the circumferential length of the flat portion disposed on the outer side of the iron core be Lm. When the distance between the two flat portions is further defined as Lh, Lm < Ln ······ (3) Lh / { (Ln - Lm) / 2} / tan Φ > 0.98 ······ (4) The wound iron core is characterized by satisfying the above conditions.

4. Among the wound iron cores of Claim 1, for at least two of the regions A, at least one of the flat portions of each region A is laminated in a non - parallel manner, Regarding the region A disposed on the inner side of the iron core, let the bending angle of the bent portion be Φn, the number of the bent portions be Rn, and the average circumferential length of the flat portion be Ln. Regarding the region A disposed on the outer side of the iron core, when the bending angle of the bent portion is Φm, the number of the bent portions is Rm, and the average circumferential length of the flat portion is Lm, Φm < Φn ······ (5) Rm > Rn ······ (6) Lm < Ln ······ (7) The wound iron core is characterized by satisfying the above conditions.

5. The wound iron core according to any one of Claims 1 to 4, wherein the laminated thickness L3 of the core is 16 mm or more.

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