Winded iron core, method for manufacturing wound iron core, and apparatus for manufacturing wound iron core.

Abstract

This invention relates to a wound iron core, a method for manufacturing a wound iron core, and an apparatus for manufacturing a wound iron core. The wound iron core (10) is characterized by the following: when the surface roughness of the steel plate portion along the direction connecting the center of the innermost directional electromagnetic steel plate (1) of the stacked directional electromagnetic steel plate (1) in the thickness direction of the wound iron core to the center of the outermost directional electromagnetic steel plate (1) in the thickness direction of the stacked directional electromagnetic steel plate (1) is set to Ral, and the surface roughness of the directional electromagnetic steel plate (1) in the direction parallel to the long side direction in the end face of the planar portion (4) of the stacked directional electromagnetic steel plate (1) is set to Rac, the ratio Ral / Rac satisfies the relationship 1.5 ≤ Ral / Rac ≤ 12.0.

Description

Technical Field

[0001] This invention relates to wound iron cores, a method for manufacturing wound iron cores, and an apparatus for manufacturing wound iron cores. This application claims priority to Japanese Patent Application No. 2020-178565, filed on October 26, 2020, the contents of which are incorporated herein by reference. Background Technology

[0002] Transformer cores can be laminated or wound. Generally, wound cores are manufactured by stacking directional electromagnetic steel sheets in layers, winding them into a ring (wound shape), and then pressing the wound to form a roughly square shape. (In this specification, wound cores manufactured in this way are sometimes referred to as box-type cores.) Due to this forming process, the directional electromagnetic steel sheets undergo mechanical processing strain (plastic deformation strain), which becomes a significant factor in greatly worsening the iron loss of the directional electromagnetic steel sheets. Therefore, strain-relief annealing is necessary.

[0003] On the other hand, as another manufacturing method for wound iron cores, patent documents 1 to 3 disclose techniques such as: pre-bending the steel plate portion at the corner of the wound iron core to form a relatively small bending area with a radius of curvature of 3 mm or less, and then stacking the bent steel plate to form a wound iron core (in this specification, the wound iron core manufactured in this way is sometimes referred to as a single core (UNICOA) (registered trademark)). According to this manufacturing method, the large-scale forming process as in the past is not required, the steel plate is precisely bent to maintain the shape of the iron core, and the processing strain is concentrated only in the bending portion (corner), so the strain removal based on the above-mentioned annealing process can be omitted, which has greater industrial advantages and has promoted its application.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2005-286169

[0007] Patent Document 2: Japanese Patent No. 6224468

[0008] Patent Document 3: Japanese Patent Application Publication No. 2018-148036 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] However, in unannealed single-core transformers, ferrite is exposed in the slits at the end faces of the stacked steel plates. Due to strain in these slits, the end faces heat up when manufacturing transformers using the core. This heating makes temperature control of the core and coils difficult. Therefore, attempts have been made to suppress temperature rise by immersing the core and coils in oil, or by using air circulation without oil immersion, even with cooling pipes. However, the temperature rise of the core and coils is significant, making temperature control still challenging.

[0011] The present invention was made in view of the above circumstances, and its object is to provide a wound iron core capable of reducing the temperature rise of the iron core and the coil, a method for manufacturing a wound iron core, and an apparatus for manufacturing a wound iron core.

[0012] Methods for solving problems

[0013] To achieve the above objectives, the present invention provides a wound iron core, which is a wound iron core having a rectangular hollow portion at its center and comprising a portion of directional electromagnetic steel sheets, with alternating flat and curved portions along its long side, stacked along the thickness direction. This wound iron core is formed by assembling the individually bent directional electromagnetic steel sheets into a wound shape, and multiple directional electromagnetic steel sheets are interconnected in each roll via at least one joint. The wound iron core is characterized in that the cross-section along the thickness direction of the directional electromagnetic steel sheets, i.e., along the long side direction… In the parallel L-section, when the surface roughness of the steel plate portion along the straight line connecting any point on the innermost circumference of the directional electromagnetic steel plate in the stacked directional electromagnetic steel plates to any point on the outermost circumference of the directional electromagnetic steel plate is defined as Ral, and the surface roughness of the steel plate portion along the straight line connecting any point on the end face of any sheet of the stacked directional electromagnetic steel plates in the thickness direction parallel to the aforementioned long side direction is defined as Rac, the ratio Ral / Rac satisfies the relationship 1.5≤Rl / Rac≤12.0. Furthermore, "the section along the thickness direction of the directional electromagnetic steel plate, i.e., the L-section parallel to the aforementioned long side direction" does not refer to the surface after the wound core has been cut, but rather to the end face of the wound core along the thickness direction of the directional electromagnetic steel plate and parallel to the long side direction of the directional electromagnetic steel plate. Surface roughness Ral can also be the surface roughness of the steel plate portion along the thickness direction of the directional electromagnetic steel sheet, and along the direction connecting the center of the innermost circumference of the directional electromagnetic steel sheet located in the thickness direction of the wound core and the center of the outermost circumference of the directional electromagnetic steel sheet in the thickness direction. Regarding surface roughness Rac, Rac can also be defined as the surface roughness of the directional electromagnetic steel sheet in the direction parallel to the long side of the end face of the planar portion of the stacked directional electromagnetic steel sheet.

[0014] Based on the practical situation that it is difficult to control the temperature of the core and coil when manufacturing a transformer by means of heat generated at the end face, even when immersed in oil, the inventors considered that if the surface area of ​​the L-section of the wound core can be increased with almost the same wound core volume, the contact area with oil or air can be increased, thereby improving the cooling efficiency. The inventors derived the following insight: If any one or more directional electromagnetic steel plates, each forming a corresponding layer, are laid along the entire length of the long side, and relative to the directional electromagnetic steel plates forming other layers, are perpendicular to the long side... By assembling the coiled core in a staggered manner along its width, the surface roughness Ral (the surface roughness of the steel plate along the straight line connecting any point on the innermost directional electromagnetic plate to any point on the outermost directional electromagnetic plate) of the L-section varies. This ensures that the surface roughness ratio Ral / Rac satisfies the relationship 1.5 ≤ Ral / Rac ≤ 12.0, effectively increasing the surface area of ​​the L-section of the coiled core. When using the coiled core (single core) as a transformer, this increases the contact area with oil or air, significantly improving cooling efficiency. Furthermore, when the surface roughness ratio Ral / Rac exceeds 12.0, the magnetic flux flow becomes unstable, and iron losses deteriorate. Here, the L-section of the coiled core does not refer to the surface that cuts off the coiled core, but rather to the end face of the coiled core along the thickness direction of the directional electromagnetic plate and parallel to the long side direction of the directional electromagnetic plate. Additionally, surface roughness Ral can be, for example, the surface roughness of the steel plate portion along the direction that connects the center of the thickness direction of the innermost directional electromagnetic steel plate with the center of the thickness direction of the outermost directional electromagnetic steel plate along the thickness direction of the directional electromagnetic steel plate.

[0015] Based on this understanding, in the above configuration of the present invention, the surface roughness ratio Ral / Rac satisfies the relationship 1.5≤Ral / Rac≤12.0, thus effectively reducing the temperature rise of the core and coil.

[0016] Furthermore, in the above configuration, the direction of the straight line connecting any point on the innermost directional electromagnetic steel plate and any point on the outermost directional electromagnetic steel plate can be arbitrarily set. Particularly preferred is a direction connecting the center of the innermost directional electromagnetic steel plate (located on the winding core) and the center of the outermost directional electromagnetic steel plate (located on the thickness direction) along the thickness direction of the directional electromagnetic steel plates. Additionally, as long as the relationship 1.5 ≤ Ral / Rac ≤ 12.0 is satisfied, the number of directional electromagnetic steel plates staggered in the width direction is arbitrary. For example, the directional electromagnetic steel plates can be staggered irregularly or regularly along the stacking direction. In the case of regular staggering, various methods can be considered, such as staggering the directional electromagnetic steel plates differently between adjacent layers, staggering every two layers, staggering every three layers, or staggering every other multiple layers. Furthermore, regarding the method of offsetting the directional electromagnetic steel plates in the width direction, one possible method is as follows: A guide member is provided that defines the positions of both ends of the directional electromagnetic steel plate in the width direction while guiding the directional electromagnetic steel plate in the long side direction. The directional electromagnetic steel plates are offset in the aforementioned width direction by changing the position of the guide member, but this method is not limited to this. Additionally, the surface roughness can be calculated, for example, based on the arithmetic mean roughness Ra specified in Japanese Industrial Standard JIS B 0601 (2013).

[0017] Furthermore, the present invention also provides a method for manufacturing a wound iron core, wherein the wound iron core is a wound shape having a rectangular hollow portion at the center and including a portion of directional electromagnetic steel plates with alternating flat and curved portions in the long side direction being stacked along the thickness direction. The wound iron core is formed by assembling the individually bent directional electromagnetic steel plates into a wound shape by stacking them in layers, and in each roll, multiple directional electromagnetic steel plates are interconnected via at least one joint. The method for manufacturing this wound iron core is characterized in that any one or more of the directional electromagnetic steel plates, which are stacked in such a way that each forms a corresponding layer, extend along the entire length of the directional electromagnetic steel plate in the long side direction, relative to the directional electromagnetic steel plates forming other layers, in relation to the aforementioned… The plates are assembled in a staggered manner along the width direction orthogonal to the long side. Thus, in the section along the thickness direction of the directional electromagnetic steel plate, i.e., the L section parallel to the long side direction, when the surface roughness of the steel plate portion along the straight line connecting any point on the innermost circumference of the directional electromagnetic steel plate in the stacked directional electromagnetic steel plate to any point on the outermost circumference of the directional electromagnetic steel plate is set as Ral, and the surface roughness of the steel plate portion along the straight line connecting any point on the end face in the thickness direction parallel to the long side direction of the stacked directional electromagnetic steel plate is set as Rac, the ratio Ral / Rac satisfies the relationship 1.5≤Ral / Rac≤12.0.

[0018] The above-described manufacturing method can also be characterized in that, in the end face of the wound core along the thickness direction of the directional electromagnetic steel plate and parallel to the long side direction of the directional electromagnetic steel plate, the surface roughness of the steel plate portion along the thickness direction of the directional electromagnetic steel plate, in the direction connecting the center of the thickness direction of the innermost circumference of the directional electromagnetic steel plate located in the thickness direction of the wound core and the center of the thickness direction of the outermost circumference of the directional electromagnetic steel plate located in the thickness direction of the wound core, is set to Ra1, and the end face of the planar portion of the stacked directional electromagnetic steel plate... When the surface roughness of the directional electromagnetic steel plate in the direction parallel to the long side is set as Rac, the directional electromagnetic steel plates are stacked to form a layer of the wound iron core of the present invention in such a way that the ratio of Ral to Rac, Ral / Rac, satisfies the relationship 1.5≤Ral / Rac≤12.0. Any one or more of the stacked directional electromagnetic steel plates are assembled such that they are staggered in the width direction orthogonal to the long side direction of the directional electromagnetic steel plates, covering the entire length of the long side direction.

[0019] Furthermore, the present invention also provides a winding core manufacturing apparatus comprising: a bending processing section for individually bending directional electromagnetic steel sheets; and an assembly section for forming a winding core by assembling the directional electromagnetic steel sheets individually bent by the bending processing section into a winding shape in a layered manner. The winding core is a winding shape in which multiple directional electromagnetic steel sheets are interconnected via at least one joint in each roll, and has a rectangular hollow portion at the center, and includes portions of directional electromagnetic steel sheets with alternating flat and curved portions along the long side direction, which are stacked along the thickness direction. The assembly section assembles one or more directional electromagnetic steel sheets stacked in a manner that forms a corresponding layer, extending along the entire length of the directional electromagnetic steel sheet in the long side direction, staggered relative to the directional electromagnetic steel sheets forming other layers in a width direction orthogonal to the long side direction, thereby achieving a thickness ratio along the thickness of the directional electromagnetic steel sheets. In the L-section, which is parallel to the aforementioned long side direction, when the surface roughness of the steel plate portion along the straight line connecting any point on the innermost circumference of the directional electromagnetic steel plate in the stacked directional electromagnetic steel plates to any point on the outermost circumference of the directional electromagnetic steel plate is set as Ral, and the surface roughness of the steel plate portion along the straight line connecting any point on the end face in the thickness direction parallel to the aforementioned long side direction in any one of the stacked directional electromagnetic steel plates is set as Rac, the ratio Ral / Rac satisfies the relationship 1.5≤Rl / Rac≤12.0, and the assembly part is equipped with a guide member that guides the directional electromagnetic steel plate in the long side direction while defining the positions of both ends of the directional electromagnetic steel plate in the width direction, and the directional electromagnetic steel plates are offset in the width direction by changing the position of the guide member.

[0020] The aforementioned winding core manufacturing apparatus can also use a winding core manufacturing method. This apparatus includes: a bending processing section for individually bending directional electromagnetic steel sheets; and an assembly section for forming a winding core by assembling the directional electromagnetic steel sheets individually bent by the bending processing section into a winding shape. The winding core is formed by connecting multiple directional electromagnetic steel sheets to each other via at least one joint in each roll, and includes a portion where directional electromagnetic steel sheets with alternating flat and curved portions in the long side direction are stacked along the thickness direction to form a winding core with a rectangular hollow portion at the center. The assembly section includes a guide member that defines the positions of both ends of the directional electromagnetic steel sheets in the width direction while guiding the directional electromagnetic steel sheets in the long side direction. The assembly section is configured to, on the end face of the winding core parallel to the long side direction of the directional electromagnetic steel sheets along the thickness direction, when... The surface roughness of the steel plate portion in the direction connecting the center of the innermost circumference of the directional electromagnetic steel plate located along the thickness direction to the center of the outermost circumference of the directional electromagnetic steel plate located along the thickness direction of the wound iron core is set as Ral. When the surface roughness of the directional electromagnetic steel plate in the end face of the planar portion of the stacked directional electromagnetic steel plates in the direction parallel to the long side direction is set as Rac, the ratio of Ral to Rac, Ral / Rac, satisfies the relationship 1.5≤Ral / Rac≤12.0. The directional electromagnetic steel plates are stacked to form a layer of the wound iron core. By changing the position of the guide, any one or more of the stacked directional electromagnetic steel plates are assembled such that they are offset in the width direction orthogonal to the long side direction, covering the entire length of the long side direction, relative to the directional electromagnetic steel plates forming other layers.

[0021] According to this method and apparatus for manufacturing a wound iron core, similar to the wound iron core described above, the surface roughness ratio Ral / Rac satisfies the relationship 1.5≤Ral / Rac≤12.0, thus effectively reducing the temperature rise of the iron core and the coil.

[0022] The effects of the invention

[0023] According to the present invention, since the surface roughness ratio Ral / Rac satisfies the relationship 1.5≤Ral / Rac≤12.0, the temperature rise of the iron core and the coil can be effectively reduced. Attached Figure Description

[0024] Figure 1 This is a perspective view schematically illustrating a wound iron core according to one embodiment of the present invention.

[0025] Figure 2 yes Figure 1 The side view of the wound iron core shown in the embodiment.

[0026] Figure 3 This is a side view schematically illustrating another embodiment of the present invention of a wound iron core.

[0027] Figure 4 This is a side view schematically representing an example of a single layer of directional electromagnetic steel sheet that constitutes a wound iron core.

[0028] Figure 5 This is a side view schematically representing another example of a single layer of directional electromagnetic steel sheet that constitutes a wound iron core.

[0029] Figure 6 This is a side view schematically showing an example of a bent portion of the directional electromagnetic steel sheet constituting the wound core of the present invention.

[0030] Figure 7 (a) is a longitudinal end view showing an example of setting a straight line that specifies the surface roughness Ral of the end face of the stacked structure of the wound iron core formed by stacking directional electromagnetic steel sheets, and (b) is a side end view showing an example of setting a straight line that specifies the surface roughness Rac on the end face of any one of the directional electromagnetic steel sheets that is parallel to the long side direction and along the thickness direction.

[0031] Figure 8 This is a cross-sectional view of a directional electromagnetic steel sheet stacked with a wound iron core, parallel to the width direction and along the thickness direction. Figure 1 (End view of the cut section of line AA).

[0032] Figure 9 It is a block diagram of the structure of a winding iron core manufacturing device that roughly forms a single core on the ground.

[0033] Figure 10 It is a schematic three-dimensional diagram of the transformer body, that is, the wound iron core around which the coils are wound.

[0034] Figure 11 This is a simplified representation of an assembly section equipped with guides that offset the directional electromagnetic steel sheets supplied from the bending section in the width direction. Figure 9 A three-dimensional view of the manufacturing equipment.

[0035] Figure 12 This is a schematic diagram showing the dimensions of the wound iron core manufactured during the performance evaluation. Detailed Implementation

[0036] 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, the lower and upper limits of the numerical ranges described below are included within the ranges. Values ​​expressed as "more than" or "less than" are not included in the numerical ranges. Additionally, "%" related to chemical composition, unless otherwise specified, refers to "mass %".

[0037] Furthermore, terms used in this specification to define shape, geometric conditions, and their degree, such as "parallel," "perpendicular," "identical," and "right angle," as well as values ​​for length and angle, are not limited to their precise meanings but are interpreted to include the range of degrees to which the same function can be expected.

[0038] In addition, in this specification, "directional electromagnetic steel plate" is sometimes simply referred to as "steel plate" or "electromagnetic steel plate", and "wound iron core" is sometimes simply referred to as "iron core".

[0039] One embodiment of the present invention provides a wound core having a generally rectangular core body in side view. This core body includes a portion of directional electromagnetic steel sheets, in which planar portions and curved portions are continuously stacked in the thickness direction, having a generally polygonal stacked structure in side view. Here, the planar portion refers to the straight portion other than the curved portion. The aforementioned directional electromagnetic steel sheet, as an example, has a chemical composition containing 2.0 to 7.0% Si by mass, with the remainder consisting of Fe and impurities, and has a structure oriented according to the Goss orientation. For example, directional electromagnetic steel strip as described in JIS C 2553:2019 can be used as the directional electromagnetic steel sheet.

[0040] Next, the shapes of the wound iron core and the directional electromagnetic steel plate according to one embodiment of the present invention will be specifically described. The shapes of the wound iron core and the directional electromagnetic steel plate described herein are not particularly novel, but merely conform to known shapes of wound iron cores and directional electromagnetic steel plates.

[0041] 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. Additionally, Figure 3 This is a side view schematically illustrating another embodiment of the wound iron core.

[0042] Furthermore, in this invention, "side view" refers to the view along the width direction of the elongated directional electromagnetic steel plate constituting the wound core. Figure 1(Observed along the Y-axis). A side view is a diagram showing the shape as visually confirmed by looking from the side. Figure 1 (Graph of the Y-axis direction).

[0043] One embodiment of the present invention provides a wound core body that is generally polygonal in shape when viewed from the side. This wound core body 10 has a stacked structure in which directional electromagnetic steel plates 1 are stacked along the thickness direction, and are generally rectangular in shape when viewed from the side. This wound core body 10 can be used directly as a wound core, and, if necessary, can be equipped with known fastening tools such as binding straps to secure the stacked multiple directional electromagnetic steel plates together. Furthermore, the surface roughness described later refers to a value measured for the wound core body excluding binding straps.

[0044] In this embodiment, the core length of the wound core body 10 is not particularly limited. As long as the number of bends 5 is the same, even if the core length varies in the wound core body 10, the volume of the bends 5 remains constant, and therefore the iron loss generated in the bends 5 is also constant. The longer the core length, the smaller the volume fraction of the bends 5 relative to the wound core body 10, and therefore the smaller the impact on iron loss deterioration. Therefore, the core length of the wound core body 10 is preferably relatively long. The core length of the wound core body 10 is preferably 1.5 m or more, more preferably 1.7 m or more. In addition, in this invention, the core length of the wound core body 10 refers to the circumference at the center point of the stacking direction of the wound core body 10 when viewed from the side.

[0045] Such wound iron cores can be used well in any of the previously known applications.

[0046] The core of this embodiment is characterized by being approximately polygonal in side view. In the following description using the accompanying drawings, for simplicity of illustration and explanation, a generally rectangular (quadrilateral) core will be used. However, cores of various shapes can be manufactured depending on the angle and number of the bends 5 and the length of the flat sections. For example, if all the bends 5 have an angle of 45° and the flat sections 4 have equal lengths, the core will be octagonal in side view. Conversely, if the angle is 60°, there are six bends 5, and the flat sections 4 have equal lengths, the core will be hexagonal in side view.

[0047] like Figure 1 as well as Figure 2As shown, the wound core body 10 is a directional electromagnetic steel plate 1 with alternating continuous planar portions 4, 4a and curved portions 5 along its long side. It includes portions stacked along the plate thickness direction and, when viewed from the side, has a generally rectangular stacked structure 2 with a hollow portion 15. The corner portion 3, including the curved portions 5, has two or more curved portions 5 with a curved shape when viewed from the side, and the sum of the bending angles of the curved portions 5 present in one corner portion 3 is, for example, 90°. The corner portion 3 has a planar portion 4a shorter than the planar portion 4 between adjacent curved portions 5, 5. Thus, the corner portion 3 has two or more curved portions 5 and one or more planar portions 4a. Furthermore, Figure 2 The implementation method is that one of the curved portions 5 is 45°. Figure 3 The implementation method is that one of the bending portions 5 is 30°.

[0048] As these examples illustrate, the wound core of this embodiment can be composed of bends 5 with various angles. However, from the viewpoint of suppressing iron loss by suppressing strain caused by deformation during processing, the bending angles φ (φ1, φ2, φ3) of the bends 5 are preferably 60° or less, and more preferably 45° or less. The bending angles φ of the bends in a core can be arbitrarily configured. For example, φ1 = 60° and φ2 = 30° can be set. From the viewpoint of production efficiency, the bending angles are preferably equal. If reducing a certain number of deformed parts can reduce the iron loss of the manufactured core compared to the iron loss of the steel plate used, a combination of different angles can also be used. The design can be arbitrarily selected based on the points of emphasis in core processing.

[0049] Reference Figure 6 The curved portion 5 will be described in more detail. Figure 6 This diagram schematically illustrates an example of a curved portion (curved section) 5 of a directional electromagnetic steel sheet 1. The bending angle of the curved portion 5 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 in the bending direction. On the outer surface of the directional electromagnetic steel sheet 1, this is represented by the supplementary angle φ formed by extending the straight sections of the plane portions 4 and 4a on both sides of the curved portion 5 (i.e., the straight sections). At this point, the point where the extended straight lines detach from the steel sheet surface is such that the boundary between the plane portion 4 and the curved portion 5 on the outer surface of the steel sheet is... Figure 6 Points F and G are in the middle.

[0050] 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 respectively. Points E and D are the boundaries between the flat portion 4 and the curved portion 5 on the inner surface of the steel plate. Here, when connecting points A and B with a straight line, the intersection point on the arc DE on the inner side of the curved portion of the steel plate is designated as C.

[0051] Then, in this invention, the curved portion 5 refers to the part of the directional electromagnetic steel plate 1 surrounded by the aforementioned points D, E, F, and G when viewed from the side. Figure 6 In the diagram, the surface of the steel plate between point D and point E, i.e., the inner surface of the bent portion 5, is denoted as La, and the surface of the steel plate between point F and point G, i.e., the outer surface of the bent portion 5, is denoted as Lb. Furthermore, in the wound core of the present invention, the radius of curvature of each bent portion 5 of each directional electromagnetic steel plate 1 stacked along the thickness direction is not particularly limited.

[0052] Furthermore, there are no particular limitations on the method for measuring the radius of curvature r of the curved portion 5, but it can be measured, for example, by observing it at 200x magnification using a commercially available microscope (Nikon ECLIPSE LV150). Specifically, the curvature center point A is determined based on the observation results, but as a method of determination, for example, if the intersection point after extending line segment EF and line segment DG inwards to the opposite side of point B is defined as A, then the magnitude of the radius of curvature r corresponds to the length of line segment AC.

[0053] Figure 4 as well as Figure 5 This is a schematic diagram illustrating an example of a directional electromagnetic steel sheet 1 wound in one layer around a core body 10. Figure 4 as well as Figure 5 In the example, the directional electromagnetic steel plate 1 used is bent to achieve a single-core wound iron core, having two or more bent portions 5 and a flat portion 4, and forming a ring that is approximately polygonal in side view through the end face of the long side direction of the directional electromagnetic steel plate 1, i.e., the joint portion 6 (gap).

[0054] In this embodiment, the wound core body 10 as a whole only needs to have a layered structure that is approximately polygonal in side view. It can be as follows: Figure 4 As shown in the example, the core body 10 can be wound in one layer by a single directional electromagnetic steel sheet via a joint 6 (one directional electromagnetic steel sheet is connected to each roll via a joint 6), or as shown in the example. Figure 5 As shown in the example, one directional electromagnetic steel plate 1 constitutes approximately half a turn of the wound core, and two directional electromagnetic steel plates 1 constitute one layer of the wound core body 10 via two joints 6 (the two directional electromagnetic steel plates are connected to each other in each roll via two joints 6).

[0055] 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, etc., but it is usually in the range of 0.15mm to 0.35mm, preferably in the range of 0.18mm to 0.27mm.

[0056] Furthermore, the method for manufacturing the directional electromagnetic steel sheet 1 is not particularly limited, and conventionally known methods for manufacturing directional electromagnetic steel sheets can be appropriately selected. A preferred specific example of the manufacturing method is as follows: a slab with a C content of 0.04 to 0.1% by mass and other chemical compositions as described above for directional electromagnetic steel sheets is heated to 1000°C or higher and hot-rolled; then, the hot-rolled sheet is annealed as needed; subsequently, it is cold-rolled once or twice or more with intermediate annealing to obtain a cold-rolled steel sheet; the cold-rolled steel sheet is then heated to 700 to 900°C in, for example, a wet hydrogen-inert gas environment for decarburization annealing; further nitriding annealing is performed as needed; after coating with an annealing separating agent, a final annealing is performed at approximately 1000°C; and an insulating film is formed at approximately 900°C. Furthermore, subsequent coatings for adjusting the coefficient of kinetic friction can also be applied.

[0057] Furthermore, generally speaking, even steel plates that have undergone a process known as "magnetic domain control" using strain, grooves, etc., during the steel plate manufacturing process can achieve the effects of the present invention.

[0058] Furthermore, in this embodiment, the wound core 10, composed of directional electromagnetic steel sheets 1 having the above-described manner, is formed by assembling individually bent directional electromagnetic steel sheets 1 into a wound shape through layered stacking. Multiple directional electromagnetic steel sheets 1 are interconnected in each roll via at least one joint 6. The cross-section along the thickness direction T of the directional electromagnetic steel sheet 1, i.e., the L-section parallel to the long side direction L (X direction) (see reference...) Figure 7 In (a)), when the surface roughness of the steel plate portion along the straight line L1 connecting any point P1 on the innermost circumference of the directional electromagnetic steel plate 1a in the coiled shape and any point P2 on the outermost circumference of the directional electromagnetic steel plate 1b is set as Ra1, in any one of the directional electromagnetic steel plates 1, along the end face (refer to) along the plate thickness direction T parallel to the long side direction L, Figure 7When the surface roughness of the steel plate portion of the straight line L2 formed by connecting any points P3 and P4 on (b) side end view) is set as Rac, its ratio Ral / Rac satisfies the relationship 1.5≤Ral / Rac≤12.0. Here, "the section along the thickness direction T, i.e., the L section parallel to the long side direction L (X direction)" does not refer to the surface after the wound core 10 is cut off, but rather to the end face of the wound core 10 along the thickness direction T of the directional electromagnetic steel plate 1 and parallel to the long side direction of the directional electromagnetic steel plate 1. The surface roughness Ral is preferably the surface roughness of the steel plate portion along the thickness direction T of the directional electromagnetic steel plate 1 and along the direction L1a connecting the center P1a of the thickness direction of the innermost directional electromagnetic steel plate 1a and the center P2a of the thickness direction T of the outermost directional electromagnetic steel plate 1b. The surface roughness Ral can be, for example, the average value obtained by measuring five points where the planar portion 4 of the directional electromagnetic steel plate 1a is equally divided along its long side. Regarding the surface roughness Rac, since the deviation in surface roughness along the long side of the directional electromagnetic steel plate is small, any one of the directional electromagnetic steel plates can be selected for measurement. However, for example, three directional electromagnetic steel plates can be suspended for measurement, and the average value of these measurements can be obtained. The surface roughness Rac can also be the surface roughness in the direction parallel to the long side of the end face of the planar portion 4 of the directional electromagnetic steel plate 1 (the end face of the planar portion 4 parallel to the long side).

[0059] In this embodiment, to ensure the surface roughness ratio satisfies the following relationship, the directional electromagnetic steel plates 1 are stacked such that each plate forms a corresponding layer (a layer wound around the iron core), and one or more of the stacked directional electromagnetic steel plates 1 extend along the entire length of their long side direction L, and are assembled in a way that they are staggered relative to the directional electromagnetic steel plates 1 forming other layers in the width direction C, which is orthogonal to the long side direction L. Specifically, in this embodiment, as... Figure 8 (The C-end face parallel to the width direction; along) Figure 1 As shown in the cross-sectional end view of line AA, the directional electromagnetic steel plates 1 are assembled in a manner that is staggered from each other in the width direction C (Y direction) between adjacent layers. Here, the straight line L1 used to specify the surface roughness Ral can extend parallel to the stacking direction of the directional electromagnetic steel plates 1, but it can also be as follows: Figure 7 As shown in (a), it is inclined relative to the vertical direction. The straight line L1 used to specify the surface roughness Ral preferably extends parallel to the stacking direction of the directional electromagnetic steel sheet 1. The straight line L2 used to specify the surface roughness Rac can extend perpendicularly to the stacking direction of the directional electromagnetic steel sheet 1, but it can also extend as shown in (a). Figure 7As shown in (b), it is inclined relative to the vertical direction. The straight line L2 used to define the surface roughness Rac preferably extends perpendicularly along the stacking direction of the directional electromagnetic steel plate 1. In addition, the surface roughness Ral and Rac can be calculated, for example, based on the arithmetic mean roughness Ra specified by Japanese Industrial Standard JIS B 0601 (2013), especially in this embodiment, when the coil 75 is wound around the iron core 10. Figure 10 In the shown state, the surface roughness Ral and Rac are measured on the upper surface (end face and L-section) 10a of the iron core 10, for example, using a digital microscope (KEYENCE VHX-7000). Specifically, the magnification is set so that the L-end face of the outermost circumferential directional electromagnetic steel plate 1b and the L-end face of the innermost circumferential directional electromagnetic steel plate 1a are both within the field of view, and the digital microscope is positioned along the straight lines L1 and L2 (refer to...). Figure 7 The measurement is performed by scanning. In this case, the removal of the roughness curve can be appropriately set. When measuring the arithmetic mean roughness Ra by a digital microscope, the removal value λs = 0 μm and the removal value λc = 0 mm can be set for vibration correction before measurement. The measurement magnification is preferably 100x or more, more preferably 500x to 700x. When the arithmetic mean roughness Ra is set, the surface roughness Raal can be, for example, 0.6 to 14.4 μm, and the surface roughness Rac can be, for example, 0.5 to 1.2 μm.

[0060] In addition, Figure 9 The diagram below roughly represents a device capable of manufacturing a wound iron core like the one described above. Figure 9 A manufacturing apparatus 70 for a single-core wound iron core is schematically shown. The manufacturing apparatus 70 includes: a bending processing section 71 for individually bending directional electromagnetic steel plates 1; and an assembly section 72 for assembling the directional electromagnetic steel plates 1, which are individually bent by the bending processing section 71, into a wound shape by stacking them in layers, thereby forming a wound iron core with a wound shape. The wound iron core includes a portion of directional electromagnetic steel plates 1 that are connected to each other by at least one joint and whose flat portion 4 and curved portion 5 are continuously stacked in the thickness direction, forming a wound iron core with a rectangular hollow portion at the center.

[0061] The directional electromagnetic steel sheet 1 is supplied to the bending processing section 71 at a predetermined conveying speed from the steel sheet supply section 90, which holds the annular strip formed by winding the directional electromagnetic steel sheet 1 into a roll. The directional electromagnetic steel sheet 1 supplied in this way is suitably cut to appropriate dimensions in the bending processing section 71, and is bent individually in small batches of one sheet at a time.

[0062] Here, as described above, in order to satisfy the surface roughness ratio Ral / Rac of 1.5 ≤ Ral / Rac ≤ 12.0, the assembly unit 72 stacks the directional electromagnetic steel plates 1 in such a way that each plate forms a corresponding layer (a layer of the wound iron core), and by changing the position of the guide member 95 in the width direction, the stacked directional electromagnetic steel plates 1 are arranged such that any one or more of them extend along the entire length of their long side direction L, and are staggered relative to the directional electromagnetic steel plates 1 forming other layers in the width direction C, which is orthogonal to the long side direction L. Especially in this embodiment, as... Figure 11 As shown, the assembly section 72 has multiple guides 95 on the steel plate receiving section 97. These guides 95 define the positions of both ends of the directional electromagnetic steel plate 1 in the width direction C and guide the directional electromagnetic steel plate 1 along the long side direction L. By changing the position of the guides 95 in the width direction C, the directional electromagnetic steel plates 1 supplied from the bending processing section 71 are offset in the width direction C. Therefore, it is possible to assemble the directional electromagnetic steel plates 1 in such a way that any one or more of the stacked directional electromagnetic steel plates 1 are spread along their entire long side direction, offset from the directional electromagnetic steel plates 1 forming other layers in the width direction C, which is orthogonal to the long side direction. Specifically, whenever one directional electromagnetic steel plate 1 is stacked, the guides 95 protrude from other offset positions in the width direction C, causing the portions of subsequent directional electromagnetic steel plates 1 to be offset in the width direction C.

[0063] Next, the following presents actual verification data on the suppression of temperature rise in the wound core 10 and the coil wound thereon of this embodiment, which are configured as described above.

[0064] In obtaining actual verification data, the inventors manufactured products with the specifications shown in Table 1 using various steel plates as raw materials. Figure 12 The iron cores a to d are shown in the diagram.

[0065] In addition, L1 is the distance between mutually parallel grain-oriented electrical steel sheets 1 located at the innermost periphery of the wound core (distance between inner surface side flat portions) in a flat cross-section parallel to the X-axis direction and including the center CL. L2 is the distance between mutually parallel grain-oriented electrical steel sheets 1 located at the innermost periphery of the wound core (distance between inner surface side flat portions) in a longitudinal cross-section parallel to the Z-axis direction and including the center CL. L3 is the laminated thickness of the wound core (thickness in the lamination direction) in a flat cross-section parallel to the X-axis direction and including the center CL. L4 is the width of the laminated steel sheets of the wound core in a flat cross-section parallel to the X-axis direction and including the center CL. L5 is the distance between flat portions (distance between bent portions) that are adjacent to each other at the innermost part of the wound core and arranged such that they form a right angle when combined. In other words, L5 is the length in the long-side direction of the shortest flat portion 4a among the flat portions 4 and 4a of the grain-oriented electrical steel sheet at the innermost periphery. r is the curvature radius of the bent portion 5 on the inner surface side of the wound core. φ is the bending angle of the bent portion 5 of the wound core. The structure of the approximately rectangular iron core Nos. a to d in Table 1 is as follows: the flat portion with inner surface side flat portion distance L1 is divided at approximately the center of the distance L1, and two iron cores having a substantially U-shape are combined.

[0066] Herein, the iron core of core No. c is a so-called box-type wound core with a curvature radius of 25 mm that has been generally used as a conventional wound core. It is manufactured by the following method: after shearing a steel sheet and winding it into a cylindrical shape, the cylindrical laminate is kept as it is, and the corner portions are pressed to have a constant curvature, thereby forming a substantially rectangular shape. In addition, the iron core of core No. d is a single-core type wound core having three bent portions 5 at one corner portion 3 with a curvature radius r of 1 mm; the iron core of core No. a is a single-core type wound core having two bent portions 5 at one corner portion 3 with a curvature radius r of 1 mm; and the iron core of core No. b is a single-core type wound core having a considerably larger curvature radius r (curvature radius r of 20 mm) compared with the iron cores of core Nos. a and d.

[0067]

Table 1

[0068]

[0069] Tables 2A and 2B show the surface roughness ratios Ral / Rac obtained by measuring 58 examples of raw materials with different steel plate thicknesses (mm) based on various core shapes as described above. The temperature rise ΔT (°C) of the core and coil was measured and evaluated. Furthermore, the surface roughness Ral and Rac used in the Ral / Rac calculation are both arithmetic mean roughness Ra measured using a digital microscope (KEYENCE VHX-7000). The arithmetic mean roughness Ra was measured according to JIS B 0601 (2013). Vibration correction was performed by setting the removal values ​​to λs = 0 and λc = 0. The measurement magnification was 500 to 700x.

[0070] In the evaluation of temperature rise, it is planned to wind coil 75 on iron core 10. Figure 10 The component shown was immersed in oil and operated at a load rate of 40% and a magnetic flux density of 1.7T for 72 hours. The oil temperature was then measured, and the temperature rise (temperature after 2 hours - initial temperature) was evaluated. A temperature below 6.6 degrees Celsius was considered acceptable.

[0071] Table 2A

[0072]

[0073]

[0074] Table 2B

[0075]

[0076]

[0077] As can be seen from Tables 2A and 2B, for all cores No. a, b, c, and d, regardless of their plate thickness, as long as the surface roughness ratio Ral / Rac is within the range of 1.5 ≤ Ral / Rac ≤ 12.0, the temperature rise ΔT (°C) of the core and coil is suppressed to below 6.6°C, with a few exceptions.

[0078] Based on the above results, the directional electromagnetic steel plates 1 of the present invention are assembled in a way that is staggered in the width direction, thereby increasing the surface area of ​​the L-section and changing the surface roughness Ral of the L-section of the wound core. As a result, the surface roughness ratio Ral / Rac satisfies the relationship 1.5≤Ral / Rac≤12.0, thus it becomes clear that the temperature rise of the core and the coil can be effectively reduced.

[0079] (Postscript)

[0080] The wound iron core, the method for manufacturing the wound iron core, and the apparatus for manufacturing the wound iron core according to the above embodiments can be mastered as follows.

[0081] (1) The wound core of the present invention is a wound core having a rectangular hollow portion at the center, and comprising a portion of directional electromagnetic steel plates, which are continuously stacked along the thickness direction with alternating planar portions and curved portions in the long side direction. This wound core is formed by assembling the individually bent directional electromagnetic steel plates into a wound shape by stacking them in layers, and multiple directional electromagnetic steel plates are interconnected in each roll via at least one joint. The wound core is characterized in that…

[0082] In the section along the thickness direction of the aforementioned directional electromagnetic steel sheet, i.e., section L parallel to the aforementioned long side direction, when the surface roughness of the steel plate portion along the straight line connecting any point on the innermost circumference of the directional electromagnetic steel sheet in the stacked directional electromagnetic steel sheet to any point on the outermost circumference of the directional electromagnetic steel sheet is defined as Ral, and the surface roughness of the steel plate portion along the straight line connecting any points on the end face in the thickness direction parallel to the aforementioned long side direction of any one of the stacked directional electromagnetic steel sheets is defined as Rac, the ratio Ral / Rac satisfies the relationship 1.5 ≤ Ral / Rac ≤ 12.0.

[0083] (2) The method for manufacturing the wound core of the present invention is as follows: the wound core has a rectangular hollow portion at the center, and includes a portion of directional electromagnetic steel plates with alternating flat and curved portions in the long side direction being stacked along the plate thickness direction. The wound core is formed by assembling the aforementioned directional electromagnetic steel plates, which have been individually bent, into a wound shape by stacking them in layers, and in each roll, multiple directional electromagnetic steel plates are connected to each other via at least one joint. The method for manufacturing the wound core is characterized in that...

[0084] One or more of the aforementioned directional electromagnetic steel plates, which are stacked in a manner that forms a corresponding layer, are arranged along their entire length along their long side. These plates are staggered relative to the directional electromagnetic steel plates forming other layers in a width direction orthogonal to the long side. Thus, in a section along the thickness direction of the directional electromagnetic steel plate (i.e., section L parallel to the long side), when the surface roughness of the steel plate portion along a straight line connecting any point on the innermost circumference of the stacked directional electromagnetic steel plate with any point on the outermost circumference is defined as Ral, and the surface roughness of the steel plate portion along a straight line connecting any points on the end face in the thickness direction parallel to the long side of the stacked directional electromagnetic steel plate is defined as Rac, the ratio Ral / Rac satisfies the relationship 1.5 ≤ Ral / Rac ≤ 12.0.

[0085] The winding core manufacturing apparatus of the present invention comprises:

[0086] The bending processing section performs bending processing on the directional electromagnetic steel sheet separately; and

[0087] The assembly section forms a wound core by stacking the directional electromagnetic steel sheets, which have been individually bent by the bending section, in layers. This wound core consists of multiple directional electromagnetic steel sheets connected to each other via at least one joint in each roll, and includes a portion where directional electromagnetic steel sheets with alternating flat and curved portions along the long side are stacked along the thickness direction, forming a wound core with a rectangular hollow portion at the center.

[0088] The aforementioned assembly involves assembling one or more directional electromagnetic steel sheets, each forming a corresponding layer, along their entire length along their long side. These sheets are staggered relative to the directional electromagnetic steel sheets forming other layers in a width direction orthogonal to the long side. This results in a cross-section along the thickness direction of the directional electromagnetic steel sheets, specifically a section L parallel to the long side. The surface roughness of the steel sheet portion along the straight line connecting any point on the innermost circumference of the directional electromagnetic steel sheet in the coiled shape to any point on the outermost circumference is achieved. The roughness is set as Ral, and the surface roughness of the steel plate portion along a straight line connecting any point on the end face parallel to the plate thickness direction in the stacked directional electromagnetic steel plates is set as Rac. The ratio Ral / Rac satisfies the relationship 1.5≤Ral / Rac≤12.0. The assembly part is equipped with a guide member that guides the directional electromagnetic steel plates in the long side direction while defining the positions of both ends in the width direction. By changing the position of the guide member, the directional electromagnetic steel plates are offset in the width direction.

[0089] Explanation of symbols

[0090] 1. Directional Electromagnetic Steel Sheet

[0091] 4. Planar section

[0092] 5. Bending section

[0093] 6. Joint

[0094] 10. Winded iron core (wound iron core body)

Claims

1. A wound iron core having a rectangular hollow portion at its center, and comprising a portion of directional electromagnetic steel plates, in which planar portions and curved portions are continuously stacked along the thickness direction, in a wound shape. The wound core is formed by assembling individually bent directional electromagnetic steel sheets into a wound shape, and multiple directional electromagnetic steel sheets are connected to each other through at least one joint in each roll. The aforementioned wound iron core is characterized by, In the end face of the wound iron core along the thickness direction of the aforementioned directional electromagnetic steel plate and parallel to the long side direction of the aforementioned directional electromagnetic steel plate, When along the aforementioned plate thickness direction The surface roughness of the steel plate portion along the direction connecting the center of the innermost circumference of the directional electromagnetic steel plate of the stacked directional electromagnetic steel plates in the thickness direction with the center of the outermost circumference of the directional electromagnetic steel plate of the wound core in the thickness direction is defined as Ral. When the surface roughness of the directional electromagnetic steel sheet in the direction parallel to the long side direction of the end face of the planar portion of the stacked directional electromagnetic steel sheet is set as Rac, The ratio of Ral to Rac, Ral / Rac, satisfies the relationship 1.5 ≤ Ral / Rac ≤ 12.

0.

2. A method for manufacturing a wound iron core, The aforementioned wound core is a wound core with a rectangular hollow portion at the center, and includes a portion of directional electromagnetic steel plates that are continuously stacked along the thickness direction, with alternating flat and curved portions along the long side. The wound core is formed by assembling individually bent directional electromagnetic steel sheets into a wound shape, and multiple directional electromagnetic steel sheets are connected to each other through at least one joint in each roll. The aforementioned method for manufacturing a wound iron core is characterized by the following: The aforementioned directional electromagnetic steel plates are stacked in such a way that each forms a layer of the aforementioned wound iron core, and any one or more of the stacked directional electromagnetic steel plates are assembled such that, along the entire length of the long side, they are offset relative to the directional electromagnetic steel plates forming the other layers in a width direction orthogonal to the aforementioned long side direction. So that in the end face of the wound iron core along the thickness direction of the aforementioned directional electromagnetic steel plate and parallel to the long side direction of the aforementioned directional electromagnetic steel plate, When along the aforementioned plate thickness direction The surface roughness of the steel plate portion along the direction connecting the center of the innermost circumference of the directional electromagnetic steel plate of the stacked directional electromagnetic steel plates in the thickness direction with the center of the outermost circumference of the directional electromagnetic steel plate of the wound core in the thickness direction is defined as Ral. When the surface roughness of the directional electromagnetic steel sheet in the direction parallel to the long side direction of the end face of the planar portion of the stacked directional electromagnetic steel sheet is set as Rac, The ratio of Ral to Rac, Ral / Rac, satisfies the relationship 1.5 ≤ Ral / Rac ≤ 12.

0.

3. A winding iron core manufacturing apparatus, characterized in that, have: The bending processing section performs bending processing on the directional electromagnetic steel sheet separately; and The assembly section forms a wound core by assembling the directional electromagnetic steel sheets, which have been individually bent by the bending section, into a coiled shape. This coiled core consists of multiple directional electromagnetic steel sheets connected to each other via at least one joint in each coil, and includes a portion where directional electromagnetic steel sheets with alternating flat and curved portions along the long side are stacked along the thickness direction, forming a coiled core with a rectangular hollow portion at the center. The assembly section includes a guide that defines the positions of both ends of the directional electromagnetic steel plate in the width direction and guides the directional electromagnetic steel plate in the long side direction. The above assembly part is, The aforementioned directional electromagnetic steel plates are stacked in such a way that each forms a layer of the aforementioned wound iron core, and by changing the position of the aforementioned guide in the width direction, any one or more of the stacked directional electromagnetic steel plates are assembled such that, along the entire length of their long side, they are offset in the width direction orthogonal to the aforementioned long side direction relative to the aforementioned directional electromagnetic steel plates forming other layers. So that in the end face of the wound iron core along the thickness direction of the aforementioned directional electromagnetic steel plate and parallel to the long side direction of the aforementioned directional electromagnetic steel plate, When along the aforementioned plate thickness direction The surface roughness of the steel plate portion along the direction connecting the center of the innermost circumference of the directional electromagnetic steel plate of the stacked directional electromagnetic steel plates in the thickness direction with the center of the outermost circumference of the directional electromagnetic steel plate of the wound core in the thickness direction is defined as Ral. When the surface roughness of the directional electromagnetic steel sheet in the direction parallel to the long side direction of the end face of the planar portion of the stacked directional electromagnetic steel sheet is set as Rac, The ratio of Ral to Rac, Ral / Rac, satisfies the relationship 1.5 ≤ Ral / Rac ≤ 12.0.

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