Core and winding device

Abstract

A wound core according to one embodiment of the present invention extends along a first central axis which is the center of rotation. The wound core includes: a pair of outer-circumferential surfaces which are formed with a prescribed radius of curvature; and a pair of corner sections that extend along the first central axis, at circumferential-direction symmetrical positions. In the wound core, a band-shaped material is wound around the outer-circumferential surfaces.

Description

Technical Field

[0001] Embodiments of the present invention relate to a core and a winding device.

Background Art

[0002] There is known a winding device that manufactures a wound body by winding a plurality of foil-shaped strip materials in a stacked state. The winding device includes a core. The winding device rotates the core to wind the material of the wound body around the core to complete the wound body. Such core shapes are roughly classified into circular and non-circular, each having advantages and disadvantages.

[0003] For example, when a circular core rotates, there is almost no need to vary the speed, so the winding speed can be increased. However, after winding is completed, the material on the innermost circumference is likely to loosen, and after pressing the wound body that has completed winding, wrinkles are likely to occur in the material on the innermost circumference side.

[0004] A non-circular core is less likely to have the material on the innermost circumference loosen, but since foil speed fluctuations occur, the acceleration and deceleration speed of the core rotation increases. Therefore, for a non-circular core, rotation control of the core is required so that the winding speed becomes high while suppressing foil speed fluctuations.

[0005] Therefore, there is a need for a core that can suppress loosening of the innermost circumference while reducing the acceleration and deceleration speed.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] The problem to be solved by the present invention is to provide a core and a winding device that can reduce the acceleration and deceleration during rotation while suppressing the loosening of the innermost peripheral material.

Means for Solving the Problem

[0008] The core of the embodiment extends along a first central axis that is the center of rotation. The core has a pair of outer peripheral surfaces formed with a predetermined radius of curvature, and a pair of corner portions extending along the first central axis at symmetric positions in the circumferential direction. A strip-shaped material is wound around the outer peripheral surface of the core. The angle of the tangent of the corner portion is 120° or less. The outer peripheral surface is formed with one radius of curvature. The center of curvature of the outer peripheral surface is located at a position shifted from the second central axis in a direction orthogonal to each of the first central axis and the second central axis connecting the pair of corner portions. The outer peripheral surface is a curved surface formed with one radius of curvature, and the center of curvature of the outer peripheral surface is disposed on the outer periphery of the outer peripheral surface that forms a pair. The corner part is formed in a curved surface shape with a curvature radius of 1 mm or less.

Brief Description of the Drawings

[0009]

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[0010] Hereinafter, the configuration of the winding device 1 and the core 40 according to the embodiment will be described with reference to the respective drawings. In each drawing, for convenience of explanation, the configuration is appropriately enlarged, reduced, or omitted.

[0011] FIG. 1 is an explanatory view schematically showing an example of the configuration of a winding device 1 according to an embodiment, and FIG. 2 is a block diagram showing an example of the control configuration of the winding device 1. FIG. 3 is a cross-sectional view schematically showing the configuration of a core 40 used in the winding device 1. FIG. 4 is an explanatory view schematically showing an example of a wound body 100 manufactured with the core 40. FIG. 5 is an explanatory view schematically showing the configuration of the core 40.

[0012] As shown in FIG. 1, the winding device 1 is a device that manufactures a wound body 100 by winding a plurality of strip-shaped materials (foils) around a core 40 in a stacked state. The wound body 100 manufactured by the winding device 1 is a foil in which at least one of the plurality of strip-shaped materials is formed of a metal material.

[0013] First, a specific example of the wound body 100 manufactured by the winding device 1 will be described. The winding device 1 manufactures the wound body 100 by winding a plurality of strip-shaped materials (strip bodies). As an example, the wound body 100 is used for an electrode group used in a secondary battery such as a lithium ion battery. In the present embodiment, an example in which the winding device 1 manufactures a wound body 100 for an electrode group of a secondary battery using a positive electrode sheet 101, a separator sheet 102, a negative electrode sheet 103, and a separator sheet 104 as four strip-shaped materials will be described.

[0014] FIG. 22 shows an example of the electrode group 155 using the wound body 100 formed by the winding device 1 of the embodiment of FIG. 1. As shown in FIG. 22, in the winding device 1, the electrode group 155 is formed by winding four strip-shaped materials in a state where the four strip-shaped materials are overlapped. The winding device 1 winds the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104 in this order in a state where the four strip-shaped materials, i.e., the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104, are overlapped. In the electrode group 155, the positive electrode 156 is formed by the positive electrode sheet 101, and the negative electrode 157 is formed by the negative electrode sheet 103. Further, in the electrode group 155, separators that electrically insulate between the positive electrode 156 and the negative electrode 157 are formed by the separator sheets 102 and 104.

[0015] Note that the electrode group 155 may be configured such that the inner peripheral side is when the negative electrode sheet 103 is wound and the outer peripheral side is when the positive electrode sheet 101 is wound, or may be configured such that the inner peripheral side is when the positive electrode sheet 101 is wound and the outer peripheral side is when the negative electrode sheet 103 is wound.

[0016] The positive electrode sheet 101 is an electrode sheet that forms the positive electrode of the secondary battery. The positive electrode sheet 101 is an example of a strip-shaped material. The positive electrode sheet 101 is a strip-shaped positive electrode current collector. The positive electrode sheet 101 is formed of, for example, an aluminum foil or an aluminum alloy foil. Further, the positive electrode sheet 101 has a positive electrode active material-containing layer provided on at least one surface. The positive electrode active material-containing layer contains a positive electrode active material.

[0017] The negative electrode sheet 103 is an electrode sheet that forms the negative electrode of the secondary battery. The negative electrode sheet 103 is an example of a strip-shaped material. The negative electrode sheet 103 is a strip-shaped negative electrode current collector. The negative electrode sheet 103 is formed of, for example, a copper foil. Note that the negative electrode sheet 103 may be formed of an aluminum foil or an aluminum alloy foil. Further, the negative electrode sheet 103 has a negative electrode active material-containing layer provided on at least one surface. The negative electrode active material-containing layer contains a negative electrode active material.

[0018] The separator sheets 102 and 104 are disposed between the positive electrode sheet 101 and the negative electrode sheet 103. The separator sheets 102 and 104 constitute an insulating layer. Therefore, in the electrode group 155 manufactured by winding the positive electrode sheet 101 and the negative electrode sheet 103, the separator sheets 102 and 104 serve as a separator 158 that electrically insulates between the positive electrode 156 and the negative electrode 157. Note that, instead of the separator sheets 102 and 104, a solid electrolyte-containing layer may be integrally formed with one of the positive electrode sheet 101 and the negative electrode sheet 103. In this case, in the manufactured electrode group, the solid electrolyte-containing layer electrically insulates between the positive electrode and the negative electrode.

[0019] Next, the winding device 1 will be described. As shown in FIG. 1, the winding device 1 includes, for example, four supply units 5 to 8, four transport units 11 to 14, a core 40, a motor 50, an adjustment mechanism 60, a cutting device 70, and a control device 80.

[0020] In each of the supply units 5 and 6, for example, two reels 10 are arranged, and in each of the supply units 7 and 8, for example, one reel 10 is arranged. The reel 10 holds a roll-shaped raw material around which a strip-shaped material is wound. One corresponding sheet of the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104 is wound around each of the reels 10 in a roll shape. In the supply unit 5, the negative electrode sheet 103 is sent out from one of the two reels 10 to the conveying unit 11, and in the supply unit 6, the positive electrode sheet 101 is sent out from one of the two reels 10 to the conveying unit 12. Also, in the supply unit 7, the separator sheet 102 is sent out from the reel 10 to the conveying unit 13, and in the supply unit 8, the separator sheet 104 is sent out from the reel 10 to the conveying unit 14. Each of the supply units 5 to 8 intermittently sends out one corresponding sheet of the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104 to one corresponding conveying unit among the conveying units 11 to 14. Each of the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104 is sent out by a predetermined length in the longitudinal direction along a pair of long side edges in one feeding.

[0021] A conveying path is formed by each of the conveying units 11 to 14. The conveying unit 11 conveys the negative electrode sheet 103 sent out from the supply unit 5 to the core 40 through the conveying path, and the conveying unit 12 conveys the positive electrode sheet 101 sent out from the supply unit 6 to the core 40 through the conveying path. Also, the conveying unit 13 conveys the separator sheet 102 sent out from the supply unit 7 to the core 40 through the conveying path, and the conveying unit 14 conveys the separator sheet 104 sent out from the supply unit 8 to the core 40 through the conveying path. In each of the conveying units (conveying paths) 11 to 14, the conveying direction in which the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104 are conveyed, that is, the direction toward the core 40, is the downstream side. And in each of the conveying units 11 to 14, the direction opposite to the conveying direction, that is, the direction toward one corresponding supply unit among the supply units 5 to 8, is the upstream side. In an example of FIG. 1, the arrow X1 side is the downstream side of the conveying unit 11, and the arrow X2 side is the upstream side of the conveying unit 11.

[0022] One or more guide rollers 15 are arranged in each of the conveying units (conveying paths) 11 to 14. In an example of FIG. 1, a plurality of guide rollers 15 are arranged in each of the conveying units 11 to 14. In each of the conveying units 11 to 14, that is, in each of the four conveying paths, one of the corresponding positive electrode sheet 101, separator sheet 102, negative electrode sheet 103, and separator sheet 104 is guided to the winding core 40 by the guide roller 15. Note that the number and arrangement of the guide rollers 15 in each of the conveying units 11 to 14 are not limited to the example of FIG. 1 and can be appropriately changed according to the arrangement of the supply units 5 to 8 and the arrangement of the winding core 40 and the like.

[0023] A pinch roller 16 and detection units 17 and 18 are arranged in each of the conveying units 11 and 12. The pinch roller 16 is formed of, for example, rubber. The pinch roller 16 of the conveying unit 11 sandwiches the conveyed negative electrode sheet 103 between itself and a guide roller 15A which is one of the guide rollers 15, and contacts the negative electrode sheet 103 from the side opposite to the guide roller 15A. The pinch roller 16 of the conveying unit 12 sandwiches the conveyed positive electrode sheet 101 between itself and a guide roller 15B which is one of the guide rollers 15, and contacts the positive electrode sheet 101 from the side opposite to the guide roller 15B. In each of the conveying units (conveying paths) 11 and 12, the pinch roller 16 conveys the strip (one of the corresponding ones of 51 and 52) to the winding core 40 at a stable conveying speed. Among the pinch rollers 16, the one arranged in the conveying unit 11 is referred to as a pinch roller 16A, and the one arranged in the conveying unit 12 is referred to as a pinch roller 16B.

[0024] Also, in each of the conveying units 11 and 12, a detection unit (first detection unit) 17 is disposed upstream of the pinch roller 16 and between the pinch roller 16 and one of the corresponding supply units (5, 6). And in each of the conveying units 11 and 12, a detection unit (second detection unit) 18 is disposed downstream of the pinch roller 16 and between the pinch roller 16 and the core 40. In each of the conveying units (conveying paths) 11 and 12, the detection unit 17 detects an abnormally shaped portion formed in one of the belt-like bodies (51, 52) at a position upstream of the pinch roller 16. And in each of the conveying units (conveying paths) 11 and 12, the detection unit 18 detects an abnormally shaped portion formed in one of the belt-like bodies (51, 52) at a position downstream of the pinch roller 16. In each of the detection units 17 and 18, for example, a CCD camera or a laser displacement meter is used to detect the abnormally shaped portion. Also, examples of the abnormally shaped portions formed in each of the negative electrode sheet 103 and the positive electrode sheet 101 include uneven portions, wrinkles, and creases. Note that among the detection units 17 and 18, those for performing detection in the conveying unit 11 are the detection units 17A and 18A, and those for performing detection in the conveying unit 12 are the detection units 17B and 18B.

[0025] The core 40 is attached to a frame (not shown) or the like. As shown in FIG. 2, the core 40 is connected to a motor 50. The core 40 rotates when the motor 50 is driven. The core 40 has a first central axis C1 that is the center of rotation. The core 40 rotates about the first central axis C1 with respect to a frame or the like by the drive of the motor 50.

[0026] The core 40 holds the stacked positive electrode sheet 101, separator sheet 102, negative electrode sheet 103, and separator sheet 104, and winds the positive electrode sheet 101, separator sheet 102, negative electrode sheet 103, and separator sheet 104 around the outer peripheral surface by rotating about the first central axis C1.

[0027] The core 40 is formed in a columnar shape extending along the first central axis C1. The core 40 is formed such that at least the shape along the first central axis C1 of the part where the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104 are wound is the same or substantially the same. As shown in FIG. 3, the core 40 has two corner portions 41 formed at two symmetric positions in the circumferential direction, and two outer peripheral surfaces 42 formed between the apex portions of the two corner portions 41. In other words, the core 40 is formed in a point-symmetric shape centered on the first central axis C1, or in a symmetric shape centered on the second central axis C2 connecting the two corner portions 41. Further, it is preferable that the core 40 does not have a straight portion extending in a direction intersecting the first central axis C1 at the outer peripheral portion where the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104 are wound. In other words, it is preferable that the core 40 does not have a straight portion on the outer surface along the circumferential direction.

[0028] For example, as shown in FIG. 4, the corner portion 41 forms a folding line 100a on at least the positive electrode sheet 101 or the negative electrode sheet 103 that becomes the innermost circumference among the wound bodies 100 obtained by winding the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104.

[0029] The angle θ of the tangent line of the corner portion 41 shown in FIG. 3 is set to an angle at which the fluctuation of the angular velocity is not large and the folding line 100a can be formed. As a specific example, the angle θ of the tangent line of the corner portion 41 is formed to be 120° or less. The corner portion 41 is preferably set to 90°. By setting the angle θ of the tangent line of the corner portion 41 to 120° or less, the actual angle of the corner portion 41 becomes an acute angle at which the folding line 100a can be formed on the material. Therefore, as shown in FIG. 4, the innermost circumferential portion of the wound body 100 wound by the core 40 having such a corner portion 41 has the folding line 100a formed, and the portion of the wound body 100 where the folding line 100a is formed is substantially in an acute angle shape.

[0030] The vertex of the corner portion 41 is formed such that it does not damage the contacting positive electrode sheet 101 or negative electrode sheet 103 and can form the folding line 100a. For example, the vertex of the corner portion 41 is formed in a curved surface shape with a curvature radius r of 1 mm or less. As an example, the vertex of the corner portion 41 is formed in a curved surface shape with a curvature radius r of 0.5 mm.

[0031] The outer peripheral surface 42 extends along the first central axis C1. The outer peripheral surface 42 is formed with, for example, a single curvature radius. Also, the pair of outer peripheral surfaces 42 are formed with a curvature radius such that the angle θ of the tangent line of the corner portion 41 is 120° or less. The two ridge portions formed by the pair of outer peripheral surfaces 42 constitute the pair of corner portions 41.

[0032] As shown schematically in the cross-sectional shape of the winding core 40 in FIG. 3, the curvature centers C0 of the two outer peripheral surfaces 42 are in a direction orthogonal or substantially orthogonal to the first central axis C1 and in a direction orthogonal to the second central axis C2 connecting the two corner portions 41, and are at positions shifted from the second central axis C2. That is, as shown in FIG. 5, in the cross-sectional shape of the winding core 40 in a cross-section orthogonal or substantially orthogonal to the first central axis C1, when the centers C0 of the two virtual circles CI with a predetermined radius are arranged at shifted positions, as a more specific example, when the centers C0 of the two virtual circles CI with a predetermined radius are arranged at positions shifted from the second central axis C2 in a direction orthogonal to each of the first central axis C1 and the second central axis C2 connecting the two corner portions 41, it is formed in the same shape or substantially the same shape as the shape where the two virtual circles CI intersect.

[0033] In the example of the winding core 40 shown in FIG. 5, the center C0 of one virtual circle CI is arranged on the outer periphery of the other virtual circle CI. That is, in the configuration of the winding core 40 shown in FIG. 5, the distance between the centers C0 of the two virtual circles CI is the same as the radius of the virtual circle CI.

[0034] Next, a specific example of the core 40 will be described. The core 40 has, for example, a pair (two) of chip pieces 45. The core 40 holds the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and / or the separator sheet 104 disposed in the slit 45a between the opposing surfaces of the pair of chip pieces 45. For example, the core 40 has a clamp 46 that holds the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104 disposed in the slit 45a.

[0035] The pair of chip pieces 45 forms a slit 45a therebetween by having a space between their opposing surfaces. The pair of chip pieces 45 each have one corner portion 41. The pair of chip pieces 45 are held in a predetermined arrangement relationship to constitute a pair of corner portions 41 and a pair of outer peripheral surfaces 42. Further, the core 40 may have a moving mechanism and a drive source for varying the distance between the pair of chip pieces 45. For example, the core 40 may be configured to move the pair of chip pieces 45 such that the width of the slit 45a decreases when removing the wound winding body 100 from the core 40.

[0036] The opposing surfaces of the pair of chip pieces 45 are, for example, inclined (intersecting) inclined surfaces with respect to the second central axis C2. Thus, the slit 45a is inclined with respect to the second central axis C2.

[0037] The slit 45a is a gap or opening formed between the opposing surfaces of the pair of chip pieces 45. The slit 45a extends along the first central axis C1. The slit 45a is formed in a shape into which the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and / or the separator sheet 104 can be inserted. Note that the width of the slit 45a in the circumferential direction of the core 40 is preferably such that the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and / or the separator sheet 104 can be inserted and is as small as possible.

[0038] Since the slit 45a of such a core 40 is inclined with respect to the second central axis C2, the cross-sectional shape of the core 40 including the slit 45a is a point-symmetric shape centered on the first central axis C1. Further, a part of the outer peripheral surface 42 of the core 40 is intermittently formed by the slit 45a.

[0039] Also, by making the slit 45a inclined with respect to the second central axis C2, the outer surface portions forming the pair of outer peripheral surfaces 42 of the chip 45 have a configuration including a first outer peripheral portion 45b and a second outer peripheral portion 45c having a longer circumferential length than the first outer peripheral portion 45b. Then, the first outer peripheral portion 45b of one chip 45 and the second outer peripheral portion 45c of the other chip 45 constitute one outer peripheral surface 42 having the slit 45a. Also, the second outer peripheral portion 45c of one chip 45 and the first outer peripheral portion 45b of the other chip 45 constitute the other outer peripheral surface 42 having the slit 45a.

[0040] The clamp 46 is, for example, a chuck that holds the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and / or the separator sheet 104 disposed in the slit 45a. The clamp 46 opens and closes by power from a motor or the like, as indicated by the arrow in FIG. 3, for example. In FIG. 3, the clamp 46 in the open state is shown by a solid line, and the clamp 46 in the closed state is shown by a broken line.

[0041] The motor 50 is, for example, a servo motor. The rotation speed of the motor 50 is controlled by the control device 80.

[0042] The adjustment mechanism 60 includes a roller 61 and a drive device 65. The roller 61 adjusts the insertion angle of the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104 supplied to the core 40 to the roller 61. That is, the roller 61 defines the insertion angle of the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104 with respect to the core 40. The drive device 65 moves the roller 61 by driving it. Specifically, the drive device 65 moves the roller 61 between a reference position and a winding position.

[0043] As an example, the driving device 65 includes a slider and a servo motor, and the driving of the slider and the servo motor moves the roller 61 along a predetermined direction. In another example, the driving device 65 includes an arm and an air cylinder. One end of the arm is rotatably attached to a frame or the like, and the roller 61 is fixed to the other end of the arm. An air cylinder is connected to the arm. The air cylinder rotates the arm by expanding and contracting along a predetermined direction. Then, as the arm rotates, the roller 61 moves along an arc centered on the rotation axis of the arm.

[0044] The reference position is the position where the roller 61 is disposed when the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104 are attached to the winding core 40. When attaching the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104 to the winding core 40, for example, with the end of the positive electrode sheet 101 held by the winding core 40, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104 are inserted between the outer peripheral surface of the winding core 40 and the positive electrode sheet 101.

[0045] The winding position is the position where the roller 61 is disposed when the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104 are wound around the winding core 40. When attaching the positive electrode sheet 101 and the negative electrode sheet 103 to the winding core 40, for example, the roller 61 moves to the winding position and defines the insertion angle with respect to the insertion position of the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104 with respect to the winding core 40.

[0046] The cutting device 70 cuts the positive electrode sheet 101, separator sheet 102, negative electrode sheet 103, and separator sheet 104 supplied to the core 40. For example, the cutting device 70 includes a cutter 71 that performs cutting and a drive source 72 such as a motor that moves the cutter 71. The cutting device 70 moves the cutter 71 between a standby position and a cutting position by the drive source 72, and cuts the positive electrode sheet 101, separator sheet 102, negative electrode sheet 103, and separator sheet 104 at the cutting position.

[0047] The control device 80 is a processing device such as a computer, for example. The control device 80 includes a processor or integrated circuit (control circuit) including a CPU (Central Processing Unit), ASIC (Application Specific Integrated Circuit), or FPGA (Field Programmable Gate Array), etc., and a storage medium such as a memory. The control device 80 may include only one integrated circuit or the like, or may include a plurality of integrated circuits or the like. The control device 80 performs processing by executing a program or the like stored in a storage medium or the like. The control device 80 controls the operations of each element provided in the winding device 1. The control device 80 controls the driving of, for example, the four supply units 5 to 8, the four conveying units 11 to 14, the clamp 46, the motor 50, the driving device 65 of the adjustment mechanism 60, the cutting device 70, etc. Further, the control device 80 may further include an input unit for an operator or the like to input process conditions, operation conditions, etc., and a display unit for displaying an operation state, an abnormality display, etc.

[0048] The control device 80 performs rotational control to reduce the difference in angular velocity in one rotation (half rotation) of the core 40 by varying the rotational speed of the motor 50 according to the distance from the rotation center of the core 40 to the outer surface where the positive electrode sheet 101, separator sheet 102, negative electrode sheet 103, and separator sheet 104 contact.

[0049] Next, an example of a method for manufacturing an electrode group using the winding device 1 of the present embodiment will be described with reference to FIG. 6.

[0050] First, the control device 80 performs an attachment process. As a specific example, the control device 80 controls the four supply units 5 to 8 and the four transport units 11 to 14, and inserts the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and / or the separator sheet 104 into the slit 45a between the pair of chip pieces 45 (step ST1). Next, the control device 80 controls the clamp 46 to hold the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and / or the separator sheet 104 inserted into the slit 45a (step ST2). When the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and / or the separator sheet 104 are held by the core 40, the control device 80 controls the cutting device 70 to cut the portion on the leading end side of the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and / or the separator sheet 104 inserted into the slit 45a (step ST3). Through these steps, the attachment process is completed.

[0051] Note that, for example, the strip-shaped material inserted into the slit 45a and held by the clamp 46 may be any one of the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104, or may be all of the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104. For example, when holding any one of the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104 in the slit 45a, the control device 80 may have a step of inserting another strip-shaped material between the core 40 and the held strip-shaped material.

[0052] Next, as a moving step, the control device 80 moves the roller 61 from the reference position to the winding position by controlling the drive of the drive device 65. Next, as a winding step, the control device 80 drives and controls the motor 50 to rotate the winding core 40, and winds the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104 a predetermined number of times (step ST4). For example, in the winding step, the winding core 40 is rotated in a direction reaching the corner portion 41 through the first outer peripheral portion 45b where the length of the material in the circumferential direction of the chip 45 is short after the start of winding. In the winding step, the control device 80 controls the motor 50 to rotate the winding core 40 so as to reduce the difference in angular velocity generated at the winding axis angle in one rotation (half rotation) of the winding core 40.

[0053] Thereby, a wound body 100 in which the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104 are wound a predetermined number of times is formed. When the wound body 100 is formed, the control device 80 ends the winding step.

[0054] Next, the control device 80 controls the clamp 46 to release the holding of the manufactured wound body 100, controls the cutting device 70 to cut the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104, and removes the wound body 100 from the winding core 40. As the attachment step of step ST1, the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104 to be manufactured next are attached to the winding core. In the attachment step of the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104 of the wound body 100 to be manufactured next, the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104 may be cut as described in step ST3, and the manufactured wound body 100 may be separated from the positive electrode sheet 101 and the negative electrode sheet 103.

[0055] For example, as shown in FIG. 4, the wound body 100 manufactured by the winding device 1 is pressed from a direction orthogonal or substantially orthogonal to the second central axis C2 by a press or the like (step ST5). For example, the press performed by the press is a flat press. Further, as an example of the pressing conditions, a load of 1 t is applied to the wound body 100 for about several tens of seconds under a temperature condition of 100° C. to press the wound body 100. Thereby, the wound body 100 is formed into a flat shape. By way of example of these steps, a wound body 100 such as an electrode group is manufactured.

[0056] Next, the effects of the winding device 1 and the winding core 40 of the present embodiment will be described. The winding core 40 has a pair of corner portions 41 formed at a predetermined angle with respect to the tangent line, and a pair of outer peripheral surfaces 42 having a predetermined radius of curvature between the pair of corner portions 41. The winding core 40 can form a folding line 100a on at least the innermost peripheral material by the pair of corner portions 41. For example, the winding core 40 can form a folding line 100a on at least one of the positive electrode sheet 101 and the negative electrode sheet 103 by the pair of corner portions 41. The folding line 100a is formed by the plastic deformation of the innermost peripheral material during pressing. The folding line 100a serves as a fold during the pressing of the wound body 100 and guides the deformation of the positive electrode sheet 101 and the negative electrode sheet 103 (materials) during the press forming of the wound body 100.

[0057] Further, the folding line 100a can increase the friction coefficient of the overlapping portion of the innermost layer (material) where the folding line 100a is formed and the layer (material) adjacent to this innermost layer. For example, the folding line 100a can increase the friction coefficient of the overlapping portion of the adjacent positive electrode sheet 101 and negative electrode sheet 103 via the separator sheets 102, 104. Thereby, the end portion of the strip-shaped material (positive electrode sheet 101 or negative electrode sheet 103) on the innermost peripheral side of the wound body 100 is fixed by the folding line 100a. Since the wound body 100 manufactured with the winding core 40 has the material (positive electrode sheet 101 or negative electrode sheet 103) on the innermost peripheral side fixed, it is possible to prevent the material (positive electrode sheet 101 or negative electrode sheet 103) on the innermost peripheral side from shifting. That is, the winding core 40 can crease the innermost peripheral foil of the wound body 100 at the corner portion 41 which is the edge portion when the material is wound, and make the innermost peripheral foil in a state where it is difficult to shift.

[0058] Therefore, the shape of the manufactured wound body 100 is maintained as the shape after removing the winding core 40 from the wound body 100. Thereby, it is possible to suppress looseness from occurring in the positive electrode sheet 101 or negative electrode sheet 103 on the innermost peripheral side of the wound body 100. Further, since the shape of the wound body 100 is maintained, during pressing, the positive electrode sheet 101 or negative electrode sheet 103 on the innermost peripheral side can be pressed without shifting, so that it is possible to suppress the occurrence of wrinkles and steps in the plastically deformed positive electrode sheet 101 or negative electrode sheet 103 on the innermost peripheral side during pressing.

[0059] Further, the winding device 1 can form the folding line 100a on the end portion side of the material by rotating the winding core 40 in the direction from the material passing through the first outer peripheral portion 45b having a short circumferential length of the chip 45 to the corner portion 41 after the start of winding. Thereby, the winding device 1 and the winding core 40 can more effectively prevent the occurrence of looseness at the end portion on the innermost peripheral side of the material. Therefore, the winding device 1 and the winding core 40 can manufacture a wound body 100 of excellent quality.

[0060] Further, the core 40 has a pair of outer peripheral surfaces 42 between a pair of corner portions 41 formed as a curved surface with a single radius of curvature, so that it has no straight portion, and the change in the distance from the rotation center of the core 40 to the outer surface in the circumferential direction can be minimized.

[0061] That is, when using a core whose circumferential shape (cross-sectional shape) of the outer peripheral surface is other than circular, the distance between the point where the belt-like material of the core is applied and the rotation center of the core varies during one rotation (half rotation). That is, depending on the angle of the winding axis, the distance between the point where the belt-like material of the core is applied and the rotation center of the core changes. Therefore, when winding the material, the angular velocity varies depending on the radius of the core. If there is a variation in the traveling speed of the material (object to be wound), the traveling of the object to be wound will shift or bounce, making it difficult to wind the object to be wound neatly. To solve this, when the angular velocity increases, the rotation speed of the core is decreased, and when the angular velocity decreases, the rotation of the core is increased, and the rotation of the core is adjusted by a control device 80 or the like to suppress the variation in the winding speed. However, in the control of the rotation speed of the core, when the angular velocity fluctuates rapidly, rapid acceleration and deceleration of the core are required. When the core is rapidly accelerated and decelerated, it becomes difficult for the motor 50 to follow, making it difficult to wind the material at high speed and reducing the productivity of the wound body.

[0062] However, since the core 40 of the embodiment can minimize the change in the distance from the rotation center of the core 40 to the outer surface in the circumferential direction, the acceleration and deceleration per rotation (half rotation) of the core 40 can be reduced. That is, by using the core 40, the speed change of the winding axis becomes small. Therefore, the core 40 does not need to be rapidly accelerated or decelerated, and it is possible to wind the material at high speed. Therefore, the core 40 and the winding device 1 can suppress a decrease in productivity.

[0063] Next, the core 40 of such an embodiment will be described in comparison with a conventionally used core of a comparative example. First, the cores 40A to 40D of Comparative Example 1 will be described with reference to FIGS. 7 to 10.

[0064] [Comparative Example 1] As shown in Fig. 7, the core 40A of Comparative Example 1 is formed with a circular cross-sectional shape (circumferential shape) perpendicular to the first central axis C1.

[0065] [Comparative Example 2] As shown in Fig. 8, the core 40B of Comparative Example 2 is formed with a flat hexagonal cross-sectional shape (circumferential shape) perpendicular to the first central axis C1.

[0066] [Comparative Example 3] As shown in Fig. 9, the core 40C of Comparative Example 3 is formed with a rhombic cross-sectional shape (circumferential shape) perpendicular to the first central axis C1.

[0067] [Comparative Example 4] As shown in Fig. 10, the core 40D of Comparative Example 4 is formed with an elliptical cross-sectional shape (circumferential shape) perpendicular to the first central axis C1.

[0068] Next, the cores 40A to 40D of these comparative examples will be compared and described with the core 40 of the embodiment.

[0069] [Comparison between Embodiment and Comparative Examples] First, the core 40A of Comparative Example 1 and the core 40 of the embodiment will be compared. Fig. 11 shows an example of the wound body 100A manufactured with the core 40A of Comparative Example 1. Since there is almost no need to vary the speed when the core 40A rotates, the winding speed can be increased to a high speed, and the productivity is high. However, as in the wound body 100A obtained by winding the material with the core 40A shown in Fig. 11, the end of the innermost material is not fixed, and looseness is likely to occur in the innermost material. Looseness occurs when removing the core 40A from the wound body 100A, when moving the wound body 100A after removal, and when pressing the wound body 100A. It is impossible to correct the wound body 100A after the material has loosened.

[0070] In addition, the wound body 100A in which looseness has occurred in the material becomes a defective product depending on the characteristics. Also, when pressing the material in a loose state, there is no place for the material in the loose part, and wrinkles such as folding into a Z shape occur. For this reason, the wrinkled part generated when pressed becomes a step, and the step part breaks through other parts as foreign matter, so that the characteristics of the wound body 100A (electrode group) become defective.

[0071] In this way, the wound body 100A in which looseness has occurred in the material is likely to become a defective product. Also, since the amount of deformation of the wound body 100A during pressing is large, even if there is no looseness, the shape of the material on the innermost peripheral side of the wound body 100A may collapse during pressing. Also, during pressing, there is a lot of rubbing between adjacent materials of the wound body 100A, so there is a risk of causing damage.

[0072] On the other hand, according to the winding core 40 of the present embodiment, as shown in FIG. 4, a folding line 100a can be formed on at least the innermost peripheral material of the wound body 100 by the apex portions of the pair of corner portions 41. Therefore, the winding core 40 of the embodiment can suppress the occurrence of looseness on the innermost peripheral side of the wound body 100. Also, by making the outer peripheral surface 42 of the winding core 40 into a curved surface with a predetermined radius of curvature, it is possible to suppress the variation of the speed when the winding core 40 rotates, so that the rotational speed can be increased. Therefore, the winding core 40 of the embodiment can ensure high productivity.

[0073] Next, the core 40B of Comparative Example 2 and the core 40C of Comparative Example 3 are compared with the core 40 of the embodiment. After winding, the cores 40B of Comparative Example 2 and 40C of Comparative Example 3 can form a folding line, which is a trace of plastic deformation, on the innermost peripheral material. Therefore, the wound body is difficult to loosen, and the cores 40B of Comparative Example 2 and 40C of Comparative Example 3 can wind the wound body in a shape close to the shape after pressing. Thus, similar to the core 40 of the embodiment, the amount of deformation and the amount of rubbing during pressing can be reduced. The cores 40B of Comparative Example 2 and 40C of Comparative Example 3 can reduce the damage to the wound body, so the manufactured wound body is excellent in terms of quality. However, in the cross-sectional shape (circumferential direction shape), since a straight portion is formed on the outer peripheral surface, the cores 40B of Comparative Example 2 and 40C of Comparative Example 3 have a large fluctuation in the angular velocity during winding, and it is difficult to wind the material at high speed.

[0074] Using the specific examples of FIGS. 12 to 17, the core 40 of the embodiment and the core 40B of Comparative Example 2 will be described. FIGS. 12 and 13 are diagrams respectively showing the states at each winding axis angle (rotation angle of the core) when the core 40 of the embodiment and the core 40B of Comparative Example 2 are rotated by half a turn. In FIGS. 12 and 13, the rotation directions R of the cores 40 and 40B are indicated by arrows.

[0075] FIGS. 14 and 15 are explanatory diagrams showing the relationship between the winding axis angle and the material speed (angular velocity) when the core is rotated at a constant speed for the core 40 of the embodiment and the core 40B of Comparative Example 2 respectively. FIGS. 16 and 17 are explanatory diagrams showing the relationship between the winding axis angle and the winding axis speed (rotation speed) when the core is rotationally controlled so that the material speed becomes constant for the core 40 of the embodiment and the core 40B of Comparative Example 2 respectively. Since the core 40C of Comparative Example 3 has the same characteristics as the core 40B of Comparative Example 2, detailed description thereof will be omitted.

[0076] As shown in FIGS. 13 and 15, when the core 40B of Comparative Example 2 is rotated, when the material is wound around a part of the outer peripheral surface (straight part) that linearly extends in the circumferential direction, the fluctuation of the angular velocity becomes large. For this reason, as shown in FIG. 17, when the core 40B is controlled to rotate so that the angular velocity becomes constant, the range of acceleration and deceleration of the winding shaft speed becomes large. In the core 40B of Comparative Example 2, rapid acceleration and rapid deceleration of the motor 50 are required. However, due to the performance of the motor 50, rapid acceleration and rapid deceleration are difficult, and thus the control of the motor 50 becomes difficult. Therefore, it is difficult to wind the material at high speed with the core 40B of Comparative Example 2.

[0077] On the other hand, as shown in FIGS. 12 and 14, when the core 40 of the present embodiment is rotated, the fluctuation of the angular velocity becomes smaller due to the outer peripheral surface 42 having a predetermined radius of curvature in the circumferential direction as compared with Comparative Example 2. For this reason, as shown in FIG. 16, when the core 40 is controlled to rotate so that the angular velocity becomes constant, the range of acceleration and deceleration of the winding shaft speed becomes smaller as compared with Comparative Example 2. In the core 40 of the embodiment, since it is not necessary to rapidly accelerate and rapidly decelerate the motor 50, the speed adjustment of the winding shaft can be performed gently. Therefore, the core 40 of the embodiment is easier to control than the core 40B of Comparative Example 2, and the material can be wound at a higher speed than the core 40B of Comparative Example 2. In addition, similar to the core 40B of Comparative Example 2, the core 40 of the embodiment can form the folding line 100a on the innermost peripheral material by the pair of corner portions 41.

[0078] Next, the core 40D of Comparative Example 4 is compared with the core 40 of the embodiment. Since the core 40D of Comparative Example 4 can reduce the fluctuation of the angular velocity in the same manner as the core 40 of the present embodiment, the speed adjustment of the winding shaft can be performed gently. Therefore, the core 40D of Comparative Example 4 has good followability of the motor, similar to the core 40 of the present embodiment. However, different from the core 40 of the present embodiment, the core 40D of Comparative Example 4 cannot form a folding line on the innermost peripheral material of the wound body. Therefore, since the innermost peripheral end of the wound body manufactured by the core 40D of Comparative Example 4 is not fixed, looseness of the material is likely to occur as in Comparative Example 1.

[0079] [Evaluation Tests of Embodiments and Comparative Examples] Next, evaluation tests of the core 40 of the embodiment and the core 40A of Comparative Example 1 will be described below. As the evaluation test, the wound body wound by the core 40 of the embodiment and the core 40A of Comparative Example 1 was pressed, the material on the innermost circumference of the pressed wound body was visually confirmed, and the presence or absence of wrinkles was judged.

[0080] The evaluation test results are shown in FIG. 18. FIG. 19 shows an example of the material on the innermost circumference of the wound body 100 after pressing manufactured by the core 40 of the embodiment, and FIG. 20 shows an example of the material on the innermost circumference of the wound body 100A after pressing manufactured by the core 40A of Comparative Example 1.

[0081] As shown in FIG. 18, with the core 40 of the embodiment, 247 wound bodies 100 were produced, and in all cases, as shown in FIG. 19, no wrinkles occurred at the bending position of the innermost circumference of the wound body 100 after pressing. This is presumably because the folding line 100a was formed in the material on the innermost circumference of the wound body 100 before pressing, so that no bending or displacement occurred in the material on the innermost circumference.

[0082] On the other hand, as shown in FIG. 18, with the core 40A of Comparative Example 1, when 29 wound bodies 100A were produced, wrinkles as indicated by the arrow in FIG. 20 occurred at the bending position of the material on the innermost circumference of the wound body 100A after pressing. Wrinkles occurred in 24% of the wound bodies manufactured by the core 40A of Comparative Example 1. This is presumably because the folding line 100a could not be formed in the core 40A of Comparative Example 1, and no folding line was formed in the wound body 100A.

[0083] From the results of such evaluation tests, it is clear that the core 40 of the embodiment can suppress the occurrence of wrinkles in the material by forming the folding line 100a in the wound body 100. Therefore, the core 40 of the embodiment can maintain high productivity of the wound body 100 and improve the quality.

[0084] Next, an example of the non-aqueous electrolyte battery 2 using the wound body 100 described above as the electrode group 155 will be described with reference to FIG. 21. FIG. 21 is an exploded perspective view of an example of the non-aqueous electrolyte battery of the embodiment.

[0085] The secondary battery shown in FIG. 21 is a sealed rectangular non-aqueous electrolyte battery 2. The non-aqueous electrolyte battery 2 shown in FIG. 21 includes an exterior can 151, a lid 152, a positive electrode external terminal 153, a negative electrode external terminal 154, and an electrode group 155. The exterior can 151 and the lid 152 constitute an exterior member. The exterior can 151 has a bottomed rectangular cylindrical shape. The exterior can 151 is formed of a metal such as aluminum, an aluminum alloy, iron, or stainless steel, for example.

[0086] The flat electrode group 155 is formed by winding a positive electrode 156 and a negative electrode 157 around a winding core 40 with a separator 158 therebetween, and then pressing it flat. The positive electrode 156 is formed by a positive electrode sheet 101. The positive electrode 156 includes, for example, a strip-shaped positive electrode current collector 156a made of a metal foil, a positive electrode current collector tab 156b formed of one end portion parallel to the long side of the positive electrode current collector, and a positive electrode material layer (positive electrode active material-containing layer) 156c formed on the positive electrode current collector except at least the portion of the positive electrode current collector tab 156b.

[0087] The negative electrode 157 is formed by a negative electrode sheet 103. The negative electrode 157 includes, for example, a strip-shaped negative electrode current collector 157a made of a metal foil, a negative electrode current collector tab 157b formed of one end portion parallel to the long side of the negative electrode current collector, and a negative electrode material layer (negative electrode active material-containing layer) 157c formed on the negative electrode current collector except at least the portion of the negative electrode current collector tab 157b. In FIG. 22, dots are described in the regions indicating the active material-containing layers 156c and 157c for the purpose of explaining the configuration. The separator 158 is formed by separator sheets 102 and 104.

[0088] Such a positive electrode 156, separator 158, and negative electrode 157 are wound with the positions of the positive electrode 156 and the negative electrode 157 shifted so that the positive electrode current collector tab 156b protrudes from the separator 158 in the winding axis direction of the electrode group, and the negative electrode current collector tab 157b protrudes from the separator 158 in the opposite direction. By such winding, as shown in FIG. 3, the electrode group 155 has the positive electrode current collector tab 156b wound in a spiral shape protruding from one end face, and the negative electrode current collector tab 157b wound in a spiral shape protruding from the other end face. A non-aqueous electrolyte (not shown) is impregnated into the electrode group 155.

[0089] As shown in FIG. 21, the positive electrode current collector tab 156b and the negative electrode current collector tab 157b are each divided into two bundles with the vicinity of the winding center of the electrode group as a boundary. The conductive clamping member 159 has a substantially U-shaped first and second clamping portions 159a, 159b and a connecting portion 159c that electrically connects the first clamping portion 159a and the second clamping portion 159b. One bundle of the positive and negative electrode current collector tabs 156b, 157b is clamped by the first clamping portion 159a, and the other bundle is clamped by the second clamping portion 159b.

[0090] The positive electrode lead 160 has a substantially rectangular support plate 160a, a through hole 160b opened in the support plate 160a, and strip-shaped current collecting portions 160c, 160d that branch in two directions from the support plate 160a and extend downward. On the other hand, the negative electrode lead 161 has a substantially rectangular support plate 161a, a through hole 161b opened in the support plate 161a, and strip-shaped current collecting portions 161c, 161d that branch in two directions from the support plate 161a and extend downward.

[0091] The positive electrode lead 160 sandwiches the clamping member 159 between the current collecting portions 160c, 160d. The current collecting portion 160c is disposed in the first clamping portion 159a of the clamping member 159. The current collecting portion 160d is disposed in the second clamping portion 159b. The current collecting portions 160c, 160d, the first and second clamping portions 159a, 159b, and the positive electrode current collector tab 156b are joined by, for example, ultrasonic welding. Thereby, the positive electrode 156 of the electrode group 155 and the positive electrode lead 160 are electrically connected via the positive electrode current collector tab 156b.

[0092] The negative electrode lead 161 sandwiches the sandwiching member 159 between the current collecting portions 161c and 161d. The current collecting portion 161c is disposed on the first sandwiching portion 159a of the sandwiching member 159. On the other hand, the current collecting portion 161d is disposed on the second sandwiching portion 159b. The current collecting portions 161c and 161d, the first and second sandwiching portions 159a and 159b, and the negative electrode current collecting tab 157b are joined by, for example, ultrasonic welding. Thereby, the negative electrode 157 of the electrode group 155 and the negative electrode lead 161 are electrically connected via the negative electrode current collecting tab 157b.

[0093] The materials of the positive and negative electrode leads 160 and 161 and the sandwiching member 159 are not particularly specified, but it is desirable that they be the same as the materials of the positive and negative electrode external terminals 153 and 154. For example, aluminum or an aluminum alloy is used for the positive electrode external terminal 153, and for example, aluminum, an aluminum alloy, copper, nickel, iron plated with nickel, etc. are used for the negative electrode external terminal 154. For example, when the material of the external terminal is aluminum or an aluminum alloy, it is preferable that the material of the lead be aluminum or an aluminum alloy. Also, when the external terminal is copper, it is desirable that the material of the lead be copper or the like.

[0094] The rectangular plate-shaped lid 152 is seam welded to the opening of the exterior can 151 by, for example, a laser. The lid 152 is formed of a metal such as, for example, aluminum, an aluminum alloy, iron, or stainless steel. It is desirable that the lid 152 and the exterior can 151 be formed of the same type of metal. The positive electrode external terminal 153 is electrically connected to the support plate 160a of the positive electrode lead 160, and the negative electrode external terminal 154 is electrically connected to the support plate 161a of the negative electrode lead 161. The insulating gasket 162 is disposed between the positive and negative electrode external terminals 153 and 154 and the lid 152, and electrically insulates the positive and negative electrode external terminals 153 and 154 from the lid 152. The insulating gasket 162 is preferably a resin molded product.

[0095] Next, an example of the manufacturing method of this non-aqueous electrolyte battery 2 is shown in FIG. 22. First, slurry preparation, coating, slitting, roll pressing, etc. are performed, and a positive electrode 156 (positive electrode sheet 101) and a negative electrode 157 (negative electrode sheet 103) having a porous layer formed on the surface by an electrospinning method as needed are transported to the bobbin 40 of the winding device 1 (steps 201, 202). Next, with at least a separator 158 (separator sheets 102, 104), which is an insulating layer, interposed between the positive electrode sheet 101 and the negative electrode sheet 103, the positive electrode sheet 101 and the negative electrode sheet 103 are wound around the bobbin 40 to produce a wound body 100 (steps ST1 to ST4, step 203), and the wound body 100 is flat-pressed by a press or the like (step ST5, step 204). Through these steps, an electrode group 155 is manufactured. Next, the electrode group 155 is housed in an exterior container, and after drying the electrode group 155 (step 205), an electrolytic solution is poured into the exterior container (step 206). Next, after sealing the exterior container, after performing an aging treatment or the like, a degassing process is carried out (step 207). Thereafter, charge and discharge are performed on the non-aqueous electrolyte battery 2 (step 208), a pre-shipment inspection of the non-aqueous electrolyte battery 2 is carried out (step 209), and the non-aqueous electrolyte battery 2 is shipped (step 210). In this way, by manufacturing the electrode group 155 with the above-described bobbin 40, a high-quality non-aqueous electrolyte battery 2 can be provided with high productivity.

[0096] According to the bobbin 40 and the winding device 1 of the above-described embodiment, by having a pair of corner portions 41 and a pair of outer peripheral surfaces 42, it is possible to suppress the loosening of the innermost circumferential belt-like material (positive electrode sheet 101 or negative electrode sheet 103) and reduce the acceleration and deceleration speed per one rotation (half rotation) during rotation.

[0097] Note that the above-described embodiments are illustrative, and their configurations are not limited. For example, in the above example, although an example in which the pair of outer peripheral surfaces 42 of the core 40 are formed with a single radius of curvature has been described, it is not limited thereto. For example, like the core 40 of another embodiment shown in FIG. 23, each of the pair of outer peripheral surfaces 42 may be a curved surface formed with a plurality of different radii of curvature. For example, in the example schematically shown in FIG. 23, the core 40 has an outer peripheral surface 42 formed in an elliptical shape, and a pair of corner portions 41 are formed at both longitudinal ends. Even with such a core 40, it is possible to reduce the acceleration and deceleration per rotation (half rotation) during rotation while suppressing the loosening of the innermost materials 101 and 103.

[0098] Also, as described above, if the winding device 1 and the core 40 are a winding body 100 that uses a material capable of forming the folding line 100a and is pressed to be flat, winding bodies 100 for various applications can be manufactured.

[0099] That is, in the above-described embodiments, as an example, a configuration in which the winding body 100 used for the electrode group 155 of the secondary battery 2 is manufactured using the core 40 and the winding device 1 has been described, but it is not limited thereto. That is, if the winding device 1 is configured to manufacture a winding body in a state where a plurality of belt-like bodies are overlapped, it can be used for manufacturing winding bodies other than the electrode group 155 of the secondary battery 2. For example, the winding body 100 manufactured by the winding device 1 may be used for a capacitor or a lithium-ion capacitor. Further, the winding body 100 may be used for other applications. That is, if the winding body 100 is configured to be manufactured by winding a belt-like material that undergoes plastic deformation in part around the core 40, it may be used for applications other than the above. Also, the number of belt-like materials used for manufacturing the winding body can be set as appropriate. For example, it is preferable that there are two or more belt-like materials, but there may be one.

[0100] In addition, in the winding device 1, the arrangement relationship of the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104 that are conveyed and wound can be set as appropriate. Further, the innermost material (layer) where the folding line 100a of the wound body 100 is formed may be a separator or a current collecting foil (positive electrode sheet 101 and negative electrode sheet 103).

[0101] According to the core and the winding device of at least one of the embodiments described above, by having a pair of corner portions and a pair of outer peripheral surfaces, it is possible to suppress the looseness of the innermost material and reduce the acceleration and deceleration during rotation.

[0102] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and its equivalent scope. The following is an appended description equivalent to the invention described in the original claims of this application. [1] A bobbin around which a strip-shaped material is wound, having a pair of outer peripheral surfaces extending along a first central axis that is a rotation center and formed with a predetermined curvature radius, and a pair of corner parts extending along the first central axis at circumferentially symmetric positions. [2] The bobbin according to [1], wherein the angle of the tangent of the corner part is 120° or less. [3] The outer peripheral surface is formed with one curvature radius, The bobbin according to [1] or [2], wherein the center of curvature of the outer peripheral surface is in a direction orthogonal to each of the first central axis and a second central axis connecting the pair of corner parts, and is offset from the second central axis. [4] Having a pair of core pieces extending along the first central axis and each having the corner part, The pair of core pieces has slits inclined with respect to the second central axis, The bobbin according to [3], which holds the material disposed in the slits. [5] A winding device comprising the bobbin according to any one of [1] to [4], and a conveying part for conveying the material to the bobbin. ​

Claims

1. A pair of outer peripheral surfaces extending along a first central axis that is a rotation center and formed with a predetermined radius of curvature, and a pair of corner portions extending along the first central axis at symmetric positions in the circumferential direction, on which a strip-shaped material is wound around the outer peripheral surface, The angle of the tangent line of the corner portion is 120° or less, The outer peripheral surface is formed with a single radius of curvature, The center of curvature of the outer peripheral surface is in a direction orthogonal to each of the first central axis and a second central axis connecting the pair of corner portions and is offset from the second central axis, The outer peripheral surface is a curved surface formed with a single radius of curvature, and the center of curvature of the outer peripheral surface is arranged on the outer periphery of the paired outer peripheral surfaces, The corner portion is a core formed in a curved surface shape with a radius of curvature of 1 mm or less.

2. Having a pair of chip pieces extending along the first central axis and each having the corner portion, The pair of chip pieces has slits inclined with respect to the second central axis, The core according to claim 1, which holds the material disposed in the slits.

3. The core according to claim 1 or claim 2, and a conveying unit that conveys the material to the core, A winding device comprising: ​ ​ ​

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