A core for a torque detection sensor includes a first laminated core in which first teeth are provided to protrude in a radial direction at plural places from an annular first core back formed by laminating a plurality of magnetic sheet materials, and a second laminated core in which second teeth are provided to protrude in the radial direction at plural places from an annular second core back formed by laminating a plurality of magnetic sheet materials, in which the first laminated core and the second laminated core are stacked so that the first teeth and the second teeth are in staggered arrangement in a circumferential direction.

This wound core (10) is a wound core (10) including a portion in which grain-oriented electrical steel sheets (1) in which planar'portions (4) and bent portions (5) are alternately continuous in a longitudinal direction are stacked in a sheet thickness direction and formed by stacking the grain-oriented electrical steel sheets (1) that have been individually bent in layers and assembled into a wound shape, wherein, when an average height of a roughness curve element in a width direction intersecting the longitudinal direction forming a surface of the bent portion (5) of the grain-oriented electrical steel sheet (1) is Ra(b) and an average height of a roughness curve element in a width direction forming ,a surface of the planar portion (4) of the grain-oriented electrical steel sheet (1) is Ra(s), the relationship of 1.00<Ra(b)/Ra(s)≤5.00 is satisfied.

A wound core (10) is a wound core having a wound shape (10) including a rectangular hollow portion (15) in a center and a portion in which grain-oriented electrical steel sheets (1) in which planar portions (4) and bent portions (5) are alternately continuous in a longitudinal direction are stacked in a sheet thickness direction, which is a wound core formed by stacking the grain-oriented electrical steel sheets(1) that have been individually bent in layers and assembled into a wound shape and in which the plurality of grain-oriented electrical steel sheets are connected to each other via at least one joining part (6) for each roll, wherein the bent portion (5) of the laminated grain-oriented electrical steel sheet (1) has an average Vickers hardness of 190 to 250 HV in an L cross section in the longitudinal direction which is a cross section of the grain-oriented electrical steel sheet (1) in a thickness direction.

This wound core is a wound core including a substantially rectangular wound core main body in a side view, wherein, in the wound core main body, first planar portions and corner portions are alternately continuous in a longitudinal direction, each corner portion has a curved shape in a side view of the grain-oriented electrical steel sheet, two or more bent portions having a second planar portion between the adjacent bent portions are provided, and in at least one of the first planar portion and second planar portion in the vicinity of the bent portion, the following Formula (1) is satisfied:

(Nac+Nal)/Nt≥0.010  (1) here, Nt is a total number of grain boundary determination locations in the first planar portion and second planar portion region adjacent to the bent portion, and Nac and Nal each are a number of determination location at which subgrain boundaries are able to be identified in a direction parallel to and direction perpendicular to the bent portion boundary.

In this method of producing a wound core, at least one bent portion (5) of one or more laminated grain oriented electrical steel sheets (1) is formed such that one side (1b) of the steel sheet (1) is placed and constrained on a die (30) and a punch (40) is press formed against a portion (1a) of the steel sheet (1) to be bent on the other free end side in the thickness (T) direction of the steel sheet. Outer surfaces of the die and the punch each have an arc portion (30a, 40a) having a predetermined curvature, and when the thickness of the steel sheet (1) is T, bent angles of the bent portions (5) are θ(°), a radius of curvature of the arc portion (30a) of the die is Rd, and a radius of curvature of the arc portion (40a) of the punch is Rp, relationships of Equations (1) to (5) below are satisfied.

0.02≤T/(2Rd+T)≤0.15   (1)

0.5 ≤Rd ≤3.0   (2)

0.15 ≤T ≤0.30   (3)

2.5≤Rp/Rd≤10   (4)

10°≤θ≤90°  (5)

A wound core equipped with a laminated body including plural electrical steel sheets stacked in a ring shape in side view. The laminated body includes plural bent portions, and plural block-shaped portions at positions between adjacent bent portions. At least one bent portion among the plural bent portions is a high stacking factor bent portion, wherein a stacking factor of the electrical steel sheets at the high stacking bent portion is higher than an average stacking factor of the steel sheets at the plural block-shaped portions.

This wound core is a wound core including a wound core main body obtained by stacking a plurality of polygonal annular grain-oriented electrical steel sheets in a side view, and the grain-oriented electrical steel sheet has planar portions and bent portions that are alternately continuous in a longitudinal direction, and in a planar portion in the vicinity of at least one bent portion, when the three-dimensional crystal orientation difference between two adjacent points in a series of points arranged at equal intervals in the extension direction of the bent portion is φ, a total number of measured data items of φ is Nx, the number of data items that satisfy φ≥1.0° is Nt, the number of data items that satisfy φ of 1.0° or more and less than 2.5° is Na, the number of data items that satisfy φ of 2.5° or more and less than 4.0° is Nb, and the number of data items that satisfy φ of 4.0° or more is Nc, the following formulae (1) to (4) are satisfied:

0.10≤Nt/Nx≤0.80  (1)

0.37≤Nb/Nt≤0.80  (2)

1.07≤Nb/Na≤4.00  (3)

Nb/Nc≥1.10  (4)

A wound core (10) in which, in a laminating direction, when the surface roughness of a steel sheet portion in a direction connecting a center in a sheet thickness direction of a grain-oriented electrical steel sheet (1) positioned on the innermost periphery of the wound core among the laminated grain-oriented electrical steel sheets (1) and a center in the sheet thickness direction of the grain-oriented electrical steel sheet (1) positioned on the outermost periphery of the wound core (10) is Ral, and the surface roughness of the grain-oriented electrical steel sheet (1) in a direction parallel to a longitudinal direction on an end surface of a planar portion (4) of the laminated grain-oriented electrical steel sheet (1) is Rac, a ratio Ral/Rac between Rat and Rac satisfies the relationship of 1.5≤Ral/Rac≤12.0.

Provided is a wound core having a flat portion and corner portions adjacent to the flat portion, the flat portion including a lap portion, the corner portions including bent portions. A non-heat-resistant magnetic domain refined material is used for at least a part of the materials forming the wound core. Closure domains are formed in the non-heat-resistant magnetic domain refined material so as to extend in a direction intersecting a longitudinal direction of the non-heat-resistant magnetic domain refined material, an area of each of the closure domains in a cross section that is taken in the longitudinal direction being more than 7500 μm.sup.2. In the lap portion, the ratio of the number of lap joint portions having a lap length of from 3.0 mm to 30 mm to the total number of lap joint portions is 50% or more.

The present invention provides a magnetic core and transformer which are reduced in core loss.

The magnetic core according to the present invention comprises a core member which is formed by winding first electrical steel sheets, which is ring shaped seen from a side surface, and which has one or more bent parts seen from a side surface and one or more stacks of second electrical steel sheets stacked together, each the stack being arranged at least at one of the surfaces formed by side surfaces of the first electrical steel sheets at a bent part of the core member so that a surface formed by side surfaces of the second electrical steel sheets runs along it.