A transformer includes a first winding arranged around an axis, and a second winding arranged around the axis. The second winding includes a litz wire having an end portion located at an axial end position of the second winding and a middle portion located at an axial middle position of the second winding. The litz wire has a first cross section at the end portion and a second cross section at the middle portion, the cross sections each including in a quadrant between the axial outward direction and the direction pointing towards the first winding a curvature extending between the axial outward direction and the direction pointing towards the first winding. The curvature of the first cross section is smaller than the curvature of the second cross section thereby reducing the peak magnitude of the electrical field between the end portion of the second winding and the first winding.

A coil includes: a wound conducting wire; and a terminal structure formed on an end of the conducting wire. The conducting wire is formed by bundling and twisting a plurality of strands. The strands are arranged longitudinally along a central axis of the coil. A method for manufacturing the coil includes: causing the end to pass through an internal space; then inserting a partition plate into a sleeve in a longitudinal direction so as to push the strands apart and arranging the strands in a first region and a second region; and then pinching the sleeve in a lateral direction and crushing the sleeve.

A coil includes: a wound conducting wire; and a terminal structure formed on an end of the conducting wire. The conducting wire is formed by bundling and twisting a plurality of strands. The strands are arranged longitudinally along a central axis of the coil. A method for manufacturing the coil includes: causing the end to pass through an internal space; then inserting a partition plate into a sleeve in a longitudinal direction so as to push the strands apart and arranging the strands in a first region and a second region; and then pinching the sleeve in a lateral direction and crushing the sleeve.

Disclosed is a method for manufacturing an MSO coil, comprising: a pressing step of forming a bent surface on a part of a unit coil layer, which has a ring shape such that both ends thereof face each other, thereby endowing both ends of the unit coil layer with a height difference; a fixing step of connecting and fixing a plurality of unit coil layers to each other, each unit coil layer having the bent surface formed thereon, such that the first end of both ends of a unit coil layer having the bent surface formed thereon contacts the second end of both ends of another unit coil layer having the bent surface formed thereon; and a bonding step of bonding connection parts defined by contact of the first and second ends of each of the plurality of unit coil layers that are connected and fixed to each other.

In a coil forming device, an edge line in an escape region is formed so that a clearance between the edge line in the escape region and a recess portion in an axis direction is larger than a minimum clearance between the edge line in an inclined region and the recess portion in the axis direction. When a second die is rotated relative to a first die in the clockwise direction the flat-square conductive material end is bent in flatwise bending by the recess portion and the inclined region of a protrusion portion, and then, the flat-square conductive material end reaches the escape region.

A coil-forming apparatus for forming a bare coil wire into a U-shape, the apparatus comprising: one bare coil-wire holding unit that winds and holds a bare coil wire; a take-up drum that includes one or a plurality of housing units that house the bare coil wire supplied from the one bare coil wire holding unit at a circumference; a cutting member that cuts the bare coil wire housed in housing units and wound around the take-up drum, at a portion of the circumference of the take-up drum; a drawing member for drawing the bare coil wire outward in a radial direction of the take-up drum after being cut by the cutting member, from a position separated from the cutting member; and a forming unit that forms the bare coil wire drawn by the drawing member into a U-shape.

A method of manufacturing a high-density coil formed by press working a coil to cope with the manufacture of high-density coils having various cross-sectional shapes. The method includes: a step of setting the coil at a predetermined press working position in a press working machine; and a step of sequential press working the coil, which is set at the predetermined press working position, in a plurality of directions sequentially with a time lag.

A bending device for a wire includes a holder including a stepped part, the stepped part includes a side-surface corner and a flat surface, and the side-surface corner includes a curved surface. The bending device includes a guide member configured to push the wire against and along the curved surface, and the guide member revolves around a rotational axis of the guide member. The rotational axis of the guide member is disposed on a same axis as a center of the circle defining the curved surface of the holder.

A bending device for a wire includes a holder including a stepped part, the stepped part includes a side-surface corner and a flat surface, and the side-surface corner includes a curved surface. The bending device includes a guide member configured to push the wire against and along the curved surface, and the guide member revolves around a rotational axis of the guide member. The rotational axis of the guide member is disposed on a same axis as a center of the circle defining the curved surface of the holder.

Disclosed is a method for manufacturing an MSO coil, comprising: a pressing step of forming a bent surface on a part of a unit coil layer, which has a ring shape such that both ends thereof face each other, thereby endowing both ends of the unit coil layer with a height difference; a fixing step of connecting and fixing a plurality of unit coil layers to each other, each unit coil layer having the bent surface formed thereon, such that the first end of both ends of a unit coil layer having the bent surface formed thereon contacts the second end of both ends of another unit coil layer having the bent surface formed thereon; and a bonding step of bonding connection parts defined by contact of the first and second ends of each of the plurality of unit coil layers that are connected and fixed to each other.