JPH11135319A - Method for taking-up double-pancake coil and coil forming device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for taking-up a double-pancake coil by which a double-pancake coil can be formed easily. SOLUTION: A double-pancake coil A is formed, in such a way that a coil wire rod 1 temporarily wound in a cylindrical state is divided into two parts at the middle section, and a first-layer coil section A1 is formed by drawing out one part of the wire rod 1 from the middle section to one end by changing the curvature of the wire rod 1 by means of a bending mechanism 33 and spirally winding the part, while the shape is maintained from the inner peripheral side in the same plane. When the formation of the first-layer coil section A1 is completed, the section A1 is inverted upside down and a second-layer coil section A2 is formed by winding the other part of the wire rod 1 from the middle section to the other end upon the first-layer coil section A1 while the shape is maintained from the inner peripheral side by similary changing the curvature of the wire rod 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double pancake coil winding method used for forming, for example, a coil for storing a superconducting power and a coil forming apparatus using the method.

[0002]

2. Description of the Related Art For superconducting power storage coils and the like, the development of a pancake coil has been developed. Conventionally,
The molding of this pancake-shaped coil is disclosed in
As disclosed in Japanese Patent Publication No. 26, there is proposed a method of forming an object b in which a coil wire in which an outer peripheral portion of a conductive wire is covered with a metal pipe is temporarily wound into a cylindrical shape into a pancake shape.

[0003] Specifically, as shown in Figs. 10 and 11, a coil wire a
The electric wire drum b (which is formed by covering the outer peripheral portion of the conductive wire with a metal pipe) is wound in a cylindrical shape.
The coil wire rod a is set on the rotary table c and spread horizontally on a temporary coil base d provided around the rotary table c.
After the step of fixing the outer peripheral end of the wire to the temporary coil placement base d, the electric wire drum b is removed. After that, the developed coil wire a is wound on the winding core e provided on the rotary table c.
After the inner peripheral end of the coil is fixed, a method of forming the coil into a pancake shape by rotating the winding core e in a direction in which the coil is tightened by the rotation driving unit f of the rotary table c is adopted. I have.

[0004]

By the way, in the superconducting power storage coil, in order to obtain higher performance, not only a pancake shape but upper and lower coils (first and second layer coil portions) are arranged from the center. A double pancake-shaped coil that can be wound around the outer periphery while rotating in the opposite direction has been required.

[0005] However, after the coil wire a having the cylindrical shape temporarily wound as described above is developed in a horizontal spiral shape, the coil is tightened by rotation of a winding core mold e provided at the center. With the winding method, it is very difficult to form a coil in which the upper and lower coils are wound in opposite directions from the center, such as a double pancake coil.

Therefore, there is a demand for a technique suitable for forming a double pancake coil. The present invention has been made in view of the above circumstances, and an object thereof is to use a double pancake coil winding method and a double pancake coil winding method capable of easily forming a double pancake coil which is considered difficult. An object of the present invention is to provide a coil forming device.

[0007]

According to a first aspect of the present invention, in order to achieve the above object, a wire rod temporarily wound in a cylindrical shape is separated from an intermediate portion, and a wire rod on one end side from the intermediate portion is separated. The wire is fed out while changing the curvature of the wire rod by the bending mechanism, and is wound in a spiral shape while maintaining the shape from the inner peripheral side on the same plane to form the first coil portion.When the formation of the first coil portion is completed, The coil portion is inverted, and the wire from the intermediate portion to the other end is wound in a spiral shape while maintaining the shape from the inner peripheral side while changing the curvature of the wire in the same manner as described above while overlapping the first coil portion. By adopting the double pancake coil winding method of forming the coil portion of the layer, a double pancake-shaped coil can be directly formed from a coil temporarily wound in a cylindrical shape.

According to a second aspect of the present invention, the bending mechanism
Forming is performed by feeding the wire so as to change the wire curvature to a curvature larger than a predetermined curvature at an inner peripheral portion of the coil portion, a predetermined wire curvature at a central portion, and a curvature smaller than a predetermined wire curvature at an outer peripheral portion. Even if the finished double pancake-shaped coil is in a free state, the shape does not change. That is, after the formation of the double pancake-shaped coil is completed, even if the coil is removed from the core portion, the spiral shape is not broken.

According to a third aspect of the present invention, in order to achieve the above object, there is provided a coil set section for setting a wire rod temporarily wound in a cylindrical shape from an intermediate portion and setting each at a point separated in an axial direction, The core provided between the coil set portions and a wire from the intermediate portion to one end are fed out while changing the wire curvature, and the wire is wound around the core while maintaining a spiral shape on the same plane. It has a winding mechanism and a posture changing portion for reversing the first spiral coil portion that has been wound around the core portion, and superimposes the inverted first coil portion, from the remaining intermediate portion to the other end portion. By adopting a coil forming device that spirally winds the wire around the core with a winding mechanism and forms the coil part of the second layer, the coil that has been temporarily wound into a cylindrical shape can be used to convert the coil into a double pancake shape. I can do molding It was.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on one embodiment shown in FIGS. 1 and 2
Shows the outer shape and cross-section of a double pancake-shaped coil A, for example, for storing super-power, formed by the method of the present invention.

The shape of the double pancake-shaped coil A is such that the coil wire 1 starts to be wound from the outermost periphery on the upper surface side, is sequentially wound in a spiral shape on the inner periphery, shifts to the lower surface side at the innermost periphery, and then moves to the upper surface side. And spirally wound toward the outer periphery in the same direction as the above, and ends at the outermost periphery. Note that, for the coil wire 1, for example, a wire having a rectangular cross section in which the outer peripheral portion of the conductive wire is covered with a metal pipe (both not shown) is used.

FIGS. 4 and 5 show a forming apparatus for forming the double-cake coil A. Describing the structure of the molding apparatus, FIG. 4 is a sectional side view of each section of the molding apparatus, and FIG. 5 is a side view of the molding apparatus, and 10 is a base.

At the center of the upper surface of the base 10, for example, a column-shaped central shaft 11 is erected. A rotating shaft 13 formed into a cylindrical shape is rotatably attached to the middle outer peripheral surface of the center shaft 11 via, for example, a pair of upper and lower bearings 12. A gear portion 13a is formed on the outer periphery of the lower portion of the rotating shaft 13. The gear portion 13a meshes with a pinion gear 14b of a rotating shaft driving portion 14 constituted by, for example, a motor 14a equipped with a speed reducer mounted on the upper surface of the base 10, and uses the rotating shaft driving portion 14 as a power source to rotate the rotating shaft 13a. Can be rotated horizontally.

An annular step 15 formed on the outer periphery of the upper end of the rotating shaft 13 is provided with a coil-wound core 16 (equivalent to a core, hereinafter simply referred to as a core) formed in a disk shape having a vertically symmetrical shape. (Referred to as gold). The metal core 16 penetrates the metal core 16 from above, and the step 15
Of the rotating shaft 1 by the bolt member 17 screwed into the lower surface of the
3 is detachably fixed. Further, by this fixing structure, the metal core 16 is attached to the step portion 15 of the rotating shaft 13 in an upside-down direction (corresponding to a posture changing portion).

An annular seat portion 16a protruding from the outer peripheral end of the metal core 16 is provided with a short strip plate mounting piece 18 on the upper side and a U-shaped receiving frame 19 opened upward on the lower side. A plurality of base pieces 20 are detachably mounted radially.

Specifically, the mounting table piece 18 and the receiving frame 19 are fastened to each other by a fastening member, for example, a bolt member 21.
The base piece 20 is such that the inner peripheral ends of the mounting piece 18 and the receiving frame 19 which are arranged in an L-shape are fitted into the lower corners of the seat 16a, and penetrate the end of the receiving frame 19 from below. hand,
It is detachably fixed to the metal core 16 by a bolt member 22 screwed into the lower surface of the seat 16a.

[0017] The coil 18 is spirally arranged on the same plane around the metal core 16 with the metal core 16 as a core (center) by means of the mounting pieces 18 arranged radially by assembling the base piece 20. A winding base 23 for winding is formed. Further, immediately below (on the lower side of) the winding base 23, the lower side of the coil L obtained by temporarily winding the coil wire 1 into a cylindrical shape and separated from the intermediate portion is accommodated by a receiving frame 19 arranged radially. A lower temporary winding coil temporary holder 24 (hereinafter referred to as a lower holder) is formed.

A coil holding plate 26 (shown only in FIG. 9) is attached to the opposite side (upper side) of the seat 16a by using a vertical screw hole 25 formed in the seat 16a. The first coil part A1 wound spirally above
It can also be fixed.

A plurality of support rollers 28 for coil placement are provided on the outer periphery of the upper end of the
Are radially attached, and the upper coil portion of the temporarily wrapped cylindrical coil L divided from the intermediate portion is installed on the opposite side of the lower placing table 22 across the metal core 16 so as to be able to be fed out. Temporary coil winding temporary storage part 29
(Hereinafter, referred to as an upper placing part).

Then, the upper / lower sides of the cylindrical coil L divided by the middle part are respectively separated from the upper placing part 29 and the lower placing stand 24 disposed at the points sandwiching the cored bar 16 at points separated in the axial direction. A coil setting section 30 for setting is configured. That is, after the coil L temporarily wound in a cylindrical shape is placed on the upper placing portion 29, the end of the coil wire 1 is guided from the lower end of the cylindrical coil L by the feeding guide roller 31 provided on the arm 27. Through the gap between the table pieces 18 to the lower table 24, and by rotating the rotary shaft 13 to transfer half the amount of the cylindrical coil L from the upper table 29 to the lower table 24, the intermediate section is used. The upper half of the divided cylindrical coil L is set on the upper holder 29, and the lower half is also set on the lower holder 24. In particular, the upper placing portion 29 employs a coil placing supporting roller 28 so that the coil wire 1 can be paid out without any load when the coil wire 1 is pulled.

On the other hand, a coil bending mechanism 33 is installed on the outer peripheral side of the upper surface of the base 10 via a support 32.
The coil bending mechanism 33 is supported just above the winding base 23 so as to be movable in the radial direction by a slide mechanism 34 interposed between the coil bending mechanism 33 and the support table 32. The coil bending mechanism 33 employs a structure in which the coil wire 1 is fed from the upper placing portion 29 while changing the wire curvature, for example, a structure using a three-point roller system.

The structure of the three-point roller type coil bending mechanism 33 is shown in FIGS. The coil bending mechanism 33 has, for example, an advance / retreat mechanism that can advance / retreat toward the center of the winding base 23, for example, a cylinder mechanism 35 including a hydraulic cylinder or the like. The cylinder section 35a of the cylinder mechanism 35 is installed on the movable base 34a of the slide mechanism 34.

The forward / backward rod 3 which advances / retreats the cylinder portion 35a
A bending roller 36 is mounted laterally at the tip of 5b. A pair of receiving rollers 38 are mounted laterally on both sides of the bending roller 36 via a roller holder 37 at the tip of the cylinder portion 35a. That is, the rollers 36 and 38 are arranged at points that become the vertices of the triangle. Further, each receiving roller 38 is provided with a wire feeder installed on the roller holder 37, for example, the gear box 3
9 is rotated by a feeder 42 which is a combination of a wire feed motor 40 with a gear 9 and a gear type transmission mechanism 41 for transmitting an output from a gear box 39 to a receiving roller 38.

Thus, the coil bending mechanism 33 is brought closer to the intermediate portion of the cylindrical temporary winding coil by the slide mechanism 34, and the coil wire 1 in the intermediate portion is moved to two bending rollers 36 and one bending roller 38. Then, the position of the bending roller 36 is changed by the advance and retreat of the cylinder mechanism 35 (the forward and backward rod 35b), and the receiving roller 38 is driven to rotate. The coiled wire 1 can be fed out while changing the curvature of the wire sequentially.

When the coil wire 1 is fed, the rotation drive unit 14 is operated to rotate the metal core 16, the winding base 23, and the lower table 24 together. Thus, the coil wire 1 fed by the three-point roller coil bending mechanism 33 is wound around the core 16 in a spiral shape. That is, the coil wire 1 from the intermediate portion to one end is spirally wound on the same plane. By this winding, the first coil portion A1 is formed.

A coil outer circumference pressing mechanism 45 and a coil flat surface pressing mechanism 50 are installed on the outer peripheral side of the upper surface of the base 10. The coil outer peripheral holding mechanism 45 is, for example, a cylinder mechanism 47 installed on a support base 46, and as shown in FIG. 6, a coil outer peripheral pressing roller 48 composed of a vertical roller is wound while the coil is being wound (forming). Wire rod 1
From the outer peripheral side, and during coil winding,
The coil is prevented from expanding toward the outside diameter.

The coil flat pressing mechanism 50 has a coil flat pressing roller 52 for pressing the flat surface of the coil wound spirally on the winding base 23. Then, the coil flat pressing mechanism 50 and the coil outer pressing roller 4
In combination with 8, the coil wire 1 constitutes a guide structure for winding the coil wire 1 around the cored bar 16 in a spiral shape while keeping the wires in close contact with each other. Reference numeral 51 denotes a support for mounting the coil flat pressing roller 52 on the base 10.

The coil outer circumference holding mechanism 45 and the coil flat surface holding mechanism 50 are combined with the above-mentioned winding structure, so that the coil wire 1 can be spirally wound on the same plane while maintaining its shape from the inner circumference side. Make up the mechanism. Note that, for example, the coil outer peripheral pressing mechanism 45 and the coil flat pressing mechanism 50 are configured to be retractable so that the coil outer pressing roller 48 and the coil flat pressing roller 52 are removed from the area of the winding base 23.

When the forming (winding) of the first coil portion A1 is completed, the coil portion A1 is fixed using the coil holding plate 26, the washer 16 is turned upside down by 180 °, and the rotating shaft 13 is turned. Then, the mounting table piece 18 is removed from the metal core 16 together with the receiving frame 19, and the coil wire 1 from the remaining intermediate portion to the other end is rotated by the rotation shaft 13 in reverse.
After being wound around the coil supporting roller 28, the three-point roller type coil bending mechanism 33, the winding base 23, the coil outer circumference holding mechanism 45, and the coil plane holding mechanism 5
In the same step as forming the first coil portion A1 using the coil wire 0, the coil wire 1 from the remaining intermediate portion to the other end portion is formed.
Is coiled around the core 16 around the coil portion A1 to form a coil portion A2 of the second layer.

A three-point roller type coil bending mechanism 33
Changes the curvature of the wire to a curvature greater than a predetermined curvature at the inner periphery of the first and second layers of the coil portions A1 and A2, a curvature of the predetermined wire at the center, and a curvature smaller than the curvature of the wire at the outer periphery. The coil wire 1 is set so as to be fed out. For example, as shown in FIG. 3, of the coil portions A1 and A2 of the first / second layer, in the inner peripheral portion indicated by reference numeral C,
The position of the bending roller 36 is set so as to obtain a wire curvature approximately 5 to 10% larger than the predetermined wire curvature, and a predetermined wire curvature (for example, a cylindrical coil L
In the outer peripheral portion indicated by reference symbol E, the position of the bending roller 36 is set so as to obtain a wire curvature that is smaller by about 5 to 10% than a predetermined wire curvature. However, a spiral coil whose shape does not change is formed.

Next, a double pancake coil winding method will be described based on the operation of the coil forming apparatus. First, a coil L1 temporarily provisionally wound in a cylindrical shape is prepared, and is divided from an intermediate portion (a central portion in the axial direction), and is separated from an upper placing portion 29.
And the lower table 24.

In this operation, the entirety of the coil wire 1 temporarily wound into a cylindrical shape is placed on an upper placing portion 29, that is, a plurality of rotatable coil placing supporting rollers 28, and is fed out from a lower end portion thereof. Between the mounting table pieces 18 (those that constitute the winding base 23)
Through the gap to the lower table 24 composed of the receiving frame 19. Then, the rotation shaft driving unit 14 is driven to transfer half the amount of the cylindrical col to the lower placing table 24, and is stored in the lower placing table 24.

From this state, molding of the coil portion A1 of the first layer starts. For this, first, for example, the three-point roller bending mechanism 33 retracted to a position separated from the winding base 23 is used.
Is advanced, and the three-point roller portion is brought closer to the coil wire 1 at the intermediate portion (central portion) passing between the upper placing portion 29 and the lower placing stand 24.

Then, the coil wire 1 at the intermediate portion is passed through the three-point roller portion. Specifically, as shown in FIGS. 6 and 7, the intermediate coil wire 1 is passed between the two receiving rollers 38 and the bending roller 36.

Next, a three-point roller type coil bending mechanism 3
The curvature of the coil wire 1 is determined by moving the third cylinder mechanism 35 forward and backward. Subsequently, the wire feed motor 40 of the three-point roller coil bending mechanism 33 is operated.

Then, the upper half of the cylindrical coil L on the upper placing portion 29 is divided into the receiving roller 38 and the bending roller 36.
While being bent under the restriction of the above, it is fed out to the cored bar 16.

Here, the rotating shaft drive unit 14 operates together with the wire feed motor 40, and rotates the metal core 16, the winding base 23, and the lower stand 24 integrally. Thereby, the coil wire 1 is wound around the cored bar 16 by the amount sent out by the three-point roller type coil bending mechanism 33.

At this time, the coil outer circumference pressing mechanism 45 and the coil flat surface pressing mechanism 50 are arranged at predetermined positions, and the coil outer circumference roller 48 controls the wound coil wire 1 from the outer circumference so as not to expand by pressing. The flat pressing roller 52 presses the wound coil wire 1 from above and regulates it so as to be flat.

Then, from the intermediate portion of the coil wire 1 to the upper end of the cylindrical coil L placed on the upper placing portion 29,
The core 16 is spirally wound on the same plane, that is, along the winding base 23, so that the lines are close to each other.

Here, the three-point roller type coil bending mechanism 3
3, when winding the inner peripheral portion of the coil portion A1, the position of the bending roller 36 is set so as to obtain a wire curvature that is about 5 to 10% larger than a predetermined wire curvature, and when winding the central portion of the coil portion A1, The position of the bending roller 36 is set so as to obtain a predetermined wire curvature (for example, a wire curvature equivalent to that of a cylindrical coil), and when winding the outer peripheral portion of the coil portion A1, it is 5 to 5 degrees larger than the predetermined wire curvature.
Since the position of the bending roller 36 is set so as to obtain a wire curvature smaller by about 10%, the coil wire 1 is fed out while changing the curvature sequentially.

As a result, the coil wire 1 is given a curl (bend) in the direction of bringing the wires into close contact with each other, and the first pancake-shaped coil portion A1 having a large shape retaining force is formed.

After the molding of the first layer coil portion A1 is completed, the molding of the second layer coil portion A2 is started. At this time, the core metal 16 is wound around the coil portion A1,
Change the posture to 180 ° upside down.

First, the coil holding plate 26 is placed on the mounting piece 18 so as to sandwich the first coil portion A1 from above, and the coil holding plate 26 is mounted on the mounting table 18 and the receiving frame 19.
Is fastened to the metal core 16 using the screw holes 25 fixing the
The first coil part A1 is fixed. Reference numeral 53 denotes a bolt member 53 for fixing the coil holding plate 26 (shown only in FIG. 9).

Next, the bolt member 17 fixing the rotating shaft 2 and the core 16 is once removed, and the rotating shaft 13 is pulled out from the stepped portion 15, and the rotating shaft 13 is turned upside down, that is, the coil pressing plate 26. Is fixed to the step portion 15 again and fixed by the bolt member 17.

Subsequently, the lower placing table 24 (receiving frame 19) is removed from the metal core 16 together with the placing table piece 18. Thereafter, the lower half of the cylindrical coil housed in the lower placing table 24 (the receiving frame 19) is formed by the coil supporting roller 28 through the feeding guide roller 31 by the rotation driving of the rotation driving unit 14 in the reverse direction. Is wound up on the upper placing portion 29 to be set.

Thus, the posture for winding the coil portion A2 of the second layer is set. Thereafter, in the same step as the step of forming the first coil part A1, the three-point roller type coil bending mechanism 33, the coil outer circumference holding mechanism 45,
As shown in FIG. 9, the coil flat holding mechanism 50 and the rotating shaft 13 are used to overlap the coil portion A1 as shown in FIG. As shown in FIGS. 1 and 2, a double pancake coil A is formed in which the upper and lower coil portions A1 and A2 are wound around the outer periphery while rotating in opposite directions from the center.

Thus, the coil wire 1 on one end side is drawn out from the middle part of the cylindrical coil L divided vertically and wound spirally to form the first-layer (first surface) coil portion A1, and then the coil portion A1 is formed. And the coil wire 1 from the intermediate portion to the other end remaining on the coil portion A1 is spirally wound from the inner peripheral side while changing the wire curvature similarly to form the coil portion A2 of the second layer (first surface). The double pancake-shaped coil A, which has been considered difficult, can be easily formed by the winding method and the forming apparatus for forming. In particular, the coil wire 1 to be fed out is regulated by the coil outer circumference pressing roller 48 and the coil flat surface pressing roller 52 so as to be wound in a spiral shape while maintaining the shape. Deformation such as unevenness does not occur.

Further, when the pancake coil is formed, the coil wire 1 is fed out while changing the curvature of the coil wire 1, so that a good spiral coil can be formed. In particular, since the curvature of the wire at this time was changed to a curvature larger than the predetermined curvature at the inner periphery of the coil portions A1 and A2, a predetermined wire curvature at the center portion, and a smaller curvature at the outer periphery than the predetermined wire curvature, Even if the double pancake-shaped coil that has been formed is removed from the core after the double pancake-shaped coil is in a free state, that is, after forming the double pancake-shaped coil, there is no change in the shape, that is, the spiral shape does not collapse.

In addition, the coil wire 1 to be fed is set on the support roller 28, so that the coil wire 1 is smoothly wound. Note that, in one embodiment, a structure using a three-point roller for the bending mechanism is adopted, but the present invention is not limited to this, and another structure may be adopted.

In one embodiment, the forming of the superconducting power storage coil is described as an example. However, the forming of a double pancake coil used for other purposes may be performed. Of course, the coil wire to be used is not limited to a wire having a conductive wire in a metal pipe, but may be a wire having another structure.

[0051]

As described above, according to the coil winding method and the coil forming apparatus of the present invention, it is possible to easily form a coil having a double pancake shape, which has been conventionally difficult.

Moreover, when forming the double pancake coil, the inner peripheral portion of the coil portion has a curvature larger than a predetermined curvature, the central portion has a predetermined wire curvature, and the outer peripheral portion has a smaller curvature than the predetermined wire curvature. By feeding the wire so as to change the curvature, the shaped double pancake coil does not lose its shape even in a free state.

[Brief description of the drawings]

FIG. 1 is a view showing an outer shape of a double pancake coil according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the double pancake-shaped coil along the line XX in FIG.

FIG. 3 is a cross-sectional view for explaining a portion where a curvature changes during molding of a double pancake coil.

FIG. 4 is a cross-sectional view showing a structure of a forming apparatus for forming a double pancake coil.

FIG. 5 is a side view of the same.

FIG. 6 is a perspective view for explaining the concept of a method of forming a double pancake coil.

FIG. 7 is a partially sectional plan view for explaining the structure of a three-point roller coil bending mechanism for changing the curvature of the coil wire.

FIG. 8 is a sectional view taken along the line Y-Y in FIG. 7 for explaining the payout structure of the coil bending mechanism.

FIG. 9 is a cross-sectional view illustrating a state when the second-layer coil portion is formed by the forming apparatus.

FIG. 10 is a view showing a conventional molding apparatus for molding a pancake-shaped coil, together with a step of placing an original coil and transferring it to a base.

FIG. 11 is a diagram showing a step of rotating the inner peripheral side of the transferred coil in a direction in which the coil is tightened.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Coil wire material 11 ... Center axis 13 ... Rotating axis 15, 17 ... Step part, bolt member (posture change part) 16 ... Core metal (core part) 23 ... Wounding base 25 ... Lower temporary placement coil temporary placement stand 26 ... Coil presser plate 29: Temporary coil winding temporary storage section 30: Coil set section 33: Coil bending mechanism 36: Bending roller 38: Receiving roller 45: Coil outer circumference holding mechanism 50: Coil flat surface holding mechanism A: Double pancake coil A1 ... First layer coil part A2 ... First layer coil part.

Claims (3)

[Claims] 1. A wire rod temporarily wound in a cylindrical shape is separated from an intermediate portion, and a wire at one end side is fed out from the intermediate portion while changing the curvature of the wire rod by a bending mechanism, and the shape is formed from the inner peripheral side on the same plane. The first coil portion is formed by spirally winding while holding the coil portion. When the formation of the first coil portion is completed, the coil portion is turned over, overlapped with the first coil portion, and the other portion from the intermediate portion. A double pancake coil winding method, wherein the end-side wire is spirally wound while maintaining its shape from the inner peripheral side while changing the wire curvature in the same manner as described above to form a second-layer coil portion. . 2. The bending mechanism according to claim 1, wherein the first and second layers have a curvature larger than a predetermined curvature at an inner peripheral portion, a predetermined wire curvature at a central portion, and a smaller curvature at a peripheral portion than a predetermined wire curvature. 2. The double pancake coil winding method according to claim 1, wherein the wire is fed out so as to change the curvature of the wire. 3. A coil set portion for separating a wire temporarily wound into a cylindrical shape from an intermediate portion and setting each at a position separated in an axial direction, a core portion provided between the coil set portions, and an intermediate portion. A winding mechanism for feeding the wire to one end while changing the wire curvature, winding the wire around the core while maintaining a spiral shape on the same plane, and finishing the winding to the core A posture changing portion for reversing the first-layer spiral coil portion, wherein the wire material from the intermediate portion to the other end portion is superimposed on the inverted first-layer coil portion, and is wound around the core portion by the winding mechanism. A coil forming apparatus characterized by forming a coil portion of a second layer by winding in a coil shape.