Inner and outer double-coil structure and winding method thereof
Through the combination of the internal and external dual coil structure and the adjustable winding die, the problem of easy cracking of welding connections is solved, and efficient and low-cost multi-layer coil winding is achieved, which improves the coil's short-circuit resistance and space utilization.
Patent Information
- Application Number
- CN202510667879.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-23
- Publication Date
- 2025-07-25
AI Technical Summary
In the existing multi-layer coil winding method, welding connections cause welding joints to easily crack, pose a risk of short circuit, and are low in production efficiency, making it difficult to meet the space utilization and electrical performance requirements of miniaturized equipment.
It adopts a dual coil structure inside and outside, through uninterrupted winding and U-shaped connection, combined with an adjustable winding die and a strap-paper barrel structure, it realizes welding without joints, and enhances the coil's short-circuit resistance and space utilization.
The solderless joint winding of multi-layer coils is realized, which reduces the risk of welding joint cracking, improves production efficiency and mechanical strength of the coil, simplifies the process flow, and reduces costs.
Smart Images
Figure CN120376305A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of transformer manufacturing, and particularly relates to an internal and external double-coil structure and a winding method thereof. Background Art
[0002] With the rapid development of the power industry, small distribution transformers and switching reactors, as core components of the power system, have put forward higher requirements for the compactness, mechanical strength, and electrical performance of their coil structures.
[0003] In the existing multi-layer coil winding methods, the winding process generally adopts the method of segmental winding and then welding the wire tails to connect the inner and outer layer coils. The electrical connection of the inner and outer layer coils usually needs to be led out through copper strips and then welded or riveted, resulting in a complex coil end structure and an increase in redundant solder joints. At the same time, the welding process has significant defects: the solder joints are prone to cracks due to mechanical stress or temperature rise effects, leading to an increase in the local resistance of the coil or even an open circuit fault. In addition, the welding process relies on manual operation, with high process complexity and difficult to guarantee the consistency of solder joints. Especially in the scenario of welding operations in a small space, the spatial constraints of the solder joint positions further increase the process difficulty and cost of welding. Research shows that under the conditions of transformer short-circuit impact or frequent start-stop, the solder joints are prone to fatigue fracture due to electromagnetic force or thermal cycle stress, becoming a high-incidence weak point of equipment failures, seriously affecting the operation life and safety of the equipment.
[0004] Currently, the research on multi-layer coil winding technology mostly focuses on material optimization or insulation design, and insufficient attention is paid to the innovation of coil winding structures. In addition, the layer-changing winding of multi-layer coils in traditional processes requires repeated adjustment of the wire path, which is not only inefficient but also prone to inter-turn insulation damage due to manual operation errors.
[0005] In view of the above technical problems, how to achieve solderless integrated winding of multi-layer coils in a limited space, while improving the short-circuit resistance and production efficiency of the coils, has become a technical problem that urgently needs to be broken through in this field. Therefore, it is necessary to design a new multi-layer coil winding structure and winding process method to fundamentally eliminate the risk of wire solder joints through topological optimization, simplify the production process, and meet the stringent requirements of small-sized equipment for space utilization. Summary of the Invention
[0006] In order to solve the above technical problems, the present invention provides an internal and external double-coil structure, and the technical solution adopted by the present invention is as follows: An internal and external double - coil structure includes an outer - layer coil and an inner - layer coil sleeved at the inner - center position of the outer - layer coil. The inner - layer coil includes coil P4 and coil P3. Coil P4 and coil P3 are continuously wound by several wires without interruption. The wires at the lower ends of coil P4 and coil P3 are bent into a U - shaped connection structure, and the wires at the upper ends of coil P4 and coil P3 are bent to lead out the upper - part leads of the coil. The outer - layer coil includes coil P2 and coil P1. Coil P2 and coil P1 are continuously wound by several wires without interruption. The wires at the lower ends of coil P2 and coil P1 are bent into a U - shaped connection structure, and the wires at the upper ends of coil P2 and coil P1 are bent to lead out the upper - part leads of the coil. At the tops of coil P2, coil P1, coil P4, and coil P3, upper - end rings for flattening the top of the coil are respectively arranged. The upper - end rings are provided with notches. At the bottoms of coil P2, coil P1, coil P4, and coil P3, several lower pads for flattening the bottom of the coil and evenly distributed circumferentially are respectively arranged.
[0007] Preferably, coil P2 and coil P4 are wound in a right - hand winding direction of the wire, and coil P3 and coil P1 are wound in a left - hand winding direction of the wire.
[0008] Preferably, the bottom of the upper - end ring is a spiral structure matching the top of the coil, the upper part of the upper - end ring is a horizontal structure, the end of the upper - end ring is processed into a chamfered structure, and the thickness of the upper - end ring is the same as the thickness of a single - layer coil.
[0009] Preferably, the material of the upper - end ring is sulfate paper.
[0010] Preferably, the top of the lower pad is a slope structure matching the bottom of the coil, the bottom of the lower pad is a horizontal structure, the thickness of the lower pad is the same as the thickness of a single - layer coil. The lower pads are placed on both sides of the lower - part leads of the coil, and a whole - circle PET tape is tied and set on the outer circumference surrounded by the lower pads.
[0011] Preferably, the material of the lower pad is laminated cardboard.
[0012] Preferably, the outer - layer coil is sleeved on the outer circumference of the insulating paper tube on the iron - core column. Coil P2 and coil P4 are close to the iron - core column. Several circumferentially - evenly distributed braces are arranged between the insulating paper tube on the iron - core column and coil P2. Several circumferentially - evenly distributed braces are arranged on the outer circumference of coil P1. Several paper tubes are sleeved between coil P4 and coil P2, between coil P4 and coil P3, and between coil P3 and coil P1. Several circumferentially - evenly distributed braces are arranged between adjacent paper tubes and between the paper tubes and the coils. Casein glue is spot - applied to the side surfaces of the braces adjacent to the paper tubes.
[0013] Preferably, the bent part of the wire is wrapped with crinkled paper.
[0014] The winding method of the aforementioned internal and external double - coil structure includes the following steps: A number of support bars are evenly arranged on the outer circumference of the insulating paper tube on the outer side of the iron core column. The support bars are adhesively fixed by spot-applying casein glue to the side surfaces adjacent to the insulating paper tube on the outer side of the iron core column. The coil P2 is wound around the insulating paper tube on the outer side of the iron core column and the support bars in a right-handed descending layer winding manner from top to bottom. After the winding of the coil P2 is completed, the wires used for winding the coil P1 are respectively wound around the adjustable winding mold one by one; A number of layers of support bar - paper tube are arranged on the outer circumference of the coil P2. A number of support bars are arranged on the outer circumference of the outermost paper tube. The support bars are adhesively fixed by spot-applying casein glue to the side surfaces adjacent to the paper tube. The coil P4 is wound around the coil P2 and the outermost support bars in a right-handed descending layer winding manner from top to bottom; After the winding of the coil P4 is completed, lower pads are placed on both sides of the lower leads of the coil P4 to flatten the lower end of the coil P4. A PET tape is tied around the outer circumference of the circle formed by the lower pads. The lower ends of the leads of the coil P4 and the lower ends of the leads of the coil P3 are bent into a U-shaped connection structure, and crepe paper is wound around the outer circumference of the wire at the bending position. A number of layers of support bar - paper tube are arranged on the outer circumference of the coil P4. A number of support bars are arranged on the outer circumference of the outermost paper tube. The support bars are adhesively fixed by spot-applying casein glue to the side surfaces adjacent to the paper tube. The coil P3 is wound around the coil P4 and the outermost support bars in a left-handed ascending layer winding manner from bottom to top. Lower pads are placed on both sides of the lower leads of the coil P3 to flatten the lower end of the coil P3. A PET tape is tied around the outer circumference of the circle formed by the lower pads; After the winding of the coil P3 is completed, the wires on the adjustable winding mold are wound on the wire reel. Lower pads are placed on both sides of the lower leads of the coil P2 to flatten the lower end of the coil P2. A PET tape is tied around the outer circumference of the circle formed by the lower pads. The lower ends of the leads of the coil P2 and the lower ends of the leads of the coil P1 are bent into a U-shaped connection structure, and crepe paper is wound around the outer circumference of the wire at the bending position. A number of layers of support bar - paper tube are arranged on the outer circumference of the coil P3. A number of support bars are arranged on the outer circumference of the outermost paper tube. The support bars are adhesively fixed by spot-applying casein glue to the side surfaces adjacent to the paper tube. The coil P1 is wound around the coil P3 and the outermost support bars in a left-handed ascending layer winding manner from bottom to top. Lower pads are placed on both sides of the lower leads of the coil P1 to flatten the lower end of the coil P1. A PET tape is tied around the outer circumference of the circle formed by the lower pads; After the winding of the coil P1 is completed, upper end rings are respectively placed on the tops of the coil P2, the coil P4, the coil P3 and the coil P1 to flatten the tops of the coils. The wires are bent and led out of the upper leads from the notches of the upper end rings, and crepe paper is wound around the outer circumference of the wires at the bending positions.
[0015] Preferably, according to the single-turn circumference and the number of turns of the outermost coil P1, the total length of the wire required for the coil P1 is calculated and reserved in advance.
[0016] The beneficial effects of the present invention: In traditional multi-layer coils, the innermost and outermost coils are connected by welding. This method will produce hundreds of solder joints, which is not only time-consuming and laborious, but also there is a risk of cracking at the solder joints due to coil compression or stress during long-term operation, resulting in a short-circuit risk. An inner and outer double-coil structure proposed by the present invention can save space, realize solderless winding of multi-layer coils, and greatly reduce the risk of solder joint cracking in the coil compression stage and the operation stage. A winding method of the inner and outer double-coil structure proposed by the present invention cleverly utilizes an adjustable winding mold and reasonably designs the wire winding steps, with simple manufacturing process, low cost, high winding efficiency, reducing the labor and material costs, and effectively enhancing the short-circuit resistance of the coil. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some specific embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings within the scope of protection of this application can also be obtained based on these drawings; Figure 1 is a schematic cross-sectional view of one side of the inner and outer double-coil in Embodiment 1 of the present invention; Figure 2 is a bottom view of the inner and outer double-coil in Embodiment 1 of the present invention, where 2-1 is the bottom view of the coil P4-P3, Figure 2-2 is the bottom view of the coil P2-P1; Figure 3 is an expanded schematic view of the coils P2 and P4 in Embodiment 1 of the present invention; Figure 4 is an expanded schematic view of the coils P1 and P3 in Embodiment 1 of the present invention; Figure 5 is a schematic structural view of the upper end ring in Embodiment 1 of the present invention, where 5-1 is the front view of the upper end ring and 5-2 is the top view of the upper end ring; Figure 6 is a schematic structural view of the lower spacer in Embodiment 1 of the present invention, where 6-1 is the bottom view of the position where the lower spacer is placed and 6-2 is the A-A rotational sectional view in 6-1; Figure 7 is a schematic diagram of the wire winding direction and wiring principle of the inner and outer double-coil in Embodiment 1 of the present invention; Figure 8 is a flowchart of the winding method of the inner and outer double-coil structure in Embodiment 2 of the present invention; Figure 9 is a schematic diagram of reserving the wire for the coil P1 on the adjustable winding mold in Embodiment 2 of the present invention; In the figure, 21 is a stay bar, 22 is a paper tube, 23 is crepe paper, 24 is an upper end ring, 25 is a lower cushion block, 26 is an insulating paper tube outside the iron core column, 27 is an adjustable winding mold, and 28 is a PET tape. Detailed implementation manners
[0018] The technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Embodiment 1
[0019] As Figure 1-7 shown, a double-layer coil structure inside and outside includes an outer-layer coil and an inner-layer coil sleeved at the inner central position of the outer-layer coil. The inner-layer coil includes coil P4 and coil P3. Coil P4 and coil P3 are continuously wound by six wires without interruption. The wires at the lower ends of coil P4 and coil P3 are bent into a U-shaped connection structure to realize their series connection. The wires at the upper ends of coil P4 and coil P3 are bent to lead out the upper end of the coil. The bent parts of the wires at the upper and lower ends of coil P4 and coil P3 are respectively wrapped with crepe paper 23 with heat resistance. Crepe paper 23 is used to improve the insulation strength and mechanical strength of coil P4 and coil P3. The outer-layer coil includes coil P2 and coil P1. Coil P2 and coil P1 are continuously wound by six wires without interruption. The wires at the lower ends of coil P2 and coil P1 are bent into a U-shaped connection structure to realize their series connection. The wires at the upper ends of coil P2 and coil P1 are bent to lead out the upper end of the coil. The bent parts of the wires at the upper and lower ends of coil P2 and coil P1 are respectively wrapped with crepe paper 23 with heat resistance. Crepe paper 23 is used to improve the insulation strength and mechanical strength of coil P2 and coil P1. Coil P2 and coil P4 are wound with the wire in the right-handed direction, and coil P3 and coil P1 are wound with the wire in the left-handed direction. Figure 3 、 Figure 4 reflect the different wire winding directions. The wire winding directions of the inner and outer layers are opposite, which can ensure that the magnetic flux directions of the inner and outer series-connected wires are the same and balance the electromagnetic force. In coil P2 and coil P1, and in coil P4 and coil P3, six wires respectively form six bent U-shaped connection structures at the lower end of the coil. The six U-shaped connection structures are evenly distributed along the circumference of the coil, eliminating the need for wire welding. The double-layer coil structure inside and outside improves the space utilization rate of the transformer or reactor and can wind more turns of coils in a limited space.
[0020] The outer-layer coil is sleeved on the outer circumference of the insulating paper tube 26 outside the iron core column. Coil P2 is close to the iron core column. Several vertical stay bars 21 evenly distributed in the circumferential direction are arranged between the insulating paper tube 26 outside the iron core column and coil P2. Several vertical stay bars 21 evenly distributed in the circumferential direction are arranged on the outer circumference of coil P1. A paper tube for the coil assembly process is also arranged outside the outermost stay bar 21. This part is inFigure 1 is not shown; the inner coil is sleeved at the inner center position of the outer coil. The coil P4 is close to the iron core column. A plurality of paper tubes 22 are arranged at the central position between the coil P4 and the coil P3. A plurality of paper tubes 22 are sleeved between the outer coil and the inner coil (between the coil P4 and the coil P2, and between the coil P3 and the coil P1). A plurality of vertically arranged struts 21 evenly distributed in the circumferential direction are arranged between adjacent paper tubes 22, between the paper tubes 22 and the outer coil, and between the paper tubes 22 and the inner coil. By arranging the struts 21 and the paper tubes 22 between each layer of coils, the overall heat dissipation effect and insulation margin of the coils are improved. A small amount of casein glue is dot-coated on the side of the strut 21 adjacent to the paper tube 22 for bonding and fixing. Then, after the coil, the strut 21 and the paper tube 22 are pressed against each other, they are combined into a firm coil integral structure by the tension force.
[0021] Upper end rings 24 are respectively arranged on the upper parts of the coils P2, P1, P4 and P3. The upper end rings 24 are used to flatten the upper ends of the coils. The material of the upper end rings 24 is preferably sulfate paper. The upper end rings 24 are made of sulfate pulp. The bottom of the upper end rings 24 is a spiral structure that matches the top of the coil. The upper part of the upper end rings 24 is a horizontal structure. The end of the upper end ring 24 is processed into a chamfer structure, and the chamfer structure can damage the wire. A notch is arranged on the upper end ring 24. After the multi-layer coils are wound and pressed against each other inside and outside, the upper end ring 24 is directly placed on the top of the coil, and the upper lead of the coil is led out at the notch of the upper end ring 24. The thickness of the upper end ring 24 is the same as the thickness of a single-layer coil.
[0022] A plurality of lower pads 25 evenly distributed in the circumferential direction are respectively arranged at the bottoms of the coils P2, P1, P4 and P3. The lower pads 25 are used to flatten the bottoms of the coils. The material of the lower pads 25 is preferably laminated cardboard. The top of the lower pads 25 is a slope structure that matches the bottom of the coil. The bottom of the lower pads 25 is a horizontal structure. The thickness of the lower pads 25 is the same as the thickness of a single-layer coil. The lower pads 25 are placed on both sides of the lower leads of each layer of coils, and at the same time, a whole circle of binding is carried out on the outer circumference surrounded by the lower pads 25 with a PET tape 28.
[0023] Note: Figure 1 The lower horizontal solid line in [the figure] is to indicate the series connection relationship between the coil P2 and the coil P1, and between the coil P4 and the coil P3 through the U-shaped connection structure. Figure 1 The upper horizontal solid line in [the figure] represents the upper leads, and they do not represent the actual cross-sectional structure lines. The number of wires used in parallel for winding the coil needs to be flexibly selected according to the design requirements of the transformer. Embodiment 2
[0024] As Figure 8, 9 As shown in 9 , a winding method for an inner and outer double - coil structure described in Embodiment 1 includes the following steps: First, according to the single - turn perimeter and the number of turns of the outermost coil P1, calculate and reserve in advance the total length of the wire required for coil P1.
[0025] Place a number of spacers 21 evenly on the outer periphery of the insulating paper tube 26 on the iron core column. A small amount of casein glue is applied by dotting on the side surface of the spacer 21 adjacent to the insulating paper tube 26 on the iron core column for bonding and fixing. Wind the coil P2 around the insulating paper tube 26 on the iron core column and the spacer 21 in a right - hand descending layer winding manner from top to bottom. After the coil P2 is wound, wind the remaining wires for winding the coil P1 around the adjustable winding die 27 one by one. The adjustable winding die 27 is an existing product. The "adjustable" means that the cylindrical diameter of the winding die is adjustable, and it is necessary to cooperate with the rolling of the winding machine to wind the wire onto the adjustable winding die 27.
[0026] Place spacers 21 - paper tube 22 - spacers 21 - paper tube 22 - spacers 21 from the inside to the outside in sequence on the outer periphery of the coil P2. A small amount of casein glue is applied by dotting on the side surface of the spacer 21 adjacent to the paper tube 22 for bonding and fixing. Wind the coil P4 around the coil P2 and the outermost spacer 21 in a right - hand descending layer winding manner from top to bottom.
[0027] After the coil P4 is wound, place six lower pads 25 at the lower end of the coil P4 to flatten the lower end of the coil P4. The lower pads 25 are placed on both sides of the lower leads of the coil P4. Bind a circle of PET tape 28 on the outer circumference surrounded by the six lower pads 25 to fix the lower pads 25. Bend the lower leads of the coil P4 and the lower leads of the coil P3 into a U - shaped connection structure, and wind crepe paper 23 around the wire at the bending position. Place spacers 21 - paper tube 22 - spacers 21 - paper tube 22 - spacers 21 from the inside to the outside in sequence on the outer periphery of the coil P4. A small amount of casein glue is applied by dotting on the side surface of the spacer 21 adjacent to the paper tube 22 for bonding and fixing. Wind the coil P3 around the coil P4 and the outermost spacer 21 in a left - hand ascending layer winding manner from bottom to top. Six lower pads 25 are also placed at the lower end of the coil P3 to flatten the lower end of the coil P3.
[0028] After the winding of coil P3 is completed, the wire for winding coil P1 on the adjustable winding die 27 is rewound on the pay-off reel. Six lower pads 25 are placed at the lower end of coil P2 to flatten the lower end of coil P2. The lower pads 25 are placed on both sides of the lower leads of coil P2. A PET tape 28 is tied around the outer circumference formed by the six lower pads 25 to fix the lower pads 25. The lower end of the wire of coil P2 and the lower end of the wire of coil P1 are bent into a U-shaped connection structure, and crepe paper 23 is wound around the outer circumference of the wire at the bending position. Stiffeners 21 - paper tubes 22 - stiffeners 21 - paper tubes 22 - stiffeners 21 are sequentially placed from the inside to the outside around the outer circumference of coil P3. A small amount of casein glue is applied by dotting at the side of the stiffener 21 adjacent to the paper tube 22 for bonding and fixing. Coil P1 is wound layer by layer with a left-handed ascending winding direction from the bottom up around coil P3 and the outermost stiffener 21. Six lower pads 25 are also placed at the lower end of coil P1 to flatten the lower end of coil P1.
[0029] After the winding of coil P1 is completed, upper end rings 24 are respectively placed at the tops of coil P2, coil P4, coil P3 and coil P1 to flatten the tops of the coils. The wire is bent and the upper leads are led out from the notch of the upper end ring 24. Crepe paper 23 is wound around the outer circumference of the wire at the bending position, thus completing the winding of the entire inner and outer double-coil structure.
[0030] In the embodiments of the present invention, the technical features not described in detail are all prior arts or conventional technical means, and will not be elaborated here.
[0031] Finally, it should be noted that: the above embodiments are only specific embodiments of the present invention, used to illustrate the technical solutions of the present invention, rather than limiting it. The protection scope of the present invention is not limited thereto. Those skilled in the art should understand that: any person skilled in the art within the technical scope disclosed by the present invention can modify the technical solutions recorded in the foregoing embodiments or can easily think of changes, or perform equivalent replacements on some of the technical features; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the protection scope of the present invention.
Claims
1. An internal and external double - coil structure, comprising an outer coil and an inner coil sleeved at the inner central position of the outer coil, characterized in that The inner layer coil includes coil P4 and coil P3. Coil P4 and coil P3 are continuously wound by several wires without interruption. The wires at the lower ends of coil P4 and coil P3 are bent into a U-shaped connection structure, and the wires at the upper ends of coil P4 and coil P3 are bent to lead out the upper end of the coil. The outer layer coil includes coil P2 and coil P1. Coil P2 and coil P1 are continuously wound by several wires without interruption. The wires at the lower ends of coil P2 and coil P1 are bent into a U-shaped connection structure, and the wires at the upper ends of coil P2 and coil P1 are bent to lead out the upper end of the coil. At the tops of coil P2, coil P1, coil P4 and coil P3, upper end rings for flattening the top of the coil are respectively provided, and notches are provided on the upper end rings. At the bottoms of coil P2, coil P1, coil P4 and coil P3, several lower pads evenly distributed circumferentially for flattening the bottom of the coil are respectively provided.
2. The internal and external double coil structure according to claim 1, characterized in that Coil P2 and coil P4 are wound with the wire in the right-handed direction, and coil P3 and coil P1 are wound with the wire in the left-handed direction.
3. The internal and external double coil structure according to claim 1, characterized in that The bottom of the upper end ring is a spiral structure matching the top of the coil, the upper part of the upper end ring is a horizontal structure, the end of the upper end ring is processed into a chamfer structure, and the thickness of the upper end ring is the same as the thickness of the single-layer coil.
4. A double-coil structure with inner and outer coils according to claim 3, characterized in that The material of the upper end ring is sulfate paper.
5. A double-coil structure with inner and outer coils according to claim 1, characterized in that, The top of the lower pad is a slope structure matching the bottom of the coil, the bottom of the lower pad is a horizontal structure, the thickness of the lower pad is the same as the thickness of the single-layer coil, the lower pads are placed on both sides of the lower end of the coil, and a whole circle of PET tape is tied and set on the outer circumference surrounded by the lower pads.
6. The internal and external double coil structure according to claim 5, characterized in that, The material of the lower pad is laminated cardboard.
7. A double-coil structure inside and outside as claimed in claim 1, wherein, The outer layer coil is sleeved on the outer circumference of the insulating paper tube on the iron core column. Coil P2 and coil P4 are close to the iron core column. Several struts evenly distributed circumferentially are arranged between the insulating paper tube on the iron core column and coil P2, and several struts evenly distributed circumferentially are arranged on the outer circumference of coil P1. Several paper tubes are sleeved between coil P4 and coil P2, between coil P4 and coil P3, and between coil P3 and coil P1. Several struts evenly distributed circumferentially are arranged between adjacent paper tubes and between the paper tubes and the coils. The side of the strut adjacent to the paper tube is spot-coated with casein glue.
8. A double-coil structure inside and outside according to claim 1, characterized in that, The bent part of the wire is wrapped with crepe paper.
9. The winding method of an internal and external double-coil structure according to claim 7, characterized in that, It includes the following steps: Several struts are evenly arranged on the outer circumference of the insulating paper tube on the iron core column. The side of the strut adjacent to the insulating paper tube on the iron core column is spot-coated with casein glue for bonding and fixing. Coil P2 is wound around the insulating paper tube on the iron core column and the struts from top to bottom in the right-handed direction with decreasing layers. After coil P2 is wound, the wires for winding coil P1 are respectively wound around the adjustable winding mold one by one. Several layers of strut-paper tubes are arranged on the outer circumference of coil P2. Several struts are arranged on the outer circumference of the outermost paper tube. The side of the strut adjacent to the paper tube is spot-coated with casein glue for bonding and fixing. Coil P4 is wound around coil P2 and the outermost struts from top to bottom in the right-handed direction with decreasing layers. After the winding of coil P4 is completed, lower pads are placed on both sides of the lower leads of coil P4 to flatten the lower end of coil P4. A PET tape is tied around the outer circumference formed by the lower pads. The lower ends of the leads of coil P4 and the lower ends of the leads of coil P3 are bent into a U-shaped connection structure, and crepe paper is wound around the outer circumference of the leads at the bending position. Several layers of spacer-paper tubes are arranged on the outer circumference of coil P4. Several spacers are arranged on the outer circumference of the outermost paper tube. Casein glue is applied by dotting on the side surfaces of the spacers adjacent to the paper tube for bonding and fixing. Coil P3 is wound around coil P4 and the outermost spacers in a left-handed ascending layer winding manner from bottom to top. Lower pads are placed on both sides of the lower leads of coil P3 to flatten the lower end of coil P3. A PET tape is tied around the outer circumference formed by the lower pads; After the winding of coil P3 is completed, the wire on the adjustable winding die is wound on the wire reel. Lower pads are placed on both sides of the lower leads of coil P2 to flatten the lower end of coil P2. A PET tape is tied around the outer circumference formed by the lower pads. The lower ends of the leads of coil P2 and the lower ends of the leads of coil P1 are bent into a U-shaped connection structure, and crepe paper is wound around the outer circumference of the leads at the bending position. Several layers of spacer-paper tubes are arranged on the outer circumference of coil P3. Several spacers are arranged on the outer circumference of the outermost paper tube. Casein glue is applied by dotting on the side surfaces of the spacers adjacent to the paper tube for bonding and fixing. Coil P1 is wound around coil P3 and the outermost spacers in a left-handed ascending layer winding manner from bottom to top. Lower pads are placed on both sides of the lower leads of coil P1 to flatten the lower end of coil P1. A PET tape is tied around the outer circumference formed by the lower pads; After the winding of coil P1 is completed, upper end rings are respectively placed on the tops of coils P2, P4, P3 and P1 to flatten the tops of the coils. The wire is bent and led out from the notch of the upper end ring as the upper leads, and crepe paper is wound around the outer circumference of the wire at the bending position.
10. A winding method for an internal and external double - coil structure according to claim 9, characterized in that, According to the single-turn circumference and the number of turns of the outermost coil P1, the total length of the wire required for coil P1 is calculated and reserved in advance.