A gas duct rod group structure for transformer casting and a mounting method thereof

Abstract

The application relates to a transformer pouring air duct rod group structure and a mounting method, which comprises an air duct rod group and a flexible clamp, wherein the air duct rod group comprises a plurality of round rods arranged in a line and wrapped by a film, the round rods are internally provided with reinforcing metal wires, and the outer side of the film is coated with oil; the air duct rod group is provided with the flexible clamp at the end, and the flexible clamp comprises hollow sections, spherical balls, metal ropes and locking assemblies, the hollow sections and the spherical balls are alternately arranged and connected in series through the metal ropes, the metal ropes are respectively fixed on the locking assemblies on the corresponding sides, and the locking assemblies on the same side of the two flexible clamps are connected through a connecting assembly. The air duct rod group with different lengths and radii can be formed according to the needs, the service life of the round rods in the air duct rod group is improved, the problem that resin sharp ends appear on the inner walls of long holes of the air duct is avoided, and the air duct rod group can be fixed firmly during installation.

Description

Technical Field

[0001] This invention relates to the field of transformers, and more specifically to a structure and installation method for a gas duct bar assembly used in transformer casting. Background Technology

[0002] In the winding process of traditional dry-type transformer coils, air passage rods or plates are used in conjunction with casting molds to form the coil air passages. For example, in patent CN216054269U, an outer mold, inner mold, upper end plate, and lower end plate are used in conjunction with a fixed air passage rod for casting. After casting, the air passage rod is removed to form the air passage structure of the coil. However, the air passage structure formed by this patent includes multiple air passage holes arranged along the circumference of the coil, and the cross-section of the air passage holes is approximately rectangular. Similarly, the air passage structure in patent CN210628075U also includes multiple air passage holes arranged along the circumference of the coil, and its cross-section is also approximately rectangular.

[0003] With technological advancements, the dry-type transformer industry has seen the emergence of arc-shaped elongated air duct structures, which increase the heat dissipation space of the air duct. Existing technologies typically use combined, spliced ​​air duct rods or plates to create these elongated air ducts. For example, patent CN104157444A discloses a transformer air duct structure that utilizes a group of air duct rods with a similar square cross-section arranged side-by-side to form arc-shaped elongated air ducts. However, this combined, spliced ​​air duct rod assembly has the following drawbacks:

[0004] First, its materials are only polyoxymethylene and modified resin, and it can only be used about 20 times in the curing environment of the casting coil, and it is prone to aging and cracking.

[0005] Second, these air duct rods or air duct plates are usually approximately square or rectangular in cross-section. Due to the rounded corners of the air duct rods at the joints, there is a problem that the resin tips cannot be eliminated after the coil is cast and cured. In dry-type transformer products with voltage levels of 10kV and above, the tips of the insulation material will cause uneven electric field distribution, and charges are more likely to accumulate at the tips, forming a stronger electric field than other parts. When the local electric field strength exceeds the withstand strength of the insulation material, it will trigger partial discharge. This partial discharge will generate heat and active substances, and gradually erode the insulation material, causing the insulation performance to decline, and then problems such as short circuits and leakage will occur.

[0006] Another existing technology involves directly using an arc-shaped air duct plate for casting. For example, patent CN205984548U discloses a tile-type air duct, which includes an upper limit position of the air duct plate, a lower limit position of the air duct plate, a mold base, an air duct plate, an inner mold, an outer mold, and other structures. The air duct plate in this patent includes both arc-shaped and straight air duct plates. However, the arc-shaped air duct plate is a fixed structure, and its length and curvature cannot be flexibly adjusted according to actual conditions. In addition, the arc-shaped air duct plate is made of iron material, and its processing requires maintaining high pressing precision to meet the curvature requirements of the long holes in the air duct. Summary of the Invention

[0007] The purpose of this invention is to provide a structure and installation method for a gas duct rod assembly for transformer casting. It can form gas duct rod assemblies of different lengths and curvatures as needed, while improving the service life of the round rods in the gas duct rod assembly and avoiding the problem of resin tip formation on the inner wall of the long holes in the gas duct. It can also ensure that the gas duct rod assembly is firmly fixed during installation.

[0008] The objective of this invention is achieved through the following technical solution:

[0009] A structure for a transformer casting air duct bar assembly includes an air duct bar assembly and a flexible clamp. The air duct bar assembly comprises multiple round bars arranged in a line and wrapped with a thin film. The round bars have reinforcing metal wires inside, and the outer side of the thin film is coated with oil. The air duct bar assembly has a flexible clamp at its end, and the flexible clamp includes a hollow joint, a sphere, a metal rope, and a locking assembly. The hollow joint and the sphere are staggered and connected in series by the metal rope. The two ends of the metal rope are respectively fixed to the locking assembly on the corresponding side. The locking assemblies of two flexible clamps located on the same side are connected by a connecting assembly.

[0010] The locking assembly of the flexible clamp includes a locking bolt and a locking nut, wherein the locking nut is sleeved on the locking bolt, and the front end of the locking bolt is inserted into an adjacent hollow section and fixedly connected to the metal rope.

[0011] The locking bolt has a binding ring at its front end, and the end of the metal rope is bound to the binding ring.

[0012] The connecting assembly includes a connecting bolt and a connecting nut, wherein the connecting bolt passes sequentially through a locking bolt located on the same side of the two flexible clamps and is then threadedly connected to the connecting nut.

[0013] The upper end of the airway rod assembly is fixed by an upper end plate, and the lower end is fixed by a lower end plate.

[0014] The upper end plate is provided with an arc-shaped hole for inserting the upper end of the air supply rod assembly.

[0015] The lower end plate is provided with an arc-shaped hole for inserting the lower end of the air supply rod assembly.

[0016] After the film wraps around each round bar, a binding guide wire is provided on the outer side of the middle part of the film.

[0017] An installation method for the air duct rod assembly structure for transformer casting includes the following steps:

[0018] Step 1: Lay a thin film of appropriate width and apply oil to both sides according to the arc length of the airway orifice;

[0019] Step 2: Select a suitable diameter and number of round bars, and arrange each round bar in a row on one side of the film, wherein the overall length of each round bar reaches the design length of the long hole of the air passage on the coil;

[0020] Step 3: Fold the other side of the film over and cover each round rod so that each round rod is completely sealed inside the film, thereby forming a complete airway rod assembly;

[0021] Step 4: Place the airway rod assembly in the casting mold and position it at the airway elongated hole of the coil. Then, clamp and fix both ends of the airway rod assembly with flexible clamps.

[0022] Step 5: After the airway rod assembly is placed in the casting mold, use the upper end plate to fix the upper end of the airway rod assembly and use the lower end plate to fix the lower end of the airway rod assembly.

[0023] In step three, after the film wraps around each round bar, the guide wire is wrapped around and bound to the outer side of the middle part of the film.

[0024] The advantages and positive effects of this invention are as follows:

[0025] 1. The present invention can use round bars of appropriate diameter and quantity according to actual needs, and form airway bar groups of different lengths by wrapping them with a thin film. At the same time, the airway bar groups of the present invention can be freely bent according to the curvature of the airway orifice, making them more flexible in use.

[0026] 2. Each round bar in this invention has multiple reinforcing metal wires inside to improve its strength, which can increase the service life of the round bar.

[0027] 3. The present invention utilizes a thin film to wrap each round rod, thereby forming a complete and smooth curved surface on the inner wall of the elongated air passage after casting, thus avoiding the problem of resin tip formation.

[0028] 4. The present invention utilizes flexible clamps to assist in fixing both ends of the airway rod assembly. The flexible clamps can ensure that the film of the airway rod assembly tightly wraps around each round rod, ensuring that the film is securely fixed. At the same time, they can also flexibly bend the airway rod assembly to form the required arc, which facilitates installation. Attached Figure Description

[0029] Figure 1 This is a schematic diagram illustrating the usage state of the present invention.

[0030] Figure 2 for Figure 1 Schematic diagram of the structure of the middle airway rod assembly and the airway elongated orifice.

[0031] Figure 3 for Figure 2 Schematic diagram of the end structure of the middle airway rod assembly.

[0032] Figure 4 for Figure 3 Front view of the end of the middle airway rod assembly.

[0033] Figure 5 for Figure 1 Schematic diagram of the structure of the flexible fixture.

[0034] Figure 6 This is a schematic diagram of an airway rod structure in the prior art.

[0035] Among them, 1 is a round bar, 101 is a reinforcing metal wire, 2 is a thin film, 3 is an airway elongated hole, 4 is an airway bar, 401 is a rounded corner, 5 is a flexible clamp, 501 is a hollow section, 502 is a sphere, 503 is a locking nut, 504 is a locking bolt, 505 is a connecting bolt, and 506 is a connecting nut. Detailed Implementation

[0036] The invention will now be described in further detail with reference to the accompanying drawings.

[0037] like Figures 1-5 As shown, the present invention includes an airway rod assembly and a flexible clamp 5, wherein, as Figures 2-4 As shown, the airway rod assembly includes multiple round rods 1 arranged in a line and wrapped by a film 2. Each round rod 1 has a reinforcing metal wire 101 inside, and the film 2 is coated with oil on its outer surface. Figure 1 and Figure 5 As shown, the end of the airway rod assembly is provided with a flexible clamp 5, and the flexible clamp 5 includes a hollow section 501, a sphere 502, a metal rope, and a locking assembly. The hollow section 501 and the sphere 502 are staggered and connected in series by the metal rope. Both the hollow section 501 and the sphere 502 have through holes for the metal rope to pass through. The two ends of the metal rope are respectively fixed to the locking assemblies on the corresponding sides. The locking assemblies of the two flexible clamps 5 located on the same side are connected by a connecting assembly, thereby achieving the purpose of clamping the end of the airway rod assembly. Both the hollow section 501 and the sphere 502 are made of metal.

[0038] In this embodiment, the round rod 1 can be made of insulating materials such as polyoxymethylene, polytetrafluoroethylene, and polyesterimide, the reinforcing metal wire 101 is a steel wire, the film 2 is a polyester film, and the outer side of the film 2 is coated with silicone oil.

[0039] like Figure 1 and Figure 5 As shown, in this embodiment, the locking assembly of the flexible clamp 5 includes a locking bolt 504 and a locking nut 503, wherein the locking nut 503 is sleeved on the locking bolt 504, and the front end of the locking bolt 504 is inserted into the adjacent hollow section 501 and fixedly connected to the metal rope. When using this invention, the locking bolts 504 in the locking assemblies on both sides are respectively inserted into the corresponding adjacent hollow sections 501. Then, the operator screws the locking nuts 503 on both sides and moves them along the locking bolts 504 to clamp each hollow section 501 and each ball 502, thereby achieving the locking of the overall length and position of each hollow section 501 and each ball 502.

[0040] In this embodiment, the metal rope can be made of steel wire rope, and its end can be fixed to the front end of the locking bolt 504 by welding. To further improve the flexibility of the invention, in another embodiment, a binding ring can be welded to the front end of the locking bolt 504. The end of the metal rope can pass through and be bound to the binding ring. This allows the invention to easily replace metal ropes of different lengths according to actual needs, and to form flexible clamps 5 of different lengths by connecting different numbers of hollow sections 501 and spheres 502 in series, thereby meeting the auxiliary fixing needs of airway rod assemblies of more length specifications.

[0041] like Figure 1 and Figure 5 As shown, in this embodiment, the connecting assembly includes a connecting bolt 505 and a connecting nut 506. The connecting bolt 505 passes through a locking bolt 504 located on the same side of the two flexible clamps 5 and is threadedly connected to the connecting nut 506. Furthermore, by screwing the connecting nut 506 to adjust its position on the connecting bolt 505, the present invention can also flexibly fine-tune the clamping force of the two flexible clamps 5 on the end of the airway rod assembly.

[0042] During casting, the upper end of the airway rod assembly is fixed by an upper end plate, and the lower end is fixed by a lower end plate. The upper end plate has an arc-shaped hole for inserting and fixing the upper end of the airway rod assembly, and the lower end plate has an arc-shaped hole for inserting and fixing the lower end of the airway rod assembly. Since both ends of the airway rod assembly are clamped and fixed by corresponding flexible clamps 5, the film 2 will not spread out and fail to tightly wrap the round rod 1 when the upper or lower end plate is inserted. Both the upper and lower end plates are known technologies in the art. For example, the upper and lower end plate structure in patent CN216054269U (which uses an arc-shaped hole instead of a conventional airway rod hole) can be used, or the upper and lower limit plate structure of the airway can be used in patent CN205984548U.

[0043] Furthermore, the airway rod assembly can be first wrapped with a binding guide wire around the outer side of the middle of the membrane 2 to ensure that the middle of the membrane tightly wraps around each round rod 1, for example, when the axial length of the airway rod assembly is relatively long. Then, the airway rod assembly is inserted between the inner mold and the outer mold. This can further ensure that the entire membrane 2 can completely and tightly wrap around each round rod 1, and the membrane 2 will not partially unravel during installation. In this embodiment, the binding guide wire can be a copper guide wire.

[0044] The working principle of this invention is as follows:

[0045] The installation of this invention includes the following steps:

[0046] Step 1: Lay a film 2 of appropriate width and coated with oil on both sides according to the arc length of the airway orifice 3. In this embodiment, the width of the film 2 is 2.5 times the arc length of the airway orifice 3, and the length of the film 2 is greater than the height of the coil, so as to ensure that the upper and lower ends of the film 2 can be fixed by the upper and lower end plates.

[0047] In this embodiment, the film 2 is made of polyester film because it has good flexibility and insulation properties. At the same time, the two sides of the film 2 are coated with silicone oil to facilitate subsequent operations and final removal.

[0048] Step 2: Select a suitable diameter and number of round rods 1, and arrange each round rod 1 in a row on one side of the film 2. During the arrangement process, ensure that the adjacent round rods 1 are in close contact, so that the whole group of round rods 1 are arranged tightly and neatly on the film 2 until the designed length of the coil air passage 3 is reached.

[0049] Step 3: Fold the unused side of the film 2 over each of the round rods 1. When folding, ensure that the film 2 completely and tightly wraps around each of the parallel round rods 1, so that each round rod 1 is completely sealed inside the film 2, thus forming a complete air channel rod assembly. Additionally, during the wrapping process, smooth the film 2 to avoid wrinkles or air bubbles, which could affect subsequent coil winding and casting / curing processes.

[0050] In this step, after the membrane 2 wraps around each round rod 1, a guide wire can be wrapped around the outer side of the middle part of the membrane 2 as needed (for example, when the axial length of the airway rod group is relatively long) to ensure that the middle part of the membrane tightly wraps around each round rod 1, thereby ensuring that the membrane 2 will not come apart locally during subsequent installation.

[0051] Step 4: Place the air channel rod assembly in the casting mold (between the inner mold and the outer mold) and position it at the air channel long hole 3 of the coil. Then, clamp and fix both ends of the air channel rod assembly with flexible clamps 5.

[0052] Among them, such as Figure 2As shown, since multiple air passage holes 3 are usually formed during casting, if the air passage module is inserted between the inner and outer molds, it is necessary for the operator to hold the end of the air passage module by hand to prevent the film 2 from spreading. This not only requires a large number of people and is time-consuming and labor-intensive, but also easily leads to the film 2 spreading due to the operator's weak grip, especially when the end of the air passage module is inserted into the arc-shaped hole on the corresponding side end plate. The present invention uses a flexible clamp 5 to fix the end of the air passage module, which can ensure that the end of the air passage module is firmly fixed, and also facilitates the subsequent insertion of the end of the air passage module into the arc-shaped hole on the corresponding end plate. Furthermore, the staggered and connected structure of the hollow section 501 and the sphere 502 of the flexible clamp 5 also facilitates the flexible adjustment of the curvature with the air passage rod assembly. The assembly and disassembly of the flexible clamp 5 are also very convenient.

[0053] Step 5: After the air channel rod assembly is placed between the inner and outer molds, the upper end of the air channel rod assembly is fixed with the upper end plate, and the lower end of the air channel rod assembly is fixed with the lower end plate, thus completing the installation and fixing of the air channel rod assembly. Then, subsequent coil winding, casting and other processes can be carried out.

[0054] And such Figure 1 As shown, after the coil completes the resin casting and curing process, the air channel rod assembly (including the film 2 and each round rod 1) needs to be removed from the cast coil. At this time, because the polyester film of this invention is coated with silicone oil on both sides, the adhesion between it and the cured resin is small, so it is easy to remove the air channel rod assembly. After removal, an elongated air channel hole 3 that meets the design requirements is formed inside the coil.

[0055] Compared with the prior art, the present invention can firstly use round rods 1 of appropriate diameter and number according to actual needs, and wrap them with film 2 to form airway rod groups of different lengths. At the same time, the airway rod groups of the present invention can be freely bent according to the curvature of the airway long hole 3, so it is more flexible in use.

[0056] Secondly, each of the round bars 1 in this invention is provided with multiple reinforcing metal wires 101 to improve strength, which can increase the service life of the round bars 1. Compared with the prior art, the air channel bar 4 is used about 20 times in the curing environment temperature of the casting coil, the round bars 1 of this invention can be used about 40 times.

[0057] Again Figure 6 As shown, the airway rod 4 in the prior art is usually an approximately square or rectangular structure with rounded corners 401. However, for assembled airway rod groups, the presence of two adjacent rounded corners 401 on the splicing side of two adjacent airway rods 4 results in resin sharp points between adjacent rounded corners 401 after casting, which cannot be eliminated. This leads to uneven electric field distribution, causing problems such as partial discharge. Figures 1-6As shown, the present invention utilizes a thin film 2 to wrap each round rod 1, thereby forming a complete and smooth curved surface on the inner wall of the elongated air passage 3 after casting, thus avoiding the aforementioned problem of resin tip.

[0058] Finally, the present invention uses a flexible clamp 5 to strengthen and fix both ends of the airway rod assembly. On the one hand, it can ensure that the film 2 of the airway rod assembly can tightly wrap each round rod 1 and ensure that the thin mold 2 is firmly fixed. On the other hand, the flexible clamp 5 can flexibly bend the airway rod assembly to form the required arc, which is convenient for installation.

[0059] In this embodiment, the manufacturing process of the round rod 1 is as follows:

[0060] Step 1: Melting and plasticizing the polyoxymethylene resin granules. Specifically, the mixed raw materials are added to the hopper of an extruder, and the raw materials are conveyed forward by the rotating screw. The temperature in the heating section of the extruder is controlled at 160-200℃, and the raw materials are gradually heated and melted to form a uniform melt. The extruder is a commercially available product.

[0061] Step Two: The end of the steel wire coil (i.e., reinforcing metal wire 101) of the corresponding specification is placed inside the extrusion die. After the wire end passes through the extrusion die, it is clamped by a moving jaw to achieve uniform traction and movement. Then, the molten polyoxymethylene is pushed into the extrusion die (the die cavity is circular, which determines the diameter of the rod), and a cylindrical billet is continuously extruded through the die opening of the extrusion die. At the same time, the wire end is driven by the moving jaw to move in coordination with the billet extrusion process, so that the steel wire is placed in the cylindrical billet along with the billet. The moving jaw, extrusion die, etc. are all commercially available products.

[0062] Step 3: The extruded hot cylindrical billet enters a cooling sleeve and is rapidly cooled by cold air inside the sleeve, causing the billet to solidify and form a rod. The cooling sleeve is a commercially available product.

[0063] Step 4: After cooling, the bar stock is pulled at a constant speed by a traction machine, and the traction speed is matched with the extrusion speed of the extrusion die to ensure that the bar stock is not stretched or piled up. Finally, the bar stock is cut into individual bars by a cutting device according to a set length (e.g., 1 meter, 2 meters, etc.). Both the traction machine and the cutting device are commercially available products.

[0064] The circular bar 1 is manufactured using techniques known in the art.

Claims

1. A structure for a gas duct rod assembly used in transformer casting, characterized in that: The device includes an airway rod assembly and a flexible clamp (5). The airway rod assembly includes multiple round rods (1) arranged in a line and wrapped by a film (2). The round rods (1) are provided with reinforcing metal wires (101) inside, and the film (2) is coated with oil on the outside. The airway rod assembly is provided with a flexible clamp (5) at its end. The flexible clamp (5) includes a hollow section (501), a sphere (502), a metal rope, and a locking assembly. The hollow section (501) and the sphere (502) are staggered and connected in series by the metal rope. The two ends of the metal rope are respectively fixed to the locking assembly on the corresponding side. The locking assemblies of the two flexible clamps (5) on the same side are connected by a connecting assembly.

2. The air duct bar assembly structure for transformer casting according to claim 1, characterized in that: The locking assembly of the flexible clamp (5) includes a locking bolt (504) and a locking nut (503), wherein the locking nut (503) is sleeved on the locking bolt (504), and the front end of the locking bolt (504) is inserted into an adjacent hollow section (501) and fixedly connected to the metal rope.

3. The air duct bar assembly structure for transformer casting according to claim 2, characterized in that: The locking bolt (504) has a binding ring at its front end, and the end of the metal rope is bound to the binding ring.

4. The air duct bar assembly structure for transformer casting according to claim 1, characterized in that: The connecting assembly includes a connecting bolt (505) and a connecting nut (506), wherein the connecting bolt (505) passes sequentially through a locking bolt (504) located on the same side of the two flexible clamps (5) and is then threadedly connected to the connecting nut (506).

5. The air duct bar assembly structure for transformer casting according to claim 1, characterized in that: The upper end of the airway rod assembly is fixed by an upper end plate, and the lower end is fixed by a lower end plate.

6. The air duct bar assembly structure for transformer casting according to claim 5, characterized in that: The upper end plate is provided with an arc-shaped hole for inserting the upper end of the air supply rod assembly.

7. The air duct bar assembly structure for transformer casting according to claim 5, characterized in that: The lower end plate is provided with an arc-shaped hole for inserting the lower end of the air supply rod assembly.

8. The air duct bar assembly structure for transformer casting according to claim 1, characterized in that: After the film (2) wraps around each round rod (1), a binding guide wire is provided on the outer side of the middle part of the film (2).

9. An installation method for a transformer casting air duct bar assembly structure according to claim 5, characterized in that: Includes the following steps: Step 1: Lay a film (2) of appropriate width and coated with oil on both sides according to the arc length of the airway long hole (3); Step 2: Select a suitable diameter and number of round rods (1), and arrange each round rod (1) in parallel on one side of the film (2), wherein the overall length of each round rod (1) reaches the design length of the air passage hole (3) on the coil; Step 3: Fold the empty side of the film (2) over and cover each round rod (1) so that each round rod (1) is completely sealed inside the film (2), thereby forming a complete airway rod group; Step 4: Place the airway rod assembly in the casting mold and position it at the airway long hole (3) of the coil. Then, clamp and fix both ends of the airway rod assembly with flexible clamps (5). Step 5: After the airway rod assembly is placed in the casting mold, use the upper end plate to fix the upper end of the airway rod assembly and use the lower end plate to fix the lower end of the airway rod assembly.

10. The installation method of the air duct rod assembly structure for transformer casting according to claim 9, characterized in that: In step three, after the film (2) wraps around each round rod (1), the guide wire is wrapped around the outer side of the middle part of the film (2).

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