A casting device and casting process for low-voltage foil winding coils of dry-type transformers.

Abstract

This invention relates to a casting device and casting process for low-voltage foil winding coils of a dry-type transformer, belonging to the field of transformer technology. It includes a base with a bottom plate on it. An inner casting mold and an outer casting mold are nested together on the bottom plate. A pressure frame is provided at the top of both the inner and outer casting molds. A pull screw is installed through the inner and outer casting molds and the bottom plate, with nuts at both ends of the pull screw to tighten the inner and outer casting molds. The outer casting mold has a pair of flanges. It also includes a feed pipe on the bottom plate with two pairs of flanges. A sealing strip is located inside the outer flange, and a sealing strip is located between the inner flange and the inner flange. A feed hole is located below the sealing strip. This invention's casting device uses the principle of communicating vessels, starting casting from the bottom of the transformer's low-voltage coil, allowing the epoxy casting material to enter the outer casting mold from the bottom, facilitating air bubble removal and ensuring casting quality. The bottom communicating opening structure facilitates demolding.

Description

Technical Field

[0001] This invention relates to a casting device and casting process for low-voltage foil winding coils of a dry-type transformer, belonging to the field of transformer technology. Background Technology

[0002] A typical dry-type transformer consists of a high-voltage coil cast in epoxy resin, a low-voltage coil without epoxy resin, and an iron core. An insulating cylinder is placed between the high-voltage and low-voltage coils to increase electrical insulation, and the coils are supported and constrained by pads. Dry-type transformers have advantages such as low maintenance workload, high operating efficiency, small size, and low noise. However, the lack of epoxy resin in the low-voltage coil limits the waterproof and moisture-proof performance and short-circuit withstand capability of dry-type transformers, especially in some special applications (such as offshore wind power, marine transformers, nuclear power transformers, and other environments with relatively harsh conditions).

[0003] Currently, the main material used for casting dry-type transformers is epoxy resin with filler. While this improves heat dissipation performance, it also leads to casting defects due to the poor fluidity of the resin. Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned problems by providing a casting device and casting process for low-voltage foil winding coils of dry-type transformers.

[0005] This invention is achieved through the following technical solution:

[0006] A casting device for low-voltage foil winding coils of a dry-type transformer includes a base, a base plate on the base, and a casting inner mold and a casting outer mold nested together on the base plate. A pressure frame is provided at the top of the casting inner mold and the casting outer mold. A pull screw is installed through the casting inner mold, the casting outer mold and the base plate. Nuts are used at both ends of the pull screw to press the casting inner mold and the casting outer mold together. A pair of flanges are provided on the casting outer mold.

[0007] It also includes a feed pipe set on the base plate, with two pairs of flanges on the feed pipe. The outer flange has a sealing strip inside, and the inner flange and flange are connected to a sealing strip. A feed hole is provided below the sealing strip.

[0008] This invention's casting device utilizes the principle of communicating vessels, starting casting from the lower part of the transformer's low-voltage coil. The epoxy casting material overflows from the bottom to the end, entering the main mold through a feed hole located below the sealing strip. This facilitates air bubble removal, ensuring casting quality. The bottom-connecting opening structure facilitates demolding, eliminating the need to manipulate the resin in the low-voltage coil. The mold is a soft mold structure, resulting in low cost.

[0009] A further improvement of the present invention is that a rubber sealing plate is provided on the bottom plate, which improves the sealing effect at the bottom of the pouring device.

[0010] A further improvement of the present invention is that the pressure frame is I-shaped and has an overflow port. Epoxy resin is injected through the feed pipe into the outer mold, and flows out through the overflow port after it is full.

[0011] A further improvement of the present invention is that the lower end of the sealing strip is provided with a protruding edge, and the feed hole is opened on the protruding edge. The feed hole at the lower end of the sealing strip connects the feed pipe and the outer mold for casting, which helps to ensure the casting effect, facilitates the control of the casting speed, and ensures the casting quality.

[0012] A further improvement of the present invention is that pressure plates are installed on the outer sides of both flange one and flange two, and sealing strip one and sealing strip two are clamped together using bolts and nuts. This ensures smooth entry of the epoxy resin into the outer mold during the epoxy resin pouring process, improving sealing performance.

[0013] A further improvement of the present invention is that the inner end of the second sealing strip is provided with a groove, and both the inner and outer ends of the first sealing strip are provided with grooves. The outer surfaces of the first and second flanges are provided with protrusions that match the grooves. The sealing strips and flanges cooperate through the grooves and protrusions, further improving the sealing performance.

[0014] The present invention also provides a casting process for a casting device for a low-voltage foil winding coil of a dry-type transformer, comprising the following steps:

[0015] S1: Assemble the inner mold, base plate, and pressure frame for casting, and install them on the winding machine shaft;

[0016] S2: Fix the glass grid on the inner mold as required by the drawing, and tie it tightly with alkali-free and wax-free glass ribbon;

[0017] S3: After welding the copper busbars according to the dimensions in the drawing, start winding. After the coil is wound, wind the external insulation on the outside according to the requirements of the drawing. Add a glass mesh to the outermost layer of the coil and bind it with alkali-free and wax-free glass ribbon. The cast low-voltage coil does not have end insulation.

[0018] S4: Remove the wound coil, along with the inner mold, base plate, and pressure frame, from the foil winding machine and proceed to the mold closing process;

[0019] S5: Stand up the wound coil and loosen the coil clamp;

[0020] S6: Connects the outer casting mold, pressure plate, and sealing strip;

[0021] S7: Connects the feed pipe, sealing strip 2, and pressure plate. The feed pipe is connected to the space between the inner mold and the outer mold through the feed hole.

[0022] S8: Pressing frame;

[0023] S9: Pre-baking process, to preheat the low-voltage coil and mold;

[0024] S10: Curing is performed according to the curing process;

[0025] S11: Demolding. Demolding is performed in the order of pouring inlet mold, pouring outer mold, and sealing strip 1.

[0026] The process steps are rationally designed. Utilizing the principle of communicating vessels, the epoxy resin is poured starting from the bottom of the transformer's low-voltage coil, overflowing from the bottom to the end and entering the main mold through a feed hole located below the sealing strip. This facilitates air bubble removal, ensuring casting quality. The bottom-connecting opening structure facilitates demolding, eliminating the need to manipulate the resin in the low-voltage coil.

[0027] A further improvement of the present invention is that, in step S2, before the coil is wound, a release agent is applied to the inner casting mold, the outer casting mold, the sealing strip, the silicone strip, and the feed tube to facilitate demolding.

[0028] Compared with the prior art, the beneficial effects of this invention are:

[0029] 1. The casting device of this invention adopts the principle of communicating vessels, starting the casting from the lower part of the transformer's low-voltage coil, allowing the epoxy casting material to overflow from the bottom to the end and enter the main mold through the feed hole located below the sealing strip. This facilitates the removal of air bubbles, ensuring casting quality. The bottom communicating opening structure facilitates demolding, eliminates the need to manipulate the resin in the low-voltage coil, and the mold is a soft mold structure, resulting in low cost.

[0030] 2. The process steps are reasonably set. Utilizing the principle of communicating vessels, the epoxy casting starts from the bottom of the transformer's low-voltage coil, allowing the epoxy casting material to overflow from the bottom to the end and enter the main mold through the feed hole located below the sealing strip. This facilitates air bubble removal, ensuring casting quality. The bottom-connecting opening structure facilitates demolding, eliminating the need to manipulate the resin in the low-voltage coil. Attached Figure Description

[0031] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a structural schematic diagram of a specific embodiment of the present invention.

[0033] Figure 2 for Figure 1 A top-view structural diagram.

[0034] Figure 3 for Figure 2 A magnified schematic diagram of the structure at point A in the middle.

[0035] Figure 4 This is a front view structural diagram of a sealing strip according to a specific embodiment of the present invention.

[0036] Figure 5 This is a side view of the sealing strip according to a specific embodiment of the present invention.

[0037] Figure 6 This is a top view of the sealing strip according to a specific embodiment of the present invention.

[0038] Figure 7 This is a schematic diagram of the main structure of the sealing strip two according to a specific embodiment of the present invention.

[0039] Figure 8 This is a side view of the sealing strip two according to a specific embodiment of the present invention.

[0040] In the diagram: 1. Base; 2. Base plate; 3. Rubber sealing plate; 4. Inner casting mold; 5. Outer casting mold; 6. Press frame; 7. Pull screw; 8. Flanged edge one; 9. ; 10. Flanged edge two; 11. Press plate; 12. Sealing strip one; 13. Overflow port; 14. Sealing strip two; 15. Raised edge; 16. Feed hole; 17. Groove; 18. Raised strip. Detailed Implementation

[0041] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0042] like Figure 1 As for Figure 8 The present invention relates to a casting device for a low-voltage foil winding coil of a dry-type transformer, comprising a base 1, a base plate 2 and a rubber sealing plate 3 on the base 1, an inner casting mold 4 and an outer casting mold 5 nested together on the rubber sealing plate 3, an I-shaped pressure frame 6 at the top of the inner casting mold 4 and the outer casting mold 5, and an overflow port 13 on the pressure frame 6, a pull screw 7 installed through the inner casting mold 4, the outer casting mold 5 and the base plate 2, the two ends of the pull screw 7 being tightened with nuts to the inner casting mold 4 and the outer casting mold 5, and a pair of flanges 8 on the outer casting mold 5;

[0043] It also includes a feed pipe 9 set on the base plate 2. The feed pipe 9 is provided with two pairs of flanges 10. The outer flange 10 is provided with a sealing strip 14. The inner flange 10 and the flange 8 are provided with a sealing strip 12. The lower part of the sealing strip 12 is provided with a feed hole 16.

[0044] Among them, the lower end of the sealing strip 12 is provided with a protruding edge 15, and the feed hole 16 is opened on the protruding edge 15.

[0045] Among them, the outer sides of flange 1 8 and flange 2 10 are both equipped with pressure plates 11, and the sealing strip 1 12 and sealing strip 2 14 are clamped with bolts and nuts respectively.

[0046] Among them, the inner end of the sealing strip 14 is provided with a groove 17, the inner and outer ends of the sealing strip 12 are both provided with grooves 17, and the outer surfaces of the flange 18 and flange 2 10 are provided with protrusions that match the grooves 17.

[0047] The present invention also provides a casting process for a casting device for a low-voltage foil winding coil of a dry-type transformer, comprising the following steps:

[0048] S1: Assemble the inner mold 4, base plate 2, and pressure frame 6, and install them on the winding machine shaft;

[0049] S2: Fix the glass grid on the inner mold 4 according to the drawing requirements, and tie it tightly with alkali-free and wax-free glass ribbon;

[0050] S3: After welding the copper busbars according to the dimensions in the drawing, start winding. After the coil is wound, wind the external insulation on the outside according to the requirements of the drawing. Add a glass mesh to the outermost layer of the coil and bind it with alkali-free and wax-free glass ribbon. The cast low-voltage coil does not have end insulation.

[0051] S4: Remove the wound coil, along with the inner casting mold 4, the base plate 2, and the pressure frame 6, from the foil winding machine and proceed to the mold closing process.

[0052] S5: Stand up the wound coil and loosen the coil clamp 6;

[0053] S6: Connects the outer casting mold 5, pressure plate 6, and sealing strip 12;

[0054] S7: Connects the feed pipe 9, sealing strip 14 and pressure plate 11. The feed pipe 9 is connected to the space between the inner mold 4 and the outer mold 5 through the feed hole 16.

[0055] S8: Pressing frame 6;

[0056] S9: Pre-baking process, to preheat the low-voltage coil and mold;

[0057] S10: Curing is performed according to the curing process;

[0058] S11: Demolding. Demolding is performed in the following order: pouring inlet mold, pouring outer mold 5, and sealing strip 12.

[0059] In step S2, before the coil is wound, a release agent is applied to the inner casting mold 4, the outer casting mold 5, the sealing strip, the silicone strip, and the feed pipe 9.

[0060] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0061] The terms "upper," "lower," "outer," "inner," etc., used in the specification, claims, and accompanying drawings of this invention are used to distinguish relative positional relationships and are not necessarily qualitative. It should be understood that such data can be interchanged where appropriate so that embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.

[0062] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A casting device for low-voltage foil winding coils of a dry-type transformer, characterized in that, Includes a base (1), a base plate (2) on the base (1), a casting inner mold (4) and a casting outer mold (5) nested together on the base plate (2), a pressure frame (6) at the top of the casting inner mold (4) and the casting outer mold (5), a pull rod (7) installed through the casting inner mold (4), the casting outer mold (5) and the base plate (2), the two ends of the pull rod (7) are tightened with nuts to the casting inner mold (4) and the casting outer mold (5), and a pair of flanges (8) are provided on the casting outer mold (5); It also includes a feed pipe (9) set on the base plate (2), with two pairs of flanges (10) on the feed pipe (9), a sealing strip (14) inside the outer flange (10), and a sealing strip (12) between the inner flange (10) and the flange (8), with a feed hole (16) at the bottom of the sealing strip (12). The lower end of the sealing strip (12) is provided with a protruding edge (15), and the feed hole (16) is opened on the protruding edge (15); the feed pipe (9) is connected to the space between the inner mold (4) and the outer mold (5) through the feed hole (16); Pressure plates (11) are installed on the outer sides of the first flange (8) and the second flange (10), and the first sealing strip (12) and the second sealing strip (14) are clamped with bolts and nuts respectively; A rubber sealing plate (3) is provided on the base plate (2); The inner end of the sealing strip 2 (14) is provided with a groove (17), and both the inner and outer ends of the sealing strip 1 (12) are provided with grooves (17). The outer surfaces of the flange 1 (8) and flange 2 (10) are provided with protrusions that match the grooves (17).

2. The casting device for low-voltage foil winding coils of a dry-type transformer according to claim 1, characterized in that, The pressure frame (6) is I-shaped and has an overflow port (13) on it.

3. A casting process for the casting device for the low-voltage foil winding coil of a dry-type transformer as described in claim 1 or 2, characterized in that, Includes the following steps: S1: Assemble the inner mold (4), base plate (2), and pressure frame (6) and install them on the winding machine shaft; S2: Fix the glass grid on the inner mold (4) according to the drawing requirements, and tie it tightly with alkali-free and wax-free glass ribbon; S3: After welding the copper busbars according to the dimensions in the drawing, start winding. After the coil is wound, wind the external insulation on the outside according to the requirements of the drawing. Add a glass mesh to the outermost layer of the coil and bind it with alkali-free and wax-free glass ribbon. The cast low-voltage coil does not have end insulation. S4: Remove the wound coil, along with the casting inner mold (4), base plate (2), and pressure frame (6) from the foil winding machine and proceed to the mold closing process; S5: Stand up the wound coil and loosen the coil clamp (6). S6: Connect the outer casting mold (5), pressure plate (6) and sealing strip (12); S7: Connect the feed pipe (9), the sealing strip 2 (14) and the pressure plate (11). The feed pipe (9) is connected to the space between the inner mold (4) and the outer mold (5) through the feed hole (16). S8: Press the clamping frame (6); S9: Pre-baking process, which preheats the low-voltage coil and the mold; S10: Curing is performed according to the curing process; S11: Demolding. Demolding is performed in the order of pouring inlet mold, pouring outer mold (5), and sealing strip (12).

4. The casting process of the casting device for low-voltage foil winding coils of a dry-type transformer according to claim 3, characterized in that, In step S2, before the coil is wound, a release agent is applied to the inner casting mold (4), the outer casting mold (5), the sealing strip, the silicone strip, and the feed tube (9).

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