Large transformer box cover structure and welding method thereof

Abstract

The application discloses a large transformer cover structure and a welding method thereof, and relates to the technical field of transformer oil tanks. The large transformer cover structure comprises a cover body, a supporting platform and C-shaped clamps. The cover body is in a rectangular plate structure and is arranged on the supporting platform. Two wood blocks are arranged on the supporting platform in the longitudinal direction. The lower surface of the cover body is attached to the upper surface of the wood blocks. A plurality of C-shaped clamps are respectively arranged between the two end edges of the cover body and the supporting platform. Through the synergistic effect of the arched reinforcing iron and the rectangular reinforcing iron, the cover body is formed into a micro-arch structure. The effect of no gas accumulation inside and no water accumulation outside can be achieved without increasing the thickness of the steel plate. The problem of cover deformation and water accumulation is fundamentally solved.

Description

Technical Field

[0001] This invention relates to the field of transformer tank manufacturing technology, specifically to a large transformer tank cover structure and its welding method. Background Technology

[0002] Large power transformers are core equipment in power grid systems. Their tanks are huge, and the corresponding tank cover steel plates are also extremely large. Due to the large area of ​​the steel plates, the tank cover is prone to deformation during manufacturing and long-term operation, resulting in dents on the surface and the accumulation of rainwater. This not only seriously affects the appearance of the transformer, but long-term water accumulation may also lead to corrosion, thereby affecting the normal operation and service life of the transformer.

[0003] To address the aforementioned issue of water accumulation due to lid deformation, the following two solutions are typically employed in existing technologies: The first approach uses a trapezoidal or arched roof structure. This structure guides rainwater away by creating a slight inclination on the roof surface. However, this approach has significant drawbacks in practical application: due to the cumulative errors that can easily occur during the manufacturing process of the inclined mounting surface, the bushing installation suffers from large deviations, making it difficult to guarantee the bushing's verticality. This greatly increases the difficulty of connecting the bushing to external power grid equipment and also poses significant inconvenience and safety hazards for operators performing installation and maintenance work above the roof.

[0004] The second option is to adopt a flat-top structure and significantly increase the thickness of the steel plate of the tank cover to resist deformation and prevent water accumulation. Although this option can keep the installation surface flat, its disadvantages are also prominent: increasing the thickness of the steel plate directly leads to a significant increase in the overall weight of the transformer, which not only increases material costs, but also puts higher requirements on the transportation, hoisting and foundation bearing capacity of the transformer, resulting in a waste of resources.

[0005] In summary, existing large transformer tank cover structures are insufficient to simultaneously address issues of deformation prevention, water accumulation prevention, ease of installation, and cost-effectiveness. Therefore, there is an urgent need in this field for a large transformer tank cover structure and its welding method to solve the aforementioned technical problems. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a large transformer tank cover structure and its welding method. Without increasing the thickness of the tank cover steel plate, it solves the problem that large transformer tank covers are prone to deformation and denting during manufacturing and operation, leading to surface water accumulation and corrosion. It achieves the technical effects of preventing tank cover deformation and water accumulation, ensuring the flatness of the installation surface and the verticality of the bushing installation.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a large transformer tank cover structure, comprising a tank cover body, a support platform, and C-shaped clamps. The tank cover body is a rectangular plate structure and is disposed on the support platform. Two wooden blocks are arranged longitudinally on the support platform. The lower surface of the tank cover body is attached to the upper surface of the wooden blocks. Several C-shaped clamps are respectively connected between the two ends of the tank cover body and the support platform to fix the tank cover body on the support platform. The direction in which the tank cover body extends along its length is longitudinal, and the direction in which it extends along its width is transverse. The longitudinal direction and the transverse direction are perpendicular to each other. The upper surface of the tank cover body is welded with an arched reinforcing iron arranged along the transverse direction and several rectangular reinforcing irons arranged along the longitudinal direction. The arched reinforcing iron and the rectangular reinforcing irons make the tank cover body form a slightly arched structure in the transverse direction, with the middle being higher than the two sides.

[0008] Preferably, the upper surface of the arched reinforcing iron is a straight plane, the lower surface of the arched reinforcing iron is a welding surface, the welding surface has a height difference of 5mm from the center point to the end point, and the arc of the arched reinforcing iron satisfies the formula: R=(L / 2)²÷10, where L is the length of the arched reinforcing iron and R is the radius of the arc, both in mm.

[0009] Preferably, a number of flanges are welded and fixed on the cover body, including a switch flange, a high-pressure bushing flange, a manhole flange, a grounding bushing flange, and a pressure relief valve flange.

[0010] A welding method for a large transformer tank cover structure, applied to the large transformer tank cover structure according to any one of claims 1-3, the welding method comprising the following steps: S1. Place two wooden blocks longitudinally on the support platform, place the box cover body on the wooden blocks, set several C-shaped clamps at both ends of the box cover body, apply downward pressure to both ends of the box cover body through the C-shaped clamps, and press the box cover body into an arch shape. S2. Spot weld the flange to the box cover body, spot weld the arched reinforcing iron along the transverse direction, spot weld the rectangular reinforcing iron along the longitudinal direction, so that the box cover forms a height that is slightly higher in the middle than on both sides. S3. Fully weld all flanges and reinforcing irons. After the welds have cooled, remove the C-shaped clamps. The arched reinforcing irons are preferred to prevent the box cover body from springing back and deforming.

[0011] Preferably, the C-shaped clamp includes a C-shaped frame and an upper screw and a lower screw respectively disposed on the C-shaped frame. The C-shaped frame spans between the edge of the box cover body and the support platform. The lower screw abuts against the support platform to fix the C-shaped clamp to the support platform. The upper screw abuts against the upper surface of the box cover body, and pressure is applied to the box cover body by tightening the upper screw. Beneficial effects

[0012] This invention provides a large transformer tank cover structure and its welding method, which has the following beneficial effects: 1. By combining the arched and rectangular reinforcing iron, the lid body forms a micro-arched structure, achieving the effect of preventing air accumulation inside and water accumulation outside without increasing the thickness of the steel plate, thus fundamentally solving the problem of lid deformation and water accumulation.

[0013] 2. The present invention adopts a flat-top micro-arch structure, which avoids the manufacturing errors caused by the inclined installation surface of traditional trapezoidal or arched tops, effectively ensures the verticality of the installation of components such as bushings, reduces the difficulty of connecting with external power grid equipment, and also provides operators with a flat and safe installation and maintenance work surface.

[0014] 3. Since there is no need to increase the thickness of the cover steel plate to prevent deformation, the cost of raw materials such as steel is greatly saved, and the overall weight of the transformer is effectively reduced, thus reducing transportation and hoisting costs.

[0015] 4. The welding method provided by the present invention pre-presses the box cover into an arch shape using a C-shaped clamp and wooden block support, and performs spot welding and full welding under controlled conditions. This effectively controls the thermal deformation during the welding process, so that after welding is completed and the clamp is removed, the amount of springback deformation of the box cover body can be controlled within the allowable range. The processing technology is simple and the finished product quality is stable. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the arched reinforcing iron structure of the present invention.

[0017] Figure 2 This is a side view of the present invention.

[0018] Figure 3 This is a schematic diagram of the structure of the wooden block of the present invention.

[0019] Figure 4 This is a top view of the present invention.

[0020] In the diagram: 1. Box cover body; 2. Support platform; 3. Wooden block; 4. Rectangular reinforcing iron; 5. Arched reinforcing iron; 6. Switch flange; 7. High-pressure bushing flange; 8. Manhole flange; 9. Grounding bushing flange; 10. Pressure relief valve flange; 11. Upper screw; 12. Lower screw; 13. C-shaped frame. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Please see Figure 1-4 This invention provides a technical solution: a large transformer tank cover structure, including a tank cover body 1, a support platform 2, and C-shaped clamps. The tank cover body 1 is a rectangular plate structure and is mounted on the support platform 2. Two wooden blocks 3 are arranged longitudinally on the support platform 2. The lower surface of the tank cover body 1 is attached to the upper surface of the wooden blocks 3. Several C-shaped clamps are respectively straddling the two end edges of the tank cover body 1 and the support platform 2 to fix the tank cover body 1 to the support platform 2. The direction in which the tank cover body 1 extends along its length is longitudinal, and the direction in which it extends along its width is transverse. The longitudinal direction and the transverse direction are perpendicular to each other. The upper surface of the tank cover body 1 is welded with arched reinforcing irons 5 arranged along the transverse direction and several rectangular reinforcing irons 4 arranged along the longitudinal direction. Iron 5 and the rectangular reinforcing iron 4 form a slightly arched structure in the horizontal direction, with the middle higher than the two sides of the box cover body 1; the upper surface of the arched reinforcing iron 5 is a straight plane, and the lower surface of the arched reinforcing iron 5 is a welding surface. The welding surface has a height difference of 5mm from the center point to the end point. The arc of the arched reinforcing iron 5 satisfies the formula: R=(L / 2)²÷10, where L is the length of the arched reinforcing iron 5 and R is the radius of the arch arc, both in mm; several flanges are welded and fixed on the box cover body 1, including a switch flange 6, a high-voltage bushing flange 7, a manhole flange 8, a grounding bushing flange 9, and a pressure relief valve flange 10; a welding method for a large transformer box cover structure, applied to the large transformer box cover structure according to any one of claims 1-3, the welding method includes the following steps: S1. Place two wooden blocks 3 longitudinally on the support platform 2, place the box cover body 1 on the wooden blocks 3, set several C-shaped clamps at both ends of the box cover body 1, apply downward pressure to both ends of the box cover body 1 through the C-shaped clamps, and press the box cover body 1 into an arch shape. S2. Spot weld the flange onto the box cover body 1, spot weld the arched reinforcing iron 5 along the transverse direction, and spot weld the rectangular reinforcing iron 4 along the longitudinal direction, so that the box cover forms a height that is slightly higher in the middle than on both sides. S3. Fully weld all flanges and reinforcing irons. After the welds have cooled, remove the C-shaped clamps. The arched reinforcing iron 5 prevents the box cover body 1 from springing back and deforming. The C-shaped clamp includes a C-shaped frame 13 and an upper screw 11 and a lower screw 12 respectively disposed on the C-shaped frame 13. The C-shaped frame 13 spans between the edge of the box cover body 1 and the support platform 2. The lower screw 12 abuts against the support platform 2 for fixing the C-shaped clamp to the support platform 2. The upper screw 11 abuts against the upper surface of the box cover body 1, and pressure is applied to the box cover body 1 by tightening the upper screw 11.

[0023] Those skilled in the art can connect the components in this case sequentially. The specific connection and operation sequence should refer to the working principle described below. The detailed connection methods are well-known technologies in the field. The working principle and process are mainly described below.

[0024] Example: During long-term operation, the static pressure generated by the internal insulating oil and the thermal expansion and contraction caused by temperature changes will subject the tank cover to repeated alternating loads. The tank cover body 1 is usually a large-area thin plate structure, which is prone to plastic deformation under continuous internal pressure, resulting in depressions on the surface of the tank cover. In outdoor environments, water can easily accumulate in the depressions, accelerating corrosion of the tank cover surface. At the same time, the low-lying areas formed by deformation inside the tank cover can easily accumulate gas, affecting the insulation performance and operational safety of the transformer. To solve this problem, this example sets an arched reinforcing iron 5 and a rectangular reinforcing iron 4 on the upper surface of the tank cover body 1, so that the tank cover body 1 forms a slightly arched structure with the middle higher than the two sides. Through the action of the arched reinforcing iron 5, the flat-top oil tank can achieve the goal of preventing gas accumulation inside and water accumulation outside without increasing the thickness of the steel plate.

[0025] like Figure 1 As shown, the upper part of the arched reinforcing iron 5 is a straight plane, and the lower welding surface has a height difference of 5mm from the center point to the end point. This height difference is the pre-arch amount provided by the arched reinforcing iron 5 in the cross-section. The arc of the arched reinforcing iron 5 is cut into the corresponding R=(L / 2)²÷10 arc by a laser cutting machine according to the length L of the reinforcing iron, where L is the length of the arched reinforcing iron 5 and R is the arc radius of the arch, both in mm. The significance of this formula is that no matter how the size of the box cover body 1 changes, as long as the length of the arched reinforcing iron 5 is determined, the matching arc radius can be calculated by this formula, so that the pre-arch amount is always kept within a reasonable range, ensuring that box covers of different specifications can obtain a consistent pre-arch effect. There is no need to design molds or tooling separately for each size, making processing and production convenient and saving costs.

[0026] The rectangular reinforcing iron 4 is arranged longitudinally and intersects with the transverse arched reinforcing iron 5, so that the box cover is slightly higher in the middle than on both sides, providing support for the box cover body 1 in both longitudinal and transverse directions, so that the box cover body 1 has sufficient bending stiffness in both longitudinal and transverse directions, avoiding the problem of insufficient stiffness in one direction when the box cover is reinforced in one direction.

[0027] The welding method for the above-mentioned box cover structure includes the following steps: S1. Secure the lid to the platform: like Figures 2 to 3 As shown, two wooden blocks 3 are placed on the support platform 2 along the long axis, and the box cover body 1 is placed on top of the wooden blocks 3. The wooden blocks 3 provide support, suspending the middle of the box cover body 1 in the air, creating deformation space for subsequent pressure application. The C-shaped clamp is fixed to the platform with the lower screw 12, and the upper screw 11 applies pressure downward to both ends of the box cover, pressing the box cover into an arch shape. The advantage of using the C-shaped clamp for pressure application is that the number of clamps can be flexibly increased or decreased according to the length of the box cover body 1, the pressure can be precisely controlled by the screw screw insertion amount, the operation is simple and no large hydraulic equipment is required, making it particularly suitable for on-site construction conditions.

[0028] S2, Spot welding positioning: like Figure 4 As shown, with the box cover body 1 held in an arched state by the C-shaped clamp, the switch flange 6, high-pressure bushing flange 7, manhole flange 8, grounding bushing flange 9, pressure relief valve flange 10, etc. are spot welded and fixed on the box cover. The arched reinforcing iron 5 is spot welded and fixed along the short axis of the box cover, and the rectangular reinforcing iron 4 is spot welded and fixed along the long axis, so that the box cover forms a height that is slightly higher in the middle than on both sides. The purpose of spot welding is to temporarily fix each component to the box cover body 1 to ensure that each component will not be displaced due to thermal deformation or its own weight during the subsequent full welding process.

[0029] S3, Full weld reinforcement: All flanges and reinforcing irons are fully welded, with the reinforcing irons welded first and then the flanges. Welding proceeds from the center outwards to both ends to effectively control welding deformation. After the weld cools to room temperature, the C-shaped clamps are removed. Due to the effect of the arched reinforcing iron 5, the springback deformation of the cover is effectively controlled within the allowable range. The arc structure of the arched reinforcing iron 5 itself transmits the supporting force to the cover body 1 through the weld, continuously applying an upward supporting force to the cover body 1, thereby maintaining the arched state of the cover body 1. This is the principle of the present invention to prevent springback with reinforcing iron. The reinforcing iron is not only a structural reinforcement but also a shape retainer. After the clamps are removed, it takes over the shaping function of the clamps, eliminating the need for additional pressure holding processes and facilitating processing and production.

[0030] The transformer box cover manufactured by the above method achieves the effect of preventing air accumulation inside and water accumulation outside without increasing the thickness of the steel plate. After the outer surface of the box cover forms a slight arch, rainwater can flow away naturally without water accumulation.

[0031] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, the phrase "comprising an element defined as..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0032] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A large transformer tank cover structure, characterized in that, The box includes a lid body (1), a support platform (2), and C-shaped clamps. The lid body (1) is a rectangular plate structure and is set on the support platform (2). Two wooden blocks (3) are arranged longitudinally on the support platform (2). The lower surface of the lid body (1) is attached to the upper surface of the wooden blocks (3). Several C-shaped clamps are respectively straddled between the two ends of the lid body (1) and the support platform (2) to fix the lid body (1) on the support platform (2). The lid body (1) extends longitudinally along its length and laterally along its width. The longitudinal direction and the lateral direction are perpendicular to each other. The upper surface of the lid body (1) is welded with an arched reinforcing iron (5) arranged laterally and several rectangular reinforcing irons (4) arranged longitudinally. The arched reinforcing iron (5) and the rectangular reinforcing irons (4) make the lid body (1) form a slightly arched structure in the lateral direction with the middle higher than the two sides.

2. The large transformer tank cover structure according to claim 1, characterized in that, The upper part of the arched reinforcing iron (5) is a straight plane, and the lower part of the arched reinforcing iron (5) is a welding surface. The welding surface has a height difference of 5mm from the center point to the end point. The arc of the arched reinforcing iron (5) satisfies the formula: R=(L / 2)²÷10, where L is the length of the arched reinforcing iron (5) and R is the arc radius of the arch, both in mm.

3. The large transformer tank cover structure according to claim 1, characterized in that, Several flanges are welded and fixed on the box cover body (1), including a switch flange (6), a high-pressure bushing flange (7), a manhole flange (8), a grounding bushing flange (9), and a pressure relief valve flange (10).

4. A welding method for a large transformer tank cover structure, applied to the large transformer tank cover structure described in any one of claims 1-3, characterized in that, The welding method includes the following steps: S1. Place two wooden blocks (3) longitudinally on the support platform (2), place the box cover body (1) on the wooden blocks (3), set several C-shaped clamps at both ends of the box cover body (1), apply downward pressure to both ends of the box cover body (1) through the C-shaped clamps, and press the box cover body (1) into an arch shape. S2. Spot weld the flange on the box cover body (1), spot weld the arched reinforcing iron (5) along the transverse direction, and spot weld the rectangular reinforcing iron (4) along the longitudinal direction, so that the box cover forms a height that is slightly higher in the middle than on both sides. S3. Weld all flanges and reinforcing irons fully. After the welds have cooled, remove the C-shaped clamps. The arched reinforcing iron (5) prevents the box cover body (1) from springing back and deforming.

5. The welding method for a large transformer tank cover structure according to claim 4, characterized in that, The C-shaped clamp includes a C-shaped frame (13) and an upper screw (11) and a lower screw (12) respectively disposed on the C-shaped frame (13). The C-shaped frame (13) spans between the edge of the box cover body (1) and the support platform (2). The lower screw (12) abuts against the support platform (2) to fix the C-shaped clamp to the support platform (2). The upper screw (11) abuts against the upper surface of the box cover body (1) and applies pressure to the box cover body (1) by tightening the upper screw (11).

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