Flexible conductive connection integrated structure and preparation method thereof, and primary and secondary fusion solid-sealed polar pole

Abstract

The invention relates to the technical field of high-voltage power transmission and distribution equipment, and discloses a flexible conductive connection integrated structure, a preparation method thereof and a primary and secondary fusion solid-sealed polar pole. The structure comprises an upper fixed terminal, a lower fixed terminal and at least one flexible connecting ring connected between the upper fixed terminal and the lower fixed terminal. The flexible connecting ring is wound by an annealed and toughened strip-shaped copper sheet and is seamlessly welded end to end to form an O-shaped ring, and the material of the flexible connecting ring has high toughness and high conductivity. And the ring body and the two terminals realize low-resistance contact through a precisely polished contact surface and a silver coating, and are fixed by double-side clamping and brazing. In the application of the pole, the integrated structure is connected with the moving end of the vacuum arc-extinguishing chamber, is connected with the lower wire outlet rod, and is coated by the fixing and sealing piece. According to the design, by controlling the width-to-thickness ratio, the radius-to-thickness ratio and the height-to-width ratio of the ring and applying proper pre-compression / stretching, excellent electrical performance, fatigue resistance and space adaptability are achieved, and the requirements of primary and secondary fusion equipment for long-life reliable conductive connection are met.

Description

Technical Field

[0001] This invention relates to the field of high-voltage power transmission and distribution equipment technology, and more specifically, to a flexible conductive connection structure and preparation method for high-voltage circuit breakers, particularly suitable for solid-sealed poles with deep integration of primary and secondary components. Background Technology

[0002] With the deepening of smart grid construction, the integrated primary and secondary circuit breaker has been widely used due to its advantages such as high integration, powerful functions and compact size.

[0003] In such equipment, to achieve deep integration and reliable isolation between the primary conductive circuit and the secondary intelligent components, and to accommodate the mechanical displacement of the vacuum interrupter during opening and closing operations and temperature changes, a reliable flexible electrical connection structure must be installed internally. This structure must withstand reciprocating tension, compression, and possible torsional deformation over a long period within an extremely compact space, while maintaining extremely low and stable contact resistance, placing extremely high demands on mechanical fatigue life (typically requiring more than 100,000 operations) and electrical reliability.

[0004] In existing technologies, flexible connections often employ braided copper wire flexible connections or copper foil laminate structures. For example, common braided copper wire flexible connections are made by weaving multiple strands of fine copper wires together, utilizing their loose structure to achieve flexibility. However, in specific application scenarios involving deep integration at both primary and secondary levels, such traditional structures reveal significant drawbacks:

[0005] First, its mechanical fatigue life is limited. Under long-term, high-frequency reciprocating bending, a single copper wire is prone to breakage due to stress concentration, resulting in increased resistance or even overall failure.

[0006] Secondly, its deformation mode is uncontrollable and the bending direction is random. In a compact installation space, it is easy to interfere with surrounding insulating or conductive parts, which may lead to short circuit or insulation risks.

[0007] Furthermore, the space utilization rate is low. In order to ensure sufficient current-carrying cross-sectional area and bending freedom, a large swing space is often required, which goes against the design trend of miniaturization and compactness of equipment.

[0008] Although some technologies have attempted to improve performance by using O-ring copper foil structures, if ordinary copper materials or unoptimized structural parameters are used, problems such as weld cracking, stress concentration leading to material fatigue, and crack propagation are still likely to occur under long-term complex stress cycles. This makes it difficult to meet the stringent requirements of next-generation high-voltage circuit breakers for ultra-long life and high reliability of flexible connection components.

[0009] Therefore, how to design a flexible conductive connection structure that combines ultra-long mechanical life, controllable deformation mode, excellent electrical performance and high space utilization, and match it with a precision manufacturing process that can ensure its performance consistency, has become a key technical problem that urgently needs to be solved in this field. Summary of the Invention

[0010] This invention aims to overcome the shortcomings of existing technologies and provide a flexible conductive connection integrated structure, its preparation method, and a solid-sealed pole for applying this structure. The purpose of this invention is to solve the problems of short mechanical fatigue life, uncontrollable deformation, and low space utilization of traditional flexible electrical connections within the compact space of primary and secondary integrated circuit breakers, thereby providing a flexible conductive connection solution with ultra-long mechanical life, stable and controllable deformation, excellent electrical performance, and suitability for compact installation.

[0011] To achieve the above objectives, the present invention provides the following technical solution:

[0012] In a first aspect, the present invention provides a flexible conductive connection integrated structure comprising an upper fixed terminal, a lower fixed terminal, and at least one flexible connecting ring connected between the two; the flexible connecting ring is formed by winding toughened copper foil, and its two ends are seamlessly welded together to form a ring structure; the upper fixed terminal and the lower fixed terminal are respectively fixedly connected to the upper and lower ends of the flexible connecting ring by double-sided clamping and brazing; the contact surfaces of the flexible connecting ring, the upper fixed terminal and the lower fixed terminal are provided with a silver plating layer.

[0013] In addition to the above-mentioned technical features, the present invention has also made optimizations and improvements in the following aspects:

[0014] As a preferred embodiment of the present invention, the initial copper sheet is TU1 oxygen-free copper or T2 copper that has undergone annealing and initial treatment. The Vickers hardness HV0.2 of the initial copper sheet is between 45 and 65, the elongation after fracture A11.3 is ≥40%, and the volumetric conductivity is ≥58MS / m.

[0015] As a preferred embodiment of the present invention, the flexible connecting ring is configured as an O-shape, wherein the O-shaped flexible connecting ring is formed by winding a strip of initial copper foil into a ring structure having at least one turn; the width-to-thickness ratio of the strip of initial copper foil is greater than 10:1, and the ratio of the inner radius R of the O-shaped flexible connecting ring to the copper foil thickness t satisfies: R / t>50.

[0016] As a preferred embodiment of the present invention, the ratio of the height H to the width W of the O-ring in its initial state satisfies: 0.5 < H / W < 2.0.

[0017] As a preferred embodiment of the present invention, the seamless welding is electron beam welding or molecular diffusion welding; after welding, the weld area is subjected to stress-relief annealing treatment.

[0018] As a preferred embodiment of the present invention, the surface roughness Ra value of the contact surfaces of the upper fixed terminal, the lower fixed terminal and the O-ring flexible connecting ring is ≤0.8μm.

[0019] As a preferred embodiment of the present invention, the O-ring flexible connector, after being assembled with the upper and lower fixed terminals, has a pre-compression amount or a pre-stretch amount, wherein the pre-compression amount or pre-stretch amount is 5% to 15% of its initial height.

[0020] As a preferred embodiment of the present invention, the upper fixed terminal is electrically connected to the moving end of the vacuum interrupter, the lower fixed terminal is electrically connected to the lower lead rod, and the entire integrated structure is covered with a solidified insulating component.

[0021] Secondly, the present invention provides a method for preparing the flexible conductive interconnect integrated structure as described above, comprising the following steps:

[0022] S1: Select strip-shaped initial copper foil that meets performance requirements;

[0023] S2: Copper foil is rolled into an O-ring flexible connector and its two ends are welded into a seamless joint by electron beam welding or molecular diffusion welding.

[0024] S3: Perform stress-relieving annealing on the welded O-ring flexible connector;

[0025] S4: The outer surface of the O-ring and the contact area of ​​the upper and lower fixed terminals are precision polished to make the surface roughness Ra value ≤ 0.8μm;

[0026] S5: Electroplating is performed on the outer surface of the polished O-ring flexible connector and the contact area of ​​the upper and lower fixed terminals to form a silver plating layer with a thickness of ≥3μm;

[0027] S6: The upper and lower ends of the silver-plated O-ring flexible connector are respectively assembled with the upper and lower fixed terminals by double-sided clamping, and the connection is reinforced by silver-copper brazing or high-temperature soldering.

[0028] Thirdly, the present invention provides a primary and secondary fusion solid-sealing pole, including a vacuum interrupter, a lower lead rod and a solid-sealing component, and also includes a flexible conductive connection integrated structure as described in any of the first aspects above.

[0029] The upper fixed terminal of the flexible conductive connection integrated structure is electrically connected to the lower end of the vacuum interrupter, and the lower fixed terminal of the flexible conductive connection integrated structure is electrically connected to the upper end of the lower outlet rod; the outer walls of the vacuum interrupter, the flexible conductive connection integrated structure, and part of the lower outlet rod are integrally covered by the sealing component.

[0030] Compared with existing technologies, the flexible conductive connection integrated structure and its preparation method provided by this invention, as well as the solid-sealed electrode post using this structure, have the following significant advantages:

[0031] 1. Achieve ultra-long mechanical fatigue life and high reliability

[0032] This invention, the "Type O Flexible Connecting Ring," is made of toughened copper foil with specific properties (HV0.2: 45-65, A11.3 ≥ 40%), which fundamentally endows the material with excellent fatigue resistance due to its extremely high ductility. Through "seamless welding" and "stress-relief annealing" processes, weak points in the joint are eliminated, resulting in uniform mechanical properties of the ring. A unique geometric design (R / t > 50) ensures that stress is evenly distributed within the material during reciprocating deformation, greatly avoiding stress concentration. The "pre-compression or pre-tension" design during assembly (5%-15% of the free height) ensures reliable initial contact and provides buffer space for operational deformation. The synergistic effect of these features enables the connecting structure to stably withstand over 100,000 cycles of rated stroke reciprocating motion, meeting the stringent requirements of primary and secondary fusion equipment for the ultra-long lifespan of core components.

[0033] 2. The deformation mode is stable and controllable, with extremely strong spatial adaptability.

[0034] The structure of the "Type O flexible connecting ring" of this invention determines that its deformation mode under stress (such as axial displacement caused by the opening and closing of a vacuum interrupter) is regular and predictable radial expansion or uniform bending, completely avoiding the randomness and uncontrollability of deformation of traditional braided flexible connections. Combined with an optimized aspect ratio (0.5 < H / W < 2.0), this structure can achieve the required stroke in an extremely compact installation space (such as inside a solid-sealed pole) without interfering with surrounding components, making it particularly suitable for highly integrated "primary and secondary fusion solid-sealed poles".

[0035] 3. Possesses excellent and stable electrical performance.

[0036] First, the use of a high-conductivity substrate (volume conductivity ≥58 MS / m, i.e., ≥98% IACS) ensures low bulk resistance. Second, the "double-sided clamping and brazing" connection method, combined with extremely low surface roughness (Ra≤0.8μm) and a fully covered silver plating layer (thickness ≥3μm), forms a large-area, low-resistance, and oxidation-resistant reliable electrical contact interface. The seamless welded structure also avoids localized overheating caused by uneven joint resistance. These technical features together ensure that the connection structure has low and stable contact resistance, excellent temperature rise performance, and low power loss throughout its entire lifespan.

[0037] 4. Precision manufacturing process, resulting in high product consistency and reliability.

[0038] The preparation method配套 to the present invention defines a complete quality control chain. From material selection, forming and welding, stress relief treatment, to precision polishing, controllable electroplating, and finally to non-destructive assembly and full inspection, each step has clear process parameters and quality standards (such as surface roughness, coating thickness, no mechanical damage). This standardized precision manufacturing process ensures that each product has highly consistent performance and high reliability, facilitating large-scale industrial production and application.

[0039] 5. Good environmental adaptability and durability

[0040] The silver plating layer on the surface not only reduces the contact resistance but also provides excellent antioxidant and corrosion protection, enabling the connection structure to work stably for a long time under the influence of the microenvironment that may exist in high-voltage switchgear. The overall structure is designed firmly without vulnerable parts, further enhancing its overall durability under complex working conditions.

[0041] 6. Integration of high-performance primary and secondary integrated solid-insulated poles

[0042] When this flexible conductive connection integrated structure is applied to the "primary and secondary integrated solid-insulated pole", its compact, reliable, and long-life characteristics are fully exerted. As the key dynamic conductive path connecting the vacuum interrupter and the lower outgoing rod, while ensuring excellent electrical connection, it perfectly adapts to the mechanical displacement during operation, and its stable deformation does not affect the integrity of the surrounding solid-insulated components, thus providing core component support for manufacturing high-performance, high-reliability, and maintenance-free intelligent high-voltage switchgear.

[0043] In summary, by combining the "O-shaped flexible structure of specific materials" with the "precision controllable manufacturing process", the present invention systematically solves the core problems existing in traditional flexible electrical connections in high-voltage compact switchgear, such as short fatigue life, uncontrollable deformation, and unstable electrical contact, achieving a comprehensive breakthrough in mechanical life, electrical performance, environmental adaptability, and product consistency. Brief Description of the Drawings

[0044] Figure 1 is the overall structure schematic diagram of the flexible conductive connection integrated structure of the present invention;

[0045] Figure 2 is the installation and use state diagram of the flexible conductive connection integrated structure of the present invention.

[0046] In the figure: 1, upper fixed terminal; 2, lower fixed terminal; 3, flexible connection ring. Detailed Embodiments

[0047] The following describes the preferred embodiments of the present invention with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention and are not used to limit the present invention.

[0048] I. Explanation of descriptive terms used in this invention

[0049] The embodiments provided in conjunction with the technical solutions of this invention are intended to make the invention more thorough and complete, and to fully express the scope of the invention to those skilled in the art. It should be noted that unless otherwise specifically stated in this invention, the relative arrangements of components described in these embodiments should be interpreted as merely exemplary and not as a limitation on the technical solutions of this invention.

[0050] In this invention, when directional terms such as "up," "down," "left," "right," "bottom," and "top" are used, they are defined relative to the directions shown in the accompanying drawings and are used only to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly. These or other directional terms should not be construed as restrictive terms.

[0051] In this invention, the terms "a," "an," "an," "the," and similar words used do not indicate quantity limitations and can represent singular or plural. The terms "comprising," "including," "having," and any variations thereof used in this invention are intended to cover non-exclusive inclusion; the terms "first," "second," "third," etc., used in this invention are merely to distinguish similar objects and do not represent a specific ordering of objects.

[0052] In this invention, when a specific device is described as being located between a first device and a second device, an intermediary device may or may not be present between the specific device and the first or second device. When a specific device is described as being connected to other devices, the specific device may be directly connected to the other devices without an intermediary device, or it may be not directly connected to the other devices but have an intermediary device.

[0053] Furthermore, this invention does not discuss in detail the technologies and equipment known to those skilled in the art, but where appropriate, such technologies and equipment should be considered part of the specification.

[0054] II. The core technical problem to be solved by the technical solution of this application

[0055] Existing technologies present significant challenges in the flexible conductive connections of circuit breakers deeply integrated into primary and secondary circuits in smart grids. Traditional braided copper wire flexible connections suffer from insufficient mechanical fatigue life; the copper wires are prone to breakage under prolonged repeated bending, leading to increased resistance or failure. Furthermore, their deformation modes are uncontrollable, easily interfering with surrounding components in compact spaces, posing risks of short circuits or insulation failure. In addition, this structure has low space utilization, requiring substantial sway space, which hinders the trend towards equipment miniaturization. While improved O-ring copper foil structures exist, using ordinary copper materials or without optimized parameters still easily leads to problems such as weld cracking, stress concentration, and fatigue cracking, failing to meet the stringent requirements of ultra-long lifespan and high reliability for high-voltage circuit breakers. Overall, current flexible connection structures face challenges in terms of lifespan, deformation control, electrical stability, and space utilization.

[0056] III. Based on the above problems, the present invention specifically provides a technical solution to solve these problems. The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments. It should be understood that these embodiments are only used to explain the present invention and are not intended to limit the scope of protection of the present invention.

[0057] Example 1: Specific Implementation of Flexible Conductive Connection Integrated Structure

[0058] This embodiment provides a specific flexible conductive connection integrated structure, which is mainly used in a 10kV primary and secondary integrated vacuum circuit breaker to connect the moving end of the vacuum interrupter to the lower outgoing line rod to compensate for the mechanical displacement caused by the opening and closing operations.

[0059] 1. Overall composition and connection relationships

[0060] The flexible conductive connection integrated structure includes an upper fixed terminal 1, a lower fixed terminal 2, and a flexible connecting ring 3 connecting the two. The upper surface of the upper fixed terminal 1 is provided with a threaded hole for fixing and electrically connecting to the moving end conductive rod of the vacuum interrupter by bolts.

[0061] The lower surface of the lower fixed terminal 2 is provided with a threaded hole for fixing and electrically connecting to the lower outgoing rod of the circuit breaker by bolts.

[0062] The flexible connecting ring 3 is configured as an O-type. The upper and lower end faces of the O-type flexible connecting ring are initially fixed by the clamping grooves of the upper fixed terminal 1 and the lower fixed terminal 2 through a double-sided large-area clamping method, and are finally solidified and electrically connected in the clamping area by brazing.

[0063] Material: The O-ring flexible connector is made of TU1 oxygen-free copper strip that has undergone annealing and toughening treatment. Its chemical composition meets the following requirements: Cu+Ag content ≥ 99.97%, oxygen content ≤ 0.003%.

[0064] The annealing process is as follows:

[0065] Under nitrogen protection, the temperature is raised to 450 ± 10 °C, held for 3 hours, and then cooled in the furnace to below 150 °C before taking out. The properties of the treated copper strip are as follows: Vickers hardness HV0.2 = 55 ± 5, elongation after fracture A11.3 = 42%, and volume conductivity = 59.5 MS / m.

[0066] The O-shaped flexible connection ring of this application combines "high conductivity" and "high ductility", which is difficult to achieve simultaneously with traditional soft connection materials (such as hard copper strips or ordinary soft copper), laying the core material foundation for the subsequent ultra-long fatigue life.

[0067] Structural dimensions:

[0068] The thickness of the copper strip t = 0.25 mm, the width (i.e., the axial height of the ring) W = 10.0 mm, and the width-thickness ratio is 40:1. The copper strip is wound into a closed ring of 2 turns on a precision winding die. After forming, the inner radius of the ring R = 15.0 mm, then R / t = 60, strictly meeting and significantly exceeding the design requirement of R / t > 50. This large curvature radius design significantly reduces the maximum tensile strain of the outer fibers when the copper strip is bent, fundamentally avoiding plastic accumulation and fatigue damage during the reciprocating deformation of the material.

[0069] The height H of the O-shaped flexible connection ring in the free and unloaded state is 18.0 mm, and its width (the thickness of the ring body section) is 5.0 mm. Calculated, H / W = 1.8, which is in the middle of the preferred range of 0.5 < H / W < 2.0. This ratio ensures that when the ring is axially loaded, it can generate sufficient elastic deformation to absorb displacement, and at the same time ensures the lateral stability of the structure, avoiding instability and distortion.

[0070] 2. Forming and connection process

[0071] After winding and forming, the head and tail对接 ends of the copper strip are connected by molecular diffusion welding.

[0072] Process parameters: temperature 500 °C, pressure 15 MPa, holding and pressurizing time 30 minutes, vacuum environment. This process realizes the diffusion bonding between atoms in the solid state, and the formed joint has no casting structure, no porosity and slag inclusion, and its conductivity and mechanical properties are basically the same as those of the base material, completely eliminating defects such as grain coarsening and composition segregation that may exist in fusion welded joints. After welding, the whole component is subjected to stress relief annealing at 400 °C for 2 h.

[0073] Surface treatment:

[0074] Precision polishing: The entire outer surface and both end clamping surfaces of the O-shaped flexible connection ring are mechanically polished using gradually refined sand belts (from 400# to

[0075] Silver plating: A cyanide silver plating process is used. Rigorous activation and cleaning are performed before plating. Plating parameters: silver ion concentration 4 g / L, current density 0.8 A / dm², temperature 25℃, plating time 30 minutes. A uniform, dense, and strongly bonded silver plating layer is formed on all outer surfaces of the O-ring flexible connector and the clamping surfaces of the upper and lower fixed terminals, with a measured thickness of 3.8 μm (≥3 μm). This thick silver plating layer is crucial for maintaining low contact resistance and corrosion resistance of this structure under harsh environments (such as high temperature and high humidity) over a long period.

[0076] 3. Upper fixed terminal 1 and lower fixed terminal 2

[0077] The upper fixed terminal 1 and the lower fixed terminal 2 are made of T2 copper. The contact surfaces of the clamping grooves are CNC milled and polished and silver-plated to the same standard, with a surface roughness Ra=0.65μm and a silver plating layer thickness of 3.5μm. The contact surfaces of the upper and lower terminals achieve a "mirror fit" with the contact surface of the O-ring flexible connector, maximizing the effective contact area.

[0078] Non-critical areas of the terminals can be tin-plated or coated with anti-rust oil for protection.

[0079] 4. Final assembly process:

[0080] S1: Place the silver-plated O-ring (3) into the clamping groove of the lower fixed terminal 2.

[0081] S2: Cover the upper fixing terminal 1, aligning the clamping groove with the upper end of the O-ring. Apply a uniform clamping force from both sides using a special clamp. At this point, the height of the O-ring is measured to be compressed to approximately 16.7 mm, resulting in a pre-compression of approximately 7.2% ((18.0-16.7) / 18.0) (within the range of 5%-15%). This pre-compression ensures that all contact surfaces remain in tight contact without gaps or micro-movements after installation and during operational vibrations.

[0082] S3: Molten silver-copper brazing filler metal is injected through the injection hole on the side of the clamping groove, and brazing is performed under a protective atmosphere. The brazing filler metal fully fills the clamping interface along capillary action, and forms a strong metallurgical bond after cooling.

[0083] S4: Conduct 100% visual inspection of the finished product (to ensure there are no bumps or scratches), and sample the product for contact resistance testing (required to be ≤5μΩ) and X-ray non-destructive testing (to check the quality of brazing filler).

[0084] Based on the above technical design, the various technical features in this embodiment, through mutual synergy, solve the three major problems pointed out in the background art:

[0085] Addressing the issue of "limited fatigue life": the high-ductility substrate (A11.3=42%) provides a large reserve of plastic deformation capacity; the large R / t ratio (=60) reduces working stress to extremely low levels; molecular diffusion weld joints eliminate weak points; and the pre-compression ensures that the working stress cycle is within a favorable compression-recovery range. Through the synergistic design of these technical features, the possibility of stress concentration and plastic strain accumulation is minimized.

[0086] Bench tests show that, under simulated 8mm stroke and 60 cycles per minute conditions, the connection structure successfully passed 150,000 reciprocating motions without cracking, with a resistance change rate of <2%, and a lifespan more than 10 times that of traditional braided flexible connections, achieving the unexpected effect of "ultra-long mechanical lifespan".

[0087] Regarding the issue of "uncontrollable deformation": The axisymmetric structure of the O-ring flexible connector inherently determines the deterministic nature of its deformation mode. A precisely controlled H / W ratio (1.8) further constrains the deformation pattern, causing it to primarily undergo uniform radial expansion during axial compression and uniform radial contraction during axial tension. This stable and predictable deformation trajectory ensures that it will never interfere with surrounding insulating cylinders, sensors, etc., within the limited space of the sealed electrode, thus solving the problem of random oscillation.

[0088] Addressing the issue of "low space utilization": This design utilizes a thin, wide copper strip (t=0.25mm, W=10mm) to provide sufficient conductive cross-section within a relatively small radial space (outer diameter approximately 35mm). Simultaneously, the deformation mode of the O-ring flexible connector allows it to absorb the same axial displacement with a significantly smaller overall bending space compared to braided wires or laminates requiring large bending radii. Therefore, it can be easily embedded into the extremely compact "primary and secondary fusion solid-sealed pole," achieving high space utilization.

[0089] Example 2: Method for fabricating flexible conductive interconnect integrated structures

[0090] This embodiment details the specific steps and parameter control of the low-loss production process, which is key to ensuring high performance and high consistency of the product.

[0091] S1: Material Selection

[0092] TU1 oxygen-free copper strip conforming to GB / T5231 was selected, with the initial state being hard (H-state). Key performance indicators were: thickness 0.25±0.01mm, width 10.0±0.1mm, and conductivity ≥58.5MS / m. Spectral composition analysis and preliminary mechanical property testing were performed.

[0093] S2: Annealing and toughening

[0094] Place the copper strip into a vacuum annealing furnace and evacuate it to a vacuum level of 1×10⁻⁶. -2 After Pa, high-purity nitrogen is introduced as a protective atmosphere. The temperature is raised to 460℃ at a rate of 100℃ / h, held for 3.5 hours, and then slowly cooled to below 100℃ at a rate not exceeding 50℃ / h before being removed from the furnace. This process aims to obtain a uniform recrystallized structure, achieving the best match between hardness (HV0.2 approximately 50-60) and elongation (≥40%), rather than simply softening.

[0095] S3: Winding and Welding Winding

[0096] On a specialized winding machine, the toughened copper strip is wound twice along the mandrel (30mm in diameter) to ensure that the coils fit tightly without gaps.

[0097] Welding: The mating surfaces of the wound body are precision milled flat, and then electron beam welding is performed. Welding parameters: accelerating voltage 60kV, beam current 15mA, welding speed 500mm / min, vacuum degree 5×10 -3 Pa. The high energy density of the electron beam and the vacuum environment ensure a large weld depth-to-width ratio, a narrow heat-affected zone, and extremely low oxide content, resulting in near-perfect joint quality.

[0098] S4: Stress-relieving annealing

[0099] The welded O-ring flexible connector assembly is then placed back into the vacuum furnace and held at 380°C for 2 hours, followed by furnace cooling. This step is specifically designed to eliminate localized residual stress caused by welding, preventing it from becoming a crack initiation point during subsequent deformation.

[0100] S5: Precision Polishing

[0101] An automated magnetic polishing machine was used, employing a mixture of stainless steel needles and a special polishing slurry as the polishing medium, to polish the O-ring flexible connector. After polishing, five points were randomly inspected using a white light interferometer, and the surface roughness Ra value of all points had to be ≤0.7μm.

[0102] S6: Pretreatment before electroplating: including cathode electrolytic degreasing, acid activation, and pre-plating silver base.

[0103] Silver electroplating: A low-stress, semi-bright cyanide silver plating process is used. The main salt concentration, temperature (28±2℃), and current density (0.5A / dm²) are strictly controlled. The plating bath performance is monitored regularly using a Hall effect test. The electroplating time is 40 minutes, ensuring a coating thickness within the range of 3-4μm, with a thickness uniformity error ≤±0.3μm. After plating, a triple countercurrent rinsing and hot pure water rinsing are performed, followed by an anti-discoloration treatment.

[0104] S7: Assembly and Brazing: The upper and lower fixed terminals (whose contact surfaces have been pre-polished and silver-plated, Ra≤0.7μm) are assembled with the O-ring in a nitrogen-protected glove box. A constant clamping force is applied using a torque wrench and a special fixture to ensure that the pre-compression is within 10%±2%.

[0105] High-frequency induction brazing is employed, using sheet-shaped silver-copper brazing filler metal (BAg35CuZn) pre-placed in the filler metal reservoir of the clamping groove. Induction heating is rapid and localized, melting and filling the gap with the filler metal within 30 seconds, followed by cooling in a hydrogen-nitrogen protective gas mixture. This process has low heat input and minimal impact on the base material and plating.

[0106] S8: Appearance inspection: 100% inspection under a 10x magnifying glass, requiring no visible dents, scratches, or peeling of the plating.

[0107] Non-destructive testing: Perform ultrasonic C-scan on the brazed area to ensure a brazing rate of ≥95%.

[0108] Electrical performance: Samples were subjected to high current temperature rise test (1.1 times the rated current, ΔT≤65K) and contact resistance test (≤4μΩ).

[0109] The effects of this process embodiment are illustrated as follows: Every link in this process chain is designed around the core objective of "low loss" (i.e., low mechanical performance loss and low electrical performance loss). In particular, the series connection and parameter coupling of the four core process steps—"annealing and toughening," "molecular / electron beam welding + stress-relief annealing," "precision polishing and thick silver plating," and "controllable pre-pressure assembly"—ensures that the final product not only achieves breakthroughs in individual performance indicators but also guarantees long-term performance stability and batch consistency, which is unparalleled by traditional workshop-style flexible connector production.

[0110] Example 3: Primary and Secondary Fusion Solid-Sealing Terminal of Flexible Conductive Connection Integrated Structure

[0111] This embodiment demonstrates the application of the flexible conductive connection integration structure described in Embodiment 1 to a specific product.

[0112] 1. Overall Structure

[0113] The primary and secondary fusion solid-sealed pole comprises, from top to bottom: a vacuum interrupter chamber and a moving conductive rod at its lower end.

[0114] The flexible conductive connection integrated structure is the structure described in Embodiment 1. Its fixed terminals are connected to the moving conductive rod via bolts.

[0115] The lower lead rod is connected at its upper end to the lower fixed terminal of the flexible conductive connection integrated structure via bolts.

[0116] The solidified insulation component is made of epoxy resin through APG process in one step, completely covering the lower part of the vacuum interrupter, the entire flexible conductive connection integrated structure, and the upper part of the lower lead rod, forming an integral molded unit with high mechanical strength and reliable insulation performance.

[0117] Integrated sensors, such as displacement sensors or temperature sensors, are embedded in the inner wall of a solidified insulating component, close to the flexible connection structure, for online monitoring of its status.

[0118] 2. Work process and technical effects

[0119] When the circuit breaker trips, the moving contact of the vacuum interrupter causes the moving end conductive rod to move upward by approximately 8mm. At this time, the O-ring of the flexible conductive connection integrated structure is stretched, increasing in height and decreasing in width. Because the deformation of the O-ring is stable and controllable, the entire process is smooth and does not generate severe localized impact stress on the solidified insulation components. Simultaneously, the current continues to flow continuously through the path of "moving end conductive rod → upper fixed terminal → O-ring → lower fixed terminal → lower outgoing rod," with minimal change in contact resistance.

[0120] The synergistic effect and technological advancement of this embodiment are reflected in the following aspects: Revolution in the reliability of the pole throughout its entire life cycle: The mechanical life of the flexible connection structure is more than 150,000 cycles, which matches or even exceeds the electrical life of the vacuum interrupter of 100,000 cycles. This changes the previous situation where the connection component was the weakest link, so that the overall reliability of the solid-sealed pole is determined by the vacuum interrupter, which greatly improves the product grade and market competitiveness.

[0121] Achieving true "deep integration": The stable deformation of the O-ring flexible connector provides a stable monitoring environment for the built-in integrated sensors. The sensors can measure displacement or temperature more accurately, and the data is free from noise caused by random vibrations of the connecting components. This enables the secondary intelligent components to more accurately sense the status of the primary circuit, achieving deep coupling of mechanical and electrical, primary and secondary circuits in terms of function and information.

[0122] Synergistic optimization of insulation and heat dissipation: The regular shape and smooth surface of the O-ring flexible connector allow the epoxy resin to be perfectly filled during the APG process, forming a bubble-free and defect-free insulating coating. At the same time, its excellent conductivity and silver plating layer result in less heat generation during operation and easy conduction to the terminals for dissipation, synergistically ensuring the insulation strength stability and low operating temperature rise of the terminal during long-term operation.

[0123] Improved assembly and maintainability: This integrated structure, provided as a standalone, rigorously tested module to the pole assembly line, simplifies the final assembly process and improves production efficiency and quality consistency. Throughout the pole's lifecycle, this connection structure is essentially maintenance-free.

[0124] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0125] Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them; when the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

Claims

1. A flexible conductive connection integrated structure, characterized in that, include: The upper fixed terminal (1), the lower fixed terminal (2), and at least one flexible connecting ring (3) connected between the two; the flexible connecting ring (3) is made of toughened copper foil and its two ends are seamlessly welded together to form a ring structure; the upper fixed terminal (1) and the lower fixed terminal (2) are respectively fixedly connected to the upper and lower ends of the flexible connecting ring (3) by double-sided clamping and brazing; the contact surfaces of the flexible connecting ring (3), the upper fixed terminal (1) and the lower fixed terminal (2) are provided with a silver plating layer.

2. The flexible conductive connection integrated structure according to claim 1, characterized in that, The toughened copper foil is TU1 oxygen-free copper or T2 copper that has undergone annealing and toughening treatment. The Vickers hardness HV0.2 of the toughened copper foil is between 45 and 65, the elongation after fracture A11.3 is ≥40%, and the volume conductivity is ≥58MS / m.

3. The flexible conductive connection integrated structure according to claim 1, characterized in that, The flexible connecting ring (3) is configured as an O-type, and the O-type flexible connecting ring is formed by winding a strip of toughened copper foil into a ring structure with at least one turn; the width-to-thickness ratio of the strip of toughened copper foil is greater than 10:1, and the ratio of the inner radius R of the O-type flexible connecting ring to the copper foil thickness t satisfies: R / t>50.

4. The flexible conductive connection integrated structure according to claim 1 or 3, characterized in that, The ratio of the height H to the width W of the O-ring in its initial state satisfies: 0.5 < H / W < 2.

0.

5. The flexible conductive connection integrated structure according to claim 1, characterized in that, The seamless welding is electron beam welding or molecular diffusion welding; after welding, the weld area is subjected to stress-relief annealing treatment.

6. The flexible conductive connection integrated structure according to claim 1, characterized in that, The surface roughness Ra value of the contact surfaces of the upper fixed terminal, the lower fixed terminal and the O-ring flexible connecting ring is ≤0.8μm.

7. The flexible conductive connection integrated structure according to claim 1, characterized in that, After being assembled with the upper and lower fixed terminals, the O-ring flexible connector has a pre-compression or pre-tension amount, which is 5% to 15% of its initial height.

8. The flexible conductive connection integrated structure according to claim 1, characterized in that, The upper fixed terminal is electrically connected to the moving end of the vacuum interrupter, and the lower fixed terminal is electrically connected to the lower output rod. The entire integrated structure is covered with a solidified insulating component.

9. A manufacturing process for preparing the flexible conductive connection integrated structure as described in any one of claims 1-8, characterized in that, Includes the following steps: S1: Select strip-shaped toughened copper foil that meets performance requirements; S2: Copper foil is rolled into an O-ring flexible connector and its two ends are welded into a seamless joint by electron beam welding or molecular diffusion welding. S3: Perform stress-relieving annealing on the welded O-ring flexible connector; S4: The outer surface of the O-ring flexible connector and the contact area of ​​the upper and lower fixed terminals are precision polished to make the surface roughness Ra value ≤ 0.8μm; S5: Electroplating is performed on the outer surface of the polished O-ring flexible connector and the contact area of ​​the upper and lower fixed terminals to form a silver plating layer with a thickness of ≥3μm; S6: The upper and lower ends of the silver-plated O-ring flexible connector are respectively assembled with the upper and lower fixed terminals by double-sided clamping, and the connection is reinforced by silver-copper brazing or high-temperature soldering.

10. A primary and secondary fusion solid-sealed pole, comprising a vacuum interrupter, a lower lead rod, and a sealing component, characterized in that, It also includes the flexible electrical connection mechanism as described in any one of claims 1 to 8; The upper fixed terminal of the flexible electrical connection mechanism is electrically connected to the lower end of the vacuum interrupter, and the lower fixed terminal of the long-life flexible electrical connection mechanism is electrically connected to the upper end of the lower outlet rod; the outer walls of the vacuum interrupter, the long-life flexible electrical connection mechanism, and part of the lower outlet rod are integrally covered by the sealing member.

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