A processing technology for fire-resistant shielded insulated busbars

Abstract

This invention relates to the field of insulating busbar technology and discloses a processing technology for a fire-resistant shielded insulating busbar, comprising the following steps: Step 1, conductor pretreatment: The outer surface of the busbar conductor is ground against each other using grinding rollers of a surface treatment machine to remove the oxide layer on the outer surface; Step 2, mica tape fixed-length longitudinal wrapping forming: The single-layer fire-resistant ceramic-clad mica tape is forced to undergo a gradually inward bending deformation by the gradual inner cavity of the fixed-length forming mold of the longitudinal wrapping forming machine, thereby wrapping the single-layer fire-resistant ceramic-clad mica tape over the outer surface of the busbar conductor. This processing technology for a fire-resistant shielded insulating busbar utilizes a double-sided grinding roller counteracting setting, which cancels out the grinding forces, preventing the busbar conductor from bending and deforming under unilateral force. Simultaneously, it removes the oxide layer from the conductor surface, reduces interfacial contact thermal resistance, and improves the insulation reliability and fire resistance stability of the busbar.

Description

Technical Field

[0001] This invention relates to the field of insulating busbar technology, specifically to a processing technology for a fire-resistant shielded insulating busbar. Background Technology

[0002] Fire-resistant insulated busbars are conductor components used in power distribution systems to transmit large currents. Their insulation layer must maintain electrical insulation performance for a certain period under fire conditions to ensure continuous power supply to critical load lines such as fire-fighting equipment and emergency lighting. Existing fire-resistant insulated busbars typically use mica tape as the fire-resistant insulation layer. The mica tape is wrapped around the outer surface of the busbar conductor through a wrapping or longitudinal wrapping process, and then an outer protective layer is applied to the outside of the mica tape through an extrusion process, ultimately forming a busbar product with fire-resistant insulation properties. In the conductor pretreatment process, existing technologies generally use a single-sided grinding method to remove the oxide layer on the surface of the busbar conductor; that is, the grinding roller applies grinding force only from one side of the conductor.

[0003] However, when the above-mentioned single-sided grinding method applies grinding force to the busbar conductor, the conductor lacks counter-support under the force on one side, and the conductor undergoes bending deformation along the grinding direction. For rectangular busbar conductors with a large cross-sectional width and thickness, the above-mentioned bending deformation is particularly obvious. At best, it affects the bonding accuracy between the mica tape and the outer surface of the conductor in the subsequent longitudinal wrapping process. At worst, it causes permanent plastic deformation of the busbar conductor in the grinding process, resulting in the flatness of the finished product exceeding the tolerance and failing to meet the installation requirements, thus increasing the scrap rate and production costs. Summary of the Invention

[0004] Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a processing technology for fire-resistant shielded insulating busbars. This technology solves the problem that the existing single-sided grinding method, due to the lack of opposing support, causes the busbar conductors to bend and deform, affecting the bonding accuracy of subsequent mica tape wrapping, and in severe cases, causing the finished product to have excessive flatness and fail to meet installation requirements.

[0005] Technical solution To achieve the above objectives, the present invention provides the following technical solution: A processing technology for a fire-resistant shielded insulating busbar includes the following steps: Step 1, conductor pretreatment: The outer surface of the busbar conductor is polished against each other using grinding rollers of a surface treatment machine to remove the oxide layer on the outer surface; Step 2, mica tape fixed-length longitudinal wrapping forming: The gradual inner cavity of the fixed-length forming mold of the longitudinal wrapping forming machine forces the single-layer fire-resistant ceramic-clad mica tape to undergo a gradual inward bending deformation, wrapping the single-layer fire-resistant ceramic-clad mica tape over the outer surface of the busbar conductor; wherein, the inner cross-sectional dimensions of the gradual inner cavity of the fixed-length forming mold are adapted to the outer cross-sectional dimensions of the busbar conductor, so that the single-layer fire-resistant ceramic-clad mica tape is tightly attached to the outer surface of the busbar conductor; the thickness of the single-layer fire-resistant ceramic-clad mica tape is 0.10 mm to 0.25 mm, and the density is 1.3. g / cm³ to 1.5 g / cm³; the longitudinal wrapping speed is 15 m / min to 60 m / min; Step 3, extrusion coating of the outer protective layer: the outer protective material is extruded and coated onto the outer surface of the single-layer refractory ceramicized mica tape through the extrusion die of the extruder to form an outer protective extruded layer. The outer protective material is low-smoke halogen-free polyolefin, cross-linked polyethylene, or silicone rubber, and the thickness of the outer protective extruded layer is 0.5 mm to 1.5 mm; Step 4, cooling and shaping: cooling medium is sprayed onto the outer surface of the outer protective extruded layer through the spray nozzles of the cooling water tank to solidify and shape the outer protective extruded layer; Step 5, finished product inspection and cutting: online insulation testing is performed by contacting the surface of the outer protective extruded layer with the electrode contacts of the withstand voltage tester, and the cooled and shaped busbar is cut to a fixed length by the shearing blade of the cutting machine.

[0006] Preferably, the longitudinal packaging forming machine further includes a main control system, a feeding motor, and a traction motor. The main control system establishes a speed coordination control relationship between the feeding speed of the feeding motor and the traction speed of the traction motor, and controls the operation of the feeding motor and the traction motor.

[0007] Preferably, step two is replaced by a wrapping process, specifically: the rotating flywheel of the wrapping machine drives the single-layer refractory ceramicized mica tape to move in a circular motion around the axis of the busbar conductor, and the single-layer refractory ceramicized mica tape is spirally wrapped around the outer surface of the busbar conductor. The rotation speed of the rotating flywheel and the axial movement speed of the busbar conductor are controlled to maintain a constant linkage relationship, so that the wrapping overlap rate of the single-layer refractory ceramicized mica tape is maintained at 15% to 30%.

[0008] Preferably, in step two, the aluminum-plastic shielding layer is first hot-pressed onto one side surface of the single-layer refractory ceramicized mica tape using the pressure rollers of a composite laminator to form a shielding composite structure, and then the shielding composite structure is wrapped around the outer surface of the busbar conductor.

[0009] Preferably, the busbar conductor is a flexible copper foil. In step two, pre-impregnated adhesive is first applied to the surface of the single-layer refractory ceramicized mica tape using the coating roller of the impregnation machine. Then, the flexible copper foil and the pre-impregnated single-layer refractory ceramicized mica tape are heated and pressed together by the heating plate of the flatbed hot press, so that the flexible copper foil and the single-layer refractory ceramicized mica tape are hot-pressed into one piece.

[0010] Preferably, between step two and step three, a graphite thermal conductive layer is wrapped around the outer surface of the busbar conductor that has been coated with a single layer of refractory ceramicized mica tape using a coating tooling of a thermal conductive layer coating machine, so that the graphite thermal conductive layer is sandwiched between the single layer of refractory ceramicized mica tape and the outer protective extruded layer.

[0011] Preferably, step two is replaced by a 3D molding and coating process, specifically: the irregular cross-section busbar conductor and the single-layer refractory ceramicized mica tape are placed between the upper and lower molds of the molding press. By closing the mold and applying pressure, the inner dimensions of the cavity formed after the upper and lower molds are closed are adapted to the outer dimensions of the irregular cross-section busbar conductor after the single-layer refractory ceramicized mica tape is coated, which forces the single-layer refractory ceramicized mica tape to deform and adhere to the surface of the irregular cross-section busbar conductor.

[0012] Preferably, the busbar conductor is made of high-conductivity T2 copper or 6061 aluminum alloy, and its cross-sectional shape is rectangular, rounded rectangular or other irregular cross-section; before step one, the method further includes: processing the conductor material to a cross-sectional size suitable for a rated current carrying range of 100A to 5000A and a rated voltage range of DC1000V to DC3000V by using the drawing die of a drawing machine or the rolls of a rolling mill.

[0013] Preferably, in step two, a pair of opposing clamping rollers are provided at the exit end of the fixed-length forming mold. The opposing clamping rollers clamp and compress the longitudinally wrapped busbar conductor in opposite directions. The gap between the opposing clamping rollers is adapted to the total composite thickness of the busbar conductor and the single-layer refractory ceramicized mica tape, so as to constrain the single-layer refractory ceramicized mica tape to be tightly attached to the outer surface of the busbar conductor.

[0014] Preferably, the longitudinal packaging forming machine and the extruder are aligned and arranged along the same baseline. The outlet end of the longitudinal packaging forming machine is connected to the inlet end of the extruder through a guide roller. The longitudinal packaging forming machine and the extruder are controlled to run synchronously so that the longitudinally packaged busbar is directly conveyed to the inlet end of the extruder. There is no drying process between the longitudinal packaging forming and the extrusion.

[0015] Beneficial effects Compared with the prior art, the present invention provides a processing technology for fire-resistant shielded insulating busbars, which has the following beneficial effects: 1. The processing technology of this fire-resistant shielded insulating busbar utilizes a double-sided grinding roller counteracting setting to cancel out the grinding forces, preventing the busbar conductor from bending and deforming under unilateral force. At the same time, it removes the oxide layer on the conductor surface, reduces the interfacial contact thermal resistance, and prevents delamination between the mica tape and the conductor due to the difference in thermal expansion coefficients under high-temperature conditions, thereby improving the insulation reliability and fire resistance stability of the busbar.

[0016] 2. The processing technology of this fire-resistant shielded insulating busbar utilizes a gradually changing inner cavity fixed-length forming mold and a pressure clamping roller in synergy. This causes the single-layer fire-resistant ceramic armor mica tape to bend gradually under the continuous constraint of the inner wall of the mold during axial movement, avoiding local stress concentration that could lead to brittle cracking of the mica tape. Furthermore, the pressure clamping roller suppresses the elastic rebound of the mica tape after it leaves the mold, ensuring that the mica tape remains tightly attached to the outer surface of the busbar conductor before entering the extrusion process, thus improving the consistency of the coating and bonding quality.

[0017] 3. The processing technology of this fire-resistant shielded insulating busbar utilizes a production line setup where the longitudinal wrapping forming machine and the extruder are aligned on the same baseline and there is no drying process in between. This allows the conductor of the longitudinally wrapped busbar to be directly transported to the inlet end of the extruder via the guide rollers, eliminating the equipment space and heating energy required for the drying process, shortening the total length of the production line, and realizing continuous synchronous operation of longitudinal wrapping forming and extrusion coating, thereby improving production efficiency. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the processing technology of the present invention; Detailed Implementation

[0019] 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.

[0020] Please see Figure 1 A processing technology for a fire-resistant shielded insulating busbar includes the following steps: Step 1, Conductor pretreatment: The outer surface of the busbar conductor is polished by the grinding rollers of the surface treatment machine to remove the oxide layer. The counter-grinding uses double grinding rollers rotating in opposite directions to act synchronously on the upper and lower surfaces of the busbar conductor, so that the grinding forces cancel each other out and prevent the busbar conductor from bending and deforming under unilateral force. The purpose of removing the oxide layer is to eliminate the high resistivity copper oxide or aluminum oxide film on the conductor surface, so that the subsequent mica tape can directly contact the conductor metal body, reduce the interfacial contact thermal resistance, and prevent the oxide layer from delaminating between the mica tape and the conductor due to the difference in thermal expansion coefficients under high temperature conditions. Step 2, Longitudinal Wrapping of Mica Tape: The gradually changing inner cavity of the long-length forming mold of the longitudinal wrapping machine forces the single-layer refractory ceramic-clad mica tape to undergo a gradual inward bending deformation, wrapping the single-layer refractory ceramic-clad mica tape around the outer surface of the busbar conductor. Along the axial direction of the busbar conductor, the cross-sectional shape of the gradually changing inner cavity gradually transitions from an open U-shape or C-shape to a closed shape that matches the outer contour of the busbar conductor. This ensures that the mica tape is continuously constrained by the inner wall of the mold during movement, gradually bending rather than suddenly bending at a single point, thus avoiding localized stress on the mica tape. Concentration leads to brittle fracture; when heated to 750℃ to 1000℃, the inorganic ceramic components of the single-layer refractory ceramic-clad mica tape undergo a sintering reaction, forming a continuous and dense ceramic-clad thermal insulation protective shell, enabling the busbar conductor to maintain its insulation performance under fire conditions and meet the fire resistance requirements for continuous power supply; the inner cross-sectional dimensions of the gradually changing cavity of the fixed-length forming mold are adapted to the outer cross-sectional dimensions of the busbar conductor, so that the single-layer refractory ceramic-clad mica tape is tightly attached to the outer surface of the busbar conductor; the thickness of the single-layer refractory ceramic-clad mica tape is 0.1 mm. The thickness ranges from 0 mm to 0.25 mm, with a density of 1.3 g / cm³ to 1.5 g / cm³. When the thickness is less than 0.10 mm, the mechanical strength of the mica tape is insufficient, making it prone to tearing during longitudinal bending. When the thickness is greater than 0.25 mm, the bending rigidity of the mica tape is too high, making it difficult to conform to the corners of the rectangular busbar conductors within the gradient inner cavity, resulting in gaps at the four corners. When the density is less than 1.3 g / cm³, the internal porosity of the mica tape is too high, the ceramicized components are unevenly distributed, and the ceramic shell formed after high-temperature sintering has localized defects. When the density is greater than 1... At a concentration of 5 g / cm³, the flexibility of the mica tape decreases, and the bending resistance during longitudinal wrapping increases. The longitudinal wrapping speed is between 15 m / min and 60 m / min. When the longitudinal wrapping speed is below 15 m / min, the production efficiency is low, and the matching window between the screw speed and extrusion volume of the extruder narrows, which is not conducive to the synchronous coordination between the extrusion process and the longitudinal wrapping process in step three. When the longitudinal wrapping speed is above 60 m / min, the residence time of the mica tape in the gradient inner cavity is shortened, and the bending deformation does not have enough time to fully unfold, resulting in the mica tape springing up and curling at the mold exit end, which affects the wrapping and bonding quality. Step 3, Extrusion Coating of the Outer Protective Layer: The outer protective material is extruded and coated onto the outer surface of the single-layer refractory ceramicized mica tape using the extrusion die of an extruder, forming an outer protective extruded layer. The outer protective material is low-smoke halogen-free polyolefin, cross-linked polyethylene, or silicone rubber, and the thickness of the outer protective extruded layer is 0.5mm to 1.5mm. The extrusion die uses a special-shaped die that matches the outer contour of the busbar conductor cross-section, so that the outer protective material is uniformly coated onto the outer surface of the mica tape in a molten state, forming an outer protective extruded layer of uniform thickness. Low-smoke halogen-free polyolefin is suitable for buildings and public places with strict requirements on smoke toxicity. Cross-linked polyethylene has a higher upper limit of long-term operating temperature and is suitable for working conditions with high requirements for thermal stability. Silicone rubber is suitable for occasions that need to operate for a long time in ambient temperatures above 150℃. When the thickness of the outer protective extruded layer is less than 0.5mm, the mechanical protection capability is insufficient, and it is easily damaged by friction or collision during installation. When the thickness is greater than 1.5mm, the outer dimensions of the busbar increase, resulting in a decrease in the space utilization of the installation slot. Step 4, Cooling and Shaping: Cooling medium is sprayed onto the outer surface of the outer protective extruded layer through the spray nozzles of the cooling water tank to solidify and shape the outer protective extruded layer. The spraying cooling medium is room temperature circulating water. The spraying method ensures that the cooling medium acts evenly on the entire outer surface of the outer protective extruded layer in the form of atomization or jet, avoiding warping deformation or residual stress caused by uneven local temperature during the cooling process of the busbar. The cooling water tank is set as a gradient cooling section along the running direction of the busbar, so that the cooling process of the outer protective extruded layer from the extrusion temperature to room temperature is completed in stages, preventing surface cracking caused by excessive difference in shrinkage rate between the inside and outside of the outer protective extruded layer due to sudden cooling. Step 5, Finished Product Inspection and Cutting: Online insulation testing is performed by contacting the surface of the outer protective extruded layer with the electrode contacts of the withstand voltage tester. The cooled and shaped busbars are then cut to a fixed length using the shearing blades of the cutting machine. The online insulation testing utilizes the spark detection principle, applying a high-frequency, high-voltage signal to the outer surface of the outer protective extruded layer. When defects such as pinholes, cracks, or insufficient thickness exist in the outer protective extruded layer, the insulation breakdown voltage is lower than the test voltage, triggering an alarm signal on the withstand voltage tester. This achieves meter-by-meter full inspection of the integrity of the outer protective extruded layer without the need for offline sampling. The fixed-length cutting uses an encoder to count the cumulative running length of the busbars in real time. When the count reaches the set length, the cutting machine is triggered, ensuring the consistency of the finished product length.

[0021] The longitudinal wrapping forming machine also includes a main control system, a feeding motor, and a traction motor. The main control system establishes a speed coordination control relationship between the feeding motor's conveying speed and the traction motor's traction speed, controlling the actions of the feeding motor and traction motor to keep the ratio of the conveying speed of the single-layer refractory ceramic-clad mica tape to the running speed of the busbar conductor constant at 1. A constant ratio of 1 means that the linear velocity of the mica tape and the linear velocity of the busbar conductor remain strictly equal. When the conveying speed is lower than the traction speed, the mica tape is subjected to axial tensile tension during longitudinal wrapping, resulting in a narrowing of the mica tape's width and an increase in its thickness, affecting the uniformity of the wrapping width. When the conveying speed is higher than the traction speed, the mica tape accumulates at the entrance end of the fixed-length forming mold, forming wrinkles, causing the mica tape to fold rather than bend smoothly within the mold cavity. The main control system collects the speed feedback signals of the feeding motor and traction motor in real time and performs closed-loop adjustment of their speeds according to the speed coordination control relationship to ensure that the ratio remains constant throughout the entire longitudinal wrapping process.

[0022] Step two is replaced by a wrapping process, specifically: the rotating flywheel of the wrapping machine drives the single-layer refractory ceramicized mica tape to make a circular motion around the axis of the busbar conductor, and the single-layer refractory ceramicized mica tape is spirally wrapped around the outer surface of the busbar conductor. The rotation speed of the rotating flywheel and the axial movement speed of the busbar conductor are controlled to maintain a constant linkage relationship, so that the wrapping overlap rate of the single-layer refractory ceramicized mica tape is maintained between 15% and 30%. The spiral wrapping method is suitable for busbar conductors with a circular or near-circular cross-section. The wrapping pitch is determined by the rotational speed of the rotating flywheel and the axial movement speed of the busbar conductor. When the wrapping overlap rate is less than 15%, the overlap width between adjacent wrapping loops is insufficient, and the overlap edge is prone to cracking and separation when the busbar conductor bends, forming a weak insulation area. When the wrapping overlap rate is greater than 30%, the effective utilization rate of the mica tape decreases, and the local thickness of the multi-layer superimposed area increases, causing periodic fluctuations in the outer dimensions of the subsequent extruded layer. The linkage relationship ensures that when the axial movement speed of the busbar conductor changes, the rotational speed of the rotating flywheel is adjusted synchronously and proportionally, so that the wrapping pitch and overlap rate remain constant in any speed range.

[0023] In step two, the aluminum-plastic shielding layer is first hot-pressed onto one side of a single-layer refractory ceramicized mica tape using the pressure rollers of a composite laminator, forming a shielding composite structure. This composite structure is then wrapped around the outer surface of the busbar conductor. The aluminum-plastic shielding layer is composed of an aluminum foil layer and a polyester film layer, with the aluminum foil layer facing the busbar conductor to form a continuous, low-impedance conductive shielding surface, suppressing electromagnetic interference radiated outwards from the busbar during operation. The aluminum-plastic shielding layer is pre-hot-pressed onto one side of the mica tape, making the shielding layer and mica tape an integrated composite structure. During subsequent longitudinal wrapping, both are bent together with the mica tape, preventing wrinkles caused by insufficient rigidity when the aluminum-plastic shielding layer is wrapped separately, ensuring the shielding layer remains continuous and unbroken at all parts of the busbar cross-section. The heating temperature and pressing pressure of the pressure rollers are set according to the softening temperature of the adhesive used in the aluminum-plastic shielding layer, ensuring the peel strength between the aluminum-plastic shielding layer and the mica tape meets the requirements of the subsequent bending process.

[0024] The busbar conductor is a flexible copper foil. In step two, the pre-impregnated adhesive is first applied to the surface of the single-layer refractory ceramicized mica tape by the coating roller of the impregnation machine. Then, the flexible copper foil and the single-layer refractory ceramicized mica tape coated with pre-impregnated adhesive are heated and pressed by the heating plate of the flat hot press, so that the flexible copper foil and the single-layer refractory ceramicized mica tape are hot-pressed into one piece. Flexible copper foil is composed of multiple layers of copper foil, exhibiting high bending flexibility in the bending direction, making it suitable for connection applications requiring multiple bending installations. The pre-impregnated adhesive is solid or semi-solid at room temperature. After coating, the mica tape can be stacked at room temperature without sticking. During heating and pressurization, the pre-impregnated adhesive softens and spreads evenly at the interface between the copper foil and the mica tape. After curing, it forms a continuous adhesive layer, firmly bonding the flexible copper foil and the mica tape together. The heating plate of the flatbed hot press provides both heat and pressure, ensuring that interface air bubbles are expelled during the curing process of the pre-impregnated adhesive, preventing voids in the cured adhesive layer that could lead to weak points in the insulation. After hot pressing and integral molding, there is no relative sliding between the mica tape and the flexible copper foil. During subsequent bending and use, the two deform together, preventing delamination between the insulation layer and the conductor.

[0025] Between step two and step three, the graphite thermal conductive layer is wrapped around the outer surface of the busbar conductor that has been coated with a single layer of refractory ceramicized mica tape using the coating tooling of the thermal conductive layer coating machine, so that the graphite thermal conductive layer is sandwiched between the single layer of refractory ceramicized mica tape and the outer protective extruded layer. The graphite thermal conductive layer is made of flexible expanded graphite sheets with an in-plane thermal conductivity of 100 W / (m·K) to 700 W / (m·K), which is much higher than that of the mica tape and the outer protective extruded layer. It can rapidly diffuse the Joule heat generated by the busbar conductor during current carrying along the axial and circumferential directions of the busbar, reducing the local hot spot temperature of the busbar conductor. The graphite thermal conductive layer is sandwiched between the mica tape and the outer protective extruded layer. On the one hand, the covering pressure of the outer protective extruded layer makes the graphite thermal conductive layer and the outer surface of the mica tape fit tightly together, reducing the interfacial thermal resistance. On the other hand, the outer protective extruded layer provides mechanical protection for the graphite thermal conductive layer, preventing the graphite sheets from peeling off due to friction or collision during installation. The wrapping fixture is designed according to the cross-sectional shape of the busbar conductor to ensure that the graphite thermal conductive layer fits evenly during the wrapping process without wrinkles or gaps.

[0026] Step 2 is replaced by a 3D molding and coating process, specifically: the irregular cross-section busbar conductor and the single-layer refractory ceramicized mica tape are placed between the upper and lower molds of the forming press. By closing the mold and applying pressure, the inner contour of the cavity formed after the upper and lower molds are closed is adapted to the outer contour of the irregular cross-section busbar conductor after the single-layer refractory ceramicized mica tape is coated, which forces the single-layer refractory ceramicized mica tape to deform and adhere to the surface of the irregular cross-section busbar conductor. 3D molding and covering process is suitable for irregular cross-section busbar conductors with complex features such as bosses, grooves, arc surfaces, or polygonal edges. Such cross-sections cannot be uniformly fitted by the gradient inner cavity of the longitudinal wrapping molding machine. The mica tape is pre-cut into a flat blank corresponding to the unfolded area of ​​the irregular cross-section busbar conductor. After being placed between the upper and lower molds, the mold is closed and pressure is applied, causing the mica tape to deform simultaneously in three dimensions and fit against the entire outer surface of the busbar conductor. The inner contour dimensions of the mold cavity are matched with the outer contour dimensions of the busbar conductor after being covered with mica tape, ensuring that the mica tape is subjected to uniform constraint pressure from all directions of the mold cavity after mold closing, so that there is no local gap between the mica tape and the busbar conductor. The mold closing pressure must be set to ensure that the mica tape does not become brittle while deforming. The specific pressure value is determined according to the thickness and density of the mica tape and the radius of curvature of the busbar conductor cross-section.

[0027] The busbar conductor uses high-conductivity T2 copper conductor or 6061 aluminum alloy conductor, with a rectangular, rounded rectangular, or other irregular cross-sectional shape. Before step one, the process includes: processing the conductor material to a cross-sectional size suitable for a rated current carrying range of 100A to 5000A and a rated voltage range of DC1000V to DC3000V using a drawing die or rolling mill. The conductivity of the T2 copper conductor is not less than 97% IACS, and the conductivity of the 6061 aluminum alloy conductor is not less than 45% IACS. Under the same cross-sectional area, the current carrying capacity of the T2 copper conductor is higher than that of the 6061 aluminum alloy conductor, but the 6061 aluminum alloy conductor is lighter than the T2 copper conductor, making it suitable for installation applications with strict weight restrictions on the busbar. The rectangular cross-section busbar conductor has a regular, flat outer surface on all four sides, suitable for achieving uniform longitudinal wrapping in the gradually changing inner cavity of the fixed-length forming die. The rounded rectangular cross-section is based on the rectangular cross-section with the four corners... The rounded transition reduces the electric field concentration effect at the corners and also reduces the stress concentration when the mica tape is bent and wrapped around the corners; the drawing process applies axial tensile force to the conductor through the tapered die, gradually reducing the conductor cross-sectional area to the target size, which is suitable for processing conductors with smaller cross-sectional areas; the rolling process applies radial compressive force to the conductor through one or more pairs of rolls, which is suitable for processing conductors with larger cross-sectional areas; the rated current carrying range of 100A to 5000A corresponds to a conductor cross-sectional area range of approximately 10mm² to 500mm².

[0028] In step two, a pair of opposing clamping rollers are provided at the exit end of the fixed-length forming mold. The opposing clamping rollers clamp and compress the longitudinally wrapped busbar conductor in opposite directions. The gap between the opposing clamping rollers is adapted to the total composite thickness of the busbar conductor and the single-layer refractory ceramicized mica tape, so as to constrain the single-layer refractory ceramicized mica tape to adhere tightly to the outer surface of the busbar conductor. The purpose of setting the clamping rollers at the exit end of the fixed-length forming die is that, after the mica tape leaves the constraint of the gradient inner cavity, it tends to flip outward due to its own elastic recovery force. This is especially true when the width-to-thickness ratio of the busbar conductor cross-section is large, and the rebound at the overlap seam on both sides after the mica tape is wrapped is particularly obvious. The clamping rollers apply opposing clamping forces to both sides of the busbar conductor in the thickness direction, so that the overlap seam of the mica tape is subjected to continuous closing pressure, forming a transition section between the mica tape and the outer protective extruded layer, keeping the mica tape in a bonded state until it enters the extrusion die of the extruder. The gap between the clamping rollers is equal to the sum of the thickness of the busbar conductor and the total thickness of the double-layer composite mica tape. If the gap is too large, the clamping force will be insufficient; if the gap is too small, the mica tape will be over-compressed, resulting in damage to the internal structure of the mica tape.

[0029] The longitudinal packaging forming machine and the extruder are aligned and arranged on the same baseline. The outlet end of the longitudinal packaging forming machine and the inlet end of the extruder are connected through the guide roller. The longitudinal packaging forming machine and the extruder are controlled to run synchronously so that the mother busbar after longitudinal packaging is directly conveyed to the inlet end of the extruder. There is no drying process between longitudinal packaging forming and extrusion. Alignment along the same baseline means that the outlet center axis of the longitudinal wrapping forming machine and the inlet center axis of the extruder are collinear. This ensures that the busbar conductor does not shift or twist during the transition from the longitudinal wrapping forming machine to the extruder, preventing the longitudinally wrapped mica tape from loosening or misaligning due to lateral shear force in the transition section. The guide rollers support and guide the busbar conductor, reducing the sagging and deflection caused by the suspended span between the outlet end of the longitudinal wrapping forming machine and the inlet end of the extruder. The design without a drying process is based on the fact that the single-layer refractory ceramic-coated mica tape itself does not contain liquid adhesives that require drying and curing. After longitudinal wrapping, the mica tape and the busbar conductor are kept in a close fit by the mold constraint force and the clamping force of the pressure clamping rollers, allowing it to directly enter the extruder. The covering pressure of the outer protective extrusion layer permanently fixes the mica tape. Eliminating the drying process shortens the total length of the production line and eliminates the heating energy consumption required by the drying oven.

[0030] It should be noted that, in this document, relational terms such as "first" and "second" are used only 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, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

Claims

1. A processing technology for a fire-resistant shielded insulating busbar, characterized in that, Includes the following steps: Step 1, conductor pretreatment: The outer surface of the busbar conductor is polished by the grinding rollers of the surface treatment machine to remove the oxide layer on the outer surface; Step 2, Longitudinal Wrapping of Mica Tape: The gradually changing inner cavity of the longitudinal wrapping machine's forming mold forces the single-layer refractory ceramic-clad mica tape to undergo a gradual inward bending deformation, wrapping the single-layer refractory ceramic-clad mica tape over the outer surface of the busbar conductor. The inner cross-sectional dimensions of the gradually changing inner cavity of the forming mold are adapted to the outer cross-sectional dimensions of the busbar conductor, ensuring the single-layer refractory ceramic-clad mica tape adheres tightly to the outer surface of the busbar conductor. The thickness of the single-layer refractory ceramic-clad mica tape is 0.10 mm to 0.25 mm, and its density is 1.3 g / cm³ to 1.5 g / cm³. The longitudinal wrapping speed is 15 m / min to 60 m / min. Step 3, extrusion coating of outer protective layer: The outer protective material is extruded and coated onto the outer surface of the single-layer refractory ceramicized mica tape through the extrusion die of the extruder to form an outer protective extruded layer. The outer protective material is low smoke halogen-free polyolefin, cross-linked polyethylene or silicone rubber, and the thickness of the outer protective extruded layer is 0.5 mm to 1.5 mm. Step 4, Cooling and Shaping: Cooling medium is sprayed onto the outer surface of the outer protective extruded layer through the spray nozzles of the cooling water tank to solidify and shape the outer protective extruded layer. Step 5, Finished Product Inspection and Cutting: Online insulation testing is performed by contacting the surface of the outer protective extruded layer with the electrode contacts of the withstand voltage tester, and the cooled and shaped busbar is cut to a fixed length by the shearing blade of the cutting machine.

2. The processing technology of a fire-resistant shielded insulating busbar according to claim 1, characterized in that, The longitudinal packaging forming machine also includes a main control system, a feeding motor, and a traction motor. The main control system establishes a speed coordination control relationship between the feeding speed of the feeding motor and the traction speed of the traction motor, and controls the operation of the feeding motor and the traction motor.

3. The processing technology of a fire-resistant shielded insulating busbar according to claim 1, characterized in that, Step two is replaced by a wrapping process, specifically: the rotating flywheel of the wrapping machine drives the single-layer refractory ceramicized mica tape to make a circular motion around the axis of the busbar conductor, and the single-layer refractory ceramicized mica tape is spirally wrapped around the outer surface of the busbar conductor. The rotation speed of the rotating flywheel and the axial movement speed of the busbar conductor are controlled to maintain a constant linkage relationship, so that the wrapping overlap rate of the single-layer refractory ceramicized mica tape is maintained between 15% and 30%.

4. The processing technology of a fire-resistant shielded insulating busbar according to claim 1, characterized in that, In step two, the aluminum-plastic shielding layer is first hot-pressed onto one side surface of the single-layer refractory ceramicized mica tape using the pressure rollers of the composite laminator to form a shielding composite structure. Then, the shielding composite structure is wrapped around the outer surface of the busbar conductor.

5. The processing technology of a fire-resistant shielded insulating busbar according to claim 1, characterized in that, The busbar conductor is a flexible copper foil. In step two, the pre-impregnated adhesive is first applied to the surface of the single-layer refractory ceramicized mica tape by the coating roller of the impregnation machine. Then, the flexible copper foil and the single-layer refractory ceramicized mica tape coated with pre-impregnated adhesive are heated and pressed by the heating plate of the flat hot press, so that the flexible copper foil and the single-layer refractory ceramicized mica tape are hot-pressed into one piece.

6. The processing technology of a fire-resistant shielded insulating busbar according to claim 1, characterized in that, Between step two and step three, the graphite thermal conductive layer is wrapped around the outer surface of the busbar conductor that has been coated with a single layer of refractory ceramicized mica tape using the coating tooling of the thermal conductive layer coating machine, so that the graphite thermal conductive layer is sandwiched between the single layer of refractory ceramicized mica tape and the outer protective extruded layer.

7. The processing technology of a fire-resistant shielded insulating busbar according to claim 1, characterized in that, Step two is replaced by a 3D molding and coating process, specifically: the irregular cross-section busbar conductor and the single-layer refractory ceramicized mica tape are placed between the upper and lower molds of the molding press. By closing the mold and applying pressure, the inner dimensions of the cavity formed after the upper and lower molds are closed are adapted to the outer dimensions of the irregular cross-section busbar conductor after the single-layer refractory ceramicized mica tape is coated, which forces the single-layer refractory ceramicized mica tape to deform and adhere to the surface of the irregular cross-section busbar conductor.

8. The processing technology of a fire-resistant shielded insulating busbar according to claim 1, characterized in that, The busbar conductor is made of high-conductivity T2 copper or 6061 aluminum alloy, and its cross-sectional shape is rectangular, rounded rectangular or other irregular cross-section; before step one, the method further includes: processing the conductor material to a cross-sectional size suitable for a rated current carrying range of 100A to 5000A and a rated voltage range of DC1000V to DC3000V by using the drawing die of a drawing machine or the rolls of a rolling mill.

9. The processing technology of a fire-resistant shielded insulating busbar according to claim 1, characterized in that, In step two, a pair of opposing clamping rollers are provided at the exit end of the fixed-length forming mold. The opposing clamping rollers clamp and compress the longitudinally wrapped busbar conductor in opposite directions. The gap between the opposing clamping rollers is adapted to the total composite thickness of the busbar conductor and the single-layer refractory ceramicized mica tape, so as to constrain the single-layer refractory ceramicized mica tape to be tightly attached to the outer surface of the busbar conductor.

10. The processing technology of a fire-resistant shielded insulating busbar according to claim 1, characterized in that, The longitudinal packaging forming machine and the extruder are aligned and arranged along the same baseline. The outlet end of the longitudinal packaging forming machine is connected to the inlet end of the extruder through a guide roller. The longitudinal packaging forming machine and the extruder are controlled to run synchronously so that the longitudinally packaged busbar is directly transported to the inlet end of the extruder. There is no drying process between the longitudinal packaging forming and the extrusion.

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