Preparation method of steel-based alternating current composite conductor

Abstract

The invention discloses a preparation method of a steel-based alternating-current composite conductor, the structure of the steel-based alternating-current composite conductor is as follows from outside to inside: the first layer is a copper coating layer, the second layer is an aluminum coating layer, and the innermost layer is a steel core, and the steel-based alternating-current composite conductor has the beneficial effects that a composite material with relatively high strength, good plasticity and conductivity is obtained, and the required performance can be obtained through composite preparation, deformation and aging processes; the copper-aluminum alloy material has excellent conductivity of copper, also has the characteristic of light weight of aluminum, has high strength, high modulus and low relaxation of steel and good conductivity and atmospheric corrosion resistance of copper, achieves the purposes of excellent performance and low cost, and can be widely applied to the fields of power transmission, electronic equipment, communication systems, new energy automobiles, photovoltaic power generation and the like.

Description

Technical Field

[0001] This invention belongs to the category of composite conductors, and relates to the field of AC composite conductors, and more particularly to a method for preparing a steel-based AC composite conductor. Background Technology

[0002] Copper conductors possess excellent electrical conductivity and are widely used in power transmission, electronic equipment, communication systems, new energy vehicles, and photovoltaic power generation. They are also widely used in refractory layers, insulation layers, sheaths, and filler materials, playing a dominant role in ultra-high voltage projects. Due to the increasing imbalance between copper supply and demand and persistently high copper prices, copper has become a crucial strategic resource second only to oil, forcing companies and researchers to seek new, low-cost conductor materials to replace pure copper. Furthermore, steel possesses high mechanical strength, strong load-bearing capacity, making it more suitable for long-span power transmission projects, and is also inexpensive. Since the current density of alternating current is highest near the conductor surface and decreases exponentially with increasing conductor depth, using steel as the conductor base material and aluminum and copper as the conductive layers can achieve a combination of excellent conductivity (copper), lightweight properties (aluminum), and high mechanical strength and load-bearing capacity (steel), thus achieving superior performance at a low cost. Summary of the Invention

[0003] This invention discloses a method for preparing a steel-based AC composite conductor to overcome the shortcomings of the prior art.

[0004] The technical solution provided by this invention is: a steel-based AC composite conductor, from the outside to the inside: the first layer is a copper cladding layer—the second layer is an aluminum cladding layer—the innermost layer is a steel core; The copper content of the copper cladding layer is ≥99.95%; The aluminum cladding layer has the following chemical composition (mass percentage): Fe: 0.5%–1.5%, Cu: 0.1%–0.5%, with the balance being Al; The steel core has the following chemical composition (mass percentage): Mn: 1.4–2.0%, and Mn / Si > 60; The copper cladding layer accounts for 15% to 30% of the total volume of the composite conductor; The aluminum cladding layer accounts for 20% to 40% of the total volume of the composite conductor; The covering layer is coaxially disposed with the core material; As mentioned above; Step 1, Aluminum plating of steel core: The steel core wire rod is laid out and the ends are welded to achieve uninterrupted operation of the production line — the surface oil and oxide scale are thoroughly removed — it is immersed in an environmentally friendly flux solution — it is put into a reduction annealing furnace, heated and completely dried in a protective atmosphere — it is immersed in an aluminum-silicon alloy molten pool at 680~750℃ to form an aluminum-plated steel core. Step 2, Aluminum cladding layer processing: The processed aluminized steel core and aluminum strip are simultaneously fed into a set of forming molds. The aluminum strip is gradually bent into a "C" shape in the continuous roll forming mold, and then wrapped around the aluminized steel core that is moving at a uniform speed, finally forming a closed "O" shaped tube that completely encloses the aluminized steel core. The aluminized steel core wrapped by the aluminum strip passes through a high-frequency induction coil. At the closed joint of the aluminum strip, the high-frequency current generates skin effect and proximity effect, causing the aluminum layer at the edge of the joint to be locally heated to a semi-molten state. Under the pressure of the forming roller, the molten aluminum is squeezed and fused, so that the joint is completely welded, forming a sealed aluminum tube that wraps around the steel core in a composite wire blank. The raised weld beads are removed by online scraping to make the outer diameter of the wire blank round and smooth. Subsequently, the wire blank enters the drawing machine for the first diameter reduction drawing. Through plastic deformation, the outer aluminum layer and the inner steel core undergo coordinated deformation. Step 3, intermediate heat treatment: After the initial drawing, the composite wire rod enters a continuous annealing furnace and is heated to 400~550℃ in a protective atmosphere to activate the diffusion ability of aluminum and iron atoms. Step 4, copper plating: Immerse the steel-aluminum composite wire core in a zincate solution—through a displacement reaction, a dense zinc layer is deposited on its surface—removed with nitric acid, and then subjected to a second zinc immersion to obtain a more uniform and fine zinc layer; Step 5, Copper cladding: The processed copper-plated steel-aluminum composite wire core and copper strip are simultaneously fed into a set of forming molds. The copper strip is gradually bent into a "C" shape in the continuous roller bending forming mold, and then wrapped around the copper-plated steel-aluminum composite wire core that is moving at a uniform speed, finally forming a closed "O" shaped tube that completely encloses the copper-plated steel-aluminum composite wire core. The copper-plated steel-aluminum composite wire core wrapped by the copper strip passes through a high-frequency induction coil. At the closed joint of the copper strip, the high-frequency current generates the skin effect and proximity effect, causing the copper layer at the edge of the joint to be locally heated to a semi-molten state. Under the pressure of the forming roller, the molten copper is squeezed and fused, so that the joint is completely welded, forming a sealed copper tube that encloses the steel-core aluminum composite wire blank. The raised weld beads are removed by online scraping to make the outer diameter of the wire blank round and smooth. Subsequently, the wire blank enters the drawing machine for a second diameter reduction drawing. Through plastic deformation, the outer copper layer and the middle aluminum layer undergo coordinated deformation. Step 6, drawing diameter reduction and strengthening: cold drawing is performed through multiple drawing dies to reduce the diameter to the target size, further densifying the composite layer, making the interface bonding stronger, and improving the tensile strength of the material. Step 7, Heat treatment: Continuous annealing is performed according to product requirements to form a more stable metallurgical layer; Step 8, finishing and winding: The finished product is sized, polished, and finally wound up.

[0005] The environmentally friendly plating flux includes, but is not limited to, potassium fluorozirconate; The protective atmosphere comprises one of N2, H2 and NO2, or a mixture thereof; The silicon content in the aluminum-silicon alloy is 5% to 11%.

[0006] The beneficial effects of this invention are: Composite materials with high strength, good plasticity and conductivity, and tensile strength greater than 250MPa, can be obtained through composite preparation-deformation-aging process to achieve the desired properties. This process combines the excellent conductivity of copper with the light weight of aluminum, and also incorporates the high strength, high modulus and low relaxation of steel with the good conductivity and atmospheric corrosion resistance of copper, thus achieving the goal of excellent performance and low cost. Attached Figure Description

[0007] Figure 1 This is a schematic diagram of the cross-sectional structure of the present invention; Figure 2 This is a flowchart of the processing steps of the present invention.

[0008] In the diagram: 1. Steel core, 2. Iron-aluminum-silicon alloy layer, 3. Aluminum cladding layer, 4. Zinc-nickel base layer, 5. Copper cladding layer. Detailed Implementation

[0009] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0010] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "positive," "negative," "vertical," "horizontal," "top," "bottom," "inner," "outer," "one side," "one end," and "one side," etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0011] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly; they can refer to mechanical connections or electrical connections; they can be direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0012] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0013] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the application. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0014] It should also be further understood that the term “and / or” as used in this specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0015] The accompanying drawings illustrate various structural schematics according to embodiments disclosed in this application. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0016] Referring to the accompanying drawings, this invention discloses a method for preparing a steel-based AC composite conductor, the structure of which, from the outside to the inside, consists of: a first layer of copper cladding, a second layer of aluminum cladding, and an innermost steel core. The copper content of the copper cladding layer is ≥99.95%; The aluminum cladding layer has the following chemical composition (mass percentage): Fe: 0.5%–1.5%, Cu: 0.1%–0.5%, with the balance being Al; The steel core has the following chemical composition (mass percentage): Mn: 1.4–2.0%, and Mn / Si > 60; The copper cladding layer accounts for 15% to 30% of the total volume of the composite conductor; The aluminum cladding layer accounts for 20% to 40% of the total volume of the composite conductor; The covering layer is coaxially disposed with the core material; As described above, the processing steps for preparing a steel-based AC composite conductor are as follows: S1, Aluminum-plated steel core: Steel core wire rods are laid out and welded at both ends to achieve uninterrupted production line operation—the surface oil and oxide scale are thoroughly removed—the metal core is immersed in an environmentally friendly flux solution to prevent secondary oxidation—it is placed in a reduction annealing furnace, heated and completely dried in a protective atmosphere—it is immersed in an aluminum-silicon alloy molten pool at 680~750℃—a gradient alloy layer is generated on the surface through high-frequency induction heating—aluminum-plated steel core is formed. Step 2, Aluminum cladding layer processing: The processed aluminized steel core and aluminum strip are simultaneously fed into a set of forming molds. The aluminum strip is gradually bent into a "C" shape in the continuous roll forming mold, and then wrapped around the aluminized steel core that is moving at a uniform speed, finally forming a closed "O" shaped tube that completely encloses the aluminized steel core. The aluminized steel core wrapped by the aluminum strip passes through a high-frequency induction coil. At the closed joint of the aluminum strip, the high-frequency current generates skin effect and proximity effect, causing the aluminum layer at the edge of the joint to be locally heated to a semi-molten state. Under the pressure of the forming roller, the molten aluminum is squeezed and fused, so that the joint is completely welded, forming a sealed aluminum tube that wraps around the steel core in a composite wire blank. The raised weld beads are removed by online scraping to make the outer diameter of the wire blank round and smooth. Subsequently, the wire blank enters the drawing machine for the first diameter reduction drawing. Through plastic deformation, the outer aluminum layer and the inner steel core undergo coordinated deformation. Step 3, Intermediate Heat Treatment: After the initial drawing, the composite wire rod enters a continuous annealing furnace and is heated to 400-550℃ in a protective atmosphere to activate the diffusion ability of aluminum and iron atoms. Under the influence of temperature, aluminum and iron atoms diffuse across the interface, forming a thin and uniform intermetallic compound layer (mainly FeAl3, Fe2Al5, etc.) at the interface. The formation of this diffusion layer signifies a strong metallurgical bond between the aluminum layer and the steel core. Heat treatment also eliminates work hardening caused by drawing and restores the plasticity of the aluminum layer. Step 4, copper plating: Immerse the steel-aluminum composite wire core in a zincate solution—through a displacement reaction, a dense zinc layer is deposited on its surface—removed with nitric acid, and then subjected to a second zinc immersion to obtain better bonding and a more uniform and fine zinc layer. Step 5, Copper cladding: The processed copper-plated steel-aluminum composite wire core and copper strip are simultaneously fed into a set of forming molds. The copper strip is gradually bent into a "C" shape in the continuous roller bending forming mold, and then wrapped around the copper-plated steel-aluminum composite wire core that is moving at a uniform speed, finally forming a closed "O" shaped tube that completely encloses the copper-plated steel-aluminum composite wire core. The copper-plated steel-aluminum composite wire core wrapped by the copper strip passes through a high-frequency induction coil. At the closed joint of the copper strip, the high-frequency current generates the skin effect and proximity effect, causing the copper layer at the edge of the joint to be locally heated to a semi-molten state. Under the pressure of the forming roller, the molten copper is squeezed and fused, so that the joint is completely welded, forming a sealed copper tube that encloses the steel-core aluminum composite wire blank. The raised weld beads are removed by online scraping to make the outer diameter of the wire blank round and smooth. Subsequently, the wire blank enters the drawing machine for a second diameter reduction drawing. Through plastic deformation, the outer copper layer and the middle aluminum layer undergo coordinated deformation. Step 6, drawing diameter reduction and strengthening: cold drawing is performed through multiple drawing dies to reduce the diameter to the target size, further densifying the composite layer, making the interface bonding stronger, and improving the tensile strength of the material. Step 7, Heat treatment: Continuous annealing is performed according to product requirements to form a more stable metallurgical layer; Step 8, finishing and winding: The finished product is sized, polished, and finally wound up.

[0017] The environmentally friendly plating flux includes, but is not limited to, potassium fluorozirconate; The protective atmosphere comprises one of N2, H2 and NO2, or a mixture thereof; The silicon content in the aluminum-silicon alloy is 5% to 11%; The nickel content in the zincate solution is 2~10 g / L.

Claims

1. A method for preparing a steel-based AC composite conductor, the structure of which, from the outside to the inside, consists of: a first layer of copper cladding, a second layer of aluminum cladding, and an innermost steel core; Its features are: The copper content of the copper cladding layer is ≥99.95%; The aluminum cladding layer has the following chemical composition (mass percentage): Fe: 0.5%–1.5%, Cu: 0.1%–0.5%, with the balance being Al; The steel core has a chemical composition (mass percentage) of Mn: 1.4–2.0%, and Mn / Si > 60. The copper cladding layer accounts for 15% to 30% of the total volume of the composite conductor; The aluminum cladding layer accounts for 20% to 40% of the total volume of the composite conductor; The covering layer is coaxially arranged with the core material.

2. As described in claim 1, characterized in that: The preparation method of a steel-based AC composite conductor has the following processing steps: S1, Aluminum-plated steel core: Steel core wire rods are laid out and welded at both ends to achieve uninterrupted production line operation—the surface oil and oxide scale are thoroughly removed—the metal core is immersed in an environmentally friendly flux solution to prevent secondary oxidation—it is placed in a reduction annealing furnace, heated and completely dried in a protective atmosphere—it is immersed in an aluminum-silicon alloy molten pool at 680~750℃—a gradient alloy layer is generated on the surface through high-frequency induction heating—aluminum-plated steel core is formed. Step 2, Aluminum cladding layer processing: The processed aluminized steel core and aluminum strip are simultaneously fed into a set of forming molds. The aluminum strip is gradually bent into a "C" shape in the continuous roll forming mold, and then wrapped around the aluminized steel core that is moving at a uniform speed, finally forming a closed "O" shaped tube that completely encloses the aluminized steel core. The aluminized steel core wrapped by the aluminum strip passes through a high-frequency induction coil. At the closed joint of the aluminum strip, the high-frequency current generates skin effect and proximity effect, causing the aluminum layer at the edge of the joint to be locally heated to a semi-molten state. Under the pressure of the forming roller, the molten aluminum is squeezed and fused, so that the joint is completely welded, forming a sealed aluminum tube that wraps around the steel core in a composite wire blank. The raised weld beads are removed by online scraping to make the outer diameter of the wire blank round and smooth. The wire blank enters the drawing machine for the first diameter reduction drawing. Through plastic deformation, the outer aluminum layer and the inner steel core undergo coordinated deformation. Step 3, intermediate heat treatment: After the initial drawing, the composite wire rod enters a continuous annealing furnace and is heated to 400~550℃ in a protective atmosphere to activate the diffusion ability of aluminum and iron atoms. Step 4, copper plating: Immerse the steel-aluminum composite wire core in a zincate solution—through a displacement reaction, a dense zinc layer is deposited on its surface—removed with nitric acid, and then subjected to a second zinc immersion to obtain better bonding and a more uniform and fine zinc layer. Step 5, Copper cladding: The processed copper-plated steel-aluminum composite wire core and copper strip are simultaneously fed into a set of forming molds. The copper strip is gradually bent into a "C" shape in the continuous roller bending forming mold, and then wrapped around the copper-plated steel-aluminum composite wire core that is moving at a uniform speed, finally forming a closed "O" shaped tube that completely encloses the copper-plated steel-aluminum composite wire core. The copper-plated steel-aluminum composite wire core wrapped by the copper strip passes through a high-frequency induction coil. At the closed joint of the copper strip, the high-frequency current generates the skin effect and proximity effect, causing the copper layer at the edge of the joint to be locally heated to a semi-molten state. Under the pressure of the forming roller, the molten copper material is squeezed and fused, so that the joint is completely welded, forming a sealed copper tube that encloses the steel-core aluminum composite wire blank. The raised weld beads are removed by online scraping to make the outer diameter of the wire blank round and smooth. The wire blank enters the drawing machine for a second diameter reduction drawing. Through plastic deformation, the outer copper layer and the middle aluminum layer undergo coordinated deformation. Step 6, drawing diameter reduction and strengthening: cold drawing is performed through multiple drawing dies to reduce the diameter to the target size, further densifying the composite layer, making the interface bonding stronger, and improving the tensile strength of the material. Step 7, Heat treatment: Continuous annealing is performed according to product requirements to form a more stable metallurgical layer; Step 8, finishing and winding: The finished product is sized, polished, and finally wound up.

3. As described in claim 2, characterized in that: A method for preparing a steel-based AC composite conductor, wherein the environmentally friendly plating flux includes, but is not limited to, potassium fluorozirconate.

4. As described in claim 2, characterized in that: A method for preparing a steel-based AC composite conductor, wherein the protective atmosphere comprises one of N2, H2 and NO2 and mixtures thereof.

5. As described in claim 2, characterized in that: A method for preparing a steel-based AC composite conductor, wherein the silicon content in the aluminum-silicon alloy is 5% to 11%.

6. As described in claim 2, characterized in that: A method for preparing a steel-based AC composite conductor, wherein the nickel content in the zincate solution is 2~10 g / L.

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