Production process of steel-cored aluminum strand

Abstract

The invention discloses a production process of a steel-cored aluminum strand, and relates to the technical field of cable production, and the production process of the steel-cored aluminum strand comprises the following steps: step 1, raw material preparation and inspection: selecting a high-carbon steel wire rod, a galvanized steel wire and an aluminum single wire for inspection according to lead use requirements; after the surface of the steel wire rod is treated, the steel wire rod needs to be cold-drawn into the steel wire, and in order to improve the corrosion resistance of the steel wire, the surface of the steel wire is galvanized; according to the production process of the steel-cored aluminum stranded wire, the steel-cored aluminum stranded wire is formed by stranding the high-conductivity aluminum wire stranding layer and the galvanized steel wire, the welding or crimping technology is adopted at the joint of the aluminum wire stranding layer and the steel wire before stranding, and the stranded steel-cored aluminum stranded wire needs to be subjected to heat treatment; the heat treatment can improve the conductivity, strength and hardness of the stranded wire. And a solid insulating layer needs to be extruded outside the stranded wire, so that the functions of improving the insulating property and enhancing the overall strength of the stranded wire are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of cable production, and in particular to a production process of a steel core aluminum stranded wire. Background Art

[0002] Steel-core aluminum stranded wire is a commonly used combined stranded wire, which is made of multiple aluminum single wires and a high-strength steel wire in the center. Steel-core aluminum stranded wire is the main conductor material for high-voltage transmission lines. It has a steel "core" inside and aluminum wires wrapped around the steel core by twisting. The steel core mainly serves to increase strength, and the aluminum stranded wire mainly serves to transmit electrical energy. In daily use or production processes, steel-core aluminum stranded wire is easily affected by external factors.

[0003] The existing technology has the following problems:

[0004] Since the core of the steel core aluminum stranded wire is an aluminum conductor, its surface is easily affected by the environment and oxidized, resulting in increased resistance and local heat release. In the steel core aluminum stranded wire stranding process, the material properties of the steel core aluminum stranded wire will affect the operating temperature of the grease, and the temperature change of the grease can easily cause oil stains on the wire surface. Since the joints of the steel core aluminum stranded wire are difficult to handle, professional personnel are required to operate, and leakage and local discharge are prone to occur at the joints. Summary of the invention

[0005] The present invention provides a production process of a steel core aluminum stranded wire to solve the problems raised in the above background technology.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] A production process for a steel core aluminum stranded wire, the production process for the steel core aluminum stranded wire comprising the following steps:

[0008] Step 1: Raw material preparation and inspection: According to the use requirements of the conductor, select high carbon steel wire rod, galvanized steel wire and aluminum single wire for inspection;

[0009] Step 2: Steel wire pretreatment: After the surface treatment of the steel wire rod, it needs to be cold drawn into steel wire. In order to improve the corrosion resistance of the steel wire, its surface is galvanized;

[0010] Step 3: Let the aluminum wire stand still: Before twisting, the aluminum wire needs to be left standing for a certain period of time (e.g. ≥24h);

[0011] Step 4: Twisting into strands: twisting multiple high-conductivity hard aluminum single wires to form an aluminum wire stranding layer, and twisting multiple aluminum single wires on galvanized steel wires to form the core of the steel-core aluminum stranded wire;

[0012] Step 5: Heat treatment: Heat treatment is performed on the stranded steel core aluminum stranded wire to improve the electrical conductivity, strength and hardness of the stranded wire;

[0013] Step 6: Insulation and filling: Extrude a solid insulation layer on the outside of the high-stranded wire, and control the eccentricity of the insulation layer within a certain range (such as ≤5%), and then fill the outside of the stranded conductor core with insulating material;

[0014] Step 7: Cutting and packaging: The steel core aluminum stranded wire after the above treatment is cut and packaged according to the specified length, and the packaged products need to be inspected.

[0015] Preferably, the raw material inspection in step 1 includes appearance, size, chemical composition analysis and mechanical property testing.

[0016] Preferably, the steel wire rod that has been cold-drawn in step 2 needs to be stored at room temperature for a period of time (such as 15 to 20 days) or subjected to heat-ineffective treatment (such as heating to 100° C. to 200° C. and maintaining it for a certain period of time).

[0017] Preferably, the area where the aluminum wires are placed in step three should be clean, free of dust and corrosive gases, and the aluminum wires should be placed flat and appropriately spaced in a fixed number and order.

[0018] Preferably, in the step 4, an oxygen barrier layer is provided between the multiple aluminum single wires and the steel core for isolation, and the oxygen barrier layer comprises an organic coating, an inorganic coating and a composite coating, the organic coating is composed of polymer materials such as polyolefins and polyesters, and the inorganic coating is composed of materials such as aluminum oxides (such as aluminum oxide) and silicates.

[0019] Preferably, in the step 4, advanced welding or crimping technology is used at the joint before the steel core and the multiple aluminum single wires are twisted together. The crimping technology forms a high-strength mechanical connection by physically connecting the joint to the steel core aluminum stranded wire. The welding technology includes laser welding, arc welding, resistance spot welding and friction welding.

[0020] Preferably, in the steel core aluminum stranded wire stranding process in step 4, a temperature sensor is installed to monitor the temperature of the grease in real time. The grease consists of 50-90% base oil, 1-5% isocyanate, 1-5% fatty amine, 1-6% aromatic amine, 1-6% tackifier, 1-5% rust inhibitor, 0.25-0.8% antioxidant and 0.04-0.08% metal corrosion inhibitor by weight. The optimal operating temperature range of the grease is generally between -40°C and 120°C and is jointly controlled by the heating system, stirring system and temperature control system.

[0021] Preferably, the insulation layer of the steel core aluminum stranded wire in step six uses insulating materials such as cross-linked polyethylene or high-density polyethylene, the average thickness of the insulating material should not be less than the specified value of the subsequent corresponding products, and the minimum thickness of the insulating material should not be less than 90%-0.1mm of the fixed value.

[0022] Due to the adoption of the above technical solution, the present invention has the following technical advances compared with the prior art:

[0023] 1. The present invention provides a production process for steel core aluminum stranded wire, which prevents oxidation of the aluminum wire core by setting an oxygen barrier layer between multiple aluminum single wires and the steel core, and the oxygen barrier layer includes an organic coating, an inorganic coating and a composite coating. The organic coating has good weather resistance and chemical stability, can effectively isolate oxygen and moisture, and prevent oxidation of the aluminum core. The inorganic material of the inorganic coating has high hardness and wear resistance, and can resist erosion from the external environment to a certain extent. The composite coating combines the flexibility of the organic material and the hardness of the inorganic material, and can provide more comprehensive protection for the steel core aluminum stranded wire, and avoid the phenomenon of local heat release of the steel core aluminum stranded wire.

[0024] 2. The present invention provides a production process for steel core aluminum stranded wire. Before applying the grease to the steel wire or aluminum stranded wire, the grease may need to be heated to reduce its viscosity for easy application. The heating temperature can be controlled within the applicable temperature range of the grease by a heating system, a stirring system and a temperature control system to avoid the degradation of the grease performance due to excessively high or low temperature. The temperature sensor is used to detect the grease temperature in real time to avoid the drawing oil adhering to the surface of the aluminum wire when the lubricating oil temperature is too low, thereby improving the production quality of the steel core aluminum stranded wire.

[0025] 3. The present invention provides a production process for steel core aluminum stranded wire, which optimizes the joints of the steel core aluminum stranded wire and adopts more advanced welding or crimping technology to improve the quality of the joints, make the structure of the joint area dense, reduce the residual stress, and improve the safety performance of the production process. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the process flow of the present invention. DETAILED DESCRIPTION

[0027] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0028] like Figure 1 As shown, a production process of a steel core aluminum stranded wire, the production process of the steel core aluminum stranded wire comprises the following steps:

[0029] Step 1: Raw material preparation and inspection: According to the use requirements of the conductor, select high carbon steel wire rod, galvanized steel wire and aluminum single wire for inspection;

[0030] Step 2: Steel wire pretreatment: After the surface treatment of the steel wire rod, it needs to be cold drawn into steel wire. In order to improve the corrosion resistance of the steel wire, its surface is galvanized;

[0031] Step 3: Let the aluminum wire stand still: Before twisting, the aluminum wire needs to be left standing for a certain period of time (e.g. ≥24h);

[0032] Step 4: Twisting into strands: twisting multiple high-conductivity hard aluminum single wires to form an aluminum wire stranding layer, and twisting multiple aluminum single wires on galvanized steel wires to form the core of the steel-core aluminum stranded wire;

[0033] Step 5: Heat treatment: Heat treatment is performed on the stranded steel core aluminum stranded wire to improve the electrical conductivity, strength and hardness of the stranded wire;

[0034] Step 6: Insulation and filling: Extrude a solid insulation layer on the outside of the high-stranded wire, and control the eccentricity of the insulation layer within a certain range (such as ≤5%), and then fill the outside of the stranded conductor core with insulating material;

[0035] Step 7: Cutting and packaging: The steel core aluminum stranded wire after the above treatment is cut and packaged according to the specified length, and the packaged products need to be inspected.

[0036] Reference Figure 1 , steel wire rods and aluminum single wires are inspected separately. After passing the inspection, the steel wire rods are cold-drawn into steel wires, while the aluminum single wires need to be placed for a certain period of time. The steel core aluminum stranded wire is made of high-conductivity aluminum wire stranded layers and galvanized steel wires. Before stranding, welding or crimping technology is used at the joints of the aluminum wire stranded layers and the steel wires. The steel core aluminum stranded wire after stranding needs to be heat treated, which can improve the conductivity, strength and hardness of the stranded wire. The solid insulation layer needs to be extruded on the outside of the stranded wire after stranding to improve the insulation performance and enhance the overall strength of the stranded wire, and the eccentricity of the extruded insulation layer is controlled within a certain range (such as ≤5%).

[0037] Among them, in the raw material inspection, the appearance and size inspection of aluminum single wire and steel wire rod is the basis for ensuring that the two can be twisted together later. At the same time, the chemical composition analysis can test the carbon content in the high-carbon steel wire rod to ensure that it has good hardness and wear resistance. The mechanical property test can ensure that the aluminum single wire and steel wire rod can withstand various stresses during use.

[0038] Among them, after the steel wire rod is cold-drawn, heating or storage at room temperature can release or redistribute the stress inside the steel through the passage of time or the effect of temperature, thereby further improving the yield strength or tensile strength of the steel. Secondly, the steel wire rod needs to be stored at room temperature for a period of time (such as 15 to 20 days) or undergo heat aging treatment (such as heating to 100°C to 200°C and maintaining it for a certain period of time).

[0039] Among them, the area where the aluminum wire is placed should be clean, free of dust and corrosive gas, and the aluminum wire should be placed straight and appropriately spaced in a fixed number and order. The area where the aluminum wire is placed and stored regularly will directly affect the quality of the aluminum wire.

[0040] Among them, the core of the steel core aluminum stranded wire is an aluminum conductor, whose surface is easily oxidized, resulting in increased resistance and local heat release. Setting an oxygen barrier layer between the aluminum core and the steel core can effectively prevent the occurrence of the above situation. The organic coating has good weather resistance and chemical stability, and can effectively isolate oxygen and moisture to prevent oxidation of the aluminum core. The inorganic material of the inorganic coating has high hardness and wear resistance, and can resist the erosion of the external environment to a certain extent. The composite coating combines the flexibility of organic materials and the hardness of inorganic materials, and can provide more comprehensive protection for the steel core aluminum stranded wire.

[0041] Among them, during or after the twisting process, the aluminum stranded wire and the steel wire need to be jointed, which is difficult to handle and is prone to leakage and partial discharge at the joint. Advanced welding or crimping technology can be used at the joints of all steel cores and multiple aluminum single wires during or after twisting. Welding and crimping technology can make the joint area dense, reduce residual stress, and reduce the occurrence of the above phenomena.

[0042] Among them, in order to improve the corrosion resistance of steel core aluminum stranded wire during the stranding process, domestic and foreign manufacturers usually apply anti-corrosion grease made of organic materials between the steel core and the aluminum strand. Among them, the weight proportion of the grease is composed of 50-90% base oil, 1-5% isocyanate, 1-5% fatty amine, 1-6% aromatic amine, 1-6% tackifier, 1-5% rust inhibitor, 0.25-0.8% antioxidant and 0.04-0.08% metal corrosion inhibitor. Since there is a layer of anti-corrosion grease between the steel core and the aluminum stranded wire, the corrosion caused by the potential difference between the two will be significantly weakened. When the lubricating oil temperature is too low, the drawing oil will adhere to the surface of the aluminum wire. Therefore, the temperature sensor can monitor the temperature of the grease in real time, and adjust the temperature of the grease according to the heating system, stirring system and temperature control system required for production.

[0043] Among them, the insulation layer can prevent the copper core from being corroded and increase the service life of the conductor. Cross-linked polyethylene uses chemical or physical cross-linking methods to transform polyethylene molecules from a linear structure to a three-dimensional network structure, thereby improving its heat resistance. This network structure prevents XLPE from decomposing and carbonizing below 300°C, and the long-term working temperature can reach 90°C, and the thermal life can reach 40 years, which is significantly better than ordinary polyethylene materials. High-density polyethylene is insoluble in any organic solvent at room temperature and is resistant to corrosion by acids, alkalis and various salts. This chemical stability allows HDPE insulation materials to maintain stable performance in a variety of chemical environments. It also has good electrical insulation, which makes it an important insulating material in the field of power transmission and distribution. Its high insulation resistance and low dielectric loss tangent help reduce energy loss during power transmission.

[0044] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A production process for steel core aluminum stranded wire, characterized in that: The production process of the steel core aluminum stranded wire comprises the following steps: Step 1: Raw material preparation and inspection: According to the use requirements of the conductor, select high carbon steel wire rod, galvanized steel wire and aluminum single wire for inspection; Step 2: Steel wire pretreatment: After the surface treatment of the steel wire rod, it needs to be cold drawn into steel wire. In order to improve the corrosion resistance of the steel wire, its surface is galvanized; Step 3: Aluminum single wire standing: Before twisting, the aluminum single wire needs to be placed for a certain period of time, and the storage time needs to be ≥ 24h; Step 4: Twisting into strands: twisting multiple high-conductivity hard aluminum single wires to form an aluminum wire stranding layer, and twisting multiple aluminum single wires on galvanized steel wires to form the core of the steel-core aluminum stranded wire; Step 5: Heat treatment: Heat treatment is performed on the stranded steel core aluminum stranded wire to improve the electrical conductivity, strength and hardness of the stranded wire; Step 6: Insulation and filling: Extrude a solid insulation layer on the outside of the high-stranded wire, and control the eccentricity of the insulation layer within a certain range. The eccentricity range should be ≤5%, and then fill the outside of the stranded conductor core with insulating materials; Step 7: Cutting and packaging: The steel core aluminum stranded wire after the above treatment is cut and packaged according to the specified length, and the packaged products need to be inspected.

2. The production process of a steel core aluminum stranded wire according to claim 1, characterized in that: The raw material inspection in step 1 includes appearance, size, chemical composition analysis and mechanical property testing.

3. The production process of a steel core aluminum stranded wire according to claim 1, characterized in that: The steel wire rod that has been cold drawn in step 2 needs to be stored at room temperature for 15 to 20 days or be subjected to a heating aging treatment, and the temperature range during the heating should be controlled between 100° C. and 200° C.

4. The production process of a steel core aluminum stranded wire according to claim 1, characterized in that: In the step 3, the area where the aluminum single wires are placed should be clean, free of dust and corrosive gases, and the aluminum single wires should be placed in a fixed number and order, straight and with appropriate spacing.

5. The production process of a steel core aluminum stranded wire according to claim 1, characterized in that: In the step 4, an oxygen barrier layer is provided between the multiple aluminum single wires and the steel core for isolation, and the oxygen barrier layer includes an organic coating, an inorganic coating and a composite coating. The organic coating is composed of polyolefin and polyester polymer materials, and the inorganic coating is composed of aluminum oxide alumina and silicate materials.

6. The production process of a steel core aluminum stranded wire according to claim 1, characterized in that: In the step 4, advanced welding or crimping technology is used at the joints during or after the steel core and multiple aluminum single wires are twisted. The crimping technology physically connects the joint to the steel core aluminum stranded wire to form a high-strength mechanical connection. The welding technology includes laser welding, arc welding, resistance spot welding and friction welding.

7. The production process of a steel core aluminum stranded wire according to claim 1, characterized in that: In the steel core aluminum stranded wire stranding process in step 4, a temperature sensor is installed to monitor the temperature of the grease in real time. The grease is composed by weight of 50-90% base oil, 1-5% isocyanate, 1-5% fatty amine, 1-6% aromatic amine, 1-6% viscosity enhancer, 1-5% rust inhibitor, 0.25-0.8% antioxidant and 0.04-0.08% metal corrosion inhibitor. The optimal operating temperature range of the grease is generally between -40°C and 120°C and is jointly controlled by a heating system, a stirring system and a temperature control system.

8. The production process of a steel core aluminum stranded wire according to claim 1, characterized in that: In step six, the insulation layer of the steel core aluminum stranded wire uses cross-linked polyethylene and high-density polyethylene insulation materials. The average thickness of the insulation material should not be less than the specified value of the subsequent corresponding products, and the minimum thickness of the insulation material should not be less than 90%-0.1mm of the fixed value.

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