Lightweight aluminum alloy cable based on wire stranded conductor structure

Abstract

The invention relates to the technical field of aluminum alloy cables, in particular to a lightweight aluminum alloy cable based on a wire stranded conductor structure. The lightweight aluminum alloy cable comprises an aluminum alloy conductor and an insulating layer wrapping the aluminum alloy conductor. The aluminum alloy conductor comprises the following components in percentage by weight: 0.04 to 0.12 percent of Fe, 0.01 to 0.40 percent of Cu, 0.4 to 0.6 percent of Mg, 0.04 to 0.1 percent of La, 0.02 to 0.08 percent of Si and the balance of Al; the insulating layer is made of crosslinked polyethylene. The aluminum alloy conductor has good conductivity, and meanwhile, the internal defects of the aluminum alloy conductor are reduced by adding rare earth elements, so that the aluminum alloy conductor has relatively high strength while being relatively light in weight, and the cable is more convenient to install; and the insulating layer made of crosslinked polyethylene has good flame retardance and can effectively protect the internal aluminum alloy conductor.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloy cables, and particularly to a lightweight aluminum alloy cable based on a stranded conductor structure. Background Art

[0002] With the rapid development of the power industry, the demand for cables has gradually increased. Due to the excellent electrical conductivity of copper, copper is mainly used as the conductor in the wire and cable industry at present. However, due to the soaring price of copper, in order to reduce production costs, a method of using aluminum instead of copper as the cable conductor has emerged.

[0003] The existing aluminum conductor cables have poor strength and are prone to breakdown when subjected to external destructive forces. Moreover, the aluminum conductors are prone to oxidation during use, resulting in a significant increase in the internal resistance after long-term use of the conductors, and a short service life. Therefore, the aluminum conductors cannot operate in harsh environments for a long time, which limits the application range of the aluminum conductor cables. Summary of the Invention

[0004] In order to solve the above problems, the present invention provides a lightweight aluminum alloy cable based on a stranded conductor structure.

[0005] The technical solution of the present invention is: a lightweight aluminum alloy cable based on a stranded conductor structure, the lightweight aluminum alloy cable includes an aluminum alloy conductor and an insulating layer wrapped on the aluminum alloy conductor; the components of the aluminum alloy conductor by weight percentage include: Fe 0.04 - 0.12%, Cu 0.01 - 0.40%, Mg 0.4 - 0.6%, La 0.04 - 0.1%, Si 0.02 - 0.08%, and the balance is Al; the insulating layer is made of cross-linked polyethylene.

[0006] Explanation: The aluminum alloy conductor with the above components has good electrical conductivity. At the same time, by adding rare earth elements, the internal defects of the aluminum alloy conductor are reduced, so that the aluminum alloy conductor is lighter in weight and has higher strength while making the cable easier to install, and the insulating layer made of cross-linked polyethylene has good flame retardancy and can effectively protect the internal aluminum alloy conductor.

[0007] Further, the preparation method of the lightweight aluminum alloy cable includes the following steps:

[0008] S1. Add Al, Fe, Cu, and Mg into a melting furnace according to the above ratio, heat to 700 - 850 °C, then add Si and La into the melting furnace, and then fill nitrogen into the melting furnace and stir for 30 - 40 min to obtain alloy liquid;

[0009] S2. Add the refining agent into the alloy liquid, then stir the alloy liquid for 5 - 10 min, let it stand for 10 - 15 min after stirring is completed, remove the scum on the surface of the alloy liquid to obtain the refined alloy liquid; wherein, the addition amount of the refining agent accounts for 0.2 - 0.3% of the total mass of the alloy liquid.

[0010] S3. Use the continuous casting and rolling process to make the refined alloy liquid into aluminum alloy rods with a diameter of 9 - 12 mm, and then make the aluminum alloy rods into aluminum alloy single wires with a diameter of 0.5 - 3 mm through multi-pass drawing.

[0011] S4. Anneal the aluminum alloy single wires once, then use a stranding machine to strand multiple aluminum alloy single wires to obtain an aluminum alloy conductor, and anneal the aluminum alloy conductor a second time.

[0012] S5. Use an extruder to coat cross-linked polyethylene on the aluminum alloy conductor, and then perform steam cross-linking to obtain a lightweight aluminum alloy cable.

[0013] Note: The above preparation method combines the continuous casting and rolling process with the drawing process to prepare aluminum alloy single wires. Then, through one-time annealing, the internal stress generated during the processing of the aluminum alloy single wires is eliminated, enabling the aluminum alloy single wires to have better plastic deformation ability. Next, multiple aluminum alloy single wires are stranded into an aluminum alloy conductor, and through secondary annealing, the internal stress generated during stranding is reduced, and the gap between the aluminum alloy single wires is minimized, making the aluminum alloy conductor have good electrical conductivity and strength.

[0014] Further, in step S4, the method of the one-time annealing is: keep the aluminum alloy single wires at 300 - 350 °C for 1 - 2 h, and then take them out of the furnace and air-cool.

[0015] Note: Through one-time annealing, the stress generated during drawing can be reduced, the size of the aluminum alloy single wires can be stabilized, and at the same time, the plastic deformation performance of the aluminum alloy single wires can be improved, facilitating subsequent stranding.

[0016] Further, in step S4, the method of the second annealing is: keep the aluminum alloy conductor at 250 - 280 °C for 2 - 3 h, and then make the aluminum alloy conductor pass through a coolant at 50 - 60 °C at a speed of 4 - 8 m / min, while passing a DC electric field into the coolant. The relationship between the voltage U of the DC electric field and the stranding radius R of the aluminum alloy conductor is as follows:

[0017]

[0018] wherein, U is the voltage of the DC electric field, the unit is V, k is a coefficient, and its value is 0.2 - 0.5; I is the current of the DC electric field, and its value is 2 - 4 A; R is the stranding radius of the aluminum alloy conductor, the unit is mm, n is the number of strands of the aluminum alloy single wires during stranding; r is the radius of the aluminum alloy single wire, the unit is mm.

[0019] Note: During the secondary annealing, the aluminum alloy conductor is cooled by coolant to reduce the stress inside the aluminum alloy conductor. The coolant can cooperate with the electric field to form a conductive film on the surface of the aluminum alloy monofilament, so that the aluminum alloy monofilaments have good contact with each other and the internal resistance of the aluminum alloy monofilaments is reduced. The conductive film can prevent oxidation on the surface of the aluminum alloy conductor, avoid surface oxidation of the aluminum alloy conductor due to long-term use, and improve the service life of the lightweight aluminum alloy cable.

[0020] Furthermore, the components of the coolant include, by weight: 16-24 parts of polypyrrole, 12-18 parts of silver nitrate, 5-10 parts of benzotriazole, 10-20 parts of sodium petroleum sulfonate, 4-8 parts of polyoxyethylene stearate, 2-6 parts of trimethyl phosphite and 80-90 parts of deionized water.

[0021] Note: The above coolant can penetrate into the gaps between the aluminum alloy monofilaments under the action of the electric field and form a conductive film on the surface of the aluminum alloy monofilaments, so that the aluminum alloy monofilaments have good contact with each other and reduce the internal resistance of the aluminum alloy monofilaments.

[0022] Furthermore, in step S2, the components of the refining agent include, by weight, 20 to 30 parts of cryolite, 15 to 25 parts of sodium carbonate, 8 to 12 parts of magnesium oxide, and 10 to 20 parts of cerium oxide.

[0023] Note: The above refining agent can remove impurities in the alloy liquid, reduce the gas content in the alloy liquid, and reduce defects such as pores in the aluminum alloy rod.

[0024] Furthermore, in step S3, during the continuous casting and rolling, the cooling water pressure of the casting is 0.08-0.20 MPa, the temperature of the ingot is 500-530°C, the rolling speed during rolling is 7-8 m / s, the final rolling temperature is 250-280°C, and the rolling ratio is 20-30.

[0025] Note: The above continuous casting and rolling parameters can ensure the rapid forming of aluminum alloy rods and reduce the internal defects of aluminum alloy rods.

[0026] Furthermore, in step S3, during the pulling, the pulling speed is 6 to 10 m / s.

[0027] Note: Limiting the drawing speed can ensure production efficiency while avoiding uneven material deformation, which will increase the resistance of the aluminum alloy single wire.

[0028] Furthermore, in step S5, the temperature during steam cross-linking is 180-200° C., the pressure is 0.1-0.2 MPa, and the time is 2-4 hours.

[0029] Note: Steam cross-linking can promote the formation of a three-dimensional network structure of cross-linked polyethylene to ensure the strength of the insulation layer.

[0030] The beneficial effects of the present invention are as follows:

[0031] (1) The aluminum alloy conductor of the present invention has good electrical conductivity. At the same time, by adding rare earth elements, the internal defects of the aluminum alloy conductor are reduced, making the aluminum alloy conductor lighter while having higher strength, making the cable more convenient for installation, and the insulating layer made of cross-linked polyethylene has good flame retardancy and can effectively protect the internal aluminum alloy conductor.

[0032] (2) During the secondary annealing of the present invention, the aluminum alloy conductor is cooled by a coolant to reduce the internal stress of the aluminum alloy conductor. Moreover, the coolant can cooperate with the electric field to form a conductive film on the surface of the aluminum alloy single wire, enabling good contact between the aluminum alloy single wires, reducing the internal resistance of the aluminum alloy single wires, and the conductive film can prevent oxidation on the surface of the aluminum alloy conductor, avoiding surface oxidation of the aluminum alloy conductor due to long-term use, and improving the service life of the lightweight aluminum alloy cable. Specific embodiments

[0033] To further elaborate on the methods and achieved effects of the present invention, the technical solutions of the present invention will be clearly and completely described below in combination with experiments.

[0034] Example 1: A lightweight aluminum alloy cable based on a stranded conductor structure. The lightweight aluminum alloy cable includes an aluminum alloy conductor and an insulating layer wrapped around the aluminum alloy conductor; the components of the aluminum alloy conductor by weight percentage include: Fe 0.08%, Cu 0.2%, Mg 0.5%, La 0.08%, Si 0.06%, and the balance is Al; the insulating layer is made of cross-linked polyethylene;

[0035] The preparation method of the lightweight aluminum alloy cable includes the following steps:

[0036] S1. Add Al, Fe, Cu, and Mg into the melting furnace in proportion, heat to 780 °C, then add Si and La into the melting furnace, and then fill nitrogen into the melting furnace and stir for 35 min to obtain alloy liquid; among them, Fe is added in the form of AlFe20 master alloy, Cu is added in the form of AlCu50 master alloy, Mg is added in the form of AlMg50 master alloy, Si is added in the form of AlSi20 master alloy, and La is added in the form of AlLa25 master alloy;

[0037] S2. Add the refining agent into the alloy liquid, then stir the alloy liquid for 8 min, and after stirring, let it stand for 12 min to remove the scum on the surface of the alloy liquid to obtain the refined alloy liquid; among them, the addition amount of the refining agent accounts for 0.25% of the total mass of the alloy liquid; the components of the refining agent by weight include: 25 parts of cryolite, 20 parts of sodium carbonate, 10 parts of magnesium oxide, and 15 parts of cerium oxide;

[0038] S3. The refined alloy liquid is made into aluminum alloy bars with a diameter of 10 mm by the continuous casting and rolling process, and then the aluminum alloy bars are drawn into aluminum alloy single wires with a diameter of 2 mm through 10 passes of drawing.

[0039] During continuous casting and rolling, the cooling water pressure for casting is 0.1 MPa, the billet temperature is 520 °C, the rolling speed during rolling is 7.5 m / s, the final rolling temperature is 260 °C, and the rolling ratio is 25; during drawing, the drawing speed is 8 m / s.

[0040] S4. The aluminum alloy single wires are annealed once, and then 37 aluminum alloy single wires are concentrically stranded by a stranding machine. The central layer is 1 aluminum alloy single wire, the second layer is 6 aluminum alloy single wires, the third layer is 12 aluminum alloy single wires, and the third layer is 18 aluminum alloy single wires. After stranding, an aluminum alloy conductor is obtained, and the aluminum alloy conductor is annealed twice.

[0041] The stranding diameter D of the aluminum alloy conductor is calculated according to the following formula: D = D0 + 2xd; where D0 is the diameter of the central layer, with a value of 2 mm; x is the number of stranding layers, with a value of 3 layers; d is the diameter of the aluminum alloy single wire, with a value of 2 mm; therefore, the stranding diameter D of the aluminum alloy conductor is 14 mm.

[0042] The method of the first annealing is: keeping the aluminum alloy single wires at 325 °C for 1.5 h, and then taking them out of the furnace and air-cooling.

[0043] The method of the second annealing is: filling the cooling liquid into the cooling tank, keeping the aluminum alloy conductor at 265 °C for 2.5 h, and then passing the aluminum alloy conductor through the cooling liquid at 55 °C at a speed of 6 m / min. At the same time, a DC electric field is introduced into the cooling liquid. The graphite plate is used as the anode of the DC electric field, the stainless steel plate is used as the cathode, an adjustable DC power supply is used to connect the graphite plate and the stainless steel plate, and then the graphite plate and the stainless steel plate are put into the cooling liquid. The following relationship exists between the voltage U of the DC electric field and the stranding radius R of the aluminum alloy conductor:

[0044]

[0045] Among them, U is the voltage of the DC electric field, with the unit of V, k is a coefficient, with a value of 0.4; I is the current of the DC electric field, with a value of 3 A; R is the stranding radius of the aluminum alloy conductor, with a value of 7 mm, n is the number of strands of the aluminum alloy single wires during stranding, with a value of 37 strands; r is the radius of the aluminum alloy single wire, with a value of 1 mm; after calculation, the value of U is 45 V.

[0046] And every 8 minutes during the period when the aluminum alloy conductor passes through the cooling liquid, 25 °C cooling liquid is supplemented into the cooling tank to make the temperature of the cooling liquid in the cooling tank return to 55 °C again.

[0047] The components of the coolant include, by weight: 20 parts of polypyrrole, 16 parts of silver nitrate, 8 parts of benzotriazole, 15 parts of sodium petroleum sulfonate, 6 parts of polyoxyethylene stearate, 4 parts of trimethyl phosphite and 85 parts of deionized water;

[0048] S5. Use an extruder to coat the aluminum alloy conductor with cross-linked polyethylene, the coating thickness of the cross-linked polyethylene on the aluminum alloy conductor is 1.8 mm, and then steam cross-linking is performed to obtain a lightweight aluminum alloy cable; the temperature during steam cross-linking is 190°C, the pressure is 0.15 MPa, and the time is 3 hours.

[0049] Embodiment 2: This embodiment is substantially the same as Embodiment 1, except that the components of the aluminum alloy conductor include, by weight percentage, Fe 0.04%, Cu 0.01%, Mg 0.4%, La 0.04%, Si 0.02%, and the balance is Al.

[0050] Embodiment 3: This embodiment is substantially the same as Embodiment 1, except that the composition of the aluminum alloy conductor includes, by weight percentage, Fe 0.12%, Cu 0.40%, Mg 0.6%, La 0.1%, Si 0.08%, and the balance is Al.

[0051] Example 4: This example is basically the same as Example 1, except that the amount of refining agent added accounts for 0.2% of the total mass of the alloy liquid.

[0052] Example 5: This example is basically the same as Example 1, except that the amount of refining agent added accounts for 0.3% of the total mass of the alloy liquid.

[0053] Example 6: This example is basically the same as Example 1, except that the refining agent comprises, by weight, 20 parts of cryolite, 15 parts of sodium carbonate, 8 parts of magnesium oxide and 10 parts of cerium oxide.

[0054] Example 7: This example is basically the same as Example 1, except that the refining agent comprises, by weight, 30 parts of cryolite, 25 parts of sodium carbonate, 12 parts of magnesium oxide and 20 parts of cerium oxide.

[0055] Example 8: This example is basically the same as Example 1, except that the aluminum alloy single wire is kept at 300°C for 1.5 hours during the primary annealing.

[0056] Example 9: This example is basically the same as Example 1, except that the aluminum alloy single wire is kept at 350°C for 1.5 hours during the primary annealing.

[0057] Example 10: This example is basically the same as Example 1, except that during the first annealing, the aluminum alloy single wire is kept at 325 °C for 1 h.

[0058] Example 11: This example is basically the same as Example 1, except that during the first annealing, the aluminum alloy single wire is kept at 325 °C for 2 h.

[0059] Example 12: This example is basically the same as Example 1, except that the aluminum alloy conductor is kept at 250 °C for 2.5 h.

[0060] Example 13: This example is basically the same as Example 1, except that the aluminum alloy conductor is kept at 280 °C for 2.5 h.

[0061] Example 14: This example is basically the same as Example 1, except that the aluminum alloy conductor is kept at 265 °C for 2 h.

[0062] Example 15: This example is basically the same as Example 1, except that the aluminum alloy conductor is kept at 265 °C for 3 h.

[0063] Example 16: This example is basically the same as Example 1, except that the aluminum alloy conductor passes through the coolant at 55 °C at a speed of 4 m / min.

[0064] Example 17: This example is basically the same as Example 1, except that the aluminum alloy conductor passes through the coolant at 55 °C at a speed of 8 m / min.

[0065] Example 18: This example is basically the same as Example 1, except that the value of k is 0.2.

[0066] Example 19: This example is basically the same as Example 1, except that the value of k is 0.5.

[0067] Example 20: This example is basically the same as Example 1, except that the value of I is 2 A.

[0068] Example 21: This example is basically the same as Example 1, except that the value of I is 4 A.

[0069] Example 22: This example is basically the same as Example 1, except that the components of the coolant include, by weight, 16 parts of polypyrrole, 12 parts of silver nitrate, 5 parts of benzotriazole, 10 parts of sodium petroleum sulfonate, 4 parts of polyoxyethylene stearate, 2 parts of trimethyl phosphite, and 80 parts of deionized water.

[0070] Example 23: This example is basically the same as Example 1, except that the components of the coolant include, by weight, 24 parts of polypyrrole, 18 parts of silver nitrate, 10 parts of benzotriazole, 20 parts of sodium petroleum sulfonate, 8 parts of polyoxyethylene stearate, 6 parts of trimethyl phosphite and 90 parts of deionized water.

[0071] Comparative Example 1: With reference to Example 1, the secondary annealing method is as follows: the aluminum alloy conductor is kept at 265° C. for 2.5 hours and then air-cooled out of the furnace.

[0072] Comparative Example 2: Using Example 1 as a reference, no electric field is introduced into the coolant.

[0073] Comparative Example 3: Taking Example 1 as a reference, deionized water was used to replace trimethyl phosphite in the coolant.

[0074] Experimental Example: In order to explore the influence of the parameters of each embodiment on the performance of the cable, the performance of the lightweight aluminum alloy cables prepared in each embodiment and comparative example was tested, and the specific exploration is as follows:

[0075] Experimental Example 1: Investigating the influence of aluminum alloy conductor composition on cable performance

[0076] Using Examples 1 to 3 as experimental comparison, the cable performances under aluminum alloy conductors with different compositions are shown in Table 1 below:

[0077] Table 1 Cable performance under aluminum alloy conductors with different compositions

[0078] Group Tensile Strength (MPa) Conductivity (IACS) Example 1 352 58.5％ Example 2 318 61.2％ Example 3 384 52.9％

[0079] It can be seen from the data in Table 1 that, compared with Examples 1, 2, and 3, as the amount of alloy elements added in the cable increases, its tensile strength gradually increases and its conductivity gradually decreases. Therefore, the composition of the aluminum alloy conductor can be selected as required.

[0080] Experimental Example 2: Investigating the effect of the amount and composition of refining agent on cable performance

[0081] Using Examples 1, 4 to 7 as experimental comparisons, the cable properties obtained under different addition amounts and compositions of the refining agent are shown in Table 2 below:

[0082] Table 2 Cable performance under different addition amount and composition of refining agent

[0083] Group Tensile Strength (MPa) Conductivity (IACS) Example 1 352 58.5％ Example 4 324 54.2％ Example 5 336 53.7％ Example 6 329 56.2％ Example 7 322 55.1％

[0084] It can be seen from the data in Table 2 that, compared with Examples 1, 4, and 5, the tensile strength and conductivity of the cable in Example 1 are both the highest, indicating that the cable performance of Example 1 is the best. This may be because the defects in the aluminum alloy conductor are the least under the amount of refining agent added in Example 1, so the amount of refining agent added selected in Example 1 is the best;

[0085] Comparing Examples 1, 6, and 7: The tensile strength and conductivity of the cable in Example 1 are the highest, indicating that the cable performance in Example 1 is the best. This may be because the microstructure of the aluminum alloy conductor is the most uniform under the refining agent composition in Example 1. Therefore, the refining agent composition selected in Example 1 is the optimal one.

[0086] Experimental Example 3. Exploring the influence of primary annealing parameters on cable performance

[0087] Taking Examples 1, 8 - 11 as experimental comparisons, the cable performances under different primary annealing parameters are shown in Table 3 below:

[0088] Table 3 Cable performances under different primary annealing parameters

[0089] Group Tensile Strength (MPa) Conductivity (IACS) Example 1 352 58.5％ Example 8 331 53.2％ Example 9 325 52.4％ Example 10 342 55.2％ Example 11 347 54.7％

[0090] From the data in Table 3, comparing Examples 1, 8, 9, 10, and 11: The tensile strength and conductivity of the cable in Example 1 are the highest, indicating that the cable performance in Example 1 is the best. This may be because under the primary annealing parameters in Example 1, the grain size of the aluminum alloy conductor is the most uniform. Therefore, the primary annealing parameters selected in Example 1 are the optimal ones.

[0091] Example 4. Exploring the influence of secondary annealing temperature and holding time on cable performance

[0092] Taking Examples 1, 12 - 15 and Comparative Example 1 as experimental comparisons, the cable performances under different secondary annealing temperatures and holding times are shown in Table 4 below:

[0093] Table 4 Cable performances under different secondary annealing temperatures and holding times

[0094] Group Tensile Strength (MPa) Conductivity (IACS) Example 1 352 58.5％ Example 12 337 54.3％ Example 13 341 54.7％ Example 14 333 53.4％ Example 15 325 52.8％ Comparative Example 1 312 47.6％.

[0095] From the data in Table 4, comparing Examples 1, 12, 13, 14, and 15: The tensile strength and conductivity of the cable in Example 1 are the highest, indicating that the cable performance in Example 1 is the best. This may be because under the secondary annealing temperature and holding time selected in Example 1, the aluminum alloy conductor has the fewest grain boundaries and the fewest tissue defects. Therefore, the secondary annealing temperature and holding time selected in Example 1 are the optimal ones;

[0096] Comparing Example 1 and Comparative Example 1: After the secondary annealing is cooled by air cooling, both the tensile strength and conductivity of the cable have decreased. This may be because the aluminum alloy conductor in Example 1 has fewer grain boundaries inside, and the dislocation density decreases. Therefore, the secondary annealing method selected in Example 1 is the optimal one.

[0097] Example 5. Exploring the influence of the speed of the aluminum alloy conductor passing through the coolant on cable performance

[0098] Taking Examples 1, 16, and 17 as experimental comparisons, the cable performances at different passing speeds of the aluminum alloy conductor are shown in Table 5 below:

[0099] Table 5 Cable Performances at Different Passing Speeds of Aluminum Alloy Conductor

[0100] Group Tensile Strength (MPa) Conductivity (IACS) Example 1 352 58.5％ Example 16 342 56.2％ Example 17 337 55.7％

[0101] From the data in Table 5, it can be seen that when comparing Examples 1, 16, and 17: the cable of Example 1 has the highest tensile strength and conductivity, indicating that the cable performance of Example 1 is the best. This may be because at the passing speed of the aluminum alloy conductor selected in Example 1, the grain size inside the aluminum alloy conductor is the most uniform and the grain boundaries are fewer. Therefore, the passing speed of the aluminum alloy conductor selected in Example 1 is the optimal one.

[0102] Example 6. Exploring the Influence of Electric Field Parameters on Cable Performance

[0103] Taking Example 1, Examples 18 - 21, and Comparative Example 2 as experimental comparisons, the cable performances under different electric field parameters are shown in Table 6 below:

[0104] Table 6 Cable Performances under Different Electric Field Parameters

[0105] Group Tensile Strength (MPa) Conductivity (IACS) Example 1 352 58.5％ Example 18 325 53.4％ Example 19 318 52.1％ Example 20 320 53.1％ Example 21 331 54.6％ Comparative Example 2 316 49.2％

[0106] From the data in Table 6, it can be seen that when comparing Examples 1, 18, 19, 20, and 21: the cable of Example 1 has the highest tensile strength and conductivity, indicating that the cable performance of Example 1 is the best. This may be because under the electric field parameters selected in Example 1, a conductive film can be fully formed on the aluminum alloy conductor, and the cooling speed of the aluminum alloy conductor is appropriate, and the grain size inside the aluminum alloy conductor is uniform. Therefore, the electric field parameters selected in Example 1 are the optimal ones;

[0107] When comparing Example 1 with Comparative Example 2: after not applying an electric field to the coolant, the conductivity of the cable decreases significantly. This may be because without an electric field, a conductive film cannot be formed on the surface of the aluminum alloy conductor. Therefore, the secondary annealing method selected in Example 1 is the optimal one.

[0108] Example 7. Exploring the Influence of Coolant Composition on Cable Performance

[0109] Taking Example 1, Examples 22, 23, and Comparative Example 3 as experimental comparisons, the cable performances under different coolant compositions are shown in Table 7 below:

[0110] Table 7 Cable Performances under Different Coolant Compositions

[0111]

[0112]

[0113] As can be seen from the data in Table 7, comparing Examples 1, 22, and 23: The tensile strength and conductivity of the cable in Example 1 are the highest, indicating that the cable performance in Example 1 is the best. This may be because under the coolant composition selected in Example 1, a conductive film can be fully formed on the aluminum alloy conductor. Therefore, the coolant composition selected in Example 1 is the optimal one;

[0114] Comparing Example 1 with Comparative Example 3: After using deionized water to replace trimethyl phosphate in the coolant, the conductivity of the cable decreases. This shows that trimethyl phosphate in the coolant can effectively improve the performance of the coolant. Therefore, the coolant composition selected in Example 1 is the optimal one.

Claims

1. A lightweight aluminum alloy cable based on a stranded conductor structure, characterized in that, The lightweight aluminum alloy cable comprises an aluminum alloy conductor and an insulating layer wrapped on the aluminum alloy conductor; the components of the aluminum alloy conductor include, by weight percentage: Fe 0.04-0.12%, Cu 0.01-0.40%, Mg 0.4-0.6%, La 0.04-0.1%, Si 0.02-0.08%, and the balance is Al; the insulating layer is made of cross-linked polyethylene.

2. The lightweight aluminum alloy cable based on the stranded conductor structure according to claim 1, wherein The method for preparing the lightweight aluminum alloy cable comprises the following steps: S1. Add Al, Fe, Cu and Mg into a smelting furnace according to the ratio, heat to 700-850° C., add Si and La into the smelting furnace, then fill nitrogen into the smelting furnace and stir for 30-40 minutes to obtain alloy liquid; S2, adding a refining agent into the alloy liquid, stirring the alloy liquid for 5 to 10 minutes, standing the alloy liquid for 10 to 15 minutes after stirring, removing the scum on the surface of the alloy liquid, and obtaining a refined alloy liquid; wherein the amount of the refining agent added accounts for 0.2 to 0.3% of the total mass of the alloy liquid; S3, using continuous casting and rolling process to make the refined alloy liquid into an aluminum alloy rod with a diameter of 9 to 12 mm, and then making the aluminum alloy rod into an aluminum alloy monofilament with a diameter of 0.5 to 3 mm through multiple drawing; S4, performing a primary annealing on the aluminum alloy single wire, and then using a stranding machine to twist multiple strands of the aluminum alloy single wire to obtain an aluminum alloy conductor, and performing a secondary annealing on the aluminum alloy conductor; S5. Use an extruder to coat the aluminum alloy conductor with cross-linked polyethylene, and then steam cross-link it to obtain a lightweight aluminum alloy cable.

3. The lightweight aluminum alloy cable based on a stranded conductor structure according to claim 2, wherein, In step S4, the primary annealing method is: keeping the aluminum alloy single wire at 300-350° C. for 1-2 hours, and then taking it out of the furnace and air cooling it.

4. The lightweight aluminum alloy cable based on a stranded conductor structure according to claim 2, wherein In step S4, the secondary annealing method is: the aluminum alloy conductor is kept at 250-280° C. for 2-3 hours, and then the aluminum alloy conductor is passed through a coolant at 50-60° C. at a speed of 4-8 m / min, and a DC electric field is introduced into the coolant at the same time, and the voltage U of the DC electric field and the twist radius R of the aluminum alloy conductor meet the following relationship: Among them, U is the voltage of the DC electric field, the unit is V, k is the coefficient, the value is 0.2~0.5; I is the current of the DC electric field, its value is 2~4A; R is the twisting radius of the aluminum alloy conductor, the unit is mm, n is the number of strands of the aluminum alloy monofilament when twisted; r is the radius of the aluminum alloy monofilament, the unit is mm.

5. The lightweight aluminum alloy cable based on a stranded conductor structure according to claim 4, wherein The components of the coolant include, by weight: 16-24 parts of polypyrrole, 12-18 parts of silver nitrate, 5-10 parts of benzotriazole, 10-20 parts of sodium petroleum sulfonate, 4-8 parts of polyoxyethylene stearate, 2-6 parts of trimethyl phosphite and 80-90 parts of deionized water.

6. The lightweight aluminum alloy cable based on a stranded conductor structure according to claim 2, wherein, In step S2, the components of the refining agent include, by weight, 20 to 30 parts of cryolite, 15 to 25 parts of sodium carbonate, 8 to 12 parts of magnesium oxide, and 10 to 20 parts of cerium oxide.

7. The lightweight aluminum alloy cable based on a stranded conductor structure according to claim 1, wherein In step S3, during continuous casting and rolling, the cooling water pressure for casting is 0.08 - 0.20 MPa, the billet temperature is 500 - 530 °C, the rolling speed during rolling is 7 - 8 m / s, the final rolling temperature is 250 - 280 °C, and the rolling ratio is 20 - 30.

8. The lightweight aluminum alloy cable based on a stranded conductor structure according to claim 1, characterized in that, In step S3, during drawing, the drawing speed is 6 - 10 m / s.

9. The lightweight aluminum alloy cable based on a stranded conductor structure according to claim 1, characterized in that, In step S5, during steam crosslinking, the temperature is 180 - 200 °C, the pressure is 0.1 - 0.2 MPa, and the time is 2 - 4 h.

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