Wind energy torsion-resistant aluminum alloy cable and manufacturing method thereof

Abstract

The invention discloses a wind-energy torsion-resistant aluminum alloy cable and a manufacturing method thereof, and relates to the technical field of cables, the wind-energy torsion-resistant aluminum alloy cable comprises a cable core, a braided shielding layer and a sheath layer which are sequentially arranged from inside to outside, and the braided shielding layer and the sheath layer are arranged outside the cable core; the cable core is formed by twisting a plurality of insulated wire cores; each insulating wire core comprises an insulating layer and a torsion-resistant aluminum alloy conductor wrapped by the insulating layer. The torsion-resistant aluminum alloy conductor is obtained by taking an AA8030 aluminum alloy as a matrix and doping silicon, iron, cadmium, scandium, manganese, a carbon nanotube and a graphene nanosheet. By doping silicon, iron, cadmium, scandium, manganese, the carbon nanotubes and the graphene nanosheets, aluminum alloy component grains are refined, the tensile strength and the elongation at break are improved compared with those of existing aluminum alloy, the alloy forms a nano-micron multi-scale reinforced structure through doping of the carbon nanotubes and the graphene nanosheets, and the tensile strength and the elongation at break are improved. And the strength and toughness of the aluminum alloy are jointly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of cables, and particularly relates to a wind energy resistant torsion aluminum alloy cable and a manufacturing method thereof. Background Art

[0002] Wind energy cables are mainly used in wind turbine nacelles and tower barrels, and are divided into control cables, signal cables, torsion-resistant power cables, etc. With the rapid development of the wind power field, the technology of wind energy cables has become increasingly mature. At present, most wind power torsion-resistant cables use copper conductors. As the price of copper rises day by day, replacing copper with aluminum has become an urgent matter. Since the wind energy torsion-resistant cable not only needs to work at temperatures from -40°C to 90°C, but also needs to have strong torsion resistance, the existing aluminum alloy torsion-resistant cables cannot ensure passing the normal temperature torsion test of 10,000 cycles. Moreover, the existing aluminum alloy conductors have relatively poor fatigue resistance and are easily deformed by external forces, with a very high risk of wire breakage. Therefore, it is very necessary to solve the problem of the current aluminum alloy wind energy cable's torsion resistance test and reduce the procurement cost of wind power cables. Summary of the Invention

[0003] In view of the above deficiencies of the prior art, the present invention provides a wind energy resistant torsion aluminum alloy cable with excellent torsion resistance and a manufacturing method thereof.

[0004] To achieve the above invention purpose, the technical solutions adopted by the present invention are as follows:

[0005] Provide a wind energy resistant torsion aluminum alloy cable, which includes a cable core arranged from inside to outside in sequence, and a braided shielding layer and a sheath layer arranged outside the cable core; the cable core is formed by stranding a plurality of insulated wire cores; the insulated wire core includes an insulating layer and a torsion-resistant aluminum alloy conductor wrapped by the insulating layer; the torsion-resistant aluminum alloy conductor is based on AA8030 aluminum alloy and doped with silicon, iron, cadmium, scandium, manganese, carbon nanotubes and graphene nanosheets.

[0006] Further, the torsion-resistant aluminum alloy conductor includes the following components:

[0007] 0.06% - 0.08% silicon, 0.3% - 0.4% iron, 0.1% - 0.15% cadmium, 0.002% - 0.003% scandium, 0.01% - 0.02% manganese, 0.05% - 0.1% carbon nanotubes and 0.01% - 0.03% graphene nanosheets, and the rest is AA8030 aluminum alloy.

[0008] The present invention also provides a manufacturing method of the above-mentioned torsion-resistant aluminum alloy conductor, and the specific steps are as follows:

[0009] S1: Mix carbon nanotubes and graphene nanosheets and then ball mill them into powder;

[0010] S2: Heat the powder obtained in S1 together with the remaining raw materials to 720 °C, stir evenly; cool to obtain an ingot, and hot-roll the ingot at 450 °C to obtain an alloy rod;

[0011] S3: Age the alloy rod in a pulsed magnetic field;

[0012] S4: Cold-draw the alloy rod after aging treatment to obtain alloy single wires, and bunch several alloy single wires to obtain an aluminum alloy strand core; then twist several aluminum alloy strand cores with several carbon fiber filaments to obtain a twisted bundle;

[0013] S5: Perform laser shock aging treatment on the twisted bundle to obtain a torsion-resistant aluminum alloy conductor.

[0014] Further, in step S2, the uniformly stirred melt is subjected to a rapid cooling process with a cooling rate ≥ 100 °C / s.

[0015] Further, in step S3, the parameters of the pulsed magnetic field are: magnetic field strength 1.5 T, frequency 10 Hz; and the alloy rod is maintained at 400 °C for 1 h in the pulsed magnetic field.

[0016] Further, in step S5, the parameters of the laser shock are: wavelength 1064 nm, energy density 5 J / cm 2 , scanning speed 10 mm / s.

[0017] Further, in step S4, when bunching, the direction of the strand core is to the right, and the bunching pitch diameter ratio is 18 - 22 times.

[0018] Further, when twisting the aluminum alloy strand core and the carbon fiber filaments, the twisting direction is to the right, the twisting pitch diameter ratio of the inner layer is 20 - 25 times, and the outermost layer is 16 - 20 times.

[0019] The beneficial effects of the present invention are as follows:

[0020] By doping silicon, iron, cadmium, scandium, manganese, carbon nanotubes and graphene nanosheets, the present invention refines the crystal grains of the aluminum alloy composition, and has improvements in tensile strength and elongation at break compared with existing aluminum alloys. The doping of carbon nanotubes and graphene nanosheets enables the alloy to form a "nano-micron" multi-scale reinforcement structure, jointly improving the strength and toughness of the aluminum alloy. The torsion-resistant aluminum alloy conductor prepared by the method of the present invention can be twisted 15000 - 16500 times at 720 ° - 2160 ° / min at normal ambient temperature, 4000 - 6000 times at 360 ° - 1080 ° / min at -40 °C low temperature, and 13000 - 15000 times at 360 ° - 1080 ° / min at +60 °C high temperature, far exceeding the standard requirements of 10000 times of normal temperature torsion, 2000 times of low temperature torsion, and 10000 times of high temperature torsion.

[0021] By subjecting the invention to pulsed magnetic field aging treatment and laser shock peening treatment, not only can the process time be significantly shortened, but also the aging treatment effect is better. Through the magnetic field-thermal coupling effect, the dislocation movement and the distribution of precipitation phases are dynamically regulated. By adopting pulsed magnetic field aging treatment, the magnetic field drives the dislocation lines to align along a specific direction, forming uniformly distributed nano-precipitation phases (such as Al3Sc and Al3Zr), breaking through the randomness limitation of traditional static aging. By adopting laser shock peening treatment, the stranded conductor is shock-treated to replace traditional high-temperature aging. The laser shock wave forms a compressive stress layer with a depth ≥ 50 μm on the surface of the conductor, which can inhibit the initiation of fatigue cracks and enhance the fatigue resistance and surface hardness of the conductor. Description of the Drawings

[0022] Figure 1 It is a schematic cross-sectional structure diagram of the wind energy torsion-resistant aluminum alloy cable in Embodiment 1;

[0023] Among them, 1, torsion-resistant aluminum alloy conductor; 2, carbon fiber filaments; 3, insulating layer; 4, filling rope; 5, braided shielding layer; 6, sheath layer. Detailed Embodiments

[0024] The following describes the detailed embodiments of the present invention to facilitate those skilled in the art of the present technology to understand the present invention. However, it should be clear that the present invention is not limited to the scope of the detailed embodiments. For those of ordinary skill in the art of the present technology, as long as various changes are within the spirit and scope of the present invention defined and determined by the appended claims, these changes are obvious, and all inventions made using the concept of the present invention are within the scope of protection.

[0025] In the following embodiments, the materials not specifically described are all conventional commercially available chemically pure materials.

[0026] Embodiment 1

[0027] A wind energy torsion-resistant aluminum alloy cable and its manufacturing method include the following steps:

[0028] S1: Preparation of materials: Prepare materials according to the following elemental composition in mass percentage: silicon 0.06% - 0.08%, iron 0.3% - 0.4%, cadmium 0.1% - 0.15%, scandium 0.002% - 0.003%, manganese 0.01% - 0.02%, and carbon nanotubes 0.05% - 0.1%, graphene nanosheets 0.01% - 0.03%, with the balance being AA8030 aluminum alloy and inevitable impurities;

[0029] S2: Mix the AA8030 aluminum alloy with silicon, iron, cadmium, and scandium;

[0030] S3: Pre-disperse carbon nanotubes and graphene nanosheets in aluminum powder by high-energy ball milling (rotation speed: 3000 rpm, time: 2 h);

[0031] S4: Heat the mixture of S2 and S3 in a vacuum induction furnace to 720 °C, inject it into an electromagnetic stirring device (frequency: 50 Hz, power: 5 kW) after melting, and continuously stir for 20 min to ensure uniform distribution of the nanomaterials;

[0032] S5: Cast the molten aluminum alloy obtained in S4, adopt a rapid cooling process with a cooling rate ≥ 100 °C / s to obtain an ingot with a grain size ≤ 10 μm;

[0033] S6: Perform hot rolling on the ingot obtained in S5 at a temperature of 450 °C to obtain an aluminum alloy rod; then place the aluminum alloy rod in a pulsed magnetic field with a magnetic field strength of 1.5 T and a frequency of 10 Hz for aging treatment at 400 °C for 1 h;

[0034] S7: Cold draw the aluminum alloy rod obtained in S6, and draw it through a drawing die to obtain an aluminum alloy single wire with a specification of Φ0.3 mm - Φ0.6 mm. The specific specification is determined according to the cable cross-section and process requirements;

[0035] S8: Stranding: Obtain an aluminum alloy strand core from the aluminum alloy single wires obtained in S7 through a stranding machine. The number of aluminum alloy single wires is determined according to the cable cross-section and process requirements. The direction of the strand core is to the right, and the stranding pitch diameter ratio is 18 - 22 times;

[0036] S9: Regular stranding: Regularly strand multiple aluminum alloy strand cores obtained in S8 according to the cable cross-section size to obtain a torsion-resistant aluminum alloy conductor 1, and at the same time add carbon fiber filaments 2 to enhance the tensile strength. The stranding direction is to the right, the stranding pitch diameter ratio of the inner layer is 20 - 25 times, and the outermost layer is 16 - 20 times; Specifically, when implemented, the proportion of the carbon fiber filaments 2 is 10% - 15%;

[0037] S10: Perform laser shock peening on the torsion-resistant aluminum alloy conductor 1 after the regular stranding in S9, with a wavelength of 1064 nm and an energy density of 5 J / cm 2 , and a scanning speed of 10 mm / s;

[0038] S11: Extrusion: Extrude an insulating layer 3 outside the torsion-resistant aluminum alloy conductor 1 after aging treatment. The insulating layer 3 is produced by an extruder, and the thickness is determined according to the cable cross-section and process requirements;

[0039] S12: Cabling: If the wind energy resistant torsion aluminum alloy cable is a multi-core cable, the insulated cores obtained in S11 are cabled according to the required number of cores. The cabling pitch is 30 - 35 times. The gap between the insulated cores is filled with a filling cord 4, and then a layer of polyester tape is wrapped around; if the wind energy resistant torsion aluminum alloy cable is a single-core cable, a layer of polyester tape is wrapped around the insulated core.

[0040] S13: Braiding: A layer of soft round copper wire or tinned round copper wire is braided outside the core obtained in S12 to form a braided shielding layer 5. To improve the anti-torsion performance of the cable, carbon fiber filaments 2 with high mechanical strength are added to the braiding layer to improve the tensile performance of the cable.

[0041] S14: Sheathing: A sheathing layer 6 is extruded outside the braiding layer. The sheathing layer 6 is produced by an extruder, and the thickness of the sheathing layer 6 is determined according to the cable cross-section and process requirements.

[0042] The above method is used to obtain Figure 1 the cross-sectional structure schematic diagram of the three-core cabled wind energy resistant torsion aluminum alloy cable as shown.

[0043] The bunching and stranding of the strands of the torsion-resistant aluminum alloy conductor 1 adopt the same-direction stranding technology. Its production process is quite simple and does not require complex equipment or advanced technology. In the structure of the same-direction stranded torsion-resistant aluminum alloy conductor 1, all single wires are arranged in the same direction. This design ensures that the current can flow more evenly through the inner and outer parts of the torsion-resistant aluminum alloy conductor 1, effectively weakening the influence of the skin effect. In addition, this technology can also increase the conductivity of the torsion-resistant aluminum alloy conductor 1 by densely stranding multiple single wires together without increasing the cross-sectional area of the torsion-resistant aluminum alloy conductor 1, only by increasing the number of single wires. This characteristic enables the diameter of the torsion-resistant aluminum alloy conductor 1 to be reduced, making it more suitable for application scenarios with limited space. The same-direction stranding also brings a larger contact area and a tighter stranding structure between single wires, which not only enhances the mechanical strength of the torsion-resistant aluminum alloy conductor 1 but also significantly improves its wear resistance and anti-tensile performance. Due to the tight stranding, the relative position between single wires is more stable, reducing the risk of loosening or deformation, thus ensuring that the torsion-resistant aluminum alloy conductor 1 can maintain the stability of its shape and size in various environments and further improving its reliability.

[0044] The braided shielding layer 5 of the present invention comprises tinned copper wires and high-mechanical-strength carbon fiber filaments 2. The design of combining tinned copper wires with high-mechanical-strength carbon fiber filaments 2 significantly improves the service performance and durability of the cable in various complex environments. The braided layer has good flexibility. During the bending and laying processes of the cable, the braided layer can maintain its integrity and will not crack or break due to bending, thus maintaining a good shielding effect. Meanwhile, through a reasonable braiding density design, effective shielding of electromagnetic waves of different frequencies can be achieved. The braided shielding layer can also provide a uniform shielding effect, avoiding interference caused by uneven shielding of signals inside the cable. Since high-mechanical-strength carbon fiber filaments 2 are added to the braided layer, the overall mechanical properties of the braided layer can be significantly improved. When the cable is subjected to external forces such as torsion or tension, the carbon fiber filaments 2 can effectively disperse and absorb these forces, thereby protecting the braided layer from damage. This not only extends the service life of the cable but also ensures the stability and reliability of the cable under various harsh conditions.

[0045] Example 2

[0046] The following method is used to prepare a torsion-resistant aluminum alloy conductor, which includes the following steps:

[0047] S1: Preparation of materials: Prepare materials according to the following elemental composition by mass percentage: silicon 0.06%, iron 0.3%, cadmium 0.1%, scandium 0.002%, manganese 0.01%, carbon nanotubes 0.05%, graphene nanosheets 0.01%, and the balance is AA8030 aluminum alloy and unavoidable impurities;

[0048] S2: Mix AA8030 aluminum alloy with silicon, iron, cadmium, and scandium;

[0049] S3: Predisperse carbon nanotubes and graphene nanosheets in aluminum powder by high-energy ball milling (rotation speed 3000 rpm, time 2 h);

[0050] S4: Heat the mixture of S2 and S3 in a vacuum induction furnace to 720 °C, inject it into an electromagnetic stirring device (frequency 50 Hz, power 5 kW) after melting, and continuously stir for 20 min to ensure uniform distribution of the nanomaterials;

[0051] S5: Cast the molten aluminum alloy obtained in S4, adopt a rapid cooling process with a cooling rate ≥ 100 °C / s to obtain an ingot with a grain size ≤ 10 μm;

[0052] S6: Hot-roll the ingot obtained in S5 at a temperature of 450 °C to obtain an aluminum alloy rod; then place the aluminum alloy rod in a pulsed magnetic field with a magnetic field strength of 1.5 T and a frequency of 10 Hz for aging treatment at 400 °C for 1 h;

[0053] S7: Cold draw the aluminum alloy rod obtained in S6 to obtain an aluminum alloy single wire with a specification of Φ0.4 mm through a wire drawing die;

[0054] S8: Stranding: The aluminum alloy single wires obtained in S7 are made into an aluminum alloy strand core through a stranding machine. The number of aluminum alloy single wires is 10. The direction of the strand core is to the right, and the stranding pitch diameter ratio is 20 times;

[0055] S9: Composite stranding: The three aluminum alloy strand cores obtained in S8 are positively stranded to obtain a torsion-resistant aluminum alloy conductor. At the same time, carbon fiber filaments are added to enhance the tensile strength. The stranding direction is to the right. The stranding pitch diameter ratio of the inner layer is 22 times, and the outermost layer is 18 times; Specifically, when implemented, the proportion of carbon fiber filaments is 15%;

[0056] S10: Perform laser shock peening on the torsion-resistant aluminum alloy conductor after the composite stranding in S9. The wavelength is 1064 nm, and the energy density is 5 J / cm 2 , and the scanning speed is 10 mm / s;

[0057] Example 3

[0058] The difference between this example and Example 2 is that silicon is 0.07%, iron is 0.35%, cadmium is 0.12%, scandium is 0.025%, manganese is 0.15%, and carbon nanotubes are 0.07%, graphene nanosheets are 0.02%, and the balance is AA8030 aluminum alloy and unavoidable impurities; an aluminum alloy single wire with a specification of Φ0.5 mm is obtained through a wire drawing die.

[0059] Example 4

[0060] The difference between this example and Example 2 is that silicon is 0.08%, iron is 0.4%, cadmium is 0.15%, scandium is 0.003%, manganese is 0.02%, and carbon nanotubes are 0.1%, graphene nanosheets are 0.03%, and the balance is AA8030 aluminum alloy and unavoidable impurities; an aluminum alloy single wire with a specification of Φ0.6 mm is obtained through a wire drawing die.

[0061] Example 5

[0062] The difference between this example and Example 2 is that carbon nanotubes are not added, and the proportion of the remaining dopants remains unchanged. The balance is AA8030 aluminum alloy and unavoidable impurities.

[0063] Example 6

[0064] The difference between this example and Example 2 is that graphene nanosheets are not added, and the proportion of the remaining dopants remains unchanged. The balance is AA8030 aluminum alloy and unavoidable impurities.

[0065] Example 7

[0066] The difference between this embodiment and Embodiment 2 is that in step S5, natural cooling is adopted, and the cooling rate is about 10 °C / s.

[0067] Embodiment 8

[0068] The difference between this embodiment and Embodiment 2 is that the laser shock peening treatment in step S10 is cancelled.

[0069] Embodiment 9

[0070] The difference between this embodiment and Embodiment 2 is that AA8030 aluminum alloy is not doped.

[0071] Embodiment 10

[0072] The aluminum alloy conductor cables and the disassembled aluminum alloy single wires obtained in Embodiments 2 to 9 are subjected to performance tests. The test equipment includes micrometer MDQ-80M, digital display electronic tensile testing machine EK10011, wind energy cable torsion testing machine ZY6237, and DC resistance measuring instrument PC36C. The test standards for diameter, tensile strength, elongation at break, and torsion test can be obtained by the equipment itself. The conductivity is calculated by measuring the resistance, and the formula is: where ρ Cu20 is the resistivity of copper at 20 °C, R 20 is the resistance of the aluminum alloy conductor at 20 °C, L is the length of the aluminum alloy conductor, and S is the cross-sectional area of the aluminum alloy conductor. The test results are shown in Table 1 below.

[0073] Table 1

[0074]

[0075] From the data of Embodiments 2 to 4 in Table 1, it can be seen that the single-wire tensile strength of the aluminum alloy conductor cable prepared by the method provided by the present invention can reach 375 - 395 MPa at room temperature, the elongation at break of the single wire at room temperature is 17 - 20%; the conductivity of the aluminum alloy conductor cable is 62.5 - 63.3% IACS, exceeding 61% IACS specified in the GB / T30552-2014 standard; the number of torsion times at normal temperature (at ambient temperature, 720° - 2160° / min) is 15800 - 16300 times, far exceeding 10000 times specified in the GB / T 29631—2013 standard.

[0076] And by comparing Embodiments 5 and 6 with Embodiment 2, it can be seen that after canceling the doping of carbon nanotubes or graphene nanosheets, the single-wire tensile strength, the elongation at break of the single wire, the number of torsion tests of the cable at normal temperature, and the conductivity of the cable are all significantly reduced.

[0077] As can be seen from the comparison between Example 7 and Example 2, after changing the rapid cooling process to normal temperature cooling, the tensile strength of the single wire, the elongation at break of the single wire, the number of times of the cable normal temperature torsion test, and the conductivity of the cable all decreased significantly.

[0078] As can be seen from the comparison between Example 8 and Example 2, after canceling the laser shock peening treatment, the tensile strength of the single wire, the elongation at break of the single wire, the number of times of the cable normal temperature torsion test, and the conductivity of the cable all decreased significantly.

[0079] As can be seen from the comparison between Example 9 and Example 2, when using conventional aluminum alloy, the tensile strength of the single wire, the elongation at break of the single wire, the number of times of the cable normal temperature torsion test, and the conductivity of the cable all decreased significantly.

[0080] In summary, in the method provided by the present invention, whether changing the doping amount, or changing the cooling process or aging treatment, it is impossible to significantly improve the number of cable torsion times at normal temperature. The setting of the doping amount, rapid cooling, and two aging treatments are all indispensable. When doping, rapid cooling, and two aging treatments are satisfied, aluminum alloy single wires and cables with excellent tensile strength, structural stability, torsion resistance, and acid and alkali corrosion resistance can be prepared. It not only fully complies with the specification standards of wind turbine cables, but also is widely applicable to various application scenarios in the field of wind power generation.

Claims

1. A wind energy resistant torsion aluminum alloy cable, characterized in that, It includes a cable core arranged from the inside out in sequence, a braided shielding layer and a sheath layer arranged outside the cable core; the cable core is formed by stranding a plurality of insulated wire cores; the insulated wire core includes an insulating layer and a torsion-resistant aluminum alloy conductor wrapped by the insulating layer; the torsion-resistant aluminum alloy conductor is based on AA8030 aluminum alloy and doped with silicon, iron, cadmium, scandium, manganese, carbon nanotubes and graphene nanosheets.

2. The wind energy resistant torsion aluminum alloy cable according to claim 1, wherein The torsion-resistant aluminum alloy conductor includes the following components: 0.06% - 0.08% silicon, 0.3% - 0.4% iron, 0.1% - 0.15% cadmium, 0.002% - 0.003% scandium, 0.01% - 0.02% manganese, 0.05% - 0.1% carbon nanotubes and 0.01% - 0.03% graphene nanosheets, and the rest is AA8030 aluminum alloy.

3. A manufacturing method of the torsion-resistant aluminum alloy conductor according to claim 1, characterized in that, The specific steps are as follows: S1: Mix the carbon nanotubes and graphene nanosheets and then ball-mill them into powder. S2: Heat the powder obtained in S1 and the remaining raw materials to 720 °C together, stir evenly; cool to obtain an ingot, and hot-roll the ingot at 450 °C to obtain an alloy rod. S3: Perform aging treatment on the alloy rod in a pulsed magnetic field. S4: Cold-draw the alloy rod after aging treatment to obtain alloy single wires, and bunch a number of alloy single wires to obtain an aluminum alloy stranded wire core; then strand a number of aluminum alloy stranded wire cores and a number of carbon fiber filaments to obtain a stranded bundle. S5: Perform laser shock aging treatment on the stranded bundle to obtain the torsion-resistant aluminum alloy conductor.

4. The manufacturing method according to claim 3, characterized in that, In the step S2, the uniformly stirred melt is subjected to a rapid cooling process with a cooling rate ≥ 100 °C / s.

5. The manufacturing method according to claim 3, characterized in that, In the step S3, the parameters of the pulsed magnetic field are: magnetic field strength 1.5 T, frequency 10 Hz; and the alloy rod is maintained at 400 °C for 1 h in the pulsed magnetic field.

6. The manufacturing method according to claim 3, characterized in that In the step S5, the parameters of the laser shock are: wavelength 1064 nm, energy density 5 J / cm 2 , and scanning speed 10 mm / s.

7. The manufacturing method according to claim 3, characterized in that, In the step S4, when bunching, the direction of the stranded wire core is to the right, and the bunching pitch diameter ratio is 18 - 22 times.

8. The manufacturing method according to claim 4, characterized in that, When stranding the aluminum alloy stranded wire core and the carbon fiber filaments, the stranding direction is to the right, the stranding pitch diameter ratio of the inner layer is 20 - 25 times, and the outermost layer is 16 - 20 times.

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