Weather and cracking resistant aluminum alloy power cable

Abstract

The application provides a weather-resistant and crack-resistant aluminum alloy power cable, and relates to the technical field of power cables, which comprises an alloy conductor layer, a shielding layer, an insulation layer and a protective layer; the alloy conductor layer comprises an inner conductive core and a plurality of outer conductive cores, the outer conductive cores are spirally wound and attached to the outer wall of the inner conductive core, the shielding layer is arranged outside the outer conductive cores, the hardness of the inner conductive core is lower than that of the outer conductive core, the conductivity of the inner conductive core is higher than that of the outer conductive core, and the outer conductive cores are made of aluminum alloy; the insulation layer comprises an inner insulation layer and an outer insulation layer, an elastic reinforcing layer is arranged between the inner insulation layer and the outer insulation layer, the protective layer is arranged outside the outer insulation layer, and a buffer connecting layer is arranged between the inner insulation layer and the shielding layer. The application has high conductivity, significantly improves the crack resistance and corrosion resistance of the conductor surface, and ensures the connection tightness between the cable structures.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power cable, in particular to a weather-resistant and crack-resistant aluminum alloy power cable. BACKGROUND

[0002] As the core carrier of power transmission, the performance reliability of power cable is directly related to the safe and stable operation of power grid and power supply quality. With the rapid advancement of national power grid construction, especially the transformation of urban power distribution network, the grid connection of new energy power generation (such as photovoltaic and wind power) and the construction of power facilities in harsh environments such as coastal areas, high cold and high humidity, higher requirements are put forward for the environmental adaptability and long-term service life of power cable. Aluminum alloy conductor cable has been widely used in the field of power transmission, especially in low-voltage distribution network, because of its light weight, relatively low cost and convenient installation and laying. It has become an important alternative to traditional copper cable. However, the traditional aluminum alloy cable has the following structural defects: first, the stress concentration problem of homogeneous conductor is serious. When the conventional equal-hardness aluminum alloy stranded conductor is bent and vibrated, the surface stress cannot be effectively dispersed to the inside, which leads to the preferential initiation of fatigue cracks in the conductive core. Under the penetration of salt spray / industrial corrosion medium, intergranular stress corrosion cracking is further induced, causing sudden core fracture accidents. Second, the thermal expansion mismatch is serious. The difference in linear expansion coefficient between the conductor and the insulation layer produces interfacial shear stress under the cycle of day and night temperature difference, which accelerates the peeling of the insulation layer and the conductor. In addition, the existing cable has a single buffer connection structure, which cannot effectively absorb mechanical vibration energy, leading to relative displacement between the shielding layer and the insulation layer, affecting the stability of signal transmission. At the same time, the bending resistance of the insulation layer is insufficient, which is easy to produce micro-cracks under repeated bending conditions, eventually leading to insulation failure. These defects seriously restrict the long-term reliable operation of aluminum alloy cable in complex environments. SUMMARY

[0003] In view of the above deficiencies of the prior art, the purpose of the embodiments of the present application is to provide a weather-resistant and crack-resistant aluminum alloy power cable, which can solve the technical problems of stress concentration and thermal expansion mismatch of the homogeneous conductor of the aluminum alloy power cable in the prior art.

[0004] The present application provides a weather-resistant and crack-resistant aluminum alloy power cable, which comprises an alloy conductor layer, a shielding layer, an insulation layer and a protective layer.

[0005] The alloy conductor layer comprises an inner conductive core and a plurality of outer conductive cores, the outer conductive cores are spirally wound and attached to the outer wall of the inner conductive core, the shielding layer is arranged outside the outer conductive cores, the hardness of the inner conductive core is lower than that of the outer conductive core, and the conductivity of the inner conductive core is higher than that of the outer conductive core, and the outer conductive core is made of aluminum alloy material.

[0006] The insulating layer comprises an inner insulating layer and an outer insulating layer, an elastic reinforcing layer is arranged between the inner insulating layer and the outer insulating layer, the protective layer is arranged outside the outer insulating layer, and a buffer connecting layer is arranged between the inner insulating layer and the shielding layer;

[0007] The buffer connecting layer comprises an outer fastener arranged on the outer surface of the shielding layer and an inner fastener arranged in the inner insulating layer, and the shielding layer and the inner insulating layer are tightly filled with an inner filling layer, and the outer fastener and the inner fastener are jointly embedded in the inner filling layer.

[0008] The technical scheme provided by the embodiment of the present application has at least the following beneficial effects:

[0009] (1) In the embodiment of the present application, the alloy conductor layer is divided into an inner conductive core and a plurality of outer conductive cores, the inner conductive core is a flexible alloy with high energy absorption effect, and the outer conductive core is a high-strength hard core with crack resistance, which not only ensures the conductivity, but also significantly improves the anti-cracking and corrosion resistance of the conductor surface.

[0010] (2) In the embodiment of the present application, the buffer connecting layer designed has the effect of mechanically anchoring and inhibiting interlayer displacement, avoiding the difference in linear expansion coefficient between the conductor and the insulating layer, and the interface shear stress under the diurnal temperature difference cycle, which accelerates the peeling phenomenon of the insulating layer and the conductor. BRIEF DESCRIPTION OF DRAWINGS

[0011] The accompanying drawings are only for the purpose of illustrating specific embodiments and are not considered as limiting the present application, and in the whole drawings, the same reference signs represent the same parts. Obviously, the drawings described below are only some embodiments described in the embodiments of the present application, and other drawings can be obtained according to these drawings without creative labor for those skilled in the art.

[0012] Figure 1 It is a structural schematic diagram of a weather-resistant and crack-resistant aluminum alloy power cable provided by the embodiment of the present application.

[0013] Figure 2 It is a split structure schematic diagram of a fastening sleeve and an outer conductive core in a weather-resistant and crack-resistant aluminum alloy power cable provided by the embodiment of the present application.

[0014] Figure 3 It is a split structure schematic diagram of a buffer connecting layer of a weather-resistant and crack-resistant aluminum alloy power cable provided by the embodiment of the present application.

[0015] Figure 4 It is a sectional view of a buffer connecting layer of a weather-resistant and crack-resistant aluminum alloy power cable provided by the embodiment of the present application.

[0016] Figure 5is a kind of elastic reinforcing layer sectional view of weather-resistant and cracking-resistant aluminum alloy power cable provided by the embodiment of the present application.

[0017] Figure 6 is a kind of elastic node reinforcing piece distribution structure diagram of weather-resistant and cracking-resistant aluminum alloy power cable provided by the embodiment of the present application.

[0018] Figure 7 is a kind of outer filling layer structure schematic diagram of weather-resistant and cracking-resistant aluminum alloy power cable provided by the embodiment of the present application.

[0019] Figure 8 is a kind of elastic node reinforcing piece structure schematic diagram of weather-resistant and cracking-resistant aluminum alloy power cable provided by the embodiment of the present application.

[0020] Figure 9 is a kind of outer fastener and reinforcing rib connecting structure schematic diagram of weather-resistant and cracking-resistant aluminum alloy power cable provided by the embodiment of the present application.

[0021] BRIEF DESCRIPTION OF DRAWINGS 1-inner conductive core; 2-outer conductive core; 3-fastening sleeve; 4-elastic reinforcing piece; 5-outer filling layer; 6-outer insulation layer; 7-reinforcing strip; 8-weather-resistant sheath layer; 9-barrier layer; 10-adhesive layer; 11-inner insulation layer; 12-inner filling layer; 13-shielding layer; 14-outer fastener; 15-outer ring piece; 16-inner fastener; 17-fastening groove; 18-reinforcing rib; 19-elastic connecting column; 20-inner ring piece. DETAILED DESCRIPTION

[0022] In order to make the person skilled in the art better understand the technical solutions in the embodiments of the present application, the technical solutions of the present application will be described clearly and completely in conjunction with the drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. It should be understood that these descriptions are only exemplary and not intended to limit the scope of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor should be within the scope of protection of the present application.

[0023] In addition, in the following description, the description of known structures and technologies is omitted to avoid unnecessary confusion of the concepts disclosed in the present application.

[0024] The exemplary embodiments will be described in detail hereinbelow, with examples shown in the drawings. In the following description, the same numbers in different drawings represent the same or similar elements unless otherwise expressed. The embodiments described in the following exemplary embodiments do not represent all the embodiments consistent with the present application.

[0025] Reference is made to the drawings accompanying Figures 1 to 9The application provides a weather-resistant and crack-resistant aluminum alloy power cable, which comprises an alloy conductor layer, a shielding layer 13, an insulation layer and a protective layer.

[0026] The alloy conductor layer comprises an inner conductive core 1 and a plurality of outer conductive cores 2, the outer conductive cores 2 are spirally wound and attached to the outer wall of the inner conductive core 1, the shielding layer 13 is arranged outside the outer conductive cores 2, the hardness of the inner conductive core 1 is lower than that of the outer conductive core 2, and the conductivity of the inner conductive core 1 is higher than that of the outer conductive core 2, and the outer conductive core 2 is made of an aluminum alloy material.

[0027] The insulation layer comprises an inner insulation layer 11 and an outer insulation layer 6, and an elastic reinforcing layer is arranged between the inner insulation layer 11 and the outer insulation layer 6, and the protective layer is arranged outside the outer insulation layer 6, and a buffer connecting layer is arranged between the inner insulation layer 11 and the shielding layer 13.

[0028] The buffer connecting layer comprises outer buckles 14 uniformly arranged on the outer surface of the shielding layer 13 and inner buckles 16 uniformly arranged in the inner insulation layer 11, the outer buckles 14 and the inner buckles 16 are arranged in a staggered manner, the shielding layer 13 and the inner insulation layer 11 are tightly filled with an inner filling layer 12, the outer buckles 14 and the inner buckles 16 are jointly embedded in the inner filling layer 12, the inner buckles 14 and the inner buckles 16 are both embedded with reinforcing ribs 18, and the reinforcing ribs 18 extend to the adjacent shielding layer 13 or inner insulation layer 11 at both ends, and the reinforcing ribs 18 can increase the connecting strength of the buckles.

[0029] The inner conductive core 1 of the alloy conductor layer refers to a conductive body located at the center of the cable and having low hardness, which can be realized by using pure aluminum or high-purity aluminum alloy material, and the high conductivity can reduce the overall resistance of the cable. The outer conductive core 2 refers to an aluminum alloy wire material spirally wound on the outer periphery of the inner conductive core 1, which can be realized by using an aluminum alloy material added with magnesium and silicon elements, and the high hardness can improve the bending resistance. The shielding layer 13 refers to a conductive layer wrapped outside the outer conductive core 2, which can be formed by winding a copper strip or an aluminum-plastic composite strip, and is used for suppressing electromagnetic interference. The inner insulation layer 11 and the outer insulation layer 6 refer to high polymer material layers wrapped outside the shielding layer 13 and outside the elastic reinforcing layer respectively, which can be realized by using cross-linked polyethylene or silicone rubber material, and provide electrical insulation protection. The elastic reinforcing layer refers to a buffer structure arranged between the inner and outer insulation layers, which is used for absorbing mechanical deformation. The buffer connecting layer adopts the buckling parts of the outer buckles 14 and the inner buckles 16, and the two are mechanically interlocked through the adhesion of the inner filling layer 12.

[0030] Specifically, the inner conductive core 1 serves as the conductive core of the cable, and its high conductivity reduces the power transmission loss. The outer conductive core 2 is tightly wound in a spiral manner on the surface of the inner conductive core to form a mechanical support structure that disperses stress through the geometric characteristics of the spiral winding when the cable is bent. The shielding layer 13 tightly covers the outer conductive core 2 to suppress the surface corona discharge of the conductor and external electromagnetic interference. The elastic reinforcing layer provided between the inner insulation layer 11 and the outer insulation layer 6 absorbs the thermal expansion difference between the inner and outer layers by elastic deformation when the temperature changes, preventing the insulation layer from cracking. In the buffer connecting layer between the shielding layer 13 and the inner insulation layer 11, the outer fastener 14 and the inner fastener 16 form a three-dimensional interlocking structure under the adhesion of the inner filler layer 12, effectively resisting interlayer shear force. The inner filler layer 12 is made of silicone material with an elastic modulus between the shielding layer 13 and the insulation layer, which uniformly transmits stress and compensates for manufacturing tolerances.

[0031] A plurality of outer conductive cores 2 are collectively sleeved with a fastening sleeve 3, and the inner wall of the fastening sleeve 3 is provided with a fastening groove 17 matched with the outer conductive core 2. The fastening sleeve 3 can be made of metal or high polymer material by extrusion molding process, which is used to constrain the radial displacement of the outer conductive core 2 and prevent relative sliding between the conductive cores during bending vibration.

[0032] The fastening groove 17 is a groove structure distributed circumferentially along the inner wall of the fastening sleeve 3, which can be formed by a mold to form a continuous or intermittent groove consistent with the cross-sectional shape of the outer conductive core 2, used to embed the outer conductive core 2 and form a tight contact with its surface, avoiding uneven stress distribution due to the gap between the contact surfaces.

[0033] The fastening sleeve 3 is provided with a groove structure on the outer surface, and the shielding layer 13 is tightly attached to the outer surface of the fastening sleeve 3.

[0034] When the shielding layer 13 is applied to the surface of the fastening sleeve 3 with a groove structure, the concave-convex profile formed by the groove structure forces the shielding material to fill the groove area during the molding process, forming a mechanical engagement. When the cable is subjected to bending or vibration load, the multi-point anchoring effect produced by the groove structure can disperse shear stress and prevent relative sliding between the shielding layer and the conductor layer. In temperature cycling conditions, the additional contact area provided by the groove structure can compensate for the size change caused by the difference in thermal expansion coefficient of the materials, maintaining the stability of the interface bonding.

[0035] The elastic reinforcing layer comprises an outer filling layer 5 filled between the inner insulation layer 11 and the outer insulation layer 6, a plurality of elastic reinforcing members 4 are equidistantly inlaid in the inner filling layer 5, the elastic reinforcing members 4 are sleeved on the outer side of the inner insulation layer 11, a plurality of elastic node reinforcing members are equidistantly arranged between the inner insulation layer 11 and the outer insulation layer 6, the elastic node reinforcing member comprises an outer ring member 15 inlaid in the inner side of the outer insulation layer 6, the inner insulation layer 11 at the corresponding position of the outer ring member 15 is inlaid with an inner ring member 20, a plurality of elastic connecting columns 19 are uniformly connected between the outer ring member 15 and the inner ring member 20, the elastic connecting columns 19 are inlaid in the inner side of the outer filling layer 5, the elastic reinforcing member 4 is arranged between adjacent elastic node reinforcing members, and the elastic reinforcing member 4 is arranged in a spring shape.

[0036] The outer filling layer 5 forms a uniform stress buffer interface by continuously wrapping the inner insulation layer 11, the elastic reinforcing members 4 are inlaid in the inner side of the outer filling layer 5 in an equidistant spacing manner, and a stiffness gradient distributed along the axial direction of the cable is formed. When the cable is subjected to bending or temperature change, the elastic deformation of the outer filling layer 5 can absorb the displacement difference between the conductor and the insulation layer, and the elastic reinforcing member 4 supports the outer filling layer 5 by deforming itself to avoid excessive concentration of local stress. The design that the elastic reinforcing member 4 is sleeved on the outer side of the inner insulation layer 11 can not only constrain the radial expansion of the inner insulation layer 11, but also offset the compression load applied by the outer insulation layer 6 through elastic restoring force, so as to maintain the overall stability of the insulation layer structure.

[0037] The outer ring member 15 is a ring-shaped support structure for mechanical anchoring with the outer insulation layer 6, which can be made of metal or high polymer composite material, and is combined with the outer insulation layer 6 through a pre-embedding forming process, for dispersing the interfacial shear stress. The inner ring member 20 is a ring-shaped structure for embedded connection with the inner insulation layer 11, which can be made of the same or different material as the outer ring member, and is fixed in the inner side of the inner insulation layer 11 through an injection molding or press fitting process, for providing butt support with the elastic connecting column 19. The elastic connecting column 19 is a columnar elastic element for connecting the outer ring member 15 and the inner ring member 20, which can be made of rubber or silicone material, and is integrally formed with the outer ring member 15 and the inner ring member 20 through a mold pressing process, for absorbing the deformation caused by the thermal expansion difference and maintaining the interlayer bonding force.

[0038] Specifically, when the cable is axially expanded or bent due to temperature change, the outer ring member 15 and the inner ring member 20 form a multi-stage buffer node through the stretching or compression of the elastic connecting column 19. The elastic connecting column 19 is uniformly distributed at the interlayer interface, so that the thermal stress can be dispersed and transmitted in the circumferential direction, avoiding local stress concentration leading to insulation layer peeling. The wrapping effect of the outer filling layer 5 on the elastic connecting column 19 further limits its excessive deformation, which can ensure the stability of the interlayer structure under dynamic load.

[0039] The protective layer includes a weather-resistant sheath layer 8, a barrier layer 9, and an adhesive layer 10. The barrier layer 9 is tightly wrapped outside the outer insulation layer 6 through the adhesive layer 10, and the weather-resistant sheath layer 8 is tightly wrapped outside the barrier layer 9.

[0040] The weather-resistant sheath layer 8 is a protective structure wrapped on the outermost layer of the cable to resist ultraviolet rays, temperature changes, and mechanical wear. It can be implemented by using cross-linked polyethylene or polyvinyl chloride composite materials, which have high weather resistance and can slow down material aging caused by long-term exposure to outdoor environments.

[0041] The barrier layer 9 is a permeation-resistant structure, which can be implemented by using aluminum-plastic composite tape or galvanized steel tape laminated materials. Its dense structure can block the penetration of water, salt mist, and chemical corrosion media into the cable.

[0042] The adhesive layer 10 is an intermediate layer used to bond the barrier layer 9 and the outer insulation layer 6. It can be implemented by using ethylene-vinyl acetate copolymer hot melt adhesive or polyurethane adhesive, which has flexible properties that can buffer interlayer stress caused by temperature changes.

[0043] The barrier layer 9 forms a continuous coating with the outer insulation layer 6 through the adhesive layer 10. After curing, the adhesive layer 10 produces uniform interfacial bonding force, allowing the barrier layer 9 to fit tightly with the outer insulation layer 6 without gaps. The weather-resistant sheath layer 8 is formed by extrusion molding on the surface of the barrier layer 9, forming a complete outer protection system. When the cable is eroded by the external environment, the barrier layer 9 can effectively isolate corrosive media, the adhesive layer 10 can absorb shear stress caused by the difference in thermal expansion between the conductor and the insulation layer through elastic deformation, and the weather-resistant sheath layer 8 can maintain the integrity of the outer structure through its anti-ultraviolet and anti-tear properties.

[0044] The weather-resistant sheath layer 8 has a plurality of reinforcing strips 7 integrally formed on its outer surface. The reinforcing strips 7 are arranged in a spiral pattern. The weather-resistant sheath layer is formed with a plurality of spiral reinforcing strips 7 on its outer surface through a mold co-extrusion process. When the cable is subjected to external mechanical load, the spiral reinforcing strips 7 can evenly distribute local stress to the entire weather-resistant sheath layer 8 along the spiral direction, preventing stress concentration from causing cracking of the weather-resistant sheath layer 8. When the cable expands or contracts due to temperature changes, the geometric shape of the spiral reinforcing strips 7 allows the weather-resistant sheath layer 8 to deform coordinately in the axial and radial directions, thereby reducing the risk of interlayer peeling caused by thermal expansion differences. This effectively prevents the weather-resistant sheath layer 8 from cracking due to mechanical stress or thermal stress in harsh environments, enhancing the long-term service reliability of the cable in harsh conditions such as coastal high-salt mist, high-temperature difference cycles, and avoiding the risk of insulation layer corrosion caused by damage to the weather-resistant sheath layer 8.

[0045] The present application encompasses any alternatives, modifications, equivalent methods and solutions made to the spirit and scope of the present application. In order to make the public have a thorough understanding of the present application, specific details are described in the preferred embodiments of the present application, and the present application can be fully understood without the description of these details by those skilled in the art. In addition, in order to avoid unnecessary confusion to the essence of the present application, well-known methods, processes, procedures, elements and circuits are not described in detail.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of the present application, and not to limit them. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can still be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application. Any changes or replacements easily thought of by those skilled in the art within the technical scope disclosed by the present application should be covered within the protection scope of the present application.

Claims

1. A weather-resistant and crack-resistant aluminum alloy power cable, characterized in that, include: Alloy conductor layer, shielding layer (13), insulating layer and protective layer; The alloy conductor layer includes an inner conductive core (1) and multiple outer conductive cores (2). The outer conductive cores (2) are spirally wound and attached to the outer wall of the inner conductive core (1). The shielding layer (13) is disposed on the outside of the outer conductive cores (2). The hardness of the inner conductive core (1) is lower than that of the outer conductive core (2), and the conductivity of the inner conductive core (1) is higher than that of the outer conductive core (2). The outer conductive core (2) is made of aluminum alloy. The insulating layer includes an inner insulating layer (11) and an outer insulating layer (6). An elastic reinforcing layer is provided between the inner insulating layer (11) and the outer insulating layer (6). The protective layer is provided outside the outer insulating layer (6). At the same time, a buffer connection layer is provided between the inner insulating layer (11) and the shielding layer (13). The buffer connection layer includes an outer fastener (14) uniformly disposed on the outer surface of the shielding layer (13) and an inner fastener (16) uniformly disposed inside the inner insulation layer (11). Meanwhile, an inner filling layer (12) is tightly filled between the shielding layer (13) and the inner insulation layer (11). The outer fastener (14) and the inner fastener (16) are embedded together inside the inner filling layer (12).

2. The weather-resistant and crack-resistant aluminum alloy power cable according to claim 1, characterized in that, A fastening sleeve (3) is provided on the outer side of multiple external conductive cores (2), and a fastening groove (17) matching the external conductive core (2) is provided on the inner wall of the fastening sleeve (3).

3. The weather-resistant and crack-resistant aluminum alloy power cable according to claim 2, characterized in that, The outer surface of the fastening sleeve (3) is provided with a groove structure, and the shielding layer (13) is tightly attached to the outer surface of the fastening sleeve (3).

4. The weather-resistant and crack-resistant aluminum alloy power cable according to claim 1, characterized in that, The elastic reinforcing layer includes an outer filling layer (5) filled between the inner insulation layer (11) and the outer insulation layer (6). Multiple elastic reinforcing members (4) are equidistantly embedded inside the outer filling layer (5), and the elastic reinforcing members (4) are sleeved on the outside of the inner insulation layer (11).

5. The weather-resistant and crack-resistant aluminum alloy power cable according to claim 4, characterized in that, A plurality of elastic node reinforcements are provided at equal intervals between the inner insulation layer (11) and the outer insulation layer (6). The elastic node reinforcements include an outer ring (15) embedded in the outer insulation layer (6), and an inner ring (20) is embedded in the inner insulation layer (11) at the corresponding position of the outer ring (15). A plurality of elastic connecting posts (19) are uniformly connected between the outer ring (15) and the inner ring (20), and the elastic connecting posts (19) are embedded in the outer filling layer (5).

6. The weather-resistant and crack-resistant aluminum alloy power cable according to claim 5, characterized in that, The elastic reinforcing member (4) is disposed between adjacent elastic node reinforcing members, and the elastic reinforcing member (4) is arranged in a spring shape.

7. The weather-resistant and crack-resistant aluminum alloy power cable according to claim 1, characterized in that, The protective layer includes a weather-resistant sheath layer (8), a barrier layer (9), and an adhesive layer (10). The barrier layer (9) is tightly fitted to the outside of the outer insulation layer (6) through the adhesive layer (10), while the weather-resistant sheath layer (8) is tightly fitted to the outside of the barrier layer (9).

8. The weather-resistant and crack-resistant aluminum alloy power cable according to claim 1, characterized in that, Both the outer fastener (14) and the inner fastener (16) are fitted with reinforcing ribs (18), and the two ends of the reinforcing ribs (18) extend into the adjacent shielding layer (13) or inner insulation layer (11).

9. The weather-resistant and crack-resistant aluminum alloy power cable according to claim 1, characterized in that, The outer fastener (14) and the inner fastener (16) are staggered.

10. The weather-resistant and crack-resistant aluminum alloy power cable according to claim 7, characterized in that, The outer surface of the weather-resistant sheath layer (8) is integrally formed with multiple reinforcing strips (7), which are arranged in a spiral shape.

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