Cable water-blocking structure, water-blocking cable and preparation method of cable water-blocking structure

Abstract

The invention relates to the field of cable manufacturing, in particular to a cable water-blocking structure, a water-blocking cable and a preparation method of the cable water-blocking structure, the cable water-blocking structure comprises a first water-blocking layer (511), a metal wire layer (512) is wound outside the first water-blocking layer (511), and a second water-blocking layer (513) is wrapped outside the metal wire layer (512); the inner side and the outer side of the metal wire layer (512) are embedded into the first water-blocking layer (511) and the second water-blocking layer (513) respectively, the metal wire layer is embedded into the water-blocking layers through tension adjustment and mold pressing, and the remaining water inlet gap is quickly blocked at the first time when water enters the cable in cooperation with the water absorption quick expansibility of the water-blocking layers, so that the overall longitudinal water-blocking performance of the product can be greatly improved.

Description

Technical Field

[0001] The invention relates to the field of cable manufacturing, and in particular to a cable water-blocking structure, a water-blocking cable and a method for preparing the cable water-blocking structure. Background Art

[0002] The laying environment of power cables is complex and diverse. For laying environments with local water or humidity, water-blocking power cables are required. That is, when the cable sheath is partially damaged and water enters, the cable has the ability to prevent the further spread of water. Water-blocking cables can reduce the replacement length of failures caused by water ingress, reduce the difficulty of repairing power failures, and thus reduce the losses caused by power failures. Domestic water-blocking cables mainly refer to external insulation water-blocking, that is, metal shielding and armored structure water-blocking. National standards such as GB / T 12706 and GB / T 11017 and international standards such as IEC 60502 and IEC 60840 have proposed relevant water permeability test methods, all of which require that a water column pressure of 1m height be applied to the water-blocking cable, and 10 thermal cycles be applied during the test. For a test period of more than 10 days, the sample continues to expand and contract, and no water seepage occurs at both ends of the sample, which means that the water permeability test has been passed.

[0003] Common cable water-blocking structures are mainly achieved by wrapping water-blocking tapes, water-blocking yarns and other materials on the upper and lower layers of the cable metal shielding and armor structure, and by using the water-blocking material's expansion when exposed to water. The cable metal shielding and armor layer are mainly divided into two types: metal tape and metal wire. The diameter of the single wire of the metal wire shielding is relatively small, but the metal wire is a sparse winding structure, and usually the average gap does not exceed 4mm, and the maximum gap does not exceed 8mm; although the metal wire armor is a tightly arranged structure, the single wire diameter is relatively large, and the single wire diameter of the land cable thick steel wire armor structure can reach about 4mm. Therefore, whether it is a metal wire shield or a metal wire armor, there are internal gaps or external uneven structures. In multiple water permeability test verifications, it was found that these gaps and uneven structures can easily become water inlet channels inside the cable. If the product only relies on the water absorption and expansion of the water-blocking tape, the water-blocking performance cannot be guaranteed, which also leads to frequent failures in the water permeability test of water-blocking power cables in third-party random inspections.

[0004] Therefore, those skilled in the art are committed to developing a water-blocking structure and a preparation method thereof that can significantly improve the longitudinal water-blocking ability of the cable. Summary of the invention

[0005] In view of the above-mentioned defects in the prior art, the technical problem to be solved by the present invention is to provide a cable water-blocking structure, a water-blocking cable and a method for preparing the cable water-blocking structure.

[0006] To achieve the above-mentioned purpose, the present invention provides a cable water-blocking structure, including a first water-blocking layer, a metal wire layer wrapped around the first water-blocking layer, and a second water-blocking layer wrapped around the metal wire layer; the first water-blocking layer and the second water-blocking layer are respectively embedded in the inner and outer sides of the metal wire layer, and the first water-blocking layer and the second water-blocking layer play a role in water blocking and protecting the insulated wire core.

[0007] Preferably, the first water-blocking layer and the second water-blocking layer are both formed by wrapping a buffer water-blocking tape with a compressibility of more than 60%. The greater the compression of the water-blocking tape, the deeper the metal wire layer can be embedded, and the better the water-blocking effect.

[0008] Preferably, the total embedding depth of the metal wire layer, the first water-blocking layer and the second water-blocking layer is greater than or equal to 70% of the thickness of the metal wire layer. Experiments have shown that when the embedding amount of the metal wire layer exceeds 70%, the water-blocking effect is significantly improved.

[0009] Preferably, the minimum total compression amount of the first water-blocking layer and the second water-blocking layer is greater than or equal to 70% of the thickness of the metal wire layer, that is:

[0010] n×t×60%≥d×70%

[0011] In the above formula, n represents the total number of wrapped layers of the water-blocking tape in the first water-blocking layer and the second water-blocking layer, t represents the nominal thickness of the water-blocking tape, and d represents the thickness of the metal wire layer.

[0012] Preferably, the metal wire layer is formed by winding copper wire or non-magnetic metal wire.

[0013] The present invention also provides a water-blocking cable, comprising any of the above-mentioned cable water-blocking structures.

[0014] Preferably, it also includes a conductor, which serves to transmit electric energy. A conductor shielding layer is sequentially arranged outside the conductor, and the conductor shielding layer serves to equalize the conductor interface field strength; the insulating layer serves to insulate; the insulating shielding layer serves to equalize the insulating field strength; the first cable water-blocking structure serves to block water and provide metal shielding; the inner sheath layer serves to isolate the metal shielding and armor; the second cable water-blocking structure serves to block water and provide metal armor; and the outer sheath layer serves to provide mechanical protection.

[0015] Preferably, the metal wire layer in the first cable water-blocking structure is formed by winding copper wires, and the sparsely wound copper wires serve as the metal shielding structure of the cable, which can conduct leakage current, fault current, charging current, ensure radial distribution of the electric field, and reduce external electromagnetic interference.

[0016] Preferably, the metal wire layer in the second cable water-blocking structure is formed by winding non-magnetic metal wires, and the non-magnetic metal wires are tightly wound as the armor layer of the cable, which can increase the tensile strength of the cable and mainly play a role in mechanical protection.

[0017] The present invention also provides a method for preparing a cable water blocking structure, comprising the following steps:

[0018] S1. Wrap a first water-blocking layer around the insulating shielding layer;

[0019] S2, preparing a plurality of metal wires, adjusting the tension of each metal wire to be uniform, and wrapping the plurality of metal wires to form a metal wire layer;

[0020] S3, winding the metal wire in step S2 to the outside of the first water-blocking layer;

[0021] S4. Use a pressing die to press the wire core after winding the metal wire, so that the bottom of the metal wire is embedded in the first water-blocking layer as much as possible. The inner diameter of the pressing die is calculated according to the following formula:

[0022] D e =D1+2n1t1×60%+2d

[0023] In the above formula, De is the inner diameter of the pressing die, D1 is the outer diameter of the insulating shielding layer, n1 is the number of water-blocking tape layers wrapped in the first water-blocking layer, t1 is the nominal thickness of the water-blocking tape used in the first water-blocking layer, and d is the diameter of the single metal wire;

[0024] S5. Wrap a second water-blocking layer around the metal wire. Assume that the embedded depth of the metal wire is δ. The embedded depth of the metal wire δ is calculated by the following formula:

[0025] δ=D1+2n1t1+2d+2n2t2-D2

[0026] In the above formula, D2 is the outer diameter after wrapping, n2 is the number of water-blocking tape layers wrapped in the second water-blocking layer, and t2 is the nominal thickness of the water-blocking tape used in the second water-blocking layer.

[0027] The beneficial effects of the present invention are as follows: the present invention embeds the metal wire layer into the water-blocking layer through tension adjustment and mold pressing, and combined with the rapid water absorption and expansion of the water-blocking layer, the remaining water inlet gap is quickly blocked at the first time when water enters the cable, which can greatly improve the overall longitudinal water barrier of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a structural schematic diagram of a specific implementation mode of the present invention.

[0029] Figure 2 yes Figure 1 A schematic diagram of the enlarged structure in the middle.

[0030] Figure 3 It is a schematic diagram of a line splitter used in a specific embodiment of the present invention.

[0031] 1. Conductor; 2. Conductor shielding layer; 3. Insulation layer; 4. Insulation shielding layer; 51. First cable water-blocking structure; 511. First water-blocking layer; 512. Metal wire layer; 513. Second water-blocking layer; 6. Inner sheath layer; 52. Second cable water-blocking structure; 7. Outer sheath layer. DETAILED DESCRIPTION

[0032] The present invention is further described below in conjunction with the accompanying drawings and embodiments. It should be noted that in the description of the present invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific manner, and therefore cannot be understood as limiting the present invention. The terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0033] like Figure 1-2 As shown, a cable water-blocking structure includes a first water-blocking layer 511. In this embodiment, the first water-blocking layer 511 is formed by wrapping a buffer water-blocking tape with a compressibility of more than 60%. Specifically, a semi-conductive buffer water-blocking tape whose "water absorption expansion height" and "water absorption expansion rate" meet the requirements of JB / T 10259-2014 "Cable and Optical Cable Water-blocking Tape" can be used. The tape is mainly composed of outer semi-conductive fluffy cotton and inner polyacrylate (water-blocking powder). The difference from conventional water-blocking tape is that the tape is more fluffy and thicker, but its thickness compression can reach more than 60%. In other embodiments, other similar products with similar performance and compression of more than 60% can also be selected.

[0034] In this embodiment, the metal wire layer 512 is formed by winding copper wire or non-magnetic metal wire. The total embedding depth of the metal wire layer 512, the first water-blocking layer 511 and the second water-blocking layer 513 is greater than or equal to 70% of the thickness of the metal wire layer 512. Experiments have shown that the water-blocking performance of the cable water-blocking structure with an embedding depth exceeding 70% is greatly improved.

[0035] In this embodiment, the second water-blocking layer 513 is also formed by wrapping a buffer water-blocking tape with a compressibility of more than 60%. Specifically, a semi-conductive buffer water-blocking tape whose "water absorption expansion height" and "water absorption expansion rate" meet the requirements of JB / T 10259-2014 "Electrical Cable and Optical Cable Water-blocking Tape" can be used. In other embodiments, other similar products with similar performance and a compression of more than 60% can also be selected.

[0036] The inner and outer sides of the metal wire layer 512 are respectively embedded in the first water-blocking layer 511 and the second water layer, and the embedding depth is greater than or equal to 70% of the thickness of the metal wire layer 512. The minimum total compression of the first water-blocking layer 511 and the second water-blocking layer 513 is greater than or equal to 70% of the thickness of the metal wire layer 512, that is:

[0037] n×t×60%≥d×70%

[0038] In the above formula, n represents the total number of wrapped layers of the water-blocking tape in the first water-blocking layer 511 and the second water-blocking layer 513 , t represents the nominal thickness of the water-blocking tape, and d represents the thickness of the metal wire layer 512 .

[0039] For some products with larger metal wire single wire diameters, the wrapping overlap rate of the first water-blocking layer 511 and the second water-blocking layer 513 can be adjusted to about 50%, thereby increasing the number of wrapping layers of the water-blocking tape and making the embedding amount of the metal wire layer 512 exceed 70% of the thickness of the metal wire layer 512.

[0040] The present invention also provides a water-blocking cable, comprising any of the cable water-blocking structures described above, and also comprising a conductor, and the conductor is provided with a conductor shielding layer 2, an insulating layer 3, an insulating shielding layer 4, a first cable water-blocking structure 51, an inner sheath layer 6, a second cable water-blocking structure 52 and an outer sheath layer 7 in sequence outside the conductor. In this embodiment, the conductor is made of copper, and in other embodiments, it can also be made of aluminum or aluminum alloy. The conductor mainly plays the role of transmitting electric energy. The conductor shielding layer 2 is made of semi-conductive cross-linked polyethylene extruded and has the function of homogenizing the conductor interface field strength. The insulating layer 3 is made of cross-linked polyethylene extruded and has the function of insulation. The insulating shielding layer 4 is made of semi-conductive cross-linked polyethylene extruded and has the function of homogenizing the insulation field strength. The inner sheath layer 6 is made of extruded PVC, PE, polyolefin and other materials, and has the function of isolating the metal shield and armor. The outer sheath is made of extruded PVC, PE, polyolefin and other materials, and has the function of mechanical protection. In this embodiment, the metal wire layer 512 in the first cable water-blocking structure 51 is made of copper wire. The metal wire layer 512 in the second cable water-blocking structure 52 is formed by winding non-magnetic metal wires.

[0041] The present invention also provides a method for preparing a cable water blocking structure, comprising the following steps:

[0042] S1. Wrap the first water-blocking layer 511 around the insulating shielding layer 4.

[0043] S2. Prepare several metal wires and adjust the tension of each metal wire to be uniform. Specifically, use a portable digital display dynamometer to adjust the pay-off tension of each metal wire to make it uniform. Then fix the pay-off end of the metal wire to the tail end of the dynamometer, adjust the tension of the wire pay-off reel until the metal wire can be pulled evenly, record the tension value at this time, repeat the above process, and adjust the pay-off tension of each metal wire according to the recorded tension value. If the metal wire is a thin soft copper wire, it is also necessary to use a screw micrometer to measure the diameter of the metal wire before and after pulling. According to the requirements of GB / T 3953-2024 "Electrical Round Copper Wire", the diameter deviation is within ±1%. On this basis, adjust the tension to avoid thinning or breaking.

[0044] S3, winding the metal wire in step S2 to the outside of the first water-blocking layer 511. Specifically, after the tension adjustment is completed, the metal wire winding process is performed. If there are multiple metal wires arranged at intervals, the metal wires can first pass through the wire splitting die and then be wound on the surface of the wire core. The wire splitting die is as follows: Figure 3 As shown, n is the number of metal wires, d is the diameter of a single metal wire, and R1 is the inner diameter of the wire splitter. In this embodiment, the inner diameter of the wire splitter is about 10 mm larger than the outer diameter of the wire core and is made of brass with a thickness of about 2.5 mm. The inner surface of the hole is smooth and free of burrs. If the metal wires are closely arranged concentric conductors or metal wire armor, there is no need to use a wire splitter. The metal wires can be closely arranged by adjusting the number of metal wires or the pitch.

[0045] S4. Use a pressing mold to press the wire core after winding the metal wire. In this embodiment, the pressing mold is a half mold. The mold is made of bakelite or nylon. The wire inlet end of the mold is properly chamfered. The pressing mold allows the bottom of the metal wire to be embedded in the first water-blocking layer 511 as much as possible. The inner diameter of the pressing mold is calculated according to the following formula:

[0046] D e =D1+2n1t1×60%+2d

[0047] In the above formula, De is the inner diameter of the pressing mold, D1 is the outer diameter of the insulating shielding layer 4, n1 is the number of water-blocking tape layers wrapped in the first water-blocking layer 511, t1 is the nominal thickness of the water-blocking tape used in the first water-blocking layer 511, and d is the diameter of the metal wire.

[0048] S5. Wrap the second water-blocking layer 513 around the metal wire. When wrapping, the wrapping tension can be appropriately increased to embed the outer side of the metal wire into the second water-blocking layer 513 as much as possible. Assuming that the embedding depth of the metal wire is δ, the embedding depth of the metal wire δ is calculated by the following formula:

[0049] δ=D1+2n1t1+2d+2n2t2-D2

[0050] In the above formula, D2 is the outer diameter after wrapping, n2 is the number of water-blocking tape layers wrapped in the second water-blocking layer 513, and t2 is the nominal thickness of the water-blocking tape used in the second water-blocking layer 513. Through continuous adjustment, the metal embedding depth δ is greater than or equal to 70% of the wire diameter.

[0051] In order to verify the technical effect of the present invention, the following embodiments are provided:

[0052] As shown in Table 1, this experiment provides cable samples 1-4 of model YJSY73, where both samples 1 and 2 adopt conventional designs in the art, that is, only 0.3mm and 0.5mm thick water blocking tapes are wrapped around the metal wire layer 512, respectively. Sample 1 shows water seepage within one hour of applying the water column, while sample 2 persists until the subsequent second thermal cycle test and begins to seep water. The experimental results of samples 1 and 2 do not meet the corresponding water blocking standards. Samples 3 and 4 both adopt the cable water blocking structure of the present invention, where the embedding depth δ of sample 3 reaches 70% of the thickness of the metal wire, that is, δ≥2d×70%. A third-party authoritative organization conducts a water permeability test according to the international standard IEC 60840. The sample has no water seepage after 10 thermal cycles. The water ingress distance of sample 1 is about 1.0m, while the standard requires the test sample to be 6m, and the water ingress distance is much smaller than the sample length. The embedding depth δ of sample 4 reaches 90% of the diameter of the single metal wire. A third-party authoritative organization conducts a water permeability test in accordance with the national standard GB / T 11017 with higher requirements. The water ingress distance of the metal shielding structure is tested to be about 0.6m, while the standard requires the test sample to be 3m, so the water-blocking performance margin is relatively large.

[0053] Table 1 Comparison of water permeability test results

[0054]

[0055] It can be seen that the cable water-blocking structure designed by the present invention relies on tension adjustment and mold pressing to make the degree of metal wire embedding into the semi-conductive buffer water-blocking layer reach more than 70%, and combined with the rapid water absorption and expansion of the water-blocking tape, the remaining water inlet gap is quickly blocked at the first time when the cable is flooded, which can greatly improve the overall longitudinal water-blocking property of the product.

[0056] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A cable water blocking structure, characterized in that: It comprises a first water-blocking layer (511), a metal wire layer (512) is wound around the first water-blocking layer (511), and a second water-blocking layer (513) is wrapped around the metal wire layer (512); The first water-blocking layer (511) and the second water-blocking layer (513) are respectively embedded in the inner and outer sides of the metal wire layer (512).

2. The cable water blocking structure according to claim 1, characterized in that: The first water-blocking layer (511) and the second water-blocking layer (513) are both formed by wrapping a buffer water-blocking tape with a compressibility of more than 60%.

3. The cable water blocking structure according to claim 1, characterized in that: The total embedding depth of the metal wire layer (512), the first water-blocking layer (511) and the second water-blocking layer (513) is greater than or equal to 70% of the thickness of the metal wire layer (512).

4. The cable water blocking structure according to claim 2, characterized in that: The minimum total compression amount of the first water-blocking layer (511) and the second water-blocking layer (513) is greater than or equal to 70% of the thickness of the metal wire layer (512), that is: n×t×60%≥d×70% In the above formula, n represents the total number of wrapped layers of the water-blocking tape in the first water-blocking layer (511) and the second water-blocking layer (513), t represents the nominal thickness of the water-blocking tape, and d represents the thickness of the metal wire layer (512).

5. The cable water blocking structure according to claim 1, 2 or 3, characterized in that: The metal wire layer (512) is formed by winding copper wire or non-magnetic metal wire.

6. A water-blocking cable, characterized in that: It comprises the cable water blocking structure as described in any one of claims 1-5.

7. The water-blocking cable according to claim 6, characterized in that: It also comprises a conductor (1), wherein the conductor (1) is provided with a conductor shielding layer (2), an insulating layer (3), an insulating shielding layer (4), a first cable water-blocking structure (51), an inner sheath layer (6), a second cable water-blocking structure (52) and an outer sheath layer (7) in sequence on the outside of the conductor (1).

8. The water-blocking cable according to claim 7, characterized in that: The metal wire layer (512) in the first cable water-blocking structure (51) is formed by winding copper wires.

9. The water-blocking cable according to claim 7, characterized in that: The metal wire layer (512) in the second cable water-blocking structure (52) is formed by winding non-magnetic metal wires.

10. A method for preparing a cable water blocking structure, characterized in that: The following steps are involved: S1, wrapping a first water-blocking layer (511) around the insulating shielding layer (4); S2, preparing a plurality of metal wires, adjusting the tension of each metal wire to be uniform, and wrapping the plurality of metal wires to form a metal wire layer (512); S3, winding the metal wire in step S2 to the outside of the first water-blocking layer (511); S4. Use a pressing die to press the wire core after winding the metal wire, so that the bottom of the metal wire is embedded into the first water-blocking layer (511) as much as possible. The inner diameter of the pressing die is calculated according to the following formula: D e =D1+2n1t1×60%+2d In the above formula, De is the inner diameter of the pressing die, D1 is the outer diameter of the insulating shielding layer (4), n1 is the number of water-blocking tape layers wrapped in the first water-blocking layer (511), t1 is the nominal thickness of the water-blocking tape used in the first water-blocking layer (511), and d is the diameter of the metal wire. S5. Wrap a second water-blocking layer (513) around the metal wire. Assume that the embedding depth of the metal wire is δ. The embedding depth of the metal wire δ is calculated by the following formula: δ=D1+2n1t1+2d+2n2t2-D2 In the above formula, D2 is the outer diameter after wrapping, n2 is the number of water-blocking tape layers wrapped in the second water-blocking layer (513), and t2 is the nominal thickness of the water-blocking tape used in the second water-blocking layer (513).

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