Light submarine cable and cable steel wire armoring preparation process

Abstract

The invention discloses a light submarine cable and a cable steel wire armoring preparation process. The light submarine cable is characterized by comprising a wire, a sheath, a linear armoring and an armoring insulating layer, the product can meet the electrical performance of a submarine power transmission cable, reduces the outer diameter and weight of the cable, enables the laying of submarine cables in near and shallow seas not to depend on a large-scale workboat, is simple in structural design, is provided with structural waterproof and tensile elements, reduces the weight of the cable by about 40% compared with a cable in Shengshi, greatly reduces the construction difficulty, and improves the construction efficiency. The cable has an environment-friendly and seawater-resistant function, can be applied to a flowing offshore environment or a non-flowing beach direct burial environment, and is relatively simple in operation difficulty and low in construction cost.

Description

Technical Field

[0001] The present invention relates to the technical field of transmission cables, and particularly to a lightweight submarine cable and a preparation process for cable steel wire armor. Background Art

[0002] At present, due to the long replacement cycle of general submarine cables, in order to cope with the harsh working environment and external damage caused by complex environments, a double-layer steel wire armor and a double-sheath structure are generally adopted. Therefore, the outer diameter of the cable is large and the weight is heavy. When laying the cable, a large working ship equipped with a large crane is often used, and the operation difficulty is quite high and the construction cost is high.

[0003] With the development of clean energy technology, offshore wind resources have made the construction of offshore wind power stations more and more common. However, the seawater depth in offshore waters is usually less than 8 meters, and large construction ships suitable for deep-sea cabling are prone to stranding. Therefore, the relatively heavy double-layer steel wire armored deep-sea submarine cable is no longer suitable for the laying requirements of nearshore and shallow waters. Therefore, it is necessary to develop a lightweight submarine power transmission cable suitable for the laying conditions of nearshore and shallow waters. Summary of the Invention

[0004] The present invention provides a lightweight submarine cable and a preparation process for cable steel wire armor for the problems mentioned in the background art, which can reduce the outer diameter and weight of the cable while meeting the electrical performance of the submarine power transmission cable, so that the laying of submarine cables in nearshore and shallow waters no longer depends on large construction ships, and the operation difficulty is relatively simple and the construction cost is low.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: An offshore lightweight submarine cable, characterized by comprising a conductor, a sheath, a linear armor, and an armor insulating layer; There are three conductors, and each conductor includes a conductor, an inner shielding layer, an insulating layer, an outer shielding layer, and a copper tape shielding layer. The conductor is a profiled conductor with a compaction coefficient greater than or equal to 0.98. The inner shielding layer is a polymer material extruded on the conductor to uniform the electric field. The insulating layer is a water-tree resistant cross-linked polyethylene material to prevent the cable from being broken down due to the water-tree phenomenon. The outer shielding layer is extruded on the insulating layer to play the same role as the inner shielding layer in uniforming the electric field. The copper tape shielding layer is overlapped and wound around the outer shielding layer with an overlap rate of 15% and a copper tape thickness of 0.1 mm; The three conductors are stranded clockwise into a cable core, and a layer of the sheath is extruded outside the cable core. The sheath is made of PVC material and plays a waterproof role.

[0006] A further solution of the present invention is that the linear armor layer is composed of a number of low-carbon galvanized steel wires stranded and densely arranged on the outer surface of the sheath through a back-twisting and stranding process. The diameter of a single steel wire is selected as 1.6 or 2.0 mm. A layer of steel wire insulation layer is extruded on the outer surface of each steel wire of the linear armor layer. The steel wire insulation layer is HDPE high-density polyethylene. The extruded linear armor layer of HDPE polyethylene material is closely attached to the sheath, which can overcome the "lantern" loosening phenomenon of the linear steel armor.

[0007] The present invention also relates to a preparation process for the steel wire armor of a light submarine cable, which is characterized by including the following process steps: Step 1, pretreatment: Select a number of low-carbon galvanized steel wires with a diameter of 1.6 - 2.0 mm for the armor steel wires. The coiled steel wires are first placed on a conical rotating tray, and then wound around a φ500 take-up reel through an air guide pulley, a protective coil, a positioner, and an "S"-type pretreatment device to eliminate the internal stress of the steel wires. Step 2, extruding the steel wire insulation layer: First, ultrasonically clean and dry the steel wires to eliminate the oil stains and dust on the surface, and then use an SJ-70 extruder to extrude the HDPE insulating material on the surface of each steel wire by non-adjustable offset extrusion. The processing temperatures of each section are 180 - 230 °C to ensure uniform plasticization of the insulating material. Step 3, cooling the steel wire insulation layer: After the steel wires are extruded with the HDPE insulation layer, they are cooled by a segmented water tank. The water temperature of the front section is 85 - 96 °C, and the water temperature of the rear section of the water tank is cold water at room temperature. The production speed is controlled at 30 - 40 meters per minute to eliminate the internal stress of the insulation layer material. Finally, the steel wires with the extruded insulation layer are wound around the corresponding take-up reels for standby. Step 4, cage stranding of the steel wire armor: Load the coiled steel wires with the insulation layer onto the stranding body of a cage strander. Use a magnetic powder tensioner to control the pay-off tension of the cradle to ensure a constant and consistent tension during the production process. The steel wires pass through the threading holes of the cradle and enter the pre-twisting wheels of the front and rear dividing plates. The height of the sudden-twisting wheels of the dividing plates is adjustable, and the distance between the dividing plates is adjustable to ensure that the steel wires enter the collective die, and the wire entry angle is between 72 degrees and 75 degrees. Finally, they enter the sizing die straight. Place the cable core with the inner sheath extruded in the center, apply a hot melt adhesive layer with a thickness of 1 mm - 2 mm on the surface of the inner sheath of the cable core, and then input the stranding pitch on the upper part of the cage strander to start the cage stranding production. Step 5, take-up: The take-up traction uses a tracked traction take-up of 800 kg or 1200 kg. Do not choose a wheeled traction to prevent the generation of excessive extra length when the armor layer bends, causing "lantern". The take-up reel is selected as a full-iron reel or an iron-wood reel with an inner diameter of φ1000 - φ2800 for take-up. The end is tightened with a metal clamp suitable for the cable diameter to prevent the end from loosening.

[0008] A further solution is as follows: in the step of bunch-stranding steel wire armoring, when applying the hot-melt adhesive layer, the application temperature of the hot-melt adhesive is 85°C - 96°C. On the one hand, it ensures that the PVC layer will not melt, and at the same time serves the purpose of bonding the two plastics. On the other hand, after cooling, the hot-melt adhesive has a waterproof effect and increases the roughness of the two surfaces, that is, increases the frictional resistance.

[0009] A further solution is as follows: in the step of bunch-stranding steel wire armoring, in order to obtain a proper bonding effect, the VA content in the EVA resin in the selected hot-melt adhesive is 22% - 38%, and the melt index (MI) is 22 - 600; when the VA content in the EVA resin in the hot-melt adhesive is low, the higher the crystallinity, the greater the hardness. Under the same conditions, when the VA content is large, the crystallinity is low and the elasticity increases. In addition, the smaller the EVA melt index, the poorer the fluidity, the greater the strength, the higher the melting temperature, and the poorer the wetting and permeability to the adherend. On the contrary, when the melt index is too large, the melting temperature of the adhesive is low, the fluidity is better but the bonding strength decreases. The above material indexes are to meet the usage requirements of the cable of the present invention.

[0010] A further solution is as follows: in the step of bunch-stranding steel wire armoring, the calculation method of the number of armoring steel wires is as follows: The number of steel wires n = {π×(outer diameter D of the inner sheath + diameter d of the steel wire)} ÷ diameter d of the steel wire × Sinα, where α is the lay angle, and α is taken as 72° - 75°.

[0011] The beneficial effects of the present invention are as follows: the product can meet the electrical performance of the submarine power transmission cable while reducing the outer diameter and weight of the cable, making the laying of submarine cables in near and shallow seas no longer rely on large construction ships. The cable structure design is simple, with a structural waterproof and tensile element. Compared with deep-sea cables, the unit weight is reduced by about 40%, greatly reducing the construction difficulty. The cable has the functions of environmental protection and seawater resistance, and the application scenarios can be flowing offshore or non-flowing beach direct burial environments, with relatively simple operation difficulty and low construction cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic structural diagram of an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0013] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Embodiment

[0014] As Figure 1 shown, an offshore light submarine cable includes a conductor, a sheath 6, a linear armor 7, and an armor insulation layer 8; There are three wires, each wire including a conductor 1, an inner shielding layer 2, an insulating layer 3, an outer shielding layer 4 and a copper tape shielding layer 5. The conductor 1 is a shaped wire conductor with a compaction coefficient greater than or equal to 0.98. The inner shielding layer 2 is made of a polymer material and is extruded on the conductor 1 to uniform the electric field. The insulating layer 3 is a water-tree resistant cross-linked polyethylene material to prevent the cable from being broken down due to the water-tree phenomenon. The outer shielding layer 4 is extruded on the insulating layer 3 and plays the same role as the inner shielding layer 2 in uniforming the electric field. The copper tape shielding layer 5 is overlapped and wound on the outer shielding layer with an overlap rate of 15% and a copper tape thickness of 0.1 mm; The three wires are stranded clockwise to form the core of the cable, and a sheath 6 is extruded outside the core. The sheath 6 is made of PVC material and plays a waterproof role. Embodiment

[0015] It also relates to a preparation process for the wire armor of a light submarine cable, which includes the following process steps: Pretreatment: Select several low-carbon galvanized steel wires with a diameter of 1.6 - 2.0 mm for the armor steel wires. The coiled steel wires are first placed in a conical rotating tray, and then wound around a φ500 take-up reel through an air guide pulley, a protective coil, a positioner and an "S"-type pretreatment device to eliminate the internal stress of the steel wires; Extruding the steel wire insulating layer: First, ultrasonically clean and dry the steel wires to eliminate the oil stains and dust on the surface, and then use an SJ-70 extruder to extrude the HDPE insulating material on the surface of each steel wire by non-adjusting offset extrusion. The processing temperatures of each section are 180 - 230 °C to ensure uniform plasticization of the insulating material; Cooling the steel wire insulating layer: After the steel wires are extruded with the HDPE insulating layer, they are cooled by a segmented water tank. The water temperature of the front section is 85 °C - 96 °C, and the water temperature of the rear section water tank is cold water at room temperature. The production speed is controlled at 30 - 40 m / min to eliminate the internal stress of the insulating layer material. Finally, the steel wires with the extruded insulating layer are wound around the corresponding take-up reels for standby; Cage-stranding the steel wire armor: Load the coiled steel wires with the insulating layer onto the stranding body of a cage strander. Use a magnetic powder tensioner to control the pay-off tension of the cradle to ensure a constant and consistent tension during the production process. The steel wires enter the pre-twisting wheels of the front and rear dividing plates through the threading holes of the cradle. The height of the sudden-twisting wheels of the dividing plates is adjustable, and the distance between the dividing plates is adjustable to ensure that the steel wires enter the concentrator die with an incoming wire angle between 72 degrees and 75 degrees. Finally, they enter the sizing die straight. Place the core with the extruded inner sheath in the center, apply a hot melt adhesive layer with a thickness of 1 mm - 2 mm on the surface of the inner sheath of the core, and then input the stranding pitch on the upper part of the cage strander to start the cage stranding production; Take-up: For the take-up traction, a crawler-type take-up with a traction force of 800 kg or 1200 kg is used. A wheel-type traction shall not be selected to prevent excessive extra length from being generated when the armor layer bends, which may cause "lantern" phenomenon. For the take-up spool, a full-iron spool or an iron-wood spool with an inner diameter of φ1000 - φ2800 is selected for take-up. The end is tightened with a metal clamp suitable for the cable diameter to prevent the end from loosening.

[0016] In the step of cage-stranding steel wire armor, when applying the hot melt adhesive layer, the application temperature of the hot melt adhesive is 85°C - 96°C. On the one hand, it ensures that the PVC layer will not melt, and at the same time serves the purpose of bonding the two plastics. On the other hand, after cooling, the hot melt adhesive has a waterproof effect and increases the roughness of the two surfaces, that is, it increases the frictional resistance.

[0017] In the step of cage-stranding steel wire armor, in order to obtain a proper bonding effect, the VA content in the EVA resin of the selected hot melt adhesive is 22% - 38%, and the melt index (MI) is 22 - 600; when the VA content in the EVA resin of the hot melt adhesive is low, the higher the crystallinity, the greater the hardness. Under the same conditions, when the VA content is large, the crystallinity is low and the elasticity increases. In addition, the smaller the EVA melt index, the poorer the fluidity, the greater the strength, the higher the melting temperature, and the poorer the wetting and permeability to the adherend. On the contrary, when the melt index is too large, the melting temperature of the adhesive is low, the fluidity is better but the bonding strength is reduced. The above material indexes are to meet the usage requirements of the cable of the present invention.

[0018] In the step of cage-stranding steel wire armor, the calculation method of the number of armor steel wires is as follows: The number of steel wires n = {π×(outer diameter D of the inner sheath + wire diameter d)} ÷ wire diameter d × Sinα, where α is the lay angle, and α is taken as 72 degrees - 75 degrees.

Claims

1. A lightweight submarine cable, characterized in that Includes conductor, sheath, linear armor and armor insulation layer; There are three wires, each of which includes a conductor, an inner shielding layer, an insulating layer, an outer shielding layer and a copper tape shielding layer. The conductor is a profiled wire conductor with a compression coefficient greater than or equal to 0.

98. The inner shielding layer is a polymer material, which is extruded on the conductor for uniform electric field. The insulating layer is a water-tree resistant cross-linked polyethylene material to prevent the cable from being broken down by water tree phenomenon. The outer shielding layer is extruded on the insulating layer and plays the same role of uniform electric field as the inner shielding layer. The copper tape shielding layer is overlapped and wrapped on the outer shielding layer, with an overlap rate of 15%. The thickness of the copper tape is 0.1 mm. The three conductors are twisted clockwise to form a cable core of the cable, and a layer of the sheath is extruded outside the cable core. The sheath is made of PVC material and has a waterproof effect.

2. A lightweight submarine cable as claimed in claim 1, characterized in that The linear armor layer is composed of a plurality of low-carbon galvanized steel wires twisted and densely distributed on the outer surface of the sheath through a back-twisting twisting process. The diameter of a single steel wire is selected to be 1.6 or 2.0 mm. A steel wire insulation layer is extruded on the outer surface of each steel wire of the linear armor layer. The steel wire insulation layer is HDPE high-density polyethylene. The linear armor layer extruded with HDPE polyethylene material is tightly fitted to the sheath.

3. A process for preparing light submarine cable steel wire armor, characterized in that The process includes the following steps: Step (1), pretreatment: select several low-carbon galvanized steel wires with a diameter of 1.6-2.0 mm for the armored steel wires, put the coiled steel wires into a conical rotating tray, and then wind them on a φ500 take-up reel through an aerial guide wheel, a protective coil, a positioner and an "S" type pretreatment device to eliminate the internal stress of the steel wires; Step (2), extruding the steel wire insulation layer: first, ultrasonically clean and dry the steel wire to remove surface oil and dust, and then use an SJ-70 extruder to extrude the HDPE insulation material onto the surface of each steel wire using a non-biased extrusion method. The processing temperature of each section is 180-230°C to ensure uniform plasticization of the insulation material. Step (3), cooling the steel wire insulation layer: after the steel wire is extruded with the HDPE insulation layer, it is cooled in a segmented water tank, the water temperature of the front section is 85-96°C, and the temperature of the rear section water tank is room temperature cold water, and the production speed is controlled at 30-40 m / min to eliminate the internal stress of the insulation layer material, and finally the steel wire with the extruded insulation layer is wound on the corresponding take-up drum for standby; Step (4), cage-stranded steel wire armoring: the steel wire with an insulating layer after being coiled is loaded onto the stranded body of the cage-stranding machine, and the wire-releasing tension of the cradle is controlled by a magnetic powder tensioner to ensure that the tension is constant during the production process. The steel wire passes through the wire threading hole of the cradle and enters the pre-twisting wheels of the front and rear branching plates. The height of the sudden twisting wheels of the branching plates is adjustable, and the distance between the branching plates is adjustable to ensure that the steel wire enters the assembly die with an entry angle of 72 degrees to 75 degrees. Finally, it enters the sizing die straightly, and the cable core with an inner sheath is placed in the center. A layer of hot melt adhesive with a thickness of 1mm to 2mm is coated on the surface of the inner sheath of the cable core. Then, the twisting pitch is input on the upper side of the cage-stranding machine, and the cage-stranding production begins. Step (5), wire reeling: The wire reeling traction adopts 800kg or 1200kg crawler type traction wire reeling, and the wire reeling reeling adopts a full iron reel or iron wood reel with an inner diameter of φ1000-φ2800. The end is tightened with a metal clamp suitable for the cable diameter to prevent the end from loosening.

4. A process for preparing a light submarine cable steel wire armor as claimed in claim 3, characterized in that In the cage stranded steel wire armoring step, the coating temperature of the hot melt adhesive layer is 85°C-96°C.

5. A process for preparing a light submarine cable steel wire armor as claimed in claim 3 or 4, characterized in that In the cage stranded steel wire armoring step, the VA content of the EVA resin in the selected hot melt adhesive is 22%-38%, and the melt index is 22-600.

6. A process for preparing a light submarine cable steel wire armor as claimed in claim 3 or 4, characterized in that In the cage stranded steel wire armoring step, the number of armored steel wires is calculated as follows: The number of steel wires n = {π×(inner sheath outer diameter D+steel wire diameter d)} ÷ steel wire diameter d×Sinα, where α is the twisting angle, and α is 72 degrees-75 degrees.

7. A process for preparing a light submarine cable steel wire armor as claimed in claim 5, characterized in that In the cage stranded steel wire armoring step, the number of armored steel wires is calculated as follows: The number of steel wires n = {π×(inner sheath outer diameter D+steel wire diameter d)} ÷ steel wire diameter d×Sinα, where α is the twisting angle, and α is 72 degrees-75 degrees.

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