A safe return-to-port cable for a ship and a method of manufacturing the same

Abstract

The application relates to a marine safety return port cable, which comprises, from inside to outside, a conductor, a fireproof layer, an insulation layer, a heat insulation layer, a shielding layer and a sheath layer; the fireproof layer is formed by winding mica tape and glass fiber tape on the surface of the conductor, the fireproof layer is three layers, and the winding directions of the adjacent two layers are different; the fireproof layer is attached to the surface of the conductor through an adhesive, and the adhesive is composed of, in mass percentage, 48-52% of silicone resin, 28-32% of ceramicized zinc borate, 14-16% of nano silicon dioxide and 4-6% of platinum catalyst. The cable designed in the application can maintain the line integrity for more than 180 min under the composite conditions of 830 DEG C flame, vibration and spraying, and is suitable for key loops such as power propulsion systems, emergency lighting and fire fighting facilities of cruise ships.

Description

Technical Field

[0001] This application relates to the field of cables for equipment, and in particular to a marine safety return cable and its manufacturing method. Background Technology

[0002] In the maritime transportation sector, large cruise ships, compared to ordinary vessels, are significantly larger, have more complex internal layouts, and possess a greater number of equipment, making their operational safety, especially in emergency scenarios, subject to more stringent requirements. According to international shipping safety standards, large cruise ships must be capable of safely returning to port in the event of a fire that does not exceed the accident threshold. The electric propulsion system, as the core guarantee for achieving this capability, directly determines whether the cruise ship can provide the power support for the crew and passengers to return safely. Among these systems, the cables of the electric propulsion system, as the key carriers of electrical energy transmission, are crucial to the integrity of their wiring under fire conditions. This not only relates to the continuous power supply of the electrical system but also directly affects the life and property safety of the ship, crew, and passengers. Therefore, the design and evaluation of safe return-to-port for these cables has become a core component of the safety technology system for large cruise ships.

[0003] To ensure the safety of emergency power supply on ships, the International Maritime Organization (IMO) has clearly required that critical power lines on ships must maintain a stable power supply for at least 180 minutes after an accident. However, existing conventional marine cables fail to meet these stringent requirements and exhibit numerous technical deficiencies under complex fire conditions (high temperature + vibration + spraying), primarily in three aspects: First, the mica tape used in conventional cables is too rigid. When the cable is laid or bent due to vibration during a fire, the overlap gaps between the mica tapes increase significantly, making it easy for moisture during spraying to penetrate the conductor, causing short circuits and disrupting power supply continuity. Second, the conventional silicone adhesive used in the mica tape has insufficient temperature resistance. In high-temperature fire environments above 800℃, it carbonizes rapidly, loses its adhesive strength, and causes the mica layer to detach and fail, thus losing its fire-resistant protection. Third, the fire resistance standards for existing cables are relatively simplistic, mostly based on the 750℃ / 90min test conditions in the IEC 60331 standard. This standard cannot cover the complex conditions of "continuous high temperature + ship vibration + spraying cooling" that may occur in large cruise ship fires, making it difficult to guarantee the integrity of the line for a long time (180min) and unable to provide reliable power support for the safe return of cruise ships to port.

[0004] Therefore, existing marine cables have significant shortcomings in material formulation and structural design, and technological breakthroughs are urgently needed to meet the safe return-to-port requirements of large cruise ships. Summary of the Invention

[0005] The purpose of this application is to address the shortcomings of the existing technology and propose a marine cable with good fire resistance and flame retardancy, vibration and shock resistance, spray resistance, and high safety.

[0006] In the first aspect, this application provides a marine safety return cable, which, from the inside out, includes a conductor, a fire-resistant layer, an insulation layer, a heat insulation layer, a shielding layer, and a sheath layer. The refractory layer is formed by wrapping mica tape and fiberglass tape around the surface of the conductor. The refractory layer consists of three layers, with adjacent layers wrapped in different directions. The refractory layer is bonded to the surface of the conductor by an adhesive, which is composed of 48%~52% organosilicon resin, 28%~32% ceramicized zinc borate, 14%~16% nano-silica, and 4%~6% platinum catalyst by mass percentage.

[0007] More specifically, the mica tape has an overlap rate of not less than 50%, and the mica tape has a unit area weight of 35~45g / m². 2 The mica tape used in this application has a light unit area weight, while the unit area weight of mica tape in traditional cable materials is ≥55g / m². Excessive mica content (>50g / m²) can easily lead to excessive bending modulus of the tape (>3.5GPa), and the risk of cracking of mica lap joints under spray vibration during combustion increases by 40%.

[0008] More specifically, the diameter of the mica tape sheet is less than or equal to 50 μm. The mica tape sheet used in this application has a small diameter, resulting in fine scales on the surface of the fire-resistant layer formed by wrapping, good cable flexibility, and a minimum bending radius of ≤6D, while the minimum bending radius of the cable in traditional processes is ≥8D.

[0009] More specifically, the fiberglass tape content in the refractory layer is ≤45%, and the twist coefficient is ≥1200. In this application, the fiberglass tape content in the refractory wrapping layer is relatively low, which avoids the problems of high fiberglass content (>50%) leading to high tape hardness (>85HA) and decreased wrapping adhesion in traditional processes.

[0010] More specifically, the heat insulation layer is composed of ceramicized silicone rubber.

[0011] More specifically, the insulation layer is composed of cross-linked polyethylene (XLPE), which has high electrical insulation properties and can greatly improve the moisture resistance of the insulation layer.

[0012] More specifically, the shielding layer is woven from nickel-plated carbon fiber monofilaments, the outer diameter of which is not less than 0.11 mm. The nickel-plated carbon fiber used in this application has comparable metallic strength to conventional tin-plated copper wire, but under the same shielding resistance, the weight of nickel-plated carbon fiber is only 60% of that of copper wire shielding. Using nickel-plated carbon fiber to form the shielding layer can significantly reduce its weight by more than 40%, facilitating the addition of digital components to ships and improving equipment intelligence.

[0013] More specifically, the gap between the nickel-plated carbon fiber monofilaments is no greater than the outer diameter of the nickel-plated carbon fiber monofilaments.

[0014] More specifically, the sheath layer is composed of polyolefin material with an oxygen index ≥35%.

[0015] Secondly, this application provides a method for preparing the above-mentioned marine safety return-to-port cable, comprising the following steps: S1. The wire material is sequentially drawn, annealed, and bundled to obtain a single wire filament.

[0016] Wire drawing: The wire material is passed through a wire drawing die with a gradually changing aperture inside the wire drawing machine. The corresponding wire drawing die is selected according to the preset aperture. The minimum diameter of the single wire can be produced as small as Ф0.1mm.

[0017] Annealing: After the monofilament is subjected to a high temperature of 580℃~600℃ in an annealing furnace, the crystal lattice within the monofilament, which was broken due to the drawing process, is reassembled and rearranged. Further, the annealed monofilament undergoes tin plating. The annealed monofilament is passed online through a tin furnace at 380℃~400℃, and after being sized by a die at the end of the tin furnace, the molten tin layer is uniformly coated onto the conductor surface. Tin plating improves the conductor's corrosion resistance, solderability, and electrical stability. After annealing and tin plating, the conductor monofilament exhibits an elongation at break of not less than 30%.

[0018] S2. Twist the single wires of the conductor into a conductor, and at the same time wrap the outer surface of the conductor with a fire-resistant layer.

[0019] Monofilaments with a diameter of 0.18mm to 0.5mm and a breaking elongation of not less than 30% are twisted together in a multi-strand (1+6+12+18) pattern to a length of 50mm. 2 ~400mm 2 Conductor.

[0020] In the conductor stranding process, refractory mica fiberglass tape is simultaneously overlapped and wrapped, breaking through the traditional step-by-step processing mode. Stranding and wrapping are performed concurrently to reduce interlayer stress, improve structural density, and achieve a wrapping overlap rate of ≥50%. A three-layer orthogonal wrapping structure (left → right → left, or right → left → right) achieves seamless coverage. During the refractory layer wrapping, the tension is controlled at 0.5-1.0 N / mm² to prevent wrinkles or breakage of the mica fiberglass tape.

[0021] S3. Perform the first extrusion process using a high-speed extruder with a screw diameter of φ80mm-φ90mm and a length-to-diameter ratio of 25:1 to form an insulating layer on the outer surface of the refractory layer.

[0022] S4. Perform the second extrusion process using a high-speed extruder with a screw diameter of φ100mm and a length-to-diameter ratio of 25:1 to extrude a heat insulation layer on the outer surface of the insulation layer.

[0023] S5. A loose winding process is performed, using nickel-plated carbon fiber material wound unidirectionally at a fixed angle on the outer surface of the insulation layer using a cage winding machine to form a shielding layer. Compared to two-way mesh braided shielding, the nickel-plated carbon fiber uses a unidirectional, flexible, loose winding method. Even after bending and twisting during cable routing in small gaps, there are no stress concentration points on the inner surface of the sheath, resulting in higher safety over long-term use.

[0024] S6. A third extrusion process is performed using a high-speed extruder with a screw diameter of φ100mm and a length-to-diameter ratio of 25:1. A sheath layer is formed on the outer surface of the shielding layer by extrusion. The sheath layer is made of PO material with an oxygen index requirement of ≥35% and a temperature resistance rating of -40℃ to 125℃. This yields a marine safety return-to-port cable, and the finished cable meets the IEC 60332-1-2 single-strand vertical burning test.

[0025] The beneficial effects of this application are: This application designs a marine cable that uses a mica tape wrapped around the conductor to form a fire-resistant layer. By quantifying the optimal mica tape content (35-45%), mica sheet diameter (≤50μm), glass fiber content (≤45%), and glass fiber twist coefficient (≥1200), the optimal balance between flexibility and fire resistance is achieved. A novel high-temperature resistant adhesive is used to bond the fire-resistant layer, allowing it to slowly lose weight during cable combustion and form water-blocking char residue to prevent conductor short circuits. This cable design avoids conductor bridging and short circuits after insulation carbonization and fragmentation, ensuring the integrity of the electrical circuit. The use of a ceramicized silicone rubber heat insulation layer extruded over the insulated cable core significantly reduces conductor heat during fire, preventing conductor melting. It also further enhances flame retardant properties, slows fire spread, and simultaneously reduces the flow path of sprinkler water, comprehensively ensuring the cable meets the comprehensive fire resistance requirements for combustion, impact vibration, and sprinkler systems.

[0026] The special cable for the ship's power system designed in this application meets the requirements for safe return to port and can maintain line integrity for more than 180 minutes under combined conditions of 830℃ flame and vibration spray. It is suitable for critical circuits such as cruise ship electric propulsion systems, emergency lighting, and fire protection facilities. Attached Figure Description

[0027] Figure 1 This is a structural schematic diagram of the marine safety return-to-port cable in this application.

[0028] In the diagram: 1. Conductor; 2. Fire-resistant layer; 3. Insulating layer; 4. Heat-insulating layer; 5. Shielding layer; 6. Sheath layer. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this application clearer, the specific implementation methods of this application are described clearly and completely below. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0030] like Figure 1 As shown, the marine safety return cable designed in this application includes, from the inside out, a conductor 1, a fire-resistant layer 2 disposed on the outer surface of the conductor 1, an insulation layer 3 disposed on the outer surface of the fire-resistant layer 2, a heat insulation layer 4 disposed on the outer surface of the insulation layer 3, a shielding layer 5 disposed on the outer surface of the heat insulation layer 4, and a sheath layer 6 disposed on the outer surface of the shielding layer 5.

[0031] To address the problems of existing conventional cables, such as excessive rigidity of mica tape (leading to increased overlap gaps when the cable bends, making it easy for sprayed water to penetrate the conductor and cause short circuits after combustion) and insufficient temperature resistance of adhesives (conventional silicone adhesives carbonize rapidly above 800℃, losing their bonding strength and causing the mica layer to detach and fail), this application designs a fire-resistant layer 2 formed by a composite wrapping of mica tape and fiberglass tape on the surface of conductor 1. The fire-resistant layer 2 has a three-layer structure, with adjacent layers having different wrapping directions (the three-layer wrapping direction can be left→right→left, or right→left→right). The overlap rate of the mica tape during wrapping is controlled to be no less than 50%. Through the three-layer orthogonal wrapping structure, the overlap coverage of each layer reaches 100%, which can eliminate the penetration path of moisture at high temperatures and prevent short circuits caused by fire extinguishing moisture.

[0032] In some specific embodiments, to reduce the risk of cracking at the lap joints of the mica tape under high-temperature spraying, the unit area weight of the mica tape is 35~45g / m². 2The mica sheet diameter is ≤50μm. To enhance the wrapping adhesion of the refractory layer 2, the glass fiber content in the refractory layer 2 is ≤45%, and the twist coefficient is ≥1200. The lower glass fiber content can reduce the hardness of the strip, while the higher twist coefficient can improve the bending resistance of the strip, making the strip elongation ≥15%, while the elongation of traditional strips is ≤10%.

[0033] In some specific embodiments, to overcome the problem of insufficient temperature resistance of traditional adhesives, this application designs a new adhesive, which, by mass percentage, comprises 48%~52% silicone resin, 28%~32% ceramicized zinc borate, 14%~16% nano-silica, and 4%~6% platinum catalyst. The silicone resin, as the adhesive matrix resin, has a temperature resistance ≥1200℃ and can form a continuous carbon skeleton after combustion, making it difficult to detach. The ceramicized zinc borate material has excellent fire resistance; it can sinter at temperatures above 830℃ to form a ceramic layer with a residual carbon rate ≥60%, which can seal overlap gaps and prevent moisture from entering the conductor and causing a short circuit under high-temperature spraying. Nano-silica can further improve the density of the residual carbon after the adhesive burns, and the overall water permeability of the adhesive is ≤0.1g / (m³). 2 (h). The adhesive designed in this application has a viscosity of 20000±5000cp at 25℃, a coating thickness of 5±0.5μm, and an insulation resistance attenuation rate of <20% under high-temperature spraying.

[0034] The method for preparing the marine safety return-to-port cable of this application includes the following steps: S1. The wire material is sequentially drawn, annealed, and bundled to obtain a single wire filament.

[0035] A 1.2mm copper rod is drawn through a gradually changing aperture die in a small wire drawing machine to produce monofilaments. After passing through an annealing furnace at a high temperature of 600℃, the monofilaments are tin-plated. The annealed monofilaments are then passed online through a 400℃ tin furnace, and after being sized by an eye die at the end of the tin furnace, a tin-plated conductor monofilament is obtained.

[0036] S2. Twist the single wires of the conductor into a conductor, and at the same time wrap the outer surface of the conductor with a fire-resistant layer.

[0037] Several monofilament bundles are twisted into 0.5mm diameter bundles. 2 ~16mm 2 The conductor units are twisted into conductors using a multi-strand (1+6+12+18) configuration. During the conductor twisting process, refractory mica fiberglass tape is simultaneously applied and wrapped, with an overlap rate ≥50%. The three orthogonal wrapping directions are left → right → left. During refractory layer wrapping, the tension is controlled at 0.5 N / mm².

[0038] S3. Perform the first extrusion process by using a high-speed extruder with a screw diameter of φ80mm-φ90mm and a length-to-diameter ratio of 25:1 to coat the outer surface of the refractory layer to form an XLPE insulation layer.

[0039] S4. Perform a second extrusion process, using a high-speed extruder with a screw diameter of φ100mm and a length-to-diameter ratio of 25:1 to extrude a ceramicized silicone rubber heat insulation layer on the outer surface of the insulation layer.

[0040] S5. Perform loose winding treatment, using nickel-plated carbon fiber material to form a shielding layer by winding it onto the outer surface of the insulation layer at a fixed angle and unidirectional gap in a cage winding machine.

[0041] S6. A third extrusion process is performed using a high-speed extruder with a screw diameter of φ100mm and a length-to-diameter ratio of 25:1 to extrude a PO sheath layer onto the outer surface of the shielding layer. This yields a marine safety return-to-port cable. Three types of cables, as shown in the table below, were prepared using the method described above.

[0042]

[0043] Fire resistance performance tests were conducted on three types of cables. The test method was as follows: For cables with an outer diameter ≤20mm, the cable shall be subjected to fire according to the test method of IEC 60331-2, and the cable shall be subjected to impact during the fire supply process, with an interval of 5 minutes. Starting from the 165th minute of the fire impact test, a water spray test shall be added for 15 minutes, and the spray device and test procedure shall be tested according to EN 50200 standard.

[0044] For cables with an outer diameter greater than 20 mm, apply a flame to the cable according to the test method of IEC 60331-1, and subject the cable to an impact during the flame application process, with intervals of 10 minutes. Starting from the 175th minute of the flame impact test, add a water jet test, each time for 5 seconds, with an interval of 60 seconds. The jetting device and test procedure shall be tested according to BS 8491 standard. Flame and impact should continue to be applied during the water jetting.

[0045] The tests showed that all three cables passed the fire resistance test. The cables were not broken down during the 180-minute fire, impact, water spray and water jet tests, meaning that the 2A fuse of the test device did not break and the indicator light did not go out.

[0046] The embodiments of this application have been described in detail above, but this application is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of this application, and these variations still fall within the protection scope of this application.

Claims

1. A marine safety return-to-port cable, characterized in that, From the inside out, it includes a conductor, a fire-resistant layer, an insulating layer, a heat insulation layer, a shielding layer, and a sheath layer. The refractory layer is formed by wrapping mica tape and fiberglass tape around the surface of the conductor. The refractory layer consists of three layers, with adjacent layers wrapped in different directions. The refractory layer is bonded to the surface of the conductor by an adhesive, which is composed of 48%~52% organosilicon resin, 28%~32% ceramicized zinc borate, 14%~16% nano-silica, and 4%~6% platinum catalyst by mass percentage. The mica tape has an overlap rate of not less than 50%, and the mica tape has a unit area weight of 35~45g / m². 2 ; The diameter of the mica strip is less than or equal to 50 μm; The refractory layer contains less than or equal to 45% fiberglass tape and has a twist coefficient greater than or equal to 1200.

2. The marine safety return-to-port cable according to claim 1, characterized in that, The heat insulation layer is composed of ceramicized silicone rubber.

3. The marine safety return-to-port cable according to claim 1, characterized in that, The insulating layer is composed of cross-linked polyethylene.

4. The marine safety return-to-port cable according to claim 1, characterized in that, The shielding layer is woven from nickel-plated carbon fiber monofilaments, and the outer diameter of the nickel-plated carbon fiber monofilaments is not less than 0.11 mm.

5. The marine safety return-to-port cable according to claim 4, characterized in that, The gap between the nickel-plated carbon fiber monofilaments is no greater than the outer diameter of the nickel-plated carbon fiber monofilament.

6. The marine safety return-to-port cable according to claim 1, characterized in that, The sheath layer is composed of polyolefin material with an oxygen index greater than or equal to 35%.

7. A method for preparing a marine safety return-to-port cable according to any one of claims 1 to 6, characterized in that, Includes the following steps: S1. The wire material is sequentially drawn, annealed, and bundled to obtain a single wire filament; S2. Twist the single wires of the conductor into a conductor, and at the same time wrap the outer surface of the conductor with a fire-resistant layer. S3. Perform the first extrusion process to form an insulating layer on the outer surface of the refractory layer; S4. Perform a second extrusion process to form a heat insulation layer on the outer surface of the insulation layer. S5. Perform loose winding treatment to form a shielding layer by winding it around the outer surface of the insulation layer; S6. Perform a third extrusion process to form a sheath layer on the outer surface of the shielding layer, thus obtaining a marine safety return-to-port cable.

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