Wear-resistant high-flame-retardant railway signal cable and preparation method thereof

Abstract

The invention provides a wear-resistant high-flame-retardant railway signal cable and a preparation method, and aims to solve the problems of poor wear resistance and limited flame retardance of the existing cable, the wear-resistant high-flame-retardant railway signal cable comprises a cable core and a protective layer wrapping the cable core, the cable core is formed by twisting insulating single wires, and each insulating single wire comprises an oxygen-free copper conductor, a wear-resistant alloy layer and an insulating layer. The protective layer sequentially comprises a wear-resistant wrapping tape, a heat insulation layer, a shielding layer, an inner sheath, an armor, a flame-retardant oxygen barrier layer and an outer sheath; by optimizing the material and structure of each layer, plating a wear-resistant alloy layer on the surface of the conductor, adding a wear-resistant filler into the insulating layer, adopting a novel flame-retardant material and the like, the wear resistance and flame retardance of the cable are improved, the industrial problem that flame retardance and wear resistance are difficult to consider is solved through material compounding and structural innovation, the process is efficient and environment-friendly, and the cost is low. The requirements of industrial production, fire safety and the like on high performance of the cable are met, the service life and safety of the cable are improved, and the cable has wide market prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of railway signal cables, and in particular to a wear-resistant and highly flame-retardant railway signal cable and a preparation method thereof. Background Art

[0002] In the railway system, signal cables are key components to ensure the safe and efficient operation of trains, and their performance is of vital importance. Currently, the railway industry is developing rapidly, the operating speed is constantly increasing, and the transportation density is continuously increasing, which puts higher requirements on the performance of signal cables.

[0003] The utility model with authorization announcement number CN201438388U discloses an "ultra-flexible railway signal cable", comprising: a cable core, an extruded insulation layer, and a sheath. The cable core is located in the center and is wrapped by an extruded insulation layer. The sheath is located at the outermost layer. A shielding layer is wrapped around the extruded insulation layer. The shielding layer is made of S-shaped self-locking steel strips wrapped around each other in sequence. A copper wire leakage line is arranged longitudinally along the inner wall of the shielding layer. It has good flexibility, easy grounding operation, and resistance to electromagnetic interference. However, the outer skin of the cable of this utility model is easily damaged by friction, which in turn causes the internal circuit to be exposed.

[0004] The utility model with authorization announcement number CN201965951U discloses a high-pulse voltage railway digital signal cable, including an outer sheath and a cable core inside the outer sheath. The cable core is composed of a four-wire group or a twisted pair group with different color codes or an insulated single wire. The insulation structure of the insulated wires in the cable core is a skin-foam-skin structure. The nominal cross-section of the conductor of the insulated wire in the cable core is at least 2.5 square millimeters. This utility model is a new high-voltage pulse railway digital signal cable, which reduces the impedance, DC resistance and attenuation of the cable, and improves the safety and reliability of the track circuit. However, the cable has limited flame retardant properties and is easy to burn and release toxic gases in the event of a fire. It cannot effectively prevent the spread of fire and may cause significant casualties and property losses.

[0005] In summary, existing railway signal cable devices generally have the following disadvantages: 1) Poor wear resistance: Cables need to be frequently moved and dragged, and come into contact with rough surfaces. The outer sheath of ordinary flame-retardant cables is easily damaged by friction, which in turn exposes the internal circuits. 2) Limited flame retardancy: In the event of a fire, it is easy to burn and release toxic gases, which cannot effectively prevent the spread of fire, may cause significant casualties and property losses, and will seriously affect the normal operation of the railway. Summary of the Invention

[0006] The purpose of the present invention is to solve the problems in the prior art and to provide a wear-resistant and highly flame-retardant railway signal cable and a preparation method thereof, which can solve the problems of poor wear resistance and limited flame retardancy.

[0007] To achieve the above objectives, the present invention proposes a wear-resistant and highly flame-retardant railway signal cable and a preparation method, comprising a cable core and a protective layer wrapped around the cable core, wherein the cable core is composed of at least four insulated single wires twisted together, and the insulated single wires are, from the inside to the outside, an oxygen-free copper conductor, a wear-resistant alloy layer, and an insulating layer; the protective layer is wrapped around the outside of the cable core, and the protective layer is, from the inside to the outside, a wear-resistant tape, a thermal insulation layer, an aluminum foil wrapped shielding layer, a tinned copper wire braided shielding layer, an inner sheath layer, an armor layer, a flame-retardant oxygen-isolating layer, and an outer sheath layer.

[0008] Preferably, the at least four insulated single wires are twisted to form a cable core, the twist pitch between the insulated single wires 2 is ≤280 mm, and the tie pitch is ≤30 mm.

[0009] Preferably, the insulating layer is composed of a low-density polyethylene inner layer, a high-density polyethylene insulation layer, and an outer layer from the inside to the outside. The thickness of the low-density polyethylene inner layer is controlled at 0.03 to 0.04 mm, the thickness of the high-density polyethylene insulation layer is controlled at 0.40 to 0.46 mm, and the thickness of the outer layer is controlled at 0.22 to 0.28 mm.

[0010] Preferably, the surface of the oxygen-free copper conductor is uniformly electroplated with a wear-resistant alloy layer.

[0011] Preferably, the insulating layer is formed by simultaneously extruding a low-density polyethylene inner layer, a high-density polyethylene insulating layer and an outer layer using a three-layer co-extrusion process.

[0012] Preferably, the outer skin layer is made of a mixture of a new type of halogen-free flame-retardant polyolefin material and a nano-scale silica wear-resistant filler in a ratio of 7:1.

[0013] Beneficial effects of the present invention: 1) Significant wear resistance: By plating a wear-resistant metal alloy on the conductor surface, adding a wear-resistant filler to the insulation layer, and using a special wear-resistant reinforcing agent to prepare the sheath layer, the cable of the present invention has significantly improved wear resistance, which can meet the requirements of frequent cable movement and friction in industrial production; 2) Excellent flame retardant performance: The inner and outer sheath layers are made of new flame retardant insulation materials, flame retardant oxygen barrier layers and high-efficiency flame retardants, which make the cable have excellent flame retardant performance. It can effectively prevent the spread of fire in the event of a fire and ensure the safety of people and property. 3) Stable electrical performance: The high purity and special treatment of the conductor, the multi-layer co-extrusion process of the insulation layer, and the double-layer structure of the shielding layer ensure that the cable has good electrical insulation and shielding performance and can transmit stably; 4) Good mechanical properties: The special material and structure of the sheath layer give the cable high mechanical strength and flexibility, enabling it to withstand large external impacts and bending, and adapt to complex laying environments.

[0014] The features and advantages of the present invention will be described in detail through embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the insulated single wire structure of the present invention; Figure 2 2 is a schematic diagram of the cable core structure of the present invention; Figure 3 It is a schematic diagram of the overall structure of the present invention.

[0016] Numbers in the figure: 1-cable core; 2-insulated single wire; 3-oxygen-free copper conductor; 4-wear-resistant alloy layer; 5-low-density polyethylene inner layer; 6-high-density polyethylene insulation layer; 7-outer layer; 8-wear-resistant tape; 9-thermal insulation layer; 10-aluminum foil wrapped shielding layer; 11-tinned copper wire braided shielding layer; 12-inner sheath layer; 13-armor layer; 14-flame retardant oxygen insulation layer; 15-outer sheath layer. DETAILED DESCRIPTION

[0017] Example 1: See Figures 1 to 3 The present invention provides a wear-resistant and highly flame-retardant railway signal cable and a preparation method thereof, comprising a cable core 1 and a protective layer wrapping the cable core 1, wherein the cable core 1 is composed of at least four insulated single wires 2 twisted together, such as Figure 1 As shown, the insulated single wire 2 is composed of an oxygen-free copper conductor 3, a wear-resistant alloy layer 4, and an insulating layer from the inside to the outside; Figure 2 As shown, the cable core 1 is composed of at least four insulated single wires 2 twisted together, as shown in FIG. Figure 3 As shown, the protective layer is wrapped around the outside of the cable core 1, and the protective layer is composed of a wear-resistant tape 8, a heat insulation layer 9, an aluminum foil wrapped shielding layer 10, a tinned copper wire braided shielding layer 11, an inner sheath layer 12, an armor layer 13, a flame retardant oxygen isolation layer 14, and an outer sheath layer 15 from the inside to the outside.

[0018] A wear-resistant alloy layer 4 with a thickness of 0.03mm is plated on the surface of the oxygen-free copper conductor 3; low-density polyethylene 5, high-density polyethylene 6 and outer skin layer 7 are extruded by a three-layer co-extrusion process, wherein the thickness of the low-density polyethylene inner skin layer is controlled at 0.03mm, the thickness of the high-density polyethylene insulation layer is controlled at 0.40mm, and the thickness of the outer skin layer is controlled at 0.22mm; the outer skin layer is made of a new halogen-free flame-retardant polyolefin material and a nano-scale silica wear-resistant filler mixed in a ratio of 7:1; the cable core 1 is composed of four insulated single wires 2 twisted together, and then the prepared insulating single wires 2 are twisted in a clockwise direction to form the cable core 1, the twist pitch between the insulating single wires 2 is controlled at 250mm, and the tie pitch is controlled at 20mm , and wrap a layer of polyester wear-resistant tape 8 around the cable core 1; use an elongation polyolefin elastomer material and coat it on the cable core 1 through an extruder to form a 0.5mm thick insulation layer 9; first use a 0.05mm thick aluminum foil wrapped shielding layer 10, and then use a tinned copper wire braided shielding layer 11 on the outer layer; the inner sheath layer 9 uses TPU material and is coated on the cable core 1 through an extruder to form a 0.8mm thick inner sheath layer 12. The inner sheath layer 12 has uniform thickness, smooth surface and is tightly bonded to the cable core 1; the outer sheath layer 15 uses 65 parts of flame-retardant environmentally friendly TPU with a hardness of 80A, 5 parts of modified graphene, and 30 parts of high-efficiency flame retardant to fully mix, and the thickness of the outer sheath 15 is controlled at 2.0mm.

[0019] In this embodiment, the outer layer 7 is made of a new type of halogen-free flame-retardant polyolefin material and a nano-scale silica wear-resistant filler mixed in a ratio of 7:1. This ratio allows the cable to maintain good wear resistance while also having excellent flame retardant properties, which can effectively meet the basic requirements for cable wear resistance and flame retardancy in general railway signal transmission scenarios.

[0020] A method for preparing a wear-resistant and highly flame-retardant railway signal cable comprises the following steps: a) Conductor preparation: An oxygen-free copper conductor 3 is used to form a single wire of the required specifications using a wire drawing machine, and then a wear-resistant alloy layer 4 is plated on the surface of the oxygen-free copper conductor 3; b) Preparation of the insulation layer: low-density polyethylene 5, high-density polyethylene 6 and an outer skin layer 7 are extruded and formed. The outer skin layer 7 is made of a new halogen-free flame-retardant polyolefin material mixed with a wear-resistant filler to form a three-layer insulation layer; c) Twisting into cable: twisting the prepared insulated single wires 2 in a structural order to form a cable core 1, selecting a twisting pitch for cabling, and wrapping the cable core 1 with a wear-resistant tape 8; d) Preparation of thermal insulation layer: a polyolefin elastomer material with high elongation is used and coated on the cable core 1 through an extruder to form a thermal insulation layer 9; e) Shielding layer preparation: A double-layer shielding structure is used, with an inner layer of aluminum foil wrapped shielding layer 10 and an outer layer of tinned copper wire braided shielding layer 11; f) Preparation of inner sheath layer: TPU material is used and coated on the cable core 1 through an extruder to form an inner sheath layer 12. The inner sheath layer 12 has uniform thickness, smooth surface and is tightly bonded to the cable core 1; g) Armour layer preparation: Double-layer galvanised steel strips are used for wrapping, with the steel strips fitting tightly together; h) Preparation of flame retardant oxygen-insulating layer: A glass fiber oxygen-insulating layer is wrapped around the armor layer 13; i) Preparation of outer sheath layer: A wear-resistant and flame-retardant composite material is used and coated on the outside of the armor layer 13 through an extruder to form an outer sheath layer 15.

[0021] Example 2: This embodiment is basically the same as Example 1, except that: the cable core 1 is composed of five insulated single wires 2 twisted together, the thickness of the outer skin layer of the insulating layer of the insulating single wire 2 is controlled at 0.25 mm, and the outer skin layer is made of a new halogen-free flame-retardant polyolefin material and a nano-scale silica wear-resistant filler mixed in a ratio of 2:1; at the same time, the twisting pitch between the insulating single wires 2 is controlled at 280 mm, and the cable tie pitch is controlled at 30 mm.

[0022] In this embodiment, the thickness of the outer layer 7 is increased to 0.25 mm, and the proportion of wear-resistant filler is increased, which further improves the wear resistance of the cable, increases the twist pitch, and increases the tie pitch accordingly. This design makes the cable more flexible to a certain extent and is suitable for railway curves, switch areas, and some special locations where cables need to be frequently moved and bent, such as signal cable laying in stations.

[0023] Example 3: This embodiment is basically the same as Example 1, except that: the cable core 1 is composed of six insulated single wires 2 twisted together, the thickness of the outer skin layer 7 of the insulation layer of the insulated single wire 2 is controlled to be 0.28 mm, and the outer skin layer 7 is made of a new halogen-free flame-retardant polyolefin material and a nano-scale silica wear-resistant filler mixed in a ratio of 4:1; in addition, the thickness of the flame-retardant oxygen-isolating layer 14 is increased to 0.5 mm.

[0024] In this embodiment, the thickness of the outer layer 7 reaches 0.28 mm, and the thickness of the flame retardant oxygen insulation layer 14 is increased to 0.5 mm. At the same time, the proportion of wear-resistant filler in the outer layer is further increased. These improvements enable the cable to more effectively prevent the spread of fire when facing a fire, provide a higher level of flame retardant protection, and reduce the risk of damage to railway facilities and personnel caused by fire. It is suitable for use in some railway sections with complex geological conditions and potential physical damage risks, such as railway lines passing through mountains, bridges and other special structures, to ensure the continuity of signal transmission and the safety of railway transportation.

[0025] Working principle: When the railway signal cable of the present invention is working, the signal is transmitted through the oxygen-free copper conductor 3. The wear-resistant alloy layer 4 on the surface of the oxygen-free copper conductor 3 can effectively reduce the wear of the conductor during frequent movement and friction, thereby extending the service life of the conductor; the insulation layer adopts a three-layer co-extrusion process, in which the low-density polyethylene inner layer is tightly combined with the conductor to provide preliminary insulation protection, the high-density polyethylene insulation layer has good insulation performance, and can effectively prevent corona discharge and electrical breakdown, and the new halogen-free flame-retardant polyolefin material and nano-scale silica wear-resistant filler in the outer layer improve the wear resistance and flame retardancy of the insulation layer; the protective layer outside the cable core 1 performs different functions in turn: the wear-resistant wrapping tape 8 provides additional wear-resistant protection for the entire cable, reducing the impact of external friction on the internal cable core; the thermal insulation layer 9 can effectively prevent The double-layer shielding structure, namely the aluminum foil wrapped shielding layer 10 and the tinned copper wire braided shielding layer 11, can effectively shield external electromagnetic interference and ensure the stability of signal transmission; the inner sheath layer 12 adopts TPU material with good flexibility and mechanical strength to further protect the internal structure and make the layers tightly combined; the double-layer galvanized steel tape wrapped structure of the armor layer 13 can withstand large external force impact and mechanical damage, and protect the integrity of the internal structure of the cable; the glass fiber material of the flame retardant oxygen insulation layer 14 can effectively prevent oxygen from entering and suppress the spread of fire; the wear-resistant flame retardant composite material of the outer sheath layer 15 serves as the last line of defense of the cable, preventing external flame intrusion and external wear, and ensuring the safe operation of the cable in complex environments.

[0026] The above embodiments are intended to illustrate the present invention, not to limit the present invention. Any solution that is a simple transformation of the present invention falls within the protection scope of the present invention.

Claims

1. A wear-resistant and highly flame-retardant railway signal cable, comprising a cable core (1) and a protective layer wrapping the cable core (1), characterized in that: The cable core (1) is composed of at least four insulated single wires (2) twisted together, wherein the insulated single wires (2) are, from the inside to the outside, an oxygen-free copper conductor (3), a wear-resistant alloy layer (4), and an insulation layer; the protective layer is wrapped around the outside of the cable core (1), and the protective layer is, from the inside to the outside, a wear-resistant tape (8), a heat insulation layer (9), an aluminum foil wrapped shielding layer (10), a tinned copper wire braided shielding layer (11), an inner sheath layer (12), an armor layer (13), a flame-retardant oxygen-isolating layer (14), and an outer sheath layer (15).

2. The wear-resistant and highly flame-retardant railway signal cable according to claim 1, characterized in that: The at least four insulated single wires (2) are twisted to form a cable core (1); the twisting pitch between the insulated single wires (2) is ≤280 mm, and the tie pitch is ≤30 mm.

3. The wear-resistant and highly flame-retardant railway signal cable according to claim 1, characterized in that: The insulating layers are respectively a low-density polyethylene inner layer (5), a high-density polyethylene insulating layer (6), and an outer layer (7) from the inside to the outside. The thickness of the low-density polyethylene inner layer (5) is controlled to be 0.03-0.04 mm, the thickness of the high-density polyethylene insulating layer (6) is controlled to be 0.40-0.46 mm, and the thickness of the outer layer (7) is controlled to be 0.22-0.28 mm.

4. The wear-resistant and highly flame-retardant railway signal cable according to claim 1, characterized in that: The wear-resistant alloy layer (4) has a thickness of 0.02 to 0.04 mm, the heat insulation layer (9) has a thickness of 0.7 to 0.9 mm, the inner sheath layer (12) has a thickness of 1.3 to 1.5 mm, and the outer sheath layer (15) has a thickness of 1.9 to 2.0 mm.

5. A method for preparing a wear-resistant and highly flame-retardant railway signal cable, characterized in that: The following steps are involved: a) Conductor preparation: using an oxygen-free copper conductor (3), forming a single wire of required specifications by a wire drawing machine, and then coating the surface of the oxygen-free copper conductor (3) with a wear-resistant alloy layer (4); b) Preparation of the insulation layer: low-density polyethylene (5), high-density polyethylene (6) and an outer skin layer (7) are extruded and formed, wherein the outer skin layer (7) is made of a new type of halogen-free flame-retardant polyolefin material mixed with a wear-resistant filler to form a three-layer insulation layer; c) Twisting into a cable: twisting the prepared insulated single wires (2) in a structural order to form a cable core (1), selecting a twisting pitch for cabling, and wrapping the cable core (1) with a wear-resistant tape (8); d) Preparation of thermal insulation layer: using a polyolefin elastomer material with elongation, and coating it on the cable core (1) through an extruder to form a thermal insulation layer (9); e) Shielding layer preparation: A double-layer shielding structure is used, with an inner layer of aluminum foil wrapped shielding layer (10) and an outer layer of tinned copper wire braided shielding layer (11); f) Preparation of the inner sheath layer: using TPU material, coating the cable core (1) with an extruder to form an inner sheath layer (12); the inner sheath layer (12) has a uniform thickness, a smooth surface, and is tightly bonded to the cable core (1); g) Armour layer preparation: Double-layer galvanised steel strips are used for wrapping, with the steel strips fitting tightly together; h) Preparation of flame retardant oxygen-insulating layer: a glass fiber oxygen-insulating layer is wrapped around the armor layer (13); i) Preparation of outer sheath layer: A wear-resistant and flame-retardant composite material is used and coated on the outside of the armor layer (13) through an extruder to form an outer sheath layer (15).

6. The method for preparing a wear-resistant and highly flame-retardant railway signal cable according to claim 5, wherein: The surface of the oxygen-free copper conductor (3) is uniformly electroplated with a wear-resistant alloy layer (4).

7. The method for preparing a wear-resistant and highly flame-retardant railway signal cable according to claim 5, wherein: The insulating layer is formed by simultaneously extruding a low-density polyethylene inner layer (5), a high-density polyethylene insulating layer (6) and an outer layer (7) using a three-layer co-extrusion process.

8. A method for preparing a wear-resistant and highly flame-retardant railway signal cable according to any one of claims 5 to 7, characterized in that: The outer skin layer (7) is made of a new type of halogen-free flame-retardant polyolefin material and a nano-scale silica wear-resistant filler mixed in a ratio of 7:1.

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