Flame retardant special power cable

Abstract

The utility model relates to the field of cable technology, and specifically to a flame-retardant special power cable, including a core, a filling layer, a wrapping, a shielding layer, an inner lining layer and a steel wire armor layer. The steel wire armor layer is provided with a flame-retardant layer filled with magnesium hydroxide filler on the outside, and a plurality of braided fiber ropes are provided inside the flame-retardant layer, which are laid along the cable axial direction and evenly arranged along the cable circumference. The outer side of the flame-retardant layer is coated with a ceramic silicone layer, and the outer side of the ceramic silicone layer is extruded with an outer sheath; by arranging the magnesium hydroxide filler on the outer side of the steel wire armor layer, the functional layer is prevented from being damaged due to bursting, and at the same time, a plurality of braided fiber ropes are arranged in the flame-retardant layer, and a large number of braiding gaps formed inside the braided fiber ropes due to braiding can form an exhaust pressure relief channel, and water vapor can flow through the braiding gaps and finally be discharged through the two ends of the cable, so as to avoid bursting due to excessive pressure inside the cable.

Description

Technical Field

[0001] The utility model relates to the technical field of cables, in particular to a flame-retardant special power cable. Background Art

[0002] Special cables refer to cables used for specific purposes in specific occasions. They have special requirements for the performance of the cables, such as high temperature resistance, low temperature resistance, corrosion resistance, rat and ant resistance, oil resistance, impact resistance, torsion resistance, fatigue resistance, etc. They are widely used in industries and fields such as automobiles, ships, aircraft, coal machines, industrial robots, and nuclear power plants. Taking steel wire armored power cables as an example, they have high tensile strength and the ability to resist external forces. They are suitable for short-distance overhead laying or vertical and vertical laying. They are used in laying paths with large undulating spans. In order to improve the flame retardant properties of steel wire armored cables, mineral flame retardant fillers are filled inside the cables. Among them, the most widely used filler is magnesium hydroxide, which releases bound water when heated, absorbs a large amount of heat, reduces the cable temperature, and the magnesium oxide formed by decomposition is a good refractory material.

[0003] The magnesium hydroxide fillers of the commonly used flame-retardant cables are filled in the gaps of the wire core, and the outside is also wrapped with a sheath, a shielding layer, a water-blocking layer and other functional layers to prevent the discharge of water vapor. As a result, when the cable is burned by open flames, the water vapor discharge channel of the magnesium hydroxide filler due to thermal decomposition is blocked, resulting in high internal pressure of the cable and prone to bursting. Utility Model Content

[0004] In view of the technical problems existing in the mineral flame retardant filled power cable in the prior art, the first aspect of the utility model proposes a flame retardant special power cable, comprising:

[0005] Multiple wire cores arranged tangentially in pairs;

[0006] A filling layer is filled in the gaps between the plurality of wire cores and is wrapped by the wrapping layer to form a circular cross-sectional shape;

[0007] The outer side of the wrapping layer is coated with a shielding layer and an inner lining layer in sequence, and the outer side of the inner lining layer is provided with a steel wire armor layer formed by twisting a plurality of steel wires;

[0008] The outer side of the steel wire armor layer is provided with a flame retardant layer filled with magnesium hydroxide filler, and the flame retardant layer is configured to be able to decompose and absorb heat when burning. The interior of the flame retardant layer is provided with a plurality of braided fiber ropes laid along the cable axial direction and evenly arranged along the cable circumference. When the flame retardant layer is decomposed by heat, an exhaust channel for pressure relief is provided;

[0009] The outer side of the flame retardant layer is coated with a ceramic silicone layer, and the ceramic silicone layer is configured to harden into a ceramic fireproof shell when burning;

[0010] An outer sheath is extruded on the outer side of the ceramic silicone layer.

[0011] Preferably, the filling thickness of the flame retardant layer is 5.0-8.0 mm, and the ratio of the filling thickness of the flame retardant layer to the diameter of the braided fiber rope is 2:1.

[0012] Preferably, the number of braided strands of the braided fiber rope is not less than 4, and the number of monofilaments in each strand is not less than 8.

[0013] Preferably, the braided fiber rope comprises a glass fiber braided rope.

[0014] Preferably, the wire core comprises a conductor and an inner sheath extruded outside the conductor, and the conductor is made of a plurality of annealed copper wires twisted in a 1+6+12 manner.

[0015] Preferably, the inner sheath is configured as a three-layer co-extruded layer including a conductor shielding layer, an insulating layer, and an insulating shielding layer.

[0016] Preferably, the conductor shielding layer and the insulating shielding layer are both semi-conductive polyolefin shielding layers.

[0017] Preferably, the wrapping layer is formed by wrapping a non-woven fabric tape, the number of wrapping layers is two, and the wrapping overlap rate is 50%.

[0018] Preferably, the inner lining layer is formed by extrusion of polytetrafluoroethylene material, and the thickness of the extrusion is 2.0-3.0 mm.

[0019] Compared with the prior art, the flame-retardant special power cable proposed by the utility model has the following significant beneficial effects:

[0020] 1. By arranging the magnesium hydroxide filler on the outside of the steel wire armor layer, the functional layers such as the wrapping layer, the shielding layer, and the steel wire armor layer are all located on the inside of the flame retardant layer to avoid damage to the functional layer due to explosion. At the same time, multiple braided fiber ropes are arranged in the flame retardant layer. The large number of braided gaps formed inside the braided fiber ropes due to braiding can form an exhaust pressure relief channel. Water vapor can flow through the braided gaps of the braided fiber ropes and finally be discharged through both ends of the cable to avoid the phenomenon of bursting due to excessive pressure inside the cable.

[0021] 2. The braided fiber rope is a glass fiber braided rope. The thicker flame retardant layer and the glass fiber braided rope can both play a heat insulation role, providing heat insulation protection for the steel wire armor layer to prevent the steel wire from being heated and reduced in strength. At the same time, the glass fiber braided rope can increase the tensile strength of the cable;

[0022] 3. The outer side of the flame retardant layer is coated with a ceramic silicone layer. When the cable burns, the ceramic silicone layer 9 can harden into a ceramic fireproof shell during combustion to prevent the spread of fire. At the same time, the hard ceramic shell can fix the magnesium hydroxide filling to prevent the magnesium hydroxide filling from falling off, maintain the integrity of the cable, and improve the power transmission time of the cable when burning. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are not intended to be drawn to scale. In the accompanying drawings, each identical or approximately identical component shown in each figure may be represented by the same reference numeral. For clarity, not every component is labeled in each figure. Now, embodiments of various aspects of the utility model will be described by way of example and with reference to the accompanying drawings.

[0024] Figure 1 It is a structural schematic diagram of the flame-retardant special power cable shown in the utility model.

[0025] Figure 2 It is a schematic diagram of the cross-sectional structure of the flame-retardant special power cable shown in the utility model.

[0026] Figure 3 It is a schematic diagram of a state in which a braided fiber rope in a flame-retardant special power cable shown in the utility model is covered by a flame-retardant layer.

[0027] In the figure: 1. wire core; 11. conductor; 12. inner sheath; 2. filling layer; 3. wrapping layer; 4. shielding layer; 5. inner lining layer; 6. steel wire armor layer; 7. flame retardant layer; 8. braided fiber rope; 9. ceramic silicone layer; 10. outer sheath. DETAILED DESCRIPTION

[0028] In order to better understand the technical content of the present invention, specific embodiments are described below in conjunction with the accompanying drawings.

[0029] At present, the magnesium hydroxide fillers of flame-retardant cables are filled in the gaps of the wire core, and the outer side is also wrapped with a sheath, a shielding layer, a water-blocking layer and other functional layers that hinder the discharge of water vapor. As a result, when the cable is burned by an open flame, the water vapor discharge channel of the magnesium hydroxide filler is blocked by thermal decomposition, resulting in high internal pressure of the cable and easy bursting. Therefore, how to solve the water vapor discharge of the magnesium hydroxide filler during combustion is an urgent problem to be solved.

[0030] Combination Figure 1-Figure 3 As shown, the flame-retardant special power cable of the embodiment of the utility model includes a core 1, a filling layer 2, a wrapping layer 3, a shielding layer 4, an inner lining layer 5, a steel wire armor layer 6, a flame-retardant layer 7 and an outer sheath 10.

[0031] The multiple wire cores 1 are arranged in pairs tangentially, the filling layer 2 is filled in the gaps between the multiple wire cores 1, and is wrapped and solidified by the wrapping layer 3 to form a circular cross-sectional shape.

[0032] Among them, the core 1 includes a conductor 11 and an inner sheath 12 extruded on the outside of the conductor 11. The conductor 11 is made of several strands of annealed copper wires twisted in a 1+6+12 manner. The inner sheath 12 is configured as a three-layer co-extruded layer including a conductor shielding layer, an insulating layer, and an insulating shielding layer. The conductor shielding layer and the insulating shielding layer are both semi-conductive polyolefin shielding layers, and the insulating layer is made of cross-linked polyethylene.

[0033] In a specific embodiment, the filling layer 2 is filled with water-blocking yarn to play a water-blocking role, and the wrapping layer 3 is wrapped with a non-woven fabric tape, and the number of wrapping layers is two, and the wrapping overlap rate is 50%.

[0034] Furthermore, the shielding layer 4, the inner lining layer 5 and the steel wire armor layer 6 are sequentially coated on the outside of the winding layer 3, wherein the shielding layer 4 is a copper tape wrapped shielding layer, specifically a double-layer copper tape gap winding, the winding overlap rate is greater than 25%, and the copper tape thickness is 0.1mm, so that the cable has a good electromagnetic shielding effect, the inner lining layer 5 is extruded and formed by polytetrafluoroethylene material, and the extrusion thickness is 2.0-3.0mm, which plays the role of isolating the steel wire armor layer 6 to avoid the steel wire armor layer 6 causing wear to the shielding layer 4 when the cable is laid and dragged, and the steel wire armor layer 6 is formed by twisting multiple steel wires on the outside of the inner lining layer 5.

[0035] Combination Figure 1 and Figure 2 As shown, a flame retardant layer 7 formed by filling with magnesium hydroxide filler is provided on the outside of the steel wire armor layer 6, which is used to improve the flame retardant performance of the cable, and the flame retardant layer 7 is located on the outside of the functional layers such as the sheathing layer 3, the shielding layer 4, and the steel wire armor layer 6 to avoid damage to the functional layers due to explosion. Furthermore, the inside of the flame retardant layer 7 is provided with a plurality of braided fiber ropes 8 laid along the axial direction of the cable and evenly arranged along the circumference of the cable, providing an exhaust and pressure relief channel for the decomposition of the flame retardant layer 7.

[0036] In this way, since the magnesium hydroxide filler can decompose and absorb heat when burning, the cable temperature can be reduced, thereby improving the flame retardant properties of the cable. When the magnesium hydroxide filler decomposes, a large amount of water vapor will be generated, and the large number of weaving gaps formed inside the braided fiber rope 8 due to weaving can form an exhaust and pressure relief channel. The water vapor can flow through the weaving gaps of the braided fiber rope 8 and finally be discharged through both ends of the cable, thereby avoiding the cable from bursting due to excessive pressure inside.

[0037] In an optional embodiment, the number of braided fiber ropes 8 is not less than 4, and each monofilament is not less than 8. By increasing the number of braided roots and strands, more braiding gaps can be created, thereby improving the ability to exhaust and relieve air pressure.

[0038] Furthermore, the filling thickness of the flame retardant layer 7 is 5.0-8.0 mm, and the ratio of the filling thickness of the flame retardant layer 7 to the diameter of the braided fiber rope 8 is 2:1, so that the braided fiber rope 8 can be completely wrapped by the flame retardant layer 7, avoiding gaps between the braided fiber ropes 8 that cause the magnesium hydroxide filler to flow, thereby maintaining the uniformity of the magnesium hydroxide filler filling.

[0039] In an optional embodiment, the filling thickness of the flame retardant layer 7 is preferably 8.0 mm, and the braided fiber rope 8 is a glass fiber braided rope. The thicker flame retardant layer 7 and the glass fiber braided rope can both have a heat insulation effect, providing heat insulation protection for the steel wire armor layer 6 to prevent the steel wire from being heated and then being reduced in strength. At the same time, the glass fiber braided rope can increase the tensile strength of the cable.

[0040] Combination Figure 1 and Figure 2 As shown, the outer side of the flame retardant layer 7 is coated with a ceramic silicone layer 9. When the cable burns, the ceramic silicone layer 9 can harden into a ceramic fireproof shell during combustion to prevent the fire from spreading. At the same time, the hard ceramic shell can fix the magnesium hydroxide filling to prevent the magnesium hydroxide filling from falling off, maintain the integrity of the cable, and increase the power transmission time of the cable when burning.

[0041] Combination Figure 1 and Figure 2 As shown, an outer sheath 10 is extruded on the outer side of the ceramic silicone layer 9. Specifically, the outer sheath 10 is extruded and formed by extrusion of a flame-retardant polyolefin material, which has good flame-retardant properties.

[0042] Combination Figure 1-3 As shown, the flame-retardant special power cable proposed by the present invention has an exemplary manufacturing process comprising the following steps:

[0043] Step S1: Making the wire core:

[0044] 1.1. Using a stranding machine, a plurality of copper wires are stranded in a 1+6+12 manner to form a conductor 11 having a circular cross-section.

[0045] 1.2. Using an extruder to simultaneously extrude a conductor shielding layer, an insulating layer, and an insulating shielding layer on the outside of the conductor 11, and forming an inner sheath 12 after cooling;

[0046] Step S2: making a cable core:

[0047] 2.1. Arrange multiple strands of wire cores 1 tangentially, and fill the cut seam with water-blocking rope to form a filling layer 2. Then, use a wrapping machine and a non-woven fabric tape to wrap the wire core 1 and the filling layer 2, and wrap and solidify them into a circular cross-section;

[0048] 2.2. Using a wrapping machine and copper tape to wrap around the outer side of the wrapping layer 3 to form a shielding layer 4;

[0049] 2.3. Use an extruder to extrude the inner lining layer 5 on the outside of the shielding layer 4

[0050] Step S3, making an armor layer, using a stranding machine and using multiple strands of steel wire to strand on the outer side of the inner lining layer 5 to form a steel wire armor layer 6;

[0051] Step S4: Making a flame retardant layer

[0052] 4.1. First, a plurality of braided fiber ropes 8 are evenly laid on the outside of the steel wire armor layer 6 along the cable, and the laying direction of the braided fiber ropes 8 is consistent with the axial direction of the cable. Then, a filling machine is used to fill the outside of the steel wire armor layer 6 with magnesium hydroxide filler, and the braided fiber ropes 8 are completely covered to form a flame retardant layer.

[0053] 4.2. While filling the magnesium hydroxide filler, ceramic silicone rubber is extruded on the outer side of the flame retardant layer 7 to fix the magnesium hydroxide filler, and a ceramic silicone layer 9 is formed after cooling;

[0054] Step S5, making an outer sheath, using an extruder to extrude flame-retardant polyolefin on the outer side of the ceramic silicone layer 9, and forming the outer sheath 10 after cooling.

[0055] In combination with the above embodiments, the flame-retardant special power cable proposed by the utility model arranges magnesium hydroxide filler on the outside of the steel wire armor layer 6, so that the functional layers such as the sheath 3, the shielding layer 4, the steel wire armor layer 6 are all located on the inside of the flame-retardant layer 7, so as to avoid damage to the functional layers due to explosion. At the same time, a plurality of braided fiber ropes 8 are arranged in the flame-retardant layer 7. The large number of braiding gaps formed inside the braided fiber ropes 8 due to weaving can form an exhaust and pressure relief channel. Water vapor can flow through the braiding gaps of the braided fiber ropes 8 and finally be discharged through both ends of the cable, so as to avoid bursting of the cable due to excessive pressure inside.

[0056] At the same time, the outer side of the flame retardant layer 7 is coated with a ceramic silicone layer 9. When the cable burns, the ceramic silicone layer 9 can harden into a ceramic fireproof shell during combustion to prevent the fire from spreading. At the same time, the hard ceramic shell can fix the magnesium hydroxide filling to prevent the magnesium hydroxide filling from falling off, maintain the integrity of the cable, and improve the power transmission time of the cable when burning.

[0057] Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. A person with ordinary knowledge in the technical field to which the present invention belongs may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the definition of the claims.

Claims

1. A flame-retardant special power cable, characterized in that: include: A plurality of wire cores (1) arranged tangentially to each other; A filling layer (2) is filled in the gaps between the plurality of wire cores (1) and is wrapped by the wrapping layer (3) to form a circular cross-sectional shape; The outer side of the wrapping layer (3) is coated with a shielding layer (4) and an inner lining layer (5) in sequence, and the outer side of the inner lining layer (5) is provided with a steel wire armor layer (6) formed by twisting a plurality of steel wires; The outer side of the steel wire armor layer (6) is provided with a flame retardant layer (7) filled with magnesium hydroxide filler, and the flame retardant layer (7) is configured to be able to decompose and absorb heat when burning. The interior of the flame retardant layer (7) is provided with a plurality of braided fiber ropes (8) laid along the cable axial direction and evenly arranged along the cable circumference. When the flame retardant layer (7) is decomposed by heat, an exhaust channel for pressure relief is provided; The outer side of the flame retardant layer (7) is coated with a ceramic silicone layer (9), and the ceramic silicone layer (9) is configured to be hardened into a ceramic fireproof shell when burning; An outer sheath (10) is extruded on the outer side of the ceramicized silica gel layer (9).

2. The flame-retardant special power cable according to claim 1, characterized in that: The filling thickness of the flame retardant layer (7) is 5.0-8.0 mm, and the ratio of the filling thickness of the flame retardant layer (7) to the diameter of the braided fiber rope (8) is 2:

1.

3. The flame-retardant special power cable according to claim 1, characterized in that: The number of braided strands of the braided fiber rope (8) is not less than 4, and the number of monofilaments in each strand is not less than 8.

4. The flame-retardant special power cable according to claim 1, characterized in that: The braided fiber rope (8) comprises a glass fiber braided rope.

5. The flame-retardant special power cable according to claim 1, characterized in that: The wire core (1) comprises a conductor (11) and an inner sheath (12) extruded outside the conductor (11); the conductor (11) is a plurality of annealed copper wires twisted in a 1+6+12 manner.

6. The flame-retardant special power cable according to claim 5, characterized in that: The inner sheath (12) is configured as a three-layer co-extruded layer comprising a conductor shielding layer, an insulating layer, and an insulating shielding layer.

7. The flame-retardant special power cable according to claim 6, characterized in that: The conductor shielding layer and the insulating shielding layer are both semi-conductive polyolefin shielding layers.

8. The flame-retardant special power cable according to claim 1, characterized in that: The wrapping layer (3) is formed by wrapping a non-woven fabric tape, the number of wrapping layers is two, and the wrapping overlap rate is 50%.

9. The flame-retardant special power cable according to claim 1, characterized in that: The inner lining layer (5) is formed by extrusion of polytetrafluoroethylene material, and the thickness of the extrusion is 2.0-3.0 mm.

Images