Environmentally friendly high-temperature resistant and fireproof special cable and preparation method

Abstract

The present invention relates to the technical field of cable wires, and provides an environmentally friendly high-temperature resistant and fireproof special cable and a preparation method thereof, including a cable core, a shielding layer and an outer sheath. The conducting core includes a plurality of mutually twisted wires, and a first insulating layer and a second insulating layer are coated on the outer side of the wires from the inside to the outside. A through hole is axially formed in the second insulating layer, and a fireproof strip is arranged in the through hole. The fireproof strip is filled with a fireproof filler, and the fireproof filler can move axially in the fireproof strip. By arranging the fireproof strip in the second insulating layer, when a part of the area is burned through, the fireproof filler in the fireproof strip will flow towards the fire area and gradually gather in the fire area to form a relatively thick fireproof barrier. Compared with the existing fixed spraying method, the movable fireproof filler can gather from the non-fire area to the fire area, forming a thicker barrier in the area where fireproof is required, so as to achieve a better fireproof effect.

Description

Technical Field

[0001] The present invention relates to the technical field of wire and cable, and more particularly to an environmentally friendly high-temperature resistant and fireproof special cable and a preparation method thereof. Background Art

[0002] Fireproof special cables have the characteristics of high temperature resistance, flame retardancy, low smoke, etc., and play a crucial role in fires. They can maintain the continuity of the circuit, support key safety systems such as fire-fighting equipment, emergency lighting, alarm systems, and evacuation indicators, and buy precious time for personnel evacuation and fire-fighting and rescue. At the same time, fireproof cables can also reduce the damage of fires to electrical systems and reduce the economic losses caused by fires.

[0003] The fire-resistant expansion material in fireproof cables is a key fire safety material. It can rapidly expand during a fire to form a dense fireproof barrier, effectively preventing the spread of fire and the diffusion of smoke. Currently, such materials are usually sprayed or filled between the outer sheath or hierarchical structures. When a fire occurs, only the materials in the local area in contact with the flame will expand, and the remaining fireproof materials cannot play a role. Although it plays a blocking role to a certain extent, due to the limited thickness of the fireproof barrier formed by it (generally a few millimeters to more than ten millimeters), the protection time is relatively short. Summary of the Invention

[0004] In view of the defects existing in the prior art, a first aspect of the present invention provides an environmentally friendly high-temperature resistant and fireproof special cable, comprising:

[0005] A cable core, comprising a conductor core and a filling rope that are twisted together, and the conductor core and the filling rope are wound by a composite wrapping layer to form a cable core with a circular cross-section;

[0006] A shielding layer, woven and coated on the outside of the composite wrapping layer;

[0007] An outer sheath, coated on the outside of the shielding layer;

[0008] Wherein, the conductor core includes a plurality of conductors twisted together, and a first insulating layer and a second insulating layer coated on the outside of the conductors from the inside to the outside. A through hole is axially formed in the second insulating layer, a fireproof strip is arranged in the through hole, the fireproof strip is filled with a fireproof filling, and the fireproof filling can move axially in the fireproof strip.

[0009] Preferably, the fireproof strip is provided with a plurality of bonding segments along the length direction, there is a cavity between any two adjacent bonding segments, both ends of the cavity are sealed by the bonding segments, and each cavity is filled with the fireproof filling.

[0010] Preferably, the proportion of the fireproof filling in each of the cavities is between 1 / 2 and 2 / 3.

[0011] Preferably, the distance between any two adjacent bonding segments is set to 50 cm to 100 cm.

[0012] Preferably, the fireproof filling includes a fireproof expanding filling paste, and the space in the cavity other than the fireproof filling is filled with carbon dioxide or air.

[0013] Preferably, a protruding portion is provided on the outer sidewall of the second insulating layer, and the protruding portions on any two adjacent second insulating layers are both at the stranding center.

[0014] Preferably, the number of the fireproof strips distributed on one side close to the protruding portion in the second insulating layer is less than the number of the fireproof strips distributed on the other side.

[0015] Preferably, the filling rope includes a fiberglass rope or a mineral fiber rope.

[0016] Preferably, the composite wrapping layer includes a heat-insulating wrapping layer and a heat-radiation isolation layer that are wrapped in sequence from the inside to the outside, and the wrapping directions of the heat-insulating wrapping layer and the heat-radiation isolation layer are opposite.

[0017] Preferably, the heat-insulating wrapping layer includes a mica wrapping tape, and the heat-radiation isolation layer includes an aluminum foil or an aluminized foil.

[0018] The second aspect of the present invention provides a method for preparing an environmentally friendly high-temperature resistant and fireproof special cable, including the following steps:

[0019] Step 1, preparing a cable core:

[0020] Step 1.1, preparing a conductor core: Using a stranding machine to strand multiple wires with each other to form a conductor, sorting the conductor and multiple fireproof strips at preset positions, and using an extruder to extrude a first insulating layer and a second insulating layer on the outer sides of the conductor and the fireproof strips in a double-layer co-extrusion manner to form a conductor core;

[0021] Step 1.2, preparing a filling rope: Using a braiding machine to braid fiberglass or mineral fiber into a rope body;

[0022] Step 1.3, stranding into a cable: Stranding the prepared conductor cores with each other, filling a filling rope in the gaps outside the conductor cores, positively wrapping a heat-insulating wrapping layer on the outer sides of the conductor cores and the filling rope, and then reversely wrapping a heat-radiation isolation layer on the outer side of the heat-insulating wrapping layer to form a cable core with a circular cross-section, and the heat-insulating wrapping layer and the heat-radiation isolation layer form a composite wrapping layer;

[0023] Step 2, preparing a shielding layer: using a braiding machine to weave a copper mesh on the outside of the composite wrapping layer, and making the braiding density of the copper mesh greater than 85%, to form a shielding layer on the outside of the composite wrapping layer;

[0024] Step 3, preparing an outer sheath: using an extruder to extrude an insulating material to cover the outer side of the shielding layer to form an outer sheath;

[0025] In step 1.1, the fire-retardant strip is preliminarily formed into a hollow tube by an extruder. After the tube is formed, a fire-retardant filler and a gas are periodically and quantitatively filled into the tube. After the fire-retardant filler is filled in each cycle, the tube is extruded according to a preset length to form a bonding section on the tube, and the filled fire-retardant filler and gas are sealed in the tube to form the fire-retardant strip.

[0026] Compared with the prior art, the environmentally friendly, high temperature resistant and fireproof special cable of the present invention has the following significant advantages:

[0027] The environmentally friendly, high-temperature resistant and fireproof special cable of the present invention is provided with a fire-blocking strip in the second insulating layer. When a part of the area is burned through, the fire-blocking filler in the fire-blocking strip will flow toward the fire area, and gradually gather in the fire area to form a relatively thick fire-blocking barrier. Compared with the existing fixed spraying method, the movable fire-blocking filler can gather from the non-fire area to the fire area, forming a thicker barrier in the area where fire blocking is required, thereby achieving a better fire-blocking effect, and buying more time for emergency disposal and evacuation when fire / danger occurs. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings are not intended to be drawn to scale. In the accompanying drawings, each identical or nearly identical component shown in each figure may be represented by the same reference numeral. For clarity, not every component is labeled in each figure. Embodiments of various aspects of the present invention will now be described by way of example and with reference to the accompanying drawings.

[0029] Figure 1 It is a schematic diagram of the hierarchical structure of the environmentally friendly, high temperature resistant and fireproof special cable shown in an embodiment of the present invention.

[0030] Figure 2 It is a schematic diagram of the cross-sectional structure of an environmentally friendly, high-temperature-resistant and fire-resistant special cable shown in an embodiment of the present invention.

[0031] Figure 3 It is a schematic diagram of the enlarged cross-section structure of the conductor core in the environmentally friendly, high-temperature-resistant and fire-proof special cable shown in an embodiment of the present invention.

[0032] Figure 4 It is a schematic diagram of the partial structure of the fire barrier strip in the environmentally friendly, high temperature resistant and fireproof special cable shown in an embodiment of the present invention.

[0033] The definitions of the various symbols in the accompanying drawings are as follows:

[0034] 10. Core conductor; 11. Conducting wire; 12. First insulating layer; 13. Second insulating layer; 131. Protrusion; 14. Fireproof strip; 140. Cavity; 141. Adhesive section; 142. Fireproof filling; 20. Filling cord; 30. Composite wrapping layer; 31. Heat insulation wrapping layer; 32. Thermal radiation isolation layer; 40. Shielding layer; 50. Outer sheath. Detailed implementation mode

[0035] In order to better understand the technical content of the present invention, specific embodiments are hereby given and described in conjunction with the accompanying drawings as follows.

[0036] As Figures 1-4 shown, the present invention provides an environmentally friendly high-temperature resistant and fireproof special cable, aiming to improve the isolation effect of the fireproof swelling material during a fire. The cable includes a cable core, a shielding layer 40, and an outer sheath 50.

[0037] As Figure 2 shown in the example, the cable core includes a core conductor 10 and a filling cord 20 that are twisted together, and the core conductor 10 and the filling cord 20 are wrapped by a composite wrapping layer 30 to form a cable core with a circular cross-section.

[0038] Furthermore, as Figure 1 and Figure 3 shown, the core conductor 10 includes a plurality of conducting wires 11 that are twisted together, and a first insulating layer 12 and a second insulating layer 13 that are coated on the outer side of the conducting wires 11 from the inside to the outside. A through hole is axially formed in the second insulating layer 13, and a fireproof strip 14 is arranged in the through hole. The fireproof strip 14 is filled with a fireproof filling 142, and the fireproof filling 142 can move axially in the fireproof strip 14.

[0039] In some embodiments, the conducting wires 11 are made of annealed oxygen-free fine copper wires and twisted in a regular stranding pattern of 1+6+12+18 to form a conductor. The first insulating layer 12 and the second insulating layer 13 on the outer side are extruded and coated on the outer side of the conductor by a double-layer co-extrusion process. The inner first insulating layer 12 is made of cross-linked polyethylene or silane cross-linked polyethylene, which has good electrical properties, mechanical properties, and heat resistance, and can withstand relatively high working temperatures and voltage levels. The outer second insulating layer 13 is made of flame-retardant polyethylene PVC or silicone rubber, and a through hole is formed during the extrusion process to facilitate the extrusion molding of the inner fireproof strip 14.

[0040] As Figure 3 and Figure 4 shown, the fireproof strip 14 is provided with a plurality of adhesive sections 141 along the length direction. There is a cavity 140 between any two adjacent adhesive sections 141. Both ends of the cavity 140 are sealed by the adhesive sections 141, and each cavity 140 is filled with a fireproof filling 142.

[0041] In some embodiments, during the extrusion process, the fireproof strip 14 is quantitatively filled with the fireproof filling 142, and is pressed at a certain distance to form the bonding section 141, sealing the area filled with the fireproof filling 142. In this way, when some areas are burned through, the fireproof filling 142 in the fireproof strip 14 will flow towards the fire area and gradually accumulate in the fire area to form a relatively thick fireproof barrier. Compared with the existing fixed spraying method, the movable fireproof filling 142 can gather from the non-fire area towards the fire area, forming a thicker barrier in the area where fireproofing is required, thus achieving a better fireproof effect.

[0042] Preferably, the proportion of the fireproof filling 142 in each cavity 140 is between 1 / 2 and 2 / 3. Among them, the fireproof filling 142 can adopt a fireproof expanding filling paste, such as an expandable graphite paste filled with a flame retardant. The space in the cavity 140 other than the fireproof filling 142 is filled with carbon dioxide or air.

[0043] In some embodiments, the fireproof filling 142 can also adopt a liquid or powder fireproof expanding material. The form of the material is related to the added base material. Its fireproof expanding performance mainly depends on the internally added fireproof agent and expanding agent. According to the usage requirements, the form of the fireproof filling 142 is determined. Among them, the paste and liquid fillers have relatively good fluidity and can be extruded and discharged from the defect opening under the expansion of the internal gas pressure. It should be understood that the gas filled in the cavity 140 is not limited to air or carbon dioxide. For example, carbon dioxide not only is not easy to oxidize the internal filling material, but also can expand and extrude the fireproof expanding material in the cavity 140 under high temperature environment, promoting the discharge of the fireproof expanding material. At the same time, it can also reduce the oxygen content in the area, which is beneficial to reducing the fire.

[0044] In this way, in the case of external high temperature, the air or carbon dioxide in the cavity 140 will be compressed and expanded. When the fireproof strip 14 is damaged, the gas pressure will extrude the fireproof filling 142 inside the cavity 140 outward, enabling the fireproof filling 142 to gather from the non-fire area towards the fire area.

[0045] Optionally, the distance between any two adjacent bonding sections 141 is set to 50CM - 100CM. In this way, multiple independent fireproof sections can be formed on the fireproof strip 14, enabling the gas inside the cavity 140 to have sufficient pressure to promote the flow of the fireproof filling 142 after expansion.

[0046] In some embodiments, the positions of the bonding sections 141 on two adjacent fireproof strips 14 can be staggered in the axial direction. In this way, the part of the fireproof strip 14 filled with the fireproof material can cover the entire cable axially, avoiding the situation where the fireproof material cannot accumulate in this part due to the aggregation of the bonding sections 141 locally.

[0047] As shown Figure 3 in FIG. Figure 3 , a protruding portion 131 is provided on the outer sidewall of the second insulating layer 13, and the protruding portions 131 on any two adjacent second insulating layers 13 are all at the stranding center. Taking the stranding of three groups of conductors in the cable core as an example, the angle of the protruding portion 131 is set to 120 degrees. After the three groups of conductors are stranded, the middle parts are in contact with each other, and the strength is higher.

[0048] Furthermore, the number of fireproof strips 14 distributed on one side of the second insulating layer 13 close to the protruding portion 131 is less than the number of fireproof strips 14 distributed on the other side. In the event of a fire, the outer layer area of the insulating layer first comes into contact with the flame. Therefore, the number of fireproof strips 14 is arranged more in the outer layer than in the inner layer.

[0049] It should be understood that in some embodiments, the fireproof strips 14 are not limited to being inside the second insulating layer 13. Its purpose is to gather the internal movable fireproof filling 142 from the non-fire area to the fire area, forming a thicker barrier in the area where fire prevention is required, and achieving a better fire prevention effect.

[0050] Thus, in some embodiments, the fireproof strips 14 can also be provided between the hierarchical structures, or the fireproof strips 14 and the filling rope 20 can be jointly filled in the gaps between the guide cores 10. At the same time, the shape of the fireproof strips 14 is not limited to a thin tubular shape. According to requirements, the fireproof strips 14 can also be set as a fan shape, a rectangle or a hollow ring shape. Among them, the fan shape and the rectangle have a larger coverage range in the circumferential direction compared with the thin tubular shape, while the hollow ring shape is directly coated on the circumference of the cable core, and its coverage range is larger. Thus, when the fireproof strips 14 are burned through by the flame or high temperature, they can still extrude the expandable flame retardant outward at the burned-through part, so that the expandable flame retardant forms a thicker flame retardant barrier layer at the fire starting part.

[0051] Optionally, the filling rope 20 is made of a glass fiber rope or a mineral fiber rope, and the glass fiber rope or the mineral fiber rope has a good flame retardant effect.

[0052] As shown Figure 1 in FIG. Figure 1 , further, the composite wrapping layer 30 includes a heat insulation wrapping layer 31 and a heat radiation isolation layer 32 that are wrapped in sequence from the inside to the outside, and the wrapping directions of the heat insulation wrapping layer 31 and the heat radiation isolation layer 32 are opposite.

[0053] Among them, the heat insulation wrapping layer 31 includes a mica wrapping tape, and the heat radiation isolation layer 32 includes an aluminum foil or an aluminized foil. Thus, the inner mica wrapping tape can play a role in fireproof isolation, while the outer aluminum foil or aluminized foil can reflect heat radiation. When a fire occurs, the temperature of the inner conductor can be reduced.

[0054] Further, the shielding layer 40 is braided and coated on the outer side of the composite wrapping layer 30, and is formed by braiding fine copper wires with a diameter of less than 0.5 mm to form a braided shielding layer, and the braiding density is greater than 90%.

[0055] The outer sheath 50 is extruded and coated on the outer side of the shielding layer 40, and a low-smoke and halogen-free polyolefin sheath material is used, which has good insulation, flame retardancy, corrosion resistance and protection, and can effectively reduce the toxic gases and smoke generated during a fire, and reduce the impact on personnel and the environment.

[0056] Combined with the fireproof cable design of the above embodiments, by arranging the firestop strips 14 in the second insulating layer 13, when some areas are burned through, the firestop filling 142 in the firestop strips 14 will flow towards the fire area and gradually accumulate in the fire area to form a relatively thick firestop barrier. Compared with the existing fixed spraying method, the movable firestop filling 142 can accumulate from the non-fire area to the fire area, form a thicker barrier in the area where firestop is required, and achieve a better firestop effect.

[0057] The second aspect of the present invention provides a preparation method of an environmentally friendly high-temperature resistant fireproof special cable, including the following steps:

[0058] Step 1, prepare the cable core:

[0059] Step 1.1, prepare the conductor core 10: Use annealed oxygen-free fine copper wires of a stranding machine to be stranded in a regular stranding manner of 1 + 6 + 12 + 18 to form a conductor. Sort the conductor and multiple firestop strips 14 according to a preset position, and use an extruder to extrude and coat the first insulating layer 12 and the second insulating layer 13 on the outer sides of the conductor and the firestop strips 14 in a double-layer co-extrusion manner to form the conductor core 10;

[0060] Step 1.2, prepare the filling rope 20: Use a braiding machine to braid glass fiber or mineral fiber into a rope body for later use;

[0061] Step 1.3, lay up into a cable: Strand the prepared conductor cores 10 with each other, fill the filling rope 20 in the gaps on the outer sides of the conductor cores 10, positively wrap mica tape on the outer sides of the conductor cores 10 and the filling rope 20 to form a heat insulation wrapping layer 31, and then reversely wrap aluminum foil or aluminized foil on the outer side of the heat insulation wrapping layer 31 to form a heat radiation isolation layer 32 to form a cable core with a circular cross-section. The heat insulation wrapping layer 31 and the heat radiation isolation layer 32 form a composite wrapping layer 30;

[0062] Step 2, prepare the shielding layer 40: Use a braiding machine to braid a copper mesh on the outer side of the composite wrapping layer 30, and make the braiding density of the copper mesh greater than 85% to form the shielding layer 40 on the outer side of the composite wrapping layer 30;

[0063] Step 3, fabricate the outer sheath 50: Use an extruder to extrude insulating material to wrap around the outside of the shielding layer 40 to form the outer sheath 50;

[0064] In step 1.1, the fireproof strip 14 is prefabricated into a hollow pipe by an extruder. After the pipe is formed, fireproof filler 142 and gas are periodically and quantitatively filled into the pipe. After filling the fireproof filler 142 in each cycle, the pipe is extruded according to a preset length to form an adhesive section 141 on the pipe, and the filled fireproof filler 142 and gas are sealed in the pipe to fabricate the fireproof strip 14.

[0065] Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Those with ordinary knowledge in the technical field to which the present invention pertains can make various modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to that defined by the claims.

Claims

1. An environmentally friendly, high temperature resistant and fireproof special cable, characterized in that: include: A cable core, comprising a conductor core (10) and a filling rope (20) twisted together, wherein the conductor core (10) and the filling rope (20) are wrapped with a composite wrapping layer (30) to form a cable core with a circular cross-section; A shielding layer (40) braided and coated on the outside of the composite wrapping layer (30); An outer sheath (50) covering the outer side of the shielding layer (40); The conductor core (10) comprises a plurality of mutually twisted conductors (11), and a first insulating layer (12) and a second insulating layer (13) which are coated on the outside of the conductors (11) from the inside to the outside, a through hole is provided in the second insulating layer (13) along the axial direction, a fire barrier strip (14) is provided in the through hole, the fire barrier strip (14) is filled with a fire barrier filler (142), and the fire barrier filler (142) can move in the axial direction in the fire barrier strip (14); The fire barrier strip (14) is provided with a plurality of adhesive sections (141) along the length direction, a cavity (140) is provided between any two adjacent adhesive sections (141), both ends of the cavity (140) are sealed by the adhesive sections (141), and each cavity (140) is filled with the fire barrier filling (142).

2. The environmentally friendly, high temperature resistant and fireproof special cable according to claim 1 is characterized in that: The fire-retardant filling (142) accounts for between 1 / 2 and 2 / 3 of each cavity (140).

3. The environmentally friendly, high temperature resistant and fireproof special cable according to claim 1 is characterized in that: The distance between any two adjacent bonding sections (141) is set to be 50CM-100CM.

4. The environmentally friendly, high temperature resistant and fireproof special cable according to claim 1 is characterized in that: The fire-retardant filling (142) comprises a fire-retardant expansion filling paste, and the space of the cavity (140) other than the fire-retardant filling (142) is filled with carbon dioxide or air.

5. The environmentally friendly, high temperature resistant and fireproof special cable according to any one of claims 1 to 4, characterized in that: A protruding protrusion (131) is provided on the outer side wall of the second insulating layer (13), and the protrusions (131) on any two adjacent second insulating layers (13) are located at the twisting center.

6. The environmentally friendly, high temperature resistant and fireproof special cable according to claim 5, characterized in that: The number of the fire-retardant strips (14) distributed on one side of the second insulating layer (13) close to the protruding portion (131) is smaller than the number of the fire-retardant strips (14) distributed on the other side.

7. The environmentally friendly, high temperature resistant and fireproof special cable according to claim 5, characterized in that: The filling rope (20) comprises a glass fiber rope or a mineral fiber rope.

8. The environmentally friendly, high temperature resistant and fireproof special cable according to claim 5, characterized in that: The composite wrapping layer (30) comprises a heat insulation wrapping layer (31) and a heat radiation isolation layer (32) which are wrapped sequentially from the inside to the outside, and the wrapping directions of the heat insulation wrapping layer (31) and the heat radiation isolation layer (32) are opposite.

9. The environmentally friendly, high temperature resistant and fireproof special cable according to claim 8, characterized in that: The heat insulation wrapping layer (31) comprises a mica wrapping tape, and the heat radiation isolation layer (32) comprises aluminum foil or aluminum-plated foil.

10. The method for preparing the environmentally friendly, high temperature resistant and fireproof special cable according to claim 1, characterized in that: The following steps are involved: Step 1: Prepare the cable core: Step 1.1, preparing a conductor core (10): using a twisting machine to twist a plurality of conductors (11) together to form a conductor, arranging the conductor and a plurality of fire barrier strips (14) according to a preset position, and using an extruder to extrude a first insulating layer (12) and a second insulating layer (13) on the outer side of the conductor and the fire barrier strip (14) in a double-layer co-extrusion manner to form a conductor core (10); Step 1.2, preparing a filling rope (20): using a braiding machine to braid glass fibers or mineral fibers into a rope body; Step 1.3, wrapping into a cable: twisting the prepared conductor cores (10) together, filling the gap outside the conductor cores (10) with a filling rope (20), wrapping a heat insulating wrapping layer (31) forwardly on the outside of the conductor cores (10) and the filling rope (20), and then wrapping a heat radiation isolation layer (32) reversely on the outside of the heat insulating wrapping layer (31) to form a cable core with a circular cross-section, wherein the heat insulating wrapping layer (31) and the heat radiation isolation layer (32) form a composite wrapping layer (30); Step 2, preparing a shielding layer (40): using a braiding machine to braid a copper mesh on the outside of the composite wrapping layer (30), and making the braiding density of the copper mesh greater than 85%, so as to form a shielding layer (40) on the outside of the composite wrapping layer (30); Step 3, preparing the outer sheath (50): using an extruder to extrude an insulating material to cover the outer side of the shielding layer (40) to form the outer sheath (50); In step 1.1, the fire-retardant strip (14) is pre-formed into a hollow tube by an extruder. After the tube is formed, a fire-retardant filler (142) and a gas are periodically and quantitatively filled into the tube. After the fire-retardant filler (142) is filled in each cycle, the tube is extruded to a preset length to form a bonding section (141) on the tube, and the filled fire-retardant filler (142) and the gas are sealed in the tube to form the fire-retardant strip (14).

Images