Flame-retardant B1-level fireproof cable

Abstract

The invention relates to the technical field of cables, and particularly discloses a flame-retardant B1-level fireproof cable which is provided with a cable core composed of a plurality of insulated wire cores. A ceramic silicone rubber composite belt layer, a halogen-free low-smoke high-flame-retardant belt layer, a metal longitudinal wrapping layer and a sheath layer are sequentially coated outside the cable core from inside to outside; each insulating wire core is provided with a conductor with a stranded structure, and a mineral wrapping layer and an insulating layer which are coated outside the conductor from inside to outside; gaps of the cable core are filled with high-flame-retardant filling ropes. The flame-retardant B1-level fireproof cable disclosed by the invention not only can meet the technical requirements on the combustion performance level in the corresponding technical standard, but also can be prevented from being broken down after being knocked and vibrated for 15 minutes under the flame of 950-1350 DEG C, and is good in fireproof performance.

Description

Technical Field

[0001] The present invention relates to the technical field of cables, in particular to a flame-retardant B1-grade fireproof cable. Background Art

[0002] As power transmission facilities, the safety of cables directly impacts the safety of life and property in their surroundings. To this end, China promulgated the mandatory national standard GB31247-2014, "Classification of the Flammability of Electrical and Optical Fiber Cables," on December 5, 2014. This technical standard quantifies the flame-retardant performance of cables and categorizes them into four flame-retardant grades: A, B, C, and D. Flame-retardant grade B1 cables are primarily used in densely populated key projects such as subways and high-rise buildings.

[0003] In the prior art, there are many technologies involving Class B1 flame-retardant cables, such as the Chinese patent document entitled "A Class B1 Flame-Retardant Cable," with publication number CN 110570981 A and publication date December 13, 2019; "A Class B1 Cable with Integrated Protection for Rail Transit," with publication number CN 114005590 A and publication date February 1, 2022; and "A New Low-Smoke Halogen-Free Flame-Retardant Class B1 Cable," with publication number CN 111681824 A and publication date September 18, 2020. However, the technical focus of these flame-retardant cables is on how to comply with the corresponding provisions of the above-mentioned technical standards. It is difficult to design beyond these provisions and enhance reliable fire protection performance, making it difficult to effectively adapt to complex, changing, and harsh fire scenes. It is necessary to make more reasonable technical improvements. Summary of the Invention

[0004] The technical purpose of the present invention is to provide a flame-retardant B1 class fireproof cable that can meet the requirements of the corresponding technical standards and reliably enhance the fire resistance performance in view of the particularity of the above-mentioned flame-retardant B1 class cable and the shortcomings of the existing technology.

[0005] The technical purpose of the present invention is achieved by the following technical solution: a flame retardant B1 grade fireproof cable, having a cable core composed of multiple insulated cores; The cable core is coated with a ceramic silicone rubber composite tape layer, a halogen-free low-smoke high flame retardant tape layer, a metal longitudinal cladding layer and a sheath layer in sequence from the inside out; The insulated wire core has a stranded conductor, and a mineral wrapping layer and an insulation layer wrapped around the conductor from the inside out; The gaps in the cable core are filled with highly flame-retardant filling ropes.

[0006] Furthermore, the conductor of the insulated core is formed by twisting a round conductor with a circular cross section and a plurality of shaped wire conductors with a fan-shaped cross section; Among them, a plurality of wire conductors are twisted around the circular conductor in layers according to a concentric circle structure with the circular conductor as the twisting center; The conductor has a twist filling factor of ≥0.97.

[0007] Furthermore, the mineral wrapping layer of the insulating core is composed of at least one layer of overlapping wrapping structure of an inner ceramic silicone rubber composite tape and at least one layer of overlapping wrapping structure of an outer mica tape; The overlapping rate of the overlapping wrapping is ≥30%.

[0008] Furthermore, the insulating layer of the insulated core is an extruded structure of cross-linked polyethylene material outside the mineral wrapping layer.

[0009] Furthermore, the cable core is a twisted structure of multiple insulated wire cores; The highly flame-retardant filling rope is filled in the twisted gaps of a plurality of insulating cores.

[0010] Furthermore, the ceramic silicone rubber composite tape layer is a structure in which at least one layer of ceramic silicone rubber composite tape is wrapped around the outside of the cable core; The overlapping rate of the overlapping wrapping is ≥30%.

[0011] Furthermore, the halogen-free, low-smoke, high-flame-retardant tape layer is a structure in which at least one layer of halogen-free, low-smoke, high-flame-retardant tape is wrapped around the ceramic silicone rubber composite tape layer; The overlapping rate of the overlapping wrapping is ≥30%.

[0012] Furthermore, the metal longitudinal cladding is a longitudinally wrapped structure of a metal belt outside the halogen-free, low-smoke, high-flame-retardant belt layer, and the longitudinal wrapping joints are sealed by argon arc welding. The metal longitudinal cladding is tubular outside the halogen-free, low-smoke, high-flame-retardant belt layer.

[0013] Furthermore, the outer wall of the metal longitudinal cladding has a spiral corrugated structure.

[0014] Furthermore, the sheath layer is an extruded structure of low-smoke halogen-free flame-retardant polyolefin material outside the metal longitudinal cladding; The proportion of the low-smoke halogen-free flame-retardant polyolefin material is calculated according to the following weight parts: EVA 15-20 parts, PE 6-10 parts, 5-10 parts of grafting material, 50-65 parts of flame retardant, 0.5-1 part antioxidant, 1-2 parts of lubricant, 1 part color powder; The flame retardant is a mixture of aluminum hydroxide, magnesium hydroxide and phosphorus nitrogen flame retardant.

[0015] The beneficial technical effect of the present invention is that the flame-retardant B1-class fireproof cable adopting the above-mentioned technical measures, through the comprehensive coordination between the various structural layers, has been tested and demonstrated that its flame spread (FS), peak heat release rate (HRR peak), total heat release within 1200 seconds of exposure (THR1200), peak smoke production rate (SPR peak), and vertical flame spread (H) all meet the combustion performance level technical requirements for flame-retardant B1-class cables in the corresponding technical standards. Furthermore, after combustion, there are no burning drips or particles within 1200 seconds, the smoke toxicity level reaches ZAs, and the cable does not break down after being subjected to percussion and vibration for 15 minutes under a flame of 950-1350°C, demonstrating excellent fireproof performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of the present invention.

[0017] The meaning of the codes in the figure are: 1—conductor; 2—mineral sheath; 3—insulation layer; 4—high flame retardant filling rope; 5—ceramic silicone rubber composite tape layer; 6—halogen-free low-smoke high flame retardant tape layer; 7—metal longitudinal sheath; 8—sheath layer. DETAILED DESCRIPTION

[0018] The present invention relates to the field of cable technology, specifically a flame retardant B1 grade fireproof cable. The following is a detailed description of the main technical solution of the present invention in conjunction with multiple embodiments. Figure 1 The technical solution of the present invention is clearly and in detail explained; although other embodiments are not separately drawn with drawings, their main structures can still refer to the drawings of Example 1.

[0019] It should be noted that the drawings of the present invention are schematic and have been simplified to clarify the technical objectives of the present invention and to avoid obscuring the present invention's contribution to the prior art. Furthermore, expressions such as "approximately" and "substantially" regarding quantities or fitting relationships below are intended to allow for reasonable assembly and processing errors within the industry and do not literally represent absolute quantities or fitting relationships.

[0020] Example 1 See also Figure 1As shown, the present invention is a flame-retardant Class B1 fireproof cable with a core composed of four twisted insulated wire cores. The interstices between the twisted cores are filled with multiple highly flame-retardant filler cords 4. These highly flame-retardant filler cords 4 fill the interstices between the four insulated wire cores and round the core, resulting in a regular, compact, and stable outer structure. The highly flame-retardant filler cords 4 also enhance the flame retardancy of the cable core.

[0021] Each insulated core constituting the cable core comprises a stranded conductor 1, and a mineral wrapping layer 2 and an insulating layer 3 covering the conductor 1 from the inside out.

[0022] The insulated core conductor 1 is a copper round conductor with a circular cross-section and several copper profile conductors with fan-shaped cross-sections, twisted together. The round conductor is drawn according to the diameter unit, and the profile conductor is produced and formed according to the cross-section unit. The specific twisting structure is that several profile conductors are twisted in layers on the periphery of the round conductor in a concentric circle structure with the round conductor as the twisting center. The basic twisting structure is a specification of 1+6+12+18. The twisted conductor 1 has a twisting filling coefficient of approximately 0.97. The aforementioned conductor 1 can effectively enhance waterproof performance while carrying high current.

[0023] The mineral wrapping layer 2 of the insulated core is composed of a layer of overlapping ceramic silicone rubber composite tape on the inside and a layer of overlapping mica tape on the outside, with an overlap ratio of approximately 30%. The formation of the mineral wrapping layer 2 not only provides the structural properties of the conductor's insulation shield, but also improves the conductor's moisture resistance and flame retardancy.

[0024] The insulating layer 3 of the insulated wire core is an extruded structure of cross-linked polyethylene material outside the mineral wrapping layer 2. The insulating layer 3 is easy to shape and has excellent insulation performance.

[0025] The outside of the cable core structure is covered in sequence from the inside out with a ceramic silicone rubber composite tape layer 5, a halogen-free low-smoke high flame retardant tape layer 6, a metal longitudinal sheath 7 and a sheath layer 8.

[0026] The ceramic silicone rubber composite tape layer 5 is a double-layered, overlapping structure of ceramic silicone rubber composite tape wrapped around the cable core, with each layer having an overlap ratio of approximately 30%. The ceramic silicone rubber composite tape layer 5 has insulating, moisture-resistant, and flame-retardant properties.

[0027] The halogen-free, low-smoke, highly flame-retardant tape layer 6 consists of two overlapping layers of halogen-free, low-smoke, highly flame-retardant tape wrapped around the ceramic silicone rubber composite tape layer 5, with each layer overlapping at approximately 30%. This halogen-free, low-smoke, highly flame-retardant tape layer 6 effectively meets the combustion performance and environmental protection requirements of Class B1 flame-retardant cables.

[0028] The metal longitudinal cladding 7, a copper strip approximately 0.08mm thick, is longitudinally wrapped around the outer surface of the halogen-free, low-smoke, highly flame-retardant tape layer 6. The longitudinal cladding seams are sealed using argon arc welding. The metal longitudinal cladding 7 is tubular and extends outside the halogen-free, low-smoke, highly flame-retardant tape layer 6, providing isolation, pressure resistance, and fire protection, thereby enhancing these properties. To ensure stable adhesion of the outer sheath layer 8 to the metal longitudinal cladding 7, the outer wall of the metal longitudinal cladding 7 is provided with a spiral corrugation structure.

[0029] The sheath layer 8 is an extruded structure of low-smoke, halogen-free, flame-retardant polyolefin material over the metal longitudinal cladding layer 7. The low-smoke, halogen-free, flame-retardant polyolefin material is formulated in the following proportions by weight: 18 parts EVA, 8 parts PE, 7 parts grafting material, 60 parts flame retardant, 0.8 parts antioxidant, 1.5 parts lubricant, and 1 part colorant. The flame retardant is a 1:1:1 mixture of aluminum hydroxide, magnesium hydroxide, and a phosphorus-nitrogen flame retardant. The low-smoke, halogen-free, flame-retardant polyolefin material is melt-blended in a banbury mixer at approximately 175°C, followed by twin-screw and single-screw pelletization. The sheath layer 8, formed from the low-smoke, halogen-free, flame-retardant polyolefin material, not only exhibits excellent environmental resistance but also forms a crust during combustion, providing flame retardancy and fire protection.

[0030] Example 2 This flame-retardant, Class B1 fireproof cable features a core composed of four twisted insulated wire cores. The interstices between the twisted cores are filled with multiple highly flame-retardant filler cords. These filler cords fill the interstices between the four insulated wire cores and round the core, resulting in a regular, compact, and stable outer structure. The highly flame-retardant filler cords also enhance the flame-retardant properties of the cable core.

[0031] Each insulated core that makes up the cable core has a stranded conductor, a mineral sheath and an insulation layer that wraps around the conductor from the inside out.

[0032] The insulated core conductor is a copper round conductor with a circular cross-section and several copper profiled wire conductors with a fan-shaped cross-section, twisted together. The round conductor is drawn according to the diameter unit, and the profiled wire conductor is produced and formed according to the cross-section unit. The specific twisting structure is that several profiled wire conductors are twisted in layers around the outer periphery of the round conductor in a concentric circle structure with the round conductor as the twisting center. The basic twisting structure is a specification of 1+6+12; the conductor twisted in this way has a twisting fill factor of approximately 0.98. The aforementioned conductors can effectively enhance waterproof performance while carrying high current.

[0033] The mineral wrapping layer of the insulated core is composed of a layer of overlapping ceramic silicone rubber composite tape on the inside and a layer of overlapping mica tape on the outside, with an overlap ratio of approximately 35%. The formation of the mineral wrapping layer not only forms the structural properties of the conductor's insulation shield, but also improves the conductor's moisture resistance and flame retardancy.

[0034] The insulation layer of the insulated wire core is an extruded structure of cross-linked polyethylene material outside the mineral wrapping layer. This insulation layer is easy to form and has excellent insulation performance.

[0035] The outside of the cable core structure is covered in sequence from the inside out with a ceramic silicone rubber composite tape layer, a halogen-free low-smoke high flame retardant tape layer, a metal longitudinal sheath layer and a sheath layer.

[0036] The ceramic silicone rubber composite tape layer is a layer of ceramic silicone rubber composite tape wrapped around the cable core, with an overlap ratio of approximately 40%. The ceramic silicone rubber composite tape layer has insulating, moisture-resistant, and flame-retardant properties.

[0037] The halogen-free, low-smoke, highly flame-retardant tape layer is an overlapping layer of halogen-free, low-smoke, highly flame-retardant tape wrapped around the ceramic silicone rubber composite tape layer, with an overlap ratio of approximately 40%. This halogen-free, low-smoke, highly flame-retardant tape layer effectively meets the combustion performance and environmental protection technical requirements of flame-retardant B1-class cables.

[0038] The metal longitudinal cladding is a copper strip approximately 0.05mm thick, wrapping the outer surface of the halogen-free, low-smoke, highly flame-retardant tape layer. The longitudinal cladding seams are sealed using argon arc welding. The metal longitudinal cladding is tubular and forms a barrier to the outer surface of the halogen-free, low-smoke, highly flame-retardant tape layer, providing isolation, pressure resistance, and fire resistance, thereby enhancing these properties. To ensure stable adhesion of the outer sheath layer to the metal longitudinal cladding, a spiral corrugation structure is applied to the outer wall of the metal longitudinal cladding.

[0039] The sheath layer is an extruded structure of low-smoke, halogen-free, flame-retardant polyolefin material over the metal longitudinal cladding. The low-smoke, halogen-free, flame-retardant polyolefin material is formulated in the following proportions by weight: 20 parts EVA, 10 parts PE, 10 parts grafting material, 65 parts flame retardant, 1 part antioxidant, 2 parts lubricant, and 1 part colorant. The flame retardant is a mixture of aluminum hydroxide, magnesium hydroxide, and phosphorus nitrogen flame retardant in a ratio of 1:1:0.8. The low-smoke, halogen-free, flame-retardant polyolefin material is melt-blended in a banbury mixer at approximately 180°, followed by twin-screw and single-screw pelletization. The sheath layer, molded from this low-smoke, halogen-free, flame-retardant polyolefin material, not only exhibits excellent environmental resistance but also forms a crust during combustion, providing flame retardancy and fire protection.

[0040] Example 3 This flame-retardant, Class B1 fireproof cable features a core consisting of five twisted insulated wire cores. The interstices between the twisted cores are filled with multiple highly flame-retardant filler cords. These filler cords fill the interstices between the four insulated wire cores and round the core, resulting in a regular, compact, and stable outer structure. The highly flame-retardant filler cords also enhance the flame-retardant properties of the cable core.

[0041] Each insulated core that makes up the cable core has a stranded conductor, a mineral sheath and an insulation layer that wraps around the conductor from the inside out.

[0042] The insulated core conductor is a copper round conductor with a circular cross-section and several copper profiled wire conductors with a fan-shaped cross-section, twisted together. The round conductor is drawn according to the diameter unit, and the profiled wire conductor is produced and formed according to the cross-section unit. The specific twisting structure is that several profiled wire conductors are twisted in layers around the outer periphery of the round conductor in a concentric circle structure with the round conductor as the twisting center. The basic twisting structure is a specification of 1+6+12; the conductor twisted in this way has a twisting fill factor of approximately 0.98. The aforementioned conductors can effectively enhance waterproof performance while carrying high current.

[0043] The mineral wrapping layer of the insulated core is composed of an inner layer of overlapping ceramic silicone rubber composite tape and an outer layer of overlapping mica tape, with an overlap ratio of approximately 50%. The formation of the mineral wrapping layer not only forms the structural properties of the conductor's insulation shield, but also improves the conductor's moisture resistance and flame retardancy.

[0044] The insulation layer of the insulated wire core is an extruded structure of cross-linked polyethylene material outside the mineral wrapping layer. This insulation layer is easy to form and has excellent insulation performance.

[0045] The outside of the cable core structure is covered in sequence from the inside out with a ceramic silicone rubber composite tape layer, a halogen-free low-smoke high flame retardant tape layer, a metal longitudinal sheath layer and a sheath layer.

[0046] The ceramic silicone rubber composite tape layer is a double-layered, overlapping structure of ceramic silicone rubber composite tape wrapped around the cable core, with each layer overlapping at a coverage rate of approximately 50%. The ceramic silicone rubber composite tape layer has insulating, moisture-resistant, and flame-retardant properties.

[0047] The halogen-free, low-smoke, highly flame-retardant tape layer consists of two overlapping layers of halogen-free, low-smoke, highly flame-retardant tape wrapped around the ceramic silicone rubber composite tape layer, with each layer overlapping at approximately 50%. This halogen-free, low-smoke, highly flame-retardant tape layer effectively meets the combustion performance and environmental protection requirements of Class B1 flame-retardant cables.

[0048] The metal longitudinal cladding is an aluminum tape approximately 1mm thick, wrapping the outer surface of the halogen-free, low-smoke, highly flame-retardant tape layer. The longitudinal cladding seams are sealed using argon arc welding. The metal longitudinal cladding is tubular and forms a barrier to the outer surface of the halogen-free, low-smoke, highly flame-retardant tape layer, providing isolation, pressure resistance, and fire resistance, thereby enhancing these properties. To ensure stable adhesion of the outer sheath layer to the metal longitudinal cladding, a spiral corrugation structure is applied to the outer wall of the metal longitudinal cladding.

[0049] The sheath layer is an extruded structure of polyolefin material outside the metal longitudinal sheath.

[0050] Example 4 This flame-retardant, Class B1 fireproof cable features a core consisting of three twisted insulated wire cores. The interstices between the twisted cores are filled with multiple highly flame-retardant filler cords. These filler cords fill the interstices between the four insulated wire cores and round the core, resulting in a regular, compact, and stable outer structure. The highly flame-retardant filler cords also enhance the flame-retardant properties of the cable core.

[0051] Each insulated core that makes up the cable core has a stranded conductor, a mineral sheath and an insulation layer that wraps around the conductor from the inside out.

[0052] The insulated core conductor is a copper round conductor with a circular cross-section and several copper profile conductors with a fan-shaped cross-section, twisted together. The round conductor is drawn according to the diameter unit, and the profile conductor is produced according to the cross-section unit. The specific twisting structure is that several profile conductors are twisted in layers around the outer periphery of the round conductor in a concentric circle structure with the round conductor as the twisting center. The basic twisting structure is a specification of 1+6+12+18+24; the conductor twisted in this way has a twisting fill factor of approximately 0.97. The aforementioned conductor can effectively enhance waterproof performance while carrying high current.

[0053] The mineral wrapping layer of the insulated core is composed of a double-layered structure of ceramic silicone rubber composite tape on the inside and mica tape on the outside, with an overlap ratio of approximately 45%. The formation of the mineral wrapping layer not only forms the structural properties of the conductor's insulation shield, but also improves the conductor's moisture resistance and flame retardancy.

[0054] The insulation layer of the insulated wire core is an extruded structure of cross-linked polyethylene material outside the mineral wrapping layer. This insulation layer is easy to form and has excellent insulation performance.

[0055] The outside of the cable core structure is covered in sequence from the inside out with a ceramic silicone rubber composite tape layer, a halogen-free low-smoke high flame retardant tape layer, a metal longitudinal sheath layer and a sheath layer.

[0056] The ceramic silicone rubber composite tape layer is a three-layer overlapping structure of ceramic silicone rubber composite tape wrapped around the cable core, with each layer overlapping at a coverage rate of approximately 30%. The ceramic silicone rubber composite tape layer has insulating, moisture-resistant, and flame-retardant properties.

[0057] The halogen-free, low-smoke, highly flame-retardant tape layer consists of three overlapping layers of halogen-free, low-smoke, highly flame-retardant tape wrapped around the ceramic silicone rubber composite tape layer, with each layer overlapping at approximately 30%. This halogen-free, low-smoke, highly flame-retardant tape layer effectively meets the combustion performance and environmental protection requirements of Class B1 flame-retardant cables.

[0058] The metal longitudinal cladding is a copper strip approximately 0.08mm thick, wrapping the outer surface of the halogen-free, low-smoke, highly flame-retardant tape layer. The longitudinal cladding seams are sealed using argon arc welding. The metal longitudinal cladding is tubular and forms a barrier to the outer surface of the halogen-free, low-smoke, highly flame-retardant tape layer, providing isolation, pressure resistance, and fire resistance, thereby enhancing these properties. To ensure stable adhesion of the outer sheath layer to the metal longitudinal cladding, a spiral corrugation structure is applied to the outer wall of the metal longitudinal cladding.

[0059] The sheath layer is an extruded structure of low-smoke halogen-free material outside the metal longitudinal cladding.

[0060] Example 5 This flame-retardant, Class B1 fireproof cable features a core composed of four twisted insulated wire cores. The interstices between the twisted cores are filled with multiple highly flame-retardant filler cords. These filler cords fill the interstices between the four insulated wire cores and round the core, resulting in a regular, compact, and stable outer structure. The highly flame-retardant filler cords also enhance the flame-retardant properties of the cable core.

[0061] Each insulated core that makes up the cable core has a stranded conductor, a mineral sheath and an insulation layer that wraps around the conductor from the inside out.

[0062] The insulated core conductor is a copper round conductor with a circular cross-section and several copper profiled wire conductors with a fan-shaped cross-section, twisted together. The round conductor is drawn according to the diameter unit, and the profiled wire conductor is produced and formed according to the cross-section unit. The specific twisting structure is that several profiled wire conductors are twisted in layers around the outer periphery of the round conductor in a concentric circle structure with the round conductor as the twisting center. The basic twisting structure is a specification of 1+6+12; the conductor twisted in this way has a twisting fill factor of approximately 0.98. The aforementioned conductors can effectively enhance waterproof performance while carrying high current.

[0063] The mineral wrapping layer of the insulated core is composed of a layer of overlapping ceramic silicone rubber composite tape on the inside and a layer of overlapping mica tape on the outside, with an overlap ratio of approximately 40%. The formation of the mineral wrapping layer not only forms the structural properties of the conductor's insulation shield, but also improves the conductor's moisture resistance and flame retardancy.

[0064] The insulation layer of the insulated wire core is an extruded structure of cross-linked polyethylene material outside the mineral wrapping layer. This insulation layer is easy to form and has excellent insulation performance.

[0065] The outside of the cable core structure is covered in sequence from the inside out with a ceramic silicone rubber composite tape layer, a halogen-free low-smoke high flame retardant tape layer, a metal longitudinal sheath layer and a sheath layer.

[0066] The ceramic silicone rubber composite tape layer is a double-layered, overlapping structure wrapped around the cable core, with each layer overlapping at a coverage rate of approximately 35%. The ceramic silicone rubber composite tape layer has insulating, moisture-resistant, and flame-retardant properties.

[0067] The halogen-free, low-smoke, highly flame-retardant tape layer consists of a double layer of overlapping halogen-free, low-smoke, highly flame-retardant tape wrapped around the ceramic silicone rubber composite tape layer, with each layer overlapping at approximately 35%. This halogen-free, low-smoke, highly flame-retardant tape layer effectively meets the combustion performance and environmental protection requirements of Class B1 flame-retardant cables.

[0068] The metal longitudinal cladding is a copper strip approximately 0.08mm thick, wrapping the outer surface of the halogen-free, low-smoke, highly flame-retardant tape layer. The longitudinal cladding seams are sealed using argon arc welding. The metal longitudinal cladding is tubular and forms a barrier to the outer surface of the halogen-free, low-smoke, highly flame-retardant tape layer, providing isolation, pressure resistance, and fire resistance, thereby enhancing these properties. To ensure stable adhesion of the outer sheath layer to the metal longitudinal cladding, a spiral corrugation structure is applied to the outer wall of the metal longitudinal cladding.

[0069] The sheath layer is an extruded structure of low-smoke, halogen-free, flame-retardant polyolefin material over the metal longitudinal cladding. The low-smoke, halogen-free, flame-retardant polyolefin material is formulated in the following proportions by weight: 15 parts EVA, 6 parts PE, 5 parts grafting material, 50 parts flame retardant, 0.5 parts antioxidant, 1 part lubricant, and 1 part colorant. The flame retardant is a mixture of aluminum hydroxide, magnesium hydroxide, and phosphorus-nitrogen flame retardant in a ratio of 1:0.7:0.5. The low-smoke, halogen-free, flame-retardant polyolefin material is melt-blended in a banbury mixer at approximately 175°, followed by twin-screw and single-screw pelletization. The sheath layer, molded from this low-smoke, halogen-free, flame-retardant polyolefin material, not only exhibits excellent environmental resistance but also forms a crust during combustion, providing flame retardancy and fire protection.

[0070] The above embodiments are only used to illustrate the present invention, rather than to limit it.

[0071] Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the above embodiments or make equivalent replacements for some of the technical features therein; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the present invention.

Claims

1. A flame retardant B1 fireproof cable with a cable core consisting of multiple insulated cores; Its characteristics are: The cable core is coated with a ceramic silicone rubber composite tape layer (5), a halogen-free low-smoke high-flame retardant tape layer (6), a metal longitudinal cladding layer (7) and a sheath layer (8) in sequence from the inside out; The insulated wire core comprises a stranded conductor (1), and a mineral wrapping layer (2) and an insulating layer (3) wrapped around the conductor (1) from the inside out; The gaps in the cable core are filled with highly flame-retardant filling ropes (4).

2. The flame-retardant B1-class fireproof cable according to claim 1, characterized in that: The conductor (1) of the insulated wire core is formed by twisting a round conductor with a circular cross-section and a plurality of shaped wire conductors with a fan-shaped cross-section; Among them, a plurality of wire conductors are twisted around the circular conductor in layers according to a concentric circle structure with the circular conductor as the twisting center; The conductor (1) has a twist filling factor of ≥0.

97.

3. The flame-retardant B1-class fireproof cable according to claim 1, characterized in that: The mineral wrapping layer (2) of the insulating core is composed of at least one layer of overlapping wrapping structure of an inner ceramic silicone rubber composite tape and at least one layer of overlapping wrapping structure of an outer mica tape; The overlapping rate of the overlapping wrapping is ≥30%.

4. The flame-retardant B1 fireproof cable according to claim 1, characterized in that: The insulating layer (3) of the insulating core is an extruded structure of a cross-linked polyethylene material outside the mineral wrapping layer (2).

5. The flame-retardant B1 fireproof cable according to claim 1, characterized in that: The cable core is a twisted structure of multiple insulated wire cores; The highly flame-retardant filling rope (4) is filled in the twisted gaps between the plurality of insulated wire cores.

6. The flame-retardant B1 fireproof cable according to claim 1, characterized in that: The ceramic silicone rubber composite tape layer (5) is a structure in which at least one layer of ceramic silicone rubber composite tape is wrapped around the outside of the cable core; The overlapping rate of the overlapping wrapping is ≥30%.

7. The flame-retardant B1 fireproof cable according to claim 1, characterized in that: The halogen-free, low-smoke, high-flame-retardant tape layer (6) is a structure in which at least one layer of halogen-free, low-smoke, high-flame-retardant tape is wrapped around the outside of the ceramic silicone rubber composite tape layer (5); The overlapping rate of the overlapping wrapping is ≥30%.

8. The flame-retardant B1-class fireproof cable according to claim 1, characterized in that: The metal longitudinal cladding (7) is a longitudinally wrapped structure of a metal strip outside the halogen-free, low-smoke, high-flame-retardant tape layer (6), and the longitudinal cladding joint is sealed by argon arc welding. The metal longitudinal cladding (7) is tubular outside the halogen-free, low-smoke, high-flame-retardant tape layer (6).

9. The flame-retardant B1 fireproof cable according to claim 1 or 8, characterized in that: The outer wall of the metal longitudinal cladding (7) has a spiral corrugated structure.

10. The flame-retardant B1-class fireproof cable according to claim 1, characterized in that: The sheath layer (8) is an extruded structure of a low-smoke, halogen-free, flame-retardant polyolefin material outside the metal longitudinal cladding layer (7); The proportion of the low-smoke halogen-free flame-retardant polyolefin material is calculated according to the following weight parts: EVA 15-20 parts, PE 6-10 parts, 5-10 parts of grafting material, 50-65 parts of flame retardant, 0.5-1 part antioxidant, 1-2 parts of lubricant, 1 part color powder; The flame retardant is a mixture of aluminum hydroxide, magnesium hydroxide and phosphorus nitrogen flame retardant.

Images