A preparation method for a special cable for an aluminum-plastic composite film production line and the cable

Abstract

The present invention discloses a preparation method for a special cable used in an aluminum-plastic composite film production line, which is prepared according to the following method: 1) Mix calcined coal gangue powder and calcined mica powder in a stirrer to fully and evenly mix the two raw materials. Put the mixed powder material into a calcination furnace for calcination, and cool it naturally. Grind the calcined material dry until the particle size of the material is ≤50 μm, and place it in a heat preservation furnace for heat preservation. 2) Fill, tamp, reduce the diameter, anneal and wind up to obtain the cable. The present invention combines magnesium oxide powder with calcined coal series kaolin and calcined mica powder, reduces the water absorption performance of the material through ternary composite complementarity, and at the same time improves the density of the insulating material by precisely controlling the ratio of the composite powder. There is no need to pre-burn porcelain columns, avoiding the problem of low density caused by gas residues, reducing production costs while improving the electrical, insulating and fire-resistant properties of the mineral insulated cable.

Description

Technical Field

[0001] The present invention relates to the technical field of cables, and particularly to a preparation method and a cable of a special cable for an aluminum-plastic composite film production line. Background Art

[0002] Mineral insulated fire-resistant and flame-retardant special cable is a cable with a copper sheath wrapping a copper conductor core wire and an inorganic insulating material isolating the conductor from the sheath. The outermost layer usually selects a copper sheath. Since all materials of this cable are inorganic materials, the mineral insulated fire-resistant and flame-retardant special cable itself does not burn, nor support combustion or assist combustion. Since the melting point of copper is 1083°C and the melting point of the inorganic insulating material is usually as high as over 2800°C, the mineral insulated fire-resistant and flame-retardant special cable can continuously maintain power supply in a fire situation close to the melting point of copper. Even when burned out at a high temperature of 1000°C, it will not release smoke, halogens and toxic gases, and it is a truly halogen-free and non-toxic fire-proof cable. In the process of producing composite aluminum-plastic film, due to the high temperature of the electric furnace, the heat resistance of the conventional cable laid is poor, and it is extremely easy to age in a high-temperature heat environment, resulting in a decrease in insulation performance, a short service life, and easy to cause safety accidents. While the mineral insulated fire-resistant and flame-retardant special cable can effectively overcome these disadvantages.

[0003] Mineral insulated fire-resistant and flame-retardant special cable usually uses magnesium oxide powder as the insulating material. However, magnesium oxide powder is extremely easy to absorb water, resulting in a decrease in insulation performance. In the filling process, it is difficult to control the uniformity and density, which seriously affects the anti-bending and extrusion impact performance of the cable. At present, almost all mineral insulated fire-resistant and flame-retardant special cables prepared with multi-component composite inorganic materials as the insulating material need to send the composite insulating material to a press to be pressed into a porcelain column shape; the pressed porcelain column is put into a storage box or conveyed to an electric furnace by a conveyor belt for calcination; the calcined porcelain column is sent to an assembly table, and hot assembly is used during assembly to ensure no moisture absorption; after assembly, repeated drawing and annealing processes are carried out until the finished product. Due to the inevitable generation of a large number of pores during the calcination process of the porcelain column, the density of the insulating material in the finished product is very low, and the best insulating performance of the composite material cannot be maximally reflected.

[0004] The argon arc welding continuous welding magnesium oxide powder filling method is the most advanced production process of mineral insulated fire-resistant and flame-retardant special cable at present. However, using magnesium oxide particles as the insulating filling material, on the one hand, magnesium oxide is extremely easy to absorb moisture and get damp, reducing the insulating and fire-proof performance of the material. On the other hand, to ensure the density of the magnesium oxide insulating layer during the filling process, large-grained magnesium oxide is usually used for filling, resulting in a larger gap between magnesium oxides, affecting the density of the magnesium oxide insulating layer, and thus reducing the performance of the mineral insulated fire-resistant and flame-retardant special cable. Summary of the Invention

[0005] The object of the present invention is to provide a preparation method and a cable for a special cable used in an aluminum-plastic composite film production line in view of the above-mentioned existing technical problems. Magnesium oxide powder is compounded with calcined coal-series kaolin and calcined mica powder. The water absorption performance of the material is reduced through ternary composite complementarity. At the same time, the density of the insulating material is improved by precisely controlling the ratio of the composite powder. There is no need to pre-burn porcelain columns, avoiding the problem of low density caused by gas residues. While reducing production costs, the electrical, insulating, and fire-resistant properties of the mineral insulated cable are improved. When laid under the furnace, it can improve safety performance, extend service life, and reduce the maintenance frequency.

[0006] In view of this, the present invention provides a preparation method for a special cable used in an aluminum-plastic composite film production line, which is characterized in that it is prepared according to the following method:

[0007] 1) Mix calcined coal gangue powder and calcined mica powder in a stirrer to make the two raw materials fully mixed and uniform. Put the mixed powder material into a calcining furnace and calcine it at 900 °C for 60 - 90 min; after calcination, cool it naturally to 40 - 50 °C and take it out of the furnace. Dry-grind the calcined material until the particle size of the material ≤ 50 μm, and place it in a heat preservation furnace for heat preservation to prevent the calcined composite powder from absorbing water and getting damp.

[0008] (2) Clean and decontaminate the copper tube and the core material. Put the required core material into the copper tube on the assembly table for blank assembly, and fix one end of the copper tube.

[0009] (3) Take out the calcined composite powder from the heat preservation box, add heavy magnesium oxide. Among them, the mass ratio of the calcined composite powder to the heavy magnesium oxide is 4 - 5:5 - 6; after mixing evenly, remove the magnetic metal inclusions in the calcined composite powder, and after moisture removal treatment, pour it into the gap around the copper core in the copper tube.

[0010] (4) The insulated cable filled with the calcined composite powder is further tamped by a vibrating hammer to compact the insulating layer, and undergoes multiple vertical rolling and diameter reduction. It is annealed once at 420 °C - 600 °C, and further horizontally reduced in diameter to meet the design specification size and then annealed twice at 420 °C - 600 °C. Use protective gas to protect the outer surface of the copper tube copper sheath to be bright, and the finished product is wound up for performance testing to obtain a mineral insulated flame-retardant and fire-resistant special cable.

[0011] In the above scheme: by weight, among them, 50 - 60 parts of calcined coal gangue powder and 40 - 50 parts of calcined mica powder.

[0012] In the above solution: In step (1), the heating program of the calciner is as follows: from room temperature to 400°C, for 30 minutes, and hold for 20 minutes; from 400°C to 700°C, for 30 minutes, and hold for 30 minutes; from 700°C to 800°C, for 5 minutes, and hold for 60 minutes; from 800°C to 900°C, for 5 minutes, and hold for 60 - 90 minutes.

[0013] In the above solution: In step (1), the temperature of the holding furnace is 110 - 120°C.

[0014] In the above solution: In step (3), moisture removal treatment is carried out at 180 - 200°C.

[0015] In the above solution: The particle size of heavy magnesium oxide is ≥45μm (325 mesh) and exceeds 90%.

[0016] A cable prepared by a preparation method of a special cable for an aluminum-plastic composite film production line.

[0017] The calcined coal gangue of the present invention contains a large amount of mullite crystals, has good strength, insulation and fire resistance. Different from other kaolins, the calcined coal gangue powder does not absorb water, and well solves the problems of insufficient insulation, poor strength and water absorption after subsequent mixing with heavy magnesium oxide. The present invention patent is calcined at 900°C, which not only destroys the organic matter remaining in the coal gangue powder, but also can remove a large amount of carbon remaining in the coal gangue powder, and the density of the calcined coal gangue is greatly increased. The calcined mica powder removes a small amount of structural water at a high temperature of 400 - 700°C, but does not change the positions of each atom in the structure; at a high temperature of 700 - 800°C, about 50% of the structural water is removed; at a high temperature of 800 - 900°C, not only the structural water is completely removed, but also a large amount of hydroxyl groups in the mica structure are removed, especially the hydroxyl functional groups formed on the crystal surface due to the structural change of the mica crystal, reducing the hydrophilicity of the calcined mica powder. At this temperature, although the atomic positions of mica are greatly adjusted, the mineral characteristics of good insulation and fire resistance of mica are still maintained, and at the same time, the water absorption of mica is reduced. At the same time, the silicon existing in the mica powder will promote the formation of mullite crystals in the calcined coal gangue during the high-temperature calcination process.

[0018] The particle size of the heavy magnesium oxide used in the present invention is ≥45μm (325 mesh) and exceeds 90%. Selecting large-particle magnesium oxide is beneficial to improving the density of the insulating layer, but at the same time, it will also cause the gaps between large-particle magnesium oxides to become larger and more, thus affecting the insulation of the material. After adding a mixed material of calcined coal-series kaolin and calcined mica powder with a particle size ≤50μm, the gaps between heavy magnesium oxides can be effectively filled, thereby greatly improving the density of the material, and overall showing a great improvement in the insulation performance of the cable insulating layer. The mass ratio of the added calcined composite mixed material to heavy magnesium oxide in the present invention patent is 4 - 5:5 - 6.

[0019] The volume resistivity of the insulating cable of the present invention reaches 10 17 Ω·cm level. Compared with the previous CN202011461772.7, the insulation performance of the product insulator has been improved by nearly one order of magnitude, and the high-temperature resistance of the insulator still remains above 2800 °C, which is 300 - 500 °C higher than that of domestic similar products and reaches the standard of international advanced level. The minimum continuous power supply time during a fire reaches 300 - 360 min, which is 240 - 300 min longer than that of domestic similar products and far greater than the international standard of 60 min. The bending resistance and extrusion impact resistance of the mineral insulated special cable of the present invention have been greatly improved, and the minimum bending radius is significantly better than that of previous similar products.

[0020] The present invention uses cheap calcined coal gangue and calcined mica powder to compound and replace nearly half of the heavy magnesium oxide. While obtaining a high-performance mineral insulated special cable, the cost of the insulating material is reduced by more than half. Specific embodiments

[0021] The present invention will be further described below in conjunction with embodiments.

[0022] Embodiment 1

[0023] A method for preparing a special cable for an aluminum-plastic composite film production line is prepared according to the following method:

[0024] 1) Mix calcined coal gangue powder and calcined mica powder in a stirrer to make the two raw materials fully mixed evenly, with 60 parts of calcined coal gangue powder and 40 parts of calcined mica powder. Put the mixed powder material into a calcining furnace and calcine it at 900 °C. The heating program of the calcining furnace is: heat up from room temperature to 400 °C for 30 min and keep it for 20 min; heat up from 400 °C to 700 °C for 30 min and keep it for 30 min; heat up from 700 °C to 800 °C for 5 min and keep it for 60 min; heat up from 800 °C to 900 °C for 5 min and keep it for 90 min.

[0025] After calcination, cool it naturally to 40 - 50 °C and take it out of the furnace. Grind the calcined material dry until the particle size of the material ≤ 50 μm, and place it in a heat preservation furnace at 110 - 120 °C for heat preservation to prevent the calcined composite powder from absorbing water and getting damp.

[0026] (2) Clean and decontaminate the copper tube and the core material. Put the required core material into the copper tube on the assembly table for blank assembly, and fix one end of the copper tube.

[0027] (3) Take out the calcined composite powder from the incubator, add heavy magnesium oxide, with the particle size of heavy magnesium oxide ≥ 45μm (325 mesh) exceeding 90%. Among them, the mass ratio of the calcined composite powder to heavy magnesium oxide is 5:5; After mixing evenly, remove the magnetic metal inclusions in the calcined composite powder, and after moisture discharge treatment at 180 - 200°C, pour it into the gap around the copper core in the copper tube.

[0028] (4) Vibration hammer micro-vibration is carried out on the insulated cable filled with the calcined composite powder to further compact the insulating layer, and multi-channel vertical rolling and diameter reduction are carried out, followed by primary annealing at 420°C - 600°C. After further horizontal diameter reduction to meet the design specification dimensions, secondary annealing is carried out at 420°C - 600°C. Use protective gas (inert gas such as nitrogen) to protect the outer surface of the copper tube copper sheath to be bright, and the finished product is wound up for performance testing to obtain a mineral insulated flame-retardant and fire-resistant special cable.

[0029] Example 2

[0030] A preparation method of a special cable for an aluminum-plastic composite film production line is prepared according to the following method:

[0031] 1) Mix the calcined coal gangue powder and the calcined mica powder in a stirrer to make the two raw materials fully mixed evenly, with 50 parts of calcined coal gangue powder and 50 parts of calcined mica powder. Put the mixed powder material into a calcining furnace and calcine it at 900°C. The heating program of the calcining furnace is as follows: heat up from room temperature to 400°C for 30 min and hold for 20 min; heat up from 400°C to 700°C for 30 min and hold for 30 min; heat up from 700°C to 800°C for 5 min and hold for 60 min; heat up from 800°C to 900°C for 5 min and hold for 60 min.

[0032] After calcination, naturally cool it to 40 - 50°C and take it out of the furnace, dry-grind the calcined material until the particle size ≤ 50μm, and place it in a heat preservation furnace at 110 - 120°C for heat preservation to prevent the calcined composite powder from absorbing water and getting damp.

[0033] (2) Clean and decontaminate the copper tube and the core material, put the required core material into the copper tube on the assembly table for blank assembly, and fix one end of the copper tube.

[0034] (3) Take out the calcined composite powder from the incubator, add heavy magnesium oxide, with the particle size of heavy magnesium oxide ≥ 45μm (325 mesh) exceeding 90%. Among them, the mass ratio of the calcined composite powder to heavy magnesium oxide is 4:6; After mixing evenly, remove the magnetic metal inclusions in the calcined composite powder, and after moisture discharge treatment at 180 - 200°C, pour it into the gap around the copper core in the copper tube.

[0035] (4) The insulated cable filled with the calcined composite powder is slightly vibrated by a vibrating hammer to further compact the insulating layer, subjected to multiple vertical rolling and diameter reduction, annealed once at 420°C - 600°C, further horizontally reduced in diameter to meet the design specification dimensions, and then annealed a second time at 420°C - 600°C. A protective gas is used to protect the outer surface of the copper tube and copper sheath to be bright. The finished product is wound up for performance testing to obtain a mineral insulated flame-retardant and fire-resistant special cable.

[0036] Example 3

[0037] A method for preparing a special cable for an aluminum-plastic composite film production line is prepared according to the following method:

[0038] 1) Mix the calcined coal gangue powder and the calcined mica powder in a stirrer to fully and evenly mix the two raw materials. There are 55 parts of calcined coal gangue powder and 45 parts of calcined mica powder. Put the mixed powder material into a calcining furnace and calcine it at 900°C. The heating program of the calcining furnace is: heat from room temperature to 400°C for 30 min and hold for 20 min; heat from 400°C to 700°C for 30 min and hold for 30 min; heat from 700°C to 800°C for 5 min and hold for 60 min; heat from 800°C to 900°C for 5 min and hold for 80 min.

[0039] After calcination, it is naturally cooled to 40 - 50°C and taken out of the furnace. The calcined material is dry-ground to a particle size of ≤50 μm and placed in a heat preservation furnace at 110 - 120°C for heat preservation to prevent the calcined composite powder from absorbing water and getting damp.

[0040] (2) Clean and remove dirt from the copper tube and the core material. Place the required core material into the copper tube on an assembly table for blank assembly, and fix one end of the copper tube.

[0041] (3) Take out the calcined composite powder from the insulation box, add heavy magnesium oxide, with a particle size of ≥45 μm (325 mesh) exceeding 90%. Among them, the mass ratio of the calcined composite powder to heavy magnesium oxide is 5:5; after mixing evenly, remove the magnetic metal inclusions in the calcined composite powder, and perform a moisture removal treatment at 180 - 200°C and then pour it into the gap around the copper core in the copper tube.

[0042] (4) The insulated cable filled with the calcined composite powder is slightly vibrated by a vibrating hammer to further compact the insulating layer, subjected to multiple vertical rolling and diameter reduction, annealed once at 420°C - 600°C, further horizontally reduced in diameter to meet the design specification dimensions, and then annealed a second time at 420°C - 600°C. A protective gas is used to protect the outer surface of the copper tube and copper sheath to be bright. The finished product is wound up for performance testing to obtain a mineral insulated flame-retardant and fire-resistant special cable.

[0043] According to the voltage withstand test after bending (1250V for 15 minutes continuously) in Articles 12.2 and 13.2 of GB13033.1-2007, and the standard of the minimum allowable bending radius during and after cable installation, the test results are compared as follows:

[0044]

[0045]

[0046] In accordance with GB13033.1-2007, the comparison results of the technical indicators of the insulated cable in the present invention are as follows:

[0047]

[0048] As can be seen from the above table, compared with the mineral insulated cable of the prior art, the present invention's mineral insulated cable has obvious advantages in three key indicators: the minimum bending radius, insulation resistance, and fire resistance temperature.

[0049] In accordance with GB13033.1-2007, the minimum continuous power supply time of the mineral insulation material in each embodiment of the present invention during a fire is detected, as shown in the following table:

[0050]

[0051] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered within the protection scope of the present invention.

Claims

1. A method for preparing a special cable for an aluminum-plastic composite film production line, characterized in that: Prepared as follows: 1) Mix the calcined gangue powder and calcined mica powder in a blender to make the two raw materials fully mixed and evenly mixed, put the mixed powder into a calcining furnace and calcine at 900°C for 60-90 min; after calcination, naturally cool to 40-50°C and take out of the furnace, dry grind the calcined material to a particle size of ≤50 μm, and place it in a heat preservation furnace to keep warm to prevent the calcined composite powder from absorbing water and getting damp; According to the weight proportion, calcined coal gangue powder is 50-60 parts, calcined mica powder is 40-50 parts; the heating program of the calcining furnace is: room temperature is heated to 400°C for 30 minutes, and maintained for 20 minutes; 400°C is heated to 700°C for 30 minutes, and maintained for 30 minutes; 700°C is heated to 800°C for 5 minutes, and maintained for 60 minutes; 800°C is heated to 900°C for 5 minutes, and maintained for 60-90 minutes; (2) Clean and decontaminate the copper tube and wire core material, put the required wire core material into the copper tube on the assembly table for blank assembly, and fix one end of the copper tube; (3) Take out the calcined composite powder from the heat preservation box and add heavy magnesium oxide, wherein the mass ratio of the calcined composite powder to the heavy magnesium oxide is 4-5:5-6; after mixing evenly, remove the magnetic metal inclusions in the calcined composite powder, and after dehumidification, pour it into the gap around the copper core in the copper tube; the particle size of the heavy magnesium oxide is ≥45 μm and more than 90%; (4) The insulated cable filled with calcined composite powder is further compacted by micro-vibration with a vibrating hammer, and the diameter is reduced by multiple vertical rolling processes. It is annealed at 420°C-600°C for the first time, and further horizontally reduced to meet the design specifications. After that, it is annealed at 420°C-600°C for the second time. The copper tube and copper sheath are protected by protective gas to make the surface bright. The finished product is rolled up for performance testing to obtain mineral insulated flame-retardant and fire-resistant special cables.

2. The method for preparing a special cable for an aluminum-plastic composite film production line according to claim 1, characterized in that: In step (1), the temperature of the holding furnace is 110-120°C.

3. The method for preparing a special cable for an aluminum-plastic composite film production line according to claim 2, characterized in that: In step (3), dehumidification treatment is performed at 180-200°C.

4. A cable prepared by the method for preparing a special cable for an aluminum-plastic composite film production line according to any one of claims 1 to 3.

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