Special cable preparation method for aluminum-plastic composite film production line and cable

Abstract

The invention discloses a preparation method of a special cable for an aluminum-plastic composite film production line, which comprises the following steps of: 1) mixing calcined coal gangue powder and calcined mica powder in a stirrer, sufficiently and uniformly mixing the two raw materials, putting the mixed powder into a calcining furnace, calcining, naturally cooling, and dry-grinding the calcined material until the particle size of the material is less than or equal to 50 microns, so as to obtain a mixed material; and 2) filling, tamping, reducing, annealing and rolling to obtain the cable. The magnesium oxide powder, the calcined coal series kaolin and the calcined mica powder are compounded, the water absorption performance of the material is reduced through ternary composite complementation, meanwhile, the compactness of the insulating material is improved by accurately controlling the proportion of the composite powder, a porcelain column does not need to be pre-sintered, and the problem that the compactness is low due to gas residues is solved; while the production cost is reduced, the electrical, insulating and fire-resistant properties of the mineral insulated cable are improved.

Description

Technical Field

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

[0002] Mineral insulated flame retardant fire-resistant special cables are cables that wrap the copper conductor core with a copper sheath and isolate the conductor and sheath with inorganic insulating materials. The outermost layer is usually a copper sheath. Since all the materials of this cable are made of inorganic materials, the mineral insulated flame retardant fire-resistant special cable itself does not burn, nor does it support combustion or combustion. Since the melting point of copper is 1083℃ and the melting point of inorganic insulating materials is usually as high as 2800℃ or above, mineral insulated flame retardant fire-resistant special cables can continue to maintain power supply in the event of a fire close to the melting point of copper. Even if burned at a high temperature of 1000℃, it will not release smoke, halogens and toxic gases. It is a truly halogen-free and non-toxic fireproof cable. In the production process of composite aluminum-plastic film, due to the high temperature of the electric melting furnace, the conventional cable has poor heat resistance and is very easy to age in a high temperature environment, resulting in reduced insulation performance, short service life, and easy to cause safety accidents. Mineral insulated flame retardant fire-resistant special cables can effectively overcome these shortcomings.

[0003] Mineral insulated flame retardant and fire-resistant special cables usually use magnesium oxide powder as the insulating material. However, magnesium oxide powder is very easy to absorb water, resulting in a decrease in insulation performance. The uniformity and density are difficult to control during the filling process, which seriously affects the bending and extrusion impact resistance of the cable. At present, almost all mineral insulated flame retardant and fire-resistant special cables prepared with multi-component composite inorganic substances as insulating materials need to send the composite insulating material to a press to be pressed into a porcelain column; the pressed porcelain column is placed in a storage box or transported to an electric furnace by a conveyor belt for calcination; the calcined porcelain column is sent to the assembly table, and hot assembly is used during assembly to ensure that it does not absorb moisture; after assembly, repeated drawing and annealing processes are performed until the finished product. Due to the inevitable generation of a large number of pores during the calcination of the porcelain column, the density of the insulating material in the finished product is very low, which cannot maximize the best insulation performance of the composite material.

[0004] The argon arc welding continuous welding magnesium oxide powder filling method is currently the most advanced mineral insulated flame retardant and fire resistant special cable production process. However, magnesium oxide particles are used as insulating filling materials. On the one hand, magnesium oxide is very easy to absorb water and moisture, which reduces the insulation and fire resistance of the material. On the other hand, in order to ensure the density of the magnesium oxide insulation layer during the filling process, large-particle magnesium oxide is usually used for filling, which causes the gaps between the magnesium oxide to become larger, affecting the density of the magnesium oxide insulation layer, thereby reducing the performance of the mineral insulated flame retardant and fire resistant special cable. Summary of the invention

[0005] The purpose of the present invention is to provide a special cable preparation method and cable for aluminum-plastic composite film production line in view of the above-mentioned technical problems. Magnesium oxide powder is compounded with calcined coal-based kaolin and calcined mica powder, and the water absorption performance of the material is reduced through ternary composite complementation. At the same time, the density of the insulating material is improved by accurately controlling the ratio of the composite powder, without pre-burning porcelain columns, avoiding the problem of low density caused by gas residue, reducing production costs, and improving the electrical, insulation and fire-resistant properties of mineral insulated cables. It is used for laying under the furnace, which can improve safety performance, extend service life and reduce maintenance frequency.

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

[0007] 1) Mixing calcined gangue powder and calcined mica powder in a stirrer to fully mix the two raw materials, placing the mixed powder into a calcining furnace for calcining at 900° C. for 60-90 minutes; after calcination, naturally cooling to 40-50° C. and taking out of the furnace, dry grinding the calcined material to a particle size of ≤50 μm, and placing 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 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;

[0009] (3) taking out the calcined composite powder from the heat preservation box, adding 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, removing the magnetic metal inclusions in the calcined composite powder, and pouring it into the gap around the copper core in the copper tube after dehumidification;

[0010] (4) The insulated cable filled with the calcined composite powder is further compacted by micro-vibration with a vibrating hammer, and the diameter is reduced by multiple vertical rolling processes. The cable is annealed at 420°C-600°C for the first time, and the diameter is further reduced horizontally to meet the design specifications. After that, the cable 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 a mineral insulated flame-retardant and fire-resistant special cable.

[0011] In the above scheme: in terms of weight, the calcined coal gangue powder is 50-60 parts and the calcined mica powder is 40-50 parts.

[0012] In the above scheme: in step (1), the temperature raising program of the calcining furnace is: room temperature is raised to 400°C for 30 minutes, and maintained for 20 minutes; 400°C is raised to 700°C for 30 minutes, and maintained for 30 minutes; 700°C is raised to 800°C for 5 minutes, and maintained for 60 minutes; 800°C is raised to 900°C for 5 minutes, and maintained for 60-90 minutes.

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

[0014] In the above scheme: in step (3), dehumidification treatment is carried out at 180-200°C.

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

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

[0017] The calcined gangue of the present invention contains a large amount of mullite crystals, and has good strength, insulation and fire resistance. Unlike other kaolins, the calcined gangue powder does not absorb water, which well solves the problems of insufficient insulation, poor strength and water absorption after subsequent mixing with heavy magnesium oxide. The present invention is calcined at a high temperature of 900°C, which not only destroys the organic matter remaining in the gangue powder, but also removes a large amount of carbon remaining in the gangue powder, and the density of the calcined gangue is greatly improved. The calcined mica powder removes a small amount of structural water at a high temperature of 400-700°C, but does not change the position 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, which reduces the hydrophilicity of the calcined mica powder. At this temperature, although the atomic position of mica has been greatly adjusted, the mineral properties of mica's good insulation and refractory properties are still maintained, while the water absorption of mica is reduced. At the same time, the silicon in the mica powder will promote the formation of mullite crystals in the calcined coal gangue during high-temperature calcination.

[0018] The particle size of heavy magnesium oxide used in the present invention is ≥45μm (325 mesh) for more than 90%. Although the selection of large-particle magnesium oxide is beneficial to improving the density of the insulating layer, it will also cause the gaps between the large-particle magnesium oxide to become larger and more, thereby affecting the insulation of the material. After adding a mixture of calcined coal-based kaolin composite calcined mica powder with a particle size of ≤50μm, the gaps between the heavy magnesium oxide can be effectively filled, thereby greatly improving the density of the material, and the overall performance is that the insulation performance of the cable insulation layer is greatly improved. The mass ratio of the calcined composite mixture added to the heavy magnesium oxide in the patent of the present invention is 4-5:5-6.

[0019] The volume resistivity of the insulated 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 1 order of magnitude, and the high temperature resistance of the insulator is still maintained above 2800℃, which is 300-500℃ higher than similar domestic products, reaching the international advanced level. The minimum continuous power supply time during a fire is 300-360min, which is 240-300min longer than similar domestic products and much longer than the international standard of 60min. The bending and extrusion impact resistance of the mineral insulated special cable of the present invention has been greatly improved, and the minimum bending radius is significantly better than previous similar products.

[0020] The present invention adopts low-cost calcined coal gangue and calcined mica powder to replace nearly half of the heavy magnesium oxide, thereby reducing the cost of the insulation material by more than half while obtaining a high-performance mineral insulated special cable. DETAILED DESCRIPTION

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

[0022] Example 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 gangue powder and calcined mica powder in a blender to make the two raw materials fully mixed and uniform, calcined gangue powder 60 parts, calcined mica powder 40 parts. Put the mixed powder into a calcining furnace and calcine at 900℃. The heating program of the calcining furnace is: room temperature to 400℃, 30min, keep 20min; 400℃ to 700℃, 30min, keep 30min; 700℃ to 800℃, 5min, keep 60min; 800℃ to 900℃, 5min, keep 90min.

[0025] After calcination, the material is naturally cooled to 40-50°C and taken out of the furnace. The calcined material is dry-ground to a particle size of ≤50μm and placed in a 110-120°C insulation furnace to prevent the calcined composite powder from absorbing water and getting damp.

[0026] (2) Clean and decontaminate the copper tube and wire core material, place the required wire 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 heat preservation box, add heavy magnesium oxide, and the particle size of heavy magnesium oxide is ≥45μm (325 mesh) and exceeds 90%. Among them, the mass ratio of calcined composite powder to heavy magnesium oxide is 5:5; after mixing evenly, remove the magnetic metal inclusions in the calcined composite powder, dehumidify it at 180-200℃, and then pour it into the gap around the copper core in the copper tube.

[0028] (4) The insulated cable filled with the calcined composite powder is further compacted by micro-vibration with a vibrating hammer, and the diameter is reduced by multiple vertical rolling processes. The cable is annealed at 420°C-600°C for the first time, and the diameter is further reduced horizontally to meet the design specifications. After that, the cable is annealed at 420°C-600°C for the second time. The copper tube and copper sheath are protected by protective gas (nitrogen or other inert gas) to make the surface bright. The finished product is rolled up for performance testing to obtain a mineral insulated flame-retardant and fire-resistant special cable.

[0029] Example 2

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

[0031] 1) Mix calcined gangue powder and calcined mica powder in a blender to make the two raw materials fully mixed and uniform, calcined gangue powder 50 parts, calcined mica powder 50 parts. Put the mixed powder into a calcining furnace and calcine at 900℃. The heating program of the calcining furnace is: room temperature to 400℃, 30min, keep 20min; 400℃ to 700℃, 30min, keep 30min; 700℃ to 800℃, 5min, keep 60min; 800℃ to 900℃, 5min, keep 60min.

[0032] After calcination, the material is naturally cooled to 40-50°C and taken out of the furnace. The calcined material is dry-ground to a particle size of ≤50μm and placed in a 110-120°C insulation furnace to prevent the calcined composite powder from absorbing water and getting damp.

[0033] (2) Clean and decontaminate the copper tube and wire core material, place the required wire 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 heat preservation box, add heavy magnesium oxide, and the particle size of heavy magnesium oxide is ≥45μm (325 mesh) exceeding 90%. Among them, the mass ratio of calcined composite powder to heavy magnesium oxide is 4:6; after mixing evenly, remove the magnetic metal inclusions in the calcined composite powder, dehumidify it at 180-200℃, and then 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 further compacted by micro-vibration with a vibrating hammer, and the diameter is reduced by multiple vertical rolling processes. The cable is annealed at 420°C-600°C for the first time, and the diameter is further reduced horizontally to meet the design specifications. After that, the cable 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 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 calcined gangue powder and calcined mica powder in a blender to make the two raw materials fully mixed and uniform, calcined gangue powder 55 parts, calcined mica powder 45 parts. Put the mixed powder into a calcining furnace and calcine at 900℃. The heating program of the calcining furnace is: room temperature to 400℃, 30min, keep 20min; 400℃ to 700℃, 30min, keep 30min; 700℃ to 800℃, 5min, keep 60min; 800℃ to 900℃, 5min, keep 80min.

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

[0040] (2) Clean and decontaminate the copper tube and wire core material, place the required wire core material into the copper tube on the assembly table for blank assembly, and fix one end of the copper tube.

[0041] (3) Take out the calcined composite powder from the heat preservation box, add heavy magnesium oxide, and the particle size of heavy magnesium oxide is ≥45μm (325 mesh) and exceeds 90%. Among them, the mass ratio of calcined composite powder to heavy magnesium oxide is 5:5; after mixing evenly, remove the magnetic metal inclusions in the calcined composite powder, dehumidify it at 180-200℃, 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 further compacted by micro-vibration with a vibrating hammer, and the diameter is reduced by multiple vertical rolling processes. The cable is annealed at 420°C-600°C for the first time, and the diameter is further reduced horizontally to meet the design specifications. After that, the cable 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 a mineral insulated flame-retardant and fire-resistant special cable.

[0043] According to the withstand voltage test after bending (1250V for 15 minutes) in Article 12.2 and Article 13.2 of GB13033.1-2007, the test results are compared as follows:

[0044]

[0045]

[0046] According to GB13033.1-2007, the comparison results of the technical indicators of the insulated cables in the present invention are as follows:

[0047]

[0048] It can be seen from the above table that, compared with the mineral insulated cables in the prior art, the mineral insulated cables of the present invention have obvious advantages in terms of the three key indicators of minimum bending radius, insulation resistance and fire resistance temperature.

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

[0050]

[0051] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by 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) Mixing calcined gangue powder and calcined mica powder in a stirrer to fully mix the two raw materials, placing the mixed powder into a calcining furnace for calcining at 900° C. for 60-90 minutes; after calcination, naturally cooling to 40-50° C. and taking out of the furnace, dry grinding the calcined material to a particle size of ≤50 μm, and placing it in a heat preservation furnace for heat preservation to prevent the calcined composite powder from absorbing water and getting damp; (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) taking out the calcined composite powder from the heat preservation box, adding 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, removing the magnetic metal inclusions in the calcined composite powder, and pouring it into the gap around the copper core in the copper tube after dehumidification; (4) The insulated cable filled with the calcined composite powder is further compacted by micro-vibration with a vibrating hammer, and the diameter is reduced by multiple vertical rolling processes. The cable is annealed at 420°C-600°C for the first time, and the diameter is further reduced horizontally to meet the design specifications. After that, the cable 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 a mineral insulated flame-retardant and fire-resistant special cable.

2. The method for preparing a special cable for an aluminum-plastic composite film production line according to claim 1, characterized in that: In terms of weight, the calcined coal gangue powder is 50-60 parts and the calcined mica powder is 40-50 parts.

3. A method for preparing a special cable for an aluminum-plastic composite film production line according to claim 1 or 2, characterized in that: In step (1), the temperature raising program of the calcining furnace is as follows: room temperature is raised to 400°C for 30 minutes and maintained for 20 minutes; 400°C is raised to 700°C for 30 minutes and maintained for 30 minutes; 700°C is raised to 800°C for 5 minutes and maintained for 60 minutes; 800°C is raised to 900°C for 5 minutes and maintained for 60-90 minutes.

4. The method for preparing a special cable for an aluminum-plastic composite film production line according to claim 3, characterized in that: In step (1), the temperature of the holding furnace is 110-120°C.

5. The method for preparing an insulated fireproof cable by filling calcined coal-based kaolin composite magnesium oxide powder according to claim 4, characterized in that: In step (3), dehumidification treatment is performed at 180-200°C.

6. The method for preparing an insulated fireproof cable by filling calcined coal-based kaolin composite magnesium oxide powder according to claim 5, characterized in that: The particle size of heavy magnesium oxide is ≥45μm (325 mesh) and exceeds 90%.

7. 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 6.

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