Medium-voltage power cable, production line of medium-voltage power cable and production method of medium-voltage power cable

Abstract

The invention relates to a medium-voltage power cable, a production line and a production method, and the cable comprises a conductor, a first semi-conductive conductor shielding layer, an insulating layer, a second semi-conductive insulating shielding layer, a semi-conductive water-blocking tape buffer layer, a metal shielding layer and an outer sheath layer, and the first semi-conductive conductor shielding layer, the insulating layer, the second semi-conductive insulating shielding layer and the semi-conductive water-blocking tape buffer layer are coated outside the conductor. The first semi-conductive conductor shielding layer, the insulating layer and the second semi-conductive insulating shielding layer are made of a polypropylene insulating material and do not need to be crosslinked, so that the energy consumption is reduced and the production period is shortened. And the metal shielding layer adopts a single-sided film-coated aluminum strip layer, comprises an aluminum strip and an EAA-PE composite film, and is attached to the polyethylene sheath. The production device comprises a first line body, a second line body and a connecting line body which are arranged in a U shape, and continuous production is achieved. The production method comprises the following steps: forming the insulated wire core by using the CCV three-layer co-extrusion equipment, cooling, adding each layer through the longitudinal coating device, and finally forming the medium-voltage power cable. By simplifying the production process, the production efficiency is improved, the cost is reduced, and meanwhile, the influence on the environment is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of cables, and in particular to a medium-voltage power cable, a production line of the medium-voltage power cable and a production method thereof. Background Art

[0002] According to product standards, medium voltage power cables usually refer to power cables from 3.6 / 6kV to 26 / 35kV. The product implementation standards include GB / T 12706.2, GB / T 12706.3, IEC 60502-2, etc. Its insulation material usually uses cross-linked polyethylene. The traditional production process steps of the above-mentioned power cables include: conductor production, insulation layer production (including conductor shielding layer production, cross-linked polyethylene insulation layer production, insulation shielding layer production), metal shielding layer production and outer sheath production. The existing production method of power cables has at least the following defects: In the traditional production process of medium-voltage power cables, each production process needs to be turned around or paused after completion before the next process can be carried out. In other words, continuous production cannot be achieved between the various processes. Specifically: The production process of the insulation layer in the traditional production process of medium-voltage power cables is: the CCV three-layer co-extrusion equipment used for cross-linked polyethylene materials is used to produce the insulation layer (including the conductor shielding layer, the cross-linked polyethylene insulation layer, and the insulation shielding layer), and then the insulation layer is cooled and degassed. Since cross-linked polyethylene needs to react at high temperature of 400°C and high pressure during the production process, the cross-linking reaction time is long; in the production process of cross-linked polyethylene, chemical cross-linking agents (such as DCP) are used to react with polyethylene, and free radicals are formed under the action of heat, so that active points are generated on the carbon chain of the polymer, and carbon-carbon cross-linking is generated to form a network structure, but at the same time, by-products such as methane, water, methyl styrene, cumyl alcohol and acetophenone are also generated. These by-products are contained in the insulation layer. If there is no high pressure constraint, these by-products will form bubbles in the molten insulation, which will lead to partial discharge and voltage breakdown. Therefore, the cross-linked polyethylene insulation layer needs to be cooled and degassed. The cable production process needs to stay in the cross-linked polyethylene insulation layer production process for at least 24 hours before it can enter the next process.

[0003] In addition, the CCV three-layer co-extrusion production line used in the above insulation production consumes a lot of energy and has high carbon emissions. The production of cross-linked polyethylene insulation layer needs to be carried out under high temperature (about 400°C) and high pressure (5Mpa), which requires the heating system of the production line to provide enough heat to maintain this temperature, thereby consuming a lot of energy. Due to the high energy consumption of the CCV three-layer co-extrusion production line, the corresponding carbon emissions will also increase.

[0004] In traditional medium-voltage cable production, the metal shielding layer is usually made of copper wire or copper tape. For copper tape shielding, the production process involves using a copper tape shielding wrapping machine to spirally wind the copper tape around the insulated wire core. Due to equipment capacity limitations, the production of copper tape shielding usually needs to be stopped when it does not exceed 500 meters in order to replace the new copper tape coil barrel. For copper wire shielding, a copper wire winding shielding machine is used to spirally wind 6 to 100 (depending on the product size) electrical annealed copper wires around the insulated wire core. Equipment capacity limitations require shutdowns approximately every 600 meters to replace new copper wire coil barrels. Since the copper tape shielding or copper wire shielding production process requires shutdown, this process usually acts independently and cannot be connected in series with other production processes.

[0005] In addition, since copper tape and copper wire are wrapped around the insulated wire core to form a metal shielding layer, the copper tape shielding equipment and the copper wire winding shielding equipment need to be equipped with a rotating mechanism to provide power for winding the copper wire and copper tape. The rotating mechanism needs to be equipped with an auxiliary mechanism to control parameters such as rotation speed, line speed, and tension. Therefore, it occupies a large area and is more complicated to operate.

[0006] Furthermore, the above-mentioned metal shielding layer uses copper wire or copper tape. Although copper has excellent conductivity, its density and price are also expensive. Therefore, using copper wire or copper tape as the metal shielding layer increases the production cost of the power cable.

[0007] In summary, most of the processes in the traditional medium-voltage power cable production process have a long production time, so each process can only be operated independently, and then the semi-finished products made in each process are taken to the next process for further preparation. In other words, the various processes in the traditional medium-voltage power cable production process cannot be seamlessly connected and then connected in series to form a production line with continuous production of each process. If each process must be connected in series, it will inevitably cause a long-term stagnation of the production line and waste of resources.

[0008] In addition, based on the traditional medium-voltage power cable production process, the cross-linked polyethylene insulation layer consumes a lot of energy, the copper tape shielding equipment and copper wire winding shielding equipment are bulky, and the copper tape cost is high, which increases the cost and limitations of medium-voltage power cable production. Summary of the invention

[0009] The embodiments of the present application provide a medium voltage power cable, a production device for a medium voltage power cable and a production method thereof to solve the technical problem in the prior art that most processes have a long production time and cannot be seamlessly connected to form a continuous production line.

[0010] To solve the above technical problems, an embodiment of the present invention provides a medium-voltage power cable, comprising: a conductor, a first semi-conductive conductor shielding layer wrapped outside the conductor, an insulating layer wrapped outside the first semi-conductive conductor shielding layer, a second semi-conductive insulating shielding layer wrapped outside the insulating layer, a semi-conductive resistance water-tightening tape buffer layer wrapped outside the second semi-conductive insulating shielding layer, a metal shielding layer wrapped around the semi-conductive resistance water-tightening tape buffer layer, and an outer sheath layer wrapped outside the metal shielding layer, wherein the first semi-conductive conductor shielding layer, the insulating layer and the second semi-conductive insulating shielding layer are respectively made of polypropylene insulating materials.

[0011] In one embodiment of the present invention, the metal shielding layer includes a single-sided film-coated aluminum tape layer, and the single-sided film-coated aluminum tape layer includes an aluminum tape and an EAA-PE composite film disposed on the aluminum tape.

[0012] In one embodiment of the present invention, the outer sheath layer is a polyethylene sheath, and the EAA-PE composite film of the single-sided aluminum tape layer is bonded to the polyethylene sheath.

[0013] The embodiment of the present invention further provides a production device for a medium voltage power cable, comprising: a first wire body, a second wire body and a connecting wire body, wherein the first wire body and the second wire body are arranged in parallel and at an interval, the flow direction of the first wire body is opposite to the flow direction of the second wire body, the connecting wire body connects the end of the first wire body and the initial end of the second wire body, and the first wire body, the second wire body and the connecting wire body form a U-shaped wire body; The first wire body is provided with a CCV three-layer co-extrusion device and a first cooling device, the CCV three-layer co-extrusion device is used to form a first semi-conductive conductor shielding layer, an insulating layer and a second semi-conductive insulating shielding layer using polypropylene material and wrap them outside the conductor in a three-layer co-extrusion manner to form an insulated wire core, and the first cooling device is used to cool the insulated wire core; The second wire body is provided with a first longitudinal covering device, a second longitudinal covering device and a cable sheath extruder, the first longitudinal covering device is used to longitudinally cover the semiconducting water-resistant tape buffer layer outside the insulating wire core, the second longitudinal covering device is used to cover the metal shielding layer outside the semiconducting water-resistant tape buffer layer, and the cable sheath extruder is used to extrude and cover an outer sheath layer outside the metal shielding layer to form a medium voltage power cable; and, The connecting wire body includes a reel, which is used to temporarily store the insulated wire core transmitted from the first wire body and transmit the insulated wire core to the second wire body.

[0014] In one embodiment of the present invention, the reel comprises two spaced-apart and horizontally arranged guide wheels, and a plurality of wire grooves are arranged on the guide wheels.

[0015] In one embodiment of the present invention, the first cooling device comprises a cooling water trough, and the cooling water trough comprises three sections of trough bodies, and the water temperature of each section of the trough body is independently set.

[0016] The embodiment of the present invention further provides a method for producing a medium voltage power cable, which is implemented based on the above-mentioned medium voltage power cable production device, and the production method comprises the following steps: Using CCV three-layer co-extrusion equipment to extrude polypropylene material and form a first semi-conductive conductor shielding layer, an insulating layer and a second semi-conductive insulating shielding layer, and wrapping them outside the conductor in a three-layer co-extrusion manner to form an insulated wire core; Using a first cooling device to cool the insulated wire core; The insulated wire core after cooling is passed around the reel and then bent, and then enters the first longitudinal covering device after being bent; Using a first longitudinal covering device to longitudinally cover the semiconductive water-resistant tape buffer layer outside the insulating wire core; The metal shielding layer is covered outside the semiconducting water-resistant tape buffer layer by using a second longitudinal covering device; A cable sheath extruder is used to extrude and coat an outer sheath layer on the metal shielding layer to form a medium voltage power cable.

[0017] In one embodiment of the present invention, the temperature of the first section of the cooling water trough is set at 65-75°C, and the entire insulated wire core is completely immersed in the water trough; the temperature of the second section of the cooling water trough is set at 50-60°C; and the temperature of the third section of the cooling water trough is set at 20-30°C.

[0018] In one embodiment of the present invention, the semiconducting water-resistant tape buffer layer is completely covered on the surface of the insulating wire core by longitudinal coating, and the overlap rate between two adjacent pieces of the semiconducting water-resistant tape buffer layer is not less than 10%; and / or, The metal shielding layer is completely covered on the semiconducting water-resistant tape buffer layer by longitudinal covering, the overlapping width of two adjacent metal shielding layers is not less than 5 mm, and the overlapping parts are bonded by high-temperature resistant hot melt adhesive.

[0019] In one embodiment of the present invention, the metal shielding layer includes a single-sided coated aluminum tape layer, the single-sided coated aluminum tape layer includes an aluminum tape and an EAA-PE composite film arranged on the aluminum tape, the outer sheath layer adopts a polyethylene sheath, and when the polyethylene sheath is extruded by the cable sheath extruder, the high temperature of the polyethylene sheath extrusion process causes the polyethylene sheath to self-bond with the EAA-PE composite film of the single-sided coated aluminum tape layer and form a bonding layer; And / or, the production method of the medium voltage power cable further comprises: water cooling the medium voltage power cable formed by extruding and coating an outer sheath layer on the metal shielding layer using a cable sheath extruder, and finally rolling it up.

[0020] The above technical solution of the present invention has at least the following advantages compared with the prior art: The first semi-conductive conductor shielding layer, the insulating layer, and the second semi-conductive insulating shielding layer of the medium-voltage power cable provided by the present invention all use polypropylene insulating material, which does not require cross-linking. Compared with traditional cross-linked polyethylene materials, polypropylene insulating materials have lower energy consumption and shorter production cycles during the production process. At the same time, since the high-voltage cross-linking and degassing processes are omitted during the production process, the material cost and production equipment cost are also relatively low. In addition, compared with traditional cross-linked polyethylene materials, the carbon emissions of polypropylene materials throughout their life cycle are reduced, which significantly reduces the impact on the environment. In addition, due to its characteristics as an environmentally friendly thermoplastic material, polypropylene insulating materials have better recyclability, further reducing the environmental burden, and are an economical and environmentally friendly choice of cable insulation materials.

[0021] The medium voltage power cable preparation method of the present invention uses a CCV three-layer co-extrusion device to wrap the first semi-conductive conductor shielding layer, the insulating layer and the second semi-conductive insulating shielding layer around the conductor in a three-layer co-extrusion manner, thereby forming an insulating core. Compared with the cross-linked polyethylene (XLPE) material used in the insulating layer in the traditional technology, the polypropylene insulating material used in the present invention does not need to undergo a high temperature and high pressure cross-linking process, which not only reduces production energy consumption, but also shortens the production cycle; the polypropylene material used in the present invention does not produce degassing during the production process, thereby further shortening the production cycle. The insulating core forming process can be directly connected to the subsequent process, thereby forming a continuous production line without interruption, and forming a set of continuous production processes. Such a continuous production method not only saves a lot of time, avoids the turnover, upper and lower disks between processes, but also greatly reduces energy loss and improves production efficiency, thereby achieving significant improvements in economic and environmental benefits. Through this innovative method, the entire production process of power cables can be realized in production lines.

[0022] The metal shielding layer used in the medium-voltage power cable preparation method of the present invention is a single-sided coated aluminum tape layer, which adopts the method of longitudinally coating the aluminum tape, and there is no need to configure a rotating mechanism to provide winding force. The second longitudinal coating device can carry a relatively large aluminum tape roll at one time, and the process of coating the aluminum tape does not require shutdown, thereby ensuring the smooth connection between this process and the subsequent process, forming a continuous production line without interruption. This continuous production method not only saves a lot of time, avoids the turnover, upper and lower discs between processes, but also significantly reduces energy loss and improves production efficiency. In addition, the second longitudinal coating device only needs to control the tension and rely on the traction provided by the sheath extruder to achieve movement, so its volume is relatively small. Compared with traditional copper materials, the use of aluminum tape as a metal shielding layer has a cost advantage, which further reduces production costs.

[0023] The medium-voltage power cable production line provided by the present invention can realize continuous production, reduce energy consumption and material costs, and use polypropylene insulation materials to eliminate high-voltage cross-linking and degassing processes, while reducing environmental impact and improving the recyclability of materials. The U-shaped production line design saves space, improves process flow efficiency, simplifies the production process, avoids time waste and quality risks caused by operations such as turnover and loading and unloading, improves production efficiency and product quality, reduces production costs, and enhances the flexibility and adaptability of the production line. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein Figure 1 It is a structural schematic diagram of the medium voltage power cable in the present invention; Figure 2 is a schematic diagram of a method for producing a medium voltage power cable in the present invention; Figure 3 It is a top view of the reel in the present invention.

[0025] Explanation of the reference numerals in the specification: 11. conductor; 12. first semi-conductive conductor shielding layer; 13. insulating layer; 14. second semi-conductive insulating shielding layer; 15. semiconductor resistance water-tightening tape buffer layer; 16. metal shielding layer; 17. outer sheath layer; 20. first wire body; 21. CCV three-layer co-extrusion equipment; 22. first cooling device; 30. second wire body; 31. first longitudinal covering device; 32. second longitudinal covering device; 33. cable sheath extruder; 40. connecting wire body; 41. reel; 411. guide wheel. DETAILED DESCRIPTION

[0026] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention. Embodiment 1:

[0027] See also Figure 1 As shown, embodiment 1 of the present invention provides a medium-voltage power cable, comprising: a conductor 11, a first semiconductive conductor shielding layer 12 wrapped outside the conductor 11, an insulating layer 13 wrapped outside the first semiconductive conductor shielding layer 12, a second semiconductive insulating shielding layer 14 wrapped outside the insulating layer 13, a semiconductive resistance water-tightening tape buffer layer 15 wrapped outside the second semiconductive insulating shielding layer 14, a metal shielding layer 16 wrapped around the semiconductive resistance water-tightening tape buffer layer 15, and an outer sheath layer 17 wrapped outside the metal shielding layer 16, wherein the first semiconductive conductor shielding layer 12, the insulating layer 13 and the second semiconductive insulating shielding layer 14 are respectively made of polypropylene insulating materials, and the conductor 11 is made of aluminum material.

[0028] The first semi-conductive conductor shielding layer 12, the insulating layer 13, and the second semi-conductive insulating shielding layer 14 of the medium-voltage power cable provided in Example 1 of the present invention are all made of polypropylene insulating material, which does not require cross-linking, high-temperature and high-pressure vulcanization, and degassing treatment. Compared with traditional cross-linked polyethylene materials, polypropylene insulating materials have lower energy consumption and shorter production cycles during the production process. At the same time, since the high-voltage cross-linking and degassing processes are omitted in the production process, the material cost and production equipment cost are also relatively low. In addition, compared with traditional cross-linked polyethylene materials, the carbon emissions of polypropylene materials throughout their life cycle are reduced, which significantly reduces the impact on the environment. In addition, due to its characteristics as an environmentally friendly thermoplastic material, polypropylene insulating materials have better recyclability, further reducing the environmental burden, and are an economical and environmentally friendly choice of cable insulation materials.

[0029] In one embodiment of the present invention, the metal shielding layer 16 includes a single-sided coated aluminum tape layer, and the single-sided coated aluminum tape layer includes an aluminum tape and an EAA-PE composite film disposed on the aluminum tape. The aluminum tape is disposed close to the semiconductor water-repellent tape buffer layer 15, and the EAA-PE composite film is disposed close to the outer sheath layer 17. EAA-PE refers to a combination of ethylene acrylic acid copolymer (EAA for short) and polyethylene (PE for short). Compared with traditional copper materials as metal shielding layers, the use of aluminum tape as a metal shielding layer is inexpensive and reduces production costs.

[0030] In one embodiment of the present invention, the outer sheath layer 17 is a polyethylene sheath, and the EAA-PE composite film with a single-sided aluminum tape layer is bonded to the polyethylene sheath. The outer sheath layer 17 is a polyethylene sheath, and when the polyethylene sheath is extruded by the cable sheath extruder 33, the polyethylene sheath and the EAA-PE composite film are self-bonded to form an adhesive layer due to the high temperature during the polyethylene sheath extrusion process. Embodiment 2:

[0031] See also Figure 2 As shown, Embodiment 2 of the present invention further provides a production device for a medium voltage power cable, comprising: a first wire body 20, a second wire body 30 and a connecting wire body 40, wherein the first wire body 20 and the second wire body 30 are arranged in parallel and at intervals, the flow direction of the first wire body 20 is opposite to the flow direction of the second wire body 30, the connecting wire body 40 connects the end of the first wire body 20 and the initial end of the second wire body 30, and the first wire body 20, the second wire body 30 and the connecting wire body 40 form a U-shaped wire body; The first wire body 20 is provided with a CCV three-layer co-extrusion device 21 and a first cooling device 22. The CCV three-layer co-extrusion device 21 is used to form a first semi-conductive conductor shielding layer 12, an insulating layer 13 and a second semi-conductive insulating shielding layer 14 using polypropylene material and wrap them outside the conductor 11 in a three-layer co-extrusion manner to form an insulated wire core. The first cooling device 22 is used to cool the insulated wire core. The second wire body 30 is provided with a first longitudinal covering device 31, a second longitudinal covering device 32 and a cable sheath extruder 33, the first longitudinal covering device 31 is used to longitudinally cover the semiconducting water-resistant tape buffer layer 15 outside the insulating core, the second longitudinal covering device 32 is used to cover the metal shielding layer 16 outside the semiconducting water-resistant tape buffer layer 15, and the cable sheath extruder 33 is used to extrude and cover an outer sheath layer 17 outside the metal shielding layer 16 to form a medium voltage power cable; and, The connecting wire body 40 includes a reel 41, and the reel 41 is used to temporarily store the insulated wire cores transferred from the first wire body and transfer the insulated wire cores to the second wire body.

[0032] The reason why the medium-voltage power cable production line provided in Example 2 of the present invention can achieve continuous production is that this embodiment adopts a CCV three-layer co-extrusion device, which can continuously extrude the polypropylene material to continuously form the first semi-conductive conductor shielding layer 12, the insulating layer 13 and the second semi-conductive insulating shielding layer 14, and coat these layers on the conductor 11 at one time to form an insulated wire core. Since the polypropylene material does not require cross-linking, vulcanization and degassing, the production cycle is greatly shortened, and it can smoothly transition to the next process. The insulated wire core is then rapidly cooled by a cooling device, and then continuously enters the longitudinal coating device to coat the semi-conductive water-resistant tape buffer layer 15 and the metal shielding layer 16 in turn. In this step, the longitudinal coating device can load a large volume of material rolls without stopping due to changing the material rolls, ensuring the continuity of production. Finally, the cable sheath extruder 33 continuously extrude the polyethylene sheath layer to complete the final coating of the cable. The entire production process does not require additional turnover or pauses between the processes, and realizes continuous production from the conductor 11 to the finished product, reduces energy consumption, and improves production efficiency and output. At the same time, due to the reduction of carbon emissions throughout the life cycle of polypropylene materials, the impact on the environment is significantly reduced. In addition, due to its environmentally friendly thermoplastic material characteristics, polypropylene insulation materials have better recyclability, further reducing the environmental burden.

[0033] See also Figure 3 As shown, in one embodiment of the present invention, the reel 41 includes two spaced and horizontally arranged guide wheels 411, and a plurality of wire grooves are arranged on the guide wheels 411. The insulated wire core cooled by the cooling device of the first wire body is wound back and forth on the wire grooves of the two guide wheels 411, thereby increasing the capacity of the reel 41 to accommodate the insulated wire core.

[0034] The design of the reel 41 can temporarily store the insulated wire cores transmitted from the first wire body. This step is crucial and solves a potential bottleneck problem in the production process: when the processing speed of the first wire body is higher than the processing speed of the second wire body, the second wire body may not have enough time to process all the insulated wire cores. The temporary storage function of the reel 41 can avoid production interruptions caused by speed mismatch.

[0035] In addition, the presence of the reel 41 allows a speed balance to be achieved between the first line and the second line. This speed balance ensures that both lines can maintain continuous operation, thereby improving overall production efficiency and process consistency. In this way, the reel 41 not only improves the flexibility of material handling, but also reduces material waste and production delays caused by speed differences, providing strong support for the stable operation of the production line.

[0036] In one embodiment of the present invention, the first cooling device 22 includes a cooling water tank, which includes three sections of tank bodies, and the water temperature of each section of the tank body is set independently. The temperature of the first section of the cooling water tank is set at 65 to 75°C, and the entire insulating core is completely immersed in the water tank. The insulating core is slowly cooled by water at 65 to 75 degrees Celsius to avoid excessive rapid cooling and uneven crystallization of polypropylene insulation. The temperature of the second section of the cooling water tank is set at 50 to 60°C. After the insulating core passes through the first section of the water tank, it is further cooled and shaped here. The temperature of the third section of the cooling water tank is set at 20 to 30°C, and the insulating core completes the final cooling here. Embodiment 3:

[0037] See also Figure 2 As shown, Embodiment 3 of the present invention further provides a method for producing a medium voltage power cable, which is implemented based on the production device for the medium voltage power cable in Embodiment 2, and the production method comprises the following steps: The polypropylene material is extruded by a CCV three-layer co-extrusion device 21 to form a first semi-conductive conductor shielding layer 12, an insulating layer 13 and a second semi-conductive insulating shielding layer 14, and the three-layer co-extrusion method is used to cover the conductor 11 to form an insulated wire core, wherein the thickness of the extruded first semi-conductive conductor shielding layer 12 is 0.3 mm to 0.6 mm, the thickness of the extruded insulating layer 13 is 4.85 mm to 5.5 mm, and the thickness of the extruded second semi-conductive insulating shielding layer 14 is 0.3 mm to 0.6 mm; Using the first cooling device 22 to cool the insulated wire core; The insulated wire core after cooling is wound around the reel 41 and then bent, and then enters the first longitudinal covering device 31; The first longitudinal covering device 31 is used to longitudinally cover the semiconducting water-resistant tape buffer layer 15 outside the insulating wire core; The metal shielding layer 16 is coated on the outside of the semiconducting water-resistant tape buffer layer 15 by using the second longitudinal coating device 32; A cable sheath extruder 33 is used to extrude and coat an outer sheath layer 17 on the outside of the metal shielding layer 16, thereby forming a medium voltage power cable.

[0038] The method for preparing a medium-voltage power cable in an embodiment of the present invention uses a CCV three-layer co-extrusion device to wrap the first semi-conductive conductor shielding layer 12, the insulating layer 13 and the second semi-conductive insulating shielding layer 14 around the conductor 11 in a three-layer co-extrusion manner, thereby forming an insulating core. Compared with the cross-linked polyethylene (XLPE) material used in the insulating layer 13 in the conventional technology, the polypropylene insulating material used in the present invention does not need to undergo a high temperature and high pressure cross-linking process, which not only reduces production energy consumption, but also shortens the production cycle. The polypropylene material used in the present invention does not need to be vulcanized and degassed during the production process, thereby further shortening the production cycle, so that the insulating core forming process can be directly connected to the subsequent process, thereby forming a continuous production line without interruption, and forming a set of continuous production processes. Such a continuous production method not only saves a lot of time, avoids the turnover, upper and lower disks between processes, but also greatly reduces energy loss and improves production efficiency. Through this innovative method, the entire production process of the power cable can achieve efficient production line operation, solving the technical problem that the existing technology cannot produce line operation.

[0039] The metal shielding layer 16 used in the method for preparing the medium-voltage power cable in this embodiment is a single-sided coated aluminum strip layer, which adopts the method of longitudinally coating the aluminum strip, and does not need to be configured with a rotating mechanism to provide winding force like traditional copper strips or copper wires. The second longitudinal coating device 32 can carry a large volume of aluminum strip rolls at one time, and the process of coating the aluminum strip does not need to be stopped, thereby ensuring the smooth connection between this process and the subsequent process, thereby forming a continuous production line without interruption. This continuous production method not only saves a lot of time, avoids the turnover, upper and lower discs between processes, but also significantly reduces energy loss and improves production efficiency. In addition, the second longitudinal coating device 32 only needs to control the tension and relies on the traction provided by the sheath extruder to achieve movement, so its volume is relatively small. Compared with the traditional copper material as the metal shielding layer, the use of aluminum strip as the metal shielding layer is low in price, which further reduces the production cost.

[0040] In one embodiment of the present invention, the cooling device uses a water trough divided into three sections, each section is about 15m long; the temperature of the first section of the cooling water trough is set at 65-75°C, and the entire insulated wire core is completely immersed in the water trough; the temperature of the second section of the cooling water trough is set at 50-60°C; the temperature of the third section of the cooling water trough is set at 20-30°C.

[0041] The temperature of the first section of the cooling water tank is set at 65-75°C. The entire insulated wire core is completely immersed in the water tank. The insulated wire core is slowly cooled by the water at 65-75°C to avoid excessive quenching and uneven crystallization of the polypropylene insulation material. The temperature of the second section of the cooling water tank is set at 50-60°C. After the insulated wire core passes through the first section of the water tank, it is further cooled and shaped here, which helps the material to be shaped, reduces thermal stress, and thus improves the structural stability of the insulated wire core. The temperature of the third section of the cooling water tank is set at 20-30°C. The insulated wire core completes the final cooling here. This temperature range helps the insulated wire core reach room temperature, ensures the final performance of the material, and provides suitable temperature conditions for subsequent processing steps (such as coating the semi-conductive resistor water belt buffer layer and the metal shielding layer).

[0042] In one embodiment of the present invention, the first longitudinal covering device 31 is used to completely cover the surface of the insulating wire core with the semiconducting tape buffer layer 15 by longitudinal covering, and the overlap rate between two adjacent pieces of the semiconducting tape buffer layer 15 is not less than 10%. The first longitudinal covering device 31 includes an active tape release device, a tension adjustment system, and a longitudinal covering mold. The active tape release device can be used to actively release the semiconducting tape, the tension adjustment system can adjust the tension of the material tape, and the longitudinal covering mold can be used to wrap the semiconducting tape on the surface of the insulating wire core. The active tape release device, the tension adjustment system, and the longitudinal covering mold included in the first longitudinal covering device 31 are all conventional devices in the prior art and will not be described in detail here.

[0043] The second longitudinal covering device 32 is used to completely cover the metal shielding layer 16 on the coated semiconductor resistance water-conducting tape buffer layer 15 in a longitudinal covering manner. The overlapping width of the two adjacent metal shielding layers 16 is not less than 5 mm, and the overlapping part is bonded with high-temperature resistant hot melt adhesive. The second longitudinal covering device 32 includes an active tape release device, a tension adjustment system, a longitudinal covering mold and a hot melt adhesive dripping system. The active tape release device can be used to actively release the metal shielding tape, the tension of the metal shielding tape can be adjusted by the tension adjustment system, the metal shielding tape can be wrapped on the surface of the insulating wire core by the longitudinal covering mold, and the hot melt adhesive dripping system can be used to drip hot melt adhesive on the overlapping part between the two adjacent metal shielding tapes to achieve bonding at the overlapping part.

[0044] Specifically, the insulated wire core is pulled forward by a traction device equipped with a sheath extruder, the semiconductor resistive water tape is packaged in a reel and placed vertically under the insulated wire core, and the semiconductor resistive water tape is unwound by an active unwinding device; the semiconductor resistive water tape passes through a coating mold to longitudinally coat the insulating wire core with the material tape to achieve complete coverage of the surface of the insulating wire core; the insulated wire core coated with the semiconductor resistive water tape then enters the single-sided coated aluminum tape longitudinal coating process, the active unwinding device and principle of the single-sided coated aluminum tape correspond to the active unwinding device and principle of the semiconductor resistive water tape, the only difference is the added hot melt glue dripping device, which is a common device in the glue dripping field, by dripping hot melt glue on the edge of one side of the single-sided coated aluminum tape, when the single-sided coated aluminum tape passes through the longitudinal coating mold, the hot melt glue can firmly adhere to the overlapping part to form a stable tubular structure.

[0045] In one embodiment of the present invention, the metal shielding layer 16 includes a single-sided coated aluminum tape layer, the single-sided coated aluminum tape layer includes an aluminum tape and an EAA-PE composite film arranged on the aluminum tape, and the outer sheath layer 17 adopts a polyethylene sheath. When the polyethylene sheath is extruded by a cable sheath extruder 33, due to the high temperature of the polyethylene sheath extrusion process, the polyethylene sheath and the EAA-PE composite film of the single-sided coated aluminum tape layer self-bond to form a bonding layer.

[0046] By setting an EAA-PE composite film on the single-sided coated aluminum tape layer and using high temperature to make the polyethylene sheath and the EAA-PE composite film self-bonded during the extrusion of the polyethylene sheath, a strong bond between the metal shielding layer 16 and the outer sheath layer 17 is achieved, forming a stable bonding layer. This structure not only enhances the mechanical protection performance of the cable and prevents the penetration of moisture and gas, but also eliminates additional bonding steps, simplifies the production process, and improves production efficiency. At the same time, since the bonding process is naturally completed during the extrusion process, it can also ensure the uniformity and stability of the bonding layer, thereby improving the overall performance and service life of the cable.

[0047] The production method of the medium voltage power cable also includes: the medium voltage power cable formed by extruding and coating an outer sheath layer 17 on the outside of the metal shielding layer 16 by the cable sheath extruder 33 is subjected to cold zone treatment by a circulating water cooling treatment device 34, and finally rolled up by a winding device 35.

[0048] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the protection scope of the invention.

Claims

1. A medium voltage power cable, characterized in that: include: A conductor, a first semiconductive conductor shielding layer wrapped outside the conductor, an insulating layer wrapped outside the first semiconductive conductor shielding layer, a second semiconductive insulating shielding layer wrapped outside the insulating layer, a semiconductive resistance water tape buffer layer wrapped outside the second semiconductive insulating shielding layer, a metal shielding layer wrapped around the semiconductive resistance water tape buffer layer, and an outer sheath layer wrapped outside the metal shielding layer, wherein the first semiconductive conductor shielding layer, the insulating layer, and the second semiconductive insulating shielding layer are respectively made of polypropylene insulating materials.

2. The medium voltage power cable according to claim 1, characterized in that: The metal shielding layer comprises a single-sided film-coated aluminum tape layer, and the single-sided film-coated aluminum tape layer comprises an aluminum tape and an EAA-PE composite film arranged on the aluminum tape.

3. The medium voltage power cable according to claim 2, characterized in that: The outer sheath layer adopts a polyethylene sheath, and the EAA-PE composite film of the single-sided aluminum tape layer is laminated to the polyethylene sheath.

4. A production device for medium voltage power cables, characterized in that: include: A first wire, a second wire and a connecting wire, wherein the first wire and the second wire are arranged in parallel and at an interval, a flow direction of the first wire is opposite to a flow direction of the second wire, the connecting wire connects the end of the first wire and the initial end of the second wire, and the first wire, the second wire and the connecting wire form a U-shaped wire; The first wire body is provided with a CCV three-layer co-extrusion device and a first cooling device, the CCV three-layer co-extrusion device is used to form a first semi-conductive conductor shielding layer, an insulating layer and a second semi-conductive insulating shielding layer using polypropylene material and wrap them outside the conductor in a three-layer co-extrusion manner to form an insulated wire core, and the first cooling device is used to cool the insulated wire core; The second wire body is provided with a first longitudinal covering device, a second longitudinal covering device and a cable sheath extruder, the first longitudinal covering device is used to longitudinally cover the semiconducting water-resistant tape buffer layer outside the insulating wire core, the second longitudinal covering device is used to cover the metal shielding layer outside the semiconducting water-resistant tape buffer layer, and the cable sheath extruder is used to extrude and cover an outer sheath layer outside the metal shielding layer to form a medium voltage power cable; as well as, The connecting wire body includes a reel, which is used to temporarily store the insulated wire core transmitted from the first wire body and transmit the insulated wire core to the second wire body.

5. The production device for medium voltage power cable according to claim 4, characterized in that: The reel comprises two guide wheels which are spaced apart and arranged horizontally, and a plurality of wire grooves are arranged on the guide wheels.

6. The production device of the medium voltage power cable according to claim 4, characterized in that: The first cooling device comprises a cooling water tank, and the cooling water tank comprises three sections of tank bodies, and the water temperature of each section of the tank body is independently set.

7. A method for producing a medium voltage power cable, characterized in that: The production method is implemented based on the production device of the medium voltage power cable according to any one of claims 4 to 6, and comprises the following steps: Using CCV three-layer co-extrusion equipment to extrude polypropylene material and form a first semi-conductive conductor shielding layer, an insulating layer and a second semi-conductive insulating shielding layer, and wrapping them outside the conductor in a three-layer co-extrusion manner to form an insulated wire core; Using a first cooling device to cool the insulated wire core; The insulated wire core after cooling is passed around the reel and then bent, and then enters the first longitudinal covering device after being bent; Using a first longitudinal covering device to longitudinally cover the semiconductive water-resistant tape buffer layer outside the insulating wire core; The metal shielding layer is covered outside the semiconducting water-resistant tape buffer layer by using a second longitudinal covering device; A cable sheath extruder is used to extrude and coat an outer sheath layer on the metal shielding layer to form a medium voltage power cable.

8. The method for producing a medium voltage power cable according to claim 7, characterized in that: The temperature of the first section of the cooling water tank is set at 65-75°C, and the entire insulated wire core is completely immersed in the water tank; the temperature of the second section of the cooling water tank is set at 50-60°C; the temperature of the third section of the cooling water tank is set at 20-30°C.

9. The method for producing a medium voltage power cable according to claim 7, characterized in that: The semiconducting water-tight tape buffer layer is completely covered on the surface of the insulating wire core by longitudinal coating, and the overlap rate between two adjacent pieces of the semiconducting water-tight tape buffer layer is not less than 10%; and / or, The metal shielding layer is completely covered on the semiconducting water-resistant tape buffer layer by longitudinal covering, the overlapping width of two adjacent metal shielding layers is not less than 5 mm, and the overlapping parts are bonded by high-temperature resistant hot melt adhesive.

10. The method for producing a medium voltage power cable according to claim 7, characterized in that: The metal shielding layer includes a single-sided coated aluminum tape layer, the single-sided coated aluminum tape layer includes an aluminum tape and an EAA-PE composite film arranged on the aluminum tape, the outer sheath layer adopts a polyethylene sheath, and when the polyethylene sheath is extruded by the cable sheath extruder, the high temperature of the polyethylene sheath extrusion process causes the polyethylene sheath to self-bond with the EAA-PE composite film of the single-sided coated aluminum tape layer and form a bonding layer; And / or, the production method of the medium voltage power cable further comprises: water cooling the medium voltage power cable formed by extruding and coating an outer sheath layer on the metal shielding layer using a cable sheath extruder, and finally rolling it up.

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