Cable metal layer, cold-resistant cable and cable preheating method

Abstract

This invention relates to the field of cable manufacturing and discloses a cable metal layer, a cold-resistant cable, and a cable preheating method. The cable metal layer is formed by overlapping and wrapping a first metal strip and a second metal strip. The inner surface of the second metal strip is coated with a second silicone rubber on both sides. Several retractable devices are evenly distributed at the locations coated with the second silicone rubber, and these retractable devices contact the first metal strip when extended. This invention employs a double-layer overlapping wrapping method. Through the special design of the two metal strips, the contact state between the two layers can be adjusted as needed. The contact between the two metal strips forms a loop in a localized area of ​​the cable's metal strip. Heating of the loop through electromagnetic induction or other methods causes localized or overall heating of the cable, reducing the risk of low-temperature stress cracking during cable construction and movement in low-temperature environments. Simultaneously, localized heating allows for segmented heating of necessary areas, reducing energy consumption and heating time.

Description

Technical Field

[0001] This invention relates to the field of cable manufacturing, and in particular to a cable metal layer, a cold-resistant cable, and a cable preheating method. Background Technology

[0002] The outer sheath of power cables is generally made of polyethylene, polyvinyl chloride, or polyolefin materials. These materials have stable performance above -20℃ and can maintain good mechanical and electrical properties. However, when the ambient temperature is below -20℃ or even -30℃, their mechanical properties drop sharply. If the cable is moved or bent, it is easy to cause the sheath to crack under stress. In Northeast and Northwest my country, the outdoor temperature is low in winter. In order to avoid the problem of cable cracking under stress at low temperatures, cable installation and laying are generally not carried out.

[0003] With the development of China's economic construction, the traditional practice of not installing and laying cables in winter is increasingly unable to meet the needs of my country's power construction. It is necessary to carry out the installation, laying, replacement and other work of power cables in the cold winter.

[0004] Therefore, those skilled in the art are dedicated to developing a cable metal layer, a cold-resistant cable, and a cable preheating method that enables the cable to generate its own heat, thus avoiding problems such as cracking and deformation of the sheath material during cable bending and stretching. Summary of the Invention

[0005] In view of the above-mentioned deficiencies of the prior art, the technical problem to be solved by the present invention is to provide a cable metal layer, a cold-resistant cable and a cable preheating method, which enables the cable to generate its own heat and avoids problems such as cracking and deformation of the sheath material during the bending and stretching process of the cable.

[0006] To achieve the above objectives, the present invention provides a cable metal layer, which is formed by overlapping and wrapping a first metal strip and a second metal strip. The inner surface of the second metal strip is coated with a second silicone rubber on both sides. A plurality of retractable devices are evenly distributed along the areas coated with the second silicone rubber. When the retractable devices are extended, they contact the first metal strip. In this cable metal layer, when the retractable devices are retracted, the connection between the first and second metal strips is broken, separating them into a mutually insulated state. When the retractable devices are extended, they are connected, thereby forming a closed circuit, facilitating cable preheating.

[0007] Preferably, the outer surface of the first metal strip is coated with a first silicone rubber on both sides, and a plurality of grooves are evenly distributed in the areas coated with the first silicone rubber. When the retractable device extends, it engages with the grooves. The engagement of the protrusion formed by the extension of the retractable device with the grooves facilitates the connection and disconnection of the first and second metal strips.

[0008] Preferably, the retractable device includes a base with a built-in magnet. The magnet has an extension on its outer edge that fits with the base with a clearance. A first spring is also connected to the magnet, with the other end of the first spring connected to the first metal strip. This arrangement allows the first and second metal strips to be connected via magnetic force.

[0009] Preferably, the retractable device includes an outer groove, within which an inner groove is inverted. A retractable fluid is contained within the space communicating between the outer and inner grooves. A sealing ring is fitted over the inner groove. A second spring is connected to the inner bottom surface of the outer groove, and the other end of the second spring is connected to the inner bottom surface of the inner groove. With this arrangement, the expansion and contraction of the retractable fluid allows the first and second metal strips to connect.

[0010] Preferably, the elastomer comprises, by weight, 60-70 parts water, 30-40 parts ethanol, 0.8-2 parts ethylene glycol, 0.2-1.2 parts nitrite, 0.1-0.8 parts bactericide, and 0.1-0.8 parts defoamer.

[0011] Preferably, the inner surface of the first metal strip is provided with a fleece cloth.

[0012] The present invention also provides a cold-resistant cable, comprising the cable metal layer as described above.

[0013] Preferably, the cable metal layer is provided with an insulation layer, an insulating layer and a conductor in sequence from the inside out; the cable metal layer is provided with a sheath layer from the outside out.

[0014] The present invention also provides a cable preheating method, comprising the following steps:

[0015] S2: Local Preheating: An alternating magnetic field is applied to the cable at the point requiring heating, causing a flowing current to form inside the closed loop of the cable's metal layer, thus generating heat within the metal layer. Local preheating raises the cable temperature, thereby avoiding the risk of low-temperature stress cracking during cable construction and relocation in low-temperature environments.

[0016] Preferably, the following steps are included before step S2:

[0017] S1: Overall preheating: Close the cable metal layer into a ring shape, energize both ends of the cable metal layer to heat up the entire cable, and control the maximum temperature of the inner cable layer to be below 20℃;

[0018] Furthermore, in step S2, when the metal layer heats up to the set temperature, the closed cable metal layer is disconnected, thus releasing the closure.

[0019] The beneficial effects of this invention are as follows: This invention adopts a double-layer metal strip overlapping wrapping method. Through the special design of the two metal strips, the contact state between the two metal strips can be adjusted as needed. The contact between the two metal strips makes the local metal strips of the cable form a loop. The loop is heated by electromagnetic induction and other methods, causing the cable to heat up locally or as a whole, reducing the risk of low-temperature stress cracking during cable construction and movement in low-temperature environments. At the same time, local heating can be used to heat the required sections, reducing the energy consumption and heating time required for heating. Attached Figure Description

[0020] Figure 1 This is a side view of the cable metal layer structure according to Embodiment 1 of the present invention.

[0021] Figure 2 This is a schematic diagram of the inner surface structure of the second metal strip in Embodiment 1 of the present invention.

[0022] Figure 3 This is a schematic diagram of the outer surface structure of the first metal strip in Embodiment 1 of the present invention.

[0023] Figure 4 This is a structural schematic diagram of the retractable device according to Embodiment 1 of the present invention.

[0024] Figure 5 This is a structural schematic diagram of the retractable device in Embodiment 2 of the present invention.

[0025] Figure 6 This is a schematic diagram of the cold-resistant cable in Embodiment 3 of the present invention. Detailed Implementation

[0026] The present invention will be further described below with reference to the accompanying drawings and embodiments. It should be noted that in the description of the present invention, terms such as "upper," "lower," "left," "right," "inner," and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used only for the convenience of describing the present invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific manner. Therefore, they should not be construed as limitations on the present invention. Terms such as "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0027] Example 1

[0028] like Figure 1 As shown, a cable metal layer is formed by overlapping and wrapping a first metal strip 1 and a second metal strip 2. Figure 2As shown, the inner surface of the second metal strip 2 is coated with a second silicone rubber 21 on both sides. Several retractable devices 22 are evenly distributed along the areas coated with the second silicone rubber 21. When extended, the retractable devices 22 contact the first metal strip 1. The outer surface of the second silicone rubber 21 maintains a smooth surface on the metal strip, facilitating heat transfer after the metal strip heats up, while also ensuring the adhesion between the sheath layer and the metal strip. Figure 3 As shown, the outer surface of the first metal strip 1 is coated with first silicone rubber 11 on both sides, and several grooves 12 are evenly distributed at the coated areas. When the telescopic device 22 extends, it engages with the grooves 12. The inner surface of the first metal strip 1 is covered with fleece (not shown), which serves as heat insulation. Silicone rubber is semi-solid at room temperature, has a certain degree of fluidity, and also has a certain degree of viscosity. It mainly serves as insulation and adhesion. Through the arrangement of the first silicone rubber 11 and the second silicone rubber 21, under normal conditions, the first metal strip 1 and the second metal strip 2 are in an isolated and insulated state. When the telescopic device 22 extends, it engages with the grooves 12, making the two come into close contact, thereby connecting the first metal strip 1 and the second metal strip 2, which are normally insulated from each other by the silicone rubber.

[0029] In this embodiment, as Figure 4 As shown, the retractable device 22 includes a base 221, which is a cavity with one end open. A magnet 222 is built into the base 221. The magnet 222 is placed inside the cavity of the base 221 and is not connected. An extension 223 is provided on the outer edge of the magnet 222, which is in clearance fit with the base 221. In this embodiment, the extension 223 is a hollow column. A first spring 224 is also connected to the magnet 222. The first spring 224 is placed in the middle of the extension 223. The other end of the first spring 224 is connected to the first metal strip 1.

[0030] In this embodiment, both the first metal strip 1 and the second metal strip 2 are copper strips. In other embodiments, aluminum strips or other metal strips may also be used. The base 221 and the protruding part 223 are made of the same metal material.

[0031] In this embodiment, a magnetic force is applied to the cable, such as by placing a main magnet externally. The magnet 222 moves towards the first metal strip 1 under the influence of the magnetic force, thereby pushing the protruding member 223 towards the first metal strip 1. The protruding member 223 passes through the silicone rubber and can contact the groove 12, connecting the first metal strip 1 and the second metal strip 2. After the first metal strip 1 and the second metal strip 2 are connected, the metal layer can be heated by the following conductive or self-heating method, thereby preheating the cable. Specific methods are described in other embodiments of this patent specification. When the cable is heated to a predetermined temperature, the main magnet can be removed. The magnet 222 rebounds backward under the elastic force of the first spring 224, the protruding member 223 retracts, and the first metal strip 1 and the second metal strip 2 disconnect, restoring insulation.

[0032] Example 2

[0033] This embodiment is basically the same in structure as Implementation 1, such as... Figure 5 As shown, the difference lies in that the telescopic device 22 includes an outer groove 225, an inner groove 226 is inverted inside the outer groove 225, a telescopic fluid 227 is placed in the space communicating between the outer groove 225 and the inner groove 226, and a sealing ring 228 is fitted over the inner groove 226, so that the telescopic fluid 227 can be sealed in the space communicating between the outer groove 225 and the inner groove 226. A second spring 229 is connected to the bottom surface of the outer groove 225, and the other end of the second spring 229 is connected to the bottom surface of the inner groove 226. When the temperature is below the preset temperature, due to the solidification of the liquid, the expansion volume of the expansion fluid 227 pushes the inner groove 226 towards the first metal strip 1, connecting the first metal strip 1 and the second metal strip 2, which were originally isolated by silicone rubber. When current is passed through the first metal strip 1 and the second metal strip 2, or when current is generated due to changes in the external magnetic field, the first metal strip 1 and the second metal strip 2 will heat up. Some of the heat will be absorbed by the expansion fluid 227. When the liquid temperature rises above the freezing point, the solid will melt into liquid, the volume of the expansion fluid 227 will decrease, and under the elastic force of the second spring 229, the inner groove 226 will contract. The first metal strip 1 and the second metal strip 2 will regain their insulating state. Since the formed circuit is broken, current cannot be formed in the first metal strip 1 and the second metal strip 2, and the heating process is stopped. This setting is not likely to cause problems such as low-temperature brittle fracture of the cable sheath material, nor will it cause excessively high temperatures leading to excessive energy consumption. The heating stop temperature can also be flexibly set by adjusting the liquid formula, and the liquid has a large specific heat capacity, which can better reflect the overall temperature of the cable's outer surface.

[0034] The components of 226 stretching fluid, by weight, include 60-70 parts water, 30-40 parts ethanol, 0.8-2 parts ethylene glycol, 0.2-1.2 parts nitrite, 0.1-0.8 parts bactericide, and 0.1-0.8 parts defoamer. Different freezing points can be set by adjusting the formula ratios.

[0035] The applicant determined the following formulations with different freezing points through experiments, as shown in Table 1:

[0036] Table 1: Formulation Table of Expansion Liquids with Different Freezing Points

[0037]

[0038] Of course, the formulation of the stretching fluid can be adjusted within the scope of this invention according to actual needs.

[0039] Example 3

[0040] A cold-resistant cable includes a cable metal layer as described in Embodiment 1 or Embodiment 2 above.

[0041] like Figure 6As shown, the cable metal layer is provided with an isolation and heat preservation layer 3, an insulation layer 4 and a conductor 5 in sequence, and the cable metal layer is provided with a sheath layer 6 in sequence.

[0042] In this invention, the insulation layer 3 is made of a tape with a certain elasticity and strong heat insulation capacity, which avoids direct contact between the cable metal layer and the insulation layer 4, which could easily cause the insulation layer 4 to be scratched by the edge of the cable metal layer. At the same time, it can block the heat emitted by the cable metal layer from being transferred to the core of the insulation layer 4, allowing more heat to be transferred to the cable sheath layer 6. Specifically, it can be made of pearl cotton or foam material.

[0043] In addition to serving as a shielding and protective layer, the cable metal layer also acts as a heat source for the cable. The outer surface of the second metal strip 2 is a smooth copper / aluminum strip or similar material, which facilitates heat transfer after the copper strip heats up. At the same time, it ensures the adhesion between the outer sheath and the metal strip. The cable sheath layer 6 is formed by extrusion of polyethylene, polyvinyl chloride, or polyolefin materials.

[0044] Example 4

[0045] A cable preheating method, employing a cable metal layer as described in Example 1 or Example 2, or a cold-resistant cable as described in Example 3, specifically includes the following steps:

[0046] S1: Overall Preheating: The cable's metal layer is closed into a ring shape. Electricity is applied to both ends of the cable's metal layer, causing the entire cable to heat up, while controlling the maximum temperature of the inner cable layer to remain below 20°C. If the cable metal layer of Example 1 is used, magnetic force is applied to connect the first metal strip 1 and the second metal strip 2, forming a closed loop. For Example 2, at a lower temperature, the first metal strip 1 and the second metal strip 2 expand due to the solidification of the expansion fluid, connecting and forming a closed loop; details will not be elaborated here.

[0047] During the overall preheating stage, electrodes are connected to both ends of the cable's metal layer, and a low-voltage current is applied. The cable begins to heat up as a whole. This stage is called overall preheating. Since cables are generally coiled on a reel, the outer cable dissipates heat quickly, while the inner cable does not dissipate heat easily. Prolonged preheating can lead to an excessive temperature difference between the inner and outer cables, affecting cable quality and wasting energy. Therefore, in this invention, during the overall preheating stage, the maximum temperature of the inner cable is controlled to be below 20°C.

[0048] S2: Localized preheating: An alternating magnetic field is applied to the cable at the point requiring heating, causing a current to flow inside the closed loop of the cable's metal layer, thus generating heat in the metal layer. When the self-heating of the metal layer reaches the set temperature, the closed cable metal layer is disconnected, releasing the closure.

[0049] After overall preheating, some parts of the cable (such as the outer layer) may still not reach the predetermined temperature. Therefore, local preheating of the cable is required. By closing the cable metal layer as described in Examples 1 and 2, and then applying a Helmholtz coil to the heated part of the cable, an alternating magnetic field can be formed, thereby causing the cable metal layer to self-heat and achieve the purpose of cold resistance.

[0050] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A cable metal layer characterized by comprising The first metal band (1) and the second metal band (2) are wrapped together, the inner surface of the second metal band (2) is coated with the second silicone rubber (21), and a plurality of retractable devices (22) are uniformly distributed at the coating position of the second silicone rubber (21), the retractable devices (22) are in contact with the first metal band (1) when they are extended; When the retractable devices (22) are retracted, the connection between the first metal band (1) and the second metal band (2) can be disconnected, so that the two are separated and in an insulated state, and when the retractable devices are extended, the two are connected, so that a closed loop can be formed, which is convenient for preheating the cable.

2. The cable metal layer of claim 1, wherein: The outer surface of the first metal band (1) is coated with the first silicone rubber (11), and a plurality of grooves (12) are uniformly distributed at the coating position of the first silicone rubber (11); the retractable devices (22) are matched with the grooves (12) when they are extended.

3. The cable metal layer of claim 1, wherein: The retractable device (22) comprises a base (221), a magnet (222) is built in the base (221), the outer edge of the magnet (222) is provided with an extension piece (223) which is matched with the base (221) with a gap, a first spring (224) is further connected to the magnet (222), and the other end of the first spring (224) is connected to the first metal band (1).

4. The cable metal layer of claim 1, wherein: The retractable device (22) comprises an outer groove (225), an inner groove (226) is invertedly buckled in the outer groove (225), a retractable liquid (227) is built in the space communicated between the outer groove (225) and the inner groove (226), a sealing ring (228) is sleeved on the outer surface of the inner groove (226), a second spring (229) is connected to the inner bottom surface of the outer groove (225), and the other end of the second spring (229) is connected to the inner bottom surface of the inner groove (226).

5. The cable metal layer of claim 4, wherein: The composition of the retractable liquid (227) comprises, by mass, 60-70 parts of water, 30-40 parts of ethanol, 0.8-2 parts of ethylene glycol, 0.2-1.2 parts of nitrite, 0.1-0.8 parts of bactericide, and 0.1-0.8 parts of defoaming agent.

6. The cable metal layer of claim 1, wherein: The inner surface of the first metal band (1) is provided with flannelette.

7. A cold-resistant cable, characterized by: The cable metal layer comprises the cable metal layer as claimed in any one of claims 1 to 6.

8. The cold-resistant cable of claim 7, wherein: The cable metal layer is sequentially provided, inward, with an insulation and heat preservation layer (3), an insulation layer (4), and a conductor (5), and is provided, outward, with a sheath layer (6).

9. A method of preheating a cable, characterized by, The cable metal layer as claimed in any one of claims 1 to 6 comprises the following steps: S2: Partial preheating: an alternating magnetic field is applied to the cable to be heated, so that a flowing current is formed in the closed cable metal layer, thereby causing the cable metal layer to generate heat spontaneously.

10. The cable preheating method of claim 9, wherein the step of applying a voltage to the cable is performed after the step of applying a current to the cable. The step S2 further comprises the following step: S1: Overall preheating: the cable metal layer is closed into a ring, and both ends of the cable metal layer are electrified, so that the whole cable generates heat, and the highest temperature of the inner cable is controlled to be lower than 20℃; In the step S2, when the metal layer generates heat spontaneously to reach a set temperature, the closed cable metal layer is disconnected, and the closure is released.

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