Waterproof flexible cable and preparation method thereof

Abstract

The invention discloses a waterproof flexible cable and a preparation method thereof. The cable comprises a cable core, and the periphery of the cable core is coated with an outer sheath; the cable core comprises a filling frame and a plurality of insulated wire cores, the plurality of insulated wire cores are distributed along the circumference and stranded, and the filling frame is distributed in a central area among the plurality of insulated wire cores in a filling manner and is in contact with each insulated wire core. Compared with the prior art, the waterproof flexible cable provided by the invention has excellent waterproof performance, relatively good bending performance and electrical stability.

Description

Technical Field

[0001] This invention relates to power cords, and more specifically to a waterproof flexible cable and its preparation method. Background Technology

[0002] I. Waterproofing Challenges and Common Technologies for Traditional Cables For a long time, the reliable operation of power cables in humid, water-immersed environments (such as underground pipe networks, tunnels, mines, ships, and long-term outdoor operation) has been a major challenge. Once moisture enters the cable, it can trigger a series of fatal problems: 1. Insulation aging and breakdown: Moisture under the influence of an electric field will produce "water trees", which will gradually evolve into "electric trees", eventually leading to the breakdown of the insulation layer.

[0003] 2. Conductor corrosion: Moisture reacts with copper conductors to form copper oxide, copper carbonate, etc., which leads to a reduction in conductor cross-section, an increase in resistance, local overheating, and even wire breakage.

[0004] 3. System short circuit: In multi-core cables, moisture may cause phase-to-phase short circuits or grounding faults.

[0005] To address these challenges, the industry has developed a variety of traditional waterproofing technologies, but each has its limitations: Metal sheaths (such as aluminum-plastic composite tape): While they can provide a good radial waterproof barrier, they are not flexible, heavy, and expensive, making them unsuitable for flexible cables that require frequent movement or bending.

[0006] Plain filler: Thick layers of petroleum jelly or plain paste-like compounds are filled between the cable cores. This results in a significant increase in cable weight and diameter, loss of flexibility, difficulty in splicing and termination, and some fillers may be incompatible with the insulation material.

[0007] Water-blocking tape: A water-blocking tape that expands when exposed to water is wrapped around the cable core. This adds a process step, and for flexible cables, repeated bending can easily cause the tape to loosen or create gaps, forming water-permeable channels.

[0008] II. Shortcomings of existing technologies and the core problems to be solved by this solution The aforementioned traditional technologies mainly focus on waterproofing the "outside of the cable core" or "between the cable cores," and they share a common drawback: they cannot effectively prevent moisture from penetrating and spreading along the longitudinal (axial) direction of the cable.

[0009] Specifically, this manifests as follows: 1. "Capillary effect" inside the conductor: There are a large number of micro gaps inside stranded conductors. Once water enters the cable end or is partially damaged, the water will migrate long distances inside the conductor like through capillaries, corroding the entire conductor and making it difficult to locate the fault point.

[0010] 2. "Edge penetration" at the insulation interface: Moisture can flow longitudinally along the tiny gaps between the insulation layer and the conductor. Traditional non-bonded insulation structures cannot prevent this path.

[0011] 3. "Fast Track" in Cable Core Gaps: Even with center filling, the gaps between the cores in the traditional structure are still a fast track for the longitudinal diffusion of moisture, and ordinary filling sacrifices flexibility.

[0012] 4. "Hidden spread" under the sheath: If the sheath and the cable core are not tightly bonded, once moisture penetrates under the sheath, it will spread laterally in the gap between the sheath and the cable core, affecting a large area.

[0013] In summary, the core problem of the background technology is the lack of a comprehensive solution that can simultaneously achieve efficient longitudinal waterproofing, maintain cable flexibility, and facilitate manufacturing. Summary of the Invention

[0014] In order to solve the above problems, the present invention provides a waterproof flexible cable and a method for its preparation.

[0015] To achieve the above objectives, the technical solution of the present invention is as follows: A waterproof flexible cable and its manufacturing method are disclosed. The cable includes a cable core, and the cable core is covered with an outer sheath. The cable core includes a filler frame and a plurality of insulated wire cores. The plurality of insulated wire cores are distributed circumferentially and twisted together. The filler frame fills the central area between the plurality of insulated wire cores and contacts each insulated wire core.

[0016] In a preferred embodiment of the present invention, the filling frame is a water-blocking yarn, which is in contact with the insulating wire core.

[0017] In a preferred embodiment of the present invention, the insulated core includes a waterproof conductor, and the waterproof conductor is covered from the inside out with a waterproof adhesive layer, an insulation layer, and a water-blocking layer.

[0018] In a preferred embodiment of the present invention, the waterproof conductor includes a flexible conductor and a waterproof adhesive, wherein the waterproof adhesive fills the space between the individual wires of the flexible conductor.

[0019] In a preferred embodiment of the present invention, the outer sheath is formed by tightly extruding sheath material onto the cable core.

[0020] A method for preparing a waterproof flexible cable, comprising: Step 1: Preparation of waterproof conductor, the production process includes: Step 1: Conductor stranding. Multiple thin, soft copper wires are stranded or regularly twisted together to form a soft conductor that meets the requirements.

[0021] Step 2: Fill the conductor with waterproof adhesive using the "online pressure injection method". A dedicated filling head and precision metering pump are installed at the stranding die of the stranding machine. The waterproof adhesive, preheated to the appropriate temperature, is injected precisely and continuously into the gaps inside the stranded conductor, synchronized with the stranding speed, ensuring uniform and sufficient filling without contaminating the conductor surface.

[0022] Step 2: Preparation of insulated wire cores, the production process of which includes: Step 3: Conductor preheating and cleaning. Preheat the conductor filled with waterproof adhesive and clean the surface to ensure there is no oil.

[0023] Step 4: Hot melt adhesive coating. Using the "extrusion coating method" or "crosshead die coating method", a hot melt adhesive extruder is added before the insulation extruder. The conductor first passes through a special coating die and is evenly coated with a layer of molten hot melt adhesive.

[0024] Step 5: Insulation extrusion and bonding. Using "tandem extrusion" or "co-extrusion", the conductor coated with hot melt adhesive immediately (before the hot melt adhesive has cured) enters the insulation extruder head. The insulating material combines with the hot melt adhesive in a high-temperature molten state. After cooling, a three-in-one bonding structure of "conductor-hot melt adhesive-insulation layer" is formed, achieving radial waterproofing and interface sealing.

[0025] Step 6: Spray water-blocking powder onto the insulating surface using either electrostatic spraying or powder cloud / fluidized bed methods. After the insulated wire core has cooled and set but before winding, it is passed through a sealed spraying chamber. Utilizing the electrostatic field or the principle of airflow boiling, the dry water-blocking powder is evenly and quantitatively adsorbed onto the surface of the insulated wire core. The powder thickness and adhesion are controlled, and the winding process must be gentle to prevent excessive powder shedding.

[0026] Step 3: Preparing the cable core, the production process includes: Step 7: Wire laying and guide wheel processing. Lay out multiple insulated wire cores that have been coated with water-blocking powder. All guide wheels and wire passing devices must be made of low-friction materials (such as ceramic) and kept clean to protect the powder layer.

[0027] Step 8: Fill the center with water-blocking yarn. During cabling, place the water-blocking yarn as the center filling element in the center of the cable core.

[0028] Step 9: Stranding into a cable. Using a cable-forming machine, several insulated wire cores are stranded together with the central water-blocking yarn at a certain pitch to form a round and compact cable core. The stranding tension and pitch are optimized to minimize scratching and damage to the water-blocking powder layer on the insulation surface while ensuring a compact structure.

[0029] Step 4: Prepare the finished cable. The production process includes: Step 10: Sheath extrusion. The cable core is extruded using an extrusion die. After preheating, the cable core passes through the extrusion die. This die features a long sheath bearing area, which exerts significant pressure on the cable core, allowing the molten sheath material to tightly embed and fill all gaps in the cable core, forming a solid whole.

[0030] Step 11: Cooling and winding. After the sheath is fully cooled in the cooling water tank, it is pulled by the track traction machine and finally wound up by the take-up reel.

[0031] The beneficial effects of this invention are: The waterproof flexible cable provided by this invention has excellent waterproof performance, good bending performance and electrical stability compared with the prior art. Attached Figure Description

[0032] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0033] Figure 1 This is a schematic diagram of the structure of the waterproof flexible cable provided by the present invention. Detailed Implementation

[0034] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below with reference to specific illustrations.

[0035] See Figure 1 The diagram shows an example of the internal structure of the waterproof flexible cable provided by the present invention.

[0036] As shown in the figure, this waterproof flexible cable mainly consists of a cable core 300, which is surrounded by an outer sheath 400. The cable core 300 includes a filler frame 200 and several insulated wire cores 100. The several insulated wire cores 100 are distributed and twisted together along the circumference. The filler frame 200 fills the central area between the several insulated wire cores 100 and contacts each insulated wire core 100.

[0037] The insulated core 100 can be of the same specification or different specifications.

[0038] Thus, several insulated wire cores 100 are distributed and twisted together along the same circumference, while the filling frame 200 is set in the central area between the several insulated wire cores 100 and contacts each insulated wire core 100 respectively, thereby forming a corresponding cable core 300.

[0039] The filling frame 200 is made of water-blocking yarn, which preferably uses super absorbent fiber yarn. The super absorbent fiber yarn is made of fibers directly spun from super absorbent polymer (SAP). When it comes into contact with water, the fibers in the entire yarn expand as a whole. The expansion speed is fast and the expansion ratio is high. It does not contain chemical adhesives and is cleaner. It can provide the fastest and most thorough expansion and water blocking effect. In addition, the super absorbent fiber yarn has a stable structure, is not easy to hydrolyze and age, and has good softness.

[0040] Furthermore, the filler frame 200 is made of super absorbent fiber yarn, which makes the cable core 300 more flexible, which can reduce the force between the insulated cores 100. In addition, it can fix the position of the insulated cores 100, and will not loosen even if the cable core 300 is not tied with a protective tape, and the structure will remain stable.

[0041] The insulated core 100 includes a waterproof conductor 110, and the waterproof conductor 110 is covered from the inside out with a waterproof adhesive layer 120, an insulation layer 130, and a water-blocking layer 140.

[0042] The waterproof conductor 110 includes a flexible conductor 111 and a waterproof adhesive 112, wherein the waterproof adhesive 112 fills the spaces between the individual wires of the flexible conductor 111.

[0043] Furthermore, the material of the soft conductor 111 is specifically one of copper, tin-plated copper, aluminum, or aluminum alloy. The waterproof adhesive 112 is conventionally made of synthetic hydrocarbon oil-based water-blocking paste. Synthetic hydrocarbon oil-based water-blocking paste has better performance than mineral oil, more stable viscosity-temperature characteristics, and better low-temperature performance. When the cable needs to withstand high and low temperatures, the waterproof adhesive 112 uses silicone oil-based water-blocking paste. Silicone oil-based water-blocking paste has excellent high and low temperature resistance (wide operating temperature range), extremely stable chemical properties, does not corrode metals, and has excellent compatibility with almost all insulating materials (XLPE, EPR, PVC, etc.) without causing them to swell or deteriorate in performance.

[0044] The waterproof adhesive layer 120 uses one of the following: ethylene-vinyl acetate (EVA) type hot melt adhesive, polyamide (PA) type hot melt adhesive, or polyurethane (PU) type hot melt adhesive.

[0045] The water-blocking layer 140 is formed by coating water-blocking powder onto the surface of the insulating layer 130. Specifically, the water-blocking powder is one of the following: acrylate water-blocking powder, starch-acrylic acid graft copolymer water-blocking powder, or polyvinyl alcohol water-blocking powder.

[0046] The outer sheath 400 is formed by tightly wrapping and extruding sheath material onto the cable core 300.

[0047] The cable constructed using the above technical solutions shows that the waterproof adhesive layer 120, insulation layer 130, and outer sheath 400 form a radial sealing structure, thus giving the cable good radial waterproofing performance. The waterproof adhesive 112, waterproof adhesive layer 120, water-blocking layer 140, and filler frame 200 are all water-blocking materials. The waterproof adhesive 112 fills the space between individual wires in the conductor, the waterproof adhesive layer 120 fills the space between the conductor and the insulation and bonds it without gaps, the filler frame 200 fills the central area where the insulated cores are in contact with each other, and the water-blocking layer 140 is located between the outer surface of the filler frame 200, which is in contact with the outer surface of the insulated core 100, and the inner surface of the outer sheath 400. This gives the cable good longitudinal water-blocking performance, resulting in excellent waterproofing performance.

[0048] In addition, the cable's unfilled, compact structure makes the stress distribution more uniform when the cable is bent, resulting in better bending fatigue resistance. The tight core structure reduces internal air gaps, which partially improves the cable's capacitance, inductance, and other distributed parameters, making its electrical performance more stable.

[0049] A method for preparing a waterproof flexible cable, comprising: Step 1: Preparation of waterproof conductor, the production process includes: Step 1: Conductor stranding. Multiple thin, soft copper wires are stranded or regularly twisted together to form a soft conductor that meets the requirements.

[0050] Step 2: Fill the conductor with waterproof adhesive using the "online pressure injection method". A dedicated filling head and precision metering pump are installed at the stranding die of the stranding machine. The waterproof adhesive, preheated to the appropriate temperature, is injected precisely and continuously into the gaps inside the stranded conductor, synchronized with the stranding speed, ensuring uniform and sufficient filling without contaminating the conductor surface.

[0051] Step 2: Preparation of insulated wire cores, the production process of which includes: Step 3: Conductor preheating and cleaning. Preheat the conductor filled with waterproof adhesive and clean the surface to ensure there is no oil.

[0052] Step 4: Hot melt adhesive coating. Using the "extrusion coating method" or "crosshead die coating method", a hot melt adhesive extruder is added before the insulation extruder. The conductor first passes through a special coating die and is evenly coated with a layer of molten hot melt adhesive.

[0053] Step 5: Insulation extrusion and bonding. Using "tandem extrusion" or "co-extrusion", the conductor coated with hot melt adhesive immediately (before the hot melt adhesive has cured) enters the insulation extruder head. The insulating material combines with the hot melt adhesive in a high-temperature molten state. After cooling, a three-in-one bonding structure of "conductor-hot melt adhesive-insulation layer" is formed, achieving radial waterproofing and interface sealing.

[0054] Step 6: Spray water-blocking powder onto the insulating surface using either electrostatic spraying or powder cloud / fluidized bed methods. After the insulated wire core has cooled and set but before winding, it is passed through a sealed spraying chamber. Utilizing the electrostatic field or the principle of airflow boiling, the dry water-blocking powder is evenly and quantitatively adsorbed onto the surface of the insulated wire core. The powder thickness and adhesion are controlled, and the winding process must be gentle to prevent excessive powder shedding.

[0055] Step 3: Preparing the cable core, the production process includes: Step 7: Wire laying and guide wheel processing. Lay out multiple insulated wire cores that have been coated with water-blocking powder. All guide wheels and wire passing devices must be made of low-friction materials (such as ceramic) and kept clean to protect the powder layer.

[0056] Step 8: Fill the center with water-blocking yarn. During cabling, place the water-blocking yarn as the center filling element in the center of the cable core.

[0057] Step 9: Stranding into a cable. Using a cable-forming machine, several insulated wire cores are stranded together with the central water-blocking yarn at a certain pitch to form a round and compact cable core. The stranding tension and pitch are optimized to minimize scratching and damage to the water-blocking powder layer on the insulation surface while ensuring a compact structure.

[0058] Step 4: Prepare the finished cable. The production process includes: Step 10: Sheath extrusion. The cable core is extruded using an extrusion die. After preheating, the cable core passes through the extrusion die. This die features a long sheath bearing area, which exerts significant pressure on the cable core, allowing the molten sheath material to tightly embed and fill all gaps in the cable core, forming a solid whole.

[0059] Step 11: Cooling and winding. After the sheath is fully cooled in the cooling water tank, it is pulled by the track traction machine and finally wound up by the take-up reel.

[0060] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A waterproof flexible cable, characterized by, The cable comprises a cable core, and the cable core is peripherally covered with an outer sheath; the cable core comprises a filler frame and a plurality of insulated wire cores, the plurality of insulated wire cores are distributed and twisted along the circumference between each other, and the filler frame fills the central area distributed between the plurality of insulated wire cores and is in contact with each insulated wire core respectively.

2. The waterproof flexible electrical cable according to claim 1, characterized in that, The filler frame is water-blocking yarn, and the water-blocking yarn is in contact with the insulated wire core.

3. The waterproof flexible electrical cable of claim 1, wherein, The insulated wire core comprises a waterproof conductor, and the waterproof conductor is peripherally covered with a waterproof adhesive layer, an insulation layer and a water-blocking layer in sequence from inside to outside.

4. The waterproof flexible electrical cable according to claim 3, characterized in that, The waterproof conductor comprises a soft conductor and waterproof glue, and the waterproof glue is filled into the single wire of the soft conductor.

5. The waterproof flexible electrical cable of claim 1, wherein, The outer sheath is tightly extruded on the cable core by a sheath material.

6. A preparation method of a waterproof flexible cable, comprising: Step one: preparing a waterproof conductor, and the production process comprises: Step 1: conductor twisting, a plurality of thin soft copper wires are twisted by bundle twisting or normal twisting to form a required soft conductor; Step 2: filling waterproof glue in the conductor, and an "on-line pressure injection method" is adopted; at the doubling die of the twisting machine, a special filling head and a precision metering pump are installed, the waterproof glue preheated to a suitable temperature is injected into the gap in the conductor inside through the metering pump and the twisting speed synchronously, so that the filling amount is accurate and continuous, and the conductor surface is not polluted by overfilling; Step two: preparing an insulated wire core, and the production process comprises: Step 3: conductor preheating and cleaning, the conductor filled with waterproof glue is preheated and cleaned to ensure that there is no oil stain on the surface; Step 4: hot melt adhesive coating, an "extrusion coating method" or a "cross head die coating method" is adopted, a hot melt adhesive extruder is added before the insulation extruder, and the conductor is uniformly wrapped with a layer of molten hot melt adhesive through a special coating die; Step 5: insulation extrusion and bonding, a "tandem extrusion" or "co-extrusion" is adopted, the conductor coated with hot melt adhesive immediately enters the insulation extruder head (before the hot melt adhesive is solidified), and the insulation material is combined with the hot melt adhesive in a high-temperature molten state to form a "conductor-hot melt adhesive-insulation layer" three-in-one bonding structure after cooling, so that radial waterproofing and interface sealing are realized; Step 6: spraying water-blocking powder on the surface of the insulation, an "electrostatic spraying method" or a "powder cloud / fluidized bed method" is adopted, the insulation wire core passes through a closed spraying cabin after cooling and setting and before winding, and dry water-blocking powder is uniformly and quantitatively adsorbed on the surface of the insulation wire core by using an electrostatic field or gas flow boiling principle to control the powder thickness and adhesion, and the powder is prevented from falling off in large quantities during winding by gentle winding; Step three: preparing a cable core, and the production process comprises: Step 7: wire laying and guide roller treatment, a plurality of insulated wire cores coated with water-blocking powder are laid, and all guide rollers and wire passing devices must be made of low-friction materials (such as ceramics) and kept clean to protect the powder layer; Step 8: filling water-blocking yarn in the center, the water-blocking yarn is placed in the center of the cable core as a central filling element during cabling. Step 9: Stranding into cable, several insulated cores are stranded into round and compact cable core with certain pitch by cable stranding machine, and the stranding tension and pitch are optimized to minimize the scratch and damage to the water-proof powder layer on the insulation surface while ensuring compact structure; Step four: Preparation of finished cable, the production process includes: Step 10: Sheath extrusion, extrusion is carried out by "extrusion die", the cable core is preheated and then passes through the extrusion die. The die has the characteristics that the wire bearing area of the die sleeve is long, and a larger pressure is generated on the cable core, so that the molten sheath material can tightly embed and fill all the gaps of the cable core, and combine with the cable core into a solid whole; Step 11: Cooling and winding, after the sheath is fully cooled in the cooling water tank, it is pulled by a caterpillar traction machine and finally wound by a take-up reel.

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