High-flexibility film-coated stranded wire and stranding forming process

Abstract

The invention relates to a high-flexibility film-coated stranded wire and a stranding forming process, and belongs to the technical field of film-coated stranded wires. A first thin film layer and a second thin film layer are formed outside each film-coated single wire, and the lap joint areas of the two layers are staggered in the circumferential direction; meanwhile, the lap joint areas of the adjacent film-coated single wires in the same stranded layer are further limited to be dispersed and distributed on the cross section, and the probability of concentrated overlapping of lap joint edges is reduced from the source; and the outer twisting layer is bound by matching with the overall winding layer on the outer side, so that the structural form of the twisting layer is more stable under the condition of repeated bending or twisting, and the problems that stress is concentrated due to the fact that a film wrapping lap joint area is easy to concentrate, the lap joint area is easy to wear or displace in the forming process, twisting is loosened, and the outer diameter and the insulation reliability are reduced are solved.

Description

Technical Field

[0001] This invention belongs to the field of membrane-coated stranded wire technology, specifically relating to a highly flexible membrane-coated stranded wire and a stranding forming process. Background Technology

[0002] To meet the power supply or signal transmission requirements of industrial robots, cable chain systems, mobile machine tools, and repeatedly bent motion mechanisms, multiple strands of fine metal conductors are typically twisted together to form conductor bundles. Insulation and binding layers are then applied to the outside of the individual wires or the twisted bundles. To balance small outer diameter with a certain degree of flexibility, a common practice is to spirally overlap and wind each fine conductor with tapes such as polyester film, polyimide film, or fluorinated film to form film-sheathed insulation. Several film-sheathed individual wires are then twisted together in the same or opposite directions, and the outer layer is bound with binding tape, film, or yarn. If necessary, a sheath layer is added to improve wear resistance and dielectric resistance. Compared with thick-walled extruded insulation structures, this type of film-sheathed stranded wire has the characteristics of thinness and high wiring density, and is therefore used in wire harness scenarios where space is limited and a certain degree of bending capability is required.

[0003] However, in highly dynamic application scenarios, such as the servo motor power and feedback hybrid harnesses in the sixth axis of industrial robots or cable chains, the cables are constantly subjected to a combination of small-radius reciprocating bending (the harness needs to repeatedly fold back and forth in a confined space) and torsion (the robotic arm's movements introduce periodic torsion). This is often accompanied by environmental factors such as cable chain friction, oil mist, and coolant. Because existing membrane-wrapped single-wire systems typically use a single overlap or the overlap position is within the same layer, it is prone to "relative concentration." During bending, the sudden change in local thickness at the overlap edge causes micro-bending and stress concentration in the outer conductor. Furthermore, traditional stranding methods often employ a single... In single-compaction, sizing, or constant tension compaction methods, the membrane overlap is subjected to instantaneous radial compression when entering the compaction channel, which can easily lead to membrane wrinkling, shear slippage, and wear at the overlap edge, resulting in local thinning or displacement of the insulation layer. Under repeated torsional loading, relative slippage between strands may cause the strands to loosen and local bulging, ultimately resulting in decreased fatigue life, poor outer diameter stability, and reduced insulation reliability. Therefore, there is a need for a highly flexible membrane stranded wire and its stranding forming process that can reduce stress concentration at the overlap, improve the stability of the stranded structure, and prevent damage to the membrane during the forming process in the above-mentioned high dynamic scenarios. Summary of the Invention

[0004] To address the aforementioned problems in the prior art, this invention provides a highly flexible membrane-sheathed stranded wire and a stranding molding process, which solves the problems of stress concentration caused by easy concentration in the membrane overlap area, as well as the problems of easy wear or displacement of the overlap area during the molding process, which leads to stranding loosening and a decrease in outer diameter and insulation reliability.

[0005] The objective of this invention can be achieved through the following technical solutions: A highly flexible film-coated stranded wire includes a flexible core, an inner stranded layer surrounding the flexible core, and an outer stranded layer located outside the inner stranded layer. Both the inner and outer stranded layers are composed of several film-coated single wires stranded together. Each film-coated single wire includes a metal conductor and a film-coated insulating layer covering the outer periphery of the metal conductor. The film-coated insulating layer includes a first thin film layer and a second thin film layer located outside the first thin film layer. Both the first and second thin film layers extend spirally along the axial direction of the metal conductor and have overlapping areas formed by circumferential overlap. The overlapping areas of the first and second thin film layers are staggered in the circumferential direction. The overlapping areas of adjacent film-coated single wires within the same stranded layer are dispersedly distributed on the cross-section of the stranded wire. An overall winding layer is provided on the outer periphery of the outer stranded layer, and the overall winding layer covers and binds the outer stranded layer.

[0006] As a further aspect of the present invention, the spiral extension direction of the first thin film layer is opposite to the spiral extension direction of the second thin film layer.

[0007] As a further embodiment of the present invention, an interlayer buffer layer is provided between the inner stranded layer and the outer stranded layer. The interlayer buffer layer is a flexible isolation strip or a low-friction film strip that extends spirally along the axial direction. The interlayer buffer layer is located inside the outer stranded layer and is adjacent to the outer periphery of the inner stranded layer.

[0008] As a further embodiment of the present invention, the flexible core is a fiber bundle core or a flexible filling core, wherein the fiber bundle core includes aramid fiber bundles, polyester fiber bundles, or combinations thereof.

[0009] As a further embodiment of the present invention, the overall winding layer includes a first overall film layer and a second overall film layer stacked on top of each other. The first overall film layer and the second overall film layer both extend spirally along the axial direction and their spiral extension directions are opposite. The overlap areas of the first overall film layer and the second overall film layer are staggered in the circumferential direction.

[0010] A stranding process for highly flexible film-coated stranded wire includes the following steps: S1: Material preparation, providing several metal conductor single wires, first film strip and second film strip, and performing wire feeding and tension stabilization on the metal conductor single wires; S2: Single-line film wrapping, with a first thin film layer and a second thin film layer sequentially disposed on the outer periphery of each metal conductor single line, so that the first thin film layer and the second thin film layer form an overlapping area in the circumferential direction, and the overlapping areas of the first thin film layer and the second thin film layer are staggered in the circumferential direction. S3: Stranding and Forming. Several single-wire membrane packages are stranded around a flexible core, and the stranded bundle is sequentially passed through the forming channel along the feeding direction. Within the forming channel, the section from the point where the multiple single-wire membrane packages are just stranded together to the entrance of the flared guide is designated as the gathering and positioning zone; the section from the exit of the flared guide to the entrance of the sizing hole is designated as the sliding and positioning zone; and the section after the wire bundle passes through and leaves the sizing hole is designated as the sizing and locking zone. In the gathering and positioning zone, the single-wire membrane packages are separated... Do not pass through the circumferentially distributed guide holes and enter the trumpet-shaped guide port in a preset circumferential sequence. At the same time, adjust the tension of each membrane-wrapped single wire. In the sliding alignment area, make at least three circumferentially spaced clamping units abut against the outer periphery of the wire harness and apply radial pressure to the wire harness. At the same time, drive the clamping units to rotate around the wire harness axis. In the sizing locking area, make the wire harness pass through the sizing hole. After the wire harness leaves the sizing hole, the adjustable damping torque limiting device applies a damping torque to the wire harness that is opposite to the stranding direction. S4: Overall winding and binding, the overall winding layer is set on the outer periphery of the stranded wire core to bind and fix it; S5: Take-up and Inspection. Take-up the finished product that forms the overall winding layer, and perform outer diameter inspection, insulation withstand voltage inspection, and conductor DC resistance inspection.

[0011] As a further embodiment of the present invention, in the gathering and positioning area of ​​step S3, the circumferentially distributed guide holes are set on the hole guide plate, and each membrane single line passes through different guide holes of the hole guide plate and enters the trumpet-shaped guide opening.

[0012] As a further embodiment of the present invention, in the sliding alignment zone of step S3, the pressing unit is a pressure roller or a pressure shoe, and at least three pressing units are arranged at intervals along the circumference of the wire harness, and rotate around the wire harness axis while applying radial pressure to the wire harness.

[0013] As a further embodiment of the present invention, in the sizing locking zone of step S3, the adjustable damping torque limiting device is disposed on the outlet side of the sizing hole, and the wire harness passes through the adjustable damping torque limiting device after leaving the sizing hole.

[0014] As a further embodiment of the present invention, the adjustable damping torque limiting device includes a guide wheel and a magnetic powder brake, wherein the magnetic powder brake is coaxially connected to the guide wheel, and the wire harness passes around the guide wheel after leaving the sizing hole.

[0015] The beneficial effects of this invention are as follows: This invention employs a combination of circumferentially staggered double-layer film overlap areas at the structural end, dispersed cross-sections of adjacent single-wire overlap areas in the same layer, and overall external winding and binding design. This, along with a continuous forming process involving guide holes at the process end to limit the circumferential sequence of wire entry, tension adjustment, rotational pressing and positioning, and adjustable damping torque control after sizing, prevents the film overlap areas from concentrating on the cross-section, makes it easier to maintain a consistent wire harness outer diameter, and reduces the likelihood of loosening and shape fluctuations in the stranded structure under repeated bending and torsion conditions. Simultaneously, it reduces the risk of wear or displacement of the film sheath during forming and dynamic operating conditions, thereby improving the long-term geometric stability and insulation reliability of the finished cable. Attached Figure Description

[0016] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.

[0017] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the flexible core structure of the present invention; Figure 3 This is a flowchart of the stranding process for the high-flexibility membrane-coated stranded wire of the present invention.

[0018] Explanation of key component symbols: In the diagram: 1. Flexible core; 2. Inner stranded layer; 3. Outer stranded layer. Detailed Implementation

[0019] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided.

[0020] Please see Figure 1 - Figure 3 As shown, this embodiment provides a highly flexible film-coated stranded wire, including a flexible core 1, an inner stranded layer 2 surrounding the flexible core 1, and an outer stranded layer 3 located outside the inner stranded layer 2. Both the inner stranded layer 2 and the outer stranded layer 3 are composed of several film-coated single wires stranded together. Each film-coated single wire includes a metal conductor and a film-coated insulating layer covering the outer periphery of the metal conductor. The film-coated insulating layer includes a first thin film layer and a second thin film layer located outside the first thin film layer. Both the first thin film layer and the second thin film layer extend spirally along the axial direction of the metal conductor and have an overlap area formed by circumferential overlap. The overlap areas of the first thin film layer and the second thin film layer are staggered in the circumferential direction. The overlap areas of adjacent film-coated single wires in the same stranded layer are dispersedly distributed on the cross-section of the stranded wire. An overall winding layer is provided on the outer periphery of the outer stranded layer 3, which covers and binds the outer stranded layer 3.

[0021] It should be noted that the hierarchical structure of flexible core 1, inner stranded layer 2, and outer stranded layer 3 is used here to simultaneously achieve flexibility and structural stability in wiring scenarios that require repeated bending and may involve torsion. Flexible core 1 serves as the flexible support and filling matrix at the center of the wire harness, making it easier to maintain the stability of the cross-sectional shape after stranding and avoiding local collapse or outer diameter fluctuations caused by changes in the central gap. The inner stranded layer 2 and outer stranded layer 3 surrounding flexible core 1 ensure more uniform stress and spatial distribution on the strands, facilitating flexible combination of multiple conductors within a limited outer diameter. Each membrane-insulated single wire uses a metal conductor and a membrane insulation layer to achieve necessary insulation while maintaining thin walls and flexibility. The membrane insulation layer uses a first thin film layer and a second thin film layer stacked together, achieving more stable coverage and insulation through the stacking of multiple thin films. The insulation thickness is redundant; both thin films extend spirally along the axial direction and are provided with circumferential overlap areas, so that the film strip can continuously cover the conductor to form a closed or semi-closed insulation layer; the overlap areas of the first thin film layer and the second thin film layer are staggered in the circumferential direction to avoid the overlap edges of the two layers overlapping at the same circumferential position and forming a local thickness change point; the overlap areas of adjacent film-wrapped single wires in the same stranded layer are distributed in the cross section to avoid the overlap areas of multiple single wires being concentrated and aligned in the cross section, forming a larger range of thickness unevenness or local hard points; finally, an overall winding layer is set on the outer periphery of the outer stranded layer 3 to cover and bind the outer stranded layer 3, providing continuous outer periphery binding and positioning for the outer strands, making it easier to maintain the relative position between the stranded layers, thus cooperating with the staggered and dispersed overlap area structure to improve the overall stability and consistency of the wire harness under dynamic working conditions.

[0022] To address the stress concentration issues caused by the easy concentration of stress in the membrane overlap area, and the problems of wear or displacement of the overlap area during molding, leading to loosening of the strand and a decrease in outer diameter and insulation reliability, this embodiment forms a first thin film layer and a second thin film layer outside each membrane strand, with the overlap areas of the two layers circumferentially offset. Furthermore, the overlap areas of adjacent membrane strands within the same stranded layer are further distributed dispersed across the cross-section, reducing the probability of concentrated overlap edges from the source. Combined with the outer overall winding layer binding the outer stranded layer 3, the structural morphology of the stranded layer is more stable under repeated bending or torsion conditions. This solves the problems of stress concentration caused by the easy concentration of stress in the membrane overlap area, and wear or displacement of the overlap area during molding, leading to loosening of the strand and a decrease in outer diameter and insulation reliability.

[0023] Furthermore, in industrial robot joints, cable carriers, and other applications, cables not only bend repeatedly but also undergo periodic twisting with each movement, and the direction of twisting is not constant. When using a double-layer film sheath, this type of complex motion more easily exposes the relative slippage tendency and overlap stability issues of the double-layer sheath under torsional loads. When the spiral winding directions of the two films are consistent, the relative displacement tendency of the two films in the circumferential direction under torsion is more likely to overlap in the same direction. The overlap edge is more prone to relative movement and local overlap under unidirectional shear conditions, leading to more significant geometric inhomogeneity and the risk of interlayer slippage. In one embodiment, the spiral extension direction of the first film layer is opposite to that of the second film layer. By setting the first and second film layers to opposite spiral directions, the two layers form a mutually restraining relationship in terms of circumferential constraint and shear tendency. The geometric stability of the double-layer sheath is easier to maintain, which helps to prevent the overlapping area from being damaged under dynamic loads, thereby improving the long-term stability of the film sheath insulation layer.

[0024] When a multi-layer structure with an inner stranded layer 2 and an outer stranded layer 3 is set within the same stranded wire, there is a continuous relative micro-motion condition between the outer and inner layers. Even with the single-wire membrane overlap staggered and dispersed, the multi-layer stranded structure may still experience membrane surface wear due to interlayer friction or uncontrolled relative slippage between layers. When the multi-layer stranded structure is bent, the different radii of curvature of the inner and outer layers lead to velocity and displacement differences between them. Simultaneously, torsional loading can cause a relative rotational tendency between the layers. If the inner and outer layers are in direct contact, the membrane surface and overlap edges are more prone to friction under long-term micro-motion conditions. To address wear or localized shearing, in one embodiment, an interlayer buffer layer is provided between the inner stranded layer 2 and the outer stranded layer 3. The interlayer buffer layer is a flexible isolation strip or a low-friction film strip that extends spirally along the axial direction. The interlayer buffer layer is located inside the outer stranded layer 3 and adjacent to the outer periphery of the inner stranded layer 2. Introducing a flexible isolation strip or a low-friction film strip that extends spirally along the axial direction between the inner and outer layers is equivalent to adding a controllable contact interface between the layers, making the interlayer contact state more controllable, reducing the uncertain wear caused by direct hard contact, and improving the repeatability and stability of the multilayer stranded structure under long-term dynamic loads.

[0025] Furthermore, in wiring environments with small bending radii and repeated bending, such as threading inside robot joints and cable chain reversal sections, the geometric stability of the central region of the wire harness significantly affects the consistency of the outer diameter and bending life. Based on the overall structure of the inner and outer stranded layers 3 surrounding the flexible core 1, if the flexible core 1 is not properly selected, problems such as changes in the central gap, unstable cross-sectional shape, and inward collapse or migration of the stranded layers may still occur. Because when the center of the stranded structure is empty or lacks sufficient central support, a radial compression tendency will appear on the bending compression side, making the strands more prone to migration towards the center. After long-term cycling, Changes in the shape of the central void can lead to problems such as non-circular cross-section, fluctuations in outer diameter, and abnormal stress on local strands. In one embodiment, the flexible core 1 is a fiber bundle core or a flexible filler core. The fiber bundle core includes aramid fiber bundles, polyester fiber bundles, or combinations thereof. By using a fiber bundle core or a flexible filler core, and selecting aramid fiber bundles, polyester fiber bundles, or combinations thereof, stable central support and filling can be provided without significantly sacrificing flexibility. This makes it easier for the stranded structure to maintain the consistency of cross-sectional shape and outer diameter under dynamic bending conditions, and also improves the structural stability margin of the entire stranded wire.

[0026] Because single-layer spiral winding is prone to loosening in a certain direction under dynamic torsion conditions, and its overlap area forms a continuous circumferential or axially uneven area on the outer surface; when the wire harness is in long-term contact and friction with the cable chain or surrounding structure, this area is more likely to become a location of concentrated surface stress and wear. To avoid this problem, in one embodiment, the overall winding layer includes a first overall film layer and a second overall film layer that are stacked on each other. The first overall film layer and the second overall film layer both extend spirally along the axial direction and their spiral extension directions are opposite. The overlap areas of the first overall film layer and the second overall film layer are staggered in the circumferential direction. By setting two overall film layers and using opposite winding directions, the outer layer constraint forms a more stable cross constraint geometrically. At the same time, the circumferential staggering of the two overlap areas avoids the formation of a continuous concentrated area on the outer surface by a single overlap area, making the outer surface more uniform and conducive to the stable maintenance of the constraint state of the outer stranded layer 3 under long-term dynamic working conditions.

[0027] A stranding process for highly flexible film-coated stranded wire includes the following steps: S1: Material preparation, providing several metal conductor single wires, first film strip and second film strip, and performing wire feeding and tension stabilization on the metal conductor single wires; S2: Single-line film wrapping, with a first thin film layer and a second thin film layer sequentially disposed on the outer periphery of each metal conductor single line, so that the first thin film layer and the second thin film layer form an overlapping area in the circumferential direction, and the overlapping areas of the first thin film layer and the second thin film layer are staggered in the circumferential direction. S3: Stranding and Forming. Several single-wire membrane packages are stranded around the flexible core 1, and the stranded bundle is sequentially passed through the forming channel along the feeding direction. Within the forming channel, the section from the point where the multiple single-wire membrane packages are just stranded together to the entrance of the flared guide is designated as the gathering and positioning zone; the section from the exit of the flared guide to the entrance of the sizing hole is designated as the sliding and positioning zone; and the section after the wire bundle passes through and leaves the sizing hole is designated as the sizing and locking zone. In the gathering and positioning zone, each single-wire membrane package is... The wires pass through the circumferentially distributed guide holes and enter the trumpet-shaped guide opening in a preset circumferential sequence. At the same time, the tension of each membrane-wrapped single wire is adjusted. In the sliding alignment zone, at least three circumferentially spaced clamping units are brought into contact with the outer periphery of the wire harness and radial pressure is applied to the wire harness. At the same time, the clamping units are driven to rotate around the wire harness axis. In the sizing locking zone, the wire harness passes through the sizing hole. After the wire harness leaves the sizing hole, an adjustable damping torque limiting device applies a damping torque to the wire harness in the opposite direction of the stranding. S4: Overall winding and binding, the overall winding layer is set on the outer periphery of the stranded wire core to bind and fix it; S5: Take-up and Inspection. Take-up the finished product that forms the overall winding layer, and perform outer diameter inspection, insulation withstand voltage inspection, and conductor DC resistance inspection.

[0028] It is worth mentioning that defining the manufacturing process as S1 to S5 and dividing the S3 forming section is to ensure the stable control of the membrane structure formation and stranding in the process. S1, material preparation and tension stabilization of the single wires of the metal conductor, ensures a consistent basic wire supply state when multiple strands enter the forming channel in parallel. S2, single wire membrane wrapping and forming the first and second thin film layers with circumferentially staggered overlap areas, standardizes the membrane wrapping coverage of the single wires before stranding and ensures consistency with the structural requirements of high-flexibility membrane-wrapped stranded wires. S3, stranding, divides the forming channel along the wire bundle's direction of travel into a gathering and positioning area, a sliding and aligning area, and a sizing and locking area. The wire arrangement, process alignment, and final shaping are connected in spatial segments. In the gathering and positioning area, each membrane-wrapped single wire passes through circumferentially distributed guide holes and enters the trumpet-shaped guide opening in a preset circumferential order. At the same time, the tension of each membrane-wrapped single wire is adjusted to fix the wire path and circumferential arrangement of multiple single wires before entering the subsequent forming sections. The tension is consistent; at least three circumferentially spaced clamping units are set in the sliding alignment area to abut against the outer periphery of the wire harness and apply radial pressure. At the same time, the clamping units are driven to rotate around the wire harness axis. Before sizing, the outer periphery of the wire harness is uniformly aligned through multi-point circumferential clamping and rotational motion, which can adapt to different wire diameters and material combinations. In the sizing locking area, the wire harness is passed through the sizing hole, and after the wire harness leaves the sizing hole, an adjustable damping torque limiting device applies a damping torque opposite to the stranding direction. After obtaining the target outer diameter, the torque of the shaping section is adjustable to match the forming needs of different pitches and different specifications of products. S4 Overall winding and binding are set with an overall winding layer on the outer periphery of the wire core to fix the formed stranded structure on the outer periphery for winding and subsequent use. S5 Winding and inspection are carried out to detect the outer diameter, withstand voltage and DC resistance. The geometric dimensions and electrical performance are confirmed in a closed-loop process and factory consistency. The whole process solves the problem that the overlapping area is easy to wear or displacement during the forming process, which causes the stranding to loosen and the outer diameter and insulation reliability to decrease.

[0029] In practice, multiple single wires are affected by factors such as tension differences, jumps, and vibrations during the laying and feeding process. Without fixed hole position constraints, single wires are more likely to cross, change positions, or drift at the entrance, making it difficult to maintain the preset circumferential sequence stably. To address this, in one embodiment, in the gathering and positioning area of ​​step S3, circumferentially distributed guide holes are set on the hole guide plate. Each membrane-covered single wire passes through different guide holes on the hole guide plate and enters the trumpet-shaped guide opening. The hole guide plate provides clear and reproducible wire-passing hole positions, so that each membrane-covered single wire has a relatively fixed feeding path, making it easier to stably implement the steps of the gathering and positioning area in engineering.

[0030] Following the above embodiments, under different combinations of film materials, wire harness outer diameter specifications, and stranding pitches, the steps of applying radial pressure to the sliding alignment zone and rotating around the wire harness axis simultaneously require different contact forms and pressure distribution conditions. If the number of clamping units is too small or their arrangement is uneven, the force on the wire harness in this section may show obvious eccentricity. If the contact form is not clear, the difference in contact state under different materials or wire diameter conditions will make it difficult to uniformly describe the process parameters, thereby affecting the reproducibility of the process steps. In this regard, in one embodiment, in the sliding alignment zone of step S3, the clamping unit is a pressure roller or pressure shoe, and at least three clamping units are arranged at intervals along the circumference of the wire harness and rotate around the wire harness axis while applying radial pressure to the wire harness. Limiting the clamping unit to a pressure roller or pressure shoe is beneficial for selecting appropriate contact forms for different materials and outer diameters in engineering implementation.

[0031] In continuous stranding production, the sizing hole is used to control the outer diameter of the wire harness to the target size, while torque limiting is a subsequent process operation for the wire harness after sizing. To avoid introducing additional torque disturbances before sizing and to ensure a clear sequence of steps, in one embodiment, an adjustable damping torque limiting device is set on the outlet side of the sizing hole in the sizing locking area of ​​step S3. After the wire harness leaves the sizing hole, it passes through the adjustable damping torque limiting device. By arranging the torque limiting device on the outlet side of the sizing hole, the process steps present a clear path of sizing first and then torque constraint in space and sequence, which is also more conducive to maintaining consistency of process steps when switching between different product specifications.

[0032] Furthermore, since torque control devices can be implemented in various ways in engineering, such as friction damping, magnetic powder, and hysteresis, different implementation methods have significant differences in adjustable range, stability, and control method. In this embodiment, the adjustable damping torque limiting device includes a guide wheel and a magnetic powder brake. The magnetic powder brake is coaxially connected to the guide wheel, and the wire harness passes around the guide wheel after leaving the sizing hole.

[0033] Working principle and usage process of this invention: The working principle of this invention lies in simultaneously reducing the concentration of overlapping edges and improving the retention of the stranded structure on both the structural and process links: In the structural link, each membrane-wrapped single wire is covered by a first thin film layer and a second thin film layer, and the overlapping areas of the two layers are circumferentially staggered. At the same time, the overlapping areas of adjacent membrane-wrapped single wires are distributed on the cross section within the same stranded layer, making the spatial distribution of overlapping edges on the cross section more uniform. Then, the overall winding layer covers and binds the outer stranded layer 3, so that the inner and outer stranded layers 3 form a stable interlayer positional relationship around the flexible core 1. In the process link, the guide holes of the gathering positioning area and the preset circumferential sequence establish the incoming arrangement of multiple single wires. The multi-point pressing and rotation around the axis of the sliding positioning area realize the positioning process of the forming process. The sizing holes of the sizing locking area complete the target outer diameter control, and after sizing, an adjustable damping torque limiting device is introduced to control the torque of the wire harness, thereby forming a continuous shaping chain at the end of the forming process that connects with the previous arrangement and positioning.

[0034] During production, the metal conductor single wire is first laid out and tension is stabilized according to S1. Then, according to S2, each single wire is sequentially wrapped with film to form a first thin film layer and a second thin film layer, ensuring that the overlap areas of the two layers are staggered circumferentially. Then, in S3, several film-wrapped single wires are twisted around the flexible core 1 and sequentially passed through the gathering and positioning area, the sliding and positioning area, and the sizing and locking area to complete the arrangement limitation, positioning processing, sizing, and torque control after sizing. Then, according to S4, the overall winding is performed on the outer periphery of the formed wire core to form an overall winding layer and complete the outer periphery binding. Finally, according to S5, the finished product is wound up and the outer diameter, insulation withstand voltage test, and conductor DC resistance test are completed. When the finished product is used in wiring scenarios that require repeated bending or twisting, such as industrial robots, cable chain systems, and mobile machine tools, it can achieve power supply or signal transmission in a small space and maintain good outer diameter consistency and insulation reliability.

[0035] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A highly flexible film-coated stranded wire, characterized in that, The device includes a flexible core, an inner stranded layer surrounding the flexible core, and an outer stranded layer located outside the inner stranded layer. Both the inner and outer stranded layers are composed of several film-coated single wires stranded together. Each film-coated single wire includes a metal conductor and a film-coated insulating layer covering the outer periphery of the metal conductor. The film-coated insulating layer includes a first thin film layer and a second thin film layer located outside the first thin film layer. Both the first and second thin film layers extend spirally along the axial direction of the metal conductor and have overlapping areas formed by circumferential overlap. The overlapping areas of the first and second thin film layers are staggered in the circumferential direction. The overlapping areas of adjacent film-coated single wires within the same stranded layer are dispersedly distributed on the cross-section of the stranded wire. An overall winding layer is provided on the outer periphery of the outer stranded layer, which covers and binds the outer stranded layer.

2. The high-flexibility film-coated stranded wire according to claim 1, characterized in that, The spiral extension direction of the first thin film layer is opposite to that of the spiral extension direction of the second thin film layer.

3. The high-flexibility film-coated stranded wire according to claim 1, characterized in that, An interlayer buffer layer is provided between the inner stranded layer and the outer stranded layer. The interlayer buffer layer is a flexible isolation strip or a low-friction film strip that extends spirally along the axial direction. The interlayer buffer layer is located inside the outer stranded layer and is adjacent to the outer periphery of the inner stranded layer.

4. The high-flexibility film-coated stranded wire according to claim 1, characterized in that, The flexible core is a fiber bundle core or a flexible filling core, and the fiber bundle core includes aramid fiber bundles, polyester fiber bundles, or combinations thereof.

5. The high-flexibility film-coated stranded wire according to claim 1, characterized in that, The overall winding layer includes a first overall film layer and a second overall film layer stacked on top of each other. Both the first overall film layer and the second overall film layer extend spirally along the axial direction and their spiral extension directions are opposite. The overlap areas of the first overall film layer and the second overall film layer are staggered in the circumferential direction.

6. A stranding process for a high-flexibility film-coated stranded wire, based on the high-flexibility film-coated stranded wire according to any one of claims 1-5, characterized in that, Includes the following steps: S1: Material preparation, providing several metal conductor single wires, first film strip and second film strip, and performing wire feeding and tension stabilization on the metal conductor single wires; S2: Single-line film wrapping, with a first thin film layer and a second thin film layer sequentially disposed on the outer periphery of each metal conductor single line, so that the first thin film layer and the second thin film layer form an overlapping area in the circumferential direction, and the overlapping areas of the first thin film layer and the second thin film layer are staggered in the circumferential direction. S3: Stranding and Forming. Several single-wire membrane packages are stranded around a flexible core, and the stranded bundle is sequentially passed through the forming channel along the feeding direction. Within the forming channel, the section from the point where the multiple single-wire membrane packages are just stranded together to the entrance of the flared guide is designated as the gathering and positioning zone; the section from the exit of the flared guide to the entrance of the sizing hole is designated as the sliding and positioning zone; and the section after the wire bundle passes through and leaves the sizing hole is designated as the sizing and locking zone. In the gathering and positioning zone, the single-wire membrane packages are separated... Do not pass through the circumferentially distributed guide holes and enter the trumpet-shaped guide port in a preset circumferential sequence. At the same time, adjust the tension of each membrane-wrapped single wire. In the sliding alignment area, make at least three circumferentially spaced clamping units abut against the outer periphery of the wire harness and apply radial pressure to the wire harness. At the same time, drive the clamping units to rotate around the wire harness axis. In the sizing locking area, make the wire harness pass through the sizing hole. After the wire harness leaves the sizing hole, the adjustable damping torque limiting device applies a damping torque to the wire harness that is opposite to the stranding direction. S4: Overall winding and binding, the overall winding layer is set on the outer periphery of the stranded wire core to bind and fix it; S5: Take-up and Inspection. Take-up the finished product that forms the overall winding layer, and perform outer diameter inspection, insulation withstand voltage inspection, and conductor DC resistance inspection.

7. The high-flexibility film-coated stranded wire and stranding process according to claim 6, characterized in that, In the gathering and positioning area of ​​step S3, the circumferentially distributed guide holes are set on the perforation guide plate, and each membrane single line passes through different guide holes of the perforation guide plate and enters the trumpet-shaped guide opening.

8. The high-flexibility film-coated stranded wire and stranding process according to claim 6, characterized in that, In the sliding alignment zone of step S3, the pressing unit is a pressure roller or a pressure shoe, and at least three pressing units are arranged at intervals along the circumference of the wire harness and rotate around the wire harness axis while applying radial pressure to the wire harness.

9. The high-flexibility film-coated stranded wire and stranding process according to claim 6, characterized in that, In the sizing and locking zone of step S3, the adjustable damping torque limiting device is installed on the outlet side of the sizing hole, and the wire harness passes through the adjustable damping torque limiting device after leaving the sizing hole.

10. The high-flexibility film-coated stranded wire and stranding process according to claim 9, characterized in that, The adjustable damping torque limiting device includes a guide wheel and a magnetic powder brake. The magnetic powder brake is coaxially connected to the guide wheel, and the wire harness passes around the guide wheel after leaving the sizing hole.

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