Winding-resistant drag chain cable for robot

Abstract

The invention belongs to the technical field of cables, and particularly relates to a bending-resistant tow chain cable for a robot, which comprises a conductor core layer, an insulating layer, an inner sheath layer, a braid layer, a non-woven fabric layer and an outer sheath layer, the insulating layer wraps the conductor core layer, the inner sheath layer is positioned outside the insulating layer, the braid layer covers the inner sheath layer, the non-woven fabric layer is positioned outside the inner sheath layer, and the non-woven fabric layer is positioned outside the outer sheath layer. The non-woven fabric layer is wound on the braid layer, the outer sheath layer wraps the non-woven fabric layer, the conductor core layer is formed by twisting a plurality of flexible tinned copper wires and aramid fibers, and the surfaces of the flexible tinned copper wires are coated with carbon nanotube coatings; according to the invention, the thickness of the carbon nanotube coating is controlled to be 3-5 [mu] m, and the carbon nanotube coating is prepared by adopting a coating process, has excellent conductivity and mechanical strength, can effectively reduce the contact resistance change of the flexible tinned copper wire in the repeated winding process, and enhances the wear resistance and corrosion resistance of the surface of the copper wire, thereby prolonging the service life of the conductor core layer.

Description

Technical Field

[0001] This invention belongs to the field of cable technology, specifically a flex-resistant drag chain cable for robots. Background Technology

[0002] Drag chain cables are widely used in CNC machine tools, automated machinery, and robots as protective devices for wires and cables. In the prior art, patent CN103854735B discloses a drag chain cable comprising a conductor core layer, an insulation layer, an inner sheath layer, a braided layer, a non-woven fabric layer, and an outer sheath layer. Its structure improves resistance to deformation and shielding performance. For example, the conductor core layer of this patent uses multiple flexible tin-plated copper wires twisted with aramid fiber, the insulation layer is a semi-rigid thermoplastic elastomer, and the non-woven fabric layer alleviates stress on the braided layer.

[0003] However, with the development of robotics technology, cables need to operate at smaller bending radii (e.g., 5 times the diameter), higher moving speeds (over 5 m / s), and longer strokes. Existing cables still have the following problems: insufficient bending life (conductor breakage is easy under frequent bending), limited shielding effectiveness (unable to meet high-frequency electromagnetic interference protection), heavy weight affecting robot energy efficiency, and lack of intelligent monitoring functions. Therefore, there is an urgent need for a bending-resistant drag chain cable specifically designed for robots, with structural innovation.

[0004] While the existing patented technologies have structural advantages, they are not optimized for high-frequency bending scenarios in robots. For example, the conductor materials experience rapid fatigue and high interlayer friction, and they lack lightweight and intelligent elements, making it difficult to meet the comprehensive performance requirements of modern industrial robots for cables under extreme dynamic conditions. This invention addresses these technical pain points by employing multi-dimensional innovative designs for the conductor core layer, insulation layer, protective structure, and functional integration. It aims to significantly improve the bending fatigue resistance, electromagnetic compatibility, lightweight level, and intelligent monitoring capabilities of drag chain cables, thereby meeting the stable operation requirements of robots in high-speed, high-frequency, and long-stroke motion scenarios. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, this invention proposes a flexural drag chain cable for robots. This invention primarily addresses the problem that existing drag chain cables, under high-frequency, small-radius bending conditions in robots, are prone to conductor fatigue fracture due to repeated bending, leading to a shortened cable lifespan.

[0006] The technical solution adopted by the present invention to solve its technical problem is as follows: The present invention provides a flex-resistant drag chain cable for robots, comprising a conductor core layer, an insulation layer, an inner sheath layer, a braided layer, a non-woven fabric layer, and an outer sheath layer. The insulation layer wraps around the conductor core layer, the inner sheath layer is located outside the insulation layer, the braided layer covers the inner sheath layer, the non-woven fabric layer is wound around the braided layer, and the outer sheath layer wraps around the non-woven fabric layer. The conductor core is made of multiple flexible tin-plated copper wires twisted together with aramid fibers, and the surface of the flexible tin-plated copper wires is coated with a carbon nanotube coating. The diameter of a single flexible tin-plated copper wire is between 0.05 mm and 0.15 mm, and the diameter tolerance does not exceed 0.01 mm.

[0007] The coating process for carbon nanotube coatings is as follows: Step 1: First, add the carbon nanotube powder to a 5% (w / w) polyvinylpyrrolidone ethanol solution and ultrasonically disperse for 30 minutes to form a 0.8% carbon nanotube dispersion. Step 2: The annealed flexible tin-plated copper wire is then passed through the dispersion bath at a speed of 1.2 m / min, and the dispersion is uniformly adhered to the surface of the copper wire using an immersion coating process. Step 3: Next, the copper wire with the attached dispersion is introduced into a hot air drying oven at 120°C and dried for 2 minutes to remove the ethanol solvent; Step 4: Finally, the dried copper wire is passed through a tube sintering furnace at a temperature of 380℃ and held at that temperature for 15 seconds under a nitrogen protective atmosphere to decompose polyvinylpyrrolidone and form a strong conductive coating of carbon nanotubes on the surface of the copper wire.

[0008] After coating process, the thickness of the carbon nanotube coating on the surface of the flexible tin-plated copper wire is controlled between 3μm and 5μm, and the volume resistivity of the coating is tested to be ≤1.5×10⁻⁶. -4 The adhesion strength reaches Ω·cm, meeting the Class 2 requirements of GB / T 5270-2005 standard. In this scheme, the thickness of the carbon nanotube coating is controlled between 3μm and 5μm, prepared using a coating process. It exhibits excellent conductivity and mechanical strength, effectively reducing the contact resistance changes of the flexible tin-plated copper wire during repeated bending, and enhancing the wear resistance and corrosion resistance of the copper wire surface, thereby extending the service life of the conductor core.

[0009] The carbon nanotube coating is a multi-walled carbon nanotube coating with a diameter distribution between 20 nm and 50 nm and a length between 5 μm and 10 μm. The axial direction of the carbon nanotubes is helically distributed at an angle of 30° to 60° to the axis of the flexible tin-plated copper wire. This helical multi-walled carbon nanotube structure provides better stress dispersion when the copper wire is bent, reducing cracks in the coating caused by bending. It also further enhances the adhesion between the coating and the copper wire substrate, ensuring that the carbon nanotube coating is not easily peeled off under long-term bending conditions, thus continuously enhancing its conductivity and wear resistance. Furthermore, X-ray photoelectron spectroscopy analysis of the multi-walled carbon nanotube coating shows that its surface oxygen content is controlled between 2 at% and 5 at%. An appropriate amount of oxygen-containing functional groups helps improve the interfacial compatibility between the coating and the subsequent insulation material, thereby improving the stability of the entire cable structure.

[0010] The insulating layer adopts a gradient composite structure, which includes an inner insulating layer, an intermediate insulating layer, and an outer insulating layer. The inner insulating layer is a soft thermoplastic polyurethane, the intermediate insulating layer is a semi-rigid polymer elastomer, and the outer insulating layer is a wear-resistant thermoplastic polyurethane. The total thickness is between 0.5 mm and 1.0 mm, and the hardness gradually increases from the inside to the outside.

[0011] In this design, the inner insulating layer is made of soft thermoplastic polyurethane with a Shore hardness of 75A, exhibiting excellent flexibility and elastic recovery. It can tightly adhere to the conductor core and buffer radial pressure during bending. The middle insulating layer is made of semi-rigid polymer elastomer with a Shore hardness of 85A. It is prepared by dynamic vulcanization using a blend of ethylene-vinyl acetate copolymer and nitrile rubber. Its elongation at break is ≥300%, and its tensile strength is ≥15MPa, effectively absorbing axial tensile stress during bending. The outer insulating layer is made of wear-resistant thermoplastic polyurethane with a Shore hardness of 95A. It contains 15% nano-sized alumina particles as a reinforcing phase. After melt blending in a twin-screw extruder, its wear resistance is tested according to ISO 4649 standard, with a volumetric wear of ≤20mm³, while maintaining an elastic recovery rate of over 80%, enabling it to resist wear caused by frequent friction in the cable chain system. This gradient composite structure, through the synergistic effect of the three layers of materials, not only ensures the overall flexibility of the insulation layer to adapt to bending requirements, but also improves the durability of the cable through the high hardness and wear resistance of the outer insulation layer. At the same time, the transition design of the middle insulation layer avoids the stress concentration phenomenon that is prone to occur when bending traditional single-material insulation layers.

[0012] The robot-use flex-resistant drag chain cable also includes an elastic micro-foamed buffer layer, which is disposed between the inner sheath layer and the braided layer. The elastic micro-foamed buffer layer is a closed-cell foamed thermoplastic elastomer with a thickness between 0.2 mm and 0.5 mm and a foaming rate between 30% and 50%.

[0013] The elastic microfoamed buffer layer uses a blend of styrene-butadiene-styrene block copolymer and polyolefin elastomer as the base material and is prepared by supercritical carbon dioxide foaming process. Its average cell diameter is controlled between 50μm and 150μm, and the cell density is ≥1×10⁻⁶. 6 Cells / cm³. This closed-cell structure effectively blocks the intrusion of moisture and impurities. Simultaneously, when the cable is subjected to impact or vibration, the compression and rebound of the cells absorb energy, reducing the impact on the internal conductor core and insulation layer. During bending, the elastic micro-foamed buffer layer adapts to the bending deformation of the cable, reducing the relative friction between the inner sheath and the braided layer. Its coefficient of friction (in contact with the braided layer) is tested to be ≤0.35 (under dry friction conditions), thus reducing the risk of wear. Furthermore, the buffer layer has a tensile strength ≥8MPa, an elongation at break ≥400%, and a compression set (70℃×22h) ≤25%, ensuring good elastic buffering performance and structural stability under long-term dynamic bending conditions, further improving the cable's bending fatigue life.

[0014] The nonwoven fabric layer includes an inner fabric layer and an outer fabric layer. The inner fabric layer is located between the woven layer and the inner sheath layer, and the outer fabric layer is located between the woven layer and the outer sheath layer. The nonwoven fabric layer is impregnated with polytetrafluoroethylene lubricant, and the coating thickness is between 0.1 mm and 0.3 mm.

[0015] The inner layer is made of 160g / m² polyester spunlace nonwoven fabric with a fiber diameter of 10μm to 20μm. It has good liquid absorption and air permeability, and can uniformly absorb polytetrafluoroethylene lubricant and form a stable lubricating film between the woven layer and the inner sheath layer. The outer layer is made of 200g / m² aramid fiber needle-punched nonwoven fabric with a fiber length of 5mm to 10mm. It forms a three-dimensional structure through needle punching and has a tensile strength ≥15N / 50mm, which can enhance the wrapping force of the woven layer and improve the storage capacity of the lubricant.

[0016] The polytetrafluoroethylene lubricant is made by compounding polytetrafluoroethylene micro powder with a particle size of 1μm to 5μm with methyl silicone oil at a mass ratio of 3:7. The viscosity is controlled between 500cSt and 1000cSt. After impregnation treatment, the oil content of the non-woven fabric layer reaches 25% to 35%.

[0017] During cable bending, when the braided layer moves relative to the inner and outer sheaths, the PTFE lubricant in the non-woven fabric layer slowly seeps out, reducing the coefficient of friction at the contact surfaces to below 0.2 (compared to 0.5 to 0.6 under dry friction conditions without lubricant impregnation). This effectively reduces wear on the braided layer during bending and avoids the problems of easy leakage and environmental pollution associated with traditional liquid lubricants, ensuring long-term lubrication. Furthermore, the PTFE lubricant exhibits excellent high-temperature resistance and chemical stability, maintaining stable performance within a temperature range of -50℃ to 200℃ without corroding or swelling other cable materials.

[0018] The braided layer includes an aluminum foil wrapping layer and a tin-plated copper-tin alloy braided layer. The thickness of the aluminum foil wrapping layer is 0.03 mm to 0.08 mm, and the diameter of a single tin-plated copper-tin alloy braided wire is between 0.10 mm and 0.25 mm, with a diameter tolerance of no more than 0.04 mm.

[0019] The aluminum foil wrapping layer uses double-sided composite aluminum foil (0.02mm thick aluminum foil, outer polyethylene film thickness 0.01mm to 0.06mm), spirally wrapped around the outside of the inner sheath layer with an overlap rate of 25% to 35%. Its optical shielding effectiveness is ≥85dB in the frequency range of 30MHz to 1GHz, effectively blocking the influence of external electromagnetic interference on cable signal transmission, while also having a certain degree of moisture resistance. The tin-plated copper-tin alloy copper foil wire braided layer is woven using a 16-spindle braiding machine, with a braiding density controlled at 85% to 90% and a braiding angle of 45°±5°. The tin-plated copper-tin alloy copper foil wire is formed by longitudinally shearing, continuous tin plating (tin layer thickness 2μm to 5μm) of copper-tin alloy strip with a thickness of 0.05mm to 0.1mm, followed by rolling. Its tensile strength is ≥450MPa, elongation is ≥15%, and it has higher bending fatigue strength and flexibility than traditional round copper wire.

[0020] During cable bending, the flat copper foil wires can better adapt to bending deformation, reduce stress concentration inside the braided layer, and its bending resistance (according to IEC 60228 standard, bending radius 5 times the cable diameter, 30 bends per minute) can reach more than 1 million times without breakage, which significantly improves the long-term reliability of the braided layer as a mechanical protection layer and auxiliary shielding layer of the cable.

[0021] The robot-use flexible drag chain cable also includes an integrated fiber optic sensor; the integrated fiber optic sensor is a single-mode fiber, which is embedded parallel to the conductor core layer and fixed in the insulation layer, and the integrated fiber optic sensor is connected to a data interface.

[0022] The integrated fiber optic sensor has a core diameter of 9μm, a cladding diameter of 125μm, and a 25μm thick polyimide coating. Its operating wavelength range covers two windows: 1310nm and 1550nm. The fiber optic sensor is fixed to the gap between the inner insulation layer and the conductor core layer via a micromechanical clamping structure. This clamping structure is injection molded from the same soft thermoplastic polyurethane material as the inner insulation layer, ensuring that the fiber does not shift relative to the cable during bending and preventing mechanical damage. The integrated fiber optic sensor can monitor the strain and temperature distribution of the cable in real time during use. When the cable undergoes excessive bending or localized overheating, accurate detection is achieved through changes in the fiber optic grating wavelength shift (strain sensitivity ≥1.2pm / με, temperature sensitivity ≥10pm / ℃), with a detection accuracy of ±5με (strain) and ±0.5℃ (temperature). The data interface uses an MPO miniature connector with IP67 protection, which can be directly connected to the robot control system to realize real-time transmission and analysis of detection data. This provides key data support for cable health status assessment and predictive maintenance, effectively avoiding robot downtime accidents caused by cable faults.

[0023] The outer sheath layer has a biomimetic spiral texture on its surface, with a texture depth between 0.1 mm and 0.3 mm, and the material is low-viscosity polyurethane mixed ceramic nanoparticles.

[0024] The pitch of the biomimetic spiral convex pattern is set to 1.5 to 2 times the cable diameter, and the cross-section of the convex pattern is arc-shaped with a radius of 0.05 mm to 0.15 mm. The low-viscosity polyurethane substrate is an aliphatic polyether polyurethane with a Shore hardness of 88A, which has excellent weather resistance and hydrolysis resistance. After adding 5% nano-alumina ceramic particles (particle size 50 nm to 100 nm) and melt-blending them in a twin-screw extruder, its surface friction coefficient (in contact with the cable chain track) is reduced to 0.25 (0.4 without ceramic particles). At the same time, the wear resistance is tested according to ISO 4649 standard, and the volumetric wear is further reduced to below 15 mm³.

[0025] Inspired by the crawling mechanism of arthropods, this biomimetic spiral structure transforms sliding friction into partial rolling friction as the cable reciprocates within the cable carrier system. This effectively reduces the contact area and frictional resistance between the cable and the cable carrier track, minimizing frictional heat generation. Furthermore, the spiral texture provides guidance during cable bending, reducing disordered swaying within the cable carrier and preventing entanglement or jamming with other cables or cable carrier components. Its low-viscosity properties prevent dust and debris from accumulating on the cable surface, maintaining cable cleanliness during operation. The addition of ceramic nanoparticles further enhances the surface hardness and wear resistance of the outer sheath, ensuring the textured structure remains durable and resistant to wear and deformation during long-term use, continuously fulfilling its drag-reduction and guiding functions.

[0026] The outer sheath is made of bio-based polyurethane material, and the cable end is integrated with a modular quick-connect end, which includes a spring pin contact and a waterproof shell.

[0027] Bio-based polyurethane material uses castor oil-based polyols as the main raw material (≥60%), which is polymerized through reaction with isophorone diisocyanate. It has a tensile strength ≥20MPa, elongation at break ≥450%, and Shore A hardness 85, exhibiting mechanical properties comparable to traditional petroleum-based polyurethanes. Simultaneously, its biodegradability (tested according to ASTM D5338 standard) exceeds 30%, significantly reducing the negative environmental impact of discarded cables. The modular quick-connect terminal's spring pin contact is made of beryllium copper alloy with a gold-plated surface (gold layer thickness ≥1μm). It has a single-pin rated current of 5A, contact resistance ≤20mΩ, and a mating life ≥1000 cycles. The waterproof shell is injection molded from PA66+GF30 material, with an internal fluororubber sealing ring, achieving an IP68 protection rating and allowing for long-term underwater operation at a depth of 1.5m. The terminal integrates a positioning guide pin and an anti-misinsertion structure to ensure accurate alignment of the plug and socket during connection, preventing equipment damage due to incorrect polarity. This modular design reduces cable installation and replacement time to one-third of traditional connection methods. The connection between the cable end and the outer sheath is achieved through an integrated injection molding process, with a peel strength of ≥15N / cm at the joint, ensuring that the cable will not detach during frequent bending and dragging, thus improving the overall reliability and ease of maintenance of the cable system.

[0028] The beneficial effects of this invention are as follows: 1. In this invention, the thickness of the carbon nanotube coating is controlled between 3μm and 5μm and is prepared by a coating process. It has excellent conductivity and mechanical strength, which can effectively reduce the change in contact resistance of flexible tin-plated copper wire during repeated bending and enhance the wear resistance and corrosion resistance of the copper wire surface, thereby extending the service life of the conductor core layer.

[0029] 2. The gradient composite structure of the insulation layer in this invention, through the synergistic effect of the three layers of materials, not only ensures the overall flexibility of the insulation layer to adapt to bending requirements, but also improves the durability of the cable through the high hardness and wear resistance of the outer insulation layer. At the same time, the transition design of the middle insulation layer avoids the stress concentration phenomenon that is prone to occur when bending traditional single-material insulation layers.

[0030] 3. In the cable bending process of this invention, the braided layer moves relative to the inner and outer sheath layers. The PTFE lubricant in the non-woven fabric layer slowly seeps out, reducing the coefficient of friction at the contact surface to below 0.2 (the coefficient of friction is 0.5 to 0.6 under dry friction conditions without lubricant impregnation). This effectively reduces wear on the braided layer during bending and avoids the problems of easy leakage and environmental pollution associated with traditional liquid lubricants, ensuring long-term lubrication. Furthermore, the PTFE lubricant has excellent high-temperature resistance and chemical stability, maintaining stable performance within a temperature range of -50℃ to 200℃ without corroding or swelling other cable materials.

[0031] 4. The biomimetic spiral structure design in this invention is inspired by the crawling mechanism of arthropods. When the cable reciprocates in the cable carrier system, the raised pattern can convert sliding friction into partial rolling friction, effectively reducing the contact area and frictional resistance between the cable and the cable carrier track, and reducing frictional heat generation. Furthermore, the spiral raised pattern can provide a certain guiding effect when the cable bends, reducing disorderly swaying of the cable inside the cable carrier and preventing entanglement or jamming with other cables or cable carrier components. The low-viscosity properties prevent dust and debris from accumulating on the cable surface, maintaining the cleanliness of the cable during operation. The addition of ceramic nanoparticles further enhances the surface hardness and wear resistance of the outer sheath, ensuring that the raised structure is not easily worn or deformed during long-term use, and continues to perform its drag-reducing and guiding functions. Attached Figure Description

[0032] The invention will now be further described with reference to the accompanying drawings.

[0033] Figure 1 This is a schematic cross-sectional view of the flex-resistant drag chain cable for robots according to the present invention; Figure 2 This is a schematic cross-sectional view of the conductor core layer and the insulating layer in this invention; In the figure: conductor core layer 1, flexible tin-plated copper wire 11, aramid fiber 12, carbon nanotube coating 13, insulation layer 2, inner insulation layer 21, middle insulation layer 22, outer insulation layer 23, inner sheath layer 3, braided layer 4, non-woven fabric layer 5, inner fabric 51, outer fabric 52, outer sheath layer 6, elastic micro-foamed buffer layer 7. 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 in conjunction with specific embodiments.

[0035] like Figures 1 to 2As shown, a flexural drag chain cable for robots includes a conductor core layer 1, an insulation layer 2, an inner sheath layer 3, a braided layer 4, a non-woven fabric layer 5, and an outer sheath layer 6. The insulation layer 2 wraps around the conductor core layer 1, the inner sheath layer 3 is located outside the insulation layer 2, the braided layer 4 covers the inner sheath layer 3, the non-woven fabric layer 5 is wound around the braided layer 4, and the outer sheath layer 6 wraps around the non-woven fabric layer 5. The conductor core layer 1 is formed by twisting multiple flexible tin-plated copper wires 11 with aramid fibers 12, and the surface of the flexible tin-plated copper wires 11 is coated with a carbon nanotube coating 13. The diameter of a single flexible tin-plated copper wire 11 is between 0.05 mm and 0.15 mm, and the diameter tolerance does not exceed 0.01 mm.

[0036] The coating process for carbon nanotube coating 13 is as follows: Step 1: First, add the carbon nanotube powder to a 5% (w / w) polyvinylpyrrolidone ethanol solution and ultrasonically disperse for 30 minutes to form a 0.8% carbon nanotube dispersion. Step 2: Then, the annealed flexible tin-plated copper wire 11 is passed through the dispersion bath at a speed of 1.2 m / min, and the dispersion is uniformly adhered to the surface of the copper wire by dip coating process; Step 3: Next, the copper wire with the attached dispersion is introduced into a hot air drying oven at 120°C and dried for 2 minutes to remove the ethanol solvent; Step 4: Finally, the dried copper wire is passed through a tube sintering furnace at a temperature of 380℃ and held at that temperature for 15 seconds under a nitrogen protective atmosphere to decompose polyvinylpyrrolidone and form a strong conductive coating of carbon nanotubes on the surface of the copper wire.

[0037] After the coating process, the thickness of the carbon nanotube coating 13 on the surface of the flexible tin-plated copper wire 11 is controlled between 3 μm and 5 μm, and the volume resistivity of the coating is tested to be ≤1.5×10⁻⁶. -4 The adhesion strength reaches Level 2 of GB / T 5270-2005 standard, with an Ω·cm. In this scheme, the thickness of the carbon nanotube coating 13 is controlled between 3μm and 5μm, prepared using a coating process. It exhibits excellent conductivity and mechanical strength, effectively reducing the contact resistance change of the flexible tin-plated copper wire 11 during repeated bending, and enhancing the wear resistance and corrosion resistance of the copper wire surface, thereby extending the service life of the conductor core layer 1.

[0038] The carbon nanotube coating 13 is a multi-walled carbon nanotube coating with a diameter distribution between 20 nm and 50 nm and a length between 5 μm and 10 μm. The axial direction of the carbon nanotubes is distributed at a helical angle of 30° to 60° with the axis of the flexible tin-plated copper wire 11. This helical multi-walled carbon nanotube structure provides better stress dispersion when the copper wire is bent, reducing cracks in the coating caused by bending. It also further enhances the adhesion between the coating and the copper wire substrate, ensuring that the carbon nanotube coating 13 is not easily peeled off under long-term bending conditions, thus continuously enhancing its conductivity and wear resistance. Furthermore, X-ray photoelectron spectroscopy analysis of the multi-walled carbon nanotube coating 13 shows that its surface oxygen content is controlled between 2 at% and 5 at%. An appropriate amount of oxygen-containing functional groups helps improve the interfacial compatibility between the coating and the subsequent insulation layer 2 material, thereby improving the stability of the entire cable structure.

[0039] like Figure 2 As shown, the insulating layer 2 adopts a gradient composite structure. The insulating layer 2 includes an inner insulating layer 21, an inner insulating layer 22, and an outer insulating layer 23. The inner insulating layer 21 is a soft thermoplastic polyurethane, the inner insulating layer 22 is a semi-rigid polymer elastomer, and the outer insulating layer 23 is a wear-resistant thermoplastic polyurethane. The total thickness is between 0.5 mm and 1.0 mm, and the hardness gradually increases from the inside to the outside.

[0040] In this design, the inner insulating layer 21 is a soft thermoplastic polyurethane with a Shore hardness of 75A, exhibiting excellent flexibility and elastic recovery. It can tightly adhere to the conductor core layer 1 and buffer the radial pressure during bending. The middle insulating layer 22 is a semi-rigid polymer elastomer with a Shore hardness of 85A. It is a semi-rigid polymer elastomer prepared by a blending system of ethylene-vinyl acetate copolymer and nitrile rubber through a dynamic vulcanization process. Its elongation at break is ≥300%, and its tensile strength is ≥15MPa, effectively absorbing axial tensile stress during bending. The outer insulating layer 23 is a wear-resistant thermoplastic polyurethane with a Shore hardness of 95A. It contains 15% nano-sized alumina particles as a reinforcing phase. After melt blending in a twin-screw extruder, its wear resistance is tested according to ISO 4649 standard, with a volumetric wear amount ≤20mm³, while maintaining an elastic recovery rate of over 80%, which can resist the wear caused by frequent friction in the cable chain system. This gradient composite structure, through the synergistic effect of the three layers of materials, not only ensures the overall flexibility of the insulation layer 2 to adapt to bending requirements, but also improves the durability of the cable through the high hardness and wear resistance of the outer insulation layer 23. At the same time, the transition design of the middle insulation layer 22 avoids the stress concentration phenomenon that is prone to occur when bending the traditional single-material insulation layer 2.

[0041] like Figure 1As shown, the robot flexible drag chain cable also includes an elastic micro-foamed buffer layer 7, which is disposed between the inner sheath layer 3 and the braided layer 4. The elastic micro-foamed buffer layer 7 is a closed-cell foamed thermoplastic elastomer with a thickness between 0.2 mm and 0.5 mm and a foaming rate between 30% and 50%.

[0042] The elastic microfoamed buffer layer 7 is prepared using a blend of styrene-butadiene-styrene block copolymer and polyolefin elastomer as the base material through a supercritical carbon dioxide foaming process. Its average pore diameter is controlled between 50 μm and 150 μm, and its pore density is ≥1×10⁻⁶. 6 Cells / cm³. This closed-cell structure effectively blocks the intrusion of moisture and impurities. Simultaneously, when the cable is subjected to impact or vibration, the compression and rebound of the cells absorb energy, reducing the impact on the internal conductor core layer 1 and insulation layer 2. During bending, the elastic micro-foamed buffer layer 7 adapts to the bending deformation of the cable, reducing the relative friction between the inner sheath layer 3 and the braided layer 4. Its coefficient of friction (in contact with the braided layer 4) is tested to be ≤0.35 (under dry friction conditions), thereby reducing the risk of wear. Furthermore, the buffer layer has a tensile strength ≥8MPa, an elongation at break ≥400%, and a compression set (70℃×22h) ≤25%, ensuring good elastic buffering performance and structural stability under long-term dynamic bending conditions, further improving the cable's bending fatigue life.

[0043] like Figure 1 As shown, the nonwoven fabric layer 5 includes an inner fabric layer 51 and an outer fabric layer 52. The inner fabric layer 51 is located between the braided layer 4 and the inner sheath layer 3, and the outer fabric layer 52 is located between the braided layer 4 and the outer sheath layer 6. The nonwoven fabric layer 5 is impregnated with polytetrafluoroethylene lubricant, and the coating thickness is between 0.1 mm and 0.3 mm.

[0044] The inner layer fabric 51 is made of 160g / m² polyester fiber spunlace nonwoven fabric with a fiber diameter of 10μm to 20μm. It has good liquid absorption and air permeability, and can uniformly absorb polytetrafluoroethylene lubricant and form a stable lubricating film between the braided layer 4 and the inner sheath layer 3. The outer layer fabric 52 is made of 200g / m² aramid 12 fiber needle-punched nonwoven fabric with a fiber length of 5mm to 10mm. It forms a three-dimensional structure through needle punching and has a tensile strength ≥15N / 50mm. It can enhance the wrapping force of the braided layer 4 and improve the storage capacity of the lubricant.

[0045] The polytetrafluoroethylene lubricant is made by compounding polytetrafluoroethylene micro powder with a particle size of 1μm to 5μm with methyl silicone oil at a mass ratio of 3:7. The viscosity is controlled between 500cSt and 1000cSt. After impregnation treatment, the oil content of the nonwoven fabric layer 5 reaches 25% to 35%.

[0046] During cable bending, when the braided layer 4 moves relative to the inner sheath layer 3 and the outer sheath layer 6, the polytetrafluoroethylene (PTFE) lubricant in the nonwoven layer 5 slowly seeps out, reducing the coefficient of friction of the contact surface to below 0.2 (the coefficient of friction is 0.5 to 0.6 under dry friction conditions without lubricant impregnation). This effectively reduces the wear of the braided layer 4 during bending and avoids the problems of easy leakage and environmental pollution associated with traditional liquid lubricants, ensuring long-term lubrication. Furthermore, the PTFE lubricant also has excellent high-temperature resistance and chemical stability, maintaining stable performance within a temperature range of -50℃ to 200℃ without corroding or swelling other cable materials.

[0047] The braided layer 4 includes an aluminum foil wrapping layer and a tin-plated copper-tin alloy braided layer. The thickness of the aluminum foil wrapping layer is 0.03 mm to 0.08 mm, and the diameter of a single tin-plated copper-tin alloy braided wire is between 0.10 mm and 0.25 mm, with a diameter tolerance of no more than 0.04 mm.

[0048] The aluminum foil wrapping layer uses double-sided composite aluminum foil (0.02mm thick aluminum foil, outer polyethylene film thickness 0.01mm to 0.06mm), spirally wrapped around the outside of the inner sheath layer 3 with an overlap rate of 25% to 35%. Its optical shielding effectiveness is ≥85dB in the frequency range of 30MHz to 1GHz, effectively blocking the influence of external electromagnetic interference on cable signal transmission, while also having a certain degree of moisture resistance. The tin-plated copper-tin alloy copper foil wire braided layer is woven using a 16-spindle braiding machine, with a braiding density controlled at 85% to 90% and a braiding angle of 45°±5°. The tin-plated copper-tin alloy copper foil wire is formed by longitudinally shearing, continuous tin plating (tin layer thickness 2μm to 5μm) of copper-tin alloy strip with a thickness of 0.05mm to 0.1mm, followed by rolling. Its tensile strength is ≥450MPa, elongation is ≥15%, and it has higher bending fatigue strength and flexibility than traditional round copper wire.

[0049] During the cable bending process, the flat copper foil wires can better adapt to bending deformation, reduce stress concentration inside the braided layer 4, and its bending resistance (according to IEC 60228 standard, bending radius 5 times the cable diameter, 30 bends per minute) can reach more than 1 million times without breakage, which significantly improves the long-term reliability of the braided layer 4 as the cable mechanical protection layer and auxiliary shielding layer.

[0050] The robot-use flexible drag chain cable also includes an integrated fiber optic sensor; the integrated fiber optic sensor is a single-mode fiber, which is embedded parallel to the conductor core layer 1 and fixed in the insulation layer 2, and the integrated fiber optic sensor is connected to a data interface.

[0051] The integrated fiber optic sensor has a core diameter of 9 μm, a cladding diameter of 125 μm, and a 25 μm thick polyimide coating. Its operating wavelength range covers two windows: 1310 nm and 1550 nm. The fiber optic sensor is fixed to the gap between the inner layer of the insulation layer 2 and the conductor core layer 1 via a micromechanical clamping structure. This clamping structure is injection molded from the same soft thermoplastic polyurethane material as the inner layer of the insulation layer 2, ensuring that the fiber does not undergo relative displacement during cable bending and preventing mechanical damage to the fiber. The integrated fiber optic sensor can monitor the strain changes and temperature distribution of the cable in real time during use. When the cable undergoes excessive bending or localized overheating, accurate detection is achieved through changes in the fiber grating wavelength shift (strain sensitivity ≥ 1.2 pm / με, temperature sensitivity ≥ 10 pm / ℃), with a detection accuracy of ±5 με (strain) and ±0.5℃ (temperature). The data interface uses an MPO miniature connector with IP67 protection, which can be directly connected to the robot control system to realize real-time transmission and analysis of detection data. This provides key data support for cable health status assessment and predictive maintenance, effectively avoiding robot downtime accidents caused by cable faults.

[0052] The outer sheath layer 6 has a biomimetic spiral texture on its surface, with a texture depth between 0.1 mm and 0.3 mm, and the material is low-viscosity polyurethane mixed ceramic nanoparticles.

[0053] The pitch of the biomimetic spiral convex pattern is set to 1.5 to 2 times the cable diameter, and the cross-section of the convex pattern is arc-shaped with a radius of 0.05 mm to 0.15 mm. The low-viscosity polyurethane substrate is an aliphatic polyether polyurethane with a Shore hardness of 88A, which has excellent weather resistance and hydrolysis resistance. After adding 5% nano-alumina ceramic particles (particle size 50 nm to 100 nm) and melt-blending them in a twin-screw extruder, its surface friction coefficient (in contact with the cable chain track) is reduced to 0.25 (0.4 without ceramic particles). At the same time, the wear resistance is tested according to ISO 4649 standard, and the volumetric wear is further reduced to below 15 mm³.

[0054] Inspired by the crawling mechanism of arthropods, this biomimetic spiral structure transforms sliding friction into partial rolling friction as the cable reciprocates within the cable carrier system. This effectively reduces the contact area and frictional resistance between the cable and the cable carrier track, thus minimizing frictional heat generation. Furthermore, the spiral texture provides guidance during cable bending, reducing disordered swaying within the cable carrier and preventing entanglement or jamming with other cables or cable carrier components. Its low-viscosity properties prevent dust and debris from accumulating on the cable surface, maintaining cable cleanliness during operation. The addition of ceramic nanoparticles further enhances the surface hardness and wear resistance of the outer sheath layer 6, ensuring the textured structure remains durable and resistant to wear and deformation during long-term use, continuously fulfilling its drag-reduction and guiding functions.

[0055] The outer sheath layer 6 is made of bio-based polyurethane material, and the cable end is integrated with a modular quick-connect end, which includes a spring pin contact and a waterproof shell.

[0056] Bio-based polyurethane material uses castor oil-based polyols as the main raw material (≥60%), which is polymerized through reaction with isophorone diisocyanate. It has a tensile strength ≥20MPa, elongation at break ≥450%, and Shore A hardness 85, exhibiting mechanical properties comparable to traditional petroleum-based polyurethanes. Simultaneously, its biodegradability (tested according to ASTM D5338 standard) exceeds 30%, significantly reducing the negative environmental impact of discarded cables. The modular quick-connect terminal's spring pin contact is made of beryllium copper alloy with a gold-plated surface (gold layer thickness ≥1μm). It has a single-pin rated current of 5A, contact resistance ≤20mΩ, and a mating life ≥1000 cycles. The waterproof shell is injection molded from PA66+GF30 material, with an internal fluororubber sealing ring, achieving an IP68 protection rating and allowing for long-term underwater operation at a depth of 1.5m. The terminal integrates a positioning guide pin and an anti-misinsertion structure to ensure accurate alignment of the plug and socket during connection, preventing equipment damage due to incorrect polarity. This modular design reduces cable installation and replacement time to one-third of traditional connection methods. The end is connected to the cable outer sheath 6 through an integrated injection molding process, and the peel strength of the joint is ≥15N / cm, ensuring that it will not fall off during frequent bending and dragging, thus improving the overall reliability and maintenance convenience of the cable system.

[0057] Working principle: When the robot's flexible drag chain cable is in operation, the multiple strands of flexible tin-plated copper wires 11 in the conductor core layer 1, through spiral twisting and synergistic effect with the carbon nanotube coating 13, ensure stable conductivity during repeated bending. The spiral distribution and specific oxygen content of the carbon nanotube coating 13 effectively enhance its wear resistance, corrosion resistance, and interfacial compatibility with the insulation layer 2. The gradient composite structure of the insulation layer 2, from the flexible buffering of the inner 75A soft thermoplastic polyurethane, to the stress absorption of the middle 85A semi-rigid polymer elastomer, and then to the wear-resistant protection of the outer 95A wear-resistant thermoplastic polyurethane (containing 15% nano-alumina), achieves a balance between insulation, buffering, and wear resistance. When the cable undergoes bending motion, the elastic micro-foamed buffer layer 7 (closed-cell foamed thermoplastic elastomer, with a cell diameter of 50μm-150μm) between the inner sheath layer 3 and the braided layer 4 absorbs impact and vibration energy through the compression and rebound of the cells, and reduces interlayer friction. The aluminum foil wrapping layer in braided layer 4 provides shielding effectiveness of ≥85dB, while the flat tin-plated copper-tin alloy braided layer (withstanding bending ≥1 million cycles) ensures mechanical strength while adapting to bending deformation. The PTFE lubricant (oil content 25%-35%) in non-woven layer 5 seeps out during interlayer relative movement, reducing the coefficient of friction to below 0.2 and minimizing wear on braided layer 4. The biomimetic spiral texture of the outer sheath layer 6 (pitch 1.5-2 times the cable diameter, containing 5% nano-alumina) converts sliding friction into partial rolling friction, reducing frictional resistance and heat generation with the cable chain track. Its bio-based polyurethane material balances mechanical performance and environmental friendliness. An integrated fiber optic sensor (strain sensitivity ≥1.2pm / με, temperature sensitivity ≥10pm / ℃) monitors cable strain and temperature in real time, transmitting data to the robot control system via an MPO interface. Modular quick-connect terminals (IP68 protection, insertion / extraction life ≥1000 cycles) enable rapid and reliable cable connection and maintenance. The coordinated operation of all components enables the cable to maintain stable signal transmission and power supply over a long period of time, even under complex working conditions such as frequent bending, friction, and impact in the robotic cable chain system, and also provides condition monitoring and predictive maintenance capabilities.

[0058] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A winding-resistant drag chain cable for robots, comprising a conductor core layer (1), an insulation layer (2), an inner sheath layer (3), a braided layer (4), a non-woven fabric layer (5) and an outer sheath layer (6), the insulation layer (2) wrapping the conductor core layer (1), the inner sheath layer (3) being outside the insulation layer (2), the braided layer (4) covering the inner sheath layer (3), the non-woven fabric layer (5) being wound around the braided layer (4), and the outer sheath layer (6) wrapping the non-woven fabric layer (5), characterized in that: the conductor core layer (1) is composed of a plurality of flexible tin-plated copper wires (11) twisted with aramid (12), and the flexible tin-plated copper wires (11) are coated with a carbon nanotube coating (13). The carbon nanotube coating (13) is a multi-walled carbon nanotube coating, with a tube diameter distribution of 20-50 nm, a length of 5-10 μm, and a spiral angle of 30-60° between the axial direction of the carbon nanotube and the axis of the flexible tin-plated copper wire (11).

2. A bend resistant towline cable for a robot according to claim 1, characterized in that: The insulation layer (2) adopts a gradient composite structure, and comprises an inner insulation layer (21), a middle insulation layer (22) and an outer insulation layer (23), the inner insulation layer (21) being soft thermoplastic polyurethane, the middle insulation layer (22) being semi-hard high polymer elastomer, and the outer insulation layer (23) being wear-resistant thermoplastic polyurethane, with a total thickness of 0.5-1.0 mm and a gradually increasing hardness from inside to outside.

3. A bend resistant towline cable for a robot according to claim 1, characterized in that: An elastic micro-foamed buffer layer (7) is further included, which is arranged between the inner sheath layer (3) and the braided layer (4), and is a closed-cell foamed thermoplastic elastomer with a thickness of 0.2-0.5 mm and a foaming rate of 30-50%.

4. A bend resistant towline cable for a robot according to claim 1, characterized in that: The non-woven fabric layer (5) comprises an inner cloth (51) and an outer cloth (52), the inner cloth (51) being arranged between the braided layer (4) and the inner sheath layer (3), and the outer cloth (52) being arranged between the braided layer (4) and the outer sheath layer (6); the non-woven fabric layer (5) is impregnated with a polytetrafluoroethylene lubricant, with a coating thickness of 0.1-0.3 mm.

5. A bend resistant towline cable for a robot according to claim 1, characterized in that: The braided layer (4) comprises an aluminum foil wrapping layer and a tin-plated copper-tin alloy copper foil wire braided layer, the aluminum foil wrapping layer having a thickness of 0.03-0.08 mm, and the tin-plated copper-tin alloy copper foil wire having a single wire diameter of 0.10-0.25 mm with a diameter tolerance of no more than 0.04 mm.

6. A bend resistant towline cable for a robot according to claim 1, characterized in that: An integrated optical fiber sensor is further included, which is a single-mode optical fiber parallelly embedded beside the conductor core layer (1) and fixed in the insulation layer (2), and connected with a data interface.

7. A bend-limiting cable for a robotic drag chain, according to claim 1, wherein: The outer sheath layer (6) has a biomimetic spiral relief on the surface, with a relief depth of 0.1-0.3 mm and a material of low-viscosity polyurethane mixed with ceramic nanoparticles.

8. A bend limiting cable for a robotic drag chain cable as defined in claim 1, wherein: The outer sheath layer (6) is made of a bio-based polyurethane material, and a modular quick connection end head is integrated at the cable end, the end head comprising a spring needle contact and a waterproof shell.

9. A bend-limiting cable for a robotic drag chain, according to claim 1, wherein: ​

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