Bend-resistant cable for a humanoid robot joint

Abstract

The application discloses a kind of body robot joints with bending-resistant cable, it is related to cable technical field.The bending-resistant cable of the application includes 4 conductors and the insulating layer covered in the outside of 4 conductors in the form of spiral twist. Among them, the conductor is made of 18-20 silver copper alloy filaments by stranding treatment;Insulating layer is made of modified ETFE granules.Modified ETFE granules include the following mass parts of raw materials: ethylene-tetrafluoroethylene copolymer granules 900-1000 parts, modified porous particles 65-70 parts, core-shell stabilizer 13-15 parts, antioxidant 5.3-6 parts.In the application, the introduction of modified porous particles, core-shell stabilizer and other raw materials, and the spiral twist coating process treatment to the wire simultaneously improves the torsional life, bending life, bending resistance at low temperature, heat aging resistance and heat resistance of the cable for the joint of body robot.

Description

Technical Field

[0001] This invention relates to the field of cable technology, and more specifically to a bend-resistant cable for the joints of a robot. Background Technology

[0002] Embossed robots are the core carriers for the interaction between next-generation artificial intelligence technology and the physical world, and have already achieved large-scale applications in fields such as industrial precision assembly, minimally invasive medical surgery, polar special exploration, and home services. As the core motion execution unit of embossed robots, the joints, along with their associated cables, bear the critical functions of power transmission, control signal transmission, and multimodal data interaction. The reliability of these cables directly determines the robot's motion accuracy, continuous working time, and overall lifespan. As embossed robots develop towards higher degrees of freedom, higher integration, and all-weather operation, the requirements for the dynamic fatigue performance and environmental adaptability of the cables are becoming increasingly stringent.

[0003] However, in practical engineering applications, existing cables for omnidirectional robot joints still have the following performance shortcomings: First, insufficient dynamic fatigue life. Ordinary insulation materials have low molecular chain orientation and lack effective structural locking, making them prone to insulation layer cracking and conductor core breakage after long-term repeated torsion and bending. Second, poor low-temperature bending resistance. Existing insulation materials are prone to glass transition below low temperatures, resulting in a sharp decrease in flexibility, which cannot meet the requirements of low-temperature scenarios such as cold storage, outdoor winters, and high altitudes. Third, poor heat aging resistance. The frictional heat generated by joint movement and the heat dissipation of the motor cause local temperatures to remain above 100°C for extended periods, making insulation materials prone to thermo-oxidative degradation. Furthermore, traditional small-molecule light stabilizers are prone to migration and precipitation, accelerating performance degradation. Fourth, there is an inherent contradiction between integration and performance. To improve mechanical properties, insulation thickness is often increased or multi-layer composite structures are adopted, leading to an increase in cable outer diameter and a decrease in flexibility, making it difficult to adapt to the compact installation space of high-degree-of-freedom joints. Therefore, the torsion life, bending life, low-temperature bending resistance, heat aging resistance, and heat resistance of existing cables for omnidirectional robot joints still need systematic improvement. Summary of the Invention

[0004] The purpose of this invention is to provide a bend-resistant cable for the joints of a robot, solving the following technical problems: Existing cables used for the joints of automata still suffer from poor torsional life, bending life, low-temperature bending resistance, heat aging resistance, and heat resistance.

[0005] The objective of this invention can be achieved through the following technical solutions: A bend-resistant cable for the joints of a body-worn robot, the bend-resistant cable comprising four conductors and an insulating layer wrapped around the four conductors in a helical twist; The conductor is made of 18-20 silver-copper alloy monofilaments twisted together. The insulating layer is made of modified ETFE granules; the modified ETFE granules comprise the following raw materials in parts by weight: 900-1000 parts of ethylene-tetrafluoroethylene copolymer granules, 65-70 parts of modified porous particles, 13-15 parts of core-shell stabilizer, and 5.3-6 parts of antioxidant. The modified porous particles are thermoplastic polyimide that is first ball-milled and then surface-treated with oxygen plasma, then grafted with perfluorohexylethyltrimethoxysilane and finally foamed with supercritical carbon dioxide. The core-shell stabilizer is an anionic fluorinated hindered amine prepared by reacting 4-amino-2,2,6,6-tetramethylpiperidine and perfluorohexylethylsulfonyl fluoride. It is then intercalated into the interlayer of magnesium-aluminum layered bimetallic hydroxide nanosheets via an ion exchange reaction, and finally coated with a silica shell by a sol-gel method.

[0006] Preferably, the modified porous particles are prepared by the following method: Thermoplastic polyimide was ball-milled at 400 r / min for 16 h, then subjected to oxygen plasma treatment at 100 W for 10 min. After that, it was added to anhydrous ethanol, along with perfluorohexylethyltrimethoxysilane and glacial acetic acid, and stirred at 60 °C for 6 h. The mixture was then filtered, washed, and dried. Subsequently, it was placed in a supercritical carbon dioxide foaming reactor and maintained at a pressure of 22 MPa and a temperature of 230-240 °C for 2.5 h. Finally, the pressure was rapidly released within 10 s to obtain modified porous particles.

[0007] Preferably, the mass ratio of the thermoplastic polyimide, anhydrous ethanol, perfluorohexylethyltrimethoxysilane, and glacial acetic acid is 100:950-1000:5:0.5.

[0008] Preferably, the core-shell stabilizer is prepared as follows: A1: Add 4-amino-2,2,6,6-tetramethylpiperidine and triethylamine to anhydrous dichloromethane, then cool to 0°C, add perfluorohexylethylsulfonyl fluoride dropwise, then heat to 25-35°C and react for 12 h, filter, remove the solvent by vacuum distillation of the filtrate, then dissolve in anhydrous ethanol, finally add sodium chloroacetate and sodium hydroxide and reflux at 80°C for 10-12 h, cool and adjust the pH to 2-3, then filter, wash the precipitate and dry to obtain anionic fluorinated hindered amine; A2: Add magnesium-aluminum layered bimetallic hydroxide nanosheets to deionized water and ultrasonically disperse for 20-30 min. Then add anionic fluorine-containing hindered amine and adjust the pH to 8.5. Stir at 80℃ under nitrogen atmosphere for 24 h. After filtration, wash the precipitate and dry it to obtain hindered amine intercalated nanosheets. A3: Add hindered amine intercalated nanosheets to a mixture of anhydrous ethanol and deionized water and disperse ultrasonically for 20-30 min. Then adjust the pH to 9-10, add tetraethyl orthosilicate dropwise and stir at 40℃ for 4 h. After filtration, wash the precipitate and dry it to obtain the core-shell stabilizer.

[0009] Preferably, the amounts of anhydrous dichloromethane, 4-amino-2,2,6,6-tetramethylpiperidine, triethylamine, perfluorohexyl ethyl sulfonyl fluoride, anhydrous ethanol, sodium chloroacetate, and sodium hydroxide in A1 are 500-520 mL: 15.6 g: 10.1 g: 32.8 g: 300 mL: 11.7 g: 8 g.

[0010] Preferably, the ratio of deionized water, magnesium-aluminum layered bimetallic hydroxide nanosheets, and anionic fluorinated hindered amine in A2 is 1000-1200 mL: 15 g: 24-25 g.

[0011] Preferably, the ratio of anhydrous ethanol, deionized water, hindered amine intercalated nanosheets, and tetraethyl orthosilicate in A3 is 1000mL:200mL:15-16g:9g.

[0012] Preferably, the method for preparing the bend-resistant cable is as follows: S1: Mix ethylene-tetrafluoroethylene copolymer granules, modified porous particles, core-shell stabilizer, and antioxidant, then melt-blend and extrude, followed by water cooling and pelletizing to obtain modified ETFE granules. S2: Twist 18-20 silver-copper alloy monofilaments together to form a conductor, and prepare a total of 4 identical conductors; S3: Four conductors are arranged in parallel and passed through the center positioning mold of a single screw extruder with a rotating head. Modified ETFE granules are then added to the extruder. The extruder and rotating head are then started, causing the head to drive the four conductors to rotate synchronously forward at a speed of 15 r / min. At the same time, the traction speed is set to 3 m / min and the extrusion stretch ratio is controlled to 2.0. The molten modified ETFE simultaneously coats the four conductors in a spiral twisting manner to form an insulation layer, resulting in a single four-core cable. S4: After heat setting of a single four-core cable at 190℃ for 40s, it is water-cooled, dried, and then irradiated in a nitrogen atmosphere. After cross-linking heat treatment at 220℃ in a nitrogen atmosphere for 30min, the surface is lubricated with talc powder aqueous dispersion and finally wound up to obtain a bend-resistant cable.

[0013] Preferably, in step S3, after the four conductors pass through the mold, there is a gap between the four conductors and they do not contact each other; The spiral direction of the insulating layer described in S3 is opposite to the twisting direction of the conductor filaments.

[0014] Preferably, the electron beam irradiation dose during the irradiation treatment in S4 is 150 kGy; The mass fraction of the talc powder aqueous dispersion in S4 is 0.3%.

[0015] The beneficial effects of this invention are: This invention provides a bend-resistant cable for the joints of androids. The invention improves the torsional life, bending life, low-temperature bending resistance, heat aging resistance and heat resistance of the cable for the joints of androids simultaneously through the following methods.

[0016] (1) The modified porous particles of this invention are porous thermoplastic polyimide microspheres with fluorine-containing segments grafted onto their surfaces. Their porous structure can blunt crack tips or force cracks to deflect and branch, dissipating crack propagation energy and delaying the generation and propagation of fatigue cracks. The fluorine segments on the surface are highly compatible with the ethylene-tetrafluoroethylene copolymer matrix, effectively preventing particle-matrix interface debonding under cyclic stress, thereby inhibiting severe stress concentration and reducing oxygen and moisture penetration at the interface during aging, further improving the material's aging resistance. Thermoplastic polyimide has a much higher rigidity than the matrix resin, and at high temperatures, it can act as a physical crosslinking point and skeleton, limiting the large-scale slippage of the matrix molecular chains and reducing the thermal deformation rate. Its microporous structure reduces tensile strength to some extent, but can significantly improve fracture toughness through various toughening mechanisms.

[0017] (2) The core-shell stabilizer of the present invention is a composite particle with a fluorinated hindered amine intercalated magnesium-aluminum layered bimetallic hydroxide as the core and silica as the shell. The fluorinated hindered amine group has higher free radical capture efficiency and thermal stability, which can efficiently capture free radicals generated during thermo-oxidative aging and inhibit the breakage of matrix molecular chains; the intercalation structure further delays the migration and volatilization of hindered amine, making the stabilizing effect more durable; the outer silica shell can further block oxygen and slow down heat conduction, while avoiding direct stacking and agglomeration between nanosheets, so that they are uniformly dispersed at the nanoscale, playing a nano-reinforcing role, which helps to improve tensile strength and fracture toughness.

[0018] (3) The spiral torsion coating process of this invention uses a rotating die head to coat four parallel conductors with molten insulating resin in a spiral path at once, forming an integrated structure in which the insulation layer and conductors spiral synchronously. During torsion, deformation and stress are evenly distributed along the spiral direction, avoiding the high stress concentration at the interface between the conductor and the insulation layer in the parallel direct extrusion structure, thereby preventing interface shear failure and conductor core breakage, and significantly improving the torsion life compared with the ordinary direct extrusion process. During bending, the spiral structure can make the bending deformation uniform along the circumference and axis, avoiding the insulation layer cracking caused by excessive local bending, and significantly improving the bending life compared with the ordinary direct extrusion process. One spiral coating directly realizes multi-core insulation and cabling, with fixed and uniform conductor spacing, eliminating the uneven conductor stress and insulation pre-damage that may be caused by the traditional stranding process.

[0019] Meanwhile, modified porous particles provide stress dissipation and crack passivation capabilities at the microscale, core-shell stabilizers ensure chemical and structural stability during long-term use at the molecular scale, and the helical torsion coating process achieves uniform stress distribution at the macroscopic structural level. The synergistic effect of these three components enables the cable to maintain excellent thermo-oxidative aging and heat deformation resistance while achieving superior dynamic bending and torsional fatigue performance even at extreme low temperatures. This meets the long-term reliable use requirements of robotic joints under high-frequency, large-angle, and wide-temperature conditions.

[0020] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. The embodiments described below are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] Unless otherwise specified, the following information pertains to some of the raw materials used in the following embodiments and comparative examples of this invention: Thermoplastic polyimide, brand name: SABIC Ultem 1000; magnesium aluminum layered bimetallic hydroxide nanosheets purchased from Xi'an Ruixi Biotechnology Co., Ltd., with a particle size of 30-50nm and interlayer anions of carbonate; ethylene-tetrafluoroethylene copolymer granules, brand name: Chemours Tefzel HT-2181.

[0023] Example 1: A method for preparing a bend-resistant cable for the joints of a robot is as follows: S1: 100g of thermoplastic polyimide was added to a planetary ball mill cooled by liquid nitrogen and ball-milled at 400r / min for 16h. After removal, it was subjected to oxygen plasma treatment at 100W power for 10min. Then it was added to 950g of anhydrous ethanol, along with 5g of perfluorohexylethyltrimethoxysilane and 0.5g of glacial acetic acid. The mixture was stirred at 60℃ for 6h. The mixture was then filtered and the precipitate was washed three times with anhydrous ethanol. After drying under vacuum at 120℃ for 12h, it was placed in a supercritical carbon dioxide foaming reactor and kept at a pressure of 22MPa and a temperature of 230℃ for 2.5h. Finally, the pressure was rapidly released within 10s to obtain modified porous particles. S2: 15.6 g of 4-amino-2,2,6,6-tetramethylpiperidine and 10.1 g of triethylamine were added to 500 mL of anhydrous dichloromethane. The mixture was then cooled to 0 °C in an ice bath, and 32.8 g of perfluorohexyl ethyl sulfonyl fluoride was added dropwise. The mixture was then heated to 25 °C and reacted for 12 h. After filtration, the solvent was removed by vacuum distillation of the filtrate. The filtrate was then dissolved in 300 mL of anhydrous ethanol. Finally, 11.7 g of sodium chloroacetate and 8 g of sodium hydroxide were added, and the mixture was refluxed at 80 °C for 10 h. After cooling, the pH was adjusted to 2 with a 1 mol / L hydrochloric acid aqueous solution. The mixture was then filtered, and the precipitate was washed three times with deionized water. After vacuum drying at 60 °C for 8 h, an anionic fluorinated hindered amine was obtained. S3: Add 15g of magnesium-aluminum layered bimetallic hydroxide nanosheets to 1000mL of deionized water and ultrasonically disperse for 20min. Then add 24g of anionic fluorine-containing hindered amine and adjust the pH to 8.5 with 1mol / L sodium hydroxide aqueous solution. Stir for 24h at 80℃ under nitrogen atmosphere. After filtration, wash the precipitate 5 times with deionized water. Finally, vacuum dry at 80℃ for 12h to obtain hindered amine intercalated nanosheets. S4: Add 15g of hindered amine intercalated nanosheets to a mixture of 1000mL anhydrous ethanol and 200mL deionized water and ultrasonically disperse for 20min. Then adjust the pH to 9 with 25% ammonia water. Add 9g of tetraethyl orthosilicate and stir at 40℃ for 4h. After filtration, wash the precipitate three times with anhydrous ethanol. Finally, vacuum dry at 120℃ under nitrogen atmosphere for 12h to obtain the core-shell stabilizer. S5: 900g of ethylene-tetrafluoroethylene copolymer granules, 65g of modified porous particles, 13g of core-shell stabilizer, 3.5g of antioxidant 168, and 1.8g of antioxidant 1098 are mixed at 1500r / min for 5min. Then, the mixture is fed into a co-rotating twin-screw extruder and subjected to melt blending extrusion at barrel temperatures of 260℃, 275℃, 285℃, and 290℃, a die temperature of 300℃, and a screw speed of 200r / min. After water cooling and pelletizing, modified ETFE granules are obtained. S6: 18 silver-copper alloy monofilaments (0.03mm in diameter) are twisted together to form a cross-sectional area of ​​0.014mm². 2 Four identical conductors were prepared in total. S7: Arrange the four conductors in parallel and pass them through the center positioning die of a single-screw extruder (L / D ratio 25:1) with a rotating die head. The die ensures that the four conductors maintain a uniform spacing and do not contact each other. Then, add the modified ETFE granules to the extruder, which has a feeding section of 280°C, a melting section of 290°C, and a die head of 300°C. Start the extruder and rotating die head, causing the die head to drive the four conductors forward synchronously at a speed of 15 r / min. Simultaneously, set the traction speed to 3 m / min and control the extrusion draw ratio. 2.0 (ratio of extrusion die cross-sectional area to final insulation cross-sectional area): Molten modified ETFE is extruded through the spiral flow channel of the rotating die head, simultaneously coating the four conductors in a spiral twisting manner to form a uniform and continuous insulation layer (the spiral direction of the insulation layer is opposite to the twisting direction of the conductor filaments), directly obtaining a single four-core cable (cable outer diameter is 1.5mm, average insulation layer thickness is 0.35mm, thinnest point thickness is ≥0.32mm, thickness deviation is ≤±0.03mm, insulation layer concentricity is ≥90%). S8: After heat setting of a single four-core cable at 190℃ for 40s, it is water cooled in a 10℃ water bath for 10s. After drying, it is irradiated with an electron beam dose of 150kGy in a nitrogen atmosphere, and then crosslinked heat treatment is performed at 220℃ in a nitrogen atmosphere for 30min. Subsequently, the surface is lightly lubricated with a 0.3% (w / w) food-grade talc aqueous dispersion, and finally wound up to obtain a bend-resistant cable.

[0024] Example 2: A method for preparing a bend-resistant cable for the joints of a robot is as follows: S1: 100g of thermoplastic polyimide was added to a planetary ball mill cooled by liquid nitrogen and ball-milled at 400r / min for 16h. After removal, it was subjected to oxygen plasma treatment at 100W power for 10min. Then it was added to 975g of anhydrous ethanol, along with 5g of perfluorohexylethyltrimethoxysilane and 0.5g of glacial acetic acid. The mixture was stirred at 60℃ for 6h. The mixture was then filtered and the precipitate was washed 4 times with anhydrous ethanol. After that, it was vacuum dried at 120℃ for 12h. Then it was placed in a supercritical carbon dioxide foaming reactor and kept at a pressure of 22MPa and a temperature of 235℃ for 2.5h. Finally, the pressure was rapidly released within 10s to obtain modified porous particles. S2: 15.6 g of 4-amino-2,2,6,6-tetramethylpiperidine and 10.1 g of triethylamine were added to 510 mL of anhydrous dichloromethane. The mixture was then cooled to 0 °C in an ice bath, and 32.8 g of perfluorohexyl ethyl sulfonyl fluoride was added dropwise. The mixture was then heated to 30 °C and reacted for 12 h. After filtration, the solvent was removed by vacuum distillation of the filtrate. The filtrate was then dissolved in 300 mL of anhydrous ethanol. Finally, 11.7 g of sodium chloroacetate and 8 g of sodium hydroxide were added, and the mixture was refluxed at 80 °C for 11 h. After cooling, the pH was adjusted to 2.5 with a 1 mol / L hydrochloric acid aqueous solution. The mixture was then filtered, and the precipitate was washed four times with deionized water. After vacuum drying at 60 °C for 9 h, an anionic fluorinated hindered amine was obtained. S3: Add 15g of magnesium-aluminum layered bimetallic hydroxide nanosheets to 1100mL of deionized water and ultrasonically disperse for 25min. Then add 24.5g of anionic fluorine-containing hindered amine and adjust the pH to 8.5 with 1mol / L sodium hydroxide aqueous solution. Stir at 80℃ for 24h under nitrogen atmosphere. After filtration, wash the precipitate 6 times with deionized water. Finally, vacuum dry at 80℃ for 12h to obtain hindered amine intercalated nanosheets. S4: Add 15.5g of hindered amine intercalated nanosheets to a mixture of 1000mL anhydrous ethanol and 200mL deionized water and ultrasonically disperse for 25min. Then adjust the pH to 9.5 with 25% ammonia water. Add 9g of tetraethyl orthosilicate and stir at 40℃ for 4h. After filtration, wash the precipitate 4 times with anhydrous ethanol. Finally, vacuum dry at 120℃ under nitrogen atmosphere for 12h to obtain the core-shell stabilizer. S5: 950g of ethylene-tetrafluoroethylene copolymer granules, 67.5g of modified porous particles, 14g of core-shell stabilizer, 3.8g of antioxidant 168, and 1.9g of antioxidant 1098 are mixed at 1500r / min for 5min. Then, the mixture is fed into a co-rotating twin-screw extruder and subjected to melt blending extrusion at barrel temperatures of 260℃, 275℃, 285℃, and 290℃, a die temperature of 300℃, and a screw speed of 200r / min. After water cooling and pelletizing, modified ETFE granules are obtained. S6: 19 silver-copper alloy monofilaments (0.03mm in diameter) are twisted together to form a cross-sectional area of ​​0.014mm². 2 Four identical conductors were prepared in total. S7: Arrange the four conductors in parallel and pass them through the center positioning die of a single-screw extruder (L / D ratio 25:1) with a rotating die head. The die ensures that the four conductors maintain a uniform spacing and do not contact each other. Then, add the modified ETFE granules to the extruder, which has a feeding section of 280°C, a melting section of 290°C, and a die head of 300°C. Start the extruder and rotating die head, causing the die head to drive the four conductors forward synchronously at a speed of 15 r / min. Simultaneously, set the traction speed to 3 m / min and control the extrusion draw ratio. 2.0 (ratio of extrusion die cross-sectional area to final insulation cross-sectional area): Molten modified ETFE is extruded through the spiral flow channel of the rotating die head, simultaneously coating the four conductors in a spiral twisting manner to form a uniform and continuous insulation layer (the spiral direction of the insulation layer is opposite to the twisting direction of the conductor filaments), directly obtaining a single four-core cable (cable outer diameter is 1.5mm, average insulation layer thickness is 0.35mm, thinnest point thickness is ≥0.32mm, thickness deviation is ≤±0.03mm, insulation layer concentricity is ≥90%). S8: After heat setting of a single four-core cable at 190℃ for 40s, it is water cooled in a 10℃ water bath for 13s. After drying, it is irradiated with an electron beam dose of 150kGy in a nitrogen atmosphere, and then crosslinked heat treatment is performed at 220℃ in a nitrogen atmosphere for 30min. Subsequently, the surface is lightly lubricated with a 0.3% (w / w) food-grade talc aqueous dispersion, and finally wound up to obtain a bend-resistant cable.

[0025] Example 3: A method for preparing a bend-resistant cable for the joints of a robot is as follows: S1: 100g of thermoplastic polyimide was added to a planetary ball mill cooled by liquid nitrogen and ball-milled at 400r / min for 16h. After removal, it was subjected to oxygen plasma treatment at 100W power for 10min. Then it was added to 1000g of anhydrous ethanol, along with 5g of perfluorohexylethyltrimethoxysilane and 0.5g of glacial acetic acid. The mixture was stirred at 60℃ for 6h. The mixture was then filtered and the precipitate was washed 5 times with anhydrous ethanol. After drying under vacuum at 120℃ for 12h, it was placed in a supercritical carbon dioxide foaming reactor and kept at a pressure of 22MPa and a temperature of 240℃ for 2.5h. Finally, the pressure was rapidly released within 10s to obtain modified porous particles. S2: 15.6 g of 4-amino-2,2,6,6-tetramethylpiperidine and 10.1 g of triethylamine were added to 520 mL of anhydrous dichloromethane. The mixture was then cooled to 0 °C in an ice bath, and 32.8 g of perfluorohexyl ethyl sulfonyl fluoride was added dropwise. The mixture was then heated to 35 °C and reacted for 12 h. After filtration, the solvent was removed by vacuum distillation of the filtrate. The filtrate was then dissolved in 300 mL of anhydrous ethanol. Finally, 11.7 g of sodium chloroacetate and 8 g of sodium hydroxide were added, and the mixture was refluxed at 80 °C for 12 h. After cooling, the pH was adjusted to 3 with a 1 mol / L hydrochloric acid aqueous solution. The mixture was then filtered, and the precipitate was washed 5 times with deionized water. After vacuum drying at 60 °C for 10 h, an anionic fluorinated hindered amine was obtained. S3: Add 15g of magnesium-aluminum layered bimetallic hydroxide nanosheets to 1200mL of deionized water and ultrasonically disperse for 30min. Then add 25g of anionic fluorine-containing hindered amine and adjust the pH to 8.5 with 1mol / L sodium hydroxide aqueous solution. Stir at 80℃ for 24h under nitrogen atmosphere. After filtration, wash the precipitate 7 times with deionized water. Finally, vacuum dry at 80℃ for 12h to obtain hindered amine intercalated nanosheets. S4: Add 16g of hindered amine intercalated nanosheets to a mixture of 1000mL anhydrous ethanol and 200mL deionized water and disperse ultrasonically for 30min. Then adjust the pH to 10 with 25% ammonia water. Add 9g of tetraethyl orthosilicate and stir at 40℃ for 4h. After filtration, wash the precipitate 5 times with anhydrous ethanol. Finally, vacuum dry at 120℃ under nitrogen atmosphere for 12h to obtain the core-shell stabilizer. S5: Mix 1000g of ethylene-tetrafluoroethylene copolymer granules, 70g of modified porous particles, 15g of core-shell stabilizer, 4g of antioxidant 168, and 2g of antioxidant 1098 at 1500r / min for 5min. Then, add the mixture to a co-rotating twin-screw extruder and perform melt blending extrusion at barrel temperatures of 260℃, 275℃, 285℃, and 290℃, a die temperature of 300℃, and a screw speed of 200r / min. After water cooling and pelletizing, the modified ETFE granules are obtained. S6: Twist 20 silver-copper alloy monofilaments (0.03mm in diameter) together to form a cross-sectional area of ​​0.014mm². 2 Four identical conductors were prepared in total. S7: Arrange the four conductors in parallel and pass them through the center positioning die of a single-screw extruder (L / D ratio 25:1) with a rotating die head. The die ensures that the four conductors maintain a uniform spacing and do not contact each other. Then, add the modified ETFE granules to the extruder, which has a feeding section of 280°C, a melting section of 290°C, and a die head of 300°C. Start the extruder and rotating die head, causing the die head to drive the four conductors forward synchronously at a speed of 15 r / min. Simultaneously, set the traction speed to 3 m / min and control the extrusion draw ratio. 2.0 (ratio of extrusion die cross-sectional area to final insulation cross-sectional area): Molten modified ETFE is extruded through the spiral flow channel of the rotating die head, simultaneously coating the four conductors in a spiral twisting manner to form a uniform and continuous insulation layer (the spiral direction of the insulation layer is opposite to the twisting direction of the conductor filaments), directly obtaining a single four-core cable (cable outer diameter is 1.5mm, average insulation layer thickness is 0.35mm, thinnest point thickness is ≥0.32mm, thickness deviation is ≤±0.03mm, insulation layer concentricity is ≥90%). S8: After heat setting of a single four-core cable at 190℃ for 40s, it is water cooled in a 10℃ water bath for 16s. After drying, it is irradiated with an electron beam dose of 150kGy in a nitrogen atmosphere, and then crosslinked heat treatment is performed at 220℃ in a nitrogen atmosphere for 30min. Subsequently, the surface is lightly lubricated with a 0.3% (w / w) food-grade talc aqueous dispersion. Finally, it is wound up to obtain a bend-resistant cable.

[0026] Comparative Example 1: Compared with Example 1, this comparative example only replaces the "modified porous particles" added during the S5 preparation process with "adding 100g of thermoplastic polyimide to a planetary ball mill cooled by liquid nitrogen, ball milling at 400r / min for 16h, and then taking it out to obtain unmodified thermoplastic polyimide". All other steps and parameters are the same, and will not be repeated in this comparative example. Finally, a bend-resistant cable is obtained.

[0027] Comparative Example 2: Compared with Example 1, this comparative example only did not add "modified porous particles" in the preparation process of S5. All other steps and parameters were the same, and will not be repeated here. The final result was a bend-resistant cable.

[0028] Comparative Example 3: Compared with Example 1, this comparative example differs only in that the step in the preparation process of S2, which involves adding 15.6 g of 4-amino-2,2,6,6-tetramethylpiperidine and 10.1 g of triethylamine to 500 mL of anhydrous dichloromethane, cooling to 0°C in an ice bath, adding 32.8 g of perfluorohexyl ethyl sulfonyl fluoride dropwise, heating to 25°C and reacting for 12 h, filtering, removing the solvent by vacuum distillation of the filtrate, dissolving it in 300 mL of anhydrous ethanol, and finally adding 11.7 g of sodium chloroacetate and 8 g of sodium hydroxide and refluxing at 80°C for 10 h, is replaced with "adding 15.6 g of 4-amino-2,2,6,6-tetramethylpiperidine, 11.7 g of sodium chloroacetate and 8 g of sodium hydroxide to 300 mL of anhydrous ethanol and refluxing at 80°C for 10 h". All other steps and parameters are the same, and will not be repeated in this comparative example. The final result is a bend-resistant cable.

[0029] Comparative Example 4: Compared with Example 1, this comparative example only replaces the "core-shell stabilizer" added during the S5 preparation process with "magnesium-aluminum layered bimetallic hydroxide nanosheets". All other steps and parameters are the same, and will not be repeated in this comparative example. Finally, a bend-resistant cable is obtained.

[0030] Comparative Example 5: Compared with Example 1, this comparative example only did not add a "core-shell stabilizer" in the preparation process of S5. All other steps and parameters were the same, and will not be repeated here. The final result was a bend-resistant cable.

[0031] Comparative Example 6: Compared with Example 1, this comparative example only did not use the "rotating die head" in the preparation process of S7 (using ordinary direct extrusion process to cover the insulation layer). All other steps and parameters are the same, and will not be repeated in this comparative example. Finally, a bend-resistant cable was obtained.

[0032] Performance testing: Torsional resistance determination: Referring to the T / SZRCA 011-2025 standard, the 500mm long bend-resistant cables prepared in Examples 1-3 and Comparative Examples 1-6 of this invention were fixed at one end to the fixed clamp of a torsion testing machine, and at the other end to a rotatable clamp (all clamps were padded with soft rubber pads). The distance between the two clamps was 300mm. The number of qualified torsion cycles was measured at 25℃, with a torsion rate of ±360° / m per unit length (actual torsion angle ±108°), a torsion speed of 30 cycles / minute (one round trip is one cycle), the cable maintaining a natural straight state without additional bending, and the loading condition being that four independent conductors were each carrying rated current, with real-time monitoring of conductivity. The qualified torsion cycle was determined (the qualified judgment criteria were: after completing the specified number of cycles, no conductor should have an open circuit or short circuit, and the insulation layer should not have cracks or damage, and the DC resistance change rate of all four conductors should be ≤5%). The test results are shown in Table 1.

[0033] Determination of flexural strength: Referring to the T / SZRCA 002-2024 standard, the 1100mm long bend-resistant cables prepared in Examples 1-3 and Comparative Examples 1-6 of this invention were fixed at one end on a swing tester, and a weight with a total load of 50g (including the weight of the free end of the cable) was suspended at the other end. The number of qualified bends was measured at 25℃, with a swing angle of ±90° (swinging 90° to each side from the vertical position), a swing frequency of 60 times / minute, a bending radius of 2×the outer diameter of the cable, and a loading condition in which four independent conductors were respectively subjected to rated current, and the conductivity was monitored in real time. The qualified bend count was determined (the qualified judgment criteria: after completing the specified number of bends, no conductor should have an open circuit or short circuit, and the insulation layer should not have cracks or damage, and there should be no microsecond-level instantaneous interruption during the test). The test results are shown in Table 1.

[0034] Low temperature resistance test: Referring to the T / SZRCA 002-2024 standard, the 1100mm long bend-resistant cables prepared in Examples 1-3 and Comparative Examples 1-6 of this invention were kept at -60℃ for 4 hours. One end was fixed on a swing tester, and the other end was suspended with a 50g weight. The number of qualified bends was measured at -60℃, with a swing angle of ±90° (swinging 90° to each side from the vertical position), a swing frequency of 60 times / minute, a bending radius of 2 × cable outer diameter, and a loading condition in which four independent conductors were each subjected to rated current. The conductivity was monitored in real time. The qualified bend count was determined (the qualified judgment criteria were: after completing the specified number of bends, no conductor should have an open circuit or short circuit, and the insulation layer should not have cracks or damage. There should be no microsecond-level instantaneous interruption during the test). The test results are shown in Table 1.

[0035] Determination of aging resistance: Referring to GB / T 2951.12-2008 and T / SZRCA 002-2024 standards, the insulation layer of the 100mm long bend-resistant cables prepared in Examples 1-3 and Comparative Examples 1-6 of this invention was stripped to form Type I dumbbell-shaped specimens (gauge length 20mm, width 4mm, thickness equal to the actual thickness of the insulation layer). After aging at 220℃ for 168h, the specimens were placed at room temperature for 16h. The tensile strength (MPa) of the bend-resistant cables before and after aging was measured at a tensile speed of 250mm / min. The test results are shown in Table 1.

[0036] Determination of heat resistance: Referring to GB / T 2951-2008 standard, cylindrical specimens with a diameter of 10 mm and a thickness of 4 mm were prepared on the insulation layer of the bend-resistant cables prepared in Examples 1-3 and Comparative Examples 1-6 of this invention. After applying a load of 0.2 MPa at 220℃ and holding for 1 h, their thermal deformation rate (%) was measured. The measurement results are shown in Table 1.

[0037] Table 1: Performance test results of Examples 1-3 and Comparative Examples 1-6

[0038] Data Analysis: As can be seen from Table 1, the bending-resistant cable for robot joints prepared in the embodiments of the present invention has excellent torsional life, bending life, bending resistance at low temperature, aging resistance and heat resistance.

[0039] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A bend-resistant cable for the joints of a robotic body, characterized in that, The bend-resistant cable includes four conductors and an insulation layer wrapped around the four conductors in a spiral twist. The conductor is made of 18-20 silver-copper alloy monofilaments twisted together. The insulating layer is made of modified ETFE granules; the modified ETFE granules comprise the following raw materials in parts by weight: 900-1000 parts of ethylene-tetrafluoroethylene copolymer granules, 65-70 parts of modified porous particles, 13-15 parts of core-shell stabilizer, and 5.3-6 parts of antioxidant. The modified porous particles are thermoplastic polyimide that is first ball-milled and then surface-treated with oxygen plasma, then grafted with perfluorohexylethyltrimethoxysilane and finally foamed with supercritical carbon dioxide. The core-shell stabilizer is an anionic fluorinated hindered amine prepared by reacting 4-amino-2,2,6,6-tetramethylpiperidine and perfluorohexylethylsulfonyl fluoride. It is then intercalated into the interlayer of magnesium-aluminum layered bimetallic hydroxide nanosheets via an ion exchange reaction, and finally coated with a silica shell by a sol-gel method.

2. The bend-resistant cable for the joints of a robotic body according to claim 1, characterized in that, The modified porous particles are prepared as follows: Thermoplastic polyimide was ball-milled at 400 r / min for 16 h, then subjected to oxygen plasma treatment at 100 W for 10 min. After that, it was added to anhydrous ethanol, along with perfluorohexylethyltrimethoxysilane and glacial acetic acid, and stirred at 60 °C for 6 h. The mixture was then filtered, washed, and dried. Subsequently, it was placed in a supercritical carbon dioxide foaming reactor and maintained at a pressure of 22 MPa and a temperature of 230-240 °C for 2.5 h. Finally, the pressure was released to obtain modified porous particles.

3. The bend-resistant cable for the joints of a robotic body according to claim 2, characterized in that, The mass ratio of the thermoplastic polyimide, anhydrous ethanol, perfluorohexylethyltrimethoxysilane, and glacial acetic acid is 100:950-1000:5:0.

5.

4. The bend-resistant cable for the joints of a robotic body according to claim 1, characterized in that, The preparation method of the core-shell stabilizer is as follows: A1: Add 4-amino-2,2,6,6-tetramethylpiperidine and triethylamine to anhydrous dichloromethane, then cool to 0°C, add perfluorohexylethylsulfonyl fluoride dropwise, then heat to 25-35°C and react for 12 h, filter, remove the solvent by vacuum distillation of the filtrate, then dissolve in anhydrous ethanol, finally add sodium chloroacetate and sodium hydroxide and reflux at 80°C for 10-12 h, cool and adjust the pH to 2-3, then filter, wash the precipitate and dry to obtain anionic fluorinated hindered amine; A2: Add magnesium-aluminum layered bimetallic hydroxide nanosheets to deionized water and ultrasonically disperse for 20-30 min. Then add anionic fluorine-containing hindered amine and adjust the pH to 8.

5. Stir at 80℃ under nitrogen atmosphere for 24 h. After filtration, wash the precipitate and dry it to obtain hindered amine intercalated nanosheets. A3: Add hindered amine intercalated nanosheets to a mixture of anhydrous ethanol and deionized water and disperse ultrasonically for 20-30 min. Then adjust the pH to 9-10, add tetraethyl orthosilicate dropwise and stir at 40℃ for 4 h. After filtration, wash the precipitate and dry it to obtain the core-shell stabilizer.

5. The bend-resistant cable for the joints of a robotic body according to claim 4, characterized in that, The amounts of anhydrous dichloromethane, 4-amino-2,2,6,6-tetramethylpiperidine, triethylamine, perfluorohexylethylsulfonyl fluoride, anhydrous ethanol, sodium chloroacetate, and sodium hydroxide described in A1 are 500-520 mL: 15.6 g: 10.1 g: 32.8 g: 300 mL: 11.7 g: 8 g.

6. The bend-resistant cable for the joints of a robotic body according to claim 4, characterized in that, The ratio of deionized water, magnesium-aluminum layered bimetallic hydroxide nanosheets, and anionic hindered fluorine-containing amines described in A2 is 1000-1200 mL: 15 g: 24-25 g.

7. The bend-resistant cable for the joints of a robot according to claim 4, characterized in that, The ratio of anhydrous ethanol, deionized water, hindered amine intercalated nanosheets, and tetraethyl orthosilicate described in A3 is 1000mL:200mL:15-16g:9g.

8. The bend-resistant cable for the joints of a robotic body according to claim 1, characterized in that, The method for preparing the bend-resistant cable is as follows: S1: Mix ethylene-tetrafluoroethylene copolymer granules, modified porous particles, core-shell stabilizer, and antioxidant, then melt-blend and extrude, followed by water cooling and pelletizing to obtain modified ETFE granules. S2: Twist 18-20 silver-copper alloy monofilaments together to form a conductor, and prepare a total of 4 identical conductors; S3: Four conductors are arranged in parallel and passed through the center positioning mold of a single screw extruder with a rotating head. Modified ETFE granules are then added to the extruder. The extruder and rotating head are then started, causing the head to drive the four conductors to rotate synchronously forward at a speed of 15 r / min. At the same time, the traction speed is set to 3 m / min and the extrusion stretch ratio is controlled to 2.

0. The molten modified ETFE simultaneously coats the four conductors in a spiral twisting manner to form an insulation layer, resulting in a single four-core cable. S4: After heat setting of a single four-core cable at 190℃ for 40s, it is water-cooled, dried, and then irradiated in a nitrogen atmosphere. After cross-linking heat treatment at 220℃ in a nitrogen atmosphere for 30min, the surface is lubricated with talc powder aqueous dispersion and finally wound up to obtain a bend-resistant cable.

9. The bend-resistant cable for the joints of a robotic body according to claim 8, characterized in that, After the four conductors described in S3 pass through the mold, there is a gap between the four conductors and they do not touch each other; The spiral direction of the insulating layer described in S3 is opposite to the twisting direction of the conductor filaments.

10. The bend-resistant cable for the joints of a robotic body according to claim 8, characterized in that, The electron beam irradiation dose during the irradiation treatment described in S4 is 150 kGy; The mass fraction of the talc powder aqueous dispersion in S4 is 0.3%.

Images