Double-helix carbon nanotube enhanced lightweight robot cable and preparation method thereof

Abstract

The invention discloses a double-helix carbon nanotube enhanced lightweight robot cable and a preparation method thereof. The double-helix carbon nanotube enhanced lightweight robot cable comprises a conductive core wire, a first enhancement layer, a second enhancement layer and an insulating coating layer which are sequentially arranged from inside to outside, according to the invention, through a double-helix reverse winding structure, a concave-convex structure and resin permeation, the tensile strength and the anti-torsion angle are improved while the flexibility of the cable is maintained, and the problem of cable breakage in joint movement of a robot is solved; the interface bonding strength of the carbon nanotubes and resin is improved through plasma etching and the polydopamine bonding layer, the bending life is prolonged by combining the stress release design of the corrugated insulating layer, and reliable guarantee is provided for continuous operation of an industrial robot; on the basis of a metal reinforced cable, the weight is reduced, the silver-plated nylon shielding layer provides effective electromagnetic shielding effectiveness, the thermoplastic polyurethane material provides enough tolerance, and the requirements of high-end fields such as automobiles and aerospace for light-weight and high-reliability robot cables are met.

Description

Technical Field

[0001] This invention relates to the field of robot cable technology, specifically to a double-helix carbon nanotube reinforced lightweight robot cable and its preparation method. Background Technology

[0002] Existing robot cables generally use a unidirectional spiral metal wire reinforcement layer, made of stainless steel or copper alloy. Although this can improve tensile strength, it increases the weight of the cable by 35%-40%, which severely restricts the acceleration response of the robot joint. More importantly, the single spiral structure generates stress concentration under forward and reverse torsion conditions. When the torsion angle is too large, it is very easy to cause permanent deformation or even core breakage. Although carbon fiber reinforced cables reduce weight, the smooth and chemically inert surface of carbon fibers results in weak bonding with the resin matrix. During high-frequency bending by a robot, interfacial microcracks propagate along the direction of the reinforcing fibers, eventually leading to interlayer delamination failure. Existing surface treatment technologies, such as nitric acid oxidation, can only create micron-level roughness and cannot achieve nanoscale mechanical interlocking. Traditional lightweight solutions often sacrifice other properties in pursuit of flexibility: the non-corrugated structure of the polyurethane insulation layer is prone to wrinkling and cracking when the bending radius is small; the metal braided shielding layer adds up to 25% in weight and has weak electromagnetic shielding effectiveness; and the temperature resistance range is narrow, which cannot meet the needs of high-temperature scenarios such as automotive welding robots. Therefore, it is essential to design and fabricate a double-helix carbon nanotube-reinforced lightweight robot cable. Summary of the Invention

[0003] The purpose of this invention is to provide a double-helix carbon nanotube-reinforced lightweight robot cable and its preparation method. This addresses the problems of existing robot cables that commonly use unidirectional helical metal wire reinforcement layers made of stainless steel or copper alloys. While this improves tensile strength, it increases cable weight by 35%-40%, severely restricting the acceleration response of robot joints. More importantly, the single helical structure generates stress concentration under forward and reverse torsion conditions, easily leading to permanent deformation or even core breakage when the torsion angle is too large. While carbon fiber reinforced cables reduce weight, the smooth and chemically inert surface of carbon fibers results in weak bonding with the resin matrix. During high-frequency bending of the robot, interfacial microcracks propagate along the reinforcing fiber direction, ultimately leading to interlayer delamination failure. Existing surface treatment technologies, such as nitric acid oxidation, can only create micron-level roughness, failing to achieve nanometer-level mechanical interlocking. Furthermore, traditional lightweight solutions often sacrifice other properties in pursuit of flexibility: the non-corrugated polyurethane insulation layer is prone to wrinkling and cracking at small bending radii; the metal braided shielding layer increases weight by up to 25% and has weak electromagnetic shielding effectiveness; and the narrow temperature range fails to meet the requirements of high-temperature scenarios such as automotive welding robots.

[0004] To achieve the above objectives, the present invention provides the following technical solution: In one aspect, a double-helix carbon nanotube-reinforced lightweight robot cable is provided, comprising a conductive core wire, a first reinforcing layer, a second reinforcing layer and an insulating covering layer arranged sequentially from the inside out. The first reinforcing layer is composed of surface-functionalized carbon nanotubes wound around the conductive core wire in a left-handed helical manner, and the second reinforcing layer is composed of surface-functionalized carbon nanotubes wound around the first reinforcing layer in a right-handed helical manner. The double helixes are wound in opposite directions to form a self-balancing structure to counteract the torsional stresses of the robot joints in both directions. The insulating coating layer is wrapped around the second reinforcing layer to form an insulating protection for the second reinforcing layer; The surface functionalization treatment of the carbon nanotubes gives them an uneven structure, which enhances the interfacial mechanical bonding strength and inhibits interlayer slippage.

[0005] As a further technical solution of the present invention, the helix angle of the first reinforcing layer and the second reinforcing layer are both 25°–35°, and the winding density is both 60–80 bundles / cm. The parameter range is used to optimize stress distribution and take into account both flexible bending and tensile strength.

[0006] As a further technical solution of the present invention, the surface of the carbon nanotube bundle is formed into a nanoscale uneven structure by plasma etching treatment, and the surface of the uneven structure is covered with a polydopamine adhesive layer. The polydopamine layer enhances the wettability of the resin and realizes molecular-level interface bonding.

[0007] As a further technical solution of the present invention, a thermosetting epoxy resin transition layer is provided between the first reinforcing layer and the second reinforcing layer, the transition layer penetrating into the interior of the carbon nanotube bundle to block the crack propagation path.

[0008] As a further technical solution of the present invention, the insulating coating layer is a thermoplastic polyurethane material, and its outer surface is provided with an anti-torsion corrugated structure. The corrugated structure design matches the mechanical response of the spiral layer to prevent fatigue cracking of the insulating layer.

[0009] As a further technical solution of the present invention, a silver-plated nylon fiber braided shielding layer is disposed between the second reinforcing layer and the insulating covering layer to improve the cable shielding performance.

[0010] As a further technical solution of the present invention, the diameter of the single filament of the carbon nanotube bundle is 0.8–1.2 μm, and the depth of the nanoscale uneven structure is 50–100 nm, thereby improving the interfacial bonding energy.

[0011] Secondly, a method for preparing a double-helix carbon nanotube-reinforced lightweight robotic cable is provided, including: 1) Perform plasma etching on carbon nanotube bundles under an argon atmosphere at a power of 200–400W for 5–15 minutes; 2) Immerse the etched carbon nanotube bundles in a polydopamine solution with a concentration of 2–5 mg / mL, pH 8.5, for 30–60 min. 3) The first reinforcing layer is wound around the conductive core wire in a left-hand spiral manner; 4) Apply epoxy resin to form a transition layer; 5) Wrap the second reinforcing layer around the transition layer in a right-handed spiral; 6) Cover with a shielding layer and an insulating layer and then cure and shape.

[0012] As a further technical solution of the present invention, the left-hand and right-hand winding process adopts constant tension control to ensure that the spiral layer is uniform and dense.

[0013] As a further technical solution of the present invention, the epoxy resin transition layer is cured under heating and pressurization conditions, and the radial pressure causes the resin to penetrate into the carbon nanotube bundle.

[0014] Compared with existing technologies, the beneficial effects of this double-helix carbon nanotube-reinforced lightweight robotic cable and its preparation method are: By employing a double-helix reverse winding structure, along with the synergistic effect of nanoscale interface anchoring formed by the concave-convex structure and resin infiltration, the cable's tensile strength and torsional angle are improved while maintaining its flexibility, thus solving the problem of cable breakage during robot joint movement. Plasma etching and polydopamine adhesive layer improve the bonding strength between carbon nanotubes and resin interface. Combined with the stress relief design of the corrugated insulation layer, the bending life is extended, providing a reliable guarantee for the continuous operation of industrial robots. Compared to metal-reinforced cables, this cable achieves weight reduction, with a silver-plated nylon shielding layer providing effective electromagnetic shielding and thermoplastic polyurethane material offering sufficient durability, meeting the needs of high-end fields such as automotive and aerospace for lightweight and highly reliable robot cables. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 for Figure 1 Enlarged view of the local structure of region A in the middle; Figure 3 This is a schematic diagram of the method flow of the present invention; In the diagram: 1. Conductive core wire; 2. First reinforcing layer; 3. Second reinforcing layer; 4. Insulating covering layer; 5. Transition layer; 6. Shielding layer. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] Please see the appendix Figure 1 An embodiment of the present invention provides a double-helix carbon nanotube reinforced lightweight robot cable, comprising a conductive core wire 1, a first reinforcing layer 2, a second reinforcing layer 3, and an insulating covering layer 4 arranged sequentially from the inside out. The first reinforcing layer 2 is composed of surface-functionalized carbon nanotubes wound in a left-handed helical manner around the conductive core wire 1, and the second reinforcing layer 3 is composed of surface-functionalized carbon nanotubes wound in a right-handed helical manner around the first reinforcing layer 2. The double helix reverse winding forms a self-balancing structure to counteract the torsional stress of the robot joint in both directions. The helix angle of the first reinforcing layer 2 and the second reinforcing layer 3 are both 25°–35°, and the winding density is both 60–80 bundles / cm. The parameter range is used to optimize stress distribution and take into account both flexible bending and tensile strength. Please see the appendix Figure 2 A thermosetting epoxy resin transition layer 5 is provided between the first reinforcing layer 2 and the second reinforcing layer 3. The transition layer 5 penetrates into the interior of the carbon nanotube bundle, blocking the crack propagation path. The surface functionalization treatment of the carbon nanotubes gives it an uneven structure. The uneven structure improves the interfacial mechanical interlocking strength and inhibits interlayer slippage. The surface of the carbon nanotube bundle is formed by plasma etching to form a nanoscale uneven structure. The surface of the uneven structure is covered with a polydopamine adhesive layer. The polydopamine layer enhances the resin wettability and achieves molecular-level interfacial bonding. The diameter of the single filament of the carbon nanotube bundle is 0.8–1.2 μm, and the depth of the nanoscale uneven structure is 50–100 nm, which improves the interfacial bonding energy. The insulating covering layer 4 is wrapped around the second reinforcing layer 3 to form an insulating protection for the second reinforcing layer 3. The insulating covering layer 4 is made of thermoplastic polyurethane material, and its outer surface is provided with an anti-torsion corrugated structure. The corrugated structure design matches the mechanical response of the spiral layer to prevent fatigue cracking of the insulation layer. It also includes a silver-plated nylon fiber braided shielding layer 6 disposed between the second reinforcing layer 3 and the insulating covering layer 4 to improve the shielding performance of the cable.

[0018] Please see the appendix Figure 3 One embodiment of the present invention provides a method for preparing a double-helix carbon nanotube-reinforced lightweight robot cable, comprising: 1) Perform plasma etching on carbon nanotube bundles under an argon atmosphere at a power of 200–400W for 5–15 minutes; 2) Immerse the etched carbon nanotube bundles in a polydopamine solution with a concentration of 2–5 mg / mL, pH 8.5, for 30–60 min. 3) The first reinforcing layer 2 is wound around the conductive core wire 1 in a left-hand spiral manner; 4) Apply epoxy resin to form a transition layer 5; 5) The second reinforcing layer 3 is wound around the transition layer 5 in a right-handed manner; 6) Cover the shielding layer 6 and the insulating covering layer 4 and cure them into shape; The left-hand and right-hand winding process is controlled by constant tension to ensure that the spiral layer is uniform and dense. The epoxy resin transition layer 5 is cured under heating and pressure, and the radial pressure causes the resin to penetrate into the carbon nanotube bundle.

[0019] In summary, by using a double-helix reverse winding structure, as well as the synergistic effect of nanoscale interface anchoring formed by the concave-convex structure and resin infiltration, the cable flexibility is maintained while the tensile strength and torsional angle are improved, thus solving the problem of cable breakage during robot joint movement. Plasma etching and polydopamine adhesive layer improve the bonding strength between carbon nanotubes and resin interface. Combined with the stress relief design of the corrugated insulation layer, the bending life is extended, providing a reliable guarantee for the continuous operation of industrial robots. Compared to metal-reinforced cables, this cable achieves weight reduction. The silver-plated nylon shielding layer 6 provides effective electromagnetic shielding, while the thermoplastic polyurethane material provides sufficient durability, meeting the needs of high-end fields such as automotive and aerospace for lightweight and highly reliable robot cables.

[0020] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A double-helix carbon nanotube reinforced lightweight robot cable, comprising a conductive core wire (1), a first reinforcing layer (2), a second reinforcing layer (3), and an insulating sheath layer (4) arranged sequentially from the inside out, characterized in that: The first reinforcing layer (2) is a surface-functionalized carbon nanotube wound around the conductive core wire (1) in a left-handed spiral manner, and the second reinforcing layer (3) is a surface-functionalized carbon nanotube wound around the first reinforcing layer (2) in a right-handed spiral manner. The insulating covering layer (4) is wrapped around the second reinforcing layer (3); The surface functionalization treatment of the carbon nanotubes is to give its surface an uneven structure.

2. The double-helix carbon nanotube-reinforced lightweight robot cable according to claim 1, characterized in that: The first reinforcing layer (2) and the second reinforcing layer (3) both have a helix angle of 25°–35° and a winding density of 60–80 bundles / cm.

3. The double-helix carbon nanotube-reinforced lightweight robot cable according to claim 1, characterized in that: The surface of the carbon nanotube bundle is formed into a nanoscale uneven structure through plasma etching, and the surface of the uneven structure is covered with a polydopamine adhesive layer.

4. The double-helix carbon nanotube-reinforced lightweight robot cable according to claim 1, characterized in that: A thermosetting epoxy resin transition layer (5) is provided between the first reinforcing layer (2) and the second reinforcing layer (3), and the transition layer (5) penetrates into the interior of the carbon nanotube bundle.

5. The double-helix carbon nanotube-reinforced lightweight robot cable according to claim 1, characterized in that: The insulating covering layer (4) is made of thermoplastic polyurethane material, and its outer surface is provided with an anti-torsion corrugated structure.

6. The double-helix carbon nanotube-reinforced lightweight robot cable according to claim 1, characterized in that: It also includes a silver-plated nylon fiber braided shielding layer (6) disposed between the second reinforcing layer (3) and the insulating covering layer (4).

7. The double-helix carbon nanotube-reinforced lightweight robot cable according to claim 1, characterized in that: The carbon nanotube bundles have a single filament diameter of 0.8–1.2 μm and a depth of 50–100 nm for their nanoscale uneven structure.

8. A method for preparing a double-helix carbon nanotube-reinforced lightweight robot cable, characterized in that: include: 1) Plasma etching treatment of carbon nanotube bundles; 2) The etched carbon nanotube bundles are impregnated with a polydopamine solution; 3) The first reinforcing layer (2) is wound around the conductive core wire (1) in a left-handed manner; 4) Apply epoxy resin to form a transition layer (5); 5) Wrap the second reinforcing layer (3) around the transition layer (5) in a right-handed manner; 6) Cover the shielding layer (6) and the insulating layer (4) and cure them.

9. The method for preparing the double-helix carbon nanotube-reinforced lightweight robot cable according to claim 8, characterized in that: The left-hand and right-hand winding process is controlled by constant tension.

10. The method for preparing the double-helix carbon nanotube-reinforced lightweight robot cable according to claim 8, characterized in that: The epoxy resin transition layer (5) is cured under heating and pressure conditions.

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