Shielding layer composite structure of electromagnetic pulse protection robot cable and preparation method

Abstract

The invention discloses a shielding layer composite structure of an electromagnetic pulse protection robot cable and a preparation method, the shielding layer composite structure comprises a conductor, an insulating layer, a shielding layer and an outer sheath which are sequentially arranged from inside to outside, and the shielding layer is of a composite shielding structure and sequentially comprises an inner conductive layer, an insulating isolation layer and an outer magnetic conductive layer from inside to outside; through the synergistic effect of reflecting an electric field component by the inner conductive layer and absorbing a magnetic field component by the outer magnetic conductive layer, interlayer coupling is inhibited in combination with the insulating isolation layer, the shielding effectiveness is improved, and the absorbing capacity of the magnetic field component is enhanced; the bending life of the cable is prolonged through the 45-degree composite armor layer, the aramid fibers bear more than 90% of mechanical stress, and the tinned copper wires maintain shielding integrity, so that the problem of fatigue fracture of the shielding layer when a robot moves is solved; interlaminar shear stress caused by difference of thermal expansion coefficients is reduced through the ceramic microbead stress buffer layer, compressive strength is improved through the microbead dispersion effect, and structural stability at the extreme temperature is guaranteed.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of robot cable shielding, in particular to a shielding layer composite structure of an electromagnetic pulse protection robot cable and a preparation method. BACKGROUND

[0002] Industrial robot cables are threatened by complex electromagnetic pulses (EMPs) during operation: these pulses are usually generated by nuclear explosions, lightning or high-power equipment switching transients, and the energy of the pulses can be coupled into the robot control system through the cable. The existing electromagnetic pulse (EMP) protection of industrial robot cables mostly adopts a single shielding structure, which has the following limitations: Traditional copper braid or aluminum foil shielding layers only rely on a single reflection mechanism, and have weak absorption capacity for the magnetic field component of EMPs and insufficient shielding effectiveness; During repeated bending motion of the robot, micro-cracks are generated in the rigid metal shielding layer due to stress concentration, and the existing armor layer mostly adopts pure metal wire braiding, which has a short bending life and is prone to a decrease in shielding continuity; Due to the difference in the thermal expansion coefficients of the PVC or PUR outer sheath and the metal shielding layer, delamination is caused by interfacial shear stress when the temperature changes, and the structural stability is insufficient at extreme temperatures; Therefore, it is necessary to design a shielding layer composite structure of an electromagnetic pulse protection robot cable and a preparation method. SUMMARY

[0003] The application aims to provide a shielding layer composite structure of an electromagnetic pulse protection robot cable and a preparation method, to solve the problems of the traditional copper braid or aluminum foil shielding layer only relying on a single reflection mechanism, weak absorption capacity for the magnetic field component of EMPs, insufficient shielding effectiveness, micro-cracks in the rigid metal shielding layer due to stress concentration during repeated bending motion of the robot, short bending life of the existing armor layer mostly adopting pure metal wire braiding, a decrease in shielding continuity, and delamination caused by interfacial shear stress when the temperature changes due to the difference in the thermal expansion coefficients of the PVC or PUR outer sheath and the metal shielding layer, and insufficient structural stability at extreme temperatures.

[0004] To achieve the above-mentioned purpose, the application provides the following technical scheme: In a first aspect, a shielding layer composite structure of an electromagnetic pulse protection robot cable is provided, which comprises a conductor, an insulating layer, a shielding layer and an outer sheath arranged in sequence from inside to outside, the shielding layer is a composite shielding structure, which comprises an inner conductive layer covered by longitudinally overlapped metal foil, an insulating isolation layer composed of a thermoplastic polymer film, and an outer magnetic layer spirally wound by soft magnetic alloy foil, from inside to outside. The inner conductive layer and the outer magnetic conductive layer are physically separated by an insulating isolation layer, the composite shielding structure is designed by physically separating the double layers, the inner conductive layer realizes the reflection of electric field energy, the outer magnetic conductive layer realizes the dissipation of magnetic field eddy current, and the insulating isolation layer blocks the electromagnetic coupling between the layers, forming an EMP protection mechanism for full frequency bands.

[0005] As a further technical solution of the present application, the inner conductive layer is an annealed copper foil, the overlap rate is greater than or equal to 30%, the annealed copper foil improves the ductility to adapt to the bending of the robot, and the overlap rate greater than or equal to 30% ensures the longitudinal electrical continuity and avoids the gap antenna effect.

[0006] As a further technical solution of the present application, the outer magnetic conductive layer is a nickel-iron alloy foil, the relative magnetic permeability is greater than or equal to 5000, the high magnetic permeability nickel-iron alloy is adopted, the low-frequency magnetic field component is absorbed through magnetic domain wall displacement, and the EMP induced current is suppressed.

[0007] As a further technical solution of the present application, an anti-bending armor layer is arranged outside the shielding layer, the anti-bending armor layer is composed of a plated tin copper wire and a aramid fiber composite braid, the braid angle is 45°±5°, the 45° braid angle optimizes the torque balance, the plated tin copper wire provides an auxiliary conductive path, the aramid fiber bears the main mechanical stress, and an electromechanical integrated protection layer is formed.

[0008] As a further technical solution of the present application, the plated tin copper wire and the aramid fiber of the armor layer are alternately braided at a ratio of 1:2, the single filament strength of the aramid fiber is greater than or equal to 20 cN / dtex, the ratio of 1:2 maximizes the tensile strength while ensuring electromagnetic conductivity, and the aramid fiber with a single filament strength greater than or equal to 20 cN / dtex can withstand repeated drag chain movements of the robot.

[0009] As a further technical solution of the present application, a stress buffer layer is arranged between the shielding layer and the outer sheath, the stress buffer layer is composed of a silicone rubber and a ceramic microbead blend, the volume fraction of the ceramic microbead is 10%-15%, the ceramic microbead such as hollow aluminum oxide is dispersed in the silicone rubber matrix as a rigid particle, the micro-strain zone offsets the thermal expansion difference, and the volume fraction of 10%-15% has both buffering property and extrusion process stability.

[0010] In a second aspect, a preparation method of a shielding layer composite structure of an electromagnetic pulse protection robot cable is provided, including the following steps: S1, a metal foil of the inner conductive layer is longitudinally coated outside the insulating layer, a vertical taping machine is used to realize accurate overlap of the copper foil, and the overlap precision is ±0.2 mm; S2, an insulating isolation layer is extruded outside the inner conductive layer, the temperature of the extruder die head is controlled at 200-220℃, and the polytetrafluoroethylene film is gaplessly coated; S3, an alloy foil of the outer magnetic conductive layer is spirally wound outside the insulating isolation layer, the winding tension is less than or equal to 5N, and the plastic deformation of the alloy foil is prevented; S4, braiding an armored layer outside the shielding layer; S5, extruding a stress buffer layer and an outer sheath outside the armored layer, using a double-stage extruder, mixing silicone rubber and microbeads in the first stage, and extruding the sheath at low temperature in the second stage.

[0011] As a further technical solution of the present application, the winding pitch of the alloy foil in step S3 is 1.5-2 times the width of the foil tape, which avoids electromagnetic leakage caused by the spiral gap while ensuring that the layers do not interfere with each other when bending.

[0012] As a further technical solution of the present application, step S4 uses a high-speed braiding machine, and the copper wire and aramid fiber are fed synchronously, which ensures the uniformity of the braided structure, and the matching error of the linear speed is ≤3%.

[0013] As a further technical solution of the present application, the ceramic microbeads in step S5 are hollow alumina microbeads with a particle size distribution of 20-50 μm, and the particle size classification configuration improves the packing density and reduces stress concentration points.

[0014] Compared with the prior art, the electromagnetic pulse protection robot cable shielding layer composite structure and preparation method has the following advantages: Through the synergistic effect of the inner conductive layer reflecting the electric field component and the outer magnetic layer absorbing the magnetic field component, combined with the insulating isolation layer to suppress interlayer coupling, the shielding effectiveness is improved, and the absorption capacity of the magnetic field component is enhanced; Through the 45° composite armored layer, the bending life of the cable is improved, the aramid fiber bears more than 90% of the mechanical stress, and the tin-plated copper wire maintains the shielding integrity, solving the problem of fatigue fracture of the shielding layer during robot movement; Through the ceramic microbead stress buffer layer, the interlayer shear stress caused by the difference in thermal expansion coefficient is reduced, and the dispersion effect of the microbeads improves the compressive strength, ensuring the structural stability at extreme temperatures. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 The figure is a schematic diagram of the overall structure of the present application; Figure 2 The figure is a schematic diagram of the method flow of the present application; In the figure: 1, conductor; 2, insulating layer; 3, shielding layer; 31, inner conductive layer; 32, insulating isolation layer; 33, outer magnetic layer; 4, outer sheath; 5, armored layer; 6, buffer layer. DETAILED DESCRIPTION

[0016] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0017] Please refer to the drawings Figure 1 The present application provides an embodiment of a shielding layer composite structure of an electromagnetic pulse protection robot cable, which comprises a conductor 1, an insulating layer 2, a shielding layer 3 and an outer sheath 4 arranged in sequence from inside to outside, and the shielding layer 3 is a composite shielding structure, which comprises an inner conductive layer 31 covered by longitudinally overlapped metal foil, an insulating isolation layer 32 composed of thermoplastic polymer film and an outer magnetic layer 33 spirally wound by soft magnetic alloy foil in sequence from inside to outside. The inner conductive layer 31 is annealed copper foil, the overlap rate is greater than or equal to 30%, the annealed copper foil improves ductility to adapt to the bending of the robot, and the overlap rate greater than or equal to 30% ensures the longitudinal electrical continuity and avoids the slot antenna effect. The outer magnetic layer 33 is iron-nickel alloy foil, the relative magnetic permeability is greater than or equal to 5000, the high magnetic permeability iron-nickel alloy is adopted to absorb low-frequency magnetic field components through magnetic domain wall displacement, and the EMP induced current is inhibited. The inner conductive layer 31 and the outer magnetic layer 33 are physically separated by the insulating isolation layer 32. The composite shielding structure is designed by physical separation of double layers and functions. The inner conductive layer 31 realizes electric field energy reflection, the outer magnetic layer 33 realizes magnetic field eddy current dissipation, the insulating isolation layer 32 blocks electromagnetic coupling between layers, and a full-band EMP protection mechanism is formed. An anti-bending armor layer 5 is arranged on the outer side of the shielding layer 3. The anti-bending armor layer 5 is composed of plated tin copper wire and aramid fiber composite braid, the braid angle is 45°±5°, the 45° braid angle optimizes the torque balance, the plated tin copper wire provides an auxiliary conductive path, the aramid fiber bears the main mechanical stress, and an electromechanical integrated protection layer is formed. The plated tin copper wire and the aramid fiber of the armor layer 5 are alternately braided at a ratio of 1:2, the aramid fiber single filament strength is greater than or equal to 20 cN / dtex, the ratio of 1:2 maximizes the tensile strength while ensuring electromagnetic conductivity, and the aramid fiber with a strength greater than or equal to 20 cN / dtex can withstand repeated drag chain movements of the robot. A stress buffer layer 6 is arranged between the shielding layer 3 and the outer sheath 4. The stress buffer layer 6 is composed of a silicon rubber and ceramic microbead blend, and the volume fraction of the ceramic microbead is 10%-15%. The ceramic microbead such as hollow alumina is dispersed in the silicon rubber matrix as a rigid particle, the micro-strain zone offsets the thermal expansion difference, and the volume fraction of 10%-15% has both buffering property and extrusion process stability.

[0018] Please refer to the drawings Figure 2 The present application provides an embodiment of a preparation method of a shielding layer composite structure of an electromagnetic pulse protection robot cable, which comprises the following steps: S1, longitudinally cladding the inner conductive layer 31 metal foil outside the insulating layer 2, using a vertical tape wrapping machine to realize accurate lap joint of copper foil, the lap joint accuracy is ±0.2mm; S2, extruding the insulating isolation layer 32 outside the inner conductive layer 31, the temperature of the extruder die head is controlled at 200-220℃, so that the polytetrafluoroethylene FEP film is gap-free cladding; S3, spirally winding the outer magnetic layer 33 alloy foil outside the insulating isolation layer 32, the winding tension is ≤5N, preventing plastic deformation of the alloy foil, and the winding pitch of the alloy foil is 1.5-2 times the width of the foil tape, which avoids electromagnetic leakage caused by spiral gap, and ensures that there is no interference between layers when bending; S4, braiding the armored layer 5 outside the shielding layer 3, using a high-speed braiding machine, the copper wire and aramid fiber are synchronously fed, synchronous feeding ensures the uniformity of the braided structure, and the matching error of linear velocity is ≤3%; S5, extruding the stress buffer layer 6 and the outer protective sleeve 4 outside the armored layer 5, using a double-stage extruder, mixing silicone rubber and microbeads in the first stage, and extruding the protective sleeve at low temperature in the second stage, the ceramic microbeads are hollow alumina microbeads with a particle size distribution of 20-50μm, and the particle size classification configuration improves the packing density and reduces stress concentration points.

[0019] In summary, through the synergistic effect of the inner conductive layer 31 reflecting the electric field component and the outer magnetic layer 33 absorbing the magnetic field component, combined with the insulating isolation layer 32 inhibiting interlayer coupling, the shielding effectiveness is improved, and the absorption capacity of the magnetic field component is enhanced; Through the 45° composite armored layer 5, the bending life of the cable is improved, the aramid fiber bears more than 90% mechanical stress, and the tin-plated copper wire maintains the shielding integrity, solving the problem of fatigue fracture of the shielding layer 3 when the robot moves; Through the ceramic microbead stress buffer layer 6, the interlayer shear stress caused by the difference in thermal expansion coefficient is reduced, and the microbead dispersion effect improves the compressive strength, ensuring the structural stability at extreme temperatures.

[0020] It is apparent for those skilled in the art that the present application is not limited to the details of the above-described exemplary embodiments, but can be implemented in other concrete forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be considered in all respects as illustrative and not restrictive, the scope of the present application being defined by the appended claims rather than the above description, and it is intended to embrace all changes and modifications that fall within the meaning and scope of the equivalent elements of the claims. Any reference signs in the claims should not be considered as limiting the claims involved.

Claims

1. A composite shielding structure for an electromagnetic pulse-protected robot cable, comprising a conductor (1), an insulation layer (2), a shielding layer (3), and an outer sheath (4) arranged sequentially from the inside out, characterized in that: The shielding layer (3) is a composite shielding structure, which includes, from the inside out: an inner conductive layer (31) covered by longitudinally overlapping metal foil, an insulating isolation layer (32) made of thermoplastic polymer film, and an outer magnetic conductive layer (33) spirally wound with soft magnetic alloy foil. The inner conductive layer (31) and the outer magnetic layer (33) are physically separated by an insulating isolation layer (32).

2. The composite shielding structure of the electromagnetic pulse protected robot cable according to claim 1, characterized in that: The inner conductive layer (31) is an annealed copper foil with an overlap rate of ≥30%.

3. The composite shielding structure of the electromagnetic pulse protected robot cable according to claim 1, characterized in that: The outer magnetic layer (33) is an iron-nickel alloy foil with a relative permeability ≥5000.

4. The composite shielding structure of the electromagnetic pulse protected robot cable according to claim 1, characterized in that: The shielding layer (3) is provided with an anti-bending armor layer (5) on the outside. The anti-bending armor layer (5) is composed of tin-plated copper wire and aramid fiber composite weaving, with a weaving angle of 45°±5°.

5. The composite shielding structure of the electromagnetic pulse protected robot cable according to claim 4, characterized in that: The tin-plated copper wire and aramid fiber of the armor layer (5) are woven alternately in a 1:2 ratio, and the aramid fiber monofilament strength is ≥20cN / dtex.

6. The composite shielding structure of the electromagnetic pulse protected robot cable according to claim 1, characterized in that: A stress buffer layer (6) is provided between the shielding layer (3) and the outer sheath (4). The stress buffer layer (6) is composed of a blend of silicone rubber and ceramic microspheres, with the ceramic microspheres accounting for 10%-15% of the volume.

7. A method for preparing a composite shielding structure for an electromagnetic pulse protected robot cable, characterized in that: Includes the following steps: S1. A metal foil with an inner conductive layer (31) is longitudinally wrapped around the outside of the insulating layer (2); S2. An insulating isolation layer (32) is formed by extrusion outside the inner conductive layer (31); S3. The outer magnetic layer (33) alloy foil is spirally wound around the outer insulating layer (32); S4. Weave an armor layer (5) outside the shielding layer (3); S5. An extruded stress buffer layer (6) and an outer sheath (4) are placed outside the armor layer (5).

8. The method for preparing the shielding layer composite structure of the electromagnetic pulse protected robot cable according to claim 7, characterized in that: In step S3, the alloy foil winding pitch is 1.5-2 times the foil width.

9. The method for preparing the shielding layer composite structure of the electromagnetic pulse protected robot cable according to claim 7, characterized in that: Step S4 uses a high-speed braiding machine, where copper wire and aramid fiber are fed in simultaneously.

10. The method for preparing the shielding layer composite structure of the electromagnetic pulse protected robot cable according to claim 7, characterized in that: In step S5, the ceramic microspheres are hollow alumina microspheres with a particle size distribution of 20-50 μm.

Images