CN112820468A - Low-noise high-shielding fA-level current signal cable for radiation environment and manufacturing process - Google Patents

Abstract

The invention provides a low-noise high-shielding fA-level current signal cable for a radiation environment and a manufacturing process thereof, wherein the cable comprises: an inner conductor disposed in the center of the cable; the wave-absorbing cable comprises a wrapping insulating layer, a wrapping semi-conducting layer, an outer conductor, an inner sheath, an outer shielding layer, a wave-absorbing functional layer and an outer sheath which are sequentially coated on the outer layer of the inner conductor. The cable according to the technical scheme has excellent strength, tensile strength and ideal flexibility, can meet the requirements of low noise, high shielding, high temperature resistance, good flame retardance, irradiation resistance and the like of the radiation environment requirement, and is suitable for stable and high-precision transmission of fA-level weak current signals.

Description

Low-noise high-shielding fA-level current signal cable for radiation environment and manufacturing process

Technical Field

The invention belongs to the technical field of signal transmission cables, and particularly relates to an fA-level current signal cable which is low in noise, high in shielding, high-temperature resistant, radiation resistant and suitable for a radiation environment and a manufacturing process thereof.

Background

The weak signal measurement and control technology plays an increasingly important role in high-sensitivity sensors, high-gain amplifiers and other equipment. The cable used as the connecting device can generate weak signals in the using process, the weak signals can form system noise, and the noise can enable the patterns or maps of the weak signals to be changed, so that the weak signals cannot be detected, are inaccurate to be detected or generate wrong signals. The influence of noise reduction or environmental factors on the cable is reduced, and the precision of the measurement and control technology can be improved undoubtedly. With the development of radiation detection components towards smaller and more sensitive targets, a weak signal stable transmission cable is increasingly required, and considering that a signal cable is applied in a radiation field, the cable must have the functions of low noise, high shielding, high temperature resistance, good flame retardance, radiation resistance and the like. At present, when a cable transmits an fA level current signal, due to reasons of overlarge noise, quick loss on a transmission path and the like, and the influence of a radiation environment on the signal, the measurement and control precision of a weak signal needs to be enhanced urgently, and the development of a signal cable for a low-noise high-shielding radiation environment is very challenging.

The technical solutions of the low-noise cable disclosed in the published chinese patent mainly include the following: the high-temperature low-noise cable disclosed in patent CN204857234U includes a conductor twisted by a single or multiple silver-plated copper wires, an insulating layer extruded outside the conductor and made of PTFE (or FEP, ETFE, PFA), a high-temperature resistant semi-conducting layer located outside the insulating layer, a braided shield layer braided by silver-plated copper wires and arranged outside the high-temperature resistant semi-conducting layer, and a polytetrafluoroethylene outer sheath extruded outside the braided shield layer. The 'low-noise cable' disclosed in patent CN202677957U sequentially comprises an inner conductor, a first semi-conductive graphite layer, a polyethylene insulating layer, a second semi-conductive graphite layer, a tinned copper wire braid layer and a polyurethane outer sheath from inside to outside. The patent CN109473221A discloses a "low-noise phase-stable coaxial cable" which comprises, from inside to outside, an inner conductor, a semiconductor layer, a combined insulating layer, a silver-plated flat copper strip, a woven silver-plated flat wire and a sheath in sequence, wherein the semiconductor layer comprises a substrate, a graphite powder layer coated on the surface of the substrate, and a conductive polymer layer coated outside the graphite powder layer. The 'low-noise cable' disclosed in patent CN109841302A includes a conductor, and an insulating layer, a semi-conducting layer, a slant covering layer, a wrapping layer and an outer sheath which are sequentially located outside the conductor, wherein the conductor is a stranded conductor formed by stranding silver-copper alloy wires around a central reinforcing filler fiber, the insulating layer is polyethylene or fluoroplastic, and a lubricating layer is disposed outside the conductor, wherein the semi-conducting layer is in close contact with the insulating layer.

The technical scheme and other prior art have the following problems: first, strength and flexibility cannot be considered, the inner conductors of patents CN204857234U and CN202677957U are formed by twisting silver-plated and tin-plated copper wires, respectively, and the flexibility can meet the normal use requirement in the twisting and bending process, but the strength is relatively weak. The inner conductor of patent CN109473221A is made of a single silver-plated copper conductor, so that the strength meets the basic requirement, but the flexibility is insufficient. Secondly, since the coefficient of friction of the conductor surface is large, the matching with the insulating layer coated outside is affected to some extent, and thus the desired degree of 1/500, which is the original value of the mechanical noise, is not satisfied. Finally, the above cables have poor radiation resistance in a strong radiation environment, and cannot meet the requirements of radiation resistance, high temperature resistance and aging resistance. In summary, the conventional cable design, material selection and manufacturing process cannot meet the requirements of low-noise and high-shielding fA-level signal cables in a radiation environment, which severely restricts the technical development of the application field, and a stable transmission cable suitable for a radiation environment and capable of low-noise and high-shielding fA-level weak current signals needs to be designed urgently.

Disclosure of Invention

In order to overcome the technical defects that the existing low-noise fA-level cable has overlarge noise, high loss on a transmission path and does not meet the strong radiation condition, the invention provides the low-noise high-shielding fA-level current signal cable for the radiation environment and the manufacturing process thereof, which can meet the requirements of the strong radiation environment, have excellent performances of low noise, high shielding, high temperature resistance, irradiation resistance and the like, and can ensure the stable and reliable transmission of fA-level weak current signals under the conditions of complicated electromagnetic and nuclear radiation disturbance. The cable can be widely applied to the fields of signal transmission in the field of nuclear radiation detection, weak signal transmission in the field of communication, signal transmission of high-precision laboratory instruments and the like, and has high popularization and use values.

In order to solve the above technical problem, the present invention provides a low-noise high-shielding fA-level current signal cable for a radiation environment, the cable comprising:

an inner conductor disposed in the center of the cable;

the wave-absorbing cable comprises a wrapping insulating layer, a wrapping semi-conducting layer, an outer conductor, an inner sheath, an outer shielding layer, a wave-absorbing functional layer and an outer sheath which are sequentially coated on the outer layer of the inner conductor.

The inner conductor is formed by stranding a plurality of silver-plated copper wires around a central reinforcing filling fiber.

The lapping insulating layer is composed of a cross-linked polytetrafluoroethylene film.

The lapped semi-conducting layer is composed of a polytetrafluoroethylene film or a cross-linked polytetrafluoroethylene film.

The outer conductor is composed of a copper wire braided shielding layer which is wrapped outside the wrapping semi-conducting layer.

Wherein, the inner sheath comprises fluoroplastics.

The outer shielding layer is a shielding structure woven by silver-plated copper wires.

The wave-absorbing functional layer is obtained by coating conductive adhesive and adding a wave-absorbing ferrite coating film on the outer shielding layer.

Wherein the outer sheath is comprised of high density polyethylene.

The invention also provides a manufacturing process of the low-noise high-shielding fA-level current signal cable for the radiation environment, which comprises the following steps of:

step S1, stranding a plurality of silver-plated copper wires around the center reinforced filling fiber to form an inner conductor, and arranging the inner conductor at the center of the cable;

step S2, weaving the outer layer of the inner conductor by using a cross-linked polytetrafluoroethylene film in a wrapping mode to obtain a wrapping insulating layer wrapping the outer layer of the inner conductor;

step S3, weaving the outer layer of the wrapped insulating layer by using a semi-conductive cross-linked polytetrafluoroethylene or polytetrafluoroethylene film in a wrapping mode to obtain a wrapped semi-conductive layer coated on the outer layer of the wrapped insulating layer;

step S4, weaving copper wires to obtain a shielding layer, and coating the shielding layer on the outer layer of the wrapped semi-conductive layer to obtain an outer conductor;

step S5, preparing an inner sheath on the outer layer of the outer conductor by using fluoroplastic;

step S6, weaving silver-plated copper wires on the outer layer of the inner sheath to obtain an outer shielding layer;

step S7, weaving the outer layer of the outer shielding layer by using conductive adhesive and a wave-absorbing ferrite film in a wrapping mode to obtain a wave-absorbing functional layer;

and step S8, preparing an outer sheath on the outer layer of the wave-absorbing functional layer by using high-density polyethylene.

The technical effect of the technical scheme provided by the invention is as follows: 1) the inner conductor adopts a stranded conductor formed by stranding silver-copper alloy foil wires around a center reinforcing filling fiber, so that the cable has better strength, tensile strength and ideal flexibility, and can be ensured to be normally used in the twisting and bending process; 2) the wrapping insulating layer is composed of a cross-linked polytetrafluoroethylene film, and the insulating layer is high in strength, good in aging resistance, high in high temperature resistance and high in irradiation resistance by weaving in a wrapping mode, so that the dielectric constant stability of the material is ensured, and the output capacity of signals is improved; 3) the outer shielding layer adopts a silver-plated copper wire braided shielding structure, and the outer shielding layer is coated with conductive adhesive and is added with a wave-absorbing coating in a thin film mode to play a role in signal isolation and electromagnetic interference resistance. The shielding effectiveness and the soft characteristic of the cable are combined, the weaving density of the low-noise cable is controlled to be more than or equal to 90 percent, so that the number of interference electromagnetic waves is reduced, and the overall electromagnetic environment of the system is optimized.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.

Drawings

Other features, objects, and advantages of the present disclosure will become more apparent from the following detailed description of non-limiting embodiments when taken in conjunction with the accompanying drawings. In the drawings:

fig. 1 is a schematic structural diagram of a low-noise high-shielding fA-class current signal cable for a radiation environment according to an embodiment of the invention;

fig. 2 is a schematic flow chart of a manufacturing process of a low-noise high-shielding fA-class current signal cable for a radiation environment according to an embodiment of the invention.

Detailed Description

Hereinafter, exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement them. Also, for the sake of clarity, parts not relevant to the description of the exemplary embodiments are omitted in the drawings.

In the present disclosure, it is to be understood that terms such as "including" or "having," etc., are intended to indicate the presence of the disclosed features, numbers, steps, behaviors, components, parts, or combinations thereof, and are not intended to preclude the possibility that one or more other features, numbers, steps, behaviors, components, parts, or combinations thereof may be present or added.

It should be further noted that the embodiments and features of the embodiments in the present disclosure may be combined with each other without conflict. The present disclosure will be described in detail below with reference to the accompanying drawings in conjunction with embodiments.

According to the invention, based on a cable noise source channel, electrical parameters such as equivalent resistance, equivalent capacitance and equivalent inductance are analyzed, and by designing structures such as a conductor layer, an insulating layer, a shielding layer and a wave-absorbing layer, the flexibility and toughness of the cable are improved as much as possible on the premise of ensuring that the diameter of the cable is not increased, so that the adaptability of the cable in use under a complex environment is ensured. Meanwhile, the cable has excellent performances of low noise, high shielding, high temperature resistance, irradiation resistance and the like through means such as material selection, manufacturing process and the like.

According to an embodiment of the present invention, a low-noise high-shielding fA-class current signal cable for a radiation environment is provided, as shown in fig. 1, and includes:

an inner conductor 1 disposed in the center of the cable;

the outer layer of cladding in inner conductor 1 wraps insulating layer 2, wraps semi-conducting layer 3, outer conductor 4, inner sheath 5, outer shielding layer 6, inhale ripples functional layer 7 and oversheath 8 around in proper order.

Preferably, the inner conductor 1 is formed by twisting a plurality of silver-plated copper wires around a central reinforcing filling fiber, so that the inner conductor 1 has good flexibility, high conductivity and good bending fatigue resistance, and the transmission performance of the cable is improved. Wherein, the diameter of the single silver-plated copper wire can be 0.10mm-0.16 mm.

Preferably, the lapping insulating layer 2 is composed of a cross-linked polytetrafluoroethylene film, and the cross-linked polytetrafluoroethylene film has high insulating layer strength, good aging resistance, high temperature resistance and high irradiation resistance. The thickness of the cross-linked polytetrafluoroethylene film is 0.025-0.102 mm, and the cross-linked polytetrafluoroethylene film is woven in a wrapping mode. After being irradiated by high-energy rays or particles under specific process conditions, polytetrafluoroethylene molecules are converted from a linear structure to a cross-linked polytetrafluoroethylene insulating layer with a three-dimensional network structure, and the insulating layer has high strength, good aging resistance, high temperature resistance and high irradiation resistance. The tension control system of the servo motor can be used for controlling the wrapping tension to be 100-200N, the online monitoring feedback system of the wrapping pitch is used for controlling the wrapping pitch to be 0.03-0.05 mm, and the wrapping pitch is monitored through data acquisition. The external diameter of the winding package can be monitored on line by adjusting process parameters and adding a diameter measuring instrument at the position of the winding head, and the insulating appearance can be more round and more complete by placing a sizing die at a wire outlet and adopting a mechanical fine adjustment mode, so that the consistency of the external diameter is improved.

Preferably, the wrapping semi-conductive layer 3 is composed of semi-conductive cross-linked polytetrafluoroethylene or polytetrafluoroethylene film, can be used for releasing distributed charges under the action of mechanical stress and is easy to peel off, so that electrostatic noise generated by bending or vibration when the cable works is reduced, and the transmission of weak signals is prevented from being influenced. The thickness of film is 0.025 ~ 0.102mm, adopts around the package mode to weave. The tension control system of the servo motor can be used for controlling the wrapping tension to be 150-300N, the online monitoring feedback system of the wrapping pitch is used for controlling the wrapping pitch to be 0.03-0.05 mm, and the wrapping pitch is monitored through data acquisition. The external diameter of the winding package can be monitored on line by adjusting process parameters and adding a diameter measuring instrument at the position of the winding head, and the insulating appearance can be more round and more complete by placing a sizing die at a wire outlet and adopting a mechanical fine adjustment mode, so that the consistency of the external diameter is improved.

Preferably, the outer conductor 4 is formed by weaving a shielding layer with a copper wire wrapping the outer of the wrapping semi-conducting layer 3, so that the bending or deformation of the cable is facilitated, the bending fatigue resistance is good, the stability is high, the induced potential on the surface of the cable can be eliminated, and the signal isolation effect is achieved. The number of weaving ingots of the copper wire is 24 or 16, the diameter of a single copper wire is 0.08mm or 0.10mm, the stable and uniform tension among the spindles can be ensured by adjusting the weaving pitch, the wire jumping of the copper wire with small tension caused by the tension difference is avoided, and finally burrs are trimmed and leveled.

Preferably, the inner sheath 5 is made of fluoroplastic (such as polytetrafluoroethylene, polyperfluoroethylene, ethylene-tetrafluoroethylene copolymer, polyvinylidene fluoride, polyvinyl fluoride or tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride) with excellent temperature resistance, and has high temperature resistance, good stability and capability of ensuring the comprehensive performance of the cable. The extrusion temperature and the process of the inner sheath 5 can be determined in sections according to the material characteristics, and warm water is adopted for cooling in sections step by step, so that the cracking of the inner sheath 5 can be reduced. When the inner sheath die is selected, the proper stretching ratio can be set so as to avoid the phenomena of cracking or necking caused by the internal stress formed by the excessive stretching of the material.

Preferably, the outer shielding layer 6 is a silver-plated copper wire braided shielding structure, and plays a role in signal isolation and electromagnetic interference resistance. The shielding effectiveness and the flexibility of the cable are combined, the weaving density of the low-noise cable is controlled to be more than or equal to 90%, and the weaving angle (the included angle between the strand direction and the axial direction of the cable) is controlled to be 18-40 degrees, so that the shielding performance of the cable is improved. The number of weaving spindles is 16 or 24, the diameter of a single silver-plated copper wire is 0.08mm or 0.10mm, the stable and uniform tension among the spindles can be ensured by adjusting the weaving pitch, and finally burrs are trimmed and leveled.

Preferably, the wave-absorbing functional layer 7 is obtained by coating a conductive adhesive and a wave-absorbing ferrite film coating on the outer shielding layer 6, so as to reduce the number of interfering electromagnetic waves and optimize the overall electromagnetic environment of the system. The thickness of the wave-absorbing ferrite film coating is 0.010-0.050 mm, and the wave-absorbing ferrite film coating is woven in a wrapping mode. The tension control system of the servo motor can be adopted to control the wrapping tension to be 100-200N, the online monitoring feedback system of the wrapping pitch is adopted to control the wrapping pitch to be +/-0.03 mm, and the wrapping pitch is monitored through data acquisition. The external diameter of the winding package can be monitored on line by adjusting process parameters and adding a diameter measuring instrument at the position of the winding head, and the insulating appearance can be more round and more complete by placing a sizing die at a wire outlet and adopting a mechanical fine adjustment mode, so that the consistency of the external diameter is improved.

Preferably, the outer sheath 8 is made of high-density polyethylene with excellent radiation resistance, and has good heat resistance and high mechanical strength, so as to further improve the applicability of the cable. The extrusion temperature and the process of the outer sheath 8 can be determined in sections according to the material characteristics, and warm water is adopted for cooling in sections step by step, so that the cracking of the outer sheath 8 can be reduced. When the outer sheath die is selected, the proper stretching ratio is set to avoid the phenomena of cracking or end shrinkage and the like caused by the internal stress formed by the excessive stretching of the material.

The structure of the low-noise high-shielding fA class current signal cable for the radiation environment of the present invention is described in several embodiments.

Example 1

As shown in fig. 1, the low-noise high-shielding fA-class current signal cable for radiation environment comprises:

an inner conductor 1 disposed in the center of the cable;

the outer layer of cladding in inner conductor 1 wraps insulating layer 2, wraps semi-conducting layer 3, outer conductor 4, inner sheath 5, outer shielding layer 6, inhale ripples functional layer 7 and oversheath 8 around in proper order.

Preferably, the inner conductor 1 is formed by twisting 19 silver-plated copper wires around a central reinforcing filler fiber, wherein the diameter of each silver-plated copper wire can be 0.10mm, 0.12mm or 0.16 mm.

Preferably, the lapping insulating layer 2 is composed of a cross-linked polytetrafluoroethylene film, and the cross-linked polytetrafluoroethylene film has high insulating layer strength, good aging resistance, high temperature resistance and high irradiation resistance. The thickness of the cross-linked polytetrafluoroethylene film is 0.025-0.051 mm, and the cross-linked polytetrafluoroethylene film is woven in a wrapping mode. The tension control system of the servo motor can be adopted to control the wrapping tension to be 100-200N, the online monitoring feedback system of the wrapping pitch is adopted to control the wrapping pitch to be +/-0.03 mm, and the wrapping pitch is monitored through data acquisition. The external diameter of the winding package can be monitored on line by adjusting process parameters and adding a diameter measuring instrument at the position of the winding head, and the insulating appearance can be more round and more complete by placing a sizing die at a wire outlet and adopting a mechanical fine adjustment mode, so that the consistency of the external diameter is improved.

Preferably, the lapped semi-conductive layer 3 is composed of a semi-conductive cross-linked polytetrafluoroethylene or polytetrafluoroethylene film, the thickness of the film is 0.025-0.051 mm, and the film is woven in a lapped mode. The tension control system of the servo motor can be adopted to control the wrapping tension to be 150-300N, the online monitoring feedback system of the wrapping pitch is adopted to control the wrapping pitch to be +/-0.03 mm, and the wrapping pitch is monitored through data acquisition. The external diameter of the winding package can be monitored on line by adjusting process parameters and adding a diameter measuring instrument at the position of the winding head, and the insulating appearance can be more round and more complete by placing a sizing die at a wire outlet and adopting a mechanical fine adjustment mode, so that the consistency of the external diameter is improved.

Preferably, the outer conductor 4 is composed of a copper wire braided shielding layer coated outside the wrapped semi-conducting layer 3, the number of braided ingots is 24 or 16, the diameter of each copper wire is 0.08mm or 0.10mm, the stable and uniform tension between spindles can be ensured by adjusting the braiding pitch, the wire jumping of the copper wire with small tension caused by tension difference is avoided, and finally burrs are trimmed and leveled.

Preferably, the inner sheath 5 is made of fluoroplastic (such as polytetrafluoroethylene, polyperfluoroethylene, ethylene-tetrafluoroethylene copolymer, polyvinylidene fluoride, polyvinyl fluoride, or tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride) with excellent temperature resistance, and has high temperature resistance and good stability. The extrusion temperature and the process of the inner sheath 5 can be determined in sections according to the material characteristics, and warm water is adopted for cooling in sections step by step, so that the cracking of the inner sheath 5 can be reduced. When the inner sheath die is selected, the proper stretching ratio can be set so as to avoid the phenomena of cracking or necking caused by the internal stress formed by the excessive stretching of the material.

Preferably, the outer shielding layer 6 is of a silver-plated copper wire braided shielding structure, the braiding density of the low-noise cable is controlled to be larger than or equal to 90%, and the braiding angle (the included angle between the strand direction and the cable axis direction) is controlled to be 18-40 degrees, so that the shielding performance of the cable is improved. The number of weaving spindles is 16, the diameter of a single silver-plated copper wire is 0.08mm or 0.10mm, the stable and uniform tension among the spindles can be ensured by adjusting the weaving pitch, and finally burrs are trimmed and leveled.

Preferably, the wave-absorbing functional layer 7 is formed by coating a conductive adhesive and a wave-absorbing ferrite film coating on the outer shielding layer 6, the thickness of the wave-absorbing ferrite film coating is 0.030-0.050 mm, and the wave-absorbing ferrite film coating is woven in a wrapping mode. The tension control system of the servo motor can be adopted to control the wrapping tension to be 100-200N, the online monitoring feedback system of the wrapping pitch is adopted to control the wrapping pitch to be +/-0.03 mm, and the wrapping pitch is monitored through data acquisition. The external diameter of the winding package can be monitored on line by adjusting process parameters and adding a diameter measuring instrument at the position of the winding head, and the insulating appearance can be more round and more complete by placing a sizing die at a wire outlet and adopting a mechanical fine adjustment mode, so that the consistency of the external diameter is improved.

Preferably, the outer sheath 8 is made of high-density polyethylene having excellent irradiation resistance, and has good heat resistance and high mechanical strength. The extrusion temperature and the process of the outer sheath 8 can be determined in sections according to the material characteristics, and warm water is adopted for cooling in sections step by step, so that the cracking of the outer sheath 8 can be reduced. When the outer sheath die is selected, the proper stretching ratio is set to avoid the phenomena of cracking or end shrinkage and the like caused by the internal stress formed by the excessive stretching of the material.

The characteristic parameters of the low-noise high-shielding fA-level current signal cable for the radiation environment prepared according to the scheme are shown in Table 1:

TABLE 1

Example 2

As shown in fig. 1, the low-noise high-shielding fA-class current signal cable for radiation environment comprises:

an inner conductor 1 disposed in the center of the cable;

the outer layer of cladding in inner conductor 1 wraps insulating layer 2, wraps semi-conducting layer 3, outer conductor 4, inner sheath 5, outer shielding layer 6, inhale ripples functional layer 7 and oversheath 8 around in proper order.

Preferably, the inner conductor 1 is formed by stranding 26 silver-plated copper wires around a central reinforcing filler fiber, wherein the diameter of each silver-plated copper wire can be 0.10mm or 0.12 mm.

Preferably, the lapping insulating layer 2 is composed of a cross-linked polytetrafluoroethylene film, and the cross-linked polytetrafluoroethylene film has high insulating layer strength, good aging resistance, high temperature resistance and high irradiation resistance. The thickness of the cross-linked polytetrafluoroethylene film is 0.025-0.102 mm, and the cross-linked polytetrafluoroethylene film is woven in a wrapping mode. The tension control system of the servo motor can be adopted to control the wrapping tension to be 100-200N, the online monitoring feedback system of the wrapping pitch is adopted to control the wrapping pitch to be +/-0.05 mm, and the wrapping pitch is monitored through data acquisition. The external diameter of the winding package can be monitored on line by adjusting process parameters and adding a diameter measuring instrument at the position of the winding head, and the insulating appearance can be more round and more complete by placing a sizing die at a wire outlet and adopting a mechanical fine adjustment mode, so that the consistency of the external diameter is improved.

Preferably, the lapped semi-conductive layer 3 is composed of a semi-conductive polytetrafluoroethylene film, the thickness of the film is 0.051-0.102 mm, and the film is woven in a lapped mode. The tension control system of the servo motor can be adopted to control the wrapping tension to be 150-300N, the online monitoring feedback system of the wrapping pitch is adopted to control the wrapping pitch to be +/-0.05 mm, and the wrapping pitch is monitored through data acquisition. The external diameter of the winding package can be monitored on line by adjusting process parameters and adding a diameter measuring instrument at the position of the winding head, and the insulating appearance can be more round and more complete by placing a sizing die at a wire outlet and adopting a mechanical fine adjustment mode, so that the consistency of the external diameter is improved.

Preferably, the outer conductor 4 is composed of a copper wire braided shielding layer coated outside the wrapped semi-conducting layer 3, the number of braided ingots is 24, the diameter of each copper wire is 0.08mm or 0.10mm, the tension between the spindles can be guaranteed to be stable and uniform by adjusting the braiding pitch, wire jumping of the copper wires with small tension caused by tension difference is avoided, and finally burrs are trimmed and leveled by scissors or other methods.

Preferably, the inner sheath 5 is made of fluoroplastic (such as polytetrafluoroethylene, polyperfluoroethylene, ethylene-tetrafluoroethylene copolymer, polyvinylidene fluoride, polyvinyl fluoride, or tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride) with excellent temperature resistance, and has high temperature resistance and good stability. The extrusion temperature and the process of the inner sheath 5 can be determined in sections according to the material characteristics, and warm water is adopted for cooling in sections step by step, so that the cracking of the inner sheath 5 can be reduced. When the inner sheath die is selected, the proper stretching ratio can be set so as to avoid the phenomena of cracking or necking caused by the internal stress formed by the excessive stretching of the material.

Preferably, the outer shielding layer 6 is of a silver-plated copper wire braided shielding structure, the braiding density of the low-noise cable is controlled to be more than or equal to 92%, and the braiding angle (the included angle between the strand direction and the cable axis direction) is controlled to be 18-40 degrees, so that the shielding performance of the cable is improved. The number of weaving spindles is 24, the diameter of a single silver-plated copper wire is 0.08mm or 0.10mm, stable and uniform tension among the spindles can be guaranteed by adjusting weaving pitch, wire jumping of the copper wire with small tension caused by tension difference is avoided, and finally burrs are trimmed and leveled by scissors or other modes.

Preferably, the wave-absorbing functional layer 7 is formed by coating the conductive adhesive and a wave-absorbing ferrite film coating on the outer shielding layer 6, the thickness of the wave-absorbing ferrite film coating is 0.010-0.030 mm, and the wave-absorbing ferrite film coating is woven in a wrapping mode. The tension control system of the servo motor can be adopted to control the wrapping tension to be 100-200N, the online monitoring feedback system of the wrapping pitch is adopted to control the wrapping pitch to be +/-0.03 mm, and the wrapping pitch is monitored through data acquisition. The external diameter of the winding package can be monitored on line by adjusting process parameters and adding a diameter measuring instrument at the position of the winding head, and the insulating appearance can be more round and more complete by placing a sizing die at a wire outlet and adopting a mechanical fine adjustment mode, so that the consistency of the external diameter is improved.

Preferably, the outer sheath 8 is made of polyethylene having excellent irradiation resistance, and has good heat resistance and high mechanical strength. The extrusion temperature and the process of the outer sheath 8 can be determined in sections according to the material characteristics, and warm water is adopted for cooling in sections step by step, so that the cracking of the outer sheath 8 can be reduced. When the outer sheath die is selected, the proper stretching ratio is set to avoid the phenomena of cracking or end shrinkage and the like caused by the internal stress formed by the excessive stretching of the material.

The characteristic parameters of the low-noise high-shielding fA-level current signal cable for the radiation environment prepared according to the scheme are shown in Table 2:

TABLE 2

Cable performance	Index parameter
		Outer diameter of finished product	≤8.0mm
Characteristic impedance	1.5kVrms (sea level)
		Maximum operating voltage	(50Hz/1min)：3(kVrms)
Insulation resistance	≥1×103(MΩ·km)
		MVD level	5(mV)
Temperature range	-50～+200(℃)
		Radiation dose resistance	3Mrad

Example 3

As shown in fig. 1, the low-noise high-shielding fA-class current signal cable for radiation environment comprises:

an inner conductor 1 disposed in the center of the cable;

the outer layer of cladding in inner conductor 1 wraps insulating layer 2, wraps semi-conducting layer 3, outer conductor 4, inner sheath 5, outer shielding layer 6, inhale ripples functional layer 7 and oversheath 8 around in proper order.

Preferably, the inner conductor 1 is formed by stranding 26 silver-plated copper wires around a central reinforcing filler fiber, wherein the diameter of each silver-plated copper wire can be 0.12mm or 0.16 mm.

Preferably, the lapping insulating layer 2 is composed of a cross-linked polytetrafluoroethylene film, and the cross-linked polytetrafluoroethylene film has high insulating layer strength, good aging resistance, high temperature resistance and high irradiation resistance. The thickness of the cross-linked polytetrafluoroethylene film is 0.051-0.102 mm, and the cross-linked polytetrafluoroethylene film is woven in a wrapping mode. The tension control system of the servo motor can be adopted to control the wrapping tension to be 100-200N, the online monitoring feedback system of the wrapping pitch is adopted to control the wrapping pitch to be +/-0.04 mm, and the wrapping pitch is monitored through data acquisition. The external diameter of the winding package can be monitored on line by adjusting process parameters and adding a diameter measuring instrument at the position of the winding head, and the insulating appearance can be more round and more complete by placing a sizing die at a wire outlet and adopting a mechanical fine adjustment mode, so that the consistency of the external diameter is improved.

Preferably, the lapped semi-conductive layer 3 is composed of a semi-conductive polytetrafluoroethylene film, the thickness of the film is 0.025-0.051 mm, and the film can be woven in a lapped mode. The tension control system of the servo motor is adopted to control the wrapping tension to be 150-300N, the online monitoring feedback system of the wrapping pitch is adopted to control the wrapping pitch to be +/-0.04 mm, and the wrapping pitch is monitored through data acquisition. The external diameter of the winding package can be monitored on line by adjusting process parameters and adding a diameter measuring instrument at the position of the winding head, and the insulating appearance can be more round and more complete by placing a sizing die at a wire outlet and adopting a mechanical fine adjustment mode, so that the consistency of the external diameter is improved.

Preferably, the outer conductor 4 is composed of a copper wire braided shielding layer coated outside the wrapped semi-conducting layer 3, the number of braided ingots is 24, the diameter of each copper wire is 0.08mm or 0.10mm, the tension between the spindles can be guaranteed to be stable and uniform by adjusting the braiding pitch, wire jumping of the copper wires with small tension caused by tension difference is avoided, and finally burrs are trimmed and leveled by scissors or other methods.

Preferably, the inner sheath 5 is made of fluoroplastic (such as polytetrafluoroethylene, polyperfluoroethylene, ethylene-tetrafluoroethylene copolymer, polyvinylidene fluoride, polyvinyl fluoride, or tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride) with excellent temperature resistance, and has high temperature resistance and good stability. The extrusion temperature and the process of the inner sheath 5 can be determined in sections according to the material characteristics, and warm water is adopted for cooling in sections step by step, so that the cracking of the inner sheath 5 can be reduced. When the inner sheath die is selected, the proper stretching ratio can be set so as to avoid the phenomena of cracking or necking caused by the internal stress formed by the excessive stretching of the material.

Preferably, the outer shielding layer 6 is of a silver-plated copper wire braided shielding structure, the braiding density of the low-noise cable is controlled to be not less than 92%, and the braiding angle (the included angle between the strand direction and the cable axis direction) is controlled to be 18-40 degrees, so that the shielding performance of the cable is improved. The number of weaving spindles is 24, the diameter of a single silver-plated copper wire is 0.08mm or 0.10mm, stable and uniform tension among the spindles can be guaranteed by adjusting weaving pitch, wire jumping of the copper wire with small tension caused by tension difference is avoided, and finally burrs are trimmed and leveled by scissors or other modes.

Preferably, the wave-absorbing functional layer 7 is formed by coating the conductive adhesive and a wave-absorbing ferrite film coating on the outer shielding layer 6, the thickness of the wave-absorbing ferrite film coating is 0.010-0.030 mm, and the wave-absorbing ferrite film coating is woven in a wrapping mode. The tension control system of the servo motor can be adopted to control the wrapping tension to be 100-200N, the online monitoring feedback system of the wrapping pitch is adopted to control the wrapping pitch to be +/-0.03 mm, and the wrapping pitch is monitored through data acquisition. The external diameter of the winding package can be monitored on line by adjusting process parameters and adding a diameter measuring instrument at the position of the winding head, and the insulating appearance can be more round and more complete by placing a sizing die at a wire outlet and adopting a mechanical fine adjustment mode, so that the consistency of the external diameter is improved.

Preferably, the outer sheath 8 is made of polyethylene having excellent irradiation resistance, and has good heat resistance and high mechanical strength. The extrusion temperature and the process of the outer sheath 8 can be determined in sections according to the material characteristics, and warm water is adopted for cooling in sections step by step, so that the cracking of the outer sheath 8 can be reduced. When the outer sheath die is selected, the proper stretching ratio is set to avoid the phenomena of cracking or end shrinkage and the like caused by the internal stress formed by the excessive stretching of the material.

The characteristic parameters of the low-noise high-shielding fA-level current signal cable for the radiation environment prepared according to the scheme are shown in Table 3:

TABLE 3

Cable performance	Index parameter
		Outer diameter of finished product	≤10.0mm
Characteristic impedance	1.5kVrms (sea level)
		Maximum operating voltage	(50Hz/1min)：3(kVrms)
Insulation resistance	≥1×103(MΩ·km)
		MVD level	5(mV)
Temperature range	-50～+200(℃)
		Radiation dose resistance	5Mrad

According to another embodiment of the present invention, a manufacturing process of a low-noise high-shielding fA-class current signal cable for a radiation environment is further provided, as shown in fig. 2, the manufacturing process of the low-noise high-shielding fA-class current signal cable for the radiation environment includes the following steps:

step S1, stranding a plurality of silver-plated copper wires around the center reinforced filling fiber to form an inner conductor 1, and arranging the inner conductor 1 at the center of the cable;

step S2, weaving the outer layer of the inner conductor 1 by using a cross-linked polytetrafluoroethylene film in a wrapping mode to obtain a wrapping insulating layer 2 wrapping the outer layer of the inner conductor 1;

step S3, weaving the outer layer of the wrapped insulating layer 2 by using a semi-conductive cross-linked polytetrafluoroethylene or polytetrafluoroethylene film in a wrapping mode to obtain a wrapped semi-conductive layer 3 coated on the outer layer of the wrapped insulating layer 2;

step S4, weaving a copper wire to obtain a shielding layer coated on the outer layer of the wrapped semiconductive layer 3, and obtaining an outer conductor 4;

step S5, preparing an inner sheath 5 on the outer layer of the outer conductor 4 using fluoroplastic;

step S6, weaving silver-plated copper wires on the outer layer of the inner sheath 5 to obtain an outer shielding layer 6;

step S7, weaving the outer layer of the outer shielding layer 6 by using conductive adhesive and a wave-absorbing ferrite film in a wrapping mode to obtain a wave-absorbing functional layer 7;

and step S8, preparing the outer sheath 8 on the outer layer of the wave-absorbing functional layer 7 by using high-density polyethylene.

In the wrapping step, a tension control system of a servo motor can be adopted to control the wrapping tension, an online wrapping pitch monitoring feedback system is adopted to control the wrapping pitch to be +/-0.03 mm- +/-0.05 mm, the wrapping pitch is monitored through data acquisition, and when the pitch fluctuation exceeds a set value, an automatic alarm is given and the vehicle is stopped. By adjusting process parameters, a diameter measuring instrument is added at the position of a wrapping head to perform online monitoring on the outer diameter of the wrapping, a sizing die is placed at a wire outlet, the insulating appearance is more round and more complete by adopting a mechanical fine adjustment mode, and the consistency of the outer diameter is improved.

In the weaving step, reasonable parameters such as weaving spindle number, monofilament diameter, weaving pitch and the like are determined firstly, and then, in the weaving process, stable and uniform tension among spindles is ensured, so that the phenomenon that the copper wire with small tension jumps due to tension difference is avoided. Finally, when the spindle is replaced, the burrs need to be trimmed and leveled.

The sheath preparation step firstly determines the extrusion temperature and the process in sections according to the used materials, and adopts warm water to cool in sections step by step, so as to reduce the cracking of the sheath. When the die is selected and matched, a smaller stretching ratio is adopted to avoid the phenomenon that the material is excessively stretched and the phenomenon of cracking or necking caused by the formation of internal stress is avoided.

Technical terms and technical features related to the embodiment are the same as or similar to those of the technical terms and technical features shown in fig. 1 and mentioned in the related embodiment, and for the explanation and description of the technical terms and technical features related to the embodiment, reference may be made to the above explanation of the technical terms and technical features shown in fig. 1 and mentioned in the related embodiment, and detailed description thereof is omitted.

The foregoing description is only exemplary of the preferred embodiments of the disclosure and is illustrative of the principles of the technology employed. It will be appreciated by those skilled in the art that the scope of the invention in the present disclosure is not limited to the specific combination of the above-mentioned features, but also encompasses other embodiments in which any combination of the above-mentioned features or their equivalents is possible without departing from the inventive concept. For example, the above features and (but not limited to) the features disclosed in this disclosure having similar functions are replaced with each other to form the technical solution.

Claims (10)

1. A low-noise high-shielding class fA current signal cable for radiation environments, comprising:

an inner conductor disposed in the center of the cable;

the wave-absorbing cable comprises a wrapping insulating layer, a wrapping semi-conducting layer, an outer conductor, an inner sheath, an outer shielding layer, a wave-absorbing functional layer and an outer sheath which are sequentially coated on the outer layer of the inner conductor.

2. The cable of claim 1, the inner conductor being comprised of a plurality of silver-plated copper wires stranded around a central reinforcing filler fiber.

3. The cable of claim 1, said wrapped insulation layer being comprised of a cross-linked polytetrafluoroethylene film.

4. The cable of claim 1, the wrapped semiconductive layer consisting of polytetrafluoroethylene film or cross-linked polytetrafluoroethylene film.

5. The cable of claim 1, the outer conductor consisting of a braided shield of copper wire wrapped around a semi-conductive layer.

6. The cable of claim 1, the inner jacket being comprised of a fluoroplastic.

7. The cable according to claim 1, wherein the outer shielding layer is a shielding structure woven by silver-plated copper wires.

8. The cable according to claim 1, wherein the wave absorbing functional layer is obtained by coating a conductive adhesive and a wave absorbing ferrite coating film on the outer shielding layer.

9. The cable of claim 1, the outer jacket consisting of high density polyethylene.

10. A process for manufacturing a low-noise high-shielding class fA current signal cable for a radiation environment according to claim 1, comprising the steps of:

step S1, stranding a plurality of silver-plated copper wires around the center reinforced filling fiber to form an inner conductor, and arranging the inner conductor at the center of the cable;

step S2, weaving the outer layer of the inner conductor by using a cross-linked polytetrafluoroethylene film in a wrapping mode to obtain a wrapping insulating layer wrapping the outer layer of the inner conductor;

step S3, weaving the outer layer of the wrapped insulating layer by using a semi-conductive cross-linked polytetrafluoroethylene or polytetrafluoroethylene film in a wrapping mode to obtain a wrapped semi-conductive layer coated on the outer layer of the wrapped insulating layer;

step S4, weaving copper wires to obtain a shielding layer, and coating the shielding layer on the outer layer of the wrapped semi-conductive layer to obtain an outer conductor;

step S5, preparing an inner sheath on the outer layer of the outer conductor by using fluoroplastic;

step S6, weaving silver-plated copper wires on the outer layer of the inner sheath to obtain an outer shielding layer;

step S7, weaving the outer layer of the outer shielding layer by using conductive adhesive and a wave-absorbing ferrite film in a wrapping mode to obtain a wave-absorbing functional layer;

and step S8, preparing an outer sheath on the outer layer of the wave-absorbing functional layer by using high-density polyethylene.

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