阅读说明：本技术 60年寿命抗辐射耐火通信电缆及其制备方法 (Anti-radiation fire-resistant communication cable with 60-year service life and preparation method thereof ) 是由 韩志东 顾申杰 魏林强 陆佩芳 王彩生 景弋 何健 陈航 徐成 沈建宇 冯胜 于 2019-03-04 设计创作，主要内容包括：60年寿命抗辐射耐火通信电缆及其制备方法,属于电缆制备技术领域；本发明公开了60年寿命抗辐射耐火通信电缆及其制备方法是由导体、绝缘、星绞、绕包层、定型层、成缆、隔火填充层、外护套构成；成品电缆具有外径小、重量轻,能经受火焰温度850℃,持续供火时间180min的个试验要求。(A60-year-life radiation-resistant and fire-resistant communication cable and a preparation method thereof belong to the technical field of cable preparation; the invention discloses a 60-year-life anti-radiation fire-resistant communication cable and a preparation method thereof, wherein the communication cable is composed of a conductor, insulation, star stranding, a wrapping layer, a shaping layer, a cabling layer, a fire insulation filling layer and an outer sheath; the finished cable has small outer diameter and light weight, and can withstand the test requirements of flame temperature of 850 ℃ and continuous fire supply time of 180 min.)

The anti-radiation fire-resistant communication cable with the service life of 1.60 years and the preparation method thereof comprise a conductor, insulation, star stranding, a wrapping layer, a shaping layer, cabling, a fire insulation filling layer and an outer sheath; the insulation is formed by extruding novel silica gel polyolefin, and the thickness of the thinnest part is 0.15 mm; the star quad is formed by twisting four insulated single lines with different colors according to different pitches; the wrapping is to wrap a layer of flame-retardant wrapping tape after the star-twisted group is wrapped; the shaping layer is formed by wrapping or extruding a layer of halogen-free low-smoke flame-retardant shaping layer; cabling is formed by cabling a plurality of pairs of twisted wires together by adopting a proper twisting pitch; the fire-insulating filling layer is made of heat-insulating low-smoke halogen-free flame-retardant polyolefin material; the outer sheath is formed by extruding and wrapping a crusting low-smoke halogen-free flame-retardant polyolefin sheath.

2. The radiation and fire resistant communication cable having a life of 60 years as claimed in claim 1, wherein the insulating material is extruded using a plastic extrusion process having a length to diameter ratio of 16:1, extruding by using a full-thread screw with equidistant threads and gradually changed thread depth.

3. The radiation-resistant and fire-resistant communication cable with 60-year life as claimed in claim 1 and the preparation method thereof, wherein the die sleeve is designed without bearing diameter in the insulating material extrusion process, the die core is designed with an ultra-short nozzle to reduce the inner bearing diameter, and the tail of the lead-in conductor positioning device is increased.

Technical Field

A60-year-life radiation-resistant and fire-resistant communication cable and a preparation method thereof belong to the technical field of cable preparation.

Background

The 60-year-life radiation-resistant cable is mainly applied to nuclear reactor plants, nuclear auxiliary plants, network control buildings, rail transit machine rooms and the like, and is required to have the characteristics of long service life, radiation resistance, heat resistance, moisture resistance and the like due to the special environment of the cable. The anti-radiation fire-resistant communication cable with the service life of 60 years not only has higher requirements on the safety performances of the cable, such as flame retardant performance, fire resistance and the like, but also is required to keep the smoothness of signals and the stability of electric performance transmission in the cable combustion environment.

The general structural style of fire-resistant communication cable on the market at present:

the wrapping type fireproof layer and the polyolefin insulating composite insulating layer are arranged on the wrapping type fireproof layer. The structure form is mainly that the conductor is wrapped with one or more layers of reinforced mica tapes or synthetic mica fireproof tapes and then extruded with crosslinked polyethylene or polyethylene insulation with medium and high density, and the wrapped structure insulation has the following defects: the condition that the lapping layer is not attached unevenly can be caused no matter one or more layers of refractory tape are lapped, and firstly, the condition that the lapping tapes are overlapped exists in the refractory tape lapping; secondly, a wrapping gap exists in the wrapping of the fire-resistant wrapping tape; thirdly, even if the wrapping quality is perfect, gaps exist among the wrapping tapes as long as the wrapping wires are bent. Therefore, the uneven wrapping of the wrapping layer can lead to uneven squeezing of the insulating layer, the difference of the insulating thickness is uneven, and the electric parameters of the cable such as impedance, return loss and the like are unqualified. Meanwhile, in order to ensure that the cable passes a harsh fire resistance test, more layers of fire-resistant wrapping tapes are wrapped, and an insulating layer disappears due to combustion and carbonization, so that the structure of the cable is changed, and the electrical parameters such as impedance, return loss and the like of the cable are unqualified, thereby causing distortion of transmission signals.

In order to avoid the defect of poor reliability of the cable structure, manufacturers at home and abroad mainly aim to develop a mica tape with higher fire resistance and optimize a wrapping process so as to solve the problem of unbalanced outer diameter and insulation thickness of the cable and avoid the transmission performance of the cable in a fire resistance test.

Disclosure of Invention

The invention aims to develop a novel 60-year-life radiation-resistant fire-resistant communication cable. The novel silicon rubber polyolefin insulating material with fire resistance is adopted for insulation, the wrapping fire-resistant layer is not wrapped, the inner layer and the outer layer of the jacket are directly extruded outside the conductor, and then twisting, cabling and extruding are carried out, so that the transmission performance during the fire-resistant time is kept.

In order to achieve the purpose, the technical scheme of the invention is as follows:

the anti-radiation fire-resistant communication cable with the service life of 60 years is composed of a conductor, insulation, star twists, a wrapping layer, shaping, cabling, a fire insulation filling layer and an outer sheath;

the novel silicon rubber polyolefin cable is characterized in that the novel silicon rubber polyolefin with excellent fire resistance is extruded and wrapped for insulation, and the thickness of the thinnest part is 0.15 mm;

the star quad is formed by stranding four insulated single wires with different colors according to different pitches;

the wrapping is characterized in that a flame-retardant wrapping tape is wrapped after the star-twisted group is wrapped, so that scalding during extrusion is prevented;

the shaping layer is wrapped or extruded with a layer of halogen-free low-smoke flame-retardant shaping layer to ensure the core wire fixing position of the fireproof star-twisted set;

the method is characterized in that cabling is carried out by adopting proper stranding pitch, and a plurality of pairs of twisted wires are cabled together to stabilize the structure of each wire group of the cable core;

the cable is characterized in that the fire insulation filling layer is made of a heat insulation type low-smoke halogen-free flame-retardant polyolefin material, so that the influence of high temperature generated by cable combustion on a wire core is prevented;

the outer sheath is formed by extruding and wrapping a crusting low-smoke halogen-free flame-retardant polyolefin sheath.

In order to realize the extrusion process of the insulating material, the length-diameter ratio of the insulating material is 16:1, extruding by using a full-thread screw with equidistant threads and gradually changed depth; the die sleeve adopts the design without bearing diameter, the die core adopts the design of an ultra-short nozzle to reduce the inner bearing diameter, and the tail of the lead-in front conductor positioning device is increased, so that the conductor is positioned more stably, the extrusion insulation core deviation degree is good, and the stable extrusion of the refractory insulation material is realized.

Due to the characteristics of the formula of the novel silicon rubber polyolefin insulation material, a screw of a conventional extruding machine cannot meet the production requirement, and the problems of unstable glue yield or incomplete vulcanization and the like are easily caused, so that the extrusion of an insulation layer is one of the difficulties in process implementation. We have mainly carried out process verification and improvement from the following aspects:

firstly, due to the design of the screw, the insulating material cannot be in the machine body for too long or too short time, the insulating layer is easy to have bubbles when the time is too long, and the insulating material is not fully vulcanized when the time is too short. Three sections of the screw are reasonable, and mixing and melting vulcanization of the insulating material are facilitated. Through calculation and verification, the length-diameter ratio of the screw is reduced from (20-30): 1 to 16: 1. Because the fluidity of the insulating material is slightly poor, the frictional resistance generated when the screw rotates is reduced by reducing the width of the screw edge of the screw, and the insulating extrusion speed is accelerated. The screw is designed to be a screw with equal depth and unequal distance or an equidistant and unequal depth mutant type, and in order to achieve the purposes of accelerating the extrusion speed and keeping the extrusion pressure stable, a full-thread screw with equal distance and gradually changed thread depth, wherein the end part of the full-thread screw is deeper, and the root part of the full-thread screw is shallower is adopted.

Secondly, the extrusion die is not enough, the extrusion pressure is only improved by a screw, the extrusion die is required to be improved, and the sectional views of the die before and after the improvement are as follows: a. the die core and the fireproof insulating material are extremely sensitive to temperature, the inner bearing diameter and the outer bearing diameter of the die core are properly shortened, a material flow channel is smooth, and the damage of a conductor to the heat balance of an extrusion die during the extrusion of an inner insulating layer is well avoided, so that the high precision of the temperature control of an extrusion layer is practically ensured; a tail positioning device is added, so that the stability of adjusting eccentricity of the cable is improved; b. the die sleeve is poor in flowability of the fireproof insulating material, the requirement on the die is high, a conventional extrusion mode is adopted, unstable discharging phenomenon easily occurs in an extrusion type mode, an extrusion type mode or a semi-extrusion type mode, the extrusion cannot be normally extruded seriously, the defect that the pressure of an extrusion type material flow at a die opening is unstable, the defect that resistance is easily applied to an extrusion type material flow at a die sleeve bearing diameter position is overcome, a die core nozzle of the extrusion type mode and the die sleeve bearing diameter of the extrusion type mode are eliminated, and therefore the material flow is smoother and more perfect in plasticization when the inner insulating layer is extruded.

Compared with the existing product, the cable structure has the following characteristics: the outer diameter is small, and because the process of wrapping a fire-resistant belt by an independent fire-resistant layer is reduced during the structural design of the cable, the novel silicon rubber polyolefin insulation with fire-resistant property is directly extruded on the conductor, and the outer diameter of single insulation is reduced, so that the outer diameter of a twisted pair cable and a cabled cable to a finished cable is reduced, and the outer diameter of the finished cable is smaller; light weight due to the low specific gravity of silicone rubber polyolefin insulation (the specific gravity of silicone rubber is about 1.1 g/cm)³The other overall density is about 85 percent of the combined insulation comprehensive density of the fire-resistant lapping layer), in addition, the outer diameter is reduced after the lapping process is reduced, and the weight of the finished cable meets the weight reduction requirement of cable laying; flame combustion resistance, and the insulation is made of refractory materials, so that the cable can be kept for a certain time under the condition of flame combustionThe high-voltage insulation material has the advantages of safe operation capability and considerable transmission performance (the high-voltage insulation material can withstand flame temperature of 850 ℃, the continuous fire supply time of 180min, the test sample can withstand the rated voltage value specified by the product during the whole test period, is not broken down, and has characteristic impedance and attenuation kept to be not less than 50%), long service life, no obvious change in physical and electrical characteristics of the insulation material and the sheath under the action of continuous heat aging at 65 ℃ in the service life of a power plant of 60 years, and capability of withstanding radiation accumulation agent accumulation under the normal working condition of 60 years (300 × 10)⁵GY) without any significant change in its physical and electrical properties; the novel silicon rubber polyolefin insulation and low-smoke halogen-free flame-retardant oxygen-isolating layer has excellent self-extinguishing performance, has good flame-retardant effect, can only be carbonized under the direct baking of flame, but does not peel off crusts, and plays a role in protecting the inner layer structure.

The innovation points of the preparation method of the product are mainly shown as follows: the special novel silicon rubber polyolefin insulation is adopted to replace a fire-resistant belt winding and extruding insulation structure, so that the outer diameter and weight of the cable are reduced, and the communication transmission performance is stable; the novel silicon rubber polyolefin insulating material can withstand the flame temperature of 850 ℃ and can continuously supply fire for 180min, and during the whole test period, a sample is required to bear the rated voltage value of 90V specified by a product, so that the breakdown is avoided, the insulating appearance is unchanged, and the electrical transmission performance is not reduced; the novel silicon rubber polyolefin insulation and low-smoke halogen-free flame-retardant irradiation polyolefin sheath is adopted to improve the thermal aging life and the irradiation life of the insulation and the sheath, and the 40-year life of the common nuclear power cable is prolonged to 60 years; the specially designed small length-diameter ratio screw and the full-thread screw with the equal distance and gradually changed thread depth are adopted to ensure the good mechanical property of the extruded insulating material; the die sleeve adopts the process design without bearing diameter, the die core adopts the process design of 'ultra short nozzle' to reduce the inner bearing diameter, and the tail of the lead-in front conductor positioning device is added, so that the conductor is positioned more stably, the extrusion insulation core deviation degree is good, and the stable extrusion of the refractory insulation material is realized.

Drawings

FIG. 1 shows a 60-year-life radiation-resistant and fire-resistant communication cable

1-copper conductor 2-fireproof silica gel polyolefin insulation 3-lapping layer 4-halogen-free extrusion molding layer 5-fire insulation filling layer 6-halogen-free low-smoke irradiation crosslinking polyolefin sheath material.

FIG. 2 is a comparison of extrusion die modifications.

Detailed Description

A conductor: according to the requirements of high temperature resistance and environment resistance of the cable, the conductor adopts a tinned soft copper stranded wire.

Insulating: the novel silica gel polyolefin with excellent fire resistance is adopted for extrusion coating, and the thickness of the thinnest part is 0.15 mm.

Carrying out star stranding: the star twist is formed by twisting four insulated single wires with different colors according to different pitches, so that the electrical performance of the wire groups with different frequencies is ensured, and the electrical transmission performance requirement of the cable is met.

Lapping: a flame-retardant wrapping tape is wrapped after the star-twisted group, so that scalding during extrusion is prevented.

Shaping layer: and a halogen-free low-smoke flame-retardant shaping layer is wrapped or extruded to ensure the fixing position of the core wire of the fire-resistant star-twisted group.

Sixthly, cabling: and proper stranding pitch is adopted, and a plurality of pairs of twisted wires are cabled together to stabilize the structure of each wire group of the cable core, so that the crosstalk index and the anti-interference performance of the cable are improved.

Seventh, fire-blocking filling layer: and the heat-insulation low-smoke halogen-free flame-retardant polyolefin material is adopted, so that the influence of high temperature generated by cable combustion on the wire core is prevented.

Eighthly, outer sheath: the outer sheaths are all extruded by the crusting low-smoke halogen-free flame-retardant polyolefin sheaths, the material has the characteristics of low smoke and low toxicity, the crusting of the sheaths is not peeled off when the cable burns, the wire cores are effectively protected, and flame is prevented from continuing to burn.