RU2713640C1 - Insulating screening sheath - Google Patents

Abstract

FIELD: manufacturing technology.

SUBSTANCE: double-layer insulating screening sheath (web) is intended for electromagnetic and electrostatic shielding of wires, cables and bundles used during installation of onboard cable networks of aircrafts in aviation and space equipment. Inner layer is made of heat-resistant polyimide thread wound with metal thread, and outer layer is made of non-stretch textured heat-resistant polyimide thread. Outer layer is made of one or more interweaved inextensible textured polyimide yarns. Several pairs of non-stretchable inextensible textured polyimide fibers are woven into a belt or a web.

EFFECT: shell has low specific weight, high mechanical characteristics, primarily abrasive loads, is resistant to radiation and other radiation, liquid fuel, oil products, oils, acids, etc.

5 cl

Description

Technical field

The invention relates to the development of complex insulating shielding shells (braids) having a number of specific properties: low specific gravity, the ability to absorb, reflect or scatter electromagnetic radiation, resistance to high temperatures, open flame, manufacturability in the manufacture and installation, high mechanical characteristics, First of all, to abrasive loads, resistance to biological and climatic factors. Shell designs are based on an adjustable combination of organic fibrous materials with electrically conductive metal materials (thin and ultra-thin wire, flattening). Sheaths (braids) are designed for electromagnetic and electrostatic shielding of wires, cables and bundles used in the installation of aircraft cable networks in aircraft and space technology.

State of the art

A number of shielding insulating shells and braids (or methods for their manufacture) are known, consisting mainly of metal or tinsel threads, designed to improve the shielding of wires and cables from external electromagnetic influences, protecting cable networks from mechanical damage, high and low temperatures, which enable functioning products in confined spaces, the conditions of various climatic and energy fields.

A method for the manufacture of an insulating-shielding sheath of an electric wire or cable (patent RU 2299484 C1, IPC НВВ 7/18, publ. 05.20.2007), including the production of twisted threads by winding at least one metal shielding wire (copper or bronze, or from bimetal, or from aluminum-magnesium alloy, or from aluminum, clad with copper, with an anticorrosive coating, round or in the form of a flatten with a diameter or thickness, respectively 0.05-0.08 mm) on a reinforcing base of non-metallic fibers and weaving about balls of twisted yarns followed by removal (dissolution) of non-metallic fibers from the reinforcing base of twisted yarns woven into the sheath. The disadvantages of this method include the uneven surface density of the shielding shell resulting from the removal of the reinforcing component, which does not provide the shell with a sufficient degree of stability of the shielding, mechanical and thermophysical properties. The impossibility of creating a uniform density of the surface of the shell is also due to the interpenetration of the winding of adjacent twisted threads and the formation of hooks, leading to breakage of the threads. Another disadvantage of this method is the low mechanical strength of individual twisted threads, leading to low mechanical strength of the entire shielding. A serious disadvantage of the proposed method is the need for solvent return, recovery of the soluble auxiliary product or its environmentally friendly disposal.

A shielding braid was developed (utility model RU 101859 U1, IPC НВВ 11/06, published on January 27, 2011), in which a metal wire (mainly made of copper coated with silver, bronze coated with silver or aluminum, layered with zinc, copper and silver) the diameter of 0.03-0.12 mm braids carrier - a hollow tube or a cylindrical rod of a certain constant diameter of polymeric materials. This braid is made in one or more layers of homogeneous or dissimilar materials. The use of a second or more layer of metal wire leads to difficulties in the manufacture and high weight of the braid.

In the patent for utility model RU 151150 U1, IPC Н05К 9/00, publ. 03/20/2015, a shielding braid is presented in which the strands of the first direction of the wire are made of composite metal wires, and the strands of the opposite direction are made of another material (metal materials, as well as plastic polymeric materials, natural or synthetic threads), and strands of different directions can be of different thicknesses, and the metal coating of strands of any direction with a thickness of 0.003 mm or more is made of silver, nickel, tin or tin-lead solder. However, the use of this braid does not always give the necessary shielding characteristics, since the conductive strands in such braids are exactly half and the electrical conductivity is often insufficient for effective shielding, or there is no necessary sufficient resistance to mechanical stress, shock, abrasion, bending, as strands of metal wires not protected from possible mechanical damage.

Known insulating-shielding sheath (utility model RU 47568 U1, IPC НВВ 7/17, publ. 08/27/2005) with a reinforcing base of basalt fibers, entwined with a shielding metal wire of copper or bronze or with a copper sheath with an anticorrosive coating, round or in the form of a flatten with a diameter or thickness of 0.05-0.08 mm, respectively. However, basalt threads have high weight characteristics and are fragile and brittle with subsequent release of dust, which has a fibrogenic effect on humans, which is especially unacceptable in confined spaces and especially weightlessness.

The material described in the patent for utility model RU 168930 U1, IPC Н01В 9/02, Н05K 9/00, publ. 02/28/2017, is a protective braid obtained by interlacing plastic or synthetic or glass filaments with and without metal coating at a crossing angle of 30 ° to 80 °, while strands of different directions can be made of different materials and different thicknesses. The specified braid is worn over metal braids to protect against mechanical stress, high and low temperatures without a noticeable increase in weight. The proposed solution carries with it both ergonomic and operational flaws. Lack of ergonomics is associated with the difficulty of mechanically “dressing” the finished outer shell on the shielding, especially for very long structures. Also, due to “dressing”, the extension of metal wires of the inner shielding shell is almost inevitable, leading to a decrease in the effectiveness of electromagnetic protection.

Known shielding insulating sheath (patent RU 2270489 C2, IPC НВВ 7/18, НВВ 7/02, НВВ 9/02, НВВ 3/48, publ. 02.20.2006), light and flexible, with increased electrical insulation, mechanical and thermal characteristics, resistant to open flames, high temperatures up to + 600 ° С, acids, oil products, organic solvents, microbiological influences. The insulating shell consists of threads of different composition twisted together, one of the threads is made of arimide fiber and is the reinforcing base, and the second is made in the form of a metal thread with a thickness of 0.018-0.020 mm with and without coating and is a screening element. However, there is a high probability of sliding the shell and exposing the protected product.

The closest analogue (prototype) of the invention is a shielding insulating sheath (patent RU 2662446 C1, IPC НВВ 11/06, publ. July 26, 2018) lightweight, flexible, technologically advanced in the manufacture and installation, able to effectively protect a functional product (wire or cable) both from external electromagnetic effects and from external adverse factors (elevated temperatures, open flames, abrasive loads, mechanical damage, biological and climatic factors). The shell is made of two layers of different composition of threads. The first layer of the sheath (inner) is made of a heat-resistant polyimide thread entwined with a round or rolled metal thread. The metal thread is made with a diameter or thickness of 0.015-0.020 mm in its pure form or with a coating and is a shielding element. Polyimide yarn is a reinforcing base and is made of multifilament yarns of linear density from 3 to 100 tex. Polyimide yarns entwined with metal yarns are built together and woven into a ribbon or woven into a fabric. The second layer of the sheath (outer) is made of heat-resistant polyimide yarn of linear density from 3 to 100 tex. The outer layer may be made of single polyimide filaments or at least two polyimide filaments mated between each other. Several pairs of polyimide filaments woven together are woven into a ribbon or woven into a fabric. However, the high smoothness of the multifilament yarns contributes to the opening of the ends of the outer layer and the appearance of a sliding of the second (outer) layer of the sheath, which can lead to a decrease in heat-shielding properties and create difficulties during installation.

Disclosure of Invention

The aim of this invention is to provide a comprehensive lightweight and flexible, with improved electrical insulating, heat-shielding properties, resistant to blooming and sliding, as well as technological in the manufacture and installation of an insulating shielding sheath, which can effectively protect a functional product (wire or cable) from external electromagnetic effects, and from external adverse factors (elevated temperatures, open flames, abrasive loads, mechanical damage, radiation, organic FIR and inorganic liquids, biological and climatic factors).

This goal is achieved due to the fact that in the known two-layer shielding insulating sheath, the second (outer) layer is made of inextensible textured heat-resistant polyimide yarn of linear density from 6 to 100 tex.

The outer layer may be made of single inextensible textured polyimide yarns or at least two inextensible textured polyimide yarns milled together.

Several pairs of inextensible inextensible textured polyimide yarns woven together are woven into a ribbon or woven into a fabric.

Inextensible textured polyimide thread allows you to get a high-volume outer layer of the shell with high density coating. This design improves the heat-shielding properties of the shell. The increased roughness of the textured polyimide yarns provides adhesion between the yarns in the manufacture of the second layer, the absence of sliding of the yarns in the sheath and the resistance of the sheath ends to bloom.

The implementation of the invention

The shielding sheath - the first inner layer - is fed to a braiding machine, where its outer surface is braided with a second outer layer of one inextensible textured polyimide yarn or from inextensible inextensible textured polyimide yarns.

The complex insulating shielding sheath with increased coating density has increased electrical insulating, heat-shielding properties, is resistant to sliding and dissolving during installation and mechanical stress, resistant to radiation and other radiation, liquid fuel, oil products, oils, acids, organic solvents, microbiological influences, has a low coefficient of thermal conductivity, withstands open flame and heat shock with a temperature of + 600 ° C, and due to the second layer - up to + 900 ° C.

Claims (5)

1. A two-layer insulating shielding sheath made of threads of different composition, where the first layer (inner) is made of thermo-resistant polyimide yarn entwined with metal thread, characterized in that the second layer (external) is made of inextensible textured heat-resistant polyimide yarn of linear density from 6 up to 100 tex. 2. The insulating shielding sheath according to claim 1, characterized in that the outer layer is made of one or at least two inextensible textured polyimide yarns that are chopped together. 3. An insulating shielding sheath according to claim 1 or 2, characterized in that it contains several pairs of inextensible inextensible textured polyimide filaments mated together. 4. The insulating shielding sheath according to any one of paragraphs. 1-3, characterized in that several pairs of chopped inextensible inextensible textured polyimide yarns are woven into a ribbon. 5. The insulating shielding sheath according to claim 4, characterized in that several pairs of inextensible inextensible textured polyimide filaments woven together are woven into a fabric.