Material structure of wires and cables
- PRODUCT DETAIL
The vast majority of wire and cable products are elongated products with the same cross-section (cross-section). This is due to the cross-sectional characteristics used as a circuit or coil in the system or processing equipment. Therefore, to study and analyze the structure of cable products, only need to observe and analyze from its cross section.
Structural features of wire and cable products:
In general, it can be divided into four main structural components: wire, insulating layer, shielding and protective layer, as well as filling elements and tensile elements. According to the use requirements and application occasions of the product, some product structures are extremely simple.
2. Cable material
In a sense, the wire and cable manufacturing industry is an industry of material finishing and assembly. First, the amount of materials used is huge, and the cost of materials in cable products accounts for 80-90% of the total manufacturing cost; The second is that there are many types and varieties of materials used, and the performance requirements are particularly high. If copper is used for the conductor, the purity of copper must be above 99.95%, and some products must use oxygen-free high-purity copper; Third, the selection of materials will have a decisive influence on the manufacturing process, product performance and service life. At the same time, the benefits of wire and cable manufacturing enterprises are closely related to whether materials can be scientifically saved in the selection, processing and production management of materials.
Therefore, the design of wire and cable products must be carried out at the same time as the selection of materials. Selection of several materials in general, determined by the process and after the screening test and performance.
The materials for cable products can be divided into conductive materials, insulating materials, filling materials, shielding materials, and protective layer materials according to their use parts and functions. But some of the materials are common to several structural parts. Especially thermoplastic materials, such as polyvinyl chloride, polyethylene, etc., can be used on insulation or sheaths as long as part of the formulation is changed.
The materials used in the manufacture of cable products involve a wide range of categories, and there are particularly many varieties and specifications (brands).
3. Name and material of product structure
(1) Wire: The most basic and essential component for the product to carry out electric current or electromagnetic wave information transmission function.
Main material: Wire is the abbreviation of conductive core, made of copper, aluminum, copper-clad steel, copper-clad aluminum and other non-ferrous metals with excellent conductivity, and optical fiber is used as the wire.
There are bare copper wires and tinned wires; Single branch wire, twisted wire; Tinned wire after twisting.
(2) Insulation layer:
It is a component that is wrapped around the periphery of the wire and plays an electrical insulation role. That is, it can ensure that the transmitted current, electromagnetic waves, and light waves only travel along the wires and do not flow to the outside. The potential on the conductor (that is, the potential difference formed on the surrounding objects, that is, the voltage) can be isolated.
That is to ensure the normal transmission function of the wire, but also to ensure the safety of external objects and people. Wire and insulation are the two basic components that must be equipped to form cable products (except bare wires).
Main materials: PVC, PE, XLPE, polypropylene PP, fluorine plastic F, rubber, paper, mica tape
(3) Filling structure:
Many wire and cable products are multi-core, and these insulated cores or wire pairs are cabled (or grouped and cabled multiple times). One is that the shape is not round, and the other is that there is a large gap between the insulated cores, so a filling structure must be added when the cable is formed. The filling structure is to make the outer diameter of the cable relatively round to facilitate the wrapping and squeezing of the sheath.
Main material: PP rope
(4) Shielding layer:
It is a material composition that isolates the electromagnetic field in the cable product from the external electromagnetic field; Some cable products also need to be isolated from each other between different wire pairs (or wire groups). It can be said that the shielding layer is a kind of "electromagnetic isolation screen". The conductor shielding and insulation shielding of high-voltage cables are used to homogenize the electric field distribution.
Main materials: bare copper wire, copper clad steel wire, tinned copper wire
(5) Protection layer:
When wire and cable products are installed and operated in a variety of different environments, they must have components that protect the entire product, especially the insulating layer, which is the protective layer.
Because insulating materials are required to have excellent various electrical insulating properties, it is necessary to require extremely high purity of the material and minimal impurity content; It is often unable to take into account its ability to protect the outside world, so it is resistant to various mechanical forces from the outside world (that is, installation, use and use), resistance to atmospheric environment, resistance to chemicals or oils, and prevention of biological damage . As well as reducing fire hazards, various protective layer structures must be undertaken.
Main materials: PVC, PE, rubber, aluminum, steel belt
(6) Tensile components: The typical structure is steel core aluminum stranded wire, fiber optic cable, etc. In short, tensile materials play a major role in the developed special small, flexible products that require multiple bending and twisting.
Main material: steel wire