The manufacture of wire and cable is completely different from the production method of most electromechanical products. Mechanical and electrical products are usually assembled into parts, multiple parts and then assembled into a single product, the product is measured by the number of units or pieces. Wire and cable is based on the length of the basic unit of measurement. All wire and cable are from the conductor processing, in the periphery of the conductor layer by layer plus insulation, shielding, into the cable, sheath, etc. to make wire and cable products. The more complex the product structure, the more levels of superposition.
1. wire and cable products manufacturing process characteristics:
1. Large length continuous superposition combination production mode
Large-length continuous superposition combination production mode, the impact on the production of wire and cable is global and controlled, which involves and affects:
(1) Production process and equipment layout
All kinds of equipment in the production workshop must be reasonably discharged according to the process flow required by the product, so that the semi-finished products at each stage can be circulated in sequence. Equipment configuration to consider the production efficiency of different production capacity balance, some equipment may have to configure two or more, in order to balance the production capacity of the production line. Therefore, the reasonable matching combination of equipment and the layout of the production site must be balanced and considered according to the product and production volume.
(2) Production organization management
Production organization and management must be scientific and reasonable, careful and accurate, strict and meticulous, the operator must be meticulous in accordance with the requirements of the process, any link problems, will affect the smooth process, affect the quality of the product and delivery. Especially for multi-core cables, if the length of a certain wire pair or basic unit is short, or if there is a quality problem, the whole cable will not be long enough, resulting in scrap. Conversely, if a cell length is too long, it must be sawed away to waste.
(3) Quality management
The production method of large-length continuous superposition combination makes any link in the production process, and a little problem occurs instantaneously, which will affect the quality of the entire cable. The more quality defects occur in the inner layer, and the production is not found in time, the greater the loss. Because the production of wire and cable is different from the assembled product, it can be disassembled, reassembled and replaced; the quality problem of any part or process of wire and cable is almost irreparable to this cable. The treatment afterwards is very negative, either sawing or degrading, or scrapping the entire cable. It cannot be disassembled and reassembled.
The quality management of wire and cable must run through the entire production process. The quality management inspection department should inspect the whole production process, self-inspection of operators, and mutual inspection of upper and lower processes, which is an important guarantee and means to ensure product quality and improve the economic benefits of enterprises.
2. There are many types of production processes and large material flow
Wire and cable manufacturing involves a wide range of processes, from smelting and pressure processing of non-ferrous metals to chemical technologies such as plastics, rubber and paint. Textile technology such as winding and weaving of fiber materials, metal forming process of winding and longitudinal wrapping and welding of metal strips, etc.
The various materials used in the manufacture of wires and cables are not only of many types, varieties and specifications, but also of large quantities. Therefore, the amount of various materials, standby, batch cycle and batch must be approved. At the same time, the decomposition of waste treatment, recycling, reuse and waste disposal, as an important part of management, do a good job of material quota management, pay attention to conservation work.
In the production of wire and cable, from the entry and exit and storage of raw materials and various auxiliary materials, the flow of semi-finished products in each process to the storage and delivery of products, the material flow is large, and reasonable layout and dynamic management are necessary.
3. Special equipment
Wire and cable manufacturing uses special production equipment with the characteristics of the industry process to adapt to the structure and performance requirements of cable products, to meet the requirements of large length continuous and high-speed production as much as possible, thus forming a series of special equipment for cable manufacturing. Such as extrusion machine series, drawing machine series, stranding machine series, winding machine series, etc.
The manufacturing process of wire and cable is closely related to the development of special equipment and promotes each other. New process requirements, to promote the generation and development of new special equipment; in turn, the development of new special equipment, and improve the promotion and application of new technology. Such as wire drawing, annealing, extrusion series line; physical foaming production line and other special equipment, promote the development and improvement of wire and cable manufacturing process, improve the product quality and production efficiency of the cable.
Main process of 2. wire and cable
Wire and cable is made through three processes: drawing, twisting and cladding. The more complex the model and specification, the higher the repeatability.
1. Pull
In metal pressure processing. Under the action of external force, the metal is forced through the mold (pressure wheel), the cross-sectional area of the metal is compressed, and the required cross-sectional area shape and size of the technical processing method is called metal drawing.
The drawing process is divided into monofilament drawing and stranded drawing.
2. Stranding
In order to improve the softness of the wire and cable, the overall degree, so that more than 2 single wire, according to the specified direction of intertwined together called twisted.
Stranding process: conductor stranding, cable, weaving, wire armored and winding.
3. Covering
According to the different performance requirements of wires and cables, special equipment is used to cover different materials on the outside of the conductor. Cladding process:
A. extruded package: rubber, plastic, lead, aluminum and other materials.
B. longitudinal package: rubber, wrinkle aluminum belt material.
C. Winding: ribbon-shaped paper tape, mica tape, alkali-free glass fiber tape, non-woven fabric, plastic tape, etc., linear cotton yarn, silk and other fiber materials.
D. Dip coating: insulating paint, asphalt, etc.
The basic process of 3. plastic wire and cable manufacturing
1. Copper, aluminum single wire drawing
Wire and cable commonly used copper, aluminum rod, at room temperature, the use of wire drawing machine through one or several stretching die hole, so that its cross-section is reduced, the length is increased, the strength is improved. Wire drawing is the first process of wire and cable companies, and the main process parameters of wire drawing are mold matching technology.
2. Monofilament annealing
Copper and aluminum monofilaments are heated to a certain temperature to recrystallize to improve the toughness of the monofilament and reduce the strength of the monofilament to meet the requirements of the wire and cable for the conductive core. The key to the annealing process is to prevent the oxidation of the copper wire.
3. Stranding of conductors
In order to improve the softness of the wire and cable to facilitate the laying and installation, the conductive wire core is made of a plurality of monofilaments. From the stranding form of the conductive core, it can be divided into regular stranding and irregular stranding. Non-regular stranding is divided into bundle stranding, concentric complex stranding, special stranding and so on.
In order to reduce the occupation area of the conductor and reduce the geometric size of the cable, the conductor is twisted and the form of tight compression is used at the same time, so that the ordinary circle is transformed into a semicircle, a sector, a tile shape and a tight compression circle. Such conductors are mainly used in power cables.
4. Insulation extrusion
Plastic wire and cable mainly adopts extruded solid insulation, plastic insulation extrusion of the main technical requirements:
4.1. Eccentricity: The deviation value of the extruded insulation thickness is an important symbol of the extrusion process level, and most of the product structure dimensions and their deviation values are clearly defined in the standard.
4.2. Smoothness: The surface of the extruded insulating layer shall be smooth, and there shall be no poor quality problems such as rough surface, charring and impurities.
4.3. Density: The cross section of the extruded insulating layer should be dense and strong, with no visible pinholes and no bubbles.
5. Cable
For multi-core cables, in order to ensure the molding degree and reduce the shape of the cable, it is generally necessary to twist it into a round shape. The mechanism of stranding is similar to that of conductor stranding. Due to the large diameter of stranding section, most of them adopt the non-back-twisting method. The technical requirements for cable formation are: first, to prevent the twisting of the cable caused by the turning of the profiled insulated core; The second is to prevent the insulation layer from being scratched.
Most of the cables are completed with two other processes at the same time: one is filling to ensure the roundness and stability of the cables after the cable is completed; One is binding to ensure that the cable core is not loose.
6. Inner sheath
In order to protect the insulated wire core from being injured by the armor, the insulation layer needs to be properly protected. The inner sheath is divided into extruded inner sheath (isolation sleeve) and wrapped inner sheath (cushion). Winding the cushion layer instead of the binding tape is carried out simultaneously with the cabling process.
7. Armored
Laying in the underground cable, the work may bear a certain positive pressure, can choose the inner steel belt armored structure. Cable laying in both positive pressure and tensile role of the occasion (such as water, vertical shaft or large drop in the soil), should be selected with inner steel wire armor structure.
8. Outer sheath
The outer sheath is a structural part that protects the insulating layer of the wire and cable from environmental factors. The main function of the outer sheath is to improve the mechanical strength of the wire and cable, prevent chemical corrosion, moisture-proof, waterproof immersion, and prevent the cable from burning. According to the different requirements of the cable, the plastic sheath is directly extruded by the extruder.