Overview of the wire and cable manufacturing process
The manufacturing of wire and cable is quite different from the way most electromechanical products are manufactured. Electromechanical products usually use the assembly of another part into a component, multiple parts and then assembled into a single product, and the product is measured in units or pieces. Wire and cable are measured in lengths as 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,, cable, sheathing, etc. and made of wire and cable products. The more complex the structure of the product, the more layers are superimposed.
A wire and cable products manufacturing process characteristics: 1:
1 large length continuous stacking combination of production methods
Large-length continuous stacking combination of production methods, the impact of wire and cable production is global and controlling, which involves and affects:
(1) production process and equipment layout
Production plant of various equipment must be discharged in accordance with the product requirements of the process flow is reasonable, so that each stage of the semi-finished products, in order to flow. Equipment configuration to consider the different production efficiency and the balance of production capacity, some equipment may have to be configured two or more, in order to make the production line production capacity to balance. Thus, the reasonable combination of equipment and the layout of the production site must be balanced according to the product and production volume to consider.
(2) Production organization and management
Production organization and management must be scientific and reasonable, thorough and accurate, strict and meticulous, the operator must be meticulous in accordance with the process requirements, any problem in any one link will affect the smooth flow of the process, affecting the quality and delivery of products. Especially for multi-core cables, if the length of a certain pair or basic unit is short, or if there is a problem with the quality, the whole cable will not be long enough, resulting in scrap. Conversely, if the length of a unit is too long, it must be sawed off resulting in waste.
(3) Quality control
The production method of continuous stacked combination of large lengths makes the production process a little problem in any one link, instantaneously, will affect the quality of the whole cable. The more quality defects occur in the inner layer, and not found in time to terminate production, then the greater the damage caused. Because the production of wire and cable is different from the assembled products, can be disassembled and reassembled and replaced with another piece; wire and cable of any part or process quality problems, the cable is almost irretrievable and irreparable. The aftermath of the treatment are very negative, either sawing short or downgrade treatment, or scrap the entire cable. It cannot be disassembled and reassembled.
The quality management of the wire and cable must be throughout the entire production process. Quality management inspection department to the entire production process tour inspection, operator self-inspection, up and down the process of mutual inspection, which is to ensure product quality, improve the economic efficiency of enterprises and an important guarantee and means.
2 production process more categories, material flow is large
Wire and cable manufacturing involves a wide range of processes, from the melting and pressure processing of non-ferrous metals, to plastics, rubber, paint and other chemical technology; fiber materials, such as wrapping, weaving and other textile technology, to metal materials, wrapping and metal strip longitudinal wrapping, welding metal forming and processing technology and so on.
Wire and cable manufacturing of various materials used, not only categories, varieties, specifications, and large quantities. Therefore, the amount of various materials, spare volume, batch cycle and batch must be approved. At the same time, the decomposition of scrap processing, recycling, reuse and waste disposal, as an important element of management, good material quota management, pay attention to saving work.
Wire and cable production, from raw materials and various auxiliary materials in and out, storage, the flow of semi-finished products in each process to the storage of products, factory, material flow, must be reasonable layout, dynamic management.
3. Special equipment
Wire and cable manufacturing using special production equipment with the characteristics of the industry process to adapt to the structure of cable products, performance requirements, to meet the requirements of continuous and high-speed production of large lengths, thus forming a series of special equipment for cable manufacturing. Such as extrusion machine series, wire drawing machine series, stranding machine series, wrapping machine series, etc..
Wire and cable manufacturing process and the development of special equipment are closely related and promote each other. New process requirements, 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 processes. Such as wire drawing, annealing, extrusion tandem line; physical foam production line and other special equipment to promote the development and improvement of wire and cable manufacturing process, improve the quality and production efficiency of cable products.
Second, the main process of wire and cable
Wire and cable is made by: pulling, stranding, wrapping three processes to complete, the more complex the model specifications, the higher the repeatability.
1. Pulling system
In the metal pressure processing. Under the action of external force to force the metal through the mold (pressure wheel), the metal cross-sectional area is compressed, and obtain the required cross-sectional area shape and size of the technical processing method is called metal drawing.
Drawing process is divided into: monofilament drawing and stranded drawing.
2 stranded system
In order to improve the softness of the wire and cable, the overall degree, so that more than 2 single wire, interwoven together in the specified direction called stranding.
Stranding process is divided into: conductor stranding, cable, braiding, wire armoring and winding.
3. Covering
According to the different performance requirements of the wire and cable, the use of special equipment outside the conductor wrapped with different materials. Cladding process is divided into:
A. Extrusion package: rubber, plastic, lead, aluminum and other materials.
B. Longitudinal package: rubber, wrinkled aluminum tape material.
C. Wrap: strip of paper tape, mica tape, alkali-free glass fiber tape, non-woven fabric, plastic tape, etc., line of cotton yarn, silk and other fiber materials.
D. Dip coating: insulation paint, asphalt, etc.
Third, the basic process of plastic wire and cable manufacturing
1 copper, aluminum monofilament drawing
Wire and cable commonly used copper, aluminum rod, at room temperature, the use of wire drawing machine through one or several stretching mold die hole, so that its cross-sectional reduction, length increase, strength increase. Wire drawing is the first process of each wire and cable company, the main process parameters of wire drawing is to match the die technology.
2. Monofilament annealing
Copper and aluminum monofilaments are heated to a certain temperature to recrystallize in order to improve the toughness and reduce the strength of monofilaments to meet the requirements of wire and cable for conductive cores. Annealing process is the key to eliminate the oxidation of copper wire.
3. Stranding of the conductor
In order to improve the softness of the wire and cable, in order to lay the installation, the conductive core to take multiple monofilament stranded. From the conductive core of the stranded form, can be divided into regular stranding and non-regular stranding. Irregular stranding is also divided into bundle stranding, concentric complex stranding, special stranding, etc..
In order to reduce the area occupied by the conductor, reduce the geometry of the cable, the stranded conductor while using the form of tight compression, so that the ordinary round variation into a semicircle, fan, tile and tightly pressed round. This kind of conductor is mainly used in power cables.
4. Insulation extrusion
Plastic wire and cable mainly uses extruded solid type insulation, plastic insulation extrusion of the main technical requirements:
4.1 Eccentricity: the deviation value of the extruded insulation thickness is an important symbol to reflect the level of extrusion process, most of the product structure size and its deviation value are clearly specified in the standard.
4.2 Smoothness: The surface of the extruded insulation layer must be smooth, and there must be no surface roughness, scorching or impurities of bad quality.
4.3 Density: the cross section of the extruded insulation layer should be dense and firm, no pinholes visible to the naked eye, and no bubbles should exist.
5. Cable formation
For multi-core cable in order to ensure the degree of molding, reduce the shape of the cable, generally need to be stranded in the round. Stranding mechanism is similar to the conductor stranding, due to the stranded node diameter is larger, most of the non-return twist method. The technical requirements of cable formation: First, to eliminate the twist of the cable caused by shaped insulation cores turning over; second, to prevent the insulation layer from being scratched.
Most of the cable in the cable along with the completion of two other processes: one is the filling, to ensure that the cable is rounded and stable; one is tied to ensure that the core is not loose.
6. Inner sheathing
In order to protect the insulated core from being lumped by the armor, the insulation layer needs to be properly protected, and the inner sheath is divided into: extruded inner sheath (isolation sleeve) and wrapped inner sheath (mat layer). Wrapping matting layer instead of tying tape and cable formation process are carried out simultaneously.
7、Armored
When the cable is laid underground, it may bear certain positive pressure during the work, and the inner steel belt armored structure can be chosen. When the cable is laid in the occasion of both positive pressure and tension (such as in water, vertical shaft or soil with large drop), the structure type with inner steel wire armor should be chosen.
8. Outer sheath
Outer sheath is to protect the insulation layer of wire and cable to prevent the erosion of environmental factors of the structural part. The main role of the outer sheath is to improve the mechanical strength of the wire and cable, chemical corrosion, moisture, water immersion, to prevent the ability of the cable burning. According to the different requirements of the cable using the extrusion machine directly extruded plastic sheath.