Copper and aluminum monofilament drawing
The copper and aluminum rods commonly used for wire and cable are drawn at a normal temperature by a drawing machine through one or several rows of die holes of the die so that the cross-section is reduced, the length is increased, and the strength is improved. Drawing is the first process of wire and cable companies.
Copper and aluminum monofilaments are heated to a certain temperature to recrystallize 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 copper wire.
Stranding of conductors
In order to improve the softness of the wire and cable, and in order to facilitate the installation and installation, the conductive core is formed by stranding a plurality of monofilaments. From the twisted form of the conductive core, it can be divided into regular stranding and irregular stranding. Irregular stranding is further divided into bunching, concentric twisting, special stranding, and the like.
In order to reduce the occupied area of the wire and reduce the geometrical size of the cable, the twisted form is used while twisting the conductor, so that the ordinary circular variation is a semicircle, a fan shape, a tile shape and a compact circular shape. This type of conductor is mainly used on power cables.
Plastic wire and cable mainly adopt solid insulation type with extruded rubber. The main technical requirements for plastic insulation extrusion are:
Eccentricity: The deviation of the insulation thickness of the extrusion is an important indicator of the level of the extrusion process. Most of the product structure dimensions and their deviation values are clearly defined in the standard.
Smoothness: The surface of the extruded insulation layer is required to be smooth, and no bad quality problems such as surface roughness, scorch, and impurities may occur.
Density: The cross-section of the extruded insulation layer should be dense and firm, and pinholes visible to the naked eye should not be allowed to prevent the presence of air bubbles.
For multi-core cables, in order to ensure the degree of moulding and reduce the shape of the cable, it is generally required to be twisted into a circular shape. The mechanism of stranding is similar to that of conductor stranding. Due to the large diameter of the stranding, most of the methods are not back-twisted. The technical requirements for cable-forming: First, to prevent the twisted corner of the cable caused by the turned-over insulated core, and the second is to prevent the insulation layer from being scratched.
Most of the cables are cabled along with the completion of two other processes: one is filling, which is to ensure roundness and stability of the cable after the cable is formed; one is trying to ensure that the cable core is not loose.