The main methods of anti-oxidation of rubber sheathed cable conductors

Copper is the main raw material of the cable industry, but it is easily oxidized to black CuO by oxygen in the air under acidic conditions. Exhaust gas, chloride and other acids, alkalis, salt particles and dust, etc., these harmful substances dissolve in water film or water droplets to form electrolyte, which intensifies the oxidation and discoloration of copper conductors.

The general rubber sheathed cable uses Category 5 copper conductors as the conductive cores. During the production process, it is often found that the copper conductors are oxidized and discolored, which seriously affects the quality of the products and has become a long-standing technical problem for many domestic cable manufacturers. . Below, Zhujiang Cable takes the production of general rubber sheathed cables as an example, how to prevent the oxidation of rubber sheathed cable conductors.

1. Transportation, testing and storage of copper rods before entering the factory

Most cable companies in my country should choose high-quality metal copper rods for copper, and standardize the supplier's transportation and delivery process and system. The storage of copper rods can cover the copper rods with plastic cloth or plastic film, and use a simple physical barrier method to prevent the copper rods from contacting with moist air. When receiving copper rods in the workshop, it is necessary to visually check whether there is any blackening phenomenon one by one, and control them from the source of production.

2. Control of copper rod drawing process

The drawing of 0.4mm monofilament generally adopts continuous annealing copper large drawing machine and small drawing machine, which needs to go through the processes of pay-off, wire drawing and annealing, cooling, drying, and wire take-up. First of all, a suitable mold should be selected, and it must not be too small, otherwise the lattice of the metal copper will be forced to mutate, which will aggravate the sharp rise of the metal temperature. Secondly, check the pH of the emulsion before starting the machine to ensure that it is an alkaline solution. At the same time, antioxidants should be added to the drawing oil to form a passivation film on the surface of the copper conductor to prevent oxidation; when paying off, keep the pay-off tension stable and uniform. Excessive chattering; during the wire drawing process, the operator should ensure the proper water level to ensure uniform annealing degree, and avoid insufficient annealing or excessive annealing; when taking up the wire, there should be no residual liquid on the surface of the copper conductor, and a piece of dry felt can be placed in front of the wire take-up (replace frequently) to keep the monofilament dry. Finally, after drawing the bottom plate, it is sealed with a transparent plastic film, and stored in a dry environment until it is circulated, otherwise there will be a risk of oxidation with the humid air due to the high temperature of the conductor surface.

3. Copper wire stranding (strand stranding) and extrusion process of insulating rubber and sheath rubber

Taking copper wire twisting as an example, during the twisting process of the conductor, the metal copper lattice changes its structure through various compression dies. The outer layer of the copper conductor is easily oxidized. Therefore, the antioxidant can be dripped into the copper wire with an infusion hose during the twisting process. After the oxidation work is ready, start the machine again. Make sure that the take-up reel is dry at the take-up location, and after the take-up reel is full, seal it with a transparent plastic film.

Before the conductor is extruded and insulated, the polyester tape should be longitudinally wrapped or wrapped, and the substances in the rubber insulating material should be placed to corrode the conductor. During the extrusion process of insulating rubber and sheath rubber, water should be prevented from entering the thread, which may cause the thread to oxidize and turn black. In our daily production observations, we found that by selecting copper rods, effectively controlling the wire drawing process and the concentration and temperature of the emulsion, annealing process, passivation treatment of the surface of conductor stranded or bundled copper wires, and preventing the wire head from entering water, etc. In addition, workshop operators should establish quality awareness, strengthen business training, clearly recognize the adverse consequences of copper wire oxidation, and strictly control the quality, in order to effectively control the quality of cable copper conductors, prevent their oxidation, and greatly improve Improve work efficiency and reduce the frequency of rework, so as to achieve the beneficial effects of reducing costs and improving internal product quality.