Tips for preventing oxidation of general rubber sheathed cable conductor

Author：hlyb Add Time：2016-03-03 16:06:59

The general rubber sheathed cable takes class 5 copper conductors as the conductive core. In its production process, oxidation and discoloration of copper conductors are often found, which seriously affects the quality of products and has become a difficult technical problem for many domestic cable manufacturers.

Copper is a transition metal, which is easily oxidized into black CuO by oxygen in the air under acidic conditions. When there is water film or water drop on the surface of copper conductor, due to a large amount of dust in the atmosphere, such as smoke, coal, automobile exhaust, chloride and other acid, alkali and salt particle dust, these harmful substances can be dissolved in water film or water drop to form electrolyte, so as to aggravate the oxidative discoloration of copper conductor. The light ones affect the appearance quality and product quality of products, and the heavy ones affect the use of copper conductors, resulting in waste of production costs. Therefore, copper conductors must be kept properly and pay attention to anti-oxidation and discoloration.

In principle, metallic copper for cable mainly includes physical methods to prevent copper from contacting with humid air, cathodic protection oxidation-reduction method to prevent copper conductor oxidation, chemical methods to form passive film on the surface of copper conductor to prevent oxidation, or spraying special liquid on the surface of conductor for protection. Taking the production of general rubber sheathed cable as an example, the main methods of anti-oxidation control in each process are introduced.

1. Transportation, inspection and storage of copper rod before entering the plant

Most of China's cable enterprises use copper as outsourcing, so high-quality metal copper rods shall be selected to standardize the supplier's transportation and delivery process and system. The incoming inspection of copper rods shall be carried out in accordance with GB / T 3048.2 or the enterprise standard of cable enterprises. The copper rod can be covered with plastic cloth or plastic film for storage, that is * * * simple physical barrier method to prevent the copper rod from contacting with humid air. When receiving copper rods, the workshop must visually check whether there is blackening one by one, and control it from the production source.

2. Control of copper rod drawing process

The drawing of 0.4mm monofilament generally adopts continuous annealing copper large drawing machine and medium drawing machine, which needs to go through the processes of setting out, drawing and annealing, cooling, drying, winding and so on. First of all, the appropriate mold should be selected and must not be too small, otherwise it will force the lattice variation of metal copper and aggravate the sharp rise of metal temperature. Secondly, check the pH of the emulsion before startup to ensure that it is alkaline solution. At the same time, antioxidant should be added to the drawing oil to form a passive film on the surface of copper conductor to prevent oxidation; During paying off, keep the paying off tension stable and uniform without excessive vibration; During wire drawing, the operator shall ensure proper water level, ensure uniform annealing degree and avoid insufficient or excessive annealing; During take-up, there should be no residual liquid on the surface of the copper conductor. A dry felt can be placed in front of the take-up (often replaced) to ensure the drying of the monofilament*** After drawing, seal the footwall with transparent plastic film and store it in a dry environment for circulation, otherwise it will be prone to oxidation with humid air due to the high surface temperature of the conductor.

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

Taking copper wire stranding as an example, during the stranding process of the conductor, the structure of the metal copper lattice is changed through each die. Under the action of strong external force, the temperature of the copper conductor after mold passing is greatly higher than that before mold passing, so the outer layer of the copper conductor is easy to oxidize. Therefore, the antioxidant (0.3% benzotriazole alcohol solution) can be dropped into the copper wire with the infusion hose during the twisting process. The dropping standard shall be subject to just infiltrating the surface of the copper wire, so as to avoid too little local oxidation or too much waste. The machine can be started up after all anti-oxidation work is well prepared. The take-up reel shall be dry at the take-up position. After the take-up reel is filled, it shall be sealed with transparent plastic film.

Before the conductor is extruded for insulation, the polyester tape shall be wrapped longitudinally or wrapped, and the substance in the rubber insulation material shall be placed to corrode the conductor. During the extrusion process of insulating rubber and sheath rubber, avoid water entering the wire head, resulting in oxidation and blackening of the wire head.

In our daily production observation, we found that by selecting high-quality copper rod, effectively controlling the drawing process and emulsion concentration and temperature, annealing process, passivation treatment of conductor stranded or bundle stranded copper wire surface and preventing water from entering the wire end, in addition, workshop operators should establish quality awareness and strengthen business training, so as to clearly understand the adverse consequences caused by copper wire oxidation, Strict quality control can effectively control the quality of cable copper conductor, prevent its oxidation, greatly improve work efficiency and reduce rework frequency, so as to achieve the beneficial effect of reducing cost and improving internal product quality.

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Tips for preventing oxidation of general rubber sheathed cable conductor