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ECCA Manufacturer Introduces Requirements for Annealing Process

Update:27-01-2020
Summary:

Annealing of enameled copper clad aluminum wire is the […]

Annealing of enameled copper clad aluminum wire is the same as that of copper wire, eliminating cold work hardening phenomenon after drawing, and softening twisted crystal lattice by recrystallization to restore regular arrangement. The following ECCA Manufacturer will specifically introduce its entire annealing process for you.

The annealing process of bimetallic conductor is obviously different from that of copper-aluminum single conductor. Annealing of copper wire at any point in the range of several hundred degrees above the recrystallization temperature to below the melting point will not cause quality accidents and is not very sensitive to temperature fluctuations. However, enameled copper clad aluminum wire has strict limits on furnace temperature, and the temperature difference between wire tubes must not be too different. The water-sealed copper wire annealing furnace with wire tubes as heating elements has different temperature field distribution of each wire tube after furnace temperature balance because it is a self-heating heat source. The raceway on the outer side of the furnace body is always lower than the tube temperature on the inner side, and the set furnace temperature is higher. The greater the temperature difference, it can reach more than 30℃. At the same time, the annealing performance of the conductors of the same specification are quite different. When the conductors of the conduits arranged in the middle are qualified, the wires of the outer two tubes are hard and cannot reach the elongation index.

In another case, the temperature of each wire tube is basically the same, and different results will appear when the wire speed is unchanged and the set furnace temperature is only 20℃ different from top to bottom: during the upper limit, the copper aluminum alloy layer will thicken quickly, the wire will become brittle, and the elongation rate will obviously decrease; Set at lower limit. Elongation rate of the conductor increases little and inconspicuously. This is enough to prove that the enameled copper-clad aluminum wire is very sensitive to temperature response and the range of furnace temperature set for annealing is narrow.

The annealing furnace temperature of enameled copper clad aluminum wire is generally controlled below 600℃, and the linear velocity depends on the size of the conductor section. Due to the low annealing temperature relative to copper wire, the amount of steam generated during cooling in the water inlet tank is small. Oxidation occurs from time to time. In order to increase the amount and density of steam, the temperature of the water tank should not be too low, and should generally be controlled at about 70℃. At the same time, the conductor sleeve at the wire inlet end must be sleeved on the bobbin to reduce the cross-section of the steam outlet, relieve the passivity of the steam at the inlet, make the conductor in a stable preheating state, and improve the softening effect.