Analysis of the annealing process of copper-clad aluminum wire

he annealing process of copper-clad aluminum wire The annealing process of copper-clad aluminum wire is the same as copper wire, which eliminates the cold work hardening phenomenon after drawing and makes the distorted crystal The lattice is softened by recrystallization to restore the regular arrangement However, the annealing process of bimetallic conductors is significantly different from the annealing of copper-aluminum single-quality conductors. Copper wire annealing at any point in the range of several hundred degrees from the recrystallization temperature to below the melting point will not cause quality. accidents, and is not very sensitive to temperature fluctuations; while copper-clad aluminum wire has stricter restrictions on furnace temperature. The temperature difference between the line pipes must not be too large.The water-sealed copper wire annealing furnace that uses the wiring tube as the heating element, because it is a self-heating heat source, the temperature field distribution of each wiring tube is Different after the furnace temperature is balanced. Recently, the wiring pipe on the outside of the furnace body is always lower than the pipe temperature on the inside, and the higher the furnace temperature is set.

The greater the temperature difference, it can reach more than 30 ° C. At the same time, the annealing performance of the conductors of the same specification is very different. When the conductors of the wiring tubes arranged in the middle are qualified, the wires In another case, the temperature of each wire tube is basically the same, the wire speed is unchanged, and the set furnace temperature is only 20 ° C between the upper and lower sides, different results will occur: at the upper limit, the copper -aluminum alloy layer This is enough to prove that the copper clad aluminum wire is very sensitive. This is enough to prove that the copper clad aluminum wire is very fast Thicker, the wire becomes brittle, and the elongation is obviously reduced; -clad and drawing process,Due to the extrusion force and the temperature generated by the plastic deformation, the copper-clad aluminum wire has formed about \ u0026lt; 0.01 mm thick copper-aluminum on the bimetal interface. Eutectic alloy layer. The melting point of the alloy is 548 ° C, which is lower than the melting points of the two elemental metals.

The annealing of copper Polyesterimide Enameled Aluminum Round Wire and aluminum It seems safer. In order to increase the bonding strength of the copper-aluminum interface, the thickness of the alloy layer must be appropriately thickened. It seems safer. In order to increase the bonding However, when the furnace temperature exceeds the melting point of the alloy, the conductor should not stay in the wiring tube for too long, otherwise it will cause. The alloy layer to thicken too much, And severely cause the copper clad aluminum wire to melt Whether the conductor is softened or not depends on whether the bimetal has reached the recrystallization temperature. This is directly related to the reasonable determination of process parameters. The recrystallization temperature of aluminum is 100 ° C, copper is 270 ° C,and the eutectic temperature of copper-aluminum alloy is 548 ° C. Therefore, in actual operation, the furnace temperature is often set at: 550 ° C to 600 ° C, and the conductor Each point of the circular cross section can reach the recrystallization temperature, and there must be a certain amount of heat transfer time.and there must be a certain amount of heat transfer time.and there must be a certain amount of heat transfer time.and there must be a certain amount of heat transfer time.and there must be a certain amount of heat transfer time.

The thermal conductivity of the two metals is different, copper is 0.923 cal / cm \ u0026middot; s \ u0026middot; C, aluminum is 0.52 cal / cm \ u0026middot; s \ u0026middot; C, the heat transfer speed of copper is almost l times faster than that of aluminum, and copper is on the outside aluminum is in the core, and heat is transferred from the outside to the core layer. Therefore, the wire routing speed (also the time in the furnace tube) is usually half of the Copper wire of the same cross-section. The annealing furnace temperature of copper clad aluminum wire is generally controlled below 600 ° C, and the wire speed depends on the size of the conductor section. Due to the lower annealing temperature of copper wire, less steam is generated when the water inlet tank is cooled. Oxidation phenomenon occurs from time to time.In order to increase the amount of steam and increase the density of steam, the temperature of the water tank should not be too low, generally should be controlled at about 70 ° C; at the same time, the conductor sleeve of the inlet end must be sleeved on the wiring pipe to reduce The cross section of the water vapor outlet relieves the passiveness of the steam at the inlet, keeps the conductor in a stable preheating state, and improves the softening effect.keeps the conductor in a stable preheating state, and improves the softening effect.keeps the conductor in a stable preheating state, and improves the softening effect.