Due to the lattice stretching of the conductor during the drawing process, the conductor becomes hardened. After a certain temperature is heated, the softness required to restore the process after molecular lattice rearrangement is the purpose of the annealing. At the same time annealing process can remove the lubricant, oil on surface of the conductor during drawing. Make the conductor easy to paint, to ensure the quality of enameled wire. The most important thing is to ensure that the enameled wire has proper softness and elongation in the process of winding, and at the same time helps to improve the electrical conductivity.
The greater the degree of deformation of the conductor, the lower the elongation, the higher the tensile strength.
There are three commonly used methods to annealing copper wire: whole plate annealing; drawing machine continuous annealing; enameling machine continuous annealing. The first two methods can not meet the requirements of enamel process. The whole plate annealing can only make the copper soften, and cannot wipe out the oil completely. Because of the wire annealed soft, it makes the wire bending when despoiling. Although the copper can be achieved to soften and remove the surface of the grease in continuous annealing in the wire drawing machine, the soft copper wire winding to spool it bending a lot. Continuous annealing in enameling machine before painting not only achieves the purpose of softening and degreasing, but also the annealed wire is straight and directly enters the painting device to be coated with a uniform paint film.
Annealing furnace’s temperature is up to the length of the annealing furnace, copper wire specifications, line speed. At the same temperature and speed, the longer the annealing furnace, the more fully the recovery of the conductor lattice. In the lower annealing temperature, the higher the furnace temperature, the better the elongation, but when the annealing temperature is high, the opposite phenomenon occurs, the higher the temperature, the smaller the elongation, and the wire surface luster, and even easy to brittle .
If annealing furnace temperature is too high, it will not only affect the life of the furnace, but also parking finishing, when broken wire and thread wire will easily breakage wire. Requires the maximum annealing furnace temperature control at about 500 ℃. It is effective to select the temperature control point at the location where the static and dynamic temperatures are similar to the second stage temperature control mode of the furnace.
Copper is easily oxidized at high temperature, adn copper oxide is very crisp which make varnish film can not be firmly attached to the copper wire. Copper oxide film has a catalytic effect of aging, and has negative impact on the enamel wire flexibility, thermal shock, heat aging. In order to prevent copper wire to be oxidized, it is necessary to make the copper wire does not come into contact with oxygen in the air at high temperature, so there should be a protective gas. Most of the annealing furnace a water seal, the other open. Annealing furnace water tank has three functions: closed mouth, cooling wire, steam occurs as a protective gas. In beginning of turn-on machine that there is small amount of water vapor in annealing tube so that it can not remove the air in time. You can fill the annealing tube with a small amount of alcohol solution (1: 1). (Pay attention not to be irrigated pure alcohol and control the amount used)
The quality of the water in the water tank is very important. Impurities in the water can cause the wire to become unclean and affect the painting, making it impossible to form a smooth film. Use chlorine in the water should be less than 5mg / l, conductivity less than 50μΩ / cm. Chloride ions attached to the surface of the copper wire corrode the copper wire and the paint film over a period of time and produce black spots on the wire surface inside the paint wire. To ensure quality must clean sink regularly.
Water temperature in the tank is also required. High water temperature is conducive to the occurrence of water vapor on the annealing of copper wire protection, and make the wire waterless when wires go out the tank. But the wire cooling is not conducive. Although the low water temperature has played a cooling effect, the wire with a lot of water is not good to get the paint. Normally, the thick dimension use lower water temperature and the thin dimension use higher water temperature. When the copper wire to leave the water vapor splashed sound, indicating that the water temperature is too high. Generally big dimension wire controls at 50 ~ 60 ℃, mid dimension wire controsl at 60 ~ 70 ℃, small dimension wire controls at 70 ~ 80 ℃. Small dimension wire due to high speed with serious water problems that should adopt hot air drying.