1. Annealing process:
The annealing method is generally an electrical contact type. The electrode introduces a large current into the copper wire uniformly through the annealing wheel (contact wheel) to realize the preheating and heating of the copper wire. Preheating is to heat the copper wire to the highest temperature that will not be oxidized. It is about 250 degrees; heating is to heat the copper wire to the annealing temperature, generally 500 to 550 degrees, to make it recrystallize. The heating section has steam protection to prevent the copper wire from oxidizing. After cooling with water, the annealing (softening) is completed process.
2. Technical requirements:
1. Annealing voltage, wire drawing speed and wire take-up speed should be synchronized.
2. The annealing current is proportional to the square of the annealing wire diameter. The annealing current should be set according to the wire diameter. Ensure that the performance of the annealed soft copper wire meets the requirements of GB3953 or the ideal performance.
3. The take-up tension is adjusted by the pressure of the accumulator cylinder.
4. The diameter deviation of the copper wire should meet the requirements of GB3953.
3. Reasons for the reduction of wire diameter:
The copper wire is hardened during the drawing process. After annealing and softening, the tensile strength of the copper wire is reduced, and the plasticity and elongation of the copper wire are increased. Under the action of the wire tension, the reduction of the wire diameter is an inevitable phenomenon. However, the reduction of the wire diameter should be controlled. The range is generally not more than 0.02mm (determined according to the size of the wire diameter). If the wire tension is reduced, the copper wire between the annealing wheels will jitter, the contact is not good, there will be sparks, and it is easy to break and accelerate annealing. Damage to the wheel. Therefore, the wire tension should be selected according to the wire diameter.
Increase the amount of wire diameter reduction to the diameter of the sizing mold