Causes of copper wire blackening

2020-07-17

The reasons for the blackening of copper wires compiled by the editor:
1. The area of the drawing emulsion oil pool is small, the return pipeline is short, and it is sealed, resulting in slow heat dissipation and high emulsion oil temperature.
2. It is caused by copper wire annealing.
① The cooling water used for continuous cooling is usually tap water and groundwater. Due to the varying water quality in different regions, the pH value of water in some areas is low, only 5.5-5.0 (normally 7.0-7.5). The antioxidant oil film in the original emulsion has been cleaned, and the annealed copper wire is prone to oxidation and blackening;
② The finished copper wire drawn by an ordinary wire drawing machine is annealed on another annealing line, and the cooling water does not use antioxidants. The oxidation resistance time is short, and oxidation and blackening phenomenon will soon occur;

3. Some old factories still use annealing cylinders for annealing, which can also cause oxidation and blackening due to the following reasons:
① The annealing cylinder nut was not tightened and leaked after flushing carbon dioxide or high-purity nitrogen;
② When the temperature of the copper wire discharged from the cylinder is too high, exceeding 30 ℃;
③ Insufficient maintenance of wire drawing emulsion, low pH value;
These situations are more common in summer when the temperature is high, and the emulsion will be lost if used continuously. When the temperature is high, the loss is faster. If new crude oil is not replenished in time, the fat content is very low. In addition, the temperature of the emulsion may exceed 45 ℃, which is easy to cause oxidation and blackening.
　　
4. Another situation is that due to the widespread use of high-speed wire drawing, its speed has increased and the relative heat dissipation time has decreased, bringing a certain amount of space and time to oxidation.
Therefore, it is suggested that the manufacturer should pay more attention to the fat content of the lotion, whether the use temperature and PH value are appropriate. In the yellow and rainy season of spring, bacteria multiply rapidly, so bactericides and mildew inhibitors can be used, and in summer, antioxidants can be used to solve the oxidation and blackening problems.
　　
Reason
1. The deformation of the finished mold is too small;
2. The periphery and front of the mold insert are not properly sealed.
Solution
Add a rubber pad in the outlet direction of the finished mold, and then press the thread onto the finished mold to solve the problem of oil leakage.
The deformation of the finished mold is too small, which is a common mistake. Single mold deformation requires a minimum deformation amount to generate pressure that is greater than the yield limit of the metal, in order to achieve plastic deformation, stable size, and the light generated by cold drawing on the surface of the single line.