Abstract:With the intensification of market competition, air-conditioning manufacturers have set strict requirements on the quality of copper pipes, especially surface defects. Intrusion of impurity is the most common surface defect in the drawing process of copper tubes. This defect will reduce the quality of copper tubes during the drawing process and even cause the copper tubes to break and be scrapped. By tracking the drawing process of the copper tube and analyzing the morphology and composition of the impurity pressed place, the results show that after three passes of drawing, impurities are pressed into the inner and outer surfaces of the copper tube, which leads to the occurrence of broken tubes. The main reason for the impurity intrusion defects in the drawing process of copper tube is the intrusion of external impurities, such as iron, silicon, oxygen and foreign particles, and the indentation points of these impurities form crack source and gradually expand under the action of tensile force, eventually leading to broken tubes in the drawing process of copper tubes. Through the control of copper raw material composition, the control of oxygen content in the melting and casting billets and the control of environmental cleanness in the melting and casting, rolling and disc drawing processes, the occurrence of such defects can be effectively reduced, further improving the quality of product.