The Research Of The Drawing Processes Based On Property Controlling Of TP2 Copper Tube

TP2 phosphorous deoxidize copper containing 0.015%~0.040% of P is the ideal material for fabricating tube, which has excellent thermal conductivity, diamagnetism and corrosion resistance. Drawing process with floating plug is the main method for tube production with higher efficiency and larger reduction. What’s more, it is not restricted by the pipe length during the production process. But it still needs to be further improvement for the purpose of high precision and quality.So it is necessary to research the drawing processes and make an appropriate adjustment to optimize the original processes. A series of research was carried on the drawing processes based on the tube of Φ9.52×0.75 mm.Firstly, the characteristics of drawing process with floating plug were analyzed. The drawing process was designed by using the method of double decline. It was finally confirmed combining with experienced values.Secondly, tensile tests at different temperatures were carried out. The results show that the yield strength of the tube decreases from 346 MPa to 84 MPa with the temperature increases from 20℃ to 500℃. And the elongation changed from 49.3% to 70.2%. The relationship between the mechanical properties and drawing reduction was eatablished.Thirdly, based on the soften and harden curves, the drawing process of tubes was simulated and optimized by the FEM software MSC.Marc. The results showed that the effect of the drawing speed to the precision and axial stress is the biggest in the same pass. Then it is the friction coefficient. The die cone angle was the smallest one. The optimal values are 2.6667 m/s, 0.05 and 13° respectively. In the triple drawing process, the temperature of each pass raised when the total drawing reduction increased from 72.92% to 75.95%. The axial stress during the former two passes increased with the increase of total drawing reduction, while it decreased instead.At last, the annealing experiments were carried out. At the same annealing time(1h), the strength and hardness of the tube decreased when the temperature increased from 200℃ to 600℃. The elongation increased with the increase of tmepreature. When the temperature reached 400℃, the mechanical properties and microstructure changed obviously because of the complete recrystallization. For the different annealing time, the mechanical properties and microstructure did not change obviously when the temperature was 300℃. When the temperature reached 400℃ and kept for 30 min, the mechanical properties and microstructure significantly changed. While at the temperature of 500℃, the strength and Vickers hardness changed a little, and the elongation increased evidently when the annealing time increased.