Abstract
The drawing stress and the plug stress of the tube drawing were studied.
At first, the particular drawing process was analysed, where the wall thickness of tubes was reduced, the internal diameter being kept constant, and then the general tube drawing process was investigated where the tube diameter and the wall thickness were also reduced.
The latter case was assumed as a single plug drawing process under the back tension, induced by the drawing stress of initial sinking process.
But from the experimental results that the influence of the die angle on the drawing stress of thin wall tubes was smaller than that calculated from the above mentioned method, the author introduced the new "sec α type" term.
In case of sinking, other two additional terms were introduced, which were the functions of the die angle and the wall thickness.
In case of plug drawing, other 4 additional terms of the drawing stress were introduced, namely two terms for additional shear strain similar to sinking, the term for friction of die bearing and the term for resistance force from the plug which was introduced by the bending of metal flow at outlet of the die. The additional terms for the plug stress were the term for friction of die bearing and that of resistance force from the plug at outlet of the die.
