ABOUT THE MEAN FRICTION REVERSAL DURING THE TUBES DRAWING WITHOUT INSIDE GUARD

The paper presents the possibility of the reduction of the drawing mean force and in the same time, of the safety of the plastic deformation, in the case of the tubes drawing without inside guard, when the tool is placed in the maximum of the ultrasonic waves oscillation and it is activated along the drawing direction,ultrasonic vibration drawing / UVD system". It is explained by the "friction reversal" during T/2-2t(1), for one oscillation time (T), when v(dr)/v(v)< 1, (v(dr) is the rate of drawing and v(v) is the vibratory rate of the die). So, it is recommended the application of the ultrasonic energy in the drawing of the tubes made of metallic materials which are hard malleable by cold plastic deformation.