Experimental Study on Fine Titanium Wire Drawing with Two Ultrasonically Oscillating Dies

This paper investigates the influences of ultrasonic vibration on the two-pass titanium wire drawing process through experiments conducted at different drawing speeds (99-480 mm/s) and under various ultrasonic amplitudes (5.63- $13.97~\mu \text{m}$ ). Ultrasonic vibrators were designed, analyzed, and manufactured to impose ultrasonic vibrations, along opposite directions, on the dies. Their dynamic characteristics were predicted by finite element analysis and subsequently measured using specific instruments. The interaction between the two vibrators, when driven by the same ultrasonic generator, resulted in the deviation of coupled resonant frequency (50-60 Hz) and the decrease in maximum output amplitudes (about 4 $\mu \text{m}$ ). A wire drawing equipment was developed to record the drawing forces under different experimental conditions, and the surface morphologies of the drawn wires were then inspected with a scanning electron microscope. Results show that increased ultrasonic amplitude contributes to greater drawing force reduction, whereas higher drawing speed brings about the reverse effect. At the lowest drawing speed and with the largest ultrasonic amplitude, the drawing force declined by over 50%. Both factors have influences on the surface finish of the drawn wires. However, higher drawing velocity (480 mm/s) with the moderate ultrasonic amplitude ( $9.69~\mu \text{m}$ ) turned out to be most effective in removing the surface defects of the wire products. This paper provides a low-cost, high-efficiency, and eco-friendly approach for the industrial production of fine titanium wires at room temperature.