Stiffness enhancement analysis of ultrasonic-assisted milling titanium alloy curved thin-walled parts

Machining of titanium alloy curved thin-walled parts, one of the challenges in aerospace engineering, has attracted much attention. In this article, longitudinal-torsional composite ultrasonic-assisted milling (LTCUVM) was applied to the thin-walled parts, and the stiffness characteristics were studied. Firstly, the cutting edge trajectory of LTCUVM was discussed. Then, the dynamic equation of the thin-walled parts was established, and the stiffness characteristics were theoretically analyzed. Finally, the influences of curvature and machining parameters on the stiffness of the thin-walled parts were studied through experiments. The experimental results showed that the stiffness in LTCUVM was evidently higher than that in CM. With the increase of curvature, the stiffness enhancement multiples of LTCUVM increased first and then decreased. In addition, larger ultrasonic amplitude, smaller feed rate, radial cutting depth, and spindle speed could achieve better stiffness enhancement effect, and the advantages of LTCUVM could be brought into full play. The findings of this research provide an important reference for machining titanium alloy curved thin-walled parts.