Development of a Compact Longitudinal-Bending Composite Ultrasonic-Assisted Turning Tool for Micro-Lathe Machining

With the growing demand for surface quality in micro-precision machining, twodimensional ultrasonic-assisted turning (UAT) has attracted considerable attention owing to its ability to improve cutting performance and surface integrity. However, conventional two-dimensional UAT tools have generally employed sandwich-type piezoelectric transducers, resulting in limited vibration controllability, increased structural complexity, and poor adaptability to the restricted installation space of microlathes. To address these limitations, a compact longitudinal-bending composite ultrasonic-assisted turning (LB-UAT) tool based on bonded piezoelectric patches is proposed. The proposed tool adopts a single-transducer and dual-patch independently excited configuration, enabling integrated excitation and independent regulation of longitudinal and bending vibration modes. Compared with conventional twodimensional UAT tools, the transducer volume is reduced by approximately 88.15% while maintaining controllable two-dimensional vibration output. A dynamic model and a force-structure coupled finite element model are established to optimize structural parameters and achieve modal matching. Experimental results demonstrate that the proposed tool significantly improves micro-groove quality and turning surface integrity. Surface roughness decreases by approximately 62.59%, while built-up edge formation and burr generation are effectively suppressed. In addition, shorter chips and uniformly distributed continuous micro-textures are obtained. The proposed tool provides a compact and effective solution for high-quality micro-turning of difficult-to-machine materials and offers a promising approach for integrating two-dimensional ultrasonic vibration technology into miniature machine tools.