Mechanism of a high performance and energy efficiency parallel ultrasonic vibration-assisted cutting

Shafts made from titanium have been widely used in aerospace, medical and automobile manufacturing field fields. Due to their low thermal conductivity, low stiffness and high energy consumption, they are easy to deform during cutting, resulting in low machining performance, production and energy efficiency. A new high performance and energy efficiency process, Parallel Ultrasonic Vibration-assisted Cutting (PUVC), is proposed in this work to overcome above challenges. This paper introduces two important cutting modes of PUVC shared cutting surfaces (SCS) and non-shared cutting surfaces (NSC), where the NSC mode improves the cutting efficiency and decreases the energy consumption. Through analysis of PUVC's main cutting force, cutting temperature and workpiece stress field, the cutting mechanism of PUVC is studied. Furthermore, an experimental validation is conducted with respect to the cutting temperature and surface residual stresses, showing strong correlations with modelled predictions. Besides, the PUVC and Single-tool Ultrasonic Vibration-assisted Cutting (SUVC) are compared and analyzed with different length-diameter ratios to asses the advantages of PUVC for slender shafts. Experiments and simulations have shown that the SCS model has better fit than the NCS model. PUVC has significant advantages over workpieces with large aspect ratios. When the aspect ratio is 5, the temperature can be reduced by up to 30 %, and the diameter error can be as low as 0.036 mm. Compared with SUVC, PUVC has lower power consumption (11 %–18 %), but dual tool machining increases residual stress.