Development of a high-precision piezoelectric ultrasonic milling tool using longitudinal-bending hybrid transducer

A novel piezoelectric ultrasonic milling tool based on a longitudinal-bending hybrid piezoelectric transducer (LBHT) is proposed. The major novelty of the proposed tool is that through longitudinal vibration and bending vibration of the tool the impact ironing effect (IIE) and intermittent cutting effect (ICE) simultaneously, thus achieving high-precision milling. Above all, the structure and operation principle of the longitudinal-bending hybrid vibration-assisted milling (LBHVAM) system is amply depicted. Then, simulations and analyses are carried out to design and analyze the structure size and critical ICE conditions. Ultimately, a prototype is manufactured and the vibration tests and machining experiments have been carried out. The results indicate that the cutting force of LBHVAM of titanium alloy is 39.3% and 27.2% lower than the conventional milling (CM) and longitudinal vibration-assisted milling (LVAM), and the propensity of burr formation is significantly reduced. Furthermore, the surface roughness under LBHVAM reaches Sa 0.102 μm, which is 85.2% and 54.5% lower than CM and LVAM. Above results demonstrate that the proposed LBHVAM tool not only has unique advantages in reducing cutting force and burr formation but also possesses great potential in improving machining accuracy, which is highly desired in ultra-precision machining of difficult to cut materials.