Abstract: Micro-milling is the main method to realize precise machining of aviation micro parts. However, affected by the size effect, when using this method to process titanium alloy and other high plasticity and high strength materials, it is easy to produce serious cutting deformation, burrs and other defects, affecting the machining quality of micro parts. To solve the problems of large plastic deformation and severe burr damage in the machining process of titanium alloy micro-groove, an ultrasonic spiral assisted milling and grinding method is proposed. The plane machining path is transformed into three-dimensional spiral, so that the end surface and cylinder surface of the micro-milling and grinding tool are periodically separated from the workpiece, which can reduce the micro-milling and grinding force and improve the micro-groove machining quality. The simulation and experiment of ultrasonic assisted titanium alloy micro-groove machining are carried out. The effects of different ultrasonic vibration modes on the burr size, surface quality, fractal dimension and micro-milling & grinding force of micro-groove are compared. The results showed that, compared with non-ultrasonic assisted, longitudinal torsion ultrasonic assisted and tangential ultrasonic assisted machining methods, ultrasonic spiral assisted machining obtained the smallest burr size, the lowest surface roughness, the largest fractal dimension and the smallest force. The machining quality of titanium alloy microgroove is improved. The experimental result verifies the advantage of ultrasonic spiral assisted machining method in titanium alloy micro-groove machining.

Key words: ultrasonic vibration, micro-milling, micro-grinding, polycrystalline diamond tool, titanium alloy