Abstract: As a typical difficult-to-machine material which is widely used in aerospace and aviation field, the high quality and efficient machining of titanium alloys has always been the hotspot in mechanical machining. Focused on the force and heat concentrations in the machining of titanium alloys, with assistant of high-pressure cooling, an ultrasonic vibration cutting method in which the separation direction is vertical to the cutting direction is applied to the high quality and efficient machining. At first, the tool and workpiece periodical separation condition is deduced by mathematics. Then, based on this, the turning experiments on titanium alloys are conducted. Through setting different cutting parameters (cutting speed, feedrate and depth of cut) and cooling parameters (cooling pressure), the relationship between these parameters with cutting force, cutting temperature, tool wear progress, workpiece surface quality and tool life are investigated. The experimental results demonstrate that ultrasonic vibration cutting with assistant of high-pressure cooling fluid can reduce the cutting and cutting temperature, decelerate the tool wear, improve the surface quality and enhance the tool life. Under the condition of 20 MPa cooling pressure, the cutting speed of titanium alloys can increase to 400 m/min with workpiece surface roughness Ra no larger than 0.4 μm. In this regard, the long tool life and precision machining of high quality and efficiency are realized.

Key words: titanium alloys, ultrasonic vibration cutting, high-pressure cooling, tool life, surface quality