Research On Focused Ultrasonic Machining Technology

High intensity focused ultrasound is currently widely used in the medical field.This paper aims to explore the application of high intensity focused ultrasound to the machining field.A focused ultrasonic machining is proposed in which material removal is achieved by the ultrasonic energy at the focus.The process parameter optimization and material removal mechanism of focused ultrasonic machining were further studied.The focused ultrasonic field was simulated by COMSOL Multiphysics.The simulation results show that the focused ultrasonic field can form tiny areas with high sound intensity on the surface of the workpiece,which is the basis for the application of focused ultrasonic to machining.An acoustic radiation force measuring platform was established by the radiation force balance method.The sound power of the focused ultrasound transducer was converted by the measurement results.The maximum output sound power is about 100W.The sound power calibration is theoretical basis and data support of focused ultrasonic machining experiments.A focused ultrasonic machining experimental platform was built by a focused ultrasonic generation system,a positioning system,and a cooling system.Four kinds of materials with different hardness were selected as the workpiece of the feasibility experiment.The experimental results show that the focused ultrasonic cannot remove material from high hard materials.The surface of soft materials is mostly plastic deformation with less material removal.Significant material removal areas appeared on the surface of the single crystal germanium under the action of focused ultrasonic.Single crystal germanium was used as the workpiece material.Si O₂ polishing liquid,clean water,deionized water and ethanol were used as the medium in focused ultrasonic machining.The parameters and material removal mechanism were analyzed.The experimental results show that the focused ultrasonic trajectory machining has higher efficiency and quality.The cavitation bubble in the medium with large surface tension can release more energy to lead to higher efficiency but lower quality.Cavitation bubbles are more evenly distributed in the liquid medium with solid particles,resulting in a higher quality machined surface.The material removal is mainly caused by cavitation bubbles collapsing on workpiece.cavitation bubbles directly impact the surface of the workpiece,and cause brittle fracture of the material.Ultrasonic cavitation can generate H,OH,HO₂ radicals in water,which promote the materials removal.