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Slovak University of Technology Faculty of Material Science and Technology in Trnava. Machine T ools A nd D evices F or S pecial T echnologies. Ultrasound machining. Machining by ultrasound. ultrasound – acoustic oscillation with frequency higher than 20 kHz.
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Slovak University of Technology Faculty of Material Science and Technology in Trnava Machine Tools And Devices For Special Technologies Ultrasound machining
Machining by ultrasound • ultrasound – acoustic oscillation with frequency higher than 20 kHz. • sonar – first using of ultrasonic in the beginning of 20th century • Ultrasonic machining – process that used ultrasonic (mechanical acoustic oscillation) for material removing with destroy surface by influence of oscillation abrasive. First patent for ultrasonic machining is from half 20th century.
Processing by ultrasound Machining of strong and brittle material: • ceramics, • jewel and semi jewel, • graphite, • glass, • Semi finished materials, • Hardened and thermal resistant materials,
Principle of ultrasonic machining Mechanical grinding influence of suspenzion (substance of liquid and solid material) consisted of abrasive mixtured in the liquid (water, oil, petroleum, alcohol, ...). Suspenzion is directed between tool and workpiece. Tool is vibrated to frequency 20 kHz to 30 kHz. Vibration of tool facing place are directed to abrasive grains that impacted to machining surface and removed the material.
Material removing Material removing is possible by: • Mechanical influence – elements of the abrasive removed material in the straight impact – abrasive influence, • microginding - after impact of freely moving abrasive particulate, • Cavitations effect of abrasive suspension, • Property and chemical action of liquid media in suspension.
Kinematics of ultrasound • Main movement – longitudinal tool vibrations • shift: • longitudinal, • Lateral, • circular. By movement combination and tool profile shape (longitudinal and lateral) maybe realize different operations of machining.
Specific field of application this methods: • Material cutting, • Groove and holes (circular or unsymmetrical shapes too) deepening, • Deep holes boring – for barrel systems, • Milling and threading, • Polishing, ceramics grinding and lapping, • Machining of complex electrode on spark erosion, • Forming tool manufacturing from sintering carbide, • Rubber and thermoplastic cutting – clean cut without bur, • Composite material cutting and boring, • Diamond and gemstone shaping by using diamond dust or cubic nitride boron into abrasive suspension
Ultrasound using in machining • Ultrasound machining – ultrasound processing the operation of machining, amplitudes abrasive that removed material, • Machining aided by ultrasound – conventional kinds of machining (f.e. turning) – tool that realised machining is vibrated by ultrasound and with respect of this are decreased cutting forces, increased roughness and accuracy of the machined surface...
Turning aided by ultrasound • Turning of the strong and brittle materials, • cutting forces reduction, turning qualities and accuracy improvements is observed at tool vibration direction excitation parallel via the main cutting motion (tangential vibration), • small amplitude (3 till 4 µm) increase tool durability 3 till 7-times • Vibrations with big amplitude decrease the tool durability,
Drilling aided by ultrasound • Drilling of bore copper, aluminium alloy and anticorrosive steel workpieces by lanced drill, • Chip crumbling is easier, • Higher productivity, • amplitude in interval 6 till 8 µm, • overall torque is reduced about 50 till 65%, • drill tools durability increase 2 till 3-times, • Higher dimension accuracy
Ultrasound drilling • Tool vibrated the abrasive in the suspension, • Material is removed by the same mechanism as in the grinding, • Used for the strong and brittle materials, • High accuracy and production,
Thread cutting aided by ultrasound • Lower friction, seizing is removed and decreased is cutting force and overall torque, • Ultrasound vibrations influenced in tool axis direction, amplitude is several µm, • For thread cutting is not need the set of taps, • Is possible to use the slot less screw-tap, • High quality of thread surface.
Smoothing by diamond and surface strengtheningaided by ultrasound • Plastic deformation of surface layer, • Small forces (approximately 200 – 300 N), • Ultrasound vibrations intensificated process of smoothing and strengthening, • Increased micro strenghtness of surface approximately 1,5 times, • Suitable positioning of the pressure intensity in the surface layer, • Lower roughness of the surface, • High abradibility of the strengthnesses surface, • Higher lifetime of die tubes,
Smoothing by diamond and surface strengtheningaided by ultrasound
Ultrasound grinding • Higher quality of the machined surface • Higher tool lifetime, • Self – focusing of tool, • Tool cleaning, • Using in the grinding circular and in the flat,
Machines for machining by ultrasound • magnetic transducer, • concentrator, • tool, • Ram, • against-weight, • Leading surfaces, • workpiece, • Pumping device, • tank, • weight.
