Study Of Ultrasonic Cutting Hard And Brittle Materials By Using Sandwich Bending Vibration Transducer

Sandwich transducer bending vibration ultrasonic cutting is an effective method ofprecision processing for the hard and brittle materials. Compared with the traditional ultrasonicvibration cutting which is driven by the longitudinal vibration transducer, sandwich transducerbending vibration ultrasonic cutting is revolutionized in clamping efficiency and acousticcoupling efficiency and universality of the size of the materials. Apply the sandwich bendingvibration transducer in engineering is limited by the theoretical derivation which is morecomplex than longitudinal vibration. At present, international and domestic academics havealready provided some design theory of bending vibration sandwich transducer which can meetthe engineering application, but actually apply the sandwich bending vibration transducer for testand product is almost blank.Perfect the design theory of sandwich bending vibration transducer, analysis the machiningmechanism of bending vibration cutting hard and brittle materials and carries on experimentalanalysis. The aims are providing guidance on sandwich transducer bending vibration ultrasoniccutting hard and brittle materials. The main content and achievement of the dissertation are asfollowing:1. Based on approximate design theory of bending vibration sandwich Piezoelectric ceramictransducer, the size and assembly parameters of sandwich bending vibration transducer aredesigned by preliminary modal analysis of UG NX NASTRAN and modal analysis whichconsider preload force of ABAQUS and combined with test result of impedance analysis.2. Provide a conception of critical position which the direction of work movement and thedirection of tool vibration are collinear. Deduce the movement of nose of tool and the change ofactual cutting angle of tool in different position. Regard as critical position is the best positionfor cutting hard and brittle materials and provide theory basis for later test.3. Completed assemblies of sandwich bending vibration transducer and tested on characterof vibration, install the system of bending vibration on NC lathe by special fixture, completedbuilding the platform of test.4. Ultrasonic vibration cutting in the tiny cutting depth can be as much times blunt shapedhead oblique impact contact process, analysis distribution of stress in Elastic region andinfluencing factors in this process. Because the character of separation of ultrasonic vibrationcutting in the tiny cutting depth, regard that longitudinal crack controlled by tensile stress produce in the Head back edge. Avoid longitudinal crack controlled by tensile stress is base onfracture criterion of brittle material.5. The reasonable cutting parameters and lubrication condition by experiment can avoid thelongitudinal crack controlled by tensile stress, improve the surface quality and machiningprecision.