Optimization Design Of Longitudinal-torsion Resonance Ultrasonic Milling System And Research On Machining Of SiCp/Al Composite

SiCp/Al composites are widely used in defense industries such as aerospace and aviation,as well as high-tech fields such as aircraft,automobile manufacturing,semiconductor industry and optical precision instrument industry due to their excellent material properties such as high strength and wear resistance.Although the high-hardness Si C particles improve the wear resistance and strength of the SiCp/Al composite,it also makes the overall aluminum matrix material less ductile,increasing the plastic deformation during processing and the residual stress on the workpiece surface after processing,allowing It is extremely difficult to use common processing methods to achieve efficient and precise ultra-precision processing.Longitudinal torsional resonance ultrasonic milling process,the tool is completely separated and intermittent machining state,high frequency longitudinal torsional vibration makes the milling force and torque of the tool are greatly reduced,the rigidity and stability of the system are also improved,and the tool adhesion is reduced Wear and abrasive wear have improved the surface quality of the workpiece.In this thesis,a half-wavelength longitudinal torsional resonance ultrasonic transducer is designed to produce longitudinal torsional resonance under the unidirectional vibration excitation.According to the equivalent circuit method,the structural design of the conical stepped composite horn is carried out.Through the finite element analysis of the ultrasonic transducer,the modal shape and resonance displacement are obtained,which verifies the rationality of the design.Using the orthogonal experiment method,the influence of the size and number of chute grooves on the vibration characteristics of the ultrasonic transducer was studied.Finally,the designed longitudinal torsional resonance ultrasonic transducer was optimized by the comprehensive balance method so that the longitudinal direction The amplitude is increased by 56.88%,the torsional amplitude is increased by 136.46%,and the resonance frequency error is reduced by 79.41%.In order to further study the mechanism of ultrasonic milling,the dynamic model of the kinematic model of longitudinal torsional resonance ultrasonic milling was established.The trajectory of ultrasonic milling and ordinary milling blades was obtained.The milling force of the system was predicted.The influencing factors of material removal are analyzed.In order to investigate the variation of the surface quality of SiCp/Al composites under longitudinaltorsional resonance ultrasonic milling,an experimental platform for longitudinal torsional resonance milling was built,a single factor experiment was designed,and the processed SiCp/Al was observed by laser scanning confocal microscope The surface morphology of the composite material has been concluded that when the spindle speed is 3000r/min and the milling speed is 180m/min,the surface roughness value is the smallest,and the surface quality decreases with the deepening of the milling depth.This thesis provides directions and ideas for the optimal design of longitudinal torsional resonance ultrasonic transducers,theoretically analyzes the mechanism of ultrasonic milling,provides reasonable process parameters for ultrasonic milling of SiCp/Al composite materials,and promotes longitudinal torsional resonance ultrasonic milling The promotion and application of processing has important strategic significance and social and economic benefits.