| In the ultrasonic elliptical vibration cutting(UEVC),the ellipse trajectory of the tool tip is considered to be one of the important factors affecting chip and surface roughness,which determines the quality of the machined surface.However,the research on the ellipse trajectory control and cutting mechanism of the tool tip is not mature at this stage.Although many scholars at home and abroad have successively designed UEVC devices to study the influence of tool tip elliptical trajectories on cutting caused by excitation frequency and amplitude,these UEVC devices mostly use rigid connections,resulting in low two-way coupling efficiency.At the same time,the orthogonal design is seldom used in the device,it is difficult to control the ellipse trajectory of the tool tip and the excitation frequency is mainly concentrated below 60 KHz.In summary,the development of a set of orthogonal and flexible output UEVC device with excitation frequencies above 60 KHz to achieve large amplitude and easy-to-control ellipse trajectory of the tool tip,and cutting experiments for the change of the ellipse trajectory of the tool tip are currently studied focus.The main research contents of this article are as follows:(1)Research on the pure orthogonal UEVC device based on the guided wave band transmission technology.Based on the dynamic principle,the dynamic response model of the flexible guided wave band is established,and the coupling mechanism of the orthogonal signal transmission of the transverse and longitudinal wave guides is analyzed.At the same time,the frequency impedance characteristics of a guided wave band group consisting of multiple small cross sections and the single guided wave band with the same cross section are discussed in depth.Research shows that orthogonal flexible guided wave bands can achieve independent transmission of signals and have strong load decoupling capabilities.Compared with the singleguided wave band with the same cross-section,the use of multiple-guided wave band groups has the advantages of reducing system impedance and increasing transmission power.Through this theoretical research and finite element optimization design,the development of a two-dimensional pure orthogonal guided wave band UEVC device with excitation frequency of 96.8KHz is achieved.(2)The tool tip elliptical trajectory control and cutting mechanism of pure orthogonal guided wave UEVC device were studied.By analyzing the basic parameter of the tool tip elliptical trajectory change-amplitude and phase difference,the model of the tool tip elliptical trajectory deflection control is established and the research of finite element cutting mechanism is completed based on the model.Cutting simulation results show that when the amplitude and phase difference are adjusted at the same time,the cutting force is smaller when the deflection angle is 20° and 70°;Only the phase difference is changed,the cutting force is small when the phase difference is 60°-75°.In addition,compared with conventional cutting(CC)finite element analysis,UEVC has verified excellent cutting characteristics such as reduced cutting force and chip thickness.(3)The performance of the two-dimensional pure orthogonal guided wave UEVC device and the tool tip elliptical trajectory deflection test.The test results show that the resonance frequencies of the transducers in the two directions differ by only 0.03%,achieving the same frequency excitation,and obtaining an amplitude output of 0.54?m.In addition,the measured tool tip elliptical trajectory of the variable phase difference is highly consistent with the theoretical model.(4)Build a precision machining platform to complete cutting test research and verification.Cutting experiments with a variable phase difference tool tip elliptical trajectory show that the cutting effect with a phase difference of 60° is best.With the help of ultra-precision machine tool combined with high-frequency UEVC technology to process the micro-prism microstructures.Through the above research,we have completed the control of the change of the tool tip elliptical vibration trajectory and the mechanism of the impact on the surface quality of ultra-precision machining.Obtain the best cutting process parameters and realize the basic burr-free processing of micro-prism microstructures.The research results of this paper have theoretical significance and engineering application value for the design of UEVC system and ultra-precision machining. |
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