纵扭超声振动加工在碳纤维复合材料等硬脆性材料上的应用越来越得到重视，针对现有纵扭超声换能器存在扭振分量较小或纵扭节面不重合等问题，设计一种新型的纵扭超声换能器。通过理论解析法设计了一种指数型变截面杆纵振超声换能器，然后在指数型变截面杆上设计螺旋槽，将一部分纵向振动转换为扭转振动；利用有限元软件分析螺旋槽结构参数对纵、扭谐振效果的影响规律，优选出最佳的螺旋槽参数；在此基础上对换能器进行模态分析和瞬态分析，结果表明换能器能够实现纵扭超声振动，且谐振频率与设计值误差较小，振幅值满足一般加工要求；最后对设计好的换能器实物进行阻抗分析和振幅测试，结果表明谐振频率与仿真值相差较小，纵振振幅9.4 μm，扭振振幅5.3 μm，能够适用于大部分的超声加工，也验证了设计方法的正确性。
The application of longitudinal torsional ultrasonic vibration machining in carbon fiber composite material and other hard brittle materials on more attention. Aiming at the problem that the torsional vibration amplitude is small and the coupling of longitudinal and torsional vibration is poor of the longitudinal-torsional ultrasonic transducers, a new longitudinal-torsional ultrasonic transducer is designed. An exponential type longitudinal vibration ultrasonic transducer with variable cross section is designed by theoretical analysis, then designed helical grooves in the exponential section to make a portion of longitudinal vibration convert to torsional vibration. The influence of structural parameters of helical groove on longitudinal and torsional resonance is analyzed by FEM, so the optimum helical groove parameters are optimized. The modal analysis and transient analysis of the transducer are carried out, the results show that the transducer can realize longitudinal vibration and torsional vibration, and the deviation was small for the resonance frequency between design value with simulation value, and the simulation amplitude value meets the general processing requirements. Finally, impedance analysis and amplitude test of the designed transducer are carried out, the results show that the resonance frequency is smaller than the simulation value, the longitudinal vibration amplitude is 9.4 μm, and the torsional vibration amplitude is 5.3 μm, which can be applied to most ultrasonic machining, and the correctness of the design method is also verified.
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