中文摘要：

提出一种大尺寸圆柱形超声塑焊开槽焊头的设计方法，并用有限元软件对其正确性进行验证。该方法通过将圆柱形开槽焊头和大尺寸圆柱形半波振子作比较，利用等效机械阻抗的概念求出焊头的频率方程，其间利用表观弹性法计及横向振动对焊头的影响。此外利用该方程研究开槽数、槽宽度以及槽长度等因素对焊头振动特性的影响。按此方法设计几组大尺寸圆柱形开槽焊头，并用有限元软件对其进行模态分析，结果表明焊头谐振频率的仿真值和理论值符合地很好。

英文摘要：

A design method for large cross-section ultrasonic plastic welding cyhndrical-type horns with slots was presented and finite element software Ansys was used to validate this method. Firstly, the cylindrical-type horn with slots was compared with a large cross-section cylindrical-type half wavelength resonator, and their resonant frequencies were assumed to be the same. Then based on the idea that their mechanical impedances should be equivalent, the frequency equation of large cross-section cylindrical-type horn with slots was derived. Meanwhile, the influence of transverse vibrations on horn was considered by apparent elasticity method. Finally, the relations between the number, wide or length of slots and the vibrational characteristics of horn were studied by this frequency equation. Three large cross-section ultrasonic plastic welding cylindrical-type horns were designed by this method and their resonant frequencies were calculated using Ansys. Results show that the calculated resonant frequencies agree well with the original designed frequencies.