Development of durable sonotrode concepts for ultrasonic welding of Ti alloys by designing an efficient structuring of the sonotrode tip

超声波焊接工艺是一种廉价和环保的连接方法，可以在几分之一秒的时间内实现类似或不同材料的坚固连接。在这一过程中使用的焊接工具称为声电极，通过与上连接伙伴接触时的振荡形成粘结，因此暴露在高热应力和机械应力下，连续使用时寿命相对较短，仅为几天。近年来，针对钛合金的超声焊接而研制的超声波焊条，其磨损性能不仅与超声波焊条的材料有关，而且与超声波焊条的组织结构密切相关。在本研究项目中，将系统地研究声道结构对钛/铝接头质量和声道寿命的影响。有限元模拟被用来计算具有不同结构的尖端和第一步中的连接伙伴的声棒的应力和变形，而不必制造声棒。为了验证计算的有效性，将制造具有最有前景的结构的声电极，并将进行焊接实验，以考虑可获得的强度和由此产生的接合区的微观结构。与焊接实验平行，记录和表征了超声波电极的磨损。结合所得到的接头强度和磨损行为对接头区域的微观结构进行分析，将支持优化的超声波电极结构的设计，以提高接头强度，延长工具寿命，并拓宽对超声波焊接超声波电极的基本理解。

Ultrasonic welding processes are inexpensive and environmentally friendly joining methods to cre-ate robust joints of similar or dissimilar materials within fractions of a second. The welding tools used in this process, known as sonotrodes, cause the formation of the bond by oscillation in contact with the upper joining partner and are therefore exposed to high thermal and mechanical stresses, which in continuous use result in a relatively short longevity of only a few days. Recently, sono-trodes where developed especially for ultrasonic welding of titanium alloys by the applicants, whose wear behavior depends not only on the sonotrode material but also significantly on the structuring of the sonotrodes. In this research project, the influence of the sonotrode structuring on the quality of Ti/Al joints and the longevity of the sonotrodes will be systematically investigated. Finite element simulations are used to calculate stresses and deformations of sonotrodes with differently structured tips and the joining partners in a first step, without having to manufacture the sonotrodes. In order to validate the calculations, sonotrodes with the most promising structuring will be manufactured and welding experiments will be performed considering the achievable strengths and the resulting microstruc-ture in the joining area. Parallel to the welding experiments, the sonotrode wear is documented and characterised. The analysis of the microstructure in the joining area in combination with the resulting joint strengths and the wear behaviour will support the design of optimised sonotrode structures to increase joint strengths, extend tool life and broaden the basic understanding of ultrasonic welding sonotrodes.