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且环保的连接方法，可在几分之一秒内将相似或不同的材料制成坚固的接头。在该过程中使用的焊接工具（称为超声波焊极）通过与上接合伙伴接触的振荡而导致结合的形成，并且因此暴露于高的热应力和机械应力，这在连续使用中导致仅几天的相对短的寿命。最近，申请人开发了特别用于钛合金的超声焊接的超声波焊极，其磨损行为不仅取决于超声波焊极材料，而且显著地取决于超声波焊极的结构。在本研究项目中，将系统地研究超声焊极结构对Ti/Al接头质量和超声焊极寿命的影响。有限元模拟用于在第一步骤中计算具有不同结构的尖端和连接伙伴的超声波焊极的应力和变形，而不必制造超声波焊极。为了验证计算结果，将制造具有最有前途的结构的超声波焊极，并考虑可实现的强度和连接区域中产生的微观结构进行焊接实验。平行的焊接实验，超声焊极磨损的记录和特点。结合所得的接头强度和磨损行为的连接区域的微观结构的分析将支持优化的超声波焊极结构的设计，以增加接头强度，延长工具寿命，并扩大超声波焊接超声波焊极的基本理解。

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.