| Summary: | The welding of foils, textiles, and textile composites made of thermoplastic polymer materials using machines with an ultrasonic rotary sonotrode is a high-tech welding technique. Many authors have dealt with only a few parameters in earlier papers, mainly mentioning the speed, i.e., the welding time, and the power of the ultrasonic generator. In this paper, the acoustic model of ultrasonic welding is defined. Based on the model, a group of 44 different parameters important for ultrasonic welding of polymer materials has been summarised, namely 12 parameters of the polymer material, 11 general acoustic and electroacoustic parameters, and 21 technical parameters depending on the ultrasonic machine. Based on this, a comprehensive mathematical derivation was carried out, linking parameter groups with other findings from acoustics, thermodynamics of polymers, and technical and technological parameters of welding polymer materials. The most important parameters are the power of the ultrasonic generator and the welding time, which in practice are adjusted to produce a solid weld. The method of measuring the amplitude of the sonotrode using a photonic sensor is presented in this paper. For 42 groups of welds done at various welding speeds and ultrasonic generator powers, the breaking forces of ultrasonic welds were measured. There are illustrations of power dependence and breaking forces. The accuracy of the mathematical model was confirmed by comparison with the calculation results based on the findings of these measurements.
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