Monitoring of the ultrasonic welding process

Abstract

Ultrasonic welding is a widely used joining method for joining individual components. Special features are local heating of the joining partners, short welding times as well as a high economic efficiency of the process. The weld seam quality depends on numerous factors. The welding process is affected intentionally and unintentionally, starting from the process parameters, the tolerances of the welding parts up to theories about a chaotic material behavior. This can lead to varying process qualities. Up to now, the weld seam quality is evaluated only by means of a destructive inspection of the weld seam. The monitoring of the ultrasonic welding process provides information about the weld seam quality within the welding process. Within the scope of this work, the monitoring of the mechanical vibrations occurring in the anvil as well as the temperature development in the joining zone of the weld seam are shown. From characteristic values of the monitoring process, a comparison is made between the weld seam qualities and subsequent tensile tests. The results show a significant correlation between the measured tensile strengths and the energy densities acquired at the piezo oscillator.