Demonstration of an energy-optimized process control for metal ultrasonic welding based on process characteristic values

• Applicant: Professor Dr.-Ing. Uwe Reisgen
• Subject Area: Joining and Separation Technology
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 470052705

In the transfer project "Demonstration of an energy-optimized process control for metal ultrasonic welding based on process characteristic values", ISF is developing the prototype of a model-based process control together with the application partner Schunk Sonosystems GmbH. Schunk Sonosystems GmbH is recognized worldwide as a specialist in the field of ultrasonic metal welding.Ultrasonic metal welding is particularly suitable for joining electro technical components and is increasingly coming into industrial focus due to the growing complexity of electronic systems. Despite its industrial spread, process fluctuations can occur in ultrasonic metal welding. These fluctuations often cannot be explained, since there is a lack of scientifically sound knowledge about the complex interactions between tools and parts to be joined during the welding process and, as a result, they are hardly taken into account in the mostly empirical research. On the basis of our own investigations within the framework of the DFG predecessor project "Process analysis of ultrasonic metal welding by acoustic emission", it has already been shown that information on the thermomechanical processes taking place within the joining zone can be obtained from the externally measurable vibration behaviour of the overall mechanical system, consisting of welding tools and joining parts. The vibration behaviour of the overall system correlates with the joint formation.In this transfer project, this information will be quantified, transferred to a statistical model and used for process control. By optimizing the energy input for each joint part, it is possible to achieve higher strengths for the individual joint and lower quality scatter overall. To achieve this, the optimum process end is determined in the ongoing welding process as a function of the actual joint formation and adjusted accordingly. Suitable sensors and high-frequency data acquisition are used to record the structure-borne sound signals and other signal sources, such as the penetration distance and the power consumption of the system. In combination with the quality data of the welds, correlating sensor signals are identified in the data sets using suitable statistical methods and process parameters are quantified. Subsequently, the processing of the high-frequency signals is realized in real time in a prototype system for process monitoring, i.e. the data is analysed in the ongoing welding process and converted into the process characteristic values. When the optimum end of the process is identified on the basis of the process characteristic values, this information is transmitted to the welding system and the process is terminated at the appropriate time.

• DFG Programme: Research Grants (Transfer Project)
• Application Partner: Schunk Sonosystems GmbH