The next step towards virtual machine tools: Simulation of damping effects caused by the machine-process interaction
Metal-Cutting and Abrasive Manufacturing Engineering
Final Report Abstract
This research project was concerned with improving the accuracy of dynamic models of machine tools. The objective was to develop a model to predict dynamic instabilities that can occur due to the interaction between the machine tool structure and the machining processes. These accelerate tool wear, can lead to poorer machining results, and can even damage the machine tool itself. So, a comprehensive predictive model that encompasses all aspects of the machine operation was developed. For this, methods for identifying the structural dynamics effects during machining were investigated. Conventional experimental modal analysis techniques for exciting the machine tool were found to be unsuitable for active machining due to safety concerns. Alternative approaches were therefore investigated, including specially designed machining processes, excitation of the structure via the built-in feed drives, and the use of advanced tools equipped with piezo actuators. The use of an inertial actuator near the tool center point (TCP) proved to be the most suitable method among the tested approaches. This technique enabled a wide range of controlled excitations, and thus the reproducible determination of frequency responses during the process. The experimental investigations carried out using this measurement method provided insights into the influence of various process-induced factors on the damping properties and the dynamic behavior of machine tools. The factors included the position of the TCP within the workspace, the feed rate, the spindle speed, and the machining forces acting on the milling spindle. The research results emphasize the need for simulations that take these factors into account to make highly accurate stability predictions. The disaggregation of the damping effects during the machining process represents a significant advance in understanding the dynamics of machine tools. Although the full integration of all the process-induced damping effects into the simulation model is pending, this accomplishment lays a strong foundation for future works to fully exploit these experimental results and achieve complete integration.
Publications
-
Der digitale Zwilling der Werkzeugmaschine/The digital twin of machine tools. wt Werkstattstechnik online, 111(03), 179-183.
Fischer, Andreas; Semm, Thomas; Zäh, Michael F.; Spescha, Daniel & Ceresa, Nino
-
Identification of optimization potentials using flexible multibody models with local damping information. Procedia CIRP, 99, 75-79.
Semm, Thomas; Fischer, Andreas & Zaeh, Michael F.
