Semi-active component for chatter suppression of metal cutting machine tools

• Applicant: Professor Dr.-Ing. Jürgen Fleischer
• Subject Area: Production Automation and Assembly Technology
• Term: from 2017 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 329109043

The machining accuracy and the productivity improvement of a chip-removal machine tools are limited by the interaction between the workpiece and the tool. This interaction represents the reciprocal effect between the cutting process and the compliance behavior of the machine tool. At high cutting forces and insufficient machine stiffness or damping in the machine, self-induced vibrations (chatter) can occur. These vibrations endanger the stability of the machining process.To reduce chatter, many approaches deal with the enhancement of the compliance behavior of the machine. Complex active systems are state of research, but their implementation hardly ever takes place in an industrial environment due to the high costs. Instead, mainly simple passive systems are to be found in the industrial environment. Nevertheless, these systems are only suitable and conceivable for certain equipment and processes.At wbk, Institute for Production Science, research is being conducted on a new approach where the natural frequencies of machine tools can be changed using a semi-active component. Previous achievements show that the compliance behavior of this new component can be changed in any frequency ranges. The semi-active approach to reducing chatter vibrations combines the advantages of active and passive systems, since it is valid across all frequencies, and promises a high implementation potential.The aim of this work is to tap the full potential of this approach, in order to suppress chatter. It shall be investigated how the processing stability of a machine tool can be improved through a targeted adaptive change of the dynamic behavior. For this purpose, the modeling of the adaptive component is first examined in order to understand the effects and interactions of the liquid used on the compliance behavior. Subsequently, an automated procedure is developed to optimize the structure of the semi-active component in order to increase the processing stability. Finally, the approach is validated by implementing the automated procedure using the example of a machine tool carriage. The semi-active component resulting from the optimization is then tested with machining tests.By achieving the defined goals, it will be feasible in the application to adaptively adjust a machine tool to any machining situation. The targeted adaptive change in the processing stability of the machine tool as described in this research project is an inexpensive, simple and promising solution.

• DFG Programme: Research Grants