Zusammenfassung
2016 The Authors. Large-scale machine tools for the manufacturing of large work pieces, e.g. blades, casings or gears for wind turbines, feature pose-dependent dynamic behavior. Small structural damping coefficients lead to long decay times for structural vibrations that have negative impacts on the production process. Typically, these vibrations are handled by increasing the stiffness of the structure by adding mass. That is counterproductive to the needs of sustainable manufacturing as it leads to higher resource consumption both in material and in energy. Recent research activities have led to higher resource efficiency by radical mass reduction that rely on control-integrated active vibration avoidance and damping methods. These control methods depend on information describing the dynamic behavior of the controlled machine tools in order to tune the avoidance or reduction method parameters according to the current state of the machine. The paper describes the approach for a general pose-dependent model of the dynamic behavior of large lightweight machine tools that provides the necessary input to the aforementioned vibration avoidance and reduction methods to properly tackle machine vibrations. The paper starts with an overview of the state of the art of the pose-dependent dynamic behavior of machine tools followed by the most common methods for vibration avoidance and reduction. Based on the results of an experimental modal analysis of a lightweight machine tool structure, the relevant pose-dependency is shown and the relevant parameters to derive the dynamic behavior are deduced. Then, a general model structure to model the machine tool's dynamic behavior is introduced. After updating the model parameters to different discrete machine poses the dynamical behavior of the model and the real machine tool structure are compared. Finally, it is explained how the model contributes to the actual vibration reduction of lightweight machine tools.
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