A comprehensive virtual model is formulated to investigate the closed-loop dynamics of the electro-hydraulic actuator to be used for effective isolation of ground vibrations in machine tools applications. Closed-loop transfer function between ground motion and isolated machine response suggests that the actuator may effectively isolate ground vibrations for excitation frequencies of up to 30 Hz. Numerical investigations representative of typical floor vibration levels experienced by machine tools demonstrate that ground motion may be isolated by up to 80%. Preliminary investigations are promising and provide useful guidelines for testing the real system that is presently being prototyped at the Fraunhofer IWU. Poor transient response of the electro-hydraulic system may be overcome by implementing other advanced control strategies, which forms part of the planned future work. The machine was presently modelled as rigid; however it is necessary to test the system (virtually) with a flexible description of the machine. Since in the case of a flexible description of the machine, the desired point of interest where the vibrations are to be isolated is the tool point, which is different than the machine mounting location, the model may need adjustments to achieve effective isolation. Furthermore, the possibility of spatial distribution of ground vibrations that may potentially result in different levels of excitations at different mounting locations, each with a different phase, pose interesting and challenging questions for effective isolation strategies. These investigations are also planned as part of the future work. Because of their high passive stiffness, in the absence of external disturbances, the active machine mounts can also be used in the passive condition. Since the device can be used on demand, i.e. only when high disturbances are observed or when high precision is required, it offers an energy efficient and economical solution.
Dynamic modelling of an electro-hydraulic actuator to isolate machine tools from ground vibrations
2014
7 Seiten, Bilder, Tabellen, 12 Quellen
Aufsatz (Konferenz)
Datenträger
Englisch