The next field of manufacturers’ competition is the reduction of noise emission. The efficient way to reduce noise is to eliminate its source that is usually the vibration of some machine elements. The most efficient commercial method of R&D aiming vibration reduction is the experimental modal testing that identifies dynamical properties. The method is based on the measurement of the frequency response functions (FRFs), which requires the excitation of machine elements in wide frequency ranges. The test requires accurate broadband excitation. Commercial exciters have several drawbacks; one of these is the limited applicability for moving targets, rotating shafts. In the ERC Advanced Grant “SIREN” the pre-prototype of a ball shooter was constructed to excite spindles of machining centres by ball impacts. Experiments with the pre-prototype proved that the contact time is one order of magnitude shorter than that of standard impulse tests, while the force signal is near ideal: prall-free impulses with 30 kHz bandwidth were generated.
The ProExcer Proof of Concept project targeted and achieved improvements in several technical properties of the impact exciter for experimental modal analyses, by which the dynamical properties can be identified in a wider frequency bandwidth with improved accuracy. The unique property of the exciter is that it can be used even for moving targets, such as rotating shafts, milling tools, turbine blades. A novel optical sensor, for which our patent is pending, measures the spatial contact force vector generated by the projectile’s impact. A tailor-made millisecond precise shooting control unit was developed for accurately tuning the time instant of the impact. The unit enables the users to set the location of the impact on a moving object precisely; for example, the rotating milling tool can be hit at a specified one of the cutting edges. The laser aiming and the projectile dispenser modules were also improved.
None of the exciters available on the market has such exceptional properties. Exploitation actions towards a marketable impact exciter product are in progress.
