H3-VH-7-A siemens flender Helical speed reducer H3

Flender/Flender Gear Units/Helical speed reducer H3

city of the set-up and the ability to measure delicate components like slender tools and work pieces, it is drawback that static pre-load cannot be applied as in the case of relative actuator. The measured acceleration signals are converted into displacements by double integration in order to obtain the compliance frequency response ( ). The recorded force and displacement signals are then translated into the frequency domain by means of Fast Fourier Transform. The relative extremes of the compli- ance curve, at which the amplitude can often measure many times the static compliance, are the resonance points of the machine. Resonance of the machine structure, where there is large phase offset between the exciting force and the Fig. 8.6 Sample set-up on gear grinding machine8.3 Dynamic Machine Behavior 3 resulting displacement, may be critical for process stability. An unfavorable phase position with values below /C1can result in self-excited vibrations in machine tools used for cutting. Coherence is an important criterion for measurement quality; it indicates the extent to which measured displacements correlate with the applied force signals (ideal correlation: coherence 1; no correlation: coherence 0). Reliable measure- ments should therefore possess coherence values greater than 0.8 across the entire test frequency spectrum. If not, the measurement set-up should be checked. Figure 8.7shows dynamic compliance measurement set-up on the dressing spindle of gear grinding machine. 8.3.2 Modal Analysis The rst step in modal analysis is to approximate the geometry of the machine in mesh structure. The nodes of the mesh represent measuring points at which displacements of the individual machine components will subsequently be detected in three orthogonal coordinate directions. three-dimensional application of force to the machine, relative to the tool and work piece, is preferable in order to include all the resonant frequency modes of the structure in the anal