Gear error induced impact in a multiple take-off textile drive system operating under light loading
thesisposted on 07.02.2011, 09:49 by David Trueman
A combined theoretical and experimental investigation is made into the causes of premature gear failures which had occurred in the complex and lighly loaded gear trains of an industrial textile machine. A comprehensive review of previous relevant work identifies the problem as one of torsional vibratory impact excited by gear transmission errors. An extension of the dynamic stiffness method is developed for the analysis of forced vibration response due to relative displacement, harmonic excitation imparted by transmission error components. The technique is then applied to a generalised mathematical model of the complete machine in which typical production distributions of gear error magnitude and relative phasing are inserted. Gear-tooth dynamic loads are computed at every mesh for a number of different machine configurations over the operating speed range. The influence of selected inertia, flexibility and damping elements is demonstrated. A novel technique employing magnetic drums is devised and evaluated for the direct measurement of-relative motions in a meshed pair of oscillating gears. Automatic compensation is provided for transmission error and mounting eccentricity. A further direct technique is reported for the detection of tooth impacts and is based on the change in electrical resistance between meshing teeth as the contact pressure varies. Measurements in a multi-gearbox experimental rig demonstrated that the gears described non-linear motions, involving excursions through the backlash and heavy impacts on both drive and reverse faces. Theoretical predictibns of dynamic loading distribution within machines show reasonable compatibility with patterns of gear failure recorded in service, even though the analysis does not allow for system non-linearities. Machine design considerations are examined in retrospect from a dynamics standpoint. Past and present designs are appraised and possible alternatives to these are briefly discussed. Finally, the salient factors identified in the investigation are summarised and recommendations made for future work.
- Mechanical, Electrical and Manufacturing Engineering