An Alternative Method for Evaluating Gear Tooth Surface Geometry Based on Synchronous Average of Vibration of a Gear Pair

Low noise and vibration in the gearing operation is always required. Inspection by measuring gear tooth surface is a common way to investigate the source of noise and vibration. However many problems probably occur during assembling procedure, or are attributed to the bearing condition of the tooth pairs that certainly cannot be detected when inspecting each gear separately. In this paper, the newly developed method to evaluate gear tooth surface geometry based on vibration measurement is proposed. This method can be done in field. Moreover measured vibration also relates directly with the tooth bearing condition. In this method, vibration of the gear pair is measured and processed by the synchronous averaging technique to extract only the signal of interest. Then the system transfer function obtained experimentally is applied to the averaged-meshing vibration to estimate vibration excitation. Consequently tooth surface geometry directly relating with the vibration excitation can be inversely evaluated. The effectiveness of this method was verified by many experiments done by measuring the vibration of helical gears with various kinds of tooth surface forms at various operating conditions. The evaluated vibration excitations were plotted in the polar coordinate. The changes of amplitude and phase angle of the second order components were found to be suitable and could be used as an indicator to evaluate gear tooth surface form.