Evaluation of Noise of Strain Wave Gearing by Vibration Measurement

Abstract

This paper deals with the radiated noise of strain wave gearing, which is a kind of K-H-V type planetary gears having features of light weight and high reduction ratio. The vibration of the Flex Spline (F/S), which is an element of strain wave gearing shaped like a thin circular cup, is considered to be a main cause of the noise. Theoretically, the magnitude of sound power is expected to increase in proportion to the square of the amplitude of the displacement of the F/S in the radial direction. The displacements in 3 models are calculated using FEM. The vibration of the F/S and the sound power are measured using the fixed-F/S experimental apparatus. It is confirmed that the relationship between the vibration of the F/S and the sound power agrees well with the theory, and that the vibration of the F/S is the main cause of radiated noise. Moreover, the radiated noise with various rotary speeds, loaded torques and assembly errors is measured and examined. The influences of rotary speed and torque are explained by the noise-generation mechanism on the basis of the velocity amplitude of the F/S. The noise becomes large with the increase of assembly error, but the amplitude of displacement is not increased. This is confirmed by the resonance between the F/S and experiment apparatus.