Measurement method of tooth friction force for helical gears by laser displacement sensor

Tooth friction force between the mesh teeth is a non-negligible excitation source for gear vibration and noise. However, the accurate measurement of the tooth friction force in mesh is very difficult, especially for helical gears. In this paper, a method for measuring the tooth friction force in helical gears is proposed by using a laser displacement sensor. The tooth friction force is obtained based on the bending deformation and the bending stiffness of the output shaft in the direction of the friction force. System errors of the gearbox are minimized by preload and locking device, and the measurement error is compensated according to the geometric positional relationship of the output shaft with and without the action of the mesh force. Experimental measurement is carried out by using an example of helical gears and compared with theoretical model. Experimental results have been shown that the magnitude and trend of the tooth friction force by measurement are basically the same with the theoretical calculations, which illustrate the effectiveness of the measurement method. It is also observed that both the tooth friction forces from the measurement and the theoretical model change direction twice in one mesh circle.