Development of a Measurement Method of Contact Pressure between Gear Teeth Using a Thin-Film Sensor (Measurement of Pressure Distribution by Multi-Point Pressure Sensor with Shared Lead Films)

Abstract

In order to investigate the durability of the sliding surface of machinery, it is important to know the force acting on such parts and to evaluate stress distribution. Contact stress occurring on the surface of gear teeth is an important factor in determining bending stress on the gear teeth as well as load capacity. However, since the contact area of each gear tooth surface is extremely small, a conventional pressure sensor cannot be attached. For this reason, the authors developed a thin-film pressure sensor with a thickness of approximately 6μm for gear tooth surfaces by applying the same type of sensors which have been developed to measure oil-film pressure distribution in engine sliding surfaces, such as plain bearing and piston-pin bosses. A sensor with multi pressure sensing points connected by shared-type lead films was developed for narrow areas such as gear teeth surfaces, and can measure pressure distribution on the gear flank line when gears mesh together. In the results, the measured pressure was higher than the Hertzian pressure of line contact, and distributed unevenly in the axial direction. On the other hand, when the measured pressure was compared with Hertzian pressure of point contact, the calculated pressure was higher than the measured value. These disagreements seem to be caused by inexact gear geometry, nonparallel or uneven meshing and form of gear flank. In this study, details of the shape of the multipoint thin-film sensor, as well as the measurement results of pressure distribution are described.