Abstract
We developed a new diagnostic method by using a laser beam. First, the tooth surface is irradiated by a zonal laser beam from oblique direction, and then an irradiated laser beam line is shifted along the height of the tooth according to gear revolution. The variations of laser reflection between the initial and the present conditions are compared, and it can estimate the condition on the tooth surface. Next, we developed the method to scan the length of the pitting area from the laser reflection data using a computer. To put this method into practical use, the laser sensor was fixed in the gearbox, and the laser reflection from the lubricated gear was measured. These experiments were carried out under the condition of force-feed lubrication. As a result, this method could detect all occurrence of the pitting in the dry condition. To improve the accuracy of the detected length of the damage area, the definition of the value of the first-stage threshold and smoothing of the different data was important. Furthermore, to apply this method to a helical gear, we made the three-dimensional model which located the relation between the helical gear and the laser sensor, and derived the conditional equation that the helical gear can be irradiated by the laser sensor along the tooth trace of the helical gear. By using this equation, we can diagnose the helical gear as well as a spur gear.
