Development of the easy set-up and in situ automatic gear diagnostic system using a laser beam

We developed a method which can diagnose damage on a gear tooth surface by using laser beam without a rotary encoder. This method is as follows: 1) The tooth bottom, the tooth tip and their two medians are detected by the differentials of the laser reflection data. 2) The gear rotation speed is calculated with these four positions, and interpolated according to the rotation fluctuation. 3) By using the calculated gear rotation speed, the measured data can be converted corresponding to the gear rotation angle. Thus we diagnose gear tooth surface damage without being influenced by rotational fluctuation. We did diagnosis experiments and we made contour maps show diagnosis accuracy. From these maps, we got the following conclusions: 1) The accuracy of damage diagnosis is the same level regardless of the presence or absence of a rotary encoder. 2) The cycle of rotational fluctuation hardly affects the accuracy. 3) Bigger fluctuation amplitude makes the range accuracy worse, however the position accuracy improves.