Study on Planetary Gear Drive Using Internal Gear Easily Ground

A planetary gear drive having the internal gear that can be easily ground is developed. This gear drive is composed of the three parts; the internal gear finished by the grinding wheel with a trapezoid profile, the planet gear conjugate to the internal gear, and the sun gear conjugate to the planet gear. In this paper, a method to design the gear tooth without undercutting and without tooth tip pointing on the planet and sun gears is shown and the effect of the center distance on the transmission error is investigated. Three kinds of planetary gear drives using the internal spur gear finished with the trapezoid grinding wheel, the internal involute spur gear, and the internal helical gear finished with the trapezoid grinding wheel were designed, made. As the result of loaded running tests, it was found that vibration and noise of both planetary gear-drives with the spur gear teeth are almost the same, and the gear drive with the helical gear teeth brings lower vibration and noise.