Finish Hobbing of Gears with Accurate Tooth Profiles

Abstract

In order to obtain accurate steel gears by hobbing, not only are accurate hob and rigid hobbing machines necessary, but tooth surface smoothing is also required. Recent studies have shown that a very smooth tooth surface can be hobbed with cemented carbide or cermet-tipped hobs for hardened and tempered gears. In this report, the tooth profile errors of steel gears by finish hobbing are investigated and the possibility of obtaining highly accurate gears by hobbing is discussed. As a result, it is clarified that the tooth profile errors of steel gears are mainly caused by the geometrical errors of hobs and the setting eccentricities of the hobs tested. Therefore, if using accurate hobs and hobbing machines with sufficient stiffness and selecting suitable cutting conditions, steel gears can be accurately manufactured by hobbing.