Theory error of cutting face gears with sphericity hob

A scheme for cutting face gears with a sphericity hob and reconstructive hobbing machine was proposed. The basic worm helicoid surface of sphericity hob was deduced, and the coordinate systems for cutting face gears were established. The error difference surface research indicates that theory surface error of the face gear using sphericity hob is very small. The forming error of hobbing is much less than that of slotting cutter. Tooth contact analysis (TCA) indicates that the contact path position and direction are consistent with the theory results, and the transmission errors curve with the new method is favorably parabolic. This research finds a new method for machining face gears, and expands the application scope for the sphericity hob.