A Novel Taper Design Method for Face-Milled Spiral Bevel and Hypoid Gears by Completing Process Method

For the face-milled spiral bevel and hypoid gears by the completing process method, in order to ensure that the tooth thickness and the tooth space width change in proportion to the cone distance, a novel taper design method is proposed. After the computation of blank dimensions of a gear pair according to ISO standard, the root angle of the wheel and the root angle of the pinion are redesigned based on the machining principle of the completing process method. Thus, the redesigned mean spiral angles of the wheel concave and convex tooth surface can be both equal to the original designed mean spiral angle of the wheel; likewise, the redesigned mean spiral angles of the pinion concave and convex tooth surface can be both equal to the original designed mean spiral angle of the pinion. By this, the ratios of the wheel tooth thickness and tooth space width to the wheel cone distance are more stable, and the ratios of the pinion tooth thickness and tooth space width to the pinion cone distance are more stable, too. Finally, this method is applied to a face-milled spiral hypoid gear pair, and the redesigned spiral angles of the wheel and the pinion are equal to the original designed mean spiral angles. For the wheel, the ranges of the ratios of the chordal thickness and the chordal space width to the cone distance are reduced more than 39% compared with those modified by ISO standard; for the pinion, the ranges of the ratios of the chordal thickness and the chordal space width to the cone distance are reduced more than 45% compared with those modified by ISO standard.