Conformity Factor In Wildhaber-Novikov Circular-Arc Gears

Abstract

Conformity factor, which is more rationally defined as the ratio of the area of contact to the active area of the flank of the mating teeth, is theoretically evaluated for Wildhaber-Novikov circular-arc gears, using Hertz’s theory of contact stress, without neglecting the effect of the difference in the profile radii of the pinion and wheel teeth, which is an important factor in fully-hardened gears. The variation of the conformity factor with the helix angle, pressure angle, ratio of the profile radii, module and the number of teeth follows closely the variation of load-carrying capacity per unit face-width of these gears and hence, from this study it is concluded that conformity factor is a more rational index on which the selection of the profile and material parameters should be based. This study of the conformity factor, for the particular profile geometry, indicates 7.5 to 15.0 deg as the suitable helix-angle range for achieving maximum load-carrying capacity per unit face-width.