Besides the relatively lengthy lead time, and despite the fact that the tooth profile is defined through its pressure
angles, 3D drawings of the gears cannot be produced. This is due to the difficulty of capturing the entire curvature of
the gear face from the outside to the inside diameter. Because of this difficulty, 3D quality control and FEA analysis
under load are difficult and must be accomplished through classical analysis that incorporate pinion bending stresses,
gear tooth shear stresses and compressive stresses between pinion and gear teeth. Due to some of these
challenges, these gears have maintained a niche status with the industry.
This paper will present a novel work for Spiroid® and worm gears that mathematically calculates the gear tooth profile
in terms of the geometry of the cutting tool (hob) and the machining setup. Because of their similarity, the work was
also expanded to spiral bevel gears. We have developed software to plot the gear tooth when the parameters of the
geometry of the tool and machining setup are entered. The gear tooth shape can then be altered and optimized by
manipulating the input parameters until a desired tooth profile is produced. In effect, the result will be designing the
hob and machining setup for best gear tooth profile on the computer. Afterward, the generated gear tooth data are
entered into CAD software to generate a true 3D model of the gear. The tool path will also be generated from the
data for CNC machining beside hobbing.