Method for Cutting Straight Bevel Gears Using Quasi-Complementary Crown Gears

In the manufacture of straight bevel gears, there is usually a need for some "trial-and-error" process by which a good tooth bearing is obtained. In this paper, a method for cutting straight bevel gears in which a trial-and-error process is not necessary is proposed. The method can be applied without the necessity of cutter modification or generator alteration. Each gear and pinion is generated by a newly introduced "quasi-complementary crown gear" instead of a conventional complementary crown gear. The quasi-complementary crown gear is a bevel gear whose pitch cone angle is 90° minus the root angle of the workpiece and whose tooth surface is a plane. The pitch cones of the quasi-complementary crown gear and workpiece roll with each other. Therefore, the ratio of roll between the crown gear and workpiece is expressed as a function of the root angle. The quasi- complementary crown gear produces a profile modification of the generated gear tooth. Gears made on an experimental basis showed a good tooth bearing as expected