Die-Rolled Noncircular Gears : Part 1, on Elliptic Gears of Aluminium

Abstract

Noncircular gears have been generally manufactured by cutting machines, such as hobbing machines or gear shapers fitted with special equipments. As the equipment, however, are very complicated, it is considered hard to cut the teeth of noncircular gears. Then, the author thought of an easier way of manufacturing noncircular gears. It is same way of rolling, not cutting, as in that of circular gears. In this research, a simple equipment was made for trial to roll elliptic gears, the most familiar ones of all the gears. First a die holder with two dies was fitted with the tool rest of a lathe, then the tool rest was pushed toward the gear blank by a spring to press the dies into the gear blank, which was rolled into gears. The two types of elliptic gears were made by the above mentiond experiments ; one is with module 1 and the number of teeth 75, and the other with module 1.25 and the number of teeth 60. The major axis is 93.72mm long and the minor, 54.12mm long for both cases. Aluminium was used as the material.