Gear Generating Processes

Gear Generating Processes

Gear Generating Processes - Most widely used in large-lot and mass production of gears are various versions of the generating processes:

(a) Gear hobbing,
(b) Gear shaping, and
(c) Rack planning.

In generating process, the cutting tool (cutter gear) meshes with the gear blank and the teeth are developed on the blank by the relative coordinated rolling motion of the cutter and the blank. The cutter gear and the gear blank are attached rigidly to their corresponding shafts, and the two shafts must be interconnected by suitable gearing so that the cutter and the blank rotate positively with respect to each other and with the same pitchline velocities.

To start cutting a gear, the cutter gear is reciprocated and fed radically into the blank between successive strokes. When the desired tooth depth has been obtained, the cutter and blank are then rotated slightly after each cutting stroke.

The generating method provides high productive output and accuracy of gens being cut, and also makes it possible to use one cutting tool for machining gears of a given module with a varying number of teeth.