AGMA 22FTM12 PDF

After a short introduction about the advantages of herringbone gears (no gap between the two gears) and double helical gears (with a gap) and their areas of application, the article goes into detail on the properties and limits of manufacturing processes for machining these gears. The technology data and the gear quality achieved are listed for selected machining examples so that the user is provided with helpful information for daily practice.

For green machining, the focus is on gear shaping and 4- or 5-axis milling, because these two methods replace gear planning (otherwise known as rack-type shaping). Due to the increased quality requirements nowadays, more of these herringbone gears and double helical gears have to be hard finished. From an economic point of view, only 4- or 5-axis hard milling can be used for herringbone gears. Profile grinding has become established for double helical gears if they have a certain gap width.

Due to the development of new and high-performance cutting materials, grinding worms with a very small starting outside diameter of 55 mm can also be used. This makes continuous generating grinding a real alternative to profile grinding for the module range up to 5 mm. Electroplated as well as vitrified-bonded CBN and sintered corundum abrasives in triangular or rod-shaped form are used. Generating grinding has the following advantages over profile grinding:

– Significantly faster grinding times

– More robust against stock deviations and heat treatment distortions

– Lower risk for grinding burn

– Economic manufacturing of topological modifications, like the generated end relief (GER), twist free grinding (TF), etc.

– Higher apex and indexing accuracy

– Very high single and cumulative pitch quality due to the continuous process

– Potential for fine grinding and polishing for improved surface roughness

This will be the first time that the technology development of continuous generating grinding of double helical gears will be presented.