Page 128 - Gear Technology Solutions

created by the slide drop. This drop is the result of top-root relief and is
required to ensure a smooth transition of the load transfer from one pair of
teeth to the next. Traditional straight bevel gears have transmission errors
between 300 and 600mrad. State of the art differential gears, manufactured
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with the Revacycle method or by forging, show motion errors larger than
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1000mrad. The comparison to 25mrad motion error amplitude with Coniflex Pro
differentials gives an idea about the substantial improvement of the new
differential gear cutting process.

Differential gears are cut with the so-called “Roll Only Process”. This process is
fast and requires only one roll motion per flank which repeats after indexing to the
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next slot. Coniflex Pro gears are cut in a high speed, dry PowerCutting process.
The cutting blades can be two- or three-face ground and are preferably all-around
coated. Flank form geometry, indexing error and surface finish of this process are
excellent.

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Figure 15: Coniflex Pro surface roughness depending on the roll rate

In Figure 15 the results of surface roughness tracing are shown. A standard
roll rate of 15°/sec delivers the surface roughness in the upper chart of Figure
15. The value Ra = 0.51mm equals a good grinding quality. Even with the
faster roll rate of 30°/sec (lower chart in Figure 15), a Ra of 0.83mm is
achieved, which still is consistent with grinding quality.

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