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the 9 harmonic (line DM09) of this specific gear design causes noise problems
with +0.100mm pinion cone increase, then it can be tried if the variation of the Mi-
croForm input parameters can solve the problem.
16.16 Summary
Surface topography scattering has proven to reduce the tonality of gear noise
emissions. Depending on the applied topography scattering scheme, edge contact
and spacing variations were reported.
The obstacles of creating pitch variations, flank corner point deviations and indi-
vidual closed loop corrections for each tooth have been solved by using a sinusoi-
dal surface modification which depends only on the roll position (second level) and
amplitudes from tooth to tooth which follow a normal distribution. The machine set-
tings and the part program of a MicroForm pinion or gear do not change when Mi-
croForm is turned on. All modifications are calculated tooth by tooth by the Micro-
Form software, which runs parallel to the part program execution.
MicroForm surface modulations only depend on the roll position. The amplitudes
are zero at the center of roll position. The departure from the center of roll position
generates a sinusoidal deviation, which is zero at the tooth contact entrance and
exit point (toe and heel), which reduced flank corner variations. The amplitude at
the center of the toe half and the heel half of the tooth are different from tooth to
tooth and are controlled by a normal distribution.
The obstacle of pitch variations was resolved by using the sine function, which is
zero at the center of the flank. This solution was refined by introducing a dwell sec-
tion. It is noteworthy to mention that in applications with a dwell section the tonality
was even further reduced.
Grinding times do not increase if MicroForm is applied. Closed loop G-AGE cor-
rections can be applied the common way if parts are ground with MicroForm.
Instead of increasing the gear quality for noise critical luxury vehicles and espe-
cially for eDrive applications, a less costly and more effective way is the applica-
tion of MicroForm.
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