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of roll (midface) and toe and the heel dwell section DHeel between center of roll
and the heel. When the machining takes place within the two dwell sections, the
second level function is turned off and no modification to the flank surface is ma-
chined (second level function has zero amplitude withing the dwell sections). The
preferred amounts of the toe and heel dwell sections are between 0° and 4° of roll.
16.15 Practical Results
MicroForm is today already in production in many automotive axle factories. The
practical results have proven that the two-level flank form modification method re-
duces the tonality of bevel and hypoid gearsets and leads to quieter appearing
operation of vehicle drive axles. It also was confirmed that indexing errors are low
and no failures due to edge contact have been recorded. This proves that the
strategy of a first level function, which controls the tooth-to-tooth modulation mag-
nitude (second level) works well and eliminates the typical problems reported be-
fore the MicroForm development.
Figure 16: FFT results, baseline (top) and MicroForm modified (bottom)
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