Page 260 - Gear Technology Solutions

In an initial development step, the possibilities of selective crowning have been
used in order to convert the gearset in Figure 9 to a conjugate basis for the
following selective crowning development. The result is the approximately con-
jugate Ease-Off in Figure 10, which shows a full contact bearing and a low
motion error.

The first step in the selective crowning development is the implementation of
blended Toprem in pinion and gear. The Toprem depth is chosen such that the
Toprem relief becomes visible in the Ease-Off graphics. The Toprem radius is
selected by trial and error, until the relief amount visible in the Ease-Off is
about 0.025mm. The results of this first step are shown in Figure 11.

In the second step, a heel end-relief was applied to the coast and drive side
of the ring gear flanks. The relief surfaces are second order functions with a
section length of 20% of the face width. The relief amounts are 25mm on the
coast side and 10mm on the drive side (see Figure 12). Tooth contact and mo-
tion error improved on the drive side significantly, where the cost side appears
to need more work.

The third step is the application of UMC toe sections on the coast and drive
side of the pinion flanks as shown in Figure 13. The relief function is of the
second order, the section length is 25% of the path of contact length and the
relief amount is 25mm on coast and drive side. This correction was made in
order to generate more toe relief at the path of contact exit point.

To balance drive and coast side Ease-Offs at the heel, a UMC heel relief was
added in the fourth step with a second order relief function. The section
length is 30% and the relief amounts are -25mm on the coast side and +25mm
on the drive side (see Figure 14).

In order to improve the contact pattern and reduce the motion error on the
coast side, a negative profile crowning of -5mm was added in the fifth step as
documented in Figure 15.

In the sixth step (Figure 16), a small pressure angle change on the coast side
was made to achieve more conjugacy in the toe area.

The existing Ease-Off twist at the coast side was eliminated in the seventh
step by adding 35mm heel section relief as shown in Figure 17.

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