Page 125 - Gear Technology Solutions

Figure 11: Generating profile crowning by changing the ratio of roll
with a second order function

9.6 Development Example

A circular profile crowning, as described in the last section, will create a motion
error with the magnitude of the relief. Gears with a conjugate flank center have a
low motion error and present the best possible load sharing between neighboring
teeth which reduces the root bending strength. The conjugate flank center also
results in low flank surface stress which increases the surface durability. The
notion of achieving a conjugate flank center and yet have enough relief at the
boundaries of the teeth also reduces the noise excitation potential of a gearset
significantly. The solution of a conjugate flank center and reliefs at top and root
was found by defining three profile sections. The conjugate center section, the top
relief section and the root relief section.

Figure 12 shows a simplified example where the active working profile has no
crowning or modifications (drawn as a straight line in red). At the border of the
active profile towards the top and towards the root, a second order Modified
Roll relief motion is programmed which provides a limited profile crowning
without interfering with the idea of a conjugate flank center. This software
function was programmed in the design and optimization software as well as in
®
the machine control of all modern Phoenix machines.

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