Page 354 - Gear Technology Solutions

Figure 7: Maximal radii of curvature - modified approach

25.5 Summary

A rule for maximal cutting edge curved blade radii was developed in order to
create a guideline for gear engineers who design and optimize bevel and hy-
poid gears. The proportion between the measurement length (cutting edge
length minus tip edge radius minus Toprem minus Flankrem, if Toprem and
Flankrem are present) and the blade curvature radius is not only important for
the blade grinding, measurement and correction, but also relevant for the de-
sired profile correction. A radius of 1000mm on a measurement length of
10mm results in a crowning value in profile of 12.5mm. A radius of 3000mm on
a measurement length of 20mm results in a profile crowning of 17mm. These
values are customary for the application of profile crowning. If larger radii are
required, then the blade profile grinding and the measurement and corrections
are possible However, the absolute accuracy of the resulting curvature radii
might be outside of the given Tolerance, although the measurement report
shows them within the tolerance. This is basically not a real problem for the
cutting blades and the manufactured bevel gears, but if different GBX blade
measurement machines are in service in the same factory, this could lead to
unexpected profile variations from one tool life to the next.

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