Page 73 - Gear Technology Solutions

analysis of the Dimension sheet data by a gear engineer. For example, tip relief or
Toprem allow for slightly larger than recommended radii.

5.2 Maximal Cutter Blade Radius

The first highlighted line in Figure 1 shows the maximal cutting-edge radius the
outside and inside blade can have in order to machine a fully rounded root. This is
the maximal radius which can be used without the risk of a “Gothic arc” blade tip
and root bottom. The condition of using the maximal possible radii which fills out
the entire root with a theoretically perfect blend with the flank surfaces is visualized
in Figure 2 and can be calculated as follows:

WROW = WP/[(cosa 1+cosa 2)–(1-sina 1)•tana 1–(1-sina 2)•tana 2]

Whereas:
WROW… Blade edge radius
WP… Blade point
a 1… Inside blade pressure angle
a 2… Outside blade pressure angle

Figure 2: Maximal blade edge radius for fully rounded root

5.3 Mutilation Limit

Mutilation happens if the clearance side of a blade leaves a scratch or even a
notch in the opposite flank, which is not cleaned up when the opposite flank is
generated. The cause of mutilation is a too large blade top width and/or a sharp
corner on the clearance side blade tip as shown in Figure 3. The mutilation effect
in Figure 3 will slide higher up into the flank surface while generating the profile.

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