Gear Cutting Tools
Hobs - Torion
Hobs - Torion
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Explanatory notes<br />
Hobs for internal gears are designed<br />
for a specific gear. The<br />
measurements for the maximum<br />
and the minimum cutter diameter<br />
and the maximum cutter width<br />
must then be taken into account,<br />
for which the internal hobbing<br />
head is dimensioned.<br />
ln the case of internal gears with<br />
large profile displacement, the<br />
maximum permissible cutter width<br />
may be insufficient for cutting the<br />
complete teeth, if the hob is dimensioned<br />
in the usual way. It is<br />
then necessary to fix the module<br />
and the pressure angle of the hob<br />
differently from those of the internal<br />
gear.<br />
On the hob, one tooth is defined<br />
as a "setting tooth" and marked<br />
accordingly. The cutter must be<br />
positioned on the hobbing machine<br />
so that the setting tooth is<br />
when new placed in the "machine<br />
centre". Although the setting tooth<br />
will shift in the axial direction when<br />
the hob is reground, it is not necessary<br />
to correct the position of<br />
the hob determined in the new<br />
condition and fixed by spacers.<br />
The hobs offered for finishing<br />
internal gears are only to a limited<br />
extent suitable for roughing. Bearing<br />
in mind the tool costs, relief<br />
turned hobs with a lead matched<br />
to the workpiece should be used<br />
for roughing.<br />
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