Page 170 - Gear Technology Solutions

Figure 2: Cutting channel rotation to achieve a Duplex Taper

The design of a duplex taper is shown in Figure 2. The initial reference chan-
nel is defined at the center of the face width, with a parallel root width. Then it
is rotated about the channel rotation axis until a slot width reduction at the toe
and a slot width increase at the heel (measured in the pitch reference plane) is
achieved. The slot width change results in a slot width taper along the face
width, which is proportional to the circumference of the pitch cone at the re-
spective face width position [2].

The duplex taper makes it possible to machine the Hirth coupling slots, each in
a single stroke with a disk milling cutter with cutting edge angles, matching the
pressure angle of the teeth. The root is fully rounded with a constant radius
between toe and heel.

Topland chamfers cannot be produced with a special Flankrem design on the
blades of the milling cutter because of the tapered depth slots. If topland
chamfering is required, then it has to be performed in a secondary operation.

In Figure 3 there is a principal graphic of a Hirth coupling with the basic design
parameters shown. The name Hirth only stands for the coupling design, there
is no dedicated manufacturing process.

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