Page 184 - Gear Technology Solutions

outer diameters and which can perform a roughing and finish grinding cycle. The
most common Curvic coupling grinders are the Gleason No. 887 (and 887 CNC)
and the Gleason No. 888 (and 888 CNC). The Curvic coupling grinders use a re-
verse pulse cycle for roughing, where the grinding wheel moves forward a certain
pulse stroke and immediately withdraws the grinding wheel about 50% of the for-
ward stroke amount. Roughing the slots stops 0.254mm from full depth. In the fin-
ishing cycle a different grinding wheel specification, with a finer grit and a forward
pulse is used. The wheel pulses forward and sparks out before pulsing again for-
ward. After 4 to 5 forward pulses, a slot is finished. No. 887 and 888 grinders have
a grinding wheel spindle quill which makes a fast pulsing possible, avoiding mov-
ing the substantial mass of the sliding base for each pulse. Dedicated Curvic cou-
pling grinders have a machine root angle adjustment of +/-90°. This freedom al-
lows for easy loading and unloading of large rotors with a crane and also makes it
possible to grind negative pressure angles.

For smaller Curvic parts, standard Phoenix cutting and grinding machines can al-
so be used. Instead of a reverse pulsing, Phoenix grinders use a forward pulsing
in combination with a Waguri eccentric spindle motion [5]. Grinding parts with
negative pressure angles is not possible with Phoenix grinders due to the limita-
tion of negative machine root angles at -6°.

12.5 Summary

Three of the most well-known face couplings have been discussed in this chapter.
Gleason has the only established two manufacturing processes for the manufac-
ture of Hirth couplings, Coniflex couplings and Curvic couplings.

Hirth couplings are designed for maximal strength with a fully rounded root, a
pressure angle of 30° and a duplex taper. There is no special Hirth cutting or
grinding process, which suggests that the Coniflex Clutch process is best suitable
regarding manufacturing speed, accuracy, surface finish and closed-loop manu-
facturing possibility of Hirth couplings.

The advantage of the Coniflex coupling manufacturing method to older methods
and to machining center solutions is the fact that a large size disk shaped cutter
can finish one flank in a single plunge, without the requirement of any stroke mo-
tion along the face width. This makes the Coniflex process very fast despite the
single flank cutting in a lower and upper cutting cycle. The advantage of the single
side cutting are the “unlimited” freedoms for pressure angle and tooth depth taper,
for example to duplicate Hirth couplings with a fully rounded root fillet, with the
same radius along the entire face width.

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