Page 347 - Gear Technology Solutions

24.7 Summary

Vector feed was developed to achieve a plunging with low power draw of the cut-
ting machine and low vibration and smooth cutting during the plunge. Equally im-
portant in this development was to obtain low blade wear, which is balanced be-
tween outside and inside blades. Of course, these physical properties are not con-
tradicting each other. Optimal cutting conditions exist when the chip load between
outside and inside blades is balanced and if the power consumption during plung-
ing is at a low level. This also goes along with a cooler cutting process.

The development of different vector feed concepts was triggered by the high
®
speed, dry PowerCutting with coated carbide blades, where the chip removal
mechanics are different compared to wet cutting with high-speed steel. PowerCut-
ting requires a certain temperature between cutting edge and the rolling off chip.
However, this heat has to be transferred into the sheard off chip and removed
from the machine, such that the cut gears and machine components reach, after
cutting 5 parts for example, a semi-steady state temperature. In the course of cut-
ting through the tool life of the blades, a certain steady temperature increase of the
cut gears can be noticed, which above 120°F indicates the end of the tool life.

Vector feed not only has its place in feeding a cutter into a work piece blank but
also during the withdraw of the cutter from the slot. In Formate cutting, the same
vector direction as for plunging is used. For generated parts, a special vector for
withdraw is calculated and applied. Due to the roll motion, for example, for a pinion
from toe to heel, the outside or inside blades could clip the finished flank surfaces
if the withdrawal happens along the Z-axis of the Phoenix machine. A withdrawal
in cutter axis direction provides, in most cases, the optimal vector direction.

In the case of straight bevel gear cutting with peripheral Coniflex Plus cutters, spe-
cial withdraw vectors for lower and upper cutting are calculated for the machine
summary to minimize additional unwanted material removal with the cutting edge
and the clearance side of the blades (see also Figure 6).

24.8 Literature

[1] Pitts, L. “Design and Development of Bevel and Hypoid Gears using
the Face Hobbing Method”, Company Publication, The
Gleason Works, Rochester, New York, June 1997

[2] Stadtfeld, H.J. “The Optimal High Speed Cutting of Bevel Gears”, Company
Publication, The Gleason Works, Rochester, New York, June
2007

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