Page 400 - Gear Technology Solutions

If the same cutting process is used (face hobbing or face milling) between the
members of one part family and if the cutter type and cutter hands of rotation-
are also identical between the members of this part family, then the fact that
each member requires a slightly different blade geometry seems to unneces-
sarily increase the cost of blade profile grinding and cutter head building as
well as the logistical cost of cutter head handling between tool room and
manufacturing machines.

Consolidations of the blade geometries of a number of jobs which is in most
cases below 10 has already been done in the past. The problem of the past
consolidation procedures was the high amount of manual intervention required
by a gear engineer. The past software only copied the cutter data of one job,
which was selected as master job, in the data file which contains the machine
settings, cutter geometry and kinematic data (e.g. called Special Analysis File
or abbreviated SPA-file).

After copying the cutter data into the job specific data files, the gear engineer
will have to check each consolidated job for tooth thickness, cutting depth and
tooth contact. All those three geometrical properties will, in a realistic consoli-
dation case, be far away from the required values. The term “far away” refers
to the impact of those geometrical properties on the physical properties of the
gearsets which causes the following deficiencies:

• Unacceptable tooth contact which will lead to edge contact
and increased surface and root bending stress
• Increased operating noise
• Reduced efficiency

Tooth contact pattern, tooth thickness and tooth depth can be corrected within
limits for each job of the consolidation variety individually by employing ma-
chine settings and machine kinematics.

Depending on the results of the analysis software, the blade parameters like
protuberance (Toprem), edge radius and cutting-edge curvature radius have to
be evaluated and changed. All those blade geometry related parameters can
only be changed on all jobs simultaneously because the cutter and blade data
of all jobs have to be identical. The common procedure is to change one pa-
rameter for the job on which it had the most negative influence and then apply
this change to all cutters and blade data of the remaining jobs. After those
changes, all the analysis have to be repeated, which commonly pinpoints now
a different job which shows deficiencies caused by the just changed parameter
or by one of the remaining parameters. Figure 2 visualizes the complex con-
solidation task which also considers the cross influences between the pinion

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