ANALYTICAL GEAR MEASUREMENTS
Analytical gear measurements are used to check for the
compliance of particular gear tooth parameters with the pertinent design
specifications or, for deviations, to measure the characteristics and extent of
the error.
The analytical or discrete measurement of gear tooth
dimensions may be needed for various reasons, which may be related to the
expected functional performance of the gears or to gear manufacturing process
control. A few examples of the purposes of analytical gearinspection are:
1. To determine the sources of improper gear operation,
either experienced in use or discovered by functional checking.
2. To inspect the accuracy of specific gear tooth parameters,
for example, involute profile, tooth spacing or blacklash, errors that may be
mutually compensating or for other reasons not revealed by functional checking,
but that are still critical in certain applications, such as where the gear has
an indexing role, and is required to produce incremental rotational movements
that are rigorously proportional to the input motion.
3. To provide guidance in the proper setup of gear manufacturing
machines, thereby avoiding the production of faulty gears.
4. To check the appropriate execution or sharpening
of gearcutting tools, such as hobs and gear cutters.
5. To determine the effects of the applied heat-treating processes
so that appropriate modifications in work material or procedures can be made,
when needed, or compensating adjustments can be applied to the tooth form
design of the soft (nonhardened) gears.
The gear tooth parameters that are commonly inspected by
analytical measurements and the instruments used for the individual types of
inspection procedures are reviewed in Table 17-1. The listing of this table
does not indicate an order of importance or frequency of use; the types of
analytical gear tooth measurements to be carried out are determined according
to the applicational or technological requirements of the gears.
The subsequent detailed discussion of each measurement type
and examples of the instruments used will follow the order of that table.
TABLE 17-1. PARAMETERS AND
METHODS OF ANALYTICAL GEAR MEASUREMENTS
