Page 23 - Gear Technology Solutions

In the past the normal chordal tooth thickness was measured with tooth
thickness micrometers or Vernier calipers. Today, highly precise
measurements are conducted with coordinate measurement machines. The
only shortcoming for gear engineers which would like to close the loop
between gear design and the manufacturing results is the fact that the center
point of a CMM measuring grid is used to determine the tooth thickness angle
between the two flanks of a tooth (see Figure 7). If the tooth thickness angle
(in radiant) is multiplied by the radius value of the grid center point, then the
circular tooth thickness in the approximate transverse direction is the result.
Due to often different edge reduction at toe and heel as well as top and root,
the grid center point is neither exactly at midface nor in the center of the tooth
depth. Thus, the point where the tooth thickness was measured is not
matching the mean face pitch line location.

Figure 7: CMM tooth thickness measurement

In order to present solutions for the different documentation and quality
assurance purposes, three different cases of tooth thickness measurements
have been developed for the UNICAL Dimension-Sheet output. A new routine
in the flank form generation and a new Dimension-Sheet Applet working
together in order to generate different grid types for a tooth thickness
measurement which can be customized to all major public and company
specific standards.

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