(1) To measure the tooth thickness of the indexing chord and the tooth height of the indexing chord. The characteristic is that when measuring the tooth thickness of the indexing chord, the addendum circle should be used as the measurement benchmark, but the accuracy of the addendum circle is not high when the gear is actually working. , so the design and machining accuracy of the addendum circle are generally low, which affects the measurement accuracy of the chord tooth thickness.
(2) The characteristic of measuring the thickness of the fixed chord tooth and the height of the fixed chord tooth is that the calculation of the measured value is only related to the module and tooth profile angle of the measured gear, and has nothing to do with the number of teeth. In addition, the module and profile angle of the standard gear have been Standardized and easy to calculate.However, when measuring the tooth thickness of a fixed chord, the addendum circle should also be used as the measurement benchmark, which affects its measurement accuracy.
(3) Measuring the length of the common normal is characterized by simple measuring tools, convenient and accurate measurement, and the manufacturing error of the tip circle has no effect on the measured value of the common normal length.
The latter two measurement methods are used in actual production