公法线法、圆棒法和弦齿厚法是测量圆柱齿轮齿厚的几种主要方法。关于这些方法的测量和计算问题,在文献中都有详细的介绍,但关于它们的精度问题,目前很少有文献作过全面的分析,而仅有一般的说明。例如,在测量公法线长度时,所跨齿数最好选得使量具的测量面与齿面接触在分度圆附近。但为什么要接触在分度圆附近,若不接触在分度圆附近对测量精度有何影响?又如 The common normal line method, the round bar method and the chord tooth thickness method are the main methods for measuring the tooth thickness of the spur gear. The measurement and calculation of these methods have been described in detail in the literature, but there are very few studies on the accuracy of these methods, but only a general description. For example, when measuring the length of a common normal, the number of teeth spanned is preferably such that the measuring surface of the measuring tool is in contact with the tooth flanks near the indexing circle. But why do you want to touch near the dividing circle, if you do not touch in the vicinity of the dividing circle on the measurement accuracy? Another example