当前,在普通螺纹基本牙型中,关于牙型半角误差中径当量f_α的计算,由于各个作者基于不同的出发点,因而得到各异的计算公式。经笔者的研究还发现,在牙顶和牙底高不相等的条件下,不仅f_α与牙型半角误差的正负符号有关,而且对于内、外螺纹亦应具有不同的公式。为使讨论具有普遍性,本文拟从螺纹具有不对称牙型及牙顶与牙底高不相等的一 Currently, in the ordinary thread basic profile, the calculation of the median equivalent diameter f_α of the tooth profile half-angle error is obtained by each author based on different starting points, thus obtaining different formulas. After the author’s study also found that in the tooth top and bottom of the tooth is not equal under the conditions of not only f_α and tooth half-width error of positive and negative symbols, but also for the internal and external threads should have different formulas. In order to make the discussion universal, this article from the thread with asymmetrical teeth and tooth top and tooth bottom height is not equal to a