Abstract: An analytical method for calculation of conformal mapping function of the tooth profile of evolvent gear is given. Not only the calculation is convenient, the accuracy of the mapping is high, but also the form of the mapping function is simple. By means of above-mentioned result, the analytical formula for the calculation of the displacement of the middle point of the contact zone of the tooth is given. By a calculative example, the uniformity of the calculative datum and, the test datum is illustrated.

Key words: Coaformal mapping method, Evolvent spur gear, Tooth deflection