In order to describe contact stress accurately, on the basis of Hertz formula, contact stress formula has been deduced which is more fit to the planar enveloping hourglass worm gear according to the mesh and tooth-form character. 为了更准确地描述齿面接触应力,在Hertz公式的基础上,结合平面包络环面蜗杆传动的啮合特性和齿廓形状,探索平面包络环面蜗杆传动瞬态接触应力的计算方法。