变位蜗杆传动中，如变位系数选取过大，可能导致蜗轮齿顶变尖，造成蜗轮强度下降，甚至磨倒掉屑，造成严重磨损，使传动过早失效．指出沿蜗轮齿宽最小齿顶厚出现的位置，推导了计算该最小齿顶厚的方法，并给出设计实例． Variable displacement worm drive, such as the displacement coefficient selection is too large, may lead to tooth tip sharp tip, resulting in decreased strength of the worm, and even grinding out the crumbs, causing serious wear and tear, so that the transmission failure. It is pointed out that the minimum tooth top thickness along the tooth width of worm gear appears and the method of calculating the minimum tooth top thickness is deduced and the design example is given.