Strictly speaking,theworm surface of the hob must be an involute helicoid which possesses an intersectingcurve in axial plane convex.

• 严格地说,渐开线齿轮滚刀的基本蜗杆曲面应是渐开线螺旋面,其轴断面内的截线是一条中凸的曲线。