The gearing machine tool of the model y3150e is modified and a new milling head is designed to cut the envelope tooth of the pinion using allelomorph method . a assembled drawing of clamp for cutting the tooth shape of circle - arc gear is also presented 对y3150e型滚齿机进行改造,设计出一新型的铣削头,利用对偶法加工小齿轮的圆弧包络线齿形;同时也给出了加工大齿轮圆弧齿形的夹具装配图。