The drill rod was designed not rotative,and the piston can turn around along with the chuck fixed on the spindle,so relative rotational movement between them takes place when the lathe runs,and the centre bore drilling was effected.

• 由于钻杆自身不旋转,而工件被夹持在液压卡盘上随主轴一起旋转,中心孔钻相对工件产生相对旋转运动,从而实现钻削功能。