图示的钻头很适宜加工铸件孔。用该钻头加工的孔,不仅尺寸精确,而且还可得到较小的表面粗糙度。该钻头制造方便,调整也相当容易。其结构为:端部开有缝槽的圆形钻柄上嵌入两块矩形硬质合金刀片、为了用内六角螺钉将刀片夹紧在适当的位置上,槽下端的中心部位必须具 The illustrated bit is ideal for machining castings. The holes machined with this drill bit are not only dimensionally accurate, but also result in smaller surface roughness. The drill is easy to make and easy to adjust. The structure is as follows: two rectangular carbide inserts are embedded on the circular shank which is provided with a slot at the end, and the central part of the lower end of the groove is required to be clamped in place by the hexagon socket screw