一、几何形状及参数的选择1、基本形状:微深孔钻头(简称“微孔钻”)易于弯曲、折断,因而要采用工作部分细、柄部粗的阶梯形结构(图1)。2、钻心直径(do):do大,对提高刚性有利,而对排屑、减小轴心抗力及注入切削液不利,因此应同时兼顾。微孔钻一般取do≤0.4D(D为钻头直径)。3、容屑槽:容屑槽宽度与刃瓣宽度之比取1.3～1.5;为改善排屑条件,有时也可取2～4。4、横刃:麻花钻横刃承受着30～50%的 First, the choice of geometric shapes and parameters 1, the basic shape: micro-deep hole drill (referred to as “microporous drill”) easy to bend, break, so to use the working part of the fine, shank thick stepped structure (Figure 1). 2, Core diameter (do): Do large, to improve the rigidity of the beneficial, and the chip evacuation, reduce the core resistance and injection of cutting fluid adverse, it should take into account. Microporous drill generally take do ≤ 0.4D (D for the drill diameter). 3, chip flute: chip flute width and blade width ratio of 1.3 to 1.5; in order to improve the chip evacuation conditions, and sometimes desirable 2 ~ 4.4, horizontal edge: Twist Drill bear 30 to 50% of the