螺纹底孔的加工,一般是先钻孔后倒角,工作效率较低。在大批量生产时,则使用阶梯钻,钻孔、倒角一次完成,但阶梯钻价格贵、刃磨困难。为此,我厂设计了一种组合刀具(附图)。组合刀具是由普通麻花钻和空心锪孔刀组成。调节套3一端为调节螺纹,另一端为带有1:10锥度的螺纹,并沿轴向开有四个槽,使之具有弹性,锪孔刀5壁厚一般为1.5～2.5mm,开有两个刀齿,且沿刀体外表面开有螺旋沟,起润滑 Bottom thread machining, chamfering is generally the first drilling, lower work efficiency. In mass production, the use of ladder drilling, drilling, chamfering done, but the ladder drilling expensive, grinding difficult. To this end, I plant a combination of design tools (with photos). Combination of tools is made of ordinary twist drills and hollow countersink knife. One end of the adjusting sleeve 3 is an adjusting thread, the other end is a thread with a taper of 1:10, and four grooves are axially opened to make it flexible. The wall thickness of the hole cutter 5 is generally 1.5-2.5mm, Two teeth, and along the outer surface of the cutter body with a spiral groove, lubrication