这种丝锥(图1)与普通使用的丝锥相比较,不同之处主要在于:(1)减小了切削刃的前角r和切削锥后面鏟削量K(取r=5°～8°;K=0.5～0.75毫米),因而增加了切削刃的强度;(2)增加切削部分长度(取6个螺距),使切屑厚度减少到0.055～0.075毫米,因而产生的切屑很柔软,并紧紧地卷成螺旋形(图2),以利于排屑;(3)导屑槽采用左旋槽,使切屑 This tap (Figure 1) compared with the ordinary use of the tap, the difference is mainly: (1) to reduce the rake angle cutting edge and the back of the cutting chipping K (r = 5 ° ~ 8 ° ; K = 0.5 to 0.75 mm), thereby increasing the strength of the cutting edge; (2) Increasing the length of the cut (taking 6 pitches) reduces the chip thickness to 0.055-0.075 mm, resulting in chips that are soft and tight Tightly rolled into a spiral (Figure 2), in order to facilitate chip removal; (3) chip guide slot with left-hand slot, so that the chip