标准麻花钻切削条件最差的是钻芯的横刃处,由于横刃前角为大的负值,造成钻头工作不稳定,并产生很大的轴向力。而且标准麻花钻的主切削刃长,切削宽度大,各点的切屑流出速度相差很大,切屑占有空间大,排屑不畅。人们一直在寻求缩短麻花钻横刃和减小主切削刃的方法。虽然群钻采用了更为先进的修磨方法,但仍不能达到理想效果,且刃磨复杂,不利推广。 Standard twist drill cutting conditions worst is the chisel edge of the chisel, due to the chisel rake angle is a large negative value, resulting in bit instability, and have a great axial force. And the main twist of the standard twist drill long, cutting width, the point of the chip outflow speed vary greatly, chip possession of space, poor chip removal. People are always looking for ways to shorten the twist drill and reduce the main cutting edge. Although the group drill using more advanced grinding method, but still can not achieve the desired results, and sharpening complex, unfavorable promotion.