すくい面が平面からなるドリルの切削と長ピッチ形切りくず生成機構の解析

Abstract

Main cutting edge configuration of flat rake face drills is geometrically analyzed and compared with the geometry of a conventional twist drill. Applying the cutting model and energy method proposed in previous papers, in which the condition of side-curl of chip is considered, to the case of flat rake face drill, chip formation relating radius of side-curl of the chip and shear angle distribution along the cutting edge, and cutting torque and thrust force can be predicted in both formation processes of a conical-helical chip and a long-pitch helical chip. The differences of torque and thrust force respectively derived from theoretical basis between both chip formation processes are small and the result is experimentally confirmed. The torque and thrust force of the conventional twist drill having a 32° helix angle are almost equal to those of flat rake face drill with rake angle α1=15-20° which is specified in grinding the rake face of the drill.