TWIST DRILL REAMER FOR THE HIGH SPEED MACHINING OF THE DIFFICULT-TO-CUT MATERIALS

摘要

A twist drill reamer for high speed machining of difficult-to-machine materials is provided to improve processing efficiency in boring and extend tool life and improve precision in boring and obtain good surface roughness. In a twist drill reamer for high speed machining of difficult-to-machine materials, a pair main cutting edges(E1) are formed at the front end without having margin and two pair of second cutting edges(E2) and third cutting edges(E3) are installed at the outer circumference and the margin(M2) of the second cutting edge is in the range of 0.4~0.6mm and the margin(M3) of the third cutting edge is in the range of 0.6~0.7mm. The tip-end external diameter of the second cutting edge and the third cutting edge has wider length of 0.02~0.06mm than the-end external diameter of the main cutting edge. The width(W) between a central line(O1) passing through the center of the twist drill reamer and the main cutting edge is 0.078~0.082D. The margin angle has 9~11 degree and the tip angle has 135~145 degree and chisel blade width(T1) has 0.025~0.035D. The chisel blade angle has 120~130 degree and thinning cutting edge angle has 150~160 degree and web width(T2) has 0.29~0.31D.