LONG DRILL FORMED OF SUPER-HARD MATERIAL FOR DEEP HOLE BORING

摘要

PROBLEM TO BE SOLVED: To provide a long-life long drill formed of a super-hard material for deep hole boring capable of performing the deep hole boring stably even to a hard material difficult to be bored.;SOLUTION: (a) The length L₁ of a back taper section 30 in the axial direction is within a range of 3D-6D relative to a drill diameter D, and the thickness W₁ of a web at the front end of the drill is within a range of 0.30D-0.45D. (b) The thickness W₂ of the web in a parallel section 32 is within a range of 0.25D-0.40D. (c) The length L₃ in the axial direction including that of a reverse taper section 34 up to a groove cut-up section 18e is within a range of 1.5D-3.5D, and the maximum thickness W₃ of the web in the reverse taper section 34 is within a range of 0.30D-0.45D. (d) The helix angle of a chip discharging groove 18 is within a range of 10-23°. The long drill 10 with such a constitution can suppress the occurrence of the early breakage of a tool, abnormal noise, or vibration, enables stable cutting, and can elongate a life of the tool remarkably.;COPYRIGHT: (C)2008,JPO&INPIT