| 摘要 |
PURPOSE:To contrive to improve the boring efficiency and to facilitate the boring by a method wherein a metal-bonded diamond whetstone tip, which is wider than the diameter of a drill main body and has cutting edges made toward a chisel point, is attached. CONSTITUTION:A pair of twist flutes 7, for example, are formed in the longitudinal direction of a drill. A slit 8 is cut at a position symmetrical to the twist flutes 7 at the tip of a main body 1, at the rear end of which a shank to fit to the main spindle of a machine is provided. And, a metal-bonded diamond whetstone tip 9 is fixed to the slit by brazing. Further, the metal-bonded diamond whetstone tip is assembled so as to position its chisel point 4, for example, on the center line of the main body 1. Furthermore, cutting edges 3 and 3 are made toward the chisel point and at the same time chamfering 10 is done to each cutting edge in consideration of stable centering. And, since abrasive grains bite workpiece at all times by the self-generative action or successive development of the cutting edges, continuous boring becomes possible. |
