| 摘要 |
PCT No. PCT/JP89/00804 Sec. 371 Date Aug. 14, 1990 Sec. 102(e) Date Aug. 14, 1990 PCT Filed Aug. 4, 1989 PCT Pub. No. WO90/14189 PCT Pub. Date Nov. 29, 1990.A high speed burnishing drill having drilling edges and reaming edges provided at the forward end of a cylindrical drilling body. The drilling edges are inclined diametrically from the center of the forward end to the axially rearward direction, while the outermost peripheral wall of the drilling edges are on a reduced-diameter portion of the maximum external diameter of the drill body. The reaming edges extend from the plane intersecting the drilling edges radially from a position inward of the outermost peripheral of the drilling edges, outwards, so as to incline axially in the forward direction with a second cutting angle. A reduced diameter portion extends axially backward from the outermost peripheral wall of the drilling edges. An enlarged-diameter guide face extends axially from a slope behind the corresponding drilling edge in the rotational direction, and the forwardmost end of the enlarged guide face is located axially behind the corresponding reaming edge. |
