| 摘要 |
PURPOSE:To provide a boring tool for hard-to-cut material such as FRP with high performance and long life, by affixing a hard sintered material of composite structure to the tip of a drill, removing the surface course on the rack face and by forming a positive-angled rake face from said sintered material. CONSTITUTION:A hard sintered material 2 of composite structure, wherein a hard sintering of diamond, for ex., is sandwiched in between plates of metal or sintered carbides 5, 5' is affixed to the tip of a drill 1 in such a way that the main flanks 6, 6' on both sides are point symmetrical about the center of the drill shank. Then those plate portions which mate with the rake face on this composite sintering 2, the lip of cutting edge, and the peripheral cutting edge are removed, and the portions shall be constituted from the hard sintering 4. Both the rake angle alpha in the radial direction of drill and the rake angle thetain the axial direction are formed in positive angles. This will enhance the cutting performance and anti-abrasiveness. |
