| 摘要 |
PROBLEM TO BE SOLVED: To provide a drill-bit for rotary-percussive drilling of rock, concrete or the like; which comprises a thin-walled cylindrical drilling body 106 open to the drilling side, a drill-bit base 20 radially extending in effect, and an axially arranged drill-bit shank 101 for fastening the drill-bit. SOLUTION: The drill-bit base 20 has an outer contour in the radial direction, which outer contour follows a curvature having at least one inflection point. Further the drill-bit base is connected to the cylindrical drilling body in the radially outer rising curve segment of its outer contour, wherein the drill-bit whose drill-bit base 20 has an outer contour extending minimum in the radial direction. Further features of the invention are at least one prominence 19 projecting from the inside contour on the inside of the drill-bit base for crushing the material to be drilled, or a cuttings-discharge flute 109, and a variable gradient on the outer contour of the drilling body 106. COPYRIGHT: (C)2006,JPO&NCIPI
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