| 摘要 |
A masonry drill bit includes a cutting insert which is substantially roof-shaped in sideview and has on each side of its“roof”one lip. Each lip includes a leading cutting surface and a trailing free surface, wherein the mutually abutting free surfaces at the roof ridge define a chisel edge. Each free surface is concave in a sub-zone adjacent to the chisel edge in a manner that the radially outer ends of the chisel edge axially protrude at the end face of the insert relative to the in-between center of the chisel edge. Each lip includes at least one recess and to that extent deviates from the substantially roof-shaped geometry. |
