Patent ID: 8157028
Filing Date: 2012-04-17
Classification: B23B,B28D,Y10T

Abstract:
1. A masonry drill bit, comprising: a cutting insert having a substantially roof-shaped configuration in sideview and comprises on each side thereof one lip further comprising a leading cutting surface and a trailing free surface, wherein the free surfaces at a ridge of the roof define a chisel edge, each said free surface being 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, wherein each lip comprises at least one recess and to that extent deviates from the substantially roof-shaped configuration, and two segments of the lip adjoining the at least one recess are configured in axially parallel, and offset to each other in a direction substantially parallel to a longitudinal axis of said drill bit, and in that the lips to this extent deviate further from the roof-like shape, and wherein at least one of the two segments comprises an upper planar surface on said trailing free surface and bounding said concave sub-zone, and said upper planar surface extending away from said at least one recess.