US 5,628,376 AGranted

Drilling tool bit with a carrier member and cutter members

AssigneeHilti Aktiengesellschaft

InventorWerner Kleine

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Abstract

A drilling bit includes a carrier member (3) shaped, for instance, as a hollow annular crown. In such a crown several cutter members (4) are distributed angularly apart around the circumferentially extending leading end of the carrier member. The cutter members (4) project both radially outwardly and inwardly from the wall thickness of the carrier member. A step (S) is formed in the cutter members spaced from the leading end thereof opposite of the drilling direction. The step (S) is located at the trailing end of a region (K) with a continuous reduction in the radial dimension (R) of the cutter member and the radial dimension is further reduced at the step. Due to the further reduction in the radial dimension at the step (S), the length of the cutter member (4) in the drilling direction, causing friction with the wall surface of the borehole to be drilled, is limited after extended use of the drilling bit, so that the drilling bit retains a higher drilling efficiency even after such extended use.

Claims6

Dependent claims

A drilling bit having a drilling direction and comprising an axially extending carrier member (1, 3) having a leading end facing in the drilling direction and at least one cutter member (2, 4) located at the leading end of said carrier member and having a leading end with a dimension (R) extending transversely of the drilling direction of said carrier member and an axially extending region (K) extending from the leading end with a continuously diminishing transverse dimension in the direction opposite to the drilling direction to a trailing end thereof, said cutter member having an axially extending trailing end region embedded in said carrier member and an axial length (A) between the leading and trailing ends thereof, said at least one cutter member projects in the drilling direction and in the radial direction from the leading end of said carrier member, said at least one cutter member has a radially inwardly directed step (S) at the trailing end of said region (K), said cutter member between said step and the trailing end thereof having a dimension transverse of the drilling direction at least equal to the corresponding transverse dimension of said carrier member in which said cutter member is embedded.

Dependencies are inferred from the claim text.