| 摘要 |
A drill bit (10) for use in rotary hammer drilling machines to drill holes i n rock, masonry and concrete which includes an axially extending shank (12) having a plurality of helical discharge grooves (16, 18) therein and definin g a convex end face (14). A cylindrical projection (20) is centrally disposed on the end face of the shank (12) and defines a pyramid-shaped cutting tip (24) . A plurality of primary cutting members (30), generally rectangular in configuration, are embedded in the shank (12) such that the cutting members (30) are spaced from and extend radially from the cylindrical projection (20 ) so as to define gaps between the cutting members (30) and the projection (20 ). One of the cutting members is laterally adjacent an upper end portion of eac h of the discharge grooves (16, 18). The combination of the cylindrical projection (20) and surrounding primary cutting members (30) pulverize and pressurize drilled material and direct drilled material along the side wall of the cylindrical projection (20) and into the gaps between the projection and the primary cutting members where the material is compressed to assist in th e drilling process and enhance drilling speed and is subsequently directed int o the discharge grooves (16, 18) for removal.
|
