Patent attributes
A masonry or rock drilling tool suitable for use with a rotary hammer has a drilling head (4, 104) at a forward end of the tool. A forwardly extending cutting plate (6, 106) is fitted or formed on the drilling head (4, 104). First and second opposing axially extending channels (36, 38, 136, 138) are formed on the circumferential periphery of the drilling head. The tool has a clamping shank (2, 102) at a rearward end of the tool suitable for fitment within a tool holder of a rotary hammer. An intermediate helical conveying portion (10, 110) extends between the drilling head and the clamping shank. The intermediate helical conveying portion has at least four helically extending flutes (14a–d, 114a–d) separated by corresponding helically extending webs (12a–d, 112a–d). The first of the axially extending channels extend axially rearwardly from a forward facing face of the drilling head into two of the four flutes. The second of the axially extending channels extend axially rearwardly from the forward facing face of the drilling head into the other two of the four flutes. Conveying properties of the tool are substantially enhanced by having each axially extending channel leading into two of the four flutes.
