Patent attributes
A self drilling rock bolt incorporating a shaft and an anchoring device. A first end of the bolt has a drill tip to penetrate rock and a second end is adapted to be connected to a drilling apparatus to allow rotation of, and thrust to, the bolt. A circulation passage is provided to allow fluid to be passed to the drill tip and in one form a central passage is formed in the shaft to form part of this circulation passage. The anchoring device is operative to retain the bolt when located in a drilled hole and comprises a mandrel having one or more inclined external surface mounted to, or integrally formed with, the shaft and at least one expansion element overlaying the mandrel. The expansion element(s) is displaced radially outwardly on a predetermined relative movement between the mandrel and the element.
