Patent ID: 7896580
Filing Date: 2011-03-01
Classification: E02D,E21D,F16B

Abstract:
1. A self drilling rock bolt comprising first and second ends, a shaft extending between the ends, and an anchoring device, the first end having a drill tip to penetrate rock and the second end being adapted to be connected to a drilling apparatus to allow rotation of, and thrust to, the bolt, the anchoring device being operative to retain the bolt when located in a drilled hole and comprising a mandrel having one or more external surfaces that are inclined to the shaft, the mandrel being mounted to, or integrally formed with, the shaft and at least one expansion element overlaying the mandrel, wherein the at least one expansion element is displaced radially outwardly on a predetermined relative movement between the mandrel and the at least one expansion element, and the bolt is rotated about the shaft axis in a first direction in a drilling operation and is rotated in an opposite second direction to cause the predetermined movement between the mandrel and the at least one expansion element so as to enable the anchoring device to become operative to retain the bolt in a drilled hole.