Rock bolt

Abstract

A rock bolt has a rectangular blade, which can pierce and shred a flexible housing, extending from cross-shaped mixing formations at one end of an elongate rod.

1 . A rock bolt which includes an elongate shank with a leading end and a trailing end, a shear device fixed to the trailing end, the shank including a frusto-conical section at the leading end and a shredding and mixing structure which extends from the frusto-conical section. 
     
     
         2 . A rock bolt according to  claim 1  wherein the frusto-conical section terminates in a substantially planar surface which is transverse to a longitudinal axis of the shank and the shredding and mixing structure projects from the substantially planar surface. 
     
     
         3 . A rock bolt according to  claim 1  wherein the threading and mixing structure includes a blade which is centrally positioned on the planar surface. 
     
     
         4 . A rock bolt according to  claim 3  wherein the blade, in outline, is square or rectangular and each corner of the blade, remote from the planar surface, forms a right angle. 
     
     
         5 . A rock bolt according to  claim 3  wherein the shredding and mixing structure includes mixing members which project outwardly from and transversely to a base of the blade. 
     
     
         6 . A rock bolt according to  claim 5  wherein the mixing members have a length in an axial direction of the shank taken from the substantially planar surface which is less than 14% of the length of the shank, taken in the axial direction, from the substantially planar surface. 
     
     
         7 . A rock bolt according to  claim 1  wherein at least part of the shank is coated with a release medium. 
     
     
         8 . A rock bolt according to  claim 1  wherein the shank is made from round bar and the frusto-conical section and the shredding and mixing structure are forged integrally with the shank. 
     
     
         9 . A rock bolt according to  claim 2  wherein the threading and mixing structure includes a blade which is centrally positioned on the planar surface. 
     
     
         10 . A rock bolt according to  claim 9  wherein the blade, in outline, is square or rectangular and each corner of the blade, remote from the planar surface, forms a right angle. 
     
     
         11 . A rock bolt according to  claim 4  wherein the shredding and mixing structure includes mixing members which project outwardly from and transversely to a base of the blade. 
     
     
         12 . A rock bolt according to  claim 11  wherein the mixing members have a length in an axial direction of the shank taken from the substantially planar surface which is less than 14% of the length of the shank, taken in the axial direction, from the substantially planar surface.