Expansion bail anchor and method

Abstract

An expansion anchor assembly for a mine roof bolt having a tapered plug, expansion leaves, a bail and a removable holding ring configured to hold the expansion anchor assembly in an assembled position is disclosed. The tapered plug is configured to be threaded onto the mine roof bolt and defines plug channels to encourage symmetrical resin flow past the tapered plug. The bail defines a medial opening through which the mine roof bolt extends.

1 . An expansion shell assembly for a mine roof bolt, comprising:
 an expansion shell comprising a pair of leaves, said leaves each having an outer surface for engaging a wall of a mine roof bore hole and an inner surface;   an internally threaded plug received between said inner surfaces of said leaves for threading onto a mine roof bolt, an outer surface of said plug defining a resin groove; and   a bail comprising a pair of legs and a medial member therebetween, each said leg being attached to one said leaf, said medial member defining an aperture through which a mine roof bolt is extendable.   
     
     
         2 . The expansion shell assembly of  claim 1 , wherein said medial member defines a recess aligned with said resin groove of said plug. 
     
     
         3 . The expansion shell assembly of  claim 2 , wherein said medial member is ring-shaped and two opposing portions of said medial member have a reduced radial dimension. 
     
     
         4 . The expansion shell assembly of  claim 2 , wherein said recess comprises a notch in said medial portion. 
     
     
         5 . The expansion shell assembly of  claim 1 , wherein an upper surface of said plug receives said bail medial portion and said plug defines a pair of bail grooves receiving a leg of said bail. 
     
     
         6 . The expansion assembly of  claim 5 , wherein said plug has a sloped upper surface. 
     
     
         7 . A mine roof bolt comprising:
 an elongated rod, said rod having a drive end and a threaded portion; and   an expansion shell assembly as claimed in  claim 1  threaded onto said rod threaded portion.   
     
     
         8 . A mine roof bolt comprising:
 an elongated cable, said cable having a drive end and a distal end;   a threaded member fixed to said cable; and   an expansion shell assembly as claimed in  claim 1  threaded onto said threaded member.   
     
     
         9 . The mine roof bolt of  claim 8 , wherein said threaded member is fixed to said cable at said cable distal end. 
     
     
         10 . The mine roof bolt of  claim 8 , wherein said threaded member is fixed to said cable at a position intermediate said cable drive end and said cable distal end. 
     
     
         11 . In an expansion shell assembly for a mine roof bolt comprising: (i) an expansion shell comprising a pair of leaves, each said leaf having an outer surface for engaging a wall of a mine roof bore hole and an inner surface; (ii) an internally threaded plug received between said leaves for threading onto a mine roof bolt; and (iii) a bail comprising a medial member and a pair of legs extending from opposing sides thereof, the improvement comprising:
 said bail medial member defining a recess and said plug defining a resin groove extending from an upper surface of said plug and being aligned with said bail recess, such that resin is flowable through said bail recess and into said plug groove.   
     
     
         12 . The expansion shell assembly of  claim 11 , wherein said medial member is ring-shaped and two opposing portions of said medial member have a reduced radial dimension. 
     
     
         13 . The expansion shell assembly of  claim 11 , wherein said plug defines a plurality of resin grooves, said resin grooves being aligned with said recess. 
     
     
         14 . The expansion shell assembly of  claim 11 , wherein said bail recess comprises a notch defined in said medial member. 
     
     
         15 . A method of supporting a mine roof comprising:
 (a) inserting a mine roof bolt into a bore hole containing a frangible curable resin cartridge, the mine roof bolt comprising an elongated member having a threaded portion and an expansion shell assembly received on the threaded portion, the expansion shell assembly comprising: (i) an expansion shell comprising a pair of leaves, the leaves having an outer surface and an inner surface; (ii) an internally threaded plug received between the leaves inner surface and threaded on the threaded portion, an outer surface of the plug defining a resin groove; and (iii) a bail comprising a pair of legs extending from a medial member defining an aperture, each leg attached to one of the leaves, wherein the elongated member extends through the aperture;   (b) rupturing the resin cartridge; and   (c) rotating the mine roof bolt such that resin is mixed and flows through the resin groove, and the expansion shell expands and engages the bore hole wall.   
     
     
         16 . The method of  claim 15 , wherein the elongated member comprises a rod. 
     
     
         17 . The method of  claim 15 , wherein the elongated member comprises a multi-strand cable. 
     
     
         18 . The method of  claim 17 , wherein the threaded portion comprises a tube fixed to the cable. 
     
     
         19 . The method of  claim 18 , wherein the tube is fixed to the cable at a position between the drivehead and the end of the cable. 
     
     
         20 . The method of  claim 15 , wherein the bail medial member defines a recess aligned with the plug resin groove so that resin flows through the recess and resin groove.