Dolly for rockbolt

A rock bolt comprising:

• an elongate rod having a central bore and being externally threaded, the rod having a first or distal end and a second or proximal end;
• a drill bit mounted on the distal end for drilling a bore in strata such as rock or the like wherein the sides of the drill bit taper outwardly towards the cutting end of the drill at an angle of from about 1 to 10°, preferably about 5°;
• an expansion shell mounted about the exterior of the rod adjacent the drill bit, the shell defining at least one longitudinal slot to allow the shell to expand and contract;
• a stop for maintaining the expansion shell in close proximity to the drill bit and limiting the movement of the expansion shell towards the proximal end of the rock bolt;
• wherein the exterior of the shell is contoured to define a series of ridges or the like and wherein the widest part of the shell is wider than the drill bit and wherein the interior of the shell is wider than the exterior of the elongate rod to allow the rod to rotate relative to the shell and wherein the shell is free to rotate relative to the drill bit, and is tapered inwardly towards the proximal end;
• a nut threadably engaged on the rod at the proximal end of the rod, such that rotation of the nut relative to the rod translates the nut along the rod;
• an engagement means for rotating the elongate rod fixed on or defined at a proximal end of the rock bolt, and being fixed to the rod such that rotation of the engagement means causes rotation of the elongate rod;
• the arrangement being such that as the rock bolt is installed in strata, in a first mode both the nut and the elongate rod may be rotated together at the same angular velocity such that the nut does not translate along the rod and the drill bit forms a bore in the strata and the shell tends to drag along the bore wall when thrust forward during drilling and remains largely clear of the spinning rod and drill bit and when drilling ceases, and only the nut is rotated causing movement of the rock bolt out from the bore and causes the drill bit to engage with and expand the shell.

A rock bolt dolly for connecting a self-drilling rock bolt to a rock bolting apparatus and arranged to transfer torque applied to the dolly by the rock bolting apparatus to the rock bolt during installation of the rock bolt, the rock bolt including an externally threaded rod having a proximal end and a distal end defining a drill bit, the dolly defining a coupling means at its proximal end for engagement with the rock bolting apparatus, the dolly further comprising:

• a drive shaft having a central bore for the transmission of fluids for flushing fines and/or cooling during drilling, and defining a proximal end and a distal end, the drive shaft defining an engagement means at the distal end for engagement with a corresponding engagement means located on or defined at the proximal end of the rock bolt;
• a housing mounted around the distal end of the drive shaft and arranged to slide relative to the drive shaft and defining a female engagement means at a distal end, for engaging with a nut or the like threaded onto the proximal end of the rock bolt, the interior of the sleeve and exterior of the drive shaft being configured such that the drive shaft and sleeve rotate together about their central axis, and
• a biasing means for biasing the distal end of the sleeve away from the distal end of the drive shaft;
• the arrangement being such that in a first mode, with the biasing means compressed, the engagement means of the drive shaft is engaged with the corresponding engagement means located on or defined on the proximal end of the rock bolt, and the female engagement means of the sleeve is engaged with the nut or the like threaded onto the proximal end of the rock bolt so that the dolly rotates the rod and nut together such that the nut does not translate along the rod, and in a second mode, with the biasing means expanded, the engagement means of the drive shaft is disengaged from the corresponding engagement means and the female engagement means of the sleeve is engaged with the nut or the like and the dolly rotates the nut only which translates along the externally threaded rod of the rock bolt.

A rock bolt comprising:

• an elongate rod having a central bore and being externally threaded, the rod having a first or distal end and a second or proximal end;
• a drill bit mounted on the distal end for drilling a borehole in strata such as rock or the like wherein the sides of the drill bit taper outwardly towards the cutting end of the drill;
• an expansion shell located adjacent the drill bit,
• a nut threadably engaged on the rod at the proximal end of the rod, such that rotation of the nut relative to the rod translates the nut along the rod;
• and
• an engagement means for rotating the elongate rod fixed on or defined at a proximal end of the rock bolt, and being fixed to the rod such that rotation of the engagement means causes rotation of the elongate rod;
• the arrangement being such that as the rock bolt is installed in strata, in a first mode by engaging both the nut and the engagement means, both the nut and the elongate rod may be rotated together at the same angular velocity such that the nut does not translate along the rod and the drill bit forms a bore in the strata and when drilling ceases, and only the nut is rotated causing movement of the rock bolt out from the bore and causes the drill bit to engage with and expand the expansion shell to anchor the distal end of the rock bolt in the borehole.