Apparatus and method for rotary bored drilling

Abstract

Rotary drilling apparatus comprising at least one kelly bar, interlockable with one ore more other kelly bars in end-to-end arrangement such that, in use, a rotational force applied to an uppermost kelly bar is transmitted to each of the kelly bars below it; a tool, for example an auger, having a bore therethrough in which the outer surface of one of said kelly bars can slideably engage; and lifting means for selectively raising and lowering said tool by sliding it over the outer surface of said kelly bars, whereby, in use, said tool is lowered by sliding it over said interlocked kelly bars and attached to a lowermost kelly bar so that a rotational force applied to said lowermost kelly bar is transmitted to the tool, characterised in that at least part of said lifting means is capable or rotation about a longitudinal axis of said kelly bar for synchronous rotation therewith.

1 . Rotary drilling apparatus comprising 
 at least one kelly bar, interlockable with one or more other kelly bars in end-to-end arrangement such that, in use, a rotational force applied to an uppermost kelly bar is transmitted to each of the kelly bars below it;    a tool, for example an auger, having a bore therethrough in which the outer surface of one of said kelly bars can slideably engage; and    lifting means for selectively raising and lowering said tool by sliding it over the outer surface of said kelly bars,    whereby, in use, said tool is lowered by sliding it over said interlocked kelly bars and attached to a lowermost kelly bar so that a rotational force applied to said lowermost kelly bar is transmitted to the tool, characterised in that at least part of said lifting means is capable of rotation about a longitudinal axis of said kelly bar for synchronous rotation therewith.    
     
     
         2 . Rotary drilling apparatus as claimed in  claim 1  wherein said lowermost kelly bar is provided with cutting teeth at its lowermost end.  
     
     
         3 . Rotary drilling apparatus as claimed in  claim 1  or  claim 2  further comprising a tool locking mechanism for locking said tool to said lowermost kelly bar, said tool locking mechanism being engaged by rotation of said lowermost kelly bar relative to said tool in the drilling direction.  
     
     
         4 . Rotary drilling apparatus as claimed in  claim 3  wherein said locking mechanism comprises an inclined keyway on a, said lowermost kelly bar engageable with a keyway on the bore of said tool.  
     
     
         5 . Rotary drilling apparatus as claimed in any of the preceding claims wherein each kelly bar is provided with a longitudinally-extending key.  
     
     
         6 . Rotary drilling apparatus as claimed in any of the preceding claims wherein each kelly bar is provided with a spigot at one end and a complementary socket at the other end so that, in use, the spigot of one kelly bar engages in the socket of another.  
     
     
         7 . Rotary drilling apparatus as claimed in  claim 6  wherein said spigot is at the uppermost end of each kelly bar and said socket is at the lowermost end.  
     
     
         8 . Rotary drilling apparatus as claimed in  claim 6  or  claim 7  wherein the spigot of one kelly bar is, in use, retained in the socket of another kelly bar by a kelly bar locking means which creates a compressive force between mating faces of said kelly bars.  
     
     
         9 . Rotary drilling apparatus as claimed in  claim 8  wherein said kelly bar locking means comprises folding wedges.  
     
     
         10 . Rotary drilling apparatus as claimed in  claim 8  wherein said kelly bar locking means comprises tapered inserts moveable into correspondingly-shaped apertures in the socket of one kelly bar and the spigot of an adjacent kelly bar so as to effect vertical movement of said kelly bars relative to one another and a compressive force therebetween.  
     
     
         11 . Rotary drilling apparatus as claimed in any of claims  5 - 10  wherein each kelly bar is of substantially circular cross-section, apart from said key.  
     
     
         12 . Rotary drilling apparatus as claimed in any of the preceding claims wherein said lifting means comprises hoist ropes lifted by hydraulic lifting means.  
     
     
         13 . Rotary drilling apparatus as claimed in  claim 12  wherein said hydraulic lifting means includes a rotary hydraulic seal.  
     
     
         14 . Rotary drilling apparatus substantially as described herein with reference to any appropriate combination of FIGS. 2-13.  
     
     
         15 . Method of drilling a bore using rotary piling apparatus as claimed in any of the preceding claims.