Securing arrangement for reamers in raise boring

Abstract

A safety arrangement which pertains to drill bits for reamer drilling and which is intended to prevent the drill bit from falling freely down the hole in the event of a breakage in an element that connects the drill bit with an overlying rotatable carrier element, the element forming part of a drill string that carries the drill bit, wherein the element includes a longitudinal hole that extends internally along at least a part of the length of the element, and the hole has disposed therein a safety device which functions to capture the element and therewith also the drill bit should the element break, the capture being achieved by virtue of the safety device being connected to a threaded part of the overlying element and also to a part of the element located at a distance from the threaded part of the element.

1 . A safety arrangement pertaining to drill bits for reamer drilling that is intended to prevent the drill bit ( 1 ) from falling freely down the hole in the event of a breakage in an element ( 3 ) that connects the drill bit ( 1 ) with an overlying rotatable carrier element, said element forming part of a drill string that carries the drill bit ( 1 ), characterised in that the element ( 3 ) includes a longitudinal hole ( 6 ) that extends internally along at least a part of the length of said element ( 3 ), and wherein the hole has disposed therein a safety device ( 5 ) which functions to capture the element and therewith also the drill bit ( 1 ) should the element ( 3 ) break, said capture being achieved by virtue of the safety device ( 5 ) being connected to a threaded part ( 4 ) of the overlying element ( 3 ) and also to a part of said element ( 3 ) located at a distance from said threaded part ( 4 ) of the element.  
   
   
       2 . A safety arrangement according to  claim 1 , characterised in that the safety device ( 5 ) has the form of a safety rod ( 5 ) which has a respective transverse member ( 9 ,  10 ) at each of its ends, wherein said transverse members ( 9 ,  10 ) have a length that is greater than the diameter of the hole ( 6 ) in the element ( 3 ) and are accommodated in respective widened portions ( 7 ,  8 ;  7 ,  8 ′) of the hole ( 6 ) in the proximity of respective ends of the safety rod ( 5 ).  
   
   
       3 . A safety arrangement according to  claim 2 , characterised in that at least one of the widened portions ( 8 ′) of the hole ( 6 ) in the element ( 3 ) has a given extension axially, so that the element ( 3 ) can move slightly in an axial direction in the event of a breakage.  
   
   
       4 . A safety arrangement according to  claim 2 , characterised in that the transverse element ( 9 ,  10 ) is a flange that projects outwardly from the safety rod.  
   
   
       5 . A safety arrangement according to  claim 1 , characterised in that the element ( 3 ) is the stinger ( 3 ) that is connected directly to the drill bit ( 1 ).  
   
   
       6 . A safety arrangement according to  claim 1 , characterised in that said element is a stabiliser included in the drill string.  
   
   
       7 . A safety arrangement according to  claim 1 , characterised in that said element is a connecting drill pipe included in the drill string.  
   
   
       8 . A safety arrangement according to  claim 3 , characterised in that the transverse element ( 9 ,  10 ) is a flange that projects outwardly from the safety rod.  
   
   
       9 . A safety arrangement according to  claim 2 , characterised in that the element ( 3 ) is the stinger ( 3 ) that is connected directly to the drill bit ( 1 ).  
   
   
       10 . A safety arrangement according to  claim 3 , characterised in that the element ( 3 ) is the stinger ( 3 ) that is connected directly to the drill bit ( 1 ).  
   
   
       11 . A safety arrangement according to  claim 4 , characterised in that the element ( 3 ) is the stinger ( 3 ) that is connected directly to the drill bit ( 1 ).  
   
   
       12 . A safety arrangement according to  claim 8 , characterised in that the element ( 3 ) is the stinger ( 3 ) that is connected directly to the drill bit ( 1 ).