Drill bit for percussive drilling

Abstract

A drill bit for use in percussive drilling includes a body having a front face, at least one face button on the front face, and a plurality of gauge buttons. Each of the buttons has a working face. At least a portion of at least one gauge button working face has a curvature which deviates further from being flat by comparison to a curvature of any curved portion of at least one face button working face, so that the portion of at least one gauge button working face projects further than the portion of at least one face button working face.

1 . A drill bit for use in percussive drilling, the drill bit comprising;
 a body having a front face;   at least one face button on the front face; and   a plurality of gauge buttons, each of the face and plurality of gauge buttons having a working face, wherein at least a portion of at least one gauge button working face has a curvature which deviates further from being flat by comparison to a curvature of any curved portion of the at least one face button working face, so that said portion of at the least one gauge button working face projects further than said portion of at least one face button working face.   
     
     
         2 . The drill bit of  claim 1 , wherein at least a portion of the working face of each of the face and plurality of gauge buttons is curved. 
     
     
         3 . The drill bit of  claim 2 , wherein the entirety of the working face of each of the face and plurality of gauge buttons is curved. 
     
     
         4 . The drill bit of  claim 3 , wherein the curvature of the working face of at least one gauge button deviates further from being flat than the curvature of the working face of at least one face button. 
     
     
         5 . The drill bit of  claim 3 , wherein each gauge button working face projects further from its associated body portion than the or each face button working face. 
     
     
         6 . The drill bit of  claim 3 , wherein the working face of at least one gauge button is substantially hemispherical. 
     
     
         7 . The drill bit of  claim 3 , wherein the working face of at least one face button is substantially shaped like a segment of a hemisphere. 
     
     
         8 . The drill bit of  claim 1 , wherein each of the face and plurality of gauge buttons includes a substantially cylindrical body. 
     
     
         9 . The drill bit of  claim 1 , further comprising a plurality of face buttons. 
     
     
         10 . The drill bit of  claim 1 , further comprising a central axis, and each face button is offset with respect to the central axis. 
     
     
         11 . The drill bit of  claim 1 , wherein the working face of at least one face button is substantially flat.