Percussion drill bit with V-shaped splines

Abstract

A drill bit is disclosed for use in a percussion drilling apparatus of the type for boring into the earth. Embodiments of the drill bit comprise an elongate body with a first end, a second end, and a longitudinal surface extending between the first and second ends. Embodiments further comprise a plurality of splines on the longitudinal surface of the drill bit, with at least one of the plurality of splines comprising an apex, a root, and a planar surface between the apex and root. In preferred embodiments, the planar surface is oriented at an angle between 10 and 45 degrees to a plane extending from a center of the drill bit to a midpoint of the apex.

1 . A drill bit for use in a percussion drilling apparatus of the type for boring into the earth, said drill bit comprising: 
 an elongate body with a first end, a second end, a central axis, and a longitudinal surface disposed about said axis and extending between said first and said second ends; and    a plurality of splines on said longitudinal surface of said drill bit, wherein at least one of said plurality of splines comprises a base portion, an apex, a root, and a generally planar surface between said apex and said root, wherein a first plane parallel to said generally planar surface is oriented at an angle between 10 and 45 degrees to a second plane extending from said axis to a midpoint of said apex and wherein the base portion is wider than the apex.    
   
   
       2 . The drill bit of  claim 1  wherein said plurality of splines comprises a plurality of roots and each root comprises a radiused portion with a root radius that connects said planar surface from a first spline of said plurality of splines to a second planar surface from a second spline of said plurality of splines.  
   
   
       3 . The drill bit of  claim 2  further comprising a diameter inscribing said roots of said plurality of splines, wherein the ratio of said diameter to said root radius is less than 50.  
   
   
       4 . The drill bit of  claim 1  wherein said angle is between 20 and 35 degrees.  
   
   
       5 . The drill bit of  claim 1  wherein said root does not comprise a substantially flat surface.  
   
   
       6 . The drill bit of  claim 1  wherein the root comprises a curved surface that intersects a pair of planar surfaces adjacent to the root.  
   
   
       7 . The drill bit of  claim 1 , wherein: 
 said plurality of splines extend a distance L along said longitudinal surface;    said elongate body has a minor diameter d; and    a ratio of L/d is less than 0.7.    
   
   
       8 . The drill bit of  claim 7  wherein the ratio of L/D is between 0.60 and 0.40.  
   
   
       9 . The drill bit of  claim 1  wherein the root comprises a curved surface that intersects a pair of planar surfaces adjacent to the root.  
   
   
       10 . A drill bit for use in a percussion drilling apparatus of the type for boring into the earth, said drill bit comprising: 
 an elongate body with a central axis;    a plurality of splines disposed on said elongate body, said splines disposed parallel to said central axis, wherein at least one of said plurality of splines comprises a base portion and an apex, wherein the base portion is wider than the apex and the apex is disposed between a first planar surface and a second planar surface;    wherein a first plane parallel to said first planar surface is oriented at a first angle between 10 degrees and 45 degrees to a second plane extending from said central axis to a midpoint of said apex; and    wherein a third plane parallel to said second planar surface is oriented at a second angle between 10 degrees and 45 degrees to said second plane.    
   
   
       11 . The drill bit of  claim 10 , wherein the first angle is between 20 and 35 degrees.  
   
   
       12 . The drill bit of  claim 10 , wherein the second angle is between 20 and 35 degrees.  
   
   
       13 . The drill bit of  claim 10 , further comprising a root on either side of said apex, wherein said root comprises a root radius and does not comprise a flat surface.  
   
   
       14 . The drill bit of  claim 13  further comprising a diameter inscribing said roots of said plurality of splines, wherein the ratio of said diameter to said root radius is less than 50.  
   
   
       15 . The drill bit of  claim 13  wherein the root comprises a curved surface, wherein the curved surface intersects a first planar surface adjacent to the root and the curved surface intersects a second planar surface adjacent to the root.  
   
   
       16 . A drill bit for use in a percussion drilling apparatus of the type for boring into the earth, said drill bit comprising: 
 an elongate body;    a plurality of splines disposed on said elongate body, wherein at least one of said plurality of splines comprises a first and second surface angled relative to one another and configured to form an angle therebetween of between 20 and 90 degrees.    
   
   
       17 . The drill bit of  claim 16  wherein the angle is between 40 and 70 degrees.  
   
   
       18 . The drill bit of  claim 16 , further comprising a root adjacent to the first angled surface, wherein said root does not comprise a flat surface.  
   
   
       19 . A percussion drilling assembly comprising: 
 a top sub;    a driver sub with a first plurality of V-shaped splines, wherein each spline comprises a pair of angled surfaces configured to form an angle of between 20 and 90 degrees;    a case disposed between said top sub and said driver sub;    a piston disposed within said case; and    a bit with a second plurality of V-shaped splines engaged with said first plurality of V-shaped splines.    
   
   
       20 . The percussion drilling assembly of  claim 19  wherein the angle is between 40 and 70 degrees.  
   
   
       21 . The percussion drilling assembly of  claim 19  wherein the driver sub further comprises a root between a first angled surface from a first spline and a second angled surface from a second spline, wherein the root does not comprise a flat surface.  
   
   
       22 . The percussion drilling assembly of  claim 19  wherein the root comprises a curved surface that intersects the first angled surface and the second angled surface.  
   
   
       23 . A method of drilling into the earth comprising the steps of: 
 providing a drill bit with an elongate body and a first plurality of splines on said elongate body;    providing a drive collar with a second plurality of splines that slideably engage said first plurality of splines;    providing a piston;    impacting said piston against said drill bit;    impacting said drill bit against the earth; and    rotating said drive collar and said drill bit, wherein at least one of said first plurality of splines comprises a base portion, an apex, a root, and a planar surface between said apex and said root, wherein the base portion is wider than the apex and a first plane parallel to said planar surface is oriented at an angle between 10 degrees and 45 degrees to a second plane extending from a center of said drill bit to a midpoint of said apex.    
   
   
       24 . The method of  claim 23  wherein the angle is between 20 and 35 degrees.