Drill bit

Abstract

A drill bit is made from a shank, lid and blades. Junk slots with higher resistance to flow are provided to force drilling fluid between cutters on adjacent blades to improve cleaning. Blades are canted back, and openings at a high angle are provided to further enhance cleaning. The use of a lid facilitates high angle openings.

1 . A drill bit, comprising: 
 a drill bit body having a cutting end and a central flow passage;    plural blades extending out from the cutting end of the drill bit body;    cutters in each one of the plural blades;    nozzles in the drill bit body passing through the cutting end, and providing a flow path between the central flow passage and the cutting end;    plural junk slots in the drill bit body, each blade of the plural blades separating adjacent junk slots;    the junk slots alternating in pairs around the cutting end, each pair of junk slots including a junk slot with a higher resistance to fluid flow and a junk slot with a lower resistance to fluid flow, with an intervening blade between the pair of junk slots, such that, in operation, the junk slot of each pair of junk slots with higher resistance to fluid flow forces drilling fluid from the junk slot with higher resistance into the junk slot with lower resistance, the drilling fluid being forced across the intervening blade and between the cutters of the intervening blade.    
   
   
       2 . The drill bit of  claim 1  in which the blades alternate between primary blades and secondary blades, and the primary blades are the intervening blades.  
   
   
       3 . The drill bit of  claim 2  in which each junk slot with higher resistance incorporates a restriction in the junk slot.  
   
   
       4 . The drill bit of  claim 3  in which the restrictions comprise an extension of a blade.  
   
   
       5 . The drill bit of  claim 4  in which each restriction comprises an extension of a secondary blade.  
   
   
       6 . The drill bit of  claim 5  in which each restriction of a pair of junk slots sweeps circumferentially under the intervening blade.  
   
   
       7 . The drill bit of  claim 1  in which each blade is canted backward.  
   
   
       8 . The drill bit of  claim 1  in which the drill bit body has a rotational axis, and the nozzles are oriented at an angle greater than 15° to the rotational axis and directed to force drilling fluid between the blades.  
   
   
       9 . The drill bit of  claim 8  in which the drill bit body includes a shank, and the cutting end of the drill bit body is formed of a lid welded to the shank.  
   
   
       10 . The drill bit of  claim 9  in which the blades are welded into slots in the lid.  
   
   
       11 - 23 . (canceled)  
   
   
       24 . A drill bit, comprising: 
 a drill bit body having a cutting end, a central flow passage and a rotational axis;    plural blades extending out from the cutting end of the drill bit body, the blades being made of material having a first heat conductivity;    cutters in each one of the plural blades;    nozzles in the drill bit body passing through the cutting end, and providing a flow path between the central flow passage and the cutting end, the nozzles being directed to force drilling fluid between the blades;    heat conducting conduits in each blade, each heat conducting conduit terminating in heat conducting proximity to a cutter on the respective blade, the heat conducting conduits leading into the blade away from the cutters, and the heat conducting conduits being made of a material having a second heat conductivity, the second heat conductivity being higher than the first heat conductivity; and    plural junk slots in the drill bit body, each blade of the plural blades separating adjacent junk slots.    
   
   
       25 . A method of making a drill bit, the method comprising the steps of: 
 separately machining a shank and lid for the shank;    forming slots in the lid for blades;    welding the lid to the shank; and    welding blades into the slots in the lid.