Reverse circulation hammer with modular bit

Abstract

Embodiments provide apparatuses and methods for excavation and drilling, particularly reverse circulation hammers and bits. Reverse circulation hammers and bits manufactured in accordance with various embodiments may help to prevent fatigue and breaking of the bit during a drilling operation, may prevent clogging of return holes, may provide higher efficiency drilling operations, and may provide modular bit designs that may be interchanged to suit a particular drilling operation.

1 . A reverse circulation hammer and drill bit comprising:
 a drive sub configured to receive rotational torque;   a back head coupled to the drive sub and configured to receive rotational torque therefrom;   a porting barrel coupled to the back head and configured to receive rotational torque therefrom;   a modular bit coupled to the porting barrel and configured to receive rotational torque therefrom; and   a pneumatic reciprocating piston configured to transmit impact force to the modular bit via a modular bit shaft at a hammer impact area; wherein the hammer strike zone is does not receive rotational torque directly form the drive sub, back head, or porting barrel.   
     
     
         2 . The reverse circulation hammer and drill bit of  claim 1 , wherein the porting barrel comprises a generally cylindrical shape having a wall and an inner bore, and wherein the pneumatic reciprocating piston is adapted to fit within the inner bore of the porting barrel. 
     
     
         3 . The reverse circulation hammer and drill bit of  claim 2 , wherein rotational torque is transmitted via the wall and impact force is transmitted within the inner bore via the pneumatic reciprocating piston. 
     
     
         4 . The reverse circulation hammer and drill bit of  claim 1 , wherein the hammer impact area is free of keys, splines, and hex drive features. 
     
     
         5 . The reverse circulation hammer and drill bit of  claim 1 , wherein the piston is free of keys, splines, and hex drive features. 
     
     
         6 . The reverse circulation hammer and drill bit of  claim 1 , wherein the drive sub, back head, and porting barrel comprise an external rotational drive mechanism. 
     
     
         7 . The reverse circulation hammer and drill bit of  claim 6 , wherein the external rotation drive mechanism comprises one or more key drive, hex drive, or external spline systems. 
     
     
         8 . The reverse circulation hammer and drill bit of  claim 6 , wherein the external rotational drive system comprises a cylinder having an external surface, and internal surface, and an inner bore, and wherein the one or more key drive, hex drive, or external spline systems is located on the outer surface of the cylinder. 
     
     
         9 . The reverse circulation hammer and drill bit of  claim 1 , wherein the modular bit and the porting barrel are coupled at a coupling area, and wherein the coupling area is less than about five inches tall. 
     
     
         10 . The reverse circulation hammer and drill bit of  claim 1 , wherein the drill bit has a mass of about 250 pounds or less. 
     
     
         11 . The reverse circulation hammer and drill bit of  claim 1 , further comprising an annular check valve. 
     
     
         12 . A modular drill bit for use with a reverse circulation hammer, wherein the drill bit comprises an outer drive ring and a bit face plate, and wherein the drill bit further comprises a plurality of vertical return holes configured to allow the passage of air, water, and/or debris through the bit face and up through the reverse circulation hammer. 
     
     
         13 . The modular drill bit of  claim 12 , wherein the vertical return holes comprise substantially no bends. 
     
     
         14 . The modular drill bit of  claim 12 , wherein the bit face plate comprises a front face and back surface, and wherein the vertical return holes have a smaller diameter at the front face of the bit face plate than on the back face of the bit face plate. 
     
     
         15 . The modular drill bit of  claim 12 , wherein the drill bit comprises from about 3 to about 6 vertical return holes. 
     
     
         16 . The modular drill bit of  claim 12 , wherein the vertical return holes have a draft angle configured to facilitate the passage of debris. 
     
     
         17 . The modular drill bit of  claim 12 , wherein the outer drive ring is configured to receive rotational torque. 
     
     
         18 . The modular drill bit of  claim 12 , wherein the modular drill bit further comprises a shank and a striker. 
     
     
         19 . The modular drill bit of  claim 18 , wherein the outer drive ring, bit face plate, shank, and striker are replaceable. 
     
     
         20 . The modular drill bit of  claim 12 , wherein the outer drive ring comprises a key drive system, a hex drive system, or a spline drive system. 
     
     
         21 . The modular drill bit system of  claim 12 , wherein the outer drive ring is configured to be removed and replaced with a modular component adapter. 
     
     
         22 . The modular drill bit system of  claim 21 , wherein the modular component adapter comprises an overburden ring, a ring bit system, an underreamer, or an adapter for a larger or smaller bit.