Percussive drill bit provided with an improved chuck assembly

Abstract

A percussive drill bit provided with an improved chuck assembly for a down-the-hole drill hammer. The bit has a head at its forward end with a shank extending from the head. The shank is screw threaded along its length. A reciprocating chuck is provided as a sleeve with internal screw thread as corresponding to those of the shank. The shank is releasably secured in the chuck with the read end of the shank providing a striking face. An arrangement of external splines on the chuck, and a retaining shoulder at its rear end, provide for the required guided movement of the chuck within a drill hammer wear sleeve.

1 . (canceled) 
     
     
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         3 . (canceled) 
     
     
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         6 . A drill bit and chuck assembly for use with a down-the-hole drill hammer with a reciprocating piston and a wear sleeve or housing, wherein the drill bit and chuck assembly comprises:
 a chuck adapted for insertion in the wear sleeve or housing, so that reciprocal motion of the chuck with respect to the wear sleeve or housing is enabled; and   a drill bit comprising a head with a drilling face, and a shank adapted to be releasably secured in the chuck, which shank comprises a striking face adapted to receive impacts directly from the reciprocating piston.   
     
     
         7 . The drill bit and chuck assembly as claimed in  claim 6 , wherein the shank comprises a screw thread engaged in a corresponding screw thread in the chuck. 
     
     
         8 . The drill bit and chuck assembly as claimed in  claim 6 , wherein the chuck comprises external splines adapted to engage in corresponding splines in the wear sleeve or housing. 
     
     
         9 . The drill bit and chuck assembly as claimed in  claim 6 , wherein the chuck comprises an outwardly or laterally extending shoulder adapted to retain the chuck in the wear sleeve or housing. 
     
     
         10 . The drill bit and chuck assembly as claimed in  claim 6 , wherein the chuck is adapted to be retained in the wear sleeve or housing by an inward lip in the wear sleeve or housing. 
     
     
         11 . The drill bit and chuck assembly as claimed in  claim 6 , wherein the chuck is adapted to be inserted into the wear sleeve or housing from the rear end of the wear sleeve or housing. 
     
     
         12 . The drill bit and chuck assembly as claimed in  claim 6 , wherein the drill bit comprises a foot valve tube and an axial exhaust passage opening through the drilling face. 
     
     
         13 . The drill bit and chuck assembly as claimed in  claim 6 , wherein the drill bit and the chuck are adapted to create axial exhaust paths along the outside of the chuck, along the outside of the bit, through passages in the head and out through the striking face. 
     
     
         14 . The drill bit and chuck assembly as claimed in  claim 6 , wherein the assembly is adapted for use with a reverse circulation hammer and wherein the drill bit is adapted to create axial exhaust paths around the outside of the head and in through a bore in the striking face. 
     
     
         15 . The drill bit and chuck assembly as claimed in  claim 6 , wherein the chuck is adapted to slidably receive a forward end of the piston in order to create a lower chamber with air between the chuck, drill bit and piston, which lower chamber is adapted to lift the piston. 
     
     
         16 . A down-the-hole drill hammer for use with a drill bit, which drill bit comprises a head with a drilling face and a shank with a striking face; wherein the down-the-hole drill hammer comprises:
 a wear sleeve or housing;   a chuck adapted to releasably secure the drill bit, which chuck is inserted in the wear sleeve or housing, so that reciprocal motion of the chuck within the wear sleeve or housing is enabled; and   a reciprocating piston adapted to directly impact the striking face of the drill bit, without impacting the chuck.   
     
     
         17 . The down-the-hole drill hammer as claimed in  claim 16 , wherein the chuck comprises a screw thread adapted to be engaged in a corresponding screw thread in the shank. 
     
     
         18 . The down-the-hole drill hammer as claimed in  claim 16 , wherein the wear sleeve or housing comprises splines engaging in corresponding splines in the shank. 
     
     
         19 . The down-the-hole drill hammer as claimed in  claim 16 , wherein the chuck comprises an outwardly or laterally extending shoulder adapted to retain the chuck in the wear sleeve or housing. 
     
     
         20 . The down-the-hole drill hammer as claimed in  claim 16 , wherein the wear sleeve or housing comprises an inward lip adapted to retain the chuck in the wear sleeve or housing. 
     
     
         21 . The down-the-hole drill hammer as claimed in  claim 16 , wherein the chuck is adapted to be inserted into the wear sleeve or housing from the rear end of the wear sleeve or housing. 
     
     
         22 . The down-the-hole drill hammer as claimed in  claim 16 , wherein the piston is adapted to slidably enter the chuck in order to create a lower chamber with air between the chuck, drill bit and piston, which lower chamber is adapted to lift the piston. 
     
     
         23 . A drill bit for use with a down-the-hole drill hammer with a reciprocating piston, a wear sleeve or housing and a chuck inserted in the wear sleeve or housing, wherein the drill bit comprises a head with a drilling face, and a shank adapted to be releasably secured in the chuck, which shank comprises a striking face adapted to receive impacts directly from the reciprocating piston. 
     
     
         24 . The drill bit as claimed in  claim 23 , wherein the shank comprises a screw thread adapted to be engaged in a corresponding screw thread in the chuck. 
     
     
         25 . The drill bit as claimed in  claim 23 , wherein the drill bit comprises a foot valve tube and an axial exhaust passage opening through the drilling face. 
     
     
         26 . The drill bit as claimed in  claim 23 , wherein the drill bit is adapted to create axial exhaust paths along the outside of the bit, through passages in the head and out through the striking face. 
     
     
         27 . The drill bit as claimed in  claim 23 , wherein the drill bit is adapted for use with a reverse circulation down-the-hole drill hammer and wherein the drill bit is adapted to create axial exhaust paths around the outside of the head and in through a bore in the striking face. 
     
     
         28 . The drill bit as claimed in  claim 23 , wherein the striking face has no openings to passages through the drill bit.