Down-the-hole drill hammer

Abstract

A down-the-hole drill hammer comprises a sleeve ( 46 ) which defines a cylinder in which a piston is reciprocable. A plurality of axially extending ribs are formed on the outer surface or the sleeve, and conduits are formed in at least one of the fibs for conveying compressed air or another drive fluid to ports in the sleeve, to operate the piston. This arrangement makes it possible to increase the effective diameter of the hammer as a percentage of the bit diameter, which is particularly useful in relatively small drill hammers.

1 - 12 . (cancelled).  
     
     
         13 . A down-the-hole drill hammer comprising: 
 a sleeve defining a cylinder and defining a plurality of axially extending ribs on the outer surface thereof, the ribs defining passages between them for the flushing of drilled material;    a piston reciprocable within the cylinder and arranged to operate a bit percussively;    a shank reciprocable axially relative to the sleeve and having a first end within the sleeve engagable by the piston, and a second end extending beyond the sleeve and adapted to receive a bit; and    at least one conduit formed in said at least one rib of the sleeve for conveying a drive    fluid to one or more ports defined in the sleeve to operate the piston.    
     
     
         14 . A down-the-hole drill hammer according to  claim 13  wherein said at least one rib in the sleeve is formed integrally with the sleeve, with said at least one conduit comprising a bore drilled in the sleeve.  
     
     
         15 . A down-the-hole drill hammer according to  claim 14  wherein the sleeve and the ribs thereof are formed by machining or extrusion.  
     
     
         16 . A down-the-hole drill hammer according to  claim 13  wherein the sleeve comprises an inner sleeve defining the cylinder within which the hammer is reciprocable, and an outer sleeve defining said at least one axially extending rib on the outer surface thereof, with said at least one conduit being defined between the inner and outer sleeves.  
     
     
         17 . A down-the-hole drill hammer according to  claim 16  wherein the inner sleeve is formed from tubing or pipe, with the outer sleeve defining hollow axially extending ribs and being fitted about the inner sleeve.  
     
     
         18 . A down-the-hole drill hammer according to  claim 17  wherein the ribs are defined by ridges or corrugations in the outer sleeve.  
     
     
         19 . A down-the-hole drill hammer according to  claim 18  wherein the outer sleeve defining the ribs comprises a relatively thick-walled cylinder having axially extending slots formed in its inner surface adjacent the ribs, the inner sleeve fitting snugly within the outer sleeve to close off the slots, thereby to define the conduits.  
     
     
         20 . A down-the-hole drill hammer according to  claim 19  wherein the slots are formed by machining or extrusion.  
     
     
         21 . A down-the-hole drill hammer according to  claim 13  wherein the second end of the shank is threaded to permit a bit to be screwed into position thereon.  
     
     
         22 . A down-the-hole drill hammer according to  claim 20  wherein the portion of the shank extending beyond the sleeve has a diameter greater than the internal diameter of the sleeve.  
     
     
         23 . A down-the-hole drill hammer according to  claim 22  wherein the portion of the shank extending beyond the sleeve has a diameter substantially equal to the maximum outer diameter of the sleeve.  
     
     
         24 . A down-the-hole drill hammer according to  claim 13  wherein one or more of the conduits in the sleeve are designed to carry a flow of fluid to the bottom of the hole being drilled, said one or more conduits extending to the lower end of the wearsleeve and being ported to the exterior of the sleeve.