Down-the hole hammer

Abstract

A down-the-hole hammer is described. It comprises an external cylindrical outer wear sleeve ( 10 ), an inner cylinder ( 9 ) mounted co-axially within the outer wear sleeve ( 10 ), a sliding piston ( 11 ) mounted for reciprocating movement within the inner cylinder ( 9 ) and the outer wear sleeve ( 10 ), to strike a hammer bit ( 40 ) mounted at the lower end of the outer wear sleeve ( 10 ) and an elongate cylindrical air distributor ( 3 ) positioned within the hammer assembly. The lower end of the air distributor ( 3 ) is positioned substantially concentrically within the upper end of the inner cylinder ( 9 ). A shoulder ( 38 ) on the air distributor ( 3 ) engages the underside of a complementary shoulder ( 15 ) on the inner cylinder ( 9 ). The top end of the outer wear sleeve ( 10 ) is screw-threadably engaged with the lower end of an annular air distributor mount ( 2 ), and the top end of the inner cylinder ( 9 ) abuts the lower end of the distributor mount ( 2 ) such that the inner cylinder is rigidly mounted in the drill assembly relative to the outer wear sleeve ( 10 ).

1 . A fluid-operated percussion drill tool, in particular a down-the-hole hammer, comprising an external cylindrical outer wear sleeve ( 10 ), an inner cylinder ( 9 ) mounted co-axially within the outer wear sleeve ( 10 ), a sliding piston ( 11 ) mounted for reciprocating movement within the inner cylinder ( 9 ) and the outer wear sleeve ( 10 ), to strike a hammer bit ( 36 ) mounted at the lower end of the outer wear sleeve ( 10 ), characterised in that the inner cylinder ( 9 ) has an abutment ( 15 ) which in the assembled tool is clamped between a complementary engagement means ( 38 ) and a locking means ( 2 ) such that the inner cylinder ( 9 ) is rigidly mounted and held in the drill tool assembly relative to the outer wear sleeve ( 10 ).  
     
     
         2 . A fluid-operated percussion drill tool as claimed in  claim 1 , characterised in that the top end of the outer wear sleeve ( 10 ) is screw-threadably engaged with the lower end of an annular air distributor mount ( 2 ), the top end of the inner cylinder ( 9 ) abuts the lower end of the distributor mount ( 2 ), a lower end of the air distributor ( 3 ) abuts a shoulder ( 15 ) in the inner cylinder ( 9 ) and is threadably engaged at its upper end with a top locking member ( 1 ). which in its locked position abuts the top of the air distributor mount ( 2 ).  
     
     
         3 . A tool as claimed in  claim 1 , characterised in that there is an elongate cylindrical air distributor ( 3 ) positioned within the hammer assembly and an abutment ( 15 ) on the inner cylinder ( 9 ) engages with a complementary abutment ( 38 ) on the air distributor ( 3 ) and locking means ( 2 ) connected to the outer wear sleeve ( 10 ) are provided to clamp the abutment ( 15 ) between the abutment ( 38 ) on the air distributor ( 3 ), and the locking means is such that the inner cylinder ( 9 ) is rigidly mounted in the drill assembly relative to the outer wear sleeve ( 10 ).  
     
     
         4 . A tool as claimed in  claim 1  or  claim 3 , characterised in that the locking means comprises an annular air distributor mount ( 2 ) the lower end of which is screw-threadably engaged with the top end of the outer wear sleeve ( 10 ).  
     
     
         5 . A tool as claimed in  claim 4  characterised in that the air distributor ( 3 ) is threadably engaged at its upper end with a top locking member ( 1 ) which abuts the top of the air distributor mount ( 2 ).  
     
     
         6 . A tool as claimed in any of the preceding claims characterised in that the inner cylinder ( 9 ) is formed with an inwardly directed abutment which is clamped between the complementary engagement means ( 38 ) and the locking means ( 2 ).  
     
     
         7 . A tool as claimed in any one of the preceding claims characterised in that it comprises a top locking member ( 1 ) screw threadably mounted on an annular air-distributor  3 , which is fitted concentrically through an inner cylinder ( 9 ) and an annular distributor mount ( 2 ), and an annular flange ( 38 ) on the lower end of the air-distributor ( 3 ) abuts the underside of an inwardly-directed abutment ( 15 ) in inner cylinder ( 9 ), and a top end ( 14 ) of the inner cylinder ( 9 ) abuts a lower end of the distributor mount ( 2 ) whereby the inner cylinder ( 9 ) is locked in position.  
     
     
         8 . A tool as claimed in  claim 7 , characterised in that the top end of the inner cylinder ( 9 ) comprises an annular shoulder or flange ( 14 ) which is rigidly held between an annular flange ( 38 ) on the lower end of air-distributor ( 3 ) which abuts an annular shoulder ( 15 ) of the inner cylinder ( 9 ), and the lower end of the distributor mount ( 2 ).  
     
     
         9 . A tool as claimed in any one of  claims 2  to  8 , characterised in that the bottom of the top locking member ( 1 ) has a flat annular rim ( 12 ) which engages a complementary flat shoulder ( 13 ) on the top end of the distributor mount ( 2 ).  
     
     
         10 . A tool as claimed in any one of  claims 2  to  9  characterised in that downward movement of the top locking member  1  against the distributor mount ( 2 ) is controlled by means of a stop ( 51 ) on the air-distributor ( 3 ).  
     
     
         11 . A tool as claimed in  claim 10  characterised in that the stop is provided by means of an annular surface ( 51 ) on the top of the air-distributor  3  which engages with an annular shoulder ( 50 ) on the inner surface of the top locking member ( 1 ).  
     
     
         12 . A tool as claimed in  claim 11 , characterised in that a compression ring is positioned between the annular surface ( 51 ) and the annular shoulder ( 50 ).