Replaceable wear components for percussion tools

Abstract

A piston actuated drilling tool includes a casing and a guide sleeve disposed within the casing in proximity to the top end of the casing. A piston is slidably disposed within the casing for reciprocating movement therein. The piston has a nose end arranged to reciprocate within the guide sleeve, wherein a first wear area of the tool occurs between the piston nose end and the guide sleeve. A replaceable wear bushing assembly is located within the guide sleeve at the first wear area. The replaceable wear bushing assembly can include either a static wear bushing or a sliding wear bushing.

What is claimed is: 
     
         1 . A piston actuated drilling tool comprising:
 a casing having opposed top and bottom ends and an inner surface;   a guide sleeve disposed within the casing in proximity to the top end of the casing, the guide sleeve having an inner surface and an outer surface, the outer surface of the guide sleeve contacting the inner surface of the casing;   a piston slidably disposed within the casing for reciprocating movement therein, the piston having a nose end arranged to reciprocate within the guide sleeve, wherein a first wear area of the tool occurs between the piston nose end and the guide sleeve; and   a replaceable wear bushing assembly located within the guide sleeve at the first wear area.   
     
     
         2 . The drilling tool of  claim 1 , wherein the wear bushing assembly includes a static wear bushing, the nose end of the piston reciprocating within the static bushing. 
     
     
         3 . The drilling tool of  claim 2 , wherein the static wear bushing is a solid piece. 
     
     
         4 . The drilling tool of  claim 2 , wherein the static wear bushing is a split ring. 
     
     
         5 . The drilling tool of  claim 2 , wherein the static wear bushing is a polymer, ferrous, or non-ferrous material. 
     
     
         6 . The drilling tool of  claim 2 , wherein the wear bushing assembly includes a static gland seal disposed between an outer surface of the static wear bushing and the inner surface of the guide sleeve. 
     
     
         7 . The drilling tool of  claim 6 , wherein the gland seal is made of a flexible material such as polymer, elastomer, rubber or ferrous or non-ferrous metals. 
     
     
         8 . The drilling tool of  claim 1 , wherein the inner and outer surfaces of the wear bushing are coated or heat treated. 
     
     
         9 . The drilling tool of  claim 1 , wherein the wear bushing assembly includes a sliding wear bushing arranged to move within the guide sleeve, the nose end of the piston reciprocating within the sliding wear bushing. 
     
     
         10 . The drilling tool of  claim 9 , wherein the position of the sliding wear bushing within the guide sleeve can be inverted to change the sliding wear bushing to a static bushing. 
     
     
         11 . The drilling tool of  claim 9 , wherein the inner and outer surfaces of the sliding wear bushing are coated or heat treated. 
     
     
         12 . The drilling tool of  claim 9 , wherein the wear bushing assembly includes a gland seal located at one end of the sliding wear bushing and a spring mechanism located at another end of the sliding wear bushing, both the sliding gland seal and the spring mechanism being disposed between an outer surface of the sliding wear bushing and the inner surface of the guide sleeve. 
     
     
         13 . The drilling tool of  claim 12 , wherein the gland seal includes a pair of legs. 
     
     
         14 . The drilling tool of  claim 12 , wherein the gland seal is made of a flexible material such as polymer, elastomer, rubber or ferrous or non-ferrous metals. 
     
     
         15 . The drilling tool of  claim 9 , wherein the wear bushing assembly includes a split ring located at one end of the sliding wear bushing, the split ring being disposed between an outer surface of the sliding wear bushing and the inner surface of the guide sleeve. 
     
     
         16 . The drilling tool of  claim 15 , further comprising a spacer ring positioned between the split ring and a shoulder of the sliding bushing, the spacer ring being arranged as a retention ring to keep the sliding wear bushing in a static position. 
     
     
         17 . The drilling tool of  claim 16 , wherein the spacer ring and split ring are made of polymer, elastomer, rubber or ferrous or non-ferrous metals. 
     
     
         18 . The drilling tool of  claim 1 , wherein a second wear area of the tool occurs between the inner surface of casing and the outer surface of the piston, the outer surface of the piston including at least one groove and a piston ring provided in the at least one groove and arranged to protect the piston from wear in the second wear area. 
     
     
         19 . The drilling tool of  claim 18 , wherein the at least one piston ring has overlapping ends. 
     
     
         20 . A piston actuated drilling tool comprising:
 a casing having opposed top and bottom ends and an inner surface;   a guide sleeve disposed within the casing in proximity to the top end of the casing, the guide sleeve having an inner surface and an outer surface;   a piston slidably disposed within the casing for reciprocating movement therein, the piston having a nose end arranged to reciprocate within the guide sleeve, wherein a first wear area of the tool occurs between the piston nose end and the guide sleeve;   a sliding wear bushing arranged to move within the guide sleeve;   a gland seal located at one end of the sliding wear bushing; and   a spring mechanism located at another end of the sliding wear bushing, both the sliding gland seal and the spring mechanism being disposed between an outer surface of the sliding wear bushing and the inner surface of the guide sleeve