Bit retaining system

Abstract

A retaining system ( 100 ) for a DTH hammer drill bit ( 25 ) having an outer surface with a plurality of stops ( 31 ) at an up-hole end ( 29 ) of the drill bit ( 25 ) the stops projecting radially outward from the outer surface and spaced by respective gaps ( 35 ). The retaining system has a ring ( 102 ) which is configured to pass over the stops ( 31 ) when in a first rotational position relative to the drill bit ( 25 ). However when the ring ( 102 ) is in a second rotational position relative to the drill bit ( 25 ) it prohibits passage of the stops ( 31 ) through the ring ( 102 ).

1 . A retaining system for a DTH hammer drill bit having an outer surface with a plurality of stops at an up-hole end of the drill bit the stops projecting radially outward from the outer surface and spaced by respective gaps, the retaining system comprising: a ring configured to pass over the stops in a first rotational position relative to the drill bit and prohibit passage of the stops through the ring when the ring is in a second rotational position relative to the drill bit. 
     
     
         2 . The retaining system according to  claim 1  wherein the ring has an inner circumferential surface provided with a plurality of circumferentially spaced apart inwardly projection lugs. 
     
     
         3 . The retaining system according to  claim 2  wherein the lugs are arranged so that when the ring is in the second position the lugs are in substantial axial alignment with the stops. 
     
     
         4 . The retaining system according to  claim 2  wherein the lugs are arranged so that when the ring is in the first position the lugs are in substantial axial alignment with the gaps. 
     
     
         5 . The retaining system according to  claim 1  wherein the ring has an inner circumferential surface provided with a plurality circumferentially spaced apart recesses that extend in an axial direction. 
     
     
         6 . The retaining system according to  claim 5  wherein the recesses are arranged so that when the ring is in the second position the recesses are in substantial axial alignment with the gaps. 
     
     
         7 . The retaining system according to  claim 5  wherein the recesses are arranged so that when the ring is in the first position the lugs are in substantial axial alignment with the stops whereby the ring is able to pass over the stops to surround a portion of the drill bit. 
     
     
         8 . The retaining system according to  claim 1  wherein the ring has an inner circumferential surface provided with a plurality of circumferentially spaced apart inwardly projection lugs the lugs being spaced apart by respective axially extending recess, the lugs and recesses arranged so that when the ring is in the first position the recesses are in axial alignment with the stops to enable the ring to pass over the stops and surround a portion of the drill bit and when the ring is moved to the second position the lugs are in substantial axial alignment with the stops to prohibit the drill bit from axially passing out of the ring. 
     
     
         9 . The retaining system according to  claim 1  comprising a detent system capable of holding the ring in the second position. 
     
     
         10 . The retaining system according to  claim 9  wherein the detent system comprises a sleeve locatable over a portion of the drill bit and wherein the sleeve and the ring are provided with complimentary parts capable of interlocking with each other. 
     
     
         11 . The retaining system according to  claim 10  wherein the complementary parts comprise teeth or castellations formed on each of the ring and the sleeve. 
     
     
         12 . The retaining system according to  claim 10  wherein the complementary parts comprise male parts formed on one of the ring and sleeve, and female parts formed on the other of the ring and sleeve. 
     
     
         13 . The retaining system according to  claim 10  wherein the sleeve is provided with an inner circumferential surface which is provided to inhibit substantial relative rotation of the sleeve about the drill bit. 
     
     
         14 . The retaining system according to  claim 13  wherein the circumferential surface of the sleeve is provided with a plurality of projections capable of residing in axially extending grooves formed on the drill bit wherein the projections are dimensioned to prevent passage in a rotational direction over axially extending splines formed on the drill bit which interleave with the grooves. 
     
     
         15 . A bit retaining system for a DTH hammer drill bit having an outer surface with a stop mechanism at an up-hole end of the drill bit, the stop mechanism projecting radially outward from the outer surface, the retaining system comprising: a ring having an inner circumferential surface provided with a plurality of lugs projecting in a radial inward direction the lugs being spaced apart by respective axially extending recess, the lugs arranged to prevent to stop mechanism from passing through the ring. 
     
     
         16 . The retaining system according to  claim 1  wherein the ring is formed as single one piece continuous ring. 
     
     
         17 . The retaining system according to  claim 1  wherein the ring comprises two or more segments which when juxtaposed end to end form the ring. 
     
     
         18 . The retaining system according to  claim 17  comprising a bias mechanism operable to bias the segments toward a common center. 
     
     
         19 . The retaining system according to  claim 18  wherein the bias mechanism comprises one or more: resilient  0 -rings; clips or spring clips. 
     
     
         20 . A retaining system for a DTH hammer drill bit having an outer surface with a stop mechanism at an up-hole end of the drill bit the stop mechanism projecting radially outward from the outer surface, the retaining system comprising: a ring formed of two or more segments; the ring having an inner circumferential surface provided with a plurality of circumferentially spaced apart inwardly projection lugs the lugs being spaced apart by respective axially extending recess, the lugs and recesses arranged so that the lugs project inwardly of the stop mechanism to prevent the stop mechanism from passing axially through the ring. 
     
     
         21 . The retaining system according to  claim 20  wherein the recesses are arranged to form channels opposite the outer surface of the drill bit to enable fluid flow between the ring the and the bit. 
     
     
         22 . The retaining system according to  claim 20  comprising a detent system capable of holding the ring in a fixed rotational position relative to the drill bit. 
     
     
         23 . The retaining system according to  claim 22  wherein the detent system comprises a sleeve locatable over a portion of the drill bit and wherein the sleeve and the ring are provided with complementary parts arranged to interlock when in axial alignment. 
     
     
         24 . The retaining system according to  claim 23  wherein the complementary parts comprise teeth or castellations formed on each of the ring and the sleeve. 
     
     
         25 . The retaining system according to  claim 20  wherein when the drill bit is formed with plurality of axially extending and interleaved grooves and splines between the stop mechanism and a bit face of the drill bit, the detent system is arranged so that when ring in a fixed rotational position relative to the drill bit the recess on the ring are in radial alignment with the grooves on the drill bit.