Table bushing lifting ring

Abstract

A table bushing lifting ring and method for automatically lifting a table bushing during drill bit changing. The method includes providing a drill string and bit sub with a step formed thereon, positioning a table bushing lifting ring on the step, the lifting ring including a plurality of flanges extending beyond the step, lowering the drill string such that the table bushing is received within a deck aperture, providing an automated bit handling mechanism slidable between a standby position during the lowering step where the mechanism is not centered with the drill bit or drill pipe and an engaged position where the bit handling mechanism is centered with the drill bit or pipe, separating the lifting ring from the table bushing as the drill string is lowered, retracting the same, and lifting the table bushing out of the aperture via engagement between the lifting ring flanges and the table bushing.

What is claimed is: 
     
         1 . A table bushing lifting ring arranged for use with a drill string having a bit sub, the lifting ring comprising:
 an annular body having an inner diameter sized to receive the drill string therethrough;   a lower surface configured to engage with a step formed on the bit sub;   an upper surface configured to engage with a lower surface of a table bushing;   and   a plurality of flanges formed at a periphery of the annular body, wherein the flanges extend radially outward beyond a diameter of the step on the bit sub.   
     
     
         2 . The table bushing lifting ring of  claim 1 , wherein the lifting ring is made of a hardened material and/or subjected to case hardening. 
     
     
         3 . The table bushing lifting ring of  claim 1 , wherein the upper surface includes a taper. 
     
     
         4 . The table bushing lifting ring of  claim 1 , wherein the lower surface includes a taper. 
     
     
         5 . The table bushing lifting ring of  claim 1 , wherein both the upper surface and lower surface are tapered. 
     
     
         6 . The table bushing lifting ring of  claim 1 , wherein the lifting ring is configured for use in automated drill bit changing processes. 
     
     
         7 . The table bushing lifting ring of  claim 1 , wherein the lifting ring is replaceable independently of other drill string components. 
     
     
         8 . A drill string assembly comprising:
 a drill string including a drill pipe;   a bit sub connected to the drill pipe, the bit sub having a step formed thereon;   a drill bit threadedly engaged to the bit sub;   a table bushing having a tubular configuration with an opening sized to receive the drill string, the table bushing including a rim at a top end and a lower surface at an opposed end; and   a table bushing lifting ring according to  claim 1  positioned on the step of the bit sub, wherein the table busing lifting ring is configured to lift the table bushing out of a deck aperture when the drill string is retracted.   
     
     
         9 . The drill string assembly of  claim 8 , further comprising a top sub engaged at a top end of the drill pipe. 
     
     
         10 . The drill string assembly of  claim 8 , wherein the lifting ring is configured to centralize the drill string within the deck aperture during drilling operations. 
     
     
         11 . The drill string assembly of  claim 8 , wherein a diameter of the table bushing lifting ring is equal or less than a diameter of the step of the bit sub. 
     
     
         12 . The drill string assembly of  claim 11 , wherein the plurality of flanges of the table bushing ring extend outward beyond the step on the bit sub. 
     
     
         13 . The drill string assembly of  claim 8 , wherein the lower surface of the table bushing lifting ring engages with the step of the bit sub and the upper surface of the table bushing ring engages with the lower surface of the table bushing. 
     
     
         14 . A method for automatically lifting a table bushing during a drill bit changing process, the method comprising:
 providing a drill string having a bit sub with a step formed thereon;   positioning a table bushing lifting ring on the step of the bit sub, the lifting ring including a plurality of flanges extending beyond a diameter of the step;   lowering the drill string such that the table bushing positioned on the drill string is received within a deck aperture;   separating the lifting ring from the table bushing as the drill string continues to be lowered;   retracting the drill string such that the lifting ring reconnects with the table bushing; and   lifting the table bushing out of the deck aperture via engagement between the flanges of the lifting ring and the table bushing.   
     
     
         15 . The method of  claim 14 , further comprising providing and positioning an automated bit handling mechanism on a deck, the automated bit handling mechanism being slidably supported on the deck to move between a standby position during the lowering step where the mechanism is not centered with a drill bit or drill pipe and the deck aperture is not covered by the automated bit handling mechanism and an engaged position where the deck aperture is covered and the automated bit handling mechanism is centered with the drill bit or drill pipe. 
     
     
         16 . The method of  claim 15 , wherein the automated bit handling mechanism is moved to the engaged position after the table bushing is lifted out of the deck aperture. 
     
     
         17 . The method of  claim 16 , further comprising changing the drill bit using the automated bit handling mechanism while the table bushing is lifted out of the deck aperture. 
     
     
         18 . The method of  claim 14 , wherein the step of separating the lifting ring from the table bushing occurs as the bit sub moves downward through the table bushing. 
     
     
         19 . The method of  claim 14 , wherein the step of reconnecting the lifting ring with the table bushing occurs as the bit sub moves upward through the table bushing.