Early wear detection

Abstract

A drill bit with a bit body having a central bore in communication with a plurality of nozzles for directing drilling fluid; a plurality of cutters defining a cutting face of the bit; and a passageway extending from the central bore toward the cutting face, such that excessive wear of the cutting face opens the passageway to allow the drilling fluid to flow therethrough, thereby reducing a surface pressure of the drilling fluid and indicating excessive wear of the bit. The passageway may extend to adjacent, or within one half inch or three inches of, the cutting face, such that excessive wear opens the passageway to the cutting face. In some cases, the passageway may actually extend through the cutting face with a plug inserted into the passageway at the cutting face to prevent the drilling fluid from exiting the passageway absent wear of the bit.

1 . A drill bit with wear detection feature, the bit comprising:
 a bit body having a central bore in communication with a plurality of nozzles for directing drilling fluid;   a plurality of cutters defining a cutting face of the bit; and   a passageway extending from the central bore toward the cutting face, such that excessive wear of the cutting face opens the passageway to allow the drilling fluid to flow therethrough, thereby reducing a surface pressure of the drilling fluid and indicating excessive wear of the bit.   
     
     
         2 . The bit as set forth in  claim 1 , further including one or more roller cones and wherein the passageway extends into at least one roller cone. 
     
     
         3 . The bit as set forth in  claim 2 , wherein the passageway extends into the roller cone to a cutter on the roller cone. 
     
     
         4 . The bit as set forth in  claim 1 , further including one or more fixed blades and wherein the passageway extends into the blade. 
     
     
         5 . The bit as set forth in  claim 4 , wherein the plurality of cutters are affixed wherein the passageway extends into the blade to at least one of the cutters. 
     
     
         6 . The bit as set forth in  claim 1 , wherein the passageway extends to within three inch of the cutting face, such that excessive wear opens the passageway to the cutting face. 
     
     
         7 . The bit as set forth in  claim 1 , wherein the passageway extends to within one inch of the cutting face, such that excessive wear opens the passageway to the cutting face. 
     
     
         8 . The bit as set forth in  claim 1 , wherein the passageway extends to adjacent the cutting face, such that excessive wear opens the passageway to the cutting face. 
     
     
         9 . The bit as set forth in  claim 1 , wherein the passageway extends through the cutting face with a plug inserted into the passageway at the cutting face to prevent the drilling fluid from exiting the passageway absent wear of the bit. 
     
     
         10 . A drill bit with wear detection feature, the bit comprising:
 a bit body having a central bore in communication with a plurality of nozzles for directing drilling fluid;   one or more legs extending downwardly from the body;   a roller cone rotatably secured to each of the one or more legs;   one or more fixed blades extending downwardly from the body;   a plurality of cutters rigidly secured to each of the one or more blades, wherein the roller cone and cutters define a cutting face of the bit; and   a passageway extending from the central bore toward the cutting face, such that excessive wear of the cutting face opens the passageway to allow the drilling fluid to flow therethrough, thereby reducing a surface pressure of the drilling fluid and indicating excessive wear of the bit.   
     
     
         11 . The bit as set forth in  claim 10 , wherein the passageway extends into the roller cone. 
     
     
         12 . The bit as set forth in  claim 10 , wherein the passageway extends into the roller cone to a cutter on the roller cone. 
     
     
         13 . The bit as set forth in  claim 10 , wherein the passageway extends into the blade. 
     
     
         14 . The bit as set forth in  claim 10 , wherein the passageway extends into the blade to a cutter. 
     
     
         15 . The bit as set forth in  claim 10 , wherein the passageway extends to within three inch of the cutting face, such that excessive wear opens the passageway to the cutting face. 
     
     
         16 . The bit as set forth in  claim 10 , wherein the passageway extends to within one inch of the cutting face, such that excessive wear opens the passageway to the cutting face. 
     
     
         17 . The bit as set forth in  claim 1 , wherein the passageway extends to adjacent the cutting face, such that excessive wear opens the passageway to the cutting face. 
     
     
         18 . The bit as set forth in  claim 1 , wherein the passageway extends through the cutting face with a plug inserted into the passageway at the cutting face to prevent the drilling fluid from exiting the passageway absent wear of the bit. 
     
     
         19 . A drill bit with wear detection feature, the bit comprising:
 a bit body having a central bore in communication with a plurality of nozzles for directing drilling fluid;   cutting structure defining a cutting face of the bit; and   a passageway extending from the central bore to the cutting face; and   a plug in the passageway, at the cutting face, such that excessive wear of the cutting face erodes the plug and opens the passageway to allow the drilling fluid to flow therethrough, thereby reducing a surface pressure of the drilling fluid and indicating excessive wear of the bit.