Tricone Bit Construction

Abstract

A roller cone drill bit having detachable rotatable arms. The arms are connected at a mounting pad to the bit body. Each arm has its own grease delivery system to provide lubrication to the interface between the arms and rolling elements at an end of each arm. The forward-facing contact surface between the bit body and the arms is at an angle, relative to the central axis of the bit, that is ninety degrees or more.

What is claimed is: 
     
         1 . A bit comprising:
 a body comprising a plurality of grooves, the body connectible to a drill string;   a plurality of bit arms each comprising a plurality of lands corresponding to the plurality of grooves, each of the plurality of bit arms affixed to the body;   a cone rotatably attached to each bit arm, each cone comprising a plurality of teeth;   a fluid delivery system comprising:
 a fluid reservoir disposed within the body; 
 a fluid passage formed within the bit arm; and 
 a ball bearing in communication with the fluid passage, the ball bearing located between the cone and the bit arm; and 
   a connector to connect the plurality of grooves of the body to the plurality of lands of one of the plurality of arms.   
     
     
         2 . The bit of  claim 1  further comprising:
 a drilling fluid passage located within the body portion; and 
 a nozzle for conveying drilling fluid to an exterior of the plurality of bit arms. 
 
     
     
         3 . The bit of  claim 2  wherein the nozzle is directed at the cone of each of the plurality of bit arms. 
     
     
         4 . The bit of  claim 3  comprising three bit arms and three nozzles. 
     
     
         5 . The bit of  claim 1  wherein the fluid delivery system further comprises a pin comprising a central passage located within each bit arm and the body. 
     
     
         6 . The bit of  claim 1  comprising three bit arms. 
     
     
         7 . The bit of  claim 1  wherein the connector comprises a bolt. 
     
     
         8 . The bit of  claim 1  wherein the internal fluid reservoir comprises a spring and a piston to provide fluid pressure to the fluid delivery system. 
     
     
         9 . The bit of  claim 1  wherein the plurality of grooves are straight, curved, or circular. 
     
     
         10 . The bit of  claim 1  further comprising:
 a bore located within each of the bit arms for receiving the connector; and 
 a plurality of threaded holes corresponding to each of the bores in the bit arms for receiving the connector. 
 
     
     
         11 . The bit of  claim 1  wherein the plurality of grooves comprise a front-facing sidewall, wherein an angle between the front-facing wall and a center axis of the body portion is at least 90 degrees. 
     
     
         12 . The bit of  claim 11  wherein the angle is 105 degrees. 
     
     
         13 . The bit of  claim 11  further comprising:
 a drilling fluid passage located within the body portion; and 
 a plurality of nozzles for conveying drilling fluid to the cone section of an exterior of the plurality of bit arms. 
 
     
     
         14 . The bit of  claim 13  comprising three bit arms and three nozzles. 
     
     
         15 . The bit of  claim 1  wherein the fluid reservoir comprises a spring and a piston to provide fluid pressure to the fluid delivery system. 
     
     
         16 . A bit comprising:
 a body comprising a center axis and a mounting pad connectible to a drill string, the mounting pad comprising a plurality of grooves;   a plurality of bit arms comprising a plurality of lands, each of the plurality of bit arms mounted on the body at the mounting pad;   a cone rotatably attached to each bit arm, each cone comprising a plurality of teeth; and   a connector located within each bit arm and the body through the mounting pad.   
     
     
         17 . The bit of  claim 16  wherein the plurality of grooves of the mounting pad comprises a front-facing wall at which one of the plurality of lands of the plurality of bit anus contacts the mounting pad. 
     
     
         18 . The bit of  claim 17  wherein the angle between the center axis and the front-facing wall is 90 degrees or greater. 
     
     
         19 . The bit of  claim 16  further comprising a fluid delivery system, the fluid delivery system comprising:
 a fluid reservoir disposed within the body; 
 a fluid passage formed within the bit arm; 
 a pin within the bit arm and the body and placed through the mounting pad, wherein a hollow passage of the pin is in communication with the fluid reservoir and the fluid passage; and 
 a ball bearing in communication with the fluid passage, the ball bearing located between the cone and the bit arm. 
 
     
     
         20 . The bit of  claim 16  further a drilling fluid passage located within the body portion and a nozzle for conveying drilling fluid to an exterior of the plurality of bit arms. 
     
     
         21 . A method for attaching a plurality of removable but arms to a bit body, the bit body comprising a mounting pad comprising grooves, the plurality of bit arms each comprising lands and a rolling element, the method comprising:
 placing the lands of one of the plurality of bit arms on the mounting pad of the bit body such that the lands and grooves correspond;   placing a connector through the one of the plurality of bit aims and the bit body at the mounting pad;   conveying grease into the removable arm through bit body;   providing a continuous passage through the removable arm proximate ball bearings; and   rotating the rolling elements about the ball bearings to distribute grease from the continuous passage to the ball bearings.   
     
     
         22 . The method of  claim 21  wherein the grease is conveyed to the removable arm from the bit body through a hollow pin. 
     
     
         23 . The method of  claim 21  wherein an angle between a center axis of the bit body and a front-facing wall of the grooves is ninety degrees or more.