Modular drill bit

Apparatus for use in a drill bit comprising the combination of:

• a leg;
• a cone rotatably mounted on the leg;
• a roller thrust bearing disposed between the cone and the leg, the leg and the cone forming an interface therebetween terminating at an outer periphery of the cone and the roller thrust bearing being located within the interface adjacent the outer periphery of the cone;
• and
• a second roller thrust bearing located within the interface and inside of the first-mentioned roller thrust bearing.

Apparatus for use in a drill bit comprising the combination of:

• a leg;
• a cone rotatably mounted on the leg;
• a roller thrust bearing disposed between the cone and the leg, the leg and the cone forming an interface therebetween terminating at an outer located within the interface adjacent the outer periphery of the cone;
• and
• a main bearing disposed between the cone and the leg, and wherein the roller thrust bearing is disposed outside of the main bearing.

Apparatus for use in a drill bit comprising the combination of:

• a leg;
• a cone rotatably mounted on the leg;
• and
• a roller thrust bearing disposed between the cone and the leg, the leg and the cone forming an interface therebetween terminating at an outer periphery of the cone and the roller thrust bearing being located within the interface adjacent the outer periphery of the cone, the roller thrust bearing including a generally ring-shaped bearing retainer having a plurality of radial slots therein and a plurality of rollers disposed within the radial slots.

Apparatus for use in a drill bit comprising the combination of:

• a leg terminating in a spindle, the spindle having a central axis and having a circular bearing race concentrically disposed relative to the central axis and having a back wall lying in a plane generally normal to the central axis;
• a cone rotatably mounted on the spindle and having a central axis of rotation generally coincident with the central axis of the spindle and a bearing race concentrically disposed relative to the central axis of the cone and having a wall lying in a plane generally normal to the central axis of the cone, the wall of the bearing race of the cone being spaced apart from and generally parallel to the back wall of the bearing race of the spindle;
• and
• a thrust bearing mounted within the bearing race of the spindle and the bearing race of the cone and extending between the back wall of the bearing race of the spindle and the wall of the bearing race of the cone, the thrust bearing includes a ring-shaped retainer having an array of radial slots therein and a plurality of cylindrical rollers disposed in the radial slots.

Apparatus for use in a drill bit comprising the combination of:

• a leg terminating in a spindle, the spindle having a central axis and having a circular bearing race concentrically disposed relative to the central axis and having a back wall lying in a plane generally normally to the central axis;
• a cone rotatably mounted on the spindle and having a central axis of rotation generally coincident with the central axis of the spindle and a bearing race concentrically disposed relative to the central axis of the cone and having a wall lying in a plane generally normal to the central axis of the cone, the wall of the bearing race of the cone being spaced apart from and generally parallel to the back wall of the bearing race of the spindle;
• a thrust bearing mounted within the bearing race of the spindle and the bearing race of the cone and extending between the back wall of the bearing race of the spindle and the wall of the bearing race of the cone, the thrust bearing having an outer diameter and an inner diameter;
• and
• a main roller having disposed between the spindle and the cone to facilitate rotation of the cone on the spindle, the main roller bearing being disposed adjacent the inner diameter of the thrust bearing.

Apparatus for use in a drill bit comprising the combination of:

• a leg;
• a cone rotatably mounted on the leg and forming an interface therewith;
• at least one bearing disposed between the leg and the cone between an inner portion and a radial outer portion of the interface;
• and
• means within the leg for recirculating lubricating oil from the radial outer portion of the interface of the inner portion of the interface for supply to a region encompassing the at least one bearing.

Apparatus for use in a drill bit comprising the combination of:

• a leg;
• a cone rotatably mounted on the leg;
• and
• a seal disposed between the leg and the cone, the seal engaging both the leg and the cone and being free to slide relative to both the leg and the cone when the cone rotates on the leg, the seal having an outer surface having a plurality of concentric ribs thereon to facilitate sliding of the seal relative to the leg and the cone.

Apparatus for use in a drill bit comprising the combination of:

• an elongated leg having a cone-mounting end thereof with an outer edge;
• a cone rotatably mounted on the cone-mounting end of the leg, the cone having an outer rim at a base portion thereof of greatest diameter adjacent the outer edge of the cone-mounting end of the leg, a generally conical surface on one side of the outer rim, and an extended portion thereof on a side of the outer rim opposite the conical surface which extends over and protects the outer edge of the cone-mounting end of the leg;
• a generally ring-shaped nut secured to the extended portion of the cone, the nut extending over and having an inside diameter smaller than the outer edge of the cone-mounting end of the leg to prevent removal of the cone from the leg;
• a washer seal disposed between and sealing the space between the nut and the leg, the washer seal being generally ring-shaped and slidably disposed adjacent both the nut and the leg so as to be slidable relative to both the nut and the leg when the cone and the nut are rotated relative to the leg;
• and
• a pre-seal disposed between the cone and the leg on the opposite side of the washer seal from the nut, the pre-seal being slidable relative to both the nut and the leg when the cone and the nut are rotated relative to the leg.

Apparatus for use in a drill bit comprising the combination of:

• a leg;
• a cone rotatably mounted on the leg and having a portion of greatest diameter at an outer rim at a base thereof and a generally conical portion on one side of the outer rim;
• a nut secured to the cone at a portion of the cone on an opposite side of the outer rim from the generally conical portion, the nut extending over the leg and acting to secure the cone on the leg;
• a washer seal disposed between and sealing the space between the nut and the leg, the washer seal being slidably disposed against both the nut and the leg so as to be slidable relative to both the nut and the leg when the cone and the nut are rotated relative to the leg;
• and
• a pre-seal slidably disposed against both the cone and the leg, on an opposite side of the washer seal from the nut, the pre-seal being slidable relative to both the cone and the leg when the cone is rotated relative to the leg.

Apparatus for use in a drill bit comprising the combination of:

• a leg;
• a cone rotatably mounted on the leg and having a portion of greatest diameter at an outer rim at a base thereof and a generally conical portion on one side of the outer rim;
• a nut secured to the cone at a portion of the gone on an opposite side of the outer rim from the generally conical portion, the nut extending over the leg and acting to secure the cone on the leg;
• and
• a washer seal disposed between and sealing the space between the nut and the leg, the washer seal being generally ring-shaped and having a plurality of concentric ribs on an outer surface thereof.

A method of mounting a cone on the spindle of a leg in a drill bit, comprising the steps of:

• providing a leg having a spindle with a threaded portion;
• providing a cone;
• providing a lock nut;
• temporarily securing the lock nut at the inside of the cone while rotating the spindle relative to the cone to screw the lock nut onto the threaded portion of the spindle and secure the cone against removal from the spindle;
• releasing the lock nut at the inside of the cone so that the cone is thereafter free to rotate relative to the spindle;
• providing a ring-nut;
• and
• screwing the ring-nut onto an extended outer portion of the cone simultaneously with screwing of the lock nut onto the threaded portion of the spindle.