Rock bit with powered gauge cutter

Claim 2

A percussion-type rock bit comprising a solid body with forward working surface and sidewall structure and a rearward, anvil-forming part, hardened cutter inserts in said surface, a chamber extending diagonally into said body from an opening therein adjacent the intersection of said wall structures, a plunger reciprocable in said chamber along a line inclined to the axis of said body, a hardened cutter element on the forward face of said plunger, and a fluid passage extending from said chamber through said anvil-forming part for transmitting to said plunger operating fluid pressures to which sAid anvil-forming part is subjected.

Claim 3

In combination in a percussion drill, a differential fluid pressure motor including a working cylinder, an anvil received in the forward part thereof, a hammer piston reciprocable in said cylinder for beating upon said anvil, a rock bit on the forward part of said anvil having a body with forward and sidewall structures, hardened cutter inserts in said forward wall structure for applying blows from said piston axially to the bottom of a hole being drilled, an exhaust and cleanout fluid duct extending through said anvil and said body, a chamber extending diagonally into said body from an opening adjacent the intersection of said body forward and sidewall structures, a plunger reciprocable in said chamber, a hardened cutter element on the forward face of said plunger, and a fluid passage connecting said chamber rearwardly of said plunger to said working cylinder forwardly of said hammer piston for causing said element to apply a forward and outward blow to the periphery of the hole being drilled for maintaining the gauge of the hole.

Claim 4

In combination in a percussion drill, a differential fluid pressure motor including a working cylinder, an anvil received in the forward part thereof, a hammer piston reciprocable in said cylinder for beating upon said anvil, a rock bit on the forward part of said anvil having a body with forward and sidewall structures, hardened cutter inserts in said forward wall structure for applying blows from said piston axially to the bottom of a hole being drilled, an exhaust and cleanout fluid duct extending through said anvil and said body, a chamber extending diagonally into said body from an opening adjacent the intersection of said body forward and sidewall structures, a plunger reciprocable in said chamber, a hardened cutter element on the forward face of said plunger, and a fluid passage connecting said chamber rearwardly of said plunger to said working cylinder forwardly of said hammer piston for causing said element to apply a forward and outward blow to the periphery of the hole being drilled for maintaining the gauge of the hole.

Claim 5

The combination described in claim 2 in which said motor includes a control rod extending axially through said working cylinder and said piston and into said anvil and connecting with said exhaust duct therein, tubular means in said exhaust duct and normally connecting with said control rod for transmitting motor exhaust through said anvil and bit, said fluid passage under normal working conditions being disconnected from said exhaust duct, said anvil being forwardly movable in said working cylinder when said motor is suspended off bottom to cause disconnection of said tubular means and said control rod and direct connection of said exhaust duct and said working cylinder forward part.

Claim 6

A drilling tool as described in claim 2 further including means retarding the forward motion of said plunger to permit buildup of fluid pressure thereon sufficient to produce a sharp cutting blow of said cutting element.