A weight-on-bit self-adjusting drill bit includes a reaming bit, a WOB adjusting element, a transmission mechanism and a pilot bit and a pulsating impact generating mechanism; the pulsating impact generating mechanism includes a centralizing element, a driving element, a rotating element and a throttling element which are placed and connected successively, the centralizing element, the driving element and the rotating element are connected successively, the throttling element is in clearance fit with the rotating element, both of the centralizing element and the throttling element are respectively provided with a flow-through passage for the drilling fluid to flow through, the driving element drives the rotating element to rotate, the rotating element rotates relative to the flow-through passage on the throttling element.

A cutter head arrangement comprising a cutter head portion including a cutter head side wall to define a chamber (or cavity) surrounded by the cutter head side wall. A substantially circular rim portion extends from (a distal end of) the cutter head side wall, the rim portion defining a working, contact face of the cutter head portion. A recessed wall portion extends away from the rim portion inwardly into the chanber so as to be surrounded by the cutter head side wall, with the rim portion and/or the recessed wall portion being fitter with a plurality of cutter elemenets, to enable the cutter head portion to blind bore a pilot hole in use. The recessed wall portion that extends away from the rim portion inwardly into the chamber is a substantially conical body so as to define a conical recess.

A cutter head arrangement comprising a cutter head portion including a cutter head side wall to define a chamber (or cavity) surrounded by the cutter head side wall. A substantially circular rim portion extends from (a distal end of) the cutter head side wall, the rim portion defining a working, contact face of the cutter head portion. A recessed wall portion extends away from the rim portion inwardly into the chanber so as to be surrounded by the cutter head side wall, with the rim portion and/or the recessed wall portion being fitter with a plurality of cutter elemenets, to enable the cutter head portion to blind bore a pilot hole in use. The recessed wall portion that extends away from the rim portion inwardly into the chamber is a substantially conical body so as to define a conical recess.

A downhole tool, comprising: a mandrel having first and second opposing ends and an outer mounting surface, the first end comprising a male threaded portion; a tool component mountable on the mounting surface by sliding said tool component onto the mounting surface from the first end of the mandrel; and a load sleeve defining a torque shoulder, wherein the load sleeve is mountable on the mandrel and securable adjacent the male threaded portion of the first end of the mandrel such that the torque shoulder and the male threaded portion define a pin connector to facilitate connection with a box connector of a separate component.

A downhole tool, comprising: a mandrel having first and second opposing ends and an outer mounting surface, the first end comprising a male threaded portion; a tool component mountable on the mounting surface by sliding said tool component onto the mounting surface from the first end of the mandrel; and a load sleeve defining a torque shoulder, wherein the load sleeve is mountable on the mandrel and securable adjacent the male threaded portion of the first end of the mandrel such that the torque shoulder and the male threaded portion define a pin connector to facilitate connection with a box connector of a separate component.

An earth-boring drill bit is described, the bit having a bit body having a central longitudinal axis that defines an axial center of the bit body and configured at its upper extent for connection into a drill string; at least one primary fixed blade extending downwardly from the bit body and inwardly toward, but not proximate to, the central axis of the drill bit; at least one secondary fixed blade extending radially outward from proximate the central axis of the drill bit; a plurality of fixed cutting elements secured to the primary and secondary fixed blades; at least one bit leg secured to the bit body; and a rolling cutter mounted for rotation on the bit leg; wherein the fixed cutting elements on at least one fixed blade extend from a center of the bit outward toward a gage region of the bit but do not include a gage cutting region, and wherein at least one roller-cone cutter portion extends from substantially the drill bit's gage region inwardly toward the center of the bit, an apex of the roller-cone cutter being proximate to the terminal end of the at least one secondary fixed blade, but does not extend to the center of the bit.

An earth-boring drill bit is described, the bit having a bit body having a central longitudinal axis that defines an axial center of the bit body and configured at its upper extent for connection into a drill string; at least one primary fixed blade extending downwardly from the bit body and inwardly toward, but not proximate to, the central axis of the drill bit; at least one secondary fixed blade extending radially outward from proximate the central axis of the drill bit; a plurality of fixed cutting elements secured to the primary and secondary fixed blades; at least one bit leg secured to the bit body; and a rolling cutter mounted for rotation on the bit leg; wherein the fixed cutting elements on at least one fixed blade extend from a center of the bit outward toward a gage region of the bit but do not include a gage cutting region, and wherein at least one roller-cone cutter portion extends from substantially the drill bit's gage region inwardly toward the center of the bit, an apex of the roller-cone cutter being proximate to the terminal end of the at least one secondary fixed blade, but does not extend to the center of the bit.

A cutting assembly and method for drilling an underground borehole. The cutting assembly includes front and rear cutting heads of different diameters mounted on a shaft. An air passage defined through the cutting assembly may be placed in fluid communication with a pressurized remote air source and with a bore of a casing extending rearwardly from the cutting assembly. Pressurized air flows through the air passage and entrains cuttings produced by the front and rear cutting heads. A housing extends rearwardly from the larger diameter rear cutting head and an auger provided within the housing aids in directing cuttings into the casing. The auger rotates independently of the rest of the cutting assembly and may be configured to further reduce the size of the cuttings. A collar on the housing seals the borehole cut by the rear cutting assembly and aids in preventing frac-out.

A cutting assembly and method for drilling an underground borehole. The cutting assembly includes front and rear cutting heads of different diameters mounted on a shaft. An air passage defined through the cutting assembly may be placed in fluid communication with a pressurized remote air source and with a bore of a casing extending rearwardly from the cutting assembly. Pressurized air flows through the air passage and entrains cuttings produced by the front and rear cutting heads. A housing extends rearwardly from the larger diameter rear cutting head and an auger provided within the housing aids in directing cuttings into the casing. The auger rotates independently of the rest of the cutting assembly and may be configured to further reduce the size of the cuttings. A collar on the housing seals the borehole cut by the rear cutting assembly and aids in preventing frac-out.

The present application relates to a weight-on-bit self-adjusting drill bit, namely a pulsed jet type weight-on-bit self-adjusting drill bit, comprising a reaming bit, a WOB adjusting element, a transmission mechanism and a pilot bit and a pulsating impact generating mechanism; the pulsating impact generating mechanism comprises a centralizing element, a driving element, a rotating element and a throttling element which are placed and connected successively, the centralizing element, the driving element and the rotating element are connected successively, the throttling element is in clearance fit with the rotating element, both of the centralizing element and the throttling element are respectively provided with a flow-through passage for the drilling fluid to flow through, the driving element drives the rotating element to rotate, the rotating element rotates relative to the flow-through passage on the throttling element. Compared with the prior art, the present application can realize the rotary percussion drilling of the pilot bit, reduce the chip hold down effect of the pilot bit and the reaming bit, and realize the automatic and reasonable distribution of the weight on bit, thus to protect the bit, improve the bit service life and rate of penetration, and improve the drilling effect.