A bottomhole assembly includes: a drill bit operable to vibrate when engaged with a formation and rotated; and a suspension sub including: a stator barrel for connection to a pipe string; a traveler barrel for connection to the drill bit; a slip joint longitudinally coupling the traveler barrel to the stator barrel while allowing movement of the traveler barrel between an extended position and a retracted position; a torsional joint connecting the traveler barrel to the stator barrel at and between the positions; and one or more springs disposed between the stator barrel and the traveler barrel. The suspension is tuned relative to the drill bit to: dampen the vibration of the drill bit when the BHA is rotated at a first angular velocity; and resonate the vibration of the drill bit when the BHA is rotated at a second angular velocity, thereby imparting percussive energy to the drill bit.

A bottomhole assembly includes: a drill bit operable to vibrate when engaged with a formation and rotated; and a suspension sub including: a stator barrel for connection to a pipe string; a traveler barrel for connection to the drill bit; a slip joint longitudinally coupling the traveler barrel to the stator barrel while allowing movement of the traveler barrel between an extended position and a retracted position; a torsional joint connecting the traveler barrel to the stator barrel at and between the positions; and one or more springs disposed between the stator barrel and the traveler barrel. The suspension is tuned relative to the drill bit to: dampen the vibration of the drill bit when the BHA is rotated at a first angular velocity; and resonate the vibration of the drill bit when the BHA is rotated at a second angular velocity, thereby imparting percussive energy to the drill bit.

A down the hole drilling assembly has a top end coupled to a drill string and a bottom cutting end. The drilling assembly includes a piston arranged moveably inside a casing with a piston nose positioned at an axially bottom end and a top working chamber at a top end, a bottom working chamber at the bottom end, a driver sub having axially extending driver sub splines on an internal surface, a drill bit having an axially extending central bore including an elongate shank provided with axially extending shank splines on its outer surface for engagement with the driver sub splines to form a spline area, a guide sleeve forming a seal with the piston nose, the guide sleeve having an inner and outer surface, and at least one air passageway extending through the guide sleeve for fluidly connecting the bottom chamber to the spline area to provide lubrication thereto.

A down the hole drilling assembly has a top end coupled to a drill string and a bottom cutting end. The drilling assembly includes a piston arranged moveably inside a casing with a piston nose positioned at an axially bottom end and a top working chamber at a top end, a bottom working chamber at the bottom end, a driver sub having axially extending driver sub splines on an internal surface, a drill bit having an axially extending central bore including an elongate shank provided with axially extending shank splines on its outer surface for engagement with the driver sub splines to form a spline area, a guide sleeve forming a seal with the piston nose, the guide sleeve having an inner and outer surface, and at least one air passageway extending through the guide sleeve for fluidly connecting the bottom chamber to the spline area to provide lubrication thereto.

A flat chisel (1) having a longitudinal axis (7), a shank (2) and a blade-shaped working section (5). The shank (2) has a striking surface (4) perpendicular to the longitudinal axis (7). The working section (5) has a cutting edge (3) that is crosswise to the longitudinal axis (7). The cutting edge (3) is configured so as to be saddle-shaped.

A flat chisel (1) having a longitudinal axis (7), a shank (2) and a blade-shaped working section (5). The shank (2) has a striking surface (4) perpendicular to the longitudinal axis (7). The working section (5) has a cutting edge (3) that is crosswise to the longitudinal axis (7). The cutting edge (3) is configured so as to be saddle-shaped.

A drill bit using track-set depth of cut control elements to provide improved stability is disclosed. A drill bit for drilling a wellbore includes a bit body with a rotational axis extending therethrough. The drill bit further includes a plurality of blades disposed on exterior portions of the bit body. The drill bit includes a first group of track set depth of cut controllers (DOCCs) disposed on exterior portions of a first set of the plurality of blades. The first group of track set DOCCs configured to be placed within a first radial swath of a bit face of the drill bit and configured to provide a first critical depth of cut (CDOC).

A drill bit for a down-the-hole drill hammer is provided that includes a head and a shank extending from the head. The head includes a plurality of non-concentrically or spirally arranged cutting members about its working face. The non-concentric or spiral arrangement of the cutting members in the drill bit and their overlapping cutting paths during rotation of the drill bit reduces the presence of concentric grooves or valleys being cut into the earthen terrain impacted by the bit thereby resulting in more complete cutting coverage.

A drill bit for a down-the-hole drill hammer is provided that includes a head and a shank extending from the head. The head includes a plurality of non-concentrically or spirally arranged cutting members about its working face. The non-concentric or spiral arrangement of the cutting members in the drill bit and their overlapping cutting paths during rotation of the drill bit reduces the presence of concentric grooves or valleys being cut into the earthen terrain impacted by the bit thereby resulting in more complete cutting coverage.

A drill bit button insert of the present invention that is attached to a button inserts mounted in a drill bit and performs a drilling, includes a tip body and an abrasive layer formed of a diamond sintered body harder than the tip body coated at least at the button insert working/cutting surface of the tip body, in which the abrasive layer has at least two high hardness layers and a low hardness layer having a hardness lower than that of the high hardness layer disposed between these high hardness layers from the surface side of the abrasive layer toward the tip body side.