A hybrid bit includes an earth-boring element and a percussion element. The earth-boring element and the percussion element are coaxially arranged, with the earth-boring element surrounding the percussion element. A reciprocating member of the percussion element may oscillate in a manner that enables a bottom end of the reciprocating member to repeatedly protrude from a bottom end of the earth-boring element and to be repeatedly withdrawn. A configuration of the earth-boring element may enable it to drill into and remove some materials from an earth formation, while the percussion element may enable the hybrid bit to drill into and remove difficult-to-drill materials, including abrasive materials and/or materials with high compressive forces, such as chert.

A drilling tool has: a casing pipe in a circular tubular shape; a cylindrical or annular ring bit rotatably fitted to a tip portion of the casing pipe; and a pilot bit inserted into an inner circumference of the ring bit for a striking force to be exerted to toward a tip end side, wherein the ring bit is engaged with and fitted to the casing pipe, projections are formed on an outer circumferential portion of the pilot bit, a recessed trench, and a housing trench, are formed in the inner circumferential part of the ring bit, a torque transmitting surface is formed in the projection, a torque receiving surface capable of abutting the torque transmitting surface is formed in the housing trench, striking force transmitting surfaces are formed in projections, and striking force receiving surfaces capable of abutting the striking force transmitting surfaces are formed in the ring bit.

A drilling tool has: a casing pipe in a circular tubular shape; a cylindrical or annular ring bit rotatably fitted to a tip portion of the casing pipe; and a pilot bit inserted into an inner circumference of the ring bit for a striking force to be exerted to toward a tip end side, wherein the ring bit is engaged with and fitted to the casing pipe, projections are formed on an outer circumferential portion of the pilot bit, a recessed trench, and a housing trench, are formed in the inner circumferential part of the ring bit, a torque transmitting surface is formed in the projection, a torque receiving surface capable of abutting the torque transmitting surface is formed in the housing trench, striking force transmitting surfaces are formed in projections, and striking force receiving surfaces capable of abutting the striking force transmitting surfaces are formed in the ring bit.

A hammering and rotatable drill bit, which is meant for ground and rock drilling includes a hollow shaft having a hole that is adjusted to direct flushing air onto the drilling surface to the front of the drill bit and further from there towards the outer edge of the drill bit. the drill bit includes a drilling part which protrudes from the surface of the drill bit, functions as a drill point and drills the mid-area of the hole to be created wherein the mentioned part is adjusted to prevent the flushing flow from flowing directly through the mentioned hole located inside the shaft onto the drilling surface. The mentioned part is arranged to allow the outlet of the flushing flow in a sideways direction to the grooves belonging to the drilling surface, which grooves lead to the edge of the drill bit, and is arranged to allow the outlet also partly to the front of the drill bit to the drilling surface by adjusting the groove, which leads to the edge of the drill bit, to start from the mentioned part from such a distance (d) from the center line (L) of the drill bit which distance (d) is less than the radius (R) of the hole.

A hammering and rotatable drill bit, which is meant for ground and rock drilling includes a hollow shaft having a hole that is adjusted to direct flushing air onto the drilling surface to the front of the drill bit and further from there towards the outer edge of the drill bit. the drill bit includes a drilling part which protrudes from the surface of the drill bit, functions as a drill point and drills the mid-area of the hole to be created wherein the mentioned part is adjusted to prevent the flushing flow from flowing directly through the mentioned hole located inside the shaft onto the drilling surface. The mentioned part is arranged to allow the outlet of the flushing flow in a sideways direction to the grooves belonging to the drilling surface, which grooves lead to the edge of the drill bit, and is arranged to allow the outlet also partly to the front of the drill bit to the drilling surface by adjusting the groove, which leads to the edge of the drill bit, to start from the mentioned part from such a distance (d) from the center line (L) of the drill bit which distance (d) is less than the radius (R) of the hole.

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 constant velocity joint for downhole power transmission has a first insert mounted in a radially extending drive shaft arm. The first insert engages a second insert mounted along a slot formed in a tubular housing disposed to receive the arm. The material for the two inserts may be different, having different galling properties. An insert may be shaped to have at least a flat surface, a cylindrical surface intersecting the flat surface, and a conical surface intersecting the cylindrical surface. The inserts may extend beyond the cavities in which they are mounted. Opposing cavity walls adjacent the cavity opening may be angled away from one another to permit the insert to flex under a load. The back wall of a cavity and back surface of an insert may be arcuate to permit rotational movement of the insert under a load.

A constant velocity joint for downhole power transmission has a first insert mounted in a radially extending drive shaft arm. The first insert engages a second insert mounted along a slot formed in a tubular housing disposed to receive the arm. The material for the two inserts may be different, having different galling properties. An insert may be shaped to have at least a flat surface, a cylindrical surface intersecting the flat surface, and a conical surface intersecting the cylindrical surface. The inserts may extend beyond the cavities in which they are mounted. Opposing cavity walls adjacent the cavity opening may be angled away from one another to permit the insert to flex under a load. The back wall of a cavity and back surface of an insert may be arcuate to permit rotational movement of the insert under a load.

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.

An apparatus for boring a wellbore, including a bit body having a first end, an inner cavity, and a second end. The first end is connected to a workstring that is configured to deliver a rotational force to the bit body. The inner cavity contains a profile having a first radial cam surface. The second end includes a working face containing a cutting member. The apparatus also includes a pilot bit rotatively connected within the inner cavity. A second radial cam surface is contained on a first end of the pilot bit. The first and second radial cam surfaces are operatively configured to deliver a hammering force. A second end of the pilot bit may include an engaging surface configured to engage a formation surrounding the wellbore. The bit body rotates relative to the pilot bit.