The present invention relates to a drill bit assembly for fluid-operated percussion drill tools comprising a percussion bit having a head portion and a bit retaining portion. Engagement means are provided on the head portion engageable with complementary engagement means on a drive ring whereby rotational drive from the drive ring may be transmitted to the percussion bit. The assembly also comprises bit retaining means adapted for engagement with the bit retaining portion of the percussion bit to retain the percussion bit in the drill bit assembly. Connection means on the drive ring are adapted for connecting the drive ring to a drive means of the fluid-operated percussion drill tool. According to a first aspect, the drive ring comprises a plurality of separable part-annular drive dog segments, wherein the bit retaining means are provided on at least two of the drive dog segments. According to a second aspect the head portion of the bit comprises a main body and a plurality of bit inserts engaged therewith, and wherein the engagement means is provided by the bit inserts.

The present invention relates to a drill bit assembly for fluid-operated percussion drill tools comprising a percussion bit having a head portion and a bit retaining portion. Engagement means are provided on the head portion engageable with complementary engagement means on a drive ring whereby rotational drive from the drive ring may be transmitted to the percussion bit. The assembly also comprises bit retaining means adapted for engagement with the bit retaining portion of the percussion bit to retain the percussion bit in the drill bit assembly. Connection means on the drive ring are adapted for connecting the drive ring to a drive means of the fluid-operated percussion drill tool. According to a first aspect, the drive ring comprises a plurality of separable part-annular drive dog segments, wherein the bit retaining means are provided on at least two of the drive dog segments. According to a second aspect the head portion of the bit comprises a main body and a plurality of bit inserts engaged therewith, and wherein the engagement means is provided by the bit inserts.

The present invention relates to a drill bit assembly for fluid-operated percussion drill tools comprising a percussion bit having a head portion and a bit retaining portion. Engagement means are provided on the head portion engageable with complementary engagement means on a drive ring whereby rotational drive from the drive ring may be transmitted to the percussion bit. The assembly also comprises bit retaining means adapted for engagement with the bit retaining portion of the percussion bit to retain the percussion bit in the drill bit assembly. Connection means on the drive ring are adapted for connecting the drive ring to a drive means of the fluid-operated percussion drill tool. According to a first aspect, the drive ring comprises a plurality of separable part-annular drive dog segments, wherein the bit retaining means are provided on at least two of the drive dog segments. According to a second aspect the head portion of the bit comprises a main body and a plurality of bit inserts engaged therewith, and wherein the engagement means is provided by the bit inserts.

Systems for forming or extending a tunnel or shaft within geologic material may include a ram accelerator assembly for accelerating one or more projectiles into geologic material to weaken a region of the geologic material. The projectile(s) pre-condition the geologic material, such as by forming one or more holes in a central region of the material or to define a perimeter of the region to be displaced. A cutting tool or subsequent projectile impacts may then be used to remove the weakened material. The voids formed by the first projectile(s) cause compressive forces from subsequent impacts or cutting operations to be converted to tension forces that more efficiently break geologic material, which may fall into the voids created by the first projectile(s). The voids created by the projectile impacts may also control the material that is removed and the shape of a resulting section of the tunnel or shaft.

A drill assembly for percussive drilling, comprising a drill bit and a percussion device. The drill assembly further includes a hollow cylindrical foot valve partially received within a first central flushing channel thereof and extending therefrom in the uphole direction, such that the foot valve is also partially received within a central recess of an impact piston of the percussion device, at least when the impact piston is in a lowermost position of its reciprocation cycle, and such that the foot valve is no longer received within the central recess, at least when the impact piston is in an uppermost position of its reciprocation cycle. The foot valve includes an internal stiffener extending radially inwardly from at least two circumferential positions of an inner surface of the foot valve.

A drill assembly for percussive drilling, comprising a drill bit and a percussion device. The drill assembly further includes a hollow cylindrical foot valve partially received within a first central flushing channel thereof and extending therefrom in the uphole direction, such that the foot valve is also partially received within a central recess of an impact piston of the percussion device, at least when the impact piston is in a lowermost position of its reciprocation cycle, and such that the foot valve is no longer received within the central recess, at least when the impact piston is in an uppermost position of its reciprocation cycle. The foot valve includes an internal stiffener extending radially inwardly from at least two circumferential positions of an inner surface of the foot valve.

Disclosed is a drillable adaptive turbine guide shoe, including an adaptive booster component and a power casing shoe component; the adaptive booster component includes a supercharging hollow shaft, a supercharging shell, a disc spring group, a shunt head, a jet oscillator and a semi-cylindrical ring, the supercharging hollow shaft is slidably connected to the supercharging shell, one end of the supercharging hollow shaft is a liquid inlet end and the other end is closed, a cavity is formed between the supercharging hollow shaft and the supercharging shell, and the disc spring group is built in the cavity, the jet oscillator and the semi-cylindrical ring are mounted on the inner wall of the supercharging shell, and one side of the jet oscillator and the semi-cylindrical ring abuts against the shunt head, the shunt head is sleeved on the outer wall of the supercharging hollow shaft; this disclosure solves the problem that the casing cannot be effectively run when the wellbore has sand bridges or wellbore necking.

The present invention relates to a hydraulic down-the-hole hammer. The hammer comprises an elongate shaft and a piston having a central bore therethrough, the piston slidably mounted for reciprocal movement on the shaft and arranged to impact a percussion bit. Forward and rear drive chambers for the piston are disposed between the piston and the shaft and the forward chamber is separated from the rear chamber by an annular shoulder formed internally of the piston bore. The hammer also comprises a control valve to control reciprocation of the piston, wherein the control valve is arranged within the central bore of the piston. The hammer may be a disposable water hammer in which the piston is an outermost component of the hammer.

The present invention relates to a hydraulic down-the-hole hammer. The hammer comprises an elongate shaft and a piston having a central bore therethrough, the piston slidably mounted for reciprocal movement on the shaft and arranged to impact a percussion bit. Forward and rear drive chambers for the piston are disposed between the piston and the shaft and the forward chamber is separated from the rear chamber by an annular shoulder formed internally of the piston bore. The hammer also comprises a control valve to control reciprocation of the piston, wherein the control valve is arranged within the central bore of the piston. The hammer may be a disposable water hammer in which the piston is an outermost component of the hammer.

An arrangement and a method for installing a casing in a borehole are described. The arrangement includes a casing, a boring pipe, which is adapted within the casing, and the boring pipe includes flow channels for compressed air and a flushing medium. The flushing medium flow channel is arranged to lead the flushing medium to the bottom of the borehole. The arrangement also includes a percussion hammer, which includes a compressed air operated percussion piston adapted in a cylinder of the percussion hammer, as well as hole drilling means for drilling a hole for the casing. The flushing medium flow channel is adapted to bypass the percussion piston or which flushing medium flow channel is adapted to pass through the percussion piston, and in which arrangement the drilling means additionally includes splines transmitting a rotating motion and adapted to conduct the compressed air that used the percussion piston through the splines.