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.

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.

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 bit (11) for the drilling, in particular the rotary percussive drilling, of a hole, in particular a tap hole of a melting furnace, the drill bit (11) comprising a drill head (10), which has at least one hard material insert (16), and a base body (12) for connecting the drill bit to a driving element, the hard material insert (16) being inserted into a seat, which is formed in an axial end face (13) of the drill head (10), in such a manner that at least a head cutting edge (18) of the hard material insert (16) protrudes beyond the axial end face (13), wherein the seat has a flank portion and a mating flank portion located opposite the flank portion, between which the hard material insert (16) is disposed, the flank portion, which is disposed opposite a recess formed in the hard material insert (16), being provided with a material projection (35) which is at least partially made of a welding material, is bonded to the drill head (10) via the welding material and protrudes into the recess so as to establish a form-fitting connection with the hard material insert (16).

A drill bit (11) for the drilling, in particular the rotary percussive drilling, of a hole, in particular a tap hole of a melting furnace, the drill bit (11) comprising a drill head (10), which has at least one hard material insert (16), and a base body (12) for connecting the drill bit to a driving element, the hard material insert (16) being inserted into a seat, which is formed in an axial end face (13) of the drill head (10), in such a manner that at least a head cutting edge (18) of the hard material insert (16) protrudes beyond the axial end face (13), wherein the seat has a flank portion and a mating flank portion located opposite the flank portion, between which the hard material insert (16) is disposed, the flank portion, which is disposed opposite a recess formed in the hard material insert (16), being provided with a material projection (35) which is at least partially made of a welding material, is bonded to the drill head (10) via the welding material and protrudes into the recess so as to establish a form-fitting connection with the hard material insert (16).

A fluid operated drilling device for drilling a hole said device having a hammer, a rotation device and a drill rod. The hammer includes a tubular main body, a back head, a cylindrical piston housing, a reciprocating piston, a space, a valve unit and a fluid pressure supply unit. A hollow portion of the piston is open to lead pressurized operating fluid directly to the hollow portion from the fluid pressure supply passage. The hammer includes an axial exhaust passage formed between the main body and the piston housing. The valve unit includes a valve exhaust passage and the piston has a lower part and an upper part detachably connected to each other. The invention also relates to a method for drilling a hole using the fluid operated drilling device.

A fluid operated drilling device for drilling a hole said device having a hammer, a rotation device and a drill rod. The hammer includes a tubular main body, a back head, a cylindrical piston housing, a reciprocating piston, a space, a valve unit and a fluid pressure supply unit. A hollow portion of the piston is open to lead pressurized operating fluid directly to the hollow portion from the fluid pressure supply passage. The hammer includes an axial exhaust passage formed between the main body and the piston housing. The valve unit includes a valve exhaust passage and the piston has a lower part and an upper part detachably connected to each other. The invention also relates to a method for drilling a hole using the fluid operated drilling device.

This disclosure relates to a percussive drill bit comprising PCD studs and a hard facing material that is strategically located to minimise stud pop outs and the amount of hard facing material used.