Abstract: A portion of a drilling tool having a drill bit driven in a rotating motion and in an axial percussion motion comprises a keyed connection between the drill bit and a driver sub that receives the drill bit. The keyed connection comprises a transverse member coupling the drill bit to a driver sub having a bore within which the drill bit is received. The driver sub has a pair of opposed openings and the bit has an axial slot. The openings and the slot are dimensioned to receive the transverse member. The keyed connection transmits force to the drill bit to drive the drill bit during operation and removably secures it in the driver sub.

Abstract: A down-the-hole percussive hammer for rock drilling includes a cylindrical casing and a drill bit disposed at a front end of the casing. The drill bit includes a forwardly facing cutting surface and a center longitudinal passage extending forwardly through a rearwardly facing rearwardmost end surface of the drill bit. The passage includes a rearwardly facing impact surface. A piston is mounted in the casing longitudinally behind the drill bit for reciprocation in a longitudinal direction. The piston includes a front portion sized to enter the center passage of the drill bit and strike the impact surface of the drill bit during each forward stroke of the piston. The impact surface of the drill bit is spaced forwardly from the rearwardmost end surface of the drill bit by a distance of at least ten percent of a total longitudinal length of the drill bit.

Abstract: In an air actuated down-the-hole hammer for rock drilling, a piston reciprocates within a casing to impact against a rear anvil surface of a drill bit. Upon making such impact, some fluid disposed between the impact surface and the anvil surface is forced radially inwardly toward a foot valve which fluidly inner connects central passages extending through the piston and the drill bit. In order to minimize the wear of the foot valve imposed by such forced fluid, either the piston or the drill bit includes a projection extending around a radially inner peripheral edge thereof for deflecting the forced fluid in a direction having an axial component to minimize an impact force of the fluid against the foot valve.

Abstract: A down-the-hole percussive drill comprises a casing, a drill bit mounted at a lower end of the casing, a hollow feed tube fixed within the casing and extending along a center axis thereof, and a piston mounted for axial reciprocation within the casing for transmitting impacts to the drill bit. The upper portion forms a downwardly facing surface at the junction between the upper and lower portions. Passages for conducting lubricant-containing pressurized air are formed in the piston. At least one of those passages constitutes a vertical recess formed in the outer periphery of the piston. The piston includes a radially outwardly projecting rib disposed between upper and lower ends of the recess. Air is blocked from traveling past the rib until the rib becomes located opposite an annular groove formed in an inner surface of the casing.

Abstract: In an air actuated down-the-hole hammer for rock drilling, a piston reciprocates within a casing to impact against a rear anvil surface of a drill bit. A foot valve extends axially between the piston and the drill bit. The anvil surface is inclined downwardly in a radially outward direction to cause liquid on the anvil surface to be discharged in a direction away from the foot valve, to prevent damage to the foot valve which could occur if piston impacts were able to create high-speed liquid streams contacting the foot valve.

Abstract: A down-the-hole percussive drill comprises a casing, a drill bit mounted at a lower end of the casing, a hollow feed tube fixed within the casing and extending along a center axis thereof, and a piston mounted for axial reciprocation within the casing for transmitting impacts to the drill bit. The piston has a stepped configuration in that a lower portion thereof is of smaller outer diameter than an upper portion thereof. The upper portion forms a downwardly facing surface at the junction between the upper and lower portions. Air-conducting passages are formed in the upper portion of the piston and are supplied with pressurized air from the hollow feed tube. One of those passages intersects the downwardly facing surface of the upper portion of the piston. The hollow feed tube is mounted to a top sub of the drill by pins which are mounted in the top sub and extend radially into a sidewall of the feed tube, the pins being situated outside of the central passage.

Abstract: The present invention relates to a drilling tool for percussive drilling by means of a top hammer unit, which unit gives compressive pulses. The tool comprises at least one drill tube (12) and a drill bit (11), which cooperates via a connection. The drill bit comprises a bit head (13) provided with crushing means (15) and a shank (17). A shoulder (20) is provided in connection with the bit head, said bit portion having a first abutment surface (21) facing towards a free end of the tube. The free end of the tube facing towards the drill bit is povided with a second abutment surface (23), said top hammer unit being provided to tannsfer compressive pulses to the tube. Each compressive pulse is transferred to the drill bit via the impact surfaces (21, 23). The tube and the drill bit comprise cooperating device (19, 24, 25) for driving and retaining. The tool is defined by that it has a relation between the length of the shank and the length of the bit head that is 5 or more.

Abstract: A rock drilling tool for percussive drilling includes a drill bit and a drill tube cooperating by means of shoulder abutment in a threaded connection. The connection includes at least one male thread and a female thread. The male thread is provided on a shank being an integral part of the drill bit. The drill bit is provided with a shoulder at the inner end of the shank, the shoulder having an abutment surface facing towards the free end of the shank. The female thread is provided in the drill tube and the free end of the drill tube is provided with an impact surface. The threads are cylindrical. The combination of shoulder abutment with a short head provides straight energy transfer at a rock drilling tool.

Abstract: The present invention relates to a hammer device, preferably a down-the-hole hammer, including a drill bit (11) and a piston (10) reciprocating therebehind to periodically strike the drill bit. The drill bit (11) includes front (11a) and rear (11b) portions of different impedance, and the piston (10) includes front (10b) and rear (10a) portions of different impedance. In the drill bit, the front portion (11a) has a larger impedance than the rear portion (11b). In the piston, the rear portion (10a) has a larger impedance than the front portion (10b). The length of the drill bit front portion (11a) is about twice the length of the drill bit rear portion (11b). The length of the piston rear portion (10a) is about twice the length of the piston front portion (11b). The invention further relates to a drill bit (11) and a piston (10), per se.

Abstract: A down-the-hole hammer includes a drill bit and a piston reciprocating therebehind to periodically strike the drill bit. The drill bit includes front and rear portions of difference impedance, and the piston includes front and rear portions of difference impedance. In the drill bit, the front portion has a larger impedance than the rear portion. In the piston, the rear portion has a larger impedance than the front portion.