In an embodiment, a method of fabricating a polycrystalline diamond compact is disclosed. The method includes sintering a plurality of diamond particles in the presence of a metal-solvent catalyst to form a polycrystalline diamond body; leaching the polycrystalline diamond body to at least partially remove the metal-solvent catalyst therefrom, thereby forming an at least partially leached polycrystalline diamond body; and subjecting an assembly of the at least partially leached polycrystalline diamond body and a cemented carbide substrate to a high-pressure/high-temperature process at a pressure to infiltrate the at least partially leached polycrystalline diamond body with an infiltrant. The pressure of the high-pressure/high-temperature process is less than that employed in the act of sintering of the plurality of diamond particles.

In an embodiment, a method of fabricating a polycrystalline diamond compact is disclosed. The method includes sintering a plurality of diamond particles in the presence of a metal-solvent catalyst to form a polycrystalline diamond body; leaching the polycrystalline diamond body to at least partially remove the metal-solvent catalyst therefrom, thereby forming an at least partially leached polycrystalline diamond body; and subjecting an assembly of the at least partially leached polycrystalline diamond body and a cemented carbide substrate to a high-pressure/high-temperature process at a pressure to infiltrate the at least partially leached polycrystalline diamond body with an infiltrant. The pressure of the high-pressure/high-temperature process is less than that employed in the act of sintering of the plurality of diamond particles.

A polycrystalline diamond drill bit for percussion drilling, in small hole high silica ground is disclosed which has a cutting face having an inner flat face and an outer beveled peripheral surface, a number of first polycrystalline diamond tipped inserts having a first diameter inserted into the inner flat face and the outer beveled peripheral surface, and a number of second polycrystalline diamond tipped inserts having a second diameter inserted into the inner flat face, with the second diameter being different than the first diameter. The cutting angle and the radius of the tip of each insert in addition to the diameter of the inserts, provide for use of a machine thrust pressure and machine torque pressure at low ranges when the PCD bits are used in percussion drilling. The percussion drilling, with larger bits, may be used for rotary oil drilling, and operating at a machine thrust and torque of less than 20 Bar.

A polycrystalline diamond drill bit for percussion drilling, in small hole high silica ground is disclosed which has a cutting face having an inner flat face and an outer beveled peripheral surface, a number of first polycrystalline diamond tipped inserts having a first diameter inserted into the inner flat face and the outer beveled peripheral surface, and a number of second polycrystalline diamond tipped inserts having a second diameter inserted into the inner flat face, with the second diameter being different than the first diameter. The cutting angle and the radius of the tip of each insert in addition to the diameter of the inserts, provide for use of a machine thrust pressure and machine torque pressure at low ranges when the PCD bits are used in percussion drilling. The percussion drilling, with larger bits, may be used for rotary oil drilling, and operating at a machine thrust and torque of less than 20 Bar.

Drill bit insert with a sintered cemented carbide body including a hard phase of tungsten carbide (WC) and a binder phase wherein the cemented carbide comprises 5.0-7.0 wt % Co, 0.10-0.35 wt % Cr, and a Cr/Co weight ratio of 0.015-0.058. The cemented carbide body has a hardness of 1520-1660 Hv30 and a toughness of K1.sub.c10.0 both measured in the bulk at the center of the longitudinal axis through the center of the insert, or 5 mm from any surface of the insert. The insert further has a surface toughness K1.sub.c12.0 measured at 0.5 mm below the surface of the body in a transverse direction to the longitudinal axis the insert. The invention also relates to a drill bit comprising the insert and the use of such a drill bit for drilling.

Drill bit insert with a sintered cemented carbide body including a hard phase of tungsten carbide (WC) and a binder phase wherein the cemented carbide comprises 5.0-7.0 wt % Co, 0.10-0.35 wt % Cr, and a Cr/Co weight ratio of 0.015-0.058. The cemented carbide body has a hardness of 1520-1660 Hv30 and a toughness of K1.sub.c10.0 both measured in the bulk at the center of the longitudinal axis through the center of the insert, or 5 mm from any surface of the insert. The insert further has a surface toughness K1.sub.c12.0 measured at 0.5 mm below the surface of the body in a transverse direction to the longitudinal axis the insert. The invention also relates to a drill bit comprising the insert and the use of such a drill bit for drilling.

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 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.