The invention relates to a composite shock absorber for a polycrystalline diamond compact bit, comprising a drilling tool body having a water inlet, an impact body having a water outlet and forming a shock absorption cavity, a disc spring group having an annular pressing sleeve, a cylindrical torsion bar spring which has an external thread and a spline, is connected to the drilling tool body through threads and extended into an impactor and connected thereto through the spline, and the annular pressing sleeve, wherein bit vibration impact force is transmitted therebetween through a torsion transmission joint, and a bearing group is arranged between the lower end surface of the annular pressing sleeve and an annular step of the impact body. The composite shock absorber can weaken damage of the slippage effect to polycrystalline diamond compact cutting teeth, absorb axial vibration from a drill stem and prolong the service life of the bit.

The invention relates to a composite shock absorber for a polycrystalline diamond compact bit, comprising a drilling tool body having a water inlet, an impact body having a water outlet and forming a shock absorption cavity, a disc spring group having an annular pressing sleeve, a cylindrical torsion bar spring which has an external thread and a spline, is connected to the drilling tool body through threads and extended into an impactor and connected thereto through the spline, and the annular pressing sleeve, wherein bit vibration impact force is transmitted therebetween through a torsion transmission joint, and a bearing group is arranged between the lower end surface of the annular pressing sleeve and an annular step of the impact body. The composite shock absorber can weaken damage of the slippage effect to polycrystalline diamond compact cutting teeth, absorb axial vibration from a drill stem and prolong the service life of the bit.

A piston actuated drilling tool includes a casing and a guide sleeve disposed within the casing in proximity to the top end of the casing. A piston is slidably disposed within the casing for reciprocating movement therein. The piston has a nose end arranged to reciprocate within the guide sleeve, wherein a first wear area of the tool occurs between the piston nose end and the guide sleeve. A replaceable wear bushing assembly is located within the guide sleeve at the first wear area. The replaceable wear bushing assembly can include either a static wear bushing or a sliding wear bushing.

A piston actuated drilling tool includes a casing and a guide sleeve disposed within the casing in proximity to the top end of the casing. A piston is slidably disposed within the casing for reciprocating movement therein. The piston has a nose end arranged to reciprocate within the guide sleeve, wherein a first wear area of the tool occurs between the piston nose end and the guide sleeve. A replaceable wear bushing assembly is located within the guide sleeve at the first wear area. The replaceable wear bushing assembly can include either a static wear bushing or a sliding wear bushing.

A pressure reversing valve for a fluid-actuated percussive drilling tool has a front thrust surface in communication with a rear chamber and a rear thrust surface in communication with a pressurized volume isolated from the flow coming from the source of pressurized fluid. The pressurized volume is in communication with a front chamber and allows the valve to take advantage of the imbalanced profile of the pressures inside the front and rear chambers that naturally occurs for enabling an asymmetric feeding process of the rear chamber that is also less sensitive to the bottom hole pressure.

The invention relates to a drill head and a device for drilling a bore in the ground, the drill head having a first unit coupleable with an inner drill pipe of a double drill pipe assembly and a second unit coupleable with the outer drill pipe of the double drill pipe assembly. By means of the inner drill pipe the first unit is rotatable about an axis of rotation relative to the second unit which is drivable by means of the outer drill pipe. The drill head has a sliding contact arrangement for establishing an electrical connection between the first unit and the second unit.

A hydraulic percussion device comprising a piston mounted for reciprocal motion within a cylinder to impact a percussion bit and a control valve to control reciprocation of the piston. A valve pilot line is arranged to switch the control valve based on the position of the piston within the cylinder, wherein the valve pilot line is alternately connected, by the reciprocal movement of the piston, to high and low pressure lines (P, T) via an undercut in the piston. The undercut is located at a portion of the piston having a diameter less than the maximum sealing diameter of the piston.

A down the hole drilling assembly has a top end coupled to a drill string and a bottom cutting end. The drilling assembly includes a piston arranged moveably inside a casing with a piston nose positioned at an axially bottom end and a top working chamber at a top end, a bottom working chamber at the bottom end, a driver sub having axially extending driver sub splines on an internal surface, a drill bit having an axially extending central bore including an elongate shank provided with axially extending shank splines on its outer surface for engagement with the driver sub splines to form a spline area, a guide sleeve forming a seal with the piston nose, the guide sleeve having an inner and outer surface, and at least one air passageway extending through the guide sleeve for fluidly connecting the bottom chamber to the spline area to provide lubrication thereto.

A down the hole drilling assembly has a top end coupled to a drill string and a bottom cutting end. The drilling assembly includes a piston arranged moveably inside a casing with a piston nose positioned at an axially bottom end and a top working chamber at a top end, a bottom working chamber at the bottom end, a driver sub having axially extending driver sub splines on an internal surface, a drill bit having an axially extending central bore including an elongate shank provided with axially extending shank splines on its outer surface for engagement with the driver sub splines to form a spline area, a guide sleeve forming a seal with the piston nose, the guide sleeve having an inner and outer surface, and at least one air passageway extending through the guide sleeve for fluidly connecting the bottom chamber to the spline area to provide lubrication thereto.

A hydraulic oscillation tool with variable stage, small pressure drop and strong impact based on radio frequency identification is provided. It includes a conversion connector, a disc spring upper bracket, a disc spring housing, a disc spring group, a multi-stage piston shaft, an upper piston sleeve, a first radial sealing ring, a double-female-buckle piston sleeve, a double-male-buckle piston sleeve, a second radial sealing ring, a double-female-buckle lower piston sleeve, an end piston, an impacting connector, a power housing, a power shaft end cap, a high torque turbine, a power shaft, a lower connector, a rotating valve, a bearing supporting ring, and a turbine special bearing. The hydraulic oscillation tool realizes the low pressure drop and strong impact, and thus the problems that with the continuous increase of horizontal length, excessive pressure drop will make the annular pressure drop sharply, and drilling fluid circulation is difficult are solved.