Abstract: A retaining assembly for a cylindrical member and support sleeve in the bore of a component of a DTH. The cylindrical member and support sleeve may, for example, be a foot valve assembly for insertion into a counter bore in a bit. The cylindrical member has a cylindrical member rigidity and at least a portion of the support sleeve has a rigidity greater than the cylindrical member rigidity. A gap is provided between the sleeve and the component bore of the DTH. The cylindrical member deforms in the gap, resulting in the cylindrical member being fixedly sandwiched between the support sleeve and the component bore.

Abstract: A variable frequency down hole drill, includes a drill bit, a reciprocating piston operable to deliver an impact load to the drill bit, and means for changing the frequency with which the piston delivers impact loading to the drill bit, also resulting in a change in overall power of the drill. The means for changing frequency and overall power may operate during continuous operation of the drill. The means for changing the frequency and overall power may include a valve for selectively changing the effective volume of a drive or return chamber, an actuator for changing the timing of placing the drive or return chamber in communication with exhaust, or a system for changing the frequency in response to sensing an predetermined operating parameter of the drill, such as pressure or piston position.

Abstract: A retaining assembly for a cylindrical member and support sleeve in the bore of a component of a DTH. The cylindrical member and support sleeve may, for example, be a foot valve assembly for insertion into a counter bore in a bit. The cylindrical member has a cylindrical member rigidity and at least a portion of the support sleeve has a rigidity greater than the cylindrical member rigidity. A gap is provided between the sleeve and the component bore of the DTH. The cylindrical member deforms in the gap, resulting in the cylindrical member being fixedly sandwiched between the support sleeve and the component bore.

Abstract: A method for assembling a down hole drill comprises the steps of providing a cylindrical casing and a fluid distributor cylinder. Prior to assembly, the casing inner diameter is smaller than the fluid distributor cylinder outer diameter. A preassembly thermal treatment step is executed, in which the casing is heated to increase the casing inner diameter, or the distributor cylinder is cooled to decrease the distributor outer diameter, or both the casing is heated and the distributor cylinder is cooled. The distributor cylinder is then inserted into the cylindrical casing, and threaded into threads inside the cylindrical casing. Thermal energy is transferred between the cylindrical casing and the distributor cylinder, causing the casing inner diameter and the fluid distributor cylinder outer diameter to return to their preassembly sizes. This results in an interference fit along the outer surface of the distributor cylinder and the inner surface of the cylindrical casing.

Abstract: A fluid distributor cylinder is for a percussive drill assembly that includes a casing having an inner circumferential surface defining a central bore, a central axis extending through the bore, a bit movably coupled with the casing and a piston movably disposed within the casing bore. The distributor cylinder includes a generally tubular body disposeable within the casing bore and having first and second ends, a central axis extending generally between the first and second ends, an outer circumferential surface. At least a section of the outer surface is configured to engage with the inner surface of the casing so to form an interference fit between the body and the casing. The cylinder includes an exterior thread and/or a radially-extending shoulder configured to releasably engage with the casing inner surface so as to substantially prevent axial displacement of the distributor body with respect to the casing.

Abstract: A bit assembly is for a percussive drill that includes a casing with an interior chamber and includes a bit connectable with the casing and having a longitudinal bore and an axis through the bore. The bore has a retainer portion with one or more generally conical inner surfaces extending circumferentially about and facing generally toward the axis. A generally cylindrical valve has a longitudinal passage with an inlet fluidly connectable with the casing chamber and an outlet fluidly connectable with the bit central bore and an axis through the passage. An engagement portion with at least one generally conical outer surface extends circumferentially about and faces generally away from the valve axis. The valve engagement portion is disposable within the bit bore retainer portion such that the valve conical outer surface is disposed within and against the bit conical inner surface to retain the valve coupled with the bit.

Abstract: A variable frequency down hole drill, includes a drill bit, a reciprocating piston operable to deliver an impact load to the drill bit, and means for changing the frequency with which the piston delivers impact loading to the drill bit, also resulting in a change in overall power of the drill. The means for changing frequency and overall power may operate during continuous operation of the drill. The means for changing the frequency and overall power may include a valve for selectively changing the effective volume of a drive or return chamber, an actuator for changing the timing of placing the drive or return chamber in communication with exhaust, or a system for changing the frequency in response to sensing an predetermined operating parameter of the drill, such as pressure or piston position.

Abstract: A fluid distributor cylinder is for a percussive drill assembly that includes a casing having an inner circumferential surface defining a central bore, a central axis extending through the bore, a bit movably coupled with the casing and a piston movably disposed within the casing bore. The distributor cylinder includes a generally tubular body disposeable within the casing bore and having first and second ends, a central axis extending generally between the first and second ends, an outer circumferential surface. At least a section of the outer surface is configured to engage with the inner surface of the casing so to form an interference fit between the body and the casing. The cylinder includes an exterior thread and/or a radially-extending shoulder configured to releasably engage with the casing inner surface so as to substantially prevent axial displacement of the distributor body with respect to the casing.

Abstract: A bit assembly is for a percussive drill that includes a casing with an interior chamber and includes a bit connectable with the casing and having a longitudinal bore and an axis through the bore. The bore has a retainer portion with one or more generally. conical inner surfaces extending circumferentially about and facing generally toward the axis. A generally cylindrical valve has a longitudinal passage with an inlet fluidly connectable with the casing chamber and an outlet fluidly connectable with the bit central bore and an axis through the passage. An engagement portion with at least one generally conical outer surface extends circumferentially about and faces generally away from the valve axis. The valve engagement portion is disposable within the bit bore retainer portion such that the valve conical outer surface is disposed within and against the bit conical inner surface to retain the valve coupled with the bit.