Abstract: An impactor for use with a directional boring machine having a drill string connectable to the impactor for pulling the impactor through an existing pipeline uses rotation of the drill string to drive an internal striker. The internal striker delivers impacts in the pulling direction to an impactor housing as the impactor housing tows a replacement pipe behind it. The impactor housing is free to move axially in response to impacts from the striker over a limited distance in the pulling direction independently of the replacement pipe and drill string.

Abstract: A method of slitting a flexible conduit in an underground bore, the conduit having entry and exit ends thereof exposed for access, includes: (1) fitting a retainer to flexible underground conduit adjacent to the entry end thereof, the retainer securing the flexible conduit to limit longitudinal movement thereof relative to the bore, (2) passing pulling means through the flexible conduit; (3) connecting the pulling means to a pipe slitter, and (4) pulling the pipe slitter through the retainer and flexible conduit to slit the conduit, the retainer holding the flexible conduit taut as the slitter passes through the conduit. In one embodiment, the retainer is a shoring clamp assembly including a pair of ring clamps that are secured onto a split end of the flexible conduit and transfer the longitudinal forces applied to the conduit during the slitting operation to an adjacent structure such as a pit wall, thereby holding the conduit taut during the slitting operation.

Abstract: An impactor for use with a directional boring machine for replacement of underground pipes includes a bursting head having a rearwardly opening recess and a front end opening that communicates with the recess. An inlet pipe is connected at its front end to a distal end of the drill string and extends into the recess of the bursting head through the front end opening. A striker is mounted for sliding movement along the inlet pipe, and a distributing mechanism responsive to pressure fluid supplied through the drill string and inlet pipe causes the striker to reciprocate in the rearwardly opening recess of the head to deliver forward impacts against the bursting head. The striker and distributing mechanism are mounted in a tubular housing, and a pulling connection is provided by which the impactor can be pulled by the drill string while the striker is delivering impacts against the head in the same direction as a pulling force exerted by the drill string.

Abstract: A joint connecting a pair of members rotatable about a common axis end to end includes a first member having a threaded end portion and a non-circular exterior surface rearwardly of the threaded end portion, a second member having a threaded socket wherein the threaded end portion of the second member can be engaged, and a non-circular exterior surface, a sleeve having a non-circular profile on an inner surface thereof whereby the sleeve can be slidably mounted on the non-circular exterior profiles of the first and second members when such profiles are brought into alignment by rotation of one member relative to the other in a manner effective to pass torque from one member to the other by means of the non-circular profiles, a first pair of alignable holes in the sleeve and first member to receive a fastener to secure the sleeve to the first member and a hole in the second member penetrating the threaded socket and positioned to receive a fastener to secure the second member to a third member in place of the

Abstract: A method for installation of an underground pipe includes an initial step of boring a pilot hole through the ground at a predetermined grade angle by extending a drill string having a steerable boring bit mounted thereon through the ground. Upon reaching an end location for the pilot hole, the bit is removed from the drill string, and an expander having a diameter greater than the pilot hole is attached to the drill string, which expander is backed by an impact device such as a pneumatic impactor including a striker that delivers repeated impacts to a rearwardly facing surface of the expander, and by a pipe drawn along behind the expander. The expander is pulled back through the pilot hole at the grade angle while the impactor is operated to aid progress of the expander through the ground and pull the pipe into place behind the expander.

Abstract: The invention provides a rock drilling bit with a plurality of cutting teeth raked into the cut of the drilling bit. Such teeth are oriented at an angle of at least about 30 degrees relative to an imaginary line normal to a front surface of the cutting head from which the cutting teeth project. Such an arrangement provides the desired shear cutting force against the rock face while simultaneously reducing the shock and vibration applied to sonde housing and the drill string. The bit according to the invention may further incorporate a rear, frustoconical crushing surface that defines a space or zone crescent-shaped in cross-section that narrows from front to rear, and an improved replacable tooth for use on a rock drilling bit.

Abstract: A pipe bursting system of the invention operates by compaction rather than by reaming. The system includes a conventional directional boring machine, a drill string, and a pipe burster attached to the terminal end of the drill string. A pipe burster according to the invention includes a frame having a front connecting portion configured for connection to a drill string that can pull and rotate the frame about an axis of rotation, at least two axles mounted on the frame, and rollers mounted on each axle. Each roller has a curved outer surface forwardly inclined towards the axis of rotation of the frame, whereby rotation of the frame about its axis of rotation results in rotation of the rollers when the curved outer surfaces of the rollers engage a cylindrical inner surface of a pipe being burst.

Abstract: A drill bit suited for impact-assisted directional boring in rock includes a bit body having a frontwardly facing, circular main cutting surface having a number of main cutting teeth disposed thereon. A gage cutter extends radially outwardly from the main cutting surface, which gage cutter mounts at least one frontwardly facing gage cutting tooth thereon suitable for cutting in a circle during straight boring and over an angle defined by less than a full rotation of the bit in order to steer the bit. A heel on an outer side surface of the bit body at a position opposite to and behind the gage tooth provides a reaction surface for the gage cutter. The bit body and gage cutter have a nearly circular side profile along a front portion thereof such that a maximum radial clearance between the side profile and a side wall of a hole being drilled is not greater than about 10 percent of the radius of a circle cut by the gage tooth.

Abstract: A drill head of directional boring includes a bit, a holder for a device for detecting angular orientation of the bit, and a hammer including a striker, wherein the bit assembly, holder and hammer are connected head to tail with the bit at a front end. The bit has a frontwardly facing main cutting surface having a plurality of main cutting teeth disposed thereon and a gage tower extending radially outwardly from the main cutting surface, which gage tower has at least one frontwardly facing gage cutting tooth thereon suitable for cutting over an angle defined by less than a full rotation of the bit. In one embodiment, the main cutting surface is substantially flat and circular and has fluid ejection ports thereon, and the drill head has passages for conducting a drill fluid therethrough to the ejection ports.

Abstract: A drill bit configured for use in horizontal directional boring includes a spoon-shaped body with a rearwardly angled or inclined arcuate front end face that widens from a leading edge to a trailing edge in a circumferential direction, the front face sloping rearwardly from a leading side surface to a trailing edge in a circumferential direction, the leading and trailing side surfaces extending rearwardly in from the front end face. The leading side surface is wider than the trailing side surface. In one configuration, the front end surface and leading side face are each provided with a plurality of carbide inserts or studs which may be arranged in a row.

Abstract: A pipe bursting system of the invention operates by compaction rather than by reaming. The system includes a conventional directional boring machine, a drill string, and a pipe burster attached to the terminal end of the drill string. A pipe burster according to the invention includes a frame having a front connecting portion configured for connection to a drill string that can pull and rotate the frame about an axis of rotation, at least two axles mounted on the frame, and rollers mounted on each axle. Each roller has a curved outer surface forwardly inclined towards the axis of rotation of the frame, whereby rotation of the frame about its axis of rotation results in rotation of the rollers when the curved outer surfaces of the rollers engage a cylindrical inner surface of a pipe being burst.

Abstract: An apparatus for mounting an electronic device therein for use in an underground boring machine includes an elongated housing having an elongated, lengthwise central cavity opening at one end thereof, a cartridge containing a sonde therein, which cartridge fits in the cavity; and a keying mechanism for securing the cartridge and sonde in a predetermined orientation relative to the housing when the cartridge is inserted into the cavity through the opening. One or more lengthwise fluid passages isolated from the cavity extend through the housing. A sonde housing of the invention may be used with a drill string and bit assembly in directional boring.

Abstract: A method of slitting a flexible conduit in an underground bore, the conduit having entry and exit ends thereof exposed for access, includes: (1) fitting a retainer to flexible underground conduit adjacent to the entry end thereof, the retainer securing the flexible conduit to limit longitudinal movement thereof relative to the bore, (2) passing pulling means through the flexible conduit; (3) connecting the pulling means to a pipe slitter, and (4) pulling the pipe slitter through the retainer and flexible conduit to slit the conduit, the retainer holding the flexible conduit taut as the slitter passes through the conduit. In one embodiment, the retainer is a shoring clamp assembly including a pair of ring clamps that are secured onto a split end of the flexible conduit and transfer the longitudinal forces applied to the conduit during the slitting operation to an adjacent structure such as a pit wall, thereby holding the conduit taut during the slitting operation.

Abstract: An improved starter rod connects a back reamer to the distal end of a drill string. The starter rod is an elongated body having a front end portion which has a first connecting portion configured for connecting the starter rod to the back reamer, a rear end portion having a second connecting portion configured for connecting the starter rod to the drill string, a fluid passage configured for conveying fluid from the drill string through the starter rod from the rear end to the front end, and a branch passage extending from the fluid passage to a side surface of the starter rod configured to pass part of the fluid in the fluid passage outside the starter rod. Generally, the front end portion of the starter rod is also used to connect to a drill head and thus has an outer diameter greater than the rear end which connects to the drill string. In a preferred embodiment, the branch passage opens rearwardly of the large diameter front end portion so that the lubricating fluid is injected in the hole ahead of it.

Abstract: A bit for directional boring according to the invention includes a bit body having a frontwardly facing sloped face effective for steering the bit in dirt. The sloped face defines a steering plane that defines an acute included angle relative to a lengthwise axis of rotation of the bit. A connection is provided at the rear of the bit body permitting the bit to be removably mounted at the lead end of a drill string, and one or more internal passages are provided in the bit body for carrying a drilling fluid to a front end of the bit body. A first cutting tooth is mounted on the bit body and extends frontwardly from the bit body at a first angle that causes the first tooth to cut along a first circular path as the bit rotates.

Abstract: A drill head for an apparatus for directional boring according to the invention includes a bit, a holder for a device for detecting angular orientation of the bit, and a hammer including a striker for delivering impacts to the bit, wherein the bit assembly, holder and hammer are connected head to tail with the bit at a front end. The bit of the invention has a frontwardly facing main cutting surface having a plurality of main cutting teeth disposed thereon and a gage tower extending radially outwardly from the main cutting surface, which gage tower has at least one frontwardly facing gage cutting tooth thereon suitable for cutting over an angle defined by less than a full rotation of the bit. The device for detecting angular orientation is in a predetermined alignment with the gage tower so that it determines the orientation of the gage tower relative to the axis of rotation of the drill head.

Abstract: An apparatus for pulling a conduit through a horizontal bore includes a drill head having a forward most end including a pocket configured to receive an elongated body; coupler, a coupling member including an elongate body configured to fit in the pocket and a connecting end extending outside of the drill head beyond the pocket configured for coupling the coupling member and drill head to a conduit pulling means, a hole in the drill head intersecting the pocket alignable with a retainer aperture in the elongate body and a retainer adapted to pass through the aperture and hole to secure the coupling member to the drill head. In one variation, a clevis and or bearing swivel passed through an eyelet in the connecting end is used with a rope, chain or cable to connect the drill head to a pipe puller for pulling a pipe or conduit through an underground horizontal bore.

Abstract: An impactor for use with a directional boring machine having a drill string connectable to the impactor for pulling the impactor through an existing pipeline uses rotation of the drill string to drive an internal striker. The internal striker delivers impacts in the pulling direction to an impactor housing as the impactor housing tows a replacement pipe behind it. The impactor housing is free to move axially in response to impacts from the striker over a limited distance in the pulling direction independently of the replacement pipe and drill string.

Abstract: A drill bit suited for impact-assisted directional boring in rock includes a bit body having a frontwardly facing, circular main cutting surface having a number of main cutting teeth disposed thereon. A gage cutter extends radially outwardly from the main cutting surface, which gage cutter mounts at least one frontwardly facing gage cutting tooth thereon suitable for cutting in a circle during straight boring and over an angle defined by less than a full rotation of the bit in order to steer the bit. A heel on an outer side surface of the bit body at a position opposite to and behind the gage tooth provides a reaction surface for the gage cutter. The bit body and gage cutter have a nearly circular side profile along a front portion thereof such that a maximum radial clearance between the side profile and a side wall of a hole being drilled is not greater than about 10 percent of the radius of a circle cut by the gage tooth.

Abstract: The invention provides a rock drilling bit with a plurality of cutting teeth raked into the cut of the drilling bit. Such teeth are oriented at an angle of at least about 30 degrees relative to an imaginary line normal to a front surface of the cutting head from which the cutting teeth project. Such an arrangement provides the desired shear cutting force against the rock face while simultaneously reducing the shock and vibration applied to sonde housing and the drill string. The bit according to the invention may further incorporate a rear, frustoconical crushing surface that defines a space or zone crescent-shaped in cross-section that narrows from front to rear, and an improved replacable tooth for use on a rock drilling bit.