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 ground engagement 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 first member, the third member having a hole in a threaded end portion thereof alignable with the hole in the second member.

CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Patent Application No. 61/365,961, filed Jul. 20, 2010, the contents of which are incorporated fully herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to rotary boring and, in particular to an improved joint for connecting two rotatable components of a boring system. 
       SUMMARY OF THE INVENTION 
       [0003]    The present invention is directed to a pipe joint for use in rotary boring operations. The pipe joint comprises a first member, a second member, and a ground engaging member. The first member has a non-circular exterior surface and a threaded socket. The second member comprises a threaded end portion for mating engagement with the threaded socket and a non-circular exterior surface portion corresponding to the non-circular exterior surface of the first member. The ground engaging member has a non-circular internal surface and an outer surface for enlarging a borehole. The non-circular internal surface corresponds to the non-circular exterior surface of both the first member and the second member for slidably mounting the ground engaging member on the non-circular exterior surfaces of the first member and the second member when the threaded socket of the first member is engaged with the threaded end portion of the second member and to transmit torque between the first member and the second member. Alignable holes are formed in the ground engaging member and the second member for receiving a fastener to secure the ground engaging member to the second member. 
         [0004]    The present invention is further directed to a rotary boring system comprising a rotary machine, a drill string, and a downhole tool. The drill string has a first end and a second end. The first end is operatively connected to the rotary drive machine to drive rotation of the drill string. The downhole tool comprises a first member, a second member, and a ground-engaging member. The first member is connected to the second end of the drill string and comprises a non-circular exterior surface and a connector socket. The second member comprises a connector portion for mating engagement with the connector socket and a non-circular exterior surface portion corresponding to the non-circular exterior surface of the first member. The ground engaging member has a non-circular internal surface and an outer surface for enlarging a borehole. The non-circular internal surface corresponds to the non-circular surface of both the first member and the second member for slidably mounting the ground engaging member on the non-circular surfaces of the first member and the second member when the connector end portion is engaged with the connector socket and to transmit torque between the first member and the second member. The downhole tool further comprises alignable holes in the ground engaging member and the second member for receiving a fastener to secure the ground engaging member to the second member. 
         [0005]    Further still, the present invention is directed to a method for making boreholes using a boring machine having a rotary drive system capable of rotating and axially advancing or retracting a downhole tool attached to a drill string. The method comprises the steps of connecting a first end of an elongate first member to the drill string, wherein the first member comprises a first end and a second end, the second end comprising a socket and a non-circular outer surface. A ground engaging member having a correspondingly non-circular internal surface is slid over the second end of the first member. A second member is engaged to the socket of the first member and oriented such that a non-circular surface formed thereon fits within the non-circular internal surface of the ground engaging member to pass rotation of the drill string and the first member to the ground engaging member and the second member by means of the non-circular surfaces. 
         [0006]    Still yet, the present invention is directed to an adapter for connecting a pair of drilling components. The adapter comprises a first member, a second member, and a ground engaging member. The first member has a non-circular exterior surface and threaded socket. The second member has a threaded end portion and a non-circular exterior surface rearward of the threaded end portion. The threaded end portion is engagable with the threaded socket of the first member. The ground engaging member has a non-circular profile on an inner surface thereof whereby the ground engaging member is 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. 
         [0007]    The present invention is further directed to a pipe joint for use in rotary boring operations. The pipe joint comprises a first member, a second member, and a ground engaging member. The first member has a non-circular exterior surface and a first connector. The second member comprises a second connector for mating engagement with the first connector and a non-circular exterior surface portion corresponding to the non-circular exterior surface of the first member. The ground engaging member has a non-circular internal surface and an outer surface for enlarging a borehole. The non-circular internal surface corresponds to the non-circular exterior surface of both the first member and the second member for slidably mounting the ground engaging member on the non-circular exterior surfaces of the first member and the second member when the first connector is engaged with the second connector and to transmit torque between the first member and the second member. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a side view of a first pipe joint according to the invention including a first member, a pulling adapter, and a ground engaging member. 
           [0009]      FIG. 2  is a longitudinal section view along line A-A of  FIG. 1 . 
           [0010]      FIG. 3  is a cross section view of the device of  FIG. 2  along section line B-B showing details of engaged non-circular profiles. 
           [0011]      FIG. 4  is an isometric view of the pipe joint of  FIGS. 1-3  in exploded view. 
           [0012]      FIG. 5  is a side view of the device shown  FIGS. 1-3  having an additional backreaming tool in a stacked arrangement to provide progressive upsizing. 
           [0013]      FIG. 6  is an isometric view of the device of the present invention showing a boring tool connected to the first member. 
       
    
    
     DESCRIPTION OF THE INVENTION 
       [0014]    Rotary boring systems for making holes through soil are well known. The boring system generally includes drill string comprising a series of drill pipes joined end to end. The drill string is rotated by a rotary drive machine and pushed or pulled through the ground by means of a powerful hydraulic device such as a hydraulic cylinder or a gear rack actuated by a hydraulic motor. A boring head for boring in soil, rock or both is disposed at the end of the drill string and may include an ejection nozzle for water or other drilling fluid to assist in boring. In other applications, tools such as pipe bursters, impactors, slitters and pullers are used to slit, burst and replace existing underground pipelines. Reamers may be used along or in combination with any of the aforementioned tools to upsize a borehole. 
         [0015]    In most horizontal boring operations a pilot bore is drilled between a starting point and an end point. Once the boring tool reaches the end point, whether the surface of the ground or a pit, the boring tool is removed and a backreamer may be attached to the drill string. The backreamer is used to upsize the borehole to meet or slightly exceed the outer diameter of the product pipe towed into the bore during pullback. Easy attachment of the product pipe to a backreamer assembly in a small access pit is disclosed in U.S. Patent application number 2002/0112890, the contents of which are incorporated herein by reference. If attempting to make a switch out in a pit, the swap will require enlargement of the access pit lengthwise to accommodate the length of the backreamer and its connection components. Ideally, the operator would like the change of tools to occur rapidly and be easily accomplished without the need to dig a large access pit. The present invention allows an operator to change tools at the downhole end of a drill string in a small access pit. 
         [0016]    Turning now to the figures and specifically to  FIG. 1 , there is shown therein a pipe joint  10  of the present invention. As used herein the term “pipe joint” may mean a downhole tool used in rotary boring operations, an adapter used to connect various drilling tools to the downhole end of a drill string, or the connection of two drilling system components. The pipe joint  10  of  FIG. 1  comprises a first member  12 , a second member  14 , and a ground engaging member  16 . The first member  12  has a first end  18  and a second end  20  ( FIG. 2 ). The first end  18  of the first member  12  may have a diametral upset  22  for a yet to be described purpose. The second end  20  of the first member  12  may be disposed within the ground engaging member  16 . 
         [0017]    The ground engaging member  16  shown in  FIG. 1  comprises a frustoconical outer surface  24  having a plurality of carbide cutting teeth  26  and a helical groove  28 . A plurality of orifices  30  may be spaced about the outer surface  24  to eject fluid from the member into the borehole. The ground engaging member  16  further comprises alignable holes  32  used to connect the ground engaging member to either the first member  12  or the second member  14  using a fastener  33 . In  FIG. 1  the alignable holes  32  are shown positioned to connect the ground engaging member to the second member  14 . The second member  14  will be discussed in more detail hereinafter, but as shown in  FIG. 1  the second member may comprise a clevis  34  formed for receiving any generic connection to a swivel and product pulling device as may be required to install a utility in the borehole. Cross holes  36  formed in the clevis are on a common axis to allow use of a pin or bolt (not shown) to carry shear forces during towing of the utility behind the pipe joint  10 . 
         [0018]    Turning now to  FIG. 2 , there is shown a longitudinal section view of the pipe joint  10  of  FIG. 1  along section line A-A. The first member  12  may be elongate and comprise the first end  18  having coupling member  38  for coupling the first member to the drill string (not shown). The second end  20  of the first member  12  may comprise a non-circular exterior surface  40  ( FIG. 4 ) and a first connector comprising a threaded socket  42 . The first connector  42  and non-circular exterior surface  40  may form an upset at the second end  20  of the first member  12 . Likewise, the coupling member  38  may form an upset  22  at the first end  18  of the first member  12 . A fluid passage  44  may extend from the first end  18  to the second end  20  to carry fluid such as drilling mud to the ground engaging member  16 . 
         [0019]    The second member  14  comprises a second connector, depicted as a threaded end portion  46  for mating engagement with the first connector  42 . When threads are used, as shown in  FIG. 2 , the first member  12  and second member  14  are rotated relative to each other to matingly engage the threaded end portion  46  of the second member  14  within the threaded socket  42  of the first member  12 . One skilled in the art will appreciate that the first connector  42  and second connector  46  may include any conventional coupling or joint used to connect drilling tools and may comprise part of such a tool. One such coupling system is known commercially as Splinelok™ wherein interlocking splines that pass torque from the drill string to a tool is described in Wentworth et al., published U.S. Patent Application Serial No. 2001/0017222, the disclosure of which is incorporated herein by reference for all purposes. 
         [0020]    As illustrated, the second connector  42  is a tapered threaded end portion disposed between a central collar  48  and a front face  50  of the second member  14 . The second member  14  also comprises a hole  52  that is alignable with a corresponding hole  32  in ground engaging member  16 . Alignable holes  52  and  32  allow the second member to be locked in position relative to the ground engaging member  16  with fastener  33 . A first stop member  53  is formed on the second member  14  to abut the ground engaging member  16  and defines a first boundary of the central collar  48 . A second stop member  62  defines a second boundary of the central collar  48  and abuts a front face  64  of the first member  12 . 
         [0021]    An O-ring  54  may be positioned adjacent front face  50  of the second member  14  and against a wall  56  of the first member  12  in a groove  58 . The O-ring  54  protects the socket  42 , wall  56  and threads  46  from ingress of abrasive materials that would exacerbate wear during operations. The O-ring  54  also prevents the egress of drilling fluid as it passes from passage  44  into passage  60  formed in the second member  14 . A radial passage  65  is formed in the second member  14  allow fluid to flow from the internal passage  60  into the cross-sectional clearance area  68  ( FIG. 3 ) to a circumferential gallery  70 . The fluid then flows through the discharge ports  30  ( FIG. 1 ) to mix with the soil thereby facilitating the ground engagement operation. The cross-sectional clearance area  68  continues forward for the length of the ground engaging member  16  and a fraction of the fluid delivered will flow to the front end  72  of the ground engaging member to reduce wear on the edge when engaged with the soil. Carbide teeth  26  and the tapered helical groove  28  produce shearing and mixing between soil and drill fluid as the drill string and ground engaging member are rotated. 
         [0022]      FIGS. 2 and 3  illustrate the ground engaging member  16  comprises a non-circular internal surface  66  positioned over the central collar  48  of the second member  14 . The outer surface  24  may be frustoconical for enlarging the borehole. The non-circular internal surface  66  corresponds to the non-circular exterior surface  40  ( FIG. 4 ) of the both the first member  12  and the second member  14  for slidably mounting the ground engaging member  16  on the non-circular exterior surfaces of the first member and the second member when the first connector  42  is coupled to the second connector  46  to transmit torque between the first member  12  and the second member  14 . 
         [0023]    In operation, joint  10  is assembled by sliding ground engaging member  16  over the first member  12 . Threaded end portion  46  of second member  14  is then screwed into threaded socket  42  and tightened to the desired level. After threaded end portion  46  of second member  14  has been tightened to the desired degree in threaded socket  42 , the alignment of exterior surfaces  48  and  40  is checked. If the profiles of the non-circular exterior surfaces  48  and  40  are not aligned ground engaging member  16  will not slide over second member  14 , consequently, the second member is unscrewed or backed off until the profiles of exterior surfaces  48  and  40  are aligned. The ground engaging member  16  is then slid along first member  12  and over non-circular exterior surface  48  of the second member  14 . In the event that the profiles of exterior surfaces  48  and  40  are not aligned when second member  14  is tightened to the desired level, the degree to which the second member will have to be backed off or loosened to align the profiles depends upon the selected profile. For example, in the case of an octagonal profile, the angle between the centers of each flat surface is 360/8 or 45°. Thus, in case of octagonal profile, the maximum number of degrees that second member  14  may have to be backed off after tightening to align the octagonal profiles of exterior surfaces  48  and  40  is the rotational difference between successive surfaces, or 45°. 
         [0024]    After the ground engaging member has been positioned over the second member  14 , a retaining bolt or screw  33  is passed through hole  32  in the ground engaging member and engaged with bolt hole  52  in the second member, locking the ground engaging member onto the second member. Shoulder  53  prevents the ground engaging member  16  from sliding rearward as ground engagement forces are applied. Bolts  33  retain ground engaging member  16  should the normal direction of the drill string be reversed. Preferably, one or more of alignable holes  52  and  32  and bolt  33  are provided with NPT (National Pipe Thread) threads which provide improved retention and greater shear area than convention straight threads. 
         [0025]    Continuing in  FIGS. 2 and 3 , fluid such as drilling mud is passed along central bore  44  of first member  12 , continuing flow into internal passage  60  of the second member  14 . The fluid will then pass through the wall of the second member  14  through radial passage  65 . The flow rate of such fluid may be metered through an orifice formed in passage  65 . Threading of passage  65  helps to maintain the position of the orifice so as not to maintain offset between the orifice and the inner surface of the ground engaging member  16 . After flowing through passage  65 , the fluid may make its way through a cross sectional clearance  68  along the length of the ground engaging member to the circumferential gallery  70 . Finally, the fluid flows through the discharge port  30  ( FIG. 1 ) to mix with the soil thereby facilitating the ground engagement operation. The sectional clearance may continue forward for the length of the ground engaging member and a fraction of the fluid delivered will flow to the front end  72 , thereby reducing wear on this edge when engaged with the soil. 
         [0026]    Turning now to  FIG. 4 , an embodiment of the pipe joint of the present invention is shown in exploded view. First member  12  comprises an elongate tubular member having a first end  18  and a second end  20 . The first end  18  has an upset  22  having a threaded connector  38  ( FIG. 2 ) for connecting the first member to the drill string (not shown). The second end  20  may comprise the non-circular exterior surface  40  and a connector socket. The second member  14  comprises the connector portion for mating engagement with the connector socket  42  and a non-circular surface  48  corresponding to the non-circular exterior surface  40  of the first member  12 . The second member  14  may comprise a front face  50  and a central collar formed by the non-circular exterior surface  48 . The connector end portion  46  is disposed between the front face  50  and the central collar. 
         [0027]    The ground engaging member  16  comprises a frustoconical backreaming member having a plurality of helical grooves  28  and carbide teeth  26  for enlarging the borehole. The ground engaging member  16  comprises a non-circular internal surface that corresponds to the non-circular exterior surfaces of the first member and the second member for slidably mounting the ground engaging member on the non-circular surfaces of the first member and the second member when the connector end portion  46  is engaged with the connector socket  42 . Such connection allows for the transmission of torque between the first member and the second member. 
         [0028]    Alignable holes  32  and  52  are formed in the ground engaging member  16  and the second member  14  receive fasteners  33  to secure the ground engaging member  16  to the second member  14 . One skilled in the art will appreciate that alignable holes may alternatively be formed in the first member to secure the ground engaging member to the first member instead of the second member or in addition to the holes formed in the second member. 
         [0029]      FIG. 5  demonstrates a use of the pipe joint of the present invention with an alternative large reamer weldment  74  sized to continue ground engagement work to open the bore while permitting fluid flow from the ground engagement member  16  as well as ports  82  formed in the exterior surface of the reamer  74 . Reamer  74  may be joined to the second member  14  by a weld  76 . A product pipe (not shown) is towed at product connector  34  behind the combination of stacked reamers. Connector  34  is joined to reamer  74  by weld  78 . As shown in  FIG. 5 , the fluid flow passage of the second member  14  may continue, in fluid communication with internal passage  80  formed in reamer  74  so that fluid may be injected into the borehole from the reamer through radial ports  82  formed in the reamer. 
         [0030]    Turning now to  FIG. 6 , a downhole tool constructed in accordance with the present invention is shown. The downhole tool comprises the previously described first member  12 , second member  14  and ground engaging member  16  of  FIGS. 1-5 . However, the second member  14  of  FIG. 6  comprises a boring tool  84 . The boring tool  84  shown in  FIG. 5  comprises a directional drill bit commonly used in horizontal drilling operations. One skilled in the art will appreciate the second member  14  may comprise several different boring tools used either to cut a pilot bore or to upsize the borehole and tow in product pipe. 
         [0031]    In the method for making boreholes in accordance with the present invention, a boring machine having a rotary drive system capable of rotating and axially advancing or retracting a downhole tool attached to a drill string is used. The method comprises connecting the first end  18  of the first member  12  to the drill string. The first member  12  may be connected to the drill string by rotating the first member in a first direction to thread the first member  12  to the drill string. The ground engaging member  16  is slid over the second end  18  of the first member  12  so that the non-circular exterior surface  40  of the first member is positioned with the interior non-circular surface  66  of the ground engaging member. The non-circular surfaces  40  and  66  may comprise a geometric profile. For purposes of illustration only, an octagonal profile will be described. The octagonal profiles of the first member and the ground engaging member  16  are aligned before sliding the ground engaging member over the second end  20  of the first member. 
         [0032]    The second member  14  is engaged to the socket  42  of the first member  12  and the second member is oriented, by rotation, such that the non-circular surface  66  of the second member fits within the ground engaging member  16  to pass rotation of the drill string and the first member to the ground engaging member and the second member. The second member  14  may comprise a threaded end portion  46  and the socket  42  may comprise corresponding threads. The method comprises threading the threaded end portion into the socket until the external non-circular surface of the second member is adjacent to the ground engaging member. The second member may then be rotated slightly to align the external non-circular surface  48  with the internal non-circular surface of the ground engaging member. The ground engaging member  16  is then moved axially to substantially cover the external non-circular surface of the second member. The holes  32  and  52  are aligned and the fastener  33  is inserted into the holes to fasten the second member  14  to the ground engaging member  16 . 
         [0033]    As will be appreciated, the joint of the invention is applicable to a variety of applications wherein tools used in horizontal directional drilling are connected to a drill string. Joints in accordance with the invention are particularly useful in coupling drill bits, sonde housings, reamers, back reamers, starter rods, impactors and similar drilling tools to a drill string or together in a manner that facilitates rapid replacement of such components while simultaneously providing joints and couplings with an increased usable lifetime and enhanced reliability. 
         [0034]    Various modifications can be made in the design and operation of the present invention without departing from the spirit thereof. Thus, while the principal preferred construction and modes of operation of the invention have been explained in what is now considered to represent its best embodiments, as herein illustrated and described, it should be understood that the invention may be practiced otherwise than as specifically illustrated and described.