Abstract:
A directional boring head assembly having a directional boring head, with a deflection surface capable of steering the directional boring head, combined with a replaceable cutting member is provided. The position of the cutting member relative to the deflection surface permits the directional boring head to steer the boring machine along the desired path while providing enhanced cutting action adaptable to different soil types. As the boring machine is advanced with rotation, the leading edge of the cutting member contacts only a small portion of the perimeter of the borehole thereby increasing the contact stress between the cutting member and the face of the borehole for more aggressive cutting action in hard ground conditions. Additionally, the directional boring head is provided with a pocket adapted to conform to the cutting member. The pocket engages the cutting member so that the cutting member fits snugly within the directional boring head thereby increasing the stability of the cutting member within the directional boring head. The cutting member may be replaced to simplify maintenance and to accommodate a variety of soil conditions. The directional boring head and the cutting member function together to maximize the cutting and steering capabilities of the directional boring head assembly while maintaining the integrity of the overall structure.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to boring heads, and in particular to directional boring head assemblies for drilling horizontal boreholes underground. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a directional boring head assembly for use with a boring machine capable of directionally drilling horizontal underground boreholes, wherein the boring machine includes a drill string with an end for supporting a directional boring head assembly. The directional boring head assembly comprises a directional boring head and cutting member. The directional boring head has a rear end, a forward portion, and a body portion therebetween. The rear end is releasably connectable to the end of the drill string and the forward portion has a slot therethrough. The cutting member has a planar rear portion, a forward end, and a body portion therebetween. The planar rear portion of the cutting member is insertable into the slot of the directional boring head, and the forward end has a cutting edge. The cutting member is releasably connectable to the directional boring head. The directional boring head is provided with a deflection surface inclined at an angle relative to the longitudinal axis of the directional boring head. A portion of the cutting member extends beyond the forward portion of the directional boring head. 
     The present invention further includes a directional boring head for use with a boring machine capable of directionally drilling horizontal underground boreholes, wherein the boring machine includes a drill string with an end for supporting a boring head. The directional boring head has a rear end, a forward portion, and a body portion therebetween. The rear end is releasably connectable to the end of the drill string. The forward portion has a slot therethrough adapted to receive a releasable cutting member. The directional boring head is provided with a deflection surface inclined at an angle relative to the longitudinal axis of the directional boring head. 
     The present invention further includes a directional boring machine capable of directionally drilling horizontal underground boreholes. The directional boring machine comprises a drill string with an end for supporting a directional boring head assembly, means for intermittently rotating and axially advancing the drill string and a directional boring head assembly. The directional boring head assembly comprises a directional boring head and a cutting member releasably connectable to the directional boring head. The directional boring head has a rear end, a forward portion, and a body portion therebetween. The rear end is releasably connectable to the end of the drill string, and the forward portion has slot therethrough. The cutting member has a planar rear portion insertable into the slot of the directional boring head, and a forward end having a cutting edge. The directional boring head is provided with a deflection surface inclined at an angle relative to the longitudinal axis of the directional boring head, and wherein a portion of the cutting member extends beyond the forward portion of the directional boring head. 
     Finally, the present invention includes a directional boring head assembly for use with a boring machine capable of directionally drilling horizontal underground boreholes, wherein the boring machine includes a drill string with an end for supporting a directional boring head assembly. The directional boring head assembly comprises a directional boring head having a rear end, a forward portion, a body portion therebetween, a forward edge and a single planar cutting blade. The rear end of the directional boring head is releasably connectable to the end of the drill string, and the forward portion defines a deflection surface. The deflection surface is inclined at an angle and terminates at the forward edge. The single planar cutting blade is non-parallel to the longitudinal axis and to the deflection surface of the directional boring head. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevational view of a directional boring machine for drilling a horizontal borehole in the earth. 
     FIG. 2 is an assembled, perspective view of the directional boring head assembly in accordance with the present invention. 
     FIG. 3 is a plan view of the directional boring head shown in FIG.  2 . 
     FIG. 4 is a side elevational view of the directional boring head shown in FIG.  2 . 
     FIG. 5 is a side elevational view of the cutting member shown in FIG.  2 . 
     FIG. 6 shows an exploded, perspective view of the directional boring head assembly of FIG.  2 . 
     FIG. 7 is an inverted exploded, perspective view of the directional boring head assembly shown in FIG.  2 . 
     FIG. 8 is a front end view of the directional boring head assembly of FIG.  2 . 
     FIG. 9 is an alternative embodiment of the directional boring head assembly of the present invention, and shows the cutting member in a position non-perpendicular to the deflection surface of the directional boring head. 
     FIG. 10 is an end view of the directional boring head assembly of FIG.  9 . 
     FIG. 11 is a top view of another embodiment of the directional boring head assembly of the present invention, and shows the cutting member in a position non-parallel to the linear axis of the directional boring head. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Boring machines are used in industry to form boreholes under and around obstacles in the ground. Typically, boring machines are used to form boreholes under roadways to run conduits such as utility lines. Important in the operation of the boring machine is the ability to steer the boring machine along the desired path. The so called “slant-face” technology is often employed to provide boring machines with boring heads capable of steering drilling operations along a desired path by axially advancing the drill string without rotation. 
     There is a continuing need to develop boring heads capable of operating in a variety of soil conditions. The present invention improves flexibility and stability by providing a replaceable cutting member in combination with a slant faced directional boring head. The cutting member provides a forward edge for enhanced cutting and piercing capabilities, and the deflection surface, sometimes referred to as a directional surface, provides directional control and steering capabilities. The replaceable cutting member adds flexibility to the drilling operation by permitting the operator to change the cutting member as needed for variable soil conditions or maintenance. Additionally, the present invention employs a pocket in the directional boring head for holding the cutting member within the directional boring head. The pocket reduces the likelihood of incidents such as the loosening of bolts, and the need for numerous connecting devices, such as high strength bolts, to secure the replaceable cutting member within the directional boring head. These and other advantages of the present invention will be apparent from the following description of the preferred embodiments. 
     Turning now to the drawings in general and to FIG. 1 in particular, shown therein is a boring machine  10  constructed in accordance with the present invention. Preferably, the boring machine  10  generally comprises a frame  12 , a drive mechanism  14  supported on the frame  12 , a drill string  16  and a directional boring head assembly  18 . The drive mechanism  14  may be used to intermittently rotate and axially advance the drill string  16 . The drill string  16  has an end  20  adapted to support a directional boring head assembly  18 , as will be more fully described herein. 
     While the boring machine in FIG. 1 is depicted as a rotary boring machine for drilling underground boreholes, it will be appreciated that the directional boring head assembly may be used in conjunction with a variety of drilling and boring systems. For example, the directional boring head assembly may be used with percussive, rotary, hydraulic, electric, and manual systems, as well as other types of drilling and boring machines. 
     Turning now to FIG. 2, the preferred directional boring head assembly  18  for use with the boring machine  10  is illustrated. The directional boring head assembly  18  generally comprises a directional boring head  26  and a cutting member  28 . 
     Referring now to FIGS. 3 and 4, the directional boring head  26  is shown. The directional boring head  26  is generally cylindrical with a rear end  30 , a forward portion  32  and a body portion  34  therebetween. The rear end  30  of the directional boring head  26  is adapted to be releasably connectable to the end  20  of the drill string  16 . 
     The directional boring head  26  may be provided with a fluid passage  36  continuous with a passage through the drill string. The fluid passage  36  of the directional boring head  26  preferably is parallel to longitudinal axis x—x of the directional boring head  26 . Alternatively, a fluid passage may also be provided that is non-linear and/or non-parallel to the longitudinal x—x axis of the directional boring head. 
     The fluid passage may be used to permit drilling fluids to be passed from the boring machine, through the directional boring head assembly, and into the borehole. Drilling fluids may then be used to enhance the boring operation by cooling the directional boring head assembly and moistening the earth surrounding the boring apparatus. Typically, the moisture enables the directional boring head assembly to pack the soil against the walls of the borehole thereby assisting the directional boring head assembly in forming the borehole. 
     It may be desirable to include a check valve  38  to control the release of boring fluids from the directional boring head  26 . The check valve  38  may also be used to block the back flow of contaminants into the directional boring head  26 , particularly when drilling is not currently ongoing. 
     The directional boring head  26  may also be provided with gripping surfaces  39  preferably located on the body portion  34  of the directional boring head. The gripping surfaces  39  may be adapted to receive a tool, such as a pipe wrench, which may be used to rotate the directional boring head  26  for attachment to or removal from the end  20  of the drill string  16 . 
     Referring still to FIGS. 3 and 4, the forward portion  32  of the directional boring head  26  defines a deflection surface  40  extending from the rear end  30  to the forward edge  42  of the directional boring head. As best seen in FIG. 4, the deflection surface  40  of the directional boring head  26  tapers downward from the rear end  30  and preferably terminates at the forward edge  42  of the directional boring head  26 . That is, the deflection surface  40  is inclined at an angle relative to the longitudinal axis x—x of the directional boring head  26 . 
     It should be noted that the deflection surface  40  is depicted as being substantially flat. However, it will be appreciated that the deflection surface  40  may be made convex or concave with a smooth, textured, or angled surface in accordance with the present invention. In other words, any configuration is sufficient which will deflect the directional boring head when the drill string is advanced in accordance with known procedures. 
     With continuing reference to FIGS. 3 and 4, the forward portion  32  of the directional boring head  26  is provided with a longitudinal slot  44 . The longitudinal slot  44  preferably has a size and shape adapted to engagingly receive and support the cutting member  28 , as will be more specifically described herein. 
     In the preferred embodiment, the longitudinal slot  44  forms a pocket  43  in the directional boring head  26 . The pocket  43  is a three dimensional polygonal cavity having a top wall  45 , a back wall  46  and two sidewalls  47 . Preferably, the top wall  45 , back wall  46  and two sidewalls  47  of the pocket  43  are closed and the front and bottom of the pocket  43  remain open to receive the cutting member  28 . While the transverse slot is shown in FIGS. 3 and 4 as forming a pocket, it should be understood that the longitudinal slot may only have two side walls and a back wall. 
     The longitudinal slot  44  preferably extends a distance from the forward edge  42  toward the rear end  30  of the directional boring head  26 , and a distance from the bottom  48  of the directional boring head  26  towards the fluid passage  36 . As best seen in FIG. 3, the longitudinal slot  44  has a width and intersects a portion of the deflection surface  40 , thereby dividing the forward edge  42  of the directional boring head  26  into two portions  50 . 
     Referring now to FIG. 5, a preferred cutting member  28  is shown. The cutting member  28  is generally polygonal and has a planar rear portion  52 , a forward end  54  and a body portion  56  therebetween. The forward end  54  of the cutting member  28  preferably is provided with a cutting edge  58  having a leading tooth  64  followed by a plurality of reclining steps  66 . In the preferred embodiment, the cutting edge  58  is asymmetrical with the plurality of reclining steps  66  tapering from the leading tooth  64  back toward the planar rear portion  52  of the cutting member  28 . 
     The cutting edge  58  may be provided with a variety of edge patterns to enhance the cutting and/or piercing action of the cutting member  28 , including a serrated, smooth, or jagged edge. It should also be understood that the cutting edge  58  of the cutting member  28  is positionable relative to the forward edge  42  of the directional boring head  26 . For example, at least a portion of the cutting edge  58  of the cutting member  28  may extend a distance beyond the forward edge  42  or be positioned behind the forward edge  42  of the directional boring head  26  and/or intersect at least a portion of the deflection surface  40  of the directional boring head . 
     The cutting member  28  may be provided with hard surface protection, such as an abrasion or wear resistant material, to increase the durability of the cutting member. The use of hard surface protection, such as tungsten carbide and weld beads, are described in U.S. Pat. No. 5,779,740, the entire contents of which are incorporated herein by reference. It should be understood that other materials for providing wear resistance for the cutting member may be used such as metallurgical case hardening or sintered diamond buttons. 
     Referring now to FIGS. 2,  6  and  7 , the placement of the cutting member  28  within the pocket  43  of the directional boring head  26  helps to secure the cutting member within the directional boring head. The cutting member  28  is sized and shaped to fit snugly in the pocket  43  and extend through the longitudinal slot  44 . 
     The pocket  43  formed by the longitudinal slot  44  within the directional boring head  26  helps to retain the cutting member  28  within the directional boring head during operation. The planar rear portion  52  of the cutting member  28  is positionable against the top wall  45 , back wall  46  and two sidewalls  47  of the pocket  43 . The multi-surface support provided by the pocket  43  reduces the likelihood that the cutting member  28  will detach from the directional boring head  26  during operation. The pocket further enhances the boring operation by reducing the number of fasteners required to secure the cutting member within the directional boring head. 
     It should be further understood that while the pocket is shown as a three dimensional rectangular slot, the pocket may be provided with alternative geometries and cavities adapted to receive a cutting member with a corresponding configuration. For example, the cutting member may have portions extending from the rear end of the cutting member which are disposable within a pocket having corresponding cavities therein. These configurations may add to the gripping engagement between the cutting member and the directional boring head thereby further reducing the number of fasteners required to secure the cutting member within the directional boring head. 
     Preferably, the cutting member  28  is disposed within the longitudinal slot  44  so that the forward end  54  of the cutting member  28  is positioned near the forward edge  42  of the directional boring head  26 . It is often desirable to have the forward end  54  of the cutting member  28  extend a distance beyond the forward portion  32  of the directional boring head  26  so that the cutting member  28  acts as the initial contact point with the borehole during the drilling operation. That is, the cutting member  28  can extend upwardly beyond the deflection surface  40 , extend axially beyond the forward edge  42 , or otherwise protrude outside of the pocket  43  in any direction above, below or in advance of the directional boring head  26 . 
     Now it should be appreciated that, while a single longitudinal slot  44  is depicted with a single cutting member  28  therein, more than one cutting member may be inserted into a single longitudinal slot. Alternatively, more than one longitudinal slot  44  may be provided so that one or more cutting members  28  may be disposed in each longitudinal slot  44 . 
     It should also be appreciated that while the shape of the cutting member is generally polygonal and planar, the cutting member may be of any shape that provides the directional boring head with cutting ability. The cutting member may be formed integrally with the directional boring head, or shaped to fit within the longitudinal slot and/or pocket. A variety of cutting blades may be interchanged and used with the directional boring head. Similarly, the longitudinal slot may be of any dimension and at any angle to house the cutting member in the desired orientation or location. 
     Referring now to FIGS. 6 and 7, the cutting member  28  may be releasably mounted to the directional boring head  26  by means of bolts  59 . Preferably, the bolts  59  are insertable through holes  60  in the directional boring head  26  and holes  62  in the cutting member  28  and threadably connectable to the directional boring head  26 . Alternatively, the bolts  59  may be disposed through the holes in the directional boring head and secured therein via means such as pins or nuts. 
     The holes  60  in the directional boring head  26  intersect the longitudinal slot  44  and preferably are aligned with the holes  62  in the cutting member  28  so that the cutting member  28  may be secured within the directional boring head  26  in the desired position. More than one bolt  59  may be used to secure the cutting member  28  in place thereby further establishing the desired position of the cutting member  28  within the directional boring head  26 . When a connecting device such as a bolt threadably connected to the directional boring head is used, the bolt may be tightened so that the forward portions of the directional boring head are drawn together thereby clamping the cutting member therebetween. 
     It will be understood that various methods and devices for connecting the cutting member  28  to the directional boring head  26  may be employed including welds, glue, screws, pins, rivets, bonds, clamps, friction fit, set screws, pins, shims, adhesives, nuts and bolts, or welds. However, it will be appreciated that in some instances the cutting member  28  may be formed integrally with the directional boring head  26 . 
     Referring now to FIGS. 2 and 8, the cutting member  28  is shown in a generally vertical orientation within the directional boring head  26 . The cutting member  28  is positioned within the longitudinal slot  44  of the directional boring head  26  so that the cutting member bisects the forward portion  32  of the directional boring head  26  and forms two equal front portions  50 . 
     As best seen in FIG. 2, the cutting member  28  extends a distance beyond the deflection surface  40  at an angle perpendicular to the deflection surface  40 . 
     Turning now to FIGS. 9 and 10, a second embodiment of the directional boring head assembly  18   a  is shown. The directional boring head assembly  18   a  comprises a directional boring head  26   a , a cutting member  28   a , and a plurality of carbide buttons  70 . 
     The second embodiment of the directional boring head assembly  18   a  is similar to the first embodiment of the directional boring head assembly  18  heretofore described, except that the position of the cutting member  28   a  is rotated about the longitudinal axis x—x of the directional boring head  26   a  so that the cutting member  28   a  is no longer perpendicular to the deflection surface  40   a , as best seen in FIG.  10 . In other words, the cutting member  28   a  is rotated counterclockwise 45 degrees about the longitudinal axis x—x defined by the directional boring head  26  and positioned in the directional boring head  26  at an angle non-perpendicular to the deflection surface  40   a.    
     The non-perpendicular angle of the cutting member  28   a  shifts the position that the directional boring head contacts the borehole during the boring operation so that a larger portion of the outer surface of the directional boring head contacts the borehole. The increase in the amount of surface area of the directional boring head that contacts the borehole diffuses the contact force over a larger portion of the directional boring head thereby increasing wear resistance. 
     The directional boring head  26   a  may be provided with means for providing wear resistance for the directional boring head  26   a , such as plurality of carbide wear buttons  70 . The carbide wear buttons  70  are disposed on the body portion  34   a  adjacent the deflection surface  40 . The use of hard surface protection, such as carbide wear buttons, are described in U.S. Pat. No. 5,779,740, previously incorporated herein. It should be understood that other methods of providing wear resistance for the directional boring head may be used such as metallurgical case hardening or hard surface welding material. 
     Referring now to FIG. 11, a third embodiment of the directional boring head assembly  18   b  is shown. The directional boring head assembly  18   b  comprises a directional boring head  26   b , and a single planar cutting blade  28   b.    
     The third embodiment of the directional boring head assembly  18   b  is similar to the first embodiment of the directional boring head assembly  18  heretofore described, except that the position of the single planar cutting blade  28   b  is non-parallel to the longitudinal axis x—x of the directional boring head  26   b , as best seen in FIG.  11 . 
     It should be noted that, the cutting member depicted in FIG. 11 is a single planar cutting blade  28   b . However, it will be appreciated that a multi-blade cutting member may also be used with the present invention. 
     Now it will be appreciated that the present invention provides an improved directional boring head assembly. A boring head using the “slant face” directional technology is advantageously combined with a replaceable cutting member. The directional boring head assembly enhances the advantages of a releasable cutting member by permitting substitution of different cutting members for various types of soil. The flexibility of cutting members is particularly necessary where more than one type of soil is encountered. The advantages of the releasable cutting member may be combined with the advantages of the deflection surface of the directional boring head which provides directional control. The position of the cutting member may be placed at an angle to the deflection surface thereby preserving the directional capabilities of the deflection surface while enhancing the cutting and drilling capabilities of the cutting member. Together, the directional control of the directional boring head combined with the drilling action provided by the cutting member enhance the borehole operation. 
     Changes may be made in the combination and arrangements of the various parts, elements, steps and procedures described herein without departing from the spirit and scope of the invention as defined in the following claims.