Patent Publication Number: US-6655476-B2

Title: Earth boring bit

Description:
This is a continuation of application Ser. No. 09/791,235, filed Feb. 23, 2001, now U.S. Pat. No. 6,533,048. 
    
    
     TECHNICAL FIELD AND BACKGROUND OF THE INVENTION 
     This invention relates to an earth boring bit for boring very precise circular holes in the earth. Such holes include, but are not limited to, holes for foundation piers, footings and the like. Prior art auger-type machines are typically used to drill holes in the earth, and present a number of disadvantages. Specifically, the auger transports the earth upwardly and spills it on the ground around the hole. In many instances, the earth around the hole may fall back into the hole when the auger is removed, or may fall into nearby footings or foundation piers. In addition, boring a hole to a precise depth with an auger is difficult, since the auger provides no visual cues as to the distance of the tip of the auger below the earth. The flights of the auger must be relatively far apart to accommodate the earth being removed from the hole. This reduces the precision with which the hole is bored, and increases the amount of earth which falls from the auger when the auger is removed from the hole. Finally, even if the earth removed from the hole by the auger does not fall back into the hole, the earth is piled around the hole and must be removed by a completely separate operation, generally by hand by a laborer who uses a shovel. 
     The invention of the present application addresses the problems presented by prior art augers by providing a unique, rotating earth boring bit. The earth boring bit includes a cylindrical drum having an open lower end to which a plate is attached. Unique cutting assemblies are positioned on the plate. The earth boring bit is operatively connected to a hydraulic motor on a mobile machine such as a skid steer backhoe. Powered by the hydraulic motor of the mobile machine, the earth boring bit rotates, thereby causing the cutting assemblies to bore a hole into the earth by slicing and upturning the earth, and directing the upturned earth into the drum. The upturned earth is maintained within the drum until the boring process is completed, and is then removed from the drum after the earth boring bit has been moved to a location away from the freshly-bored hole. The unique structure of the present invention thus overcomes the disadvantages of prior art augers by providing an earth boring bit which is capable of boring a hole which has sidewalls that are perpendicular to the bottom of the hole, and which is free of upturned earth. The holes bored by the earth boring bit of the present invention are so precise that multiple holes may be bored in close proximity to one another without jeopardizing the structure of a single hole. 
     SUMMARY OF THE INVENTION 
     Therefore, it is an object of the invention to provide an earth boring bit which bores a hole of a precise depth and in a precise location. 
     It is another object of the invention to provide an earth boring bit that does not spill the earth from the bored hole onto the ground around and near the hole as the hole is being bored. 
     It is yet another object of the invention to provide an earth boring bit which includes means for transporting the earth removed from the bored hole to a predetermined location away from the hole for disposal. 
     It is another object of the invention to provide an earth boring bit which forms a clean, uniformly-sized hole having a relatively flat bottom and relatively perpendicular sides. 
     It is another object of the invention to provide an earth boring bit which can be operated from a tractor, backhoe, or other mobile machines. 
     These and other embodiments of the invention are achieved in the preferred embodiments disclosed below by providing an earth boring bit for boring a hole having a predetermined depth into the earth. The earth boring bit includes a cylindrical drum for being mounted for rotation on the end of a boom of a mobile machine and connected to and rotated by a power supply mounted on the boom. The drum includes an exterior for defining the diameter of the hole being bored and an interior adapted for receiving upturned earth therein as the hole is being bored. A plate is carried by the drum adjacent a lower end thereof for movement between a closed position for cooperating with the interior of the drum for retaining the upturned earth therein and an open position for dispensing the upturned earth out of the interior of the drum at a predetermined location away from the hole being bored. A cutting member is carried on the plate for cutting the earth in a thin, progressive slice and directing the earth into the drum, thereby boring the hole into the earth. 
     According to one preferred embodiment of the invention, the cutting member includes an opening extending through the plate and defined by adjacent teeth projecting outwardly away from the plate for cutting the earth into the progressive slice as the boring assembly rotates. 
     According to another preferred embodiment of the invention, the earth boring bit includes a pilot bit centrally positioned on and extending outwardly away from the plate for making a pilot hole in the earth for centering the earth boring bit within the hole as the earth boring bit rotates. 
     According to yet another preferred embodiment of the invention, the earth boring bit includes a spring-loaded handle engaging the plate for moving the plate between said open and closed positions. 
     According to yet another preferred embodiment of the invention, the handle includes an elongate rod having first and second ends. The rod is positioned within and extends through the interior of the drum. A latch is connected to the second end and cooperates with a complementary keyhole defined in and extending through the plate. The latch has a longitudinal axis positioned perpendicular to the longitudinal axis of the keyhole for maintaining the plate in its closed position. The latch is positioned parallel to the longitudinal axis of the keyhole for moving the plate into the open position. A handle is connected to the first end of the rod and cooperates therewith for selectively moving the latch between the perpendicular and parallel positions, thereby moving the plate between the closed and open positions, respectively. 
     According to yet another preferred embodiment of the invention, the earth boring bit includes two cutting members positioned in radial opposition to one another. The teeth on each of the cutting members collectively define a cutting edge extending perpendicularly from the pilot bit, thereby creating a cutting edge having an effective diameter equal to the diameter of the drum. 
     According to yet another preferred embodiment of the invention, the earth boring bit includes two opposing interior cutting members and two opposing exterior cutting members. 
     According to yet another preferred embodiment of the invention, each of the interior cutting members is positioned adjacent to the pilot bit, and each of the exterior cutting members is positioned adjacent to an outer edge of the plate. 
     According to yet another preferred embodiment of the invention, the teeth on each of the exterior cutting members form a cutting edge extending beyond said outer edge of the plate and having an effective diameter extending beyond the diameter of the plate for reducing friction on the exterior of the drum as the earth boring bit rotates. 
     According to yet another preferred embodiment of the invention, the teeth on each of the interior and exterior cutting members collectively define a cutting edge extending perpendicularly from the pilot bit for cutting a progressive slice of earth having a diameter which extends across the diameter of the plate. 
     According to yet another preferred embodiment of the invention, the plate and drum are pivotally connected together along common joint edges by a hinge element for permitting the plate to move between the open and closed positions. 
     According to yet another preferred embodiment of the invention, the earth boring bit includes a drive shaft operatively connected to the power supply mounted on the boom, wherein the drum and plate are coaxially mounted on said drive shaft for rotation therewith. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Some of the objects of the invention have been set forth above. Other objects and advantages of the invention will appear as the invention proceeds when taken in conjunction with the following drawings, in which: 
     FIG. 1 is a side elevation of an earth boring bit according to the present invention; 
     FIG. 2 is a cut-away side elevation of the earth boring bit shown in FIG. 1 showing the drive mechanism of the machine; 
     FIG. 3 is a side elevation of the earth boring bit showing the bottom plate of the machine in an open position; 
     FIG. 4 is a perspective view of the earth boring bit showing the bottom of the earth boring bit; 
     FIG. 5 is a cut-away side elevation of the earth boring bit showing the handle assembly of the machine; 
     FIG. 6 is an environmental perspective view of the earth boring bit with the bottom plate in a closed position; 
     FIG. 7 an environmental perspective view of the earth boring bit showing upturned earth being removed from the machine after a hole has been bored; and 
     FIG. 8 is an environmental perspective view of a series of holes created by the earth boring bit of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT AND BEST MODE 
     Referring now specifically to the drawings, an earth boring bit according to the present invention is illustrated in FIG.  1  and shown generally at reference numeral  10 . The earth boring bit  10  includes a cylindrical drum  20 , which has upper and lower open ends  21  and  22 , respectively, and interior and exterior sidewalls  23  and  24  (interior sidewall  23  is shown in FIG.  2 ). While the drum  20  may have any diameter, the drum  20  preferably has a diameter of between 12 inches and 36 inches. A bottom plate  30  upon which a cutting assembly  40  is carried is attached to the interior of the drum  20  adjacent lower open end  22 . The plate  30  is shown in FIG. 1 in a closed position. As discussed more fully below with reference to FIGS. 3 and 4, the cutting assembly  40  is used to cut progressive slices of earth as the hole is being bored. The upturned earth is retained within the drum  20  by the plate  30  until the upturned earth is removed from the drum  20  at a location away from the hole. As is shown in FIG. 1, the earth boring bit  10  is rotated by a drive mechanism  50 , which is concentrically positioned within the drum  20 , and is operatively connected to the plate  30 . A handle assembly  60  likewise extends through the drum  20  and engages the plate  30  for moving the plate  30  between the closed position and an open position. See FIG.  3 . As discussed in detail below with reference to FIGS. 6-8, the earth boring bit  10  is preferably operatively connected to the boom of a moving machine which is powered by a hydraulic motor. 
     Referring now to FIG. 2, the drive mechanism  50  is shown. The drive mechanism  50  includes a drive shaft  51  having a first end  52  affixed to a drive shaft receiver  53 , and a second end  54  to which a cap plate  55  is attached. The drive shaft  51  is mounted on a cross brace  56  which is in turn welded to the interior sidewalls  23  on the upper end  21  of the drum  20 . Mounting the drive shaft  51  in this manner permits the drive assembly  50  to rotate the drum  20  in unison with the rotation of the drive shaft  51 . A pair of support flanges  57 A and  57 B are attached to the drive shaft  51  and cross brace  56 , and stabilize the drive shaft  51  against the cross brace  56 . While the upper end  21  of the drum  20  is open for permitting the interior of the drum  20  to be easily viewed, the drum  20  may alternatively include a top cover (not shown) which covers approximately three-fourths of the upper opening  21 , thereby leaving approximately one-fourth of the upper opening  21  uncovered for permitting the interior of the drum  20  to be viewed by an individual operating the earth boring bit  10 . 
     As is shown in FIG. 2, the plate  30  includes a center drive plate shaft  31  which is centrally positioned on the plate  30 . A cap plate  32  is attached to an upper end  33  of the shaft  31  and engages the cap plate  55  on the second end  54  of the drive shaft  51  when the plate  30  is in the closed position. The shaft  31  is preferably formed from steel, and supports and stabilizes the plate  30 . 
     Referring now to FIG. 3, the plate  30  is shown in the open position. The cutting assembly  40  is carried by the plate  30  and includes a pilot bit  41 , and inner and outer cutting members  42 A,  42 B, and  43 A,  43 B, respectively. The pilot bit  41  is affixed to an extension  31 A of the drive plate shaft  31  for making a pilot hole in the earth to center and guide the earth boring bit  10  as the boring process begins. 
     Referring now to FIG. 4, each inner and outer cutting member  42 A,  42 B,  43 A, and  43 B, includes a respective opening  44 A,  44 B,  44 C and  44 D which is defined by and extends through the plate  30 . The openings  44 A,  44 B,  44 C and  44 D include respective edges  45 A,  45 B,  45 C and  45 D to which respective downwardly-projecting cutting plates  46 A,  46 B,  46 C and  46 D are attached. Each cutting plate  46 A,  46 B,  46 C and  46 D is preferably formed from steel, and includes a row of cutting teeth  47 A,  47 B,  47 C and  47 D, respectively. 
     As discussed more fully in reference to FIGS. 6-8 below, the cutting teeth  47 A,  47 B,  47 C and  47 D cut into the earth in a progressive slice as the earth boring bit  10  rotates. Although any number of teeth may be used, each row of cutting teeth  47 A,  47 B,  47 C and  47 D preferably includes three teeth. The teeth  47 A,  47 B,  47 C and  47 D cooperate with the respective cutting plates  46 A,  46 B,  46 C and  46 D to drive the upturned earth through the respective openings  44 A,  44 B,  44 C and  44 D into the interior of the drum  20  as the earth boring bit  10  rotates. The earth is then retained until the plate  30  is moved into the open position. As is shown in FIG. 4, the plate  30  is moved between the open and closed positions using a hinge  35 , which preferably includes a rolled steel hinge pin which cooperates with a complementary hinge plate. 
     Each row of cutting teeth  47 A,  47 B,  47 C and  47 D is preferably attached to the corresponding cutting plate  46 A,  46 B,  46 C or  46 D at least a 35 degree angle “θ” from a bottom surface  36  of the plate  30 . As shown in FIG. 4, the inner cutting members  42 A and  42 B are positioned adjacent the pilot bit  41  and opposite one another so that the respective rows of teeth  47 A and  47 B extend outwardly away from and are positioned perpendicular to the plate shaft extension  31 A and bit  41 . The outer cutting members  43 A and  43 B are positioned adjacent an outer edge  37  of the plate  30  and opposite one another so that the respective rows of teeth  47 C and  47 D likewise extend outwardly away from and are positioned perpendicular to the plate shaft extension  31 A and bit  41 . Furthermore, each outer cutting member  43 A and  43 B is positioned on the plate  30  so that outer end  49 A and  49 B of the respective cutting members  43 A and  43 B each extend beyond the outer edge  37  of the plate  30 . Positioning the outer cutting members  43 A and  43 B on the plate  30  in this manner causes the outer cutting members  43 A and  43 B to cut slices of earth which form a hole having a diameter which is slightly larger than diameter of the exterior sidewalls  24  of the drum  20 . This reduces friction on the exterior sidewalls  24  during operation, thus extending the life of the drum  20  and earth boring bit  10 . When in use, the inner and outer cutting members  42 A,  42 B and  43 A,  43 B collectively cut circular slices of earth having a diameter slightly greater than the diameter of the plate  30 . 
     Referring now to FIG. 5, the earth boring bit  10  is shown with the outer cutting member  43 B removed to show the handle assembly  60 . The handle assembly  60  includes an elongate rod  61  having first and second ends  62  and  63 . The rod  61  preferably has a diameter of ¾ inch and is positioned within and extends through the interior of the drum  20  adjacent the interior sidewall  23 . The rod  61  is received and held by a tube support  66  which is attache to the interior sidewall  23  of the drum  20 . The tube support provides enhanced stability and support to the rod  61 . A latch handle  64  is attached to the first end  62  of the rod  61 , and is interconnected to the support flange  57 B by a spring  65 . Complementary zinc nuts and bolts  65 A and  65 B connect the spring  65  to the flange  57 B and the handle  64 . The spring  65  is preferably a compression spring, and cooperates with the latch handle  64  to move the handle assembly  60  between, and maintain the handle assembly  60  in, the open and closed positions. 
     The handle assembly  60  also includes a latch plate  67 , which is attached to the second end  63  of the rod  61 . The latch plate  66  is shown in FIGS. 4 and 5 maintaining the plate  30  in the closed position. As is shown in FIG. 4, the plate  30  includes an opening  68  which has a shape complementary to the shape of the latch plate  67 . Referring again to FIG. 5, the second end  63  of the rod  61  and the latch plate  67  both extend through the opening  68 . When the plate  30  is in the closed position, latch plate  67  is positioned so that its longitudinal axis “L P ” is generally perpendicular to the longitudinal axis “L O ” of the opening  68 . To move the handle assembly  60  to the open position, the latch handle  64  is rotated 90 degrees against the force of the spring  65 , which rotates the rod  61  around its longitudinal axis. This in turn causes the latch plate  67  to rotate until its longitudinal axis “L P ” is in alignment with the longitudinal axis “L O ” of the opening  68 . This permits the plate  30  to move into the open position shown in FIG. 3 using the hinge  35 . 
     Referring now to FIGS. 6,  7  and  8 , the earth boring bit  10  is shown being used to bore a hole into the earth. The earth boring bit  10  is shown in FIGS. 6,  7  and  8  connected to a hydraulic motor “M” which is connected to the boom “B” of a mobile machine “MM”. To use the earth boring bit  10  to bore a hole, the earth boring bit  10  is centered over the site where the hole is to bored and is lowered into position in the direction “D” shown. The pilot bit  41  maintains the machine  10  in position while the hydraulic motor “M” is actuated, which in turn causes the drive assembly  50  to rotate the drum  20  and plate  30 . The overall design of the earth boring bit and the angle of the teeth on the inner and outer cutting members  42 A,  42 B and  43 A,  43 B causes the earth boring bit  10  to begin cutting away a slice of the earth “E” as the earth boring bit  10  rotates. As the rows of teeth  47 A,  47 B,  47 C and  47 D on the cutting members  42 A,  42 B,  43 A and  43 B continue to cut into the earth “E”, the upturned earth “E” is pushed into the interior of the drum  20 . The depth of the hole being bored can accurately be determined by observing that portion of the drum  20  which is still above the ground. The drum  20  may alternatively include markings on the exterior sidewall  24  for further facilitating the accuracy of the cut (not shown). Furthermore, the earth boring bit  10  can be withdrawn from the hole during the boring process to check the depth of the hole. Cuts up to 12 inches can be made in a single operation, based upon soil type and density. As discussed above, the plate  30  cooperates with the drum  20  to prevent earth “E” from falling back into the hole as the earth boring bit  10  is removed therefrom. 
     Referring now to FIG. 7, when the drum  20  has been filled with earth, the earth boring bit  10  is lifted from the hole “H”. The earth boring bit  10  is then moved to a preselected location away from the hole “H” so that the upturned earth “E” can be emptied out of the drum  20 . The earth boring bit  10  is moved by swinging the boom “B” upon which the earth boring bit  10  is mounted away from the hole “H”. If the earth boring bit  10  is attached to a tractor, skid steer backhoe, or other mobile machine having a stationary boom “B”, the earth boring bit  10  must be moved away from the hole “H” by moving the entire mobile machine to the preselected location. 
     To remove the earth from the drum  20 , the latch handle  64  is turned so that the longitudinal axis “L P ” of the latch plate  67  is alignment with the longitudinal axis “L O ” of the opening, which in turn causes the plate  30  to fall open. The plate  30  may be moved into the open position in a controlled manner by maintaining the plate  30  just slightly above ground level when the handle assembly  60  is unlatched so that the pilot bit  41  and the side edge  37  of the plate  30  touches the ground, and then slowing lifting the earth boring bit  10  to allow the plate  30  to swing open gradually. Once all of the earth has fallen out of the drum  20 , the plate  30  can be returned to the closed position. This is be done by lowering the earth boring bit  10  until the bottom of the plate  30  is resting on the ground, so that it is necessary only to insure that the latch plate  67  is properly positioned in the opening  68  in the plate  30 . The handle  64  is then manually turned, thereby rotating the rod  61  and latch plate  67  into the closed position. In an alternative embodiment of the invention, the spring  65  attached to the latch handle  64  automatically rotates the rod  61  and latch plate  67  into the closed position (Not shown). 
     Referring now to FIG. 8, each hole “H” formed by the earth boring bit  10  has smooth, even and uniform sides “S” which are perpendicular to the bottom “B” of the hole “H”. The bottom “B” of the hole “H” is flat, and has a small pilot hole “H pilot ” in its center about which shallow concentric grooves “G” have been formed by the cutting teeth  42 A,  42 B,  43 A and  43 B (not shown). The hole formation process is so precise that the each of the holes “H” may be formed only several inches apart without causing any damage to the other already-formed holes. 
     The depth of holes bored with the earth boring bit  10  is limited only by the length of the drive shaft  31 . Although the drive shaft  31  may be of any length, a preferred length is 56 inches. Therefore, a hole “H” having a depth of approximately 56 inches can be formed by boring the hole “H” in several stages and emptying the drum  20  as required. 
     An earth boring bit is described above. Various details of the invention may be changed without departing from its scope. Furthermore, the foregoing description of the preferred embodiment of the invention and the best mode for practicing the invention are provided for the purpose of illustration only and not for the purpose of limitation—the invention being defined by the claims.