Abstract:
An apparatus for drilling a manhole includes a drill comprising a first motor and a drill bit. A rail extends longitudinally away from an exterior surface of the manhole. A carriage is movably engaged with the rail and is coupled to the drill. A mounting device supports the rail on an exterior of the manhole. The mounting device comprises features to transfer axial loading on the drill bit to the manhole. A method for drilling an opening in a manhole includes suspending a drill from a rail coupled to an exterior of the manhole. The rail extends laterally outwardly from the manhole. A drill bit forming part of the drill is rotated while moving the drill longitudinally along the rail toward the manhole. Axial reactive force generated by the drill is transferred to the manhole.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    Priority is claimed from U.S. Provisional Application No. 62/104,881 filed on Jan. 19, 2015. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not Applicable. 
       NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT 
       [0003]    Not Applicable. 
       BACKGROUND 
       [0004]    This disclosure is related to the field of utility (e.g., sewage) access shafts, more commonly known as “manholes.” More particularly, the disclosure relates to methods and apparatus for drilling ports in a side wall of a manhole to enable sealing engagement of an additional utility conduit with a manhole. 
         [0005]    Utility access shafts or “manholes” known in the art include cast concrete, substantially cylindrical conduits. The conduit is typically cast so as to be closed at one longitudinal end, and is open at the other longitudinal end. The conduit may be disposed in a hole from which soil has been removed for the purpose of placement of the conduit. The open end of the conduit may be disposed approximately at ground level and may be covered by a removable grating, plate or cover. The wall of the conduit may have cast therein one or more substantially circular openings into which utility lines, such as sewage pipes are sealingly connected. Sealing connection may include an elastomer sleeve which may be retained in one of the circular openings using an internally expanding retainer band. 
         [0006]    It is known in the art that existing access shafts may require modification to connect additional utility conduits thereto after the shaft has been initially installed in the ground. Modification may require the creation of additional holes in the side wall of the access shaft for sealed connection of one or more additional utility conduits. It is known in the art to create such additional holes by using hand tools and a hammer. Such methods have more recently been banned by regulatory agencies because of the risk of brittle fracture of parts of the access shaft distal from the hammered-out hole, with associated risk of leakage or access shaft failure. 
         [0007]    It is also known in the art to use a drill to create a substantially circular pattern of small holes where the one or more additional holes are to be located. After the full circular pattern is drilled, the remaining concrete inside the pattern may be removed such as by hammering. The hole thus created requires extensive finishing work to create a smooth, substantially round surface for sealing engagement of a utility conduit therein. 
         [0008]    There exists a need for more efficient methods and apparatus for creating holes in access shafts for sealed connection of utility conduits or pipes thereto. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  shows a top view of a support plate for a core drilling apparatus according to the present disclosure. 
           [0010]      FIG. 2  shows an oblique view of the support plate shown in  FIG. 1 . 
           [0011]      FIG. 3  shows an end view of the support plate. 
           [0012]      FIG. 4  shows a side view of the support plate. 
           [0013]      FIG. 5  shows a top plan view of an example embodiment of a core drilling apparatus according to the present disclosure. 
           [0014]      FIG. 6  shows an oblique view of the example embodiment of an apparatus. 
           [0015]      FIG. 7  shows an end view of the example embodiment of an apparatus. 
           [0016]      FIG. 8  shows a side view of the example embodiment of an apparatus. 
           [0017]      FIGS. 9 through 12  show, respectively, a top view, an oblique view, and end view and a side view of a mounting rail assembly for the drill motor, drill bit and movable carriage shown in  FIGS. 5 through 8 . 
           [0018]      FIGS. 13 through 16  show, respectively, a top view, an oblique view, and end view and a side view of a wheel assembly that may be used in some embodiments to enable ease of movement of the example apparatus. 
           [0019]      FIG. 17  shows an example apparatus mounted to a manhole to illustrate installation and operation of the apparatus. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]      FIG. 1  shows a top view of a mounting plate  10  that may be used in some embodiments to position a drill ( FIGS. 4 through 8 ) on an exterior surface of a manhole (not shown in  FIG. 1 , i.e., an access and connection shaft for underground utility lines such as sewage pipes). The mounting plate  10  may be shaped to have mounting surfaces  11  having a radius of curvature substantially the same as an external radius of curvature of the manhole. When the mounting plate  10  is affixed to a manhole, the mounting surfaces  11  generally are in contact with an exterior of the manhole. A base plate  12  may be shaped to conform to a base (not shown) of the manhole. The base (not shown) may be in the form of a flange having a larger external diameter than a shaft portion of the manhole. The base plate  12  may be affixed to or integrally formed with the mounting surfaces  11 . When the mounting plate  10  is affixed to a manhole, the base plate  12  may rest on the base (not shown) to support vertical load of the mounting plate  10  and the drill ( FIGS. 4 through 8 ). 
         [0021]      FIG. 2  shows an oblique view of the mounting plate  10 , wherein the curvature of the mounting surfaces  11  may be more clearly observed. An opening  10 A may be disposed circumferentially between the mounting surfaces  11 . The opening  10 A may be used to affix the drill ( FIGS. 5 through 8 ) and allow passage of a drill bit ( FIGS. 5 through 8 ) through the mounting plate  12  to enable drilling a side wall of the manhole. In the present example embodiment, the opening  10 A may include perforated edges  11 A such that the drill ( FIGS. 5 through 8 ) may be affixed to the mounting plate  10  such as by bolting. The present example perforated edges  11 A may include holes substantially along an entire vertical dimension thereof, such that the drill ( FIGS. 5 through 8 ) may be mounted at a selected vertical position along the mounting plate  10 . Such arrangement may enable positioning the drill at various vertical positions along the manhole whereby the vertical or longitudinal position of the hole may be selected at any position within the length range of the perforated edges  11 A. An uppermost end of the perforated edges  11 A may be connected to each other by a connector bar  11 B. The lowermost end of the perforated edges  11 A may be formed integrally with or may be coupled to the base plate  12 . In combination, the mounting surfaces  11 , the perforated edges  11 A, the connector bar  11 B and the base plate  12  may form a single, rigid unit as the mounting plate  10 . As explained above the foregoing components of the mounting plate  10  may be separate and connected using connectors such as bolts, may be welded together, or may be integrally formed from a single piece of material, e.g., steel plate. 
         [0022]      FIG. 3  shows an end view of the mounting plate  10  wherein the perforated edges  11 A and the opening  10 A may be more clearly observed. A side view of the mounting plate  10  is shown in  FIG. 4  wherein the thickness or depth profile of the mounting plate  10  may be observed. 
         [0023]      FIGS. 5 through 8  show various views of an example embodiment of a drill  15 . Referring first to  FIG. 5  which is a top view of the drill  15 , the drill  15  may be movably affixed to a drill mounting plate (see  FIGS. 9 through 12 ) by a rail  16 . The rail  16  may be coupled to the drill mounting plate ( FIGS. 9 through 12 , e.g., by welding). The drill  15  may comprise a motor  18  rotationally coupled to a drill bit  14 . The motor  18  may be, for example, an electric motor, pneumatic motor or hydraulic motor. The type of motor is not intended to limit the scope of the present disclosure. The drill bit  14  may be an annular bit, e.g., a coring bit. In the present example, a cutting surface of the drill bit  14  may be diamond impregnated carbide or similar material used to drill rock, cement, metal or similar materials. Such drill bits are well known in the art. 
         [0024]    The motor  18  and the drill bit  14  may be movably suspended from the rail  16 . The rail  16  may be formed as a tube, rod, box or similar shape and have a length sufficient to enable the drill  15  to be laterally separated from the exterior surface of the manhole (not shown) when the rail  16  is coupled to the base plate  10 . The motor  18  and drill bit  14  may be movably suspended from the rail  16  using a carriage  16 A, for example, a gear box. The carriage  16 A, if a gear box is used therefore, may include an internal gear (not shown) that engages mating teeth (not shown for clarity) on an external surface of the rail  16 . The internal gear (not shown) may be rotated by hand, for example using a crank or knob (not shown), or the internal gear (not shown) may be operated by a gear motor, for example an hydraulic motor, electric motor or a pneumatic motor. The carriage  16 A may provide axial force to the drill  15  so that as the drill bit  14  is rotated by the motor  18 , the drill  15  may be axially advanced so as to drill through the wall of the manhole (not shown in  FIGS. 5 through 8 ). In some embodiments, the carriage  16 A may include a longitudinal position sensor, for example, a linear variable differential transformer (LVDT) in signal communication with a recording device (not shown) such as a small hand held computer. The carriage  16 A may also include, in some embodiments, an axial load sensor such as a strain gauge. The axial load sensor may also be in signal communication with the recording device. The recording device may also generate a control signal to operate a motor as described above which may rotate the internal gear (not shown) in the carriage  16 A. The recording device may be programmed to operate the motor that rotates the internal gear such that longitudinal movement of the carriage  16 A and coincident axial movement of the drill  15  may be controlled automatically. For example, the recording device may be programmed to rotate the internal gear such that a selected axial load is maintained on the drill bit  14 . When the axial position sensor generates a signal indicative of complete penetration of the manhole, the motor  18  may be stopped and the drill  15  may be automatically withdrawn (i.e., moved axially away from the manhole along the rail  16 ). 
         [0025]    In other embodiments, the carriage  16 A may be moved along the rail  16  by different mechanisms. One example may include an internal ball nut in the carriage  16 A. A worm screw (not shown) may be rotatably mounted parallel to the rail  16  such that rotation of the worm screw causes longitudinal movement of the carriage  16 A. In other embodiments, the carriage  16 A may be moved along the rail  16  using an hydraulic cylinder or a pneumatic cylinder. 
         [0026]      FIGS. 6, 7 and 8  show the drill  15  in oblique, end and side views, respectively, wherein a brace  19  and T-bar  20  may be observed. The brace  19  and T bar  20  may be affixed to the mounting plate  10 , e.g., using bolts in selected holes in the perforated edges ( 11  in  FIG. 3 ). The T-bar  20  may extend over the top of the manhole and may transfer part of the axial reactive load from the drill  15  to the manhole. Referring back to  FIG. 5 , the base plate  12  may include holes  12 A at selected positions therein. When the mounting plate  10  is to be positioned on a manhole, the manhole base may be drilled at the position of the holes  12 A in the base plate  12  so that bolts or rods may be inserted therein. Thus, the bottom of the mounting plate  10  may be supported to transfer axial loading of the drill to the manhole (see  FIG. 17 ). 
         [0027]      FIGS. 9 through 12  show top, oblique, end and side views of the drill mounting plate  21  with the rail  16  affixed thereto. Referring in particular to  FIGS. 10 and 11 , the drill mounting plate  21  may include openings in edges thereof as shown so that the drill mounting plate  21  may be affixed to the base plate ( 10  in  FIG. 3 ) at any selected vertical position within the range provided by the perforated edges ( 11 A in  FIG. 2 ). 
         [0028]    In some embodiments, and referring to  FIGS. 13 through 16 , a wheel carriage  22  may be affixed to the mounting plate  10  to enable ease of movement of the base plate to an intended location where the drill is to be used.  FIGS. 13 through 16  show, respectively, a top view, oblique view, end view and side view of the wheel carriage  22 . 
         [0029]    In use, the drilling system described above with reference to  FIGS. 1 through 12  may be transported to a location wherein a manhole is to be drilled. An opening in the ground may be created to provide access to the exterior of the manhole. The mounting plate may be attached to the manhole as explained above, using, for example, rods inserted into holes the manhole base through corresponding holes ( 12 A in  FIG. 5 ) in the base plate. The brace  19  and T-bar  20  (see  FIG. 6 ) may be affixed to the mounting plate  10  to secure the upper end thereof to the manhole. The drill ( 15  in  FIG. 5 ) may be affixed to the mounting plate  10 , wherein the carriage  16 A is disposed proximate a longitudinal end of the rail ( 16  in  FIG. 5 ). The motor  18  may be energized and the carriage  16 A moved as explained above to cause the drill bit  14  to engage the manhole and drill through the wall thereof. When the opening through the wall of the manhole is completed, the opening may be used, for example, to connect a utility conduit thereto. 
         [0030]      FIG. 17  shows an example embodiment of the apparatus as described above mounted to a manhole  30 . The mounting surfaces  11  are shown as substantially conforming to the exterior shape of the manhole  30 . The base  30 A of the manhole  30  is shown supporting the base plate  12 . Rods  12 B may be inserted through the holes ( 12  in  FIG. 5 ) in the base plate  12  to secure the mounting plate  10  to the manhole  30 . The rail  16  is shown affixed to the rail mounting plate  21 , which as shown in the figure may be bolted to the mounting plate  10 . The carriage  16 A is shown suspending the motor  18  from the rail  16  so that the drill ( 15  in  FIG. 5 ) may be moved axially along the rail  16  to drill through the manhole  30 . 
         [0031]    A drill system as described herein may enable rapid, cost efficient creation of additional openings in a manhole that are, when drilled, substantially in condition to accept sealing engagement of a utility pipe or conduit. The drill system when used as described herein may reduce the risk of fracture of a manhole and may substantially reduce the need for surface finishing procedure for the created hole as contrasted with methods known in the art for creating additional openings in a manhole. 
         [0032]    While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the attached claims.