Push reamer

Abstract

In some underground boring applications the exit location of the underground bore may be located such that drill pipe and material pipe sections cannot be conveniently deployed therefrom (e.g., a basement of a building, the inside of another pipe, or a small manhole space). In such applications, push reaming functionality is often the preferred method of reaming because the pipe section can be deployed and installed from a pit where the bore is started during a push reaming operation. The present disclosure provides a new push reaming drill head as well as a new method of push reaming.

What is claimed is: 
     
         1 . A push reaming unit comprising:
 a cutter mounting plate that rotates about an axis of rotation, the cutter mounting plate including a front side having a peripheral portion, the cutter mounting plate at least partially defining at least one through path that extends through the cutter mounting plate from the front side to a rear side;   a plurality of reaming cutters mounted at the peripheral portion of the front side of the cutter mounting plate, the reaming cutters being spaced about the axis of rotation;   a centralizer positioned in front of the cutter mounting plate, the centralizer being co-axially aligned along the axis of the rotation.   
     
     
         2 . The push reaming unit of  claim 1 , wherein the cutter mounting plate and centralizer are arranged and configured such that they can rotate relative to each other. 
     
     
         3 . The push reaming unit of  claim 1 , wherein the centralizer is attached to a centralizer shaft which is supported by a bearing housing that rotates with the cutter mounting plate such that the centralizer shaft can rotate independent of the bearing housing. 
     
     
         4 . The push reaming unit of  claim 1 , wherein the centralizer is generally cylindrical and has a maximum diameter that is smaller than a maximum diameter of the cutter mounting plate. 
     
     
         5 . The push reaming unit of  claim 1 , further comprising a finished bore guide located rearward of the cutter mounting plate, the finished bore guide including a maximum diameter that is larger than a maximum diameter of the centralizer. 
     
     
         6 . The push reaming unit of  claim 1 , further comprising a vacuum intake positioned rearward of the cutter mounting plate and configured to not rotate with the cutter mounting plate. 
     
     
         7 . The push reaming unit of  claim 1 , further comprising a finished bore guide located rearward of the cutter mounting plate, the finished bore guide includes a generally cylindrical rear portion as well as a vacuum intake for receiving cuttings from the bore and directing the cuttings into the drill string. 
     
     
         8 . The push reaming unit of  claim 1 , wherein the through path that extends through the cutter mounting plate from the front side to the rear side is open to a periphery edge of the cutter mounting plate. 
     
     
         9 . The push reaming unit of  claim 1 , further comprising a finished bore guide located rearward of the cutter mounting plate, the finished bore guide being removable from the push reaming unit without first needed to remove the cutter mounting plate or centralizer from the push reaming unit. 
     
     
         10 . A push reaming unit comprising:
 a generally cylindrical main body portion configured to mate with a drill string; the main body including a sleeve fixedly mounted coaxially therein;   a drive stem coaxially arranged within the sleeve;   a bearing housing fixed to the drive stem such that the bearing housing rotates with the drive stem;   a first bearing assembly located within the bearing housing and configured to allow for relative rotation between the drive stem and the sleeve;   a cutter mounting plate connected to the bearing housing such that the cutter mounting plate rotates with the bearing housing and the drive stem;   a centralizer shaft extending forwardly of the cutter mounting plate outwardly from the bearing housing;   a second bearing assembly located within the bearing housing, the second bearing assembling being configured to allow for relative rotation between the bearing housing and the centralizer shaft;   a centralizer mounted to the centralizer shaft forward of the cutter mounting plate, the centralizer being decoupled from rotation of the dive stem; and   a finished bore guide coaxially arranged with the main body portion position rearward of the cutter mounting plate, the finished bore guide including a cross sectional diameter that is larger than the cross sectional diameter or the main body portion and as well as the centralizer;   a cutting vacuum inlet provided on the finished bore guide, the vacuum inlet being at least partially facing the cutter mounting plate.   
     
     
         11 . The push reaming unit of  claim 10 , wherein the cutter mounting plate has a scalloped periphery edge with at least one scallop is located between adjacent cutter mountings on the cutter mounting plate. 
     
     
         12 . The push reaming unit of  claim 10 , wherein the cutter mounting plate is bolted to a radially extending flange of the bearing housing and there the cutter mounting plate is arranged and configured such that it can be removed from the push reaming unit without disassembling the bearing housing. 
     
     
         13 . The push reaming unit of  claim 10 , wherein the centralizer shaft includes step shoulder configuration that secure the centralizer in the radial direction. 
     
     
         14 . The push reaming unit of  claim 10 , wherein the vacuum inlet is located on the bottom portion of the finished bore guide and is configured to funnel cuttings into the cuttings conduit of the main body which is positioned below a sight path. 
     
     
         15 . A method of push reaming comprising:
 selecting a centralizer or a drill head based on the diameter of a pilot bore;   selecting a finished bore guide based on the diameter of the final reamed bore diameter;   connecting the centralizer to a drill head forward of a cutter mounting plate;   connecting the finished bore guide rearward of the cutter mounting plate; and   thrusting the drill head into the pilot bore while rotating the cutter mounting plate.   
     
     
         16 . The method of  claim 15 , wherein the centralizer is not driven to rotate even when the cutter mounting plate is driven to rotate. 
     
     
         17 . The method of  claim 15 , removing cutting from the bore via a vacuum inlet, the vacuum inlet being located rearward of the cutter mounting plate and forward of a rear portion of the finished bore guide. 
     
     
         18 . The method of  claim 15 , connecting the finished bore guide to the drill head without first detaching the centralizer or the cutter mounting plate from the drill head. 
     
     
         19 . The method of  claim 15 , wherein the selection of the finished bore guide is also based in part on the ground condition in which the reaming will be done. 
     
     
         20 . The method of  claim 15 , wherein the cutter mounting plate is bolted to an annular flange of a bearing housing.