U.S. patent application number 14/442784 was filed with the patent office on 2015-11-19 for push reamer.
The applicant listed for this patent is Edwin G. SPOELSTRA, VERMEER MANUFACTURING COMPANY. Invention is credited to Edwin G. SPOELSTRA, Jeffrey James UTTER.
Application Number | 20150330148 14/442784 |
Document ID | / |
Family ID | 50731718 |
Filed Date | 2015-11-19 |
United States Patent
Application |
20150330148 |
Kind Code |
A1 |
UTTER; Jeffrey James ; et
al. |
November 19, 2015 |
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.
Inventors: |
UTTER; Jeffrey James;
(Prairie City, IA) ; SPOELSTRA; Edwin G.;
(Leighton, IA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SPOELSTRA; Edwin G.
VERMEER MANUFACTURING COMPANY |
Leighton
Pella |
IA
IA |
US
US |
|
|
Family ID: |
50731718 |
Appl. No.: |
14/442784 |
Filed: |
November 15, 2013 |
PCT Filed: |
November 15, 2013 |
PCT NO: |
PCT/US2013/070314 |
371 Date: |
May 14, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61726999 |
Nov 15, 2012 |
|
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|
Current U.S.
Class: |
175/62 ;
175/325.1 |
Current CPC
Class: |
E21B 7/046 20130101;
E21B 7/28 20130101; E21D 9/004 20130101; E21B 3/00 20130101; E21B
10/28 20130101; E21B 17/1078 20130101; E21B 10/08 20130101 |
International
Class: |
E21B 7/04 20060101
E21B007/04; E21B 10/28 20060101 E21B010/28; E21B 17/10 20060101
E21B017/10; E21B 3/00 20060101 E21B003/00 |
Claims
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.
Description
[0001] This application is being filed on 15 Nov. 2013, as a PCT
International patent application, and claims priority to U.S.
Provisional Patent Application No. 61/726,999, filed Nov. 15, 2012,
the disclosure of which is hereby incorporated by reference herein
in its entirety.
TECHNICAL FIELD
[0002] The present disclosure relates generally to trenchless
drilling equipment. More particularly, the present disclosure
relates to tunneling equipment capable of reaming a pre-bored hole
to enlarge the diameter of the hole.
BACKGROUND
[0003] Modern installation techniques provide for the underground
installation of services required for community infrastructure.
Sewage, water, electricity, gas and telecommunication services are
increasingly being placed underground.
[0004] One method for installing underground services involves
excavating an open trench. However, this process is time consuming
and is not practical in areas supporting existing construction.
[0005] Other methods for installing underground services involve
boring an underground hole. In some underground applications an
underground hole is bored from above the ground surface and back up
through the ground surface (e.g., horizontal drilling machines). In
other applications the underground hole is bored from a first pit
to an exit location, which may be a second pit (e.g., on grade
drilling machines). Vermeer Manufacturing's PCT International
Publication No. 2012/040190 (WO 2012/166905) and U.S. Pat. No.
7,942,217, U.S. Pat. No. 8,151,906 discloses a micro-tunneling
system and apparatus capable of boring and back-reaming an
underground micro-tunnel at precise grade and line, these
publications are all hereby incorporated by reference in their
entirety.
SUMMARY
[0006] In on grade application (drilling straight bores), a first
pit is typically formed sufficiently large to allow for the set up
drill apparatus which receives and deploys drill casings during
boring, and the second pit is formed generally sufficiently large
to deploy the pipe sections that are installed during a pullback
reaming operation. However, in some circumstances the exit location
of the underground bore may be located such that the pipe sections
cannot be deployed therefrom (e.g., a basement of a building, the
inside of another pipe, or a small manhole space under a busy
roadway). In such applications, push reaming functionality is often
the preferred method of reaming because the pipe section can be
deployed and installed from the first pit during a push reaming
operation.
[0007] One aspect of the present disclosure relates to a
thrust/push reaming system for enlarging the diameter of a
pre-bored hole. In one example, the reaming system includes a
cutter mounting plate that is rotated by a rotational driver of the
system about a central axis of rotation. The cutter mounting plate
includes a front face having a peripheral portion that surrounds
the axis of rotation. A plurality of reaming cutters is mounted to
the peripheral portion of the front face. In one example, the
reaming cutters can include bits (e.g., tri-cone bits) that are
rotatable relative to the cutter mounting plate. In one example,
the bits can each include a main body rotatably mounted on a
shaft/pin secured to the cutter mounting plate, and a plurality of
cutting elements (e.g., carbide buttons) embedded in or otherwise
anchored to the main body. The system can also include a guide or
centralizer that advances in front of the cutter mounting plate
within the pre-bored hole during reaming. The guide is configured
to fit within the pre-bored hole in advance of the cutter mounting
plate so as to center the cutter mounting plate relative to the
pre-bored hole. In one example, the centralizer can be a
cylindrical sleeve having a hollow interior. An attachment
structure (e.g., a plurality of robust bars, rods, plates, etc.)
extends forwardly from the cutter mounting plate and connects the
centralizer to the cutter mounting plate. In one example, the
cutter mounting plate, the attachment structure and the centralizer
can all rotate together as a unit about the central axis of
rotation during reaming operations. In other examples, relative
rotation can be provided between the centralizer and the cutter
mounting plate such that during reaming the cutter mounting plate
rotates to enlarge the hole while the centralizer does not rotate
within the pre-bored hole. To allow for relative rotation, bearings
can be provided between the centralizer and the attachment
structure, between the attachment structure and the cutter mounting
plate, or elsewhere. In one example, the centralizer is hollow to
allow any cuttings or other material present in the pre-bored hole
to pass through the centralizer to the cutter mounting plate. The
cutter mounting plate can define one or more through-holes for
allowing cuttings generated during reaming and/or material that
passes through the centralizer to pass through the cutter mounting
plate from the front side to a back side of the cutter mounting
plate. A vacuum intake of a cuttings removal system can be provided
near the back side of the cutter mounting plate for drawing-in
material that passes through the through-holes and evacuates the
material from the reamed hole. Gasketing can be provided between
the vacuum intake and the back side of the cutter mounting plate to
enhance suction. Fins or other structures can be provided on a
front side of the cutter mounting plate for directing/lifting
cuttings from the bottom of the reamed hole toward the
through-holes. In one example, the reaming cutters define a cutting
diameter that is at least 5, 10, or 20 percent larger than a
cross-dimension (e.g., outer diameter) of the centralizer.
[0008] A variety of additional aspects will be set forth in the
description that follows. The aspects can relate to individual
features and to combinations of features. It is to be understood
that both the foregoing general description and the following
detailed description are exemplary and explanatory only and are not
restrictive of the broad inventive concepts upon which the
embodiments disclosed herein are based.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a schematic depiction of a push reaming apparatus
having features in accordance with the principles of the present
disclosure;
[0010] FIG. 2 is an enlarged view of a portion of FIG. 1;
[0011] FIG. 3 is a top elevation view of an alternative embodiment
of a push reaming apparatus in accordance with the principles of
the present disclosure;
[0012] FIG. 4 is a cross-sectional view along line 4-4 of FIG.
3;
[0013] FIG. 5 is a first end view of the push reaming apparatus of
FIG. 3; and
[0014] FIG. 6 is a second end view of the push reaming apparatus of
FIG. 3.
DETAILED DESCRIPTION
[0015] FIG. 1 shows a push reaming apparatus 20 having features in
accordance with the principles of the present disclosure. The push
reaming apparatus is configured to enlarge a pre-bored hole 200
using a push reaming process. During the push reaming process, the
push reaming apparatus 20 reams the pre-bored bole 200 to create a
reamed hole 202 having a larger diameter than the pre-bored bole
200.
[0016] Generally, the apparatus 20 includes a plurality of pipe
sections 22 that are coupled together in an end-to-end relationship
to form a drill string 24. Each of the pipe sections 22 includes a
drive shaft 26 rotatably mounted in an outer casing assembly 28. A
drill head 30 is mounted at a distal end of the drill string 24,
while a drive unit 32 is located at a proximal end of the drill
string 24. The drive unit 32 includes a torque driver adapted to
apply torque to the drill string 24 and an axial driver for
applying thrust or pull-back force to the drill string 24. Thrust
or pull-back force from the drive unit 32 is transferred between
the proximal end to the distal end of the drill string 24 by the
outer casing assemblies 28 of the pipe sections 22. Torque is
transferred from the proximal end of the drill string 24 to the
distal end of the drill string 24 by the drive shafts 26 of the
pipe sections 22 which rotate relative to the casing assemblies 28.
The torque from the drive unit 32 is transferred through the
apparatus 20 by the drive shafts 26 and ultimately is used to
rotate a cutter mounting plate 33 of a push reaming unit 34 of the
drill head 30. Optional skids 204 can be provided at bottom sides
of the outer casing assemblies for assisting in centering the drill
string within the reamed hole 202. Other types of centralizers
could also be used.
[0017] The pipe sections 22 can also be referred to as drill rods,
drill stems or drill members. The pipe sections are typically used
to form an underground bore, and then are removed from the
underground bore when product (e.g., piping) is installed in the
bore.
[0018] The drill head 30 of the drilling apparatus 20 can include a
drive stem 46 rotatably mounted within a main body 38 of the drill
head 30. A distal end of the drive stem 46 is configured to
transfer torque to the cutter mounting plate 33. A proximal end of
the drive stem 46 couples to the drive shaft 26 of the distal-most
pipe section 22 such that torque is transferred from the drive
shafts 26 to the drive stem 46. In this way, the drive stem 46
functions as the last leg for transferring torque from the drive
unit 32 to the push reaming unit 34. The outer casing assemblies 28
transfer thrust and/or pull back force to the main body 38 of the
drill head. The drill head 30 preferably includes bearings (e.g.,
axial/thrust bearings and radial bearings) that allow the drive
stem 46 to rotate relative to the main body 38 and also allow
thrust or pull-back force to be transferred from the main body 38
through the drive stem 46 to the push reaming unit 34.
[0019] To assist in drilling, the tunneling apparatus 20 can also
include a fluid pump 63 for forcing drilling fluid from the
proximal end to the distal end of the drill string 24. In certain
embodiments, the drilling fluid can be pumped through a central
passage 45 defined through the drive shafts 26. The central passage
45 defined through the drive shafts 26 can be in fluid
communication with at least one fluid delivery port provided at a
front face of the cutter mounting plate 33 such that the drilling
fluid is readily provided at a reaming interface of the push
reaming unit 34.
[0020] During reaming, the cutter mounting plate 33 is rotated by
the rotational driver of the drive unit 32 about a central axis of
rotation 206. The cutter mounting plate 33 includes a front face
208 having a peripheral portion 210 that surrounds the axis of
rotation 206. A plurality of reaming cutters 211 are mounted to the
peripheral portion 210 of the front face 208. In one example, the
reaming cutters 211 can include bits (e.g., tri-cone bits) that are
rotatable relative to the cutter mounting plate 33. In one example,
the bits can each include a main body rotatably mounted on a
shaft/pin secured to the cutter mounting plate 33, and a plurality
of hardened elements (e.g., carbide buttons) embedded in or
otherwise anchored to the main body.
[0021] The system can also include a guide or centralizer 212 that
advances in front of the cutter mounting plate 33 within the
pre-bored hole 200 during reaming. The centralizer 212 is
configured to fit within the pre-bored hole 200 in advance of the
cutter mounting plate 33 so as to center the cutter mounting plate
33 relative to the pre-bored hole 200. In one example, the
centralizer 212 has an outer diameter that is only slightly smaller
than the diameter of the pre-bored bole 200. In one example, the
centralizer 212 can be a cylindrical sleeve having a hollow
interior 214.
[0022] An attachment structure 216 (e.g., a plurality of robust
bars, rods, plates, etc.) extends forwardly from the cutter
mounting plate 33 and connects the centralizer 212 to the cutter
mounting plate 33. In one example, the cutter mounting plate 33,
the attachment structure 216 and the centralizer 212 can all rotate
together as a unit about the central axis of rotation 206 during
reaming operations. In other examples, relative rotation can be
provided between the centralizer 212 and the cutter mounting plate
33 such that during reaming the cutter mounting plate 33 rotates to
enlarge the pre-bored hole while the centralizer 212 does not
rotate within the pre-bored hole. To allow for relative rotation,
bearings can be provided between the centralizer 212 and the
attachment structure 216, between the attachment structure 216 and
the cutter mounting plate 33, or elsewhere.
[0023] In one example, the centralizer 212 is hollow to allow
cuttings or other material present in the pre-bored hole 200 to
pass through the centralizer 212 to the cutter mounting plate 33 as
the drill string is forwardly advanced (e.g., thrusted forwardly
via thrust provided by the drive unit 32) during reaming. The
cutter mounting plate 33 can define one or more through-holes 218
for allowing cuttings generated during reaming and/or material that
passes through the centralizer 212 to pass through the cutter
mounting plate 33 from the front side 208 to a back side 220 of the
cutter mounting plate 33. A vacuum intake 222 of a cuttings removal
system can be provided near the back side 220 of the cutter
mounting plate 33 for drawing-in material that passes through the
through-holes 218. The cuttings removal system can include a vacuum
source 65 (e.g., a vacuum source above ground or at the distal end
of the hole) that applies vacuum to a vacuum passage that extends
from the vacuum source, through the drill string, to the vacuum
intake 222. In this way, the cuttings removal system can draw
cuttings and drilling fluid out of the reamed hole and can convey
the cuttings and drilling fluid to a storage receptacle outside the
reamed hole.
[0024] Gasketing can be provided between the vacuum intake and the
back side of the cutter mounting plate to enhance suction. Fins or
other structures can be provided on a front side of the cutter
mounting plate for directing/lifting cuttings from the bottom of
the reamed hole toward the through-holes. In one example, the
reaming cutters define a cutting diameter that is at least 5, 10,
or 20 percent larger than a cross-dimension (e.g., outer diameter)
of the centralizer.
[0025] Referring to FIGS. 3-6, an alternative embodiment of a push
reaming apparatus is described in further detail. In the depicted
embodiment the drill head 100 is configured to connect to a distal
end of the drill string 24 via a connection interface 102 on a
second end portion 104 of the drill head 100. The drill head
includes a main body 106 that supports a rotatable drive stem 108
that extends coaxially therethrough. The drive stem 108 is
configured to rotate the cutter mounting plate 110. The cutter
mounting plate 110 includes a front face 112 that includes a
plurality of reaming cutters 114 mounted to peripheral portion 116
of the cutter mounting plate 110. The cutter mounting plate 110
includes a plurality of spaced apart through-holes 118 located
around the periphery portion 116 of the cutter mounting plate 110.
In the depicted embodiment the through-holes 118 are open to and
coincident with the periphery edge 120 of the cutter mounting plate
110.
[0026] In the depicted embodiment the drill head 100 includes an
attachment structure 122 that extends forwardly from the cutter
mounting plate 110. The attachment structure 122 connects a
centralizer 124 to the drill head 100. In the depicted embodiment
centralizer 124 can idle (not rotate) while the cutter mounting
plate 110 rotates.
[0027] In the depicted embodiment the drill head 100 includes a
finished bore guide 126. The finished bore guide 126 provides
additional stabilization to the drill head and also collects the
cutting from the bore via vacuum intake 128 that faces and is
rearward of the back side 130 of the cutter mounting plate 110. As
the drill head 100 advances, cuttings are driven into the vacuum
intake 128 and vacuumed through the central passage 130 of the
drill head 100. In the depicted embodiment the finished bore guide
126 is generally cylindrical in shape with an outer diameter that
is slightly smaller than the diameter of the reamed bore diameter.
In the depicted embodiment the finished bore guide includes
straight sidewalls 170 (i.e., the finished bore guide is in the
shape of a constant diameter cylinder) and includes small tapers
172, 174 at both the leading edge and the trailing edge. It should
be appreciated that in alternative embodiments the finished bore
guide could include a tapered side wall, for example, wherein the
diameter of the finished bore guide increases from the distal end
to the proximal end. In the depicted embodiment the finished bore
guide 126 includes a two-piece construction including a first
section 176 and a second section 178 such that the finished bore
guide 126 can be attached and detached from the drill head 100.
[0028] Referring to FIG. 4 the assembly of the drill head 100 is
described in further detail. In the depicted embodiment the drive
stem 108 is coaxially positioned within sleeve 132. The sleeve 132
is fixed to the main body 106, which is generally cylindrical. The
drive stem 108 is hex fit into an end plate 134. The end plate 134
is bolted to an inner bearing housing 136. The bearing housing 136
is bolted to the cutter mounting plate 110 and rotates with the
cutter mounting plate 110.
[0029] In the depicted embodiment, a first bearing assembly 138 is
arranged within the bearing housing 136 to allow the bearing
housing 136 to rotate relative to the sleeve 132, which is fixed to
the main body 106. The first bearing assembly 138 includes a pair
of thrust bearings 150, 152 positioned between a pair of radial
bearings 154, 156. A second bearing assembly 140 is arranged within
the bearing housing 136 and allows a centralizer shaft 142 to
remain stationary or idle relative to the drive stem 108 and the
cutter mounting plate 110. The second bearing assembly 140 includes
a pair of thrust bearings 158, 160 that are located on the
centralizer shaft 142 between a shoulder 162 and a collar 164.
[0030] In the depicted embodiment the bearing housing 136 includes
a first portion that encloses the first bearing assembly 138. The
first portion includes a rear portion 143 and a front portion 146.
The front portion 146 includes telescoping construction with a
shoulder for seating the cutter mounting plate 110. The bearing
housing 136 includes a second portion 148 that encloses the second
bearing assembly 140. The second portion 148 has an outer diameter
that is less than a central aperture in the mounting plate 110.
This configuration allows the mounting plate 110 to be connected
and disconnected from the drill head 100 without disassembling the
bearing housing 136.
[0031] In the depicted embodiment the centralizer 124 is bolted to
a distal end 180 of the centralizer shaft 142. The centralizer
shaft includes a stepped first shoulder 166 and second shoulder 168
that cooperatively seat and provides stability to the centralizer
124. The configuration enables the centralizer 124 to be connected
and disconnected to the drill head without disassembling the
bearing housing 136 and without removing the cutter mounting plate
110. In the depicted embodiment the distal end 180 of the
centralizer shaft 142 is threaded to receive a nut 144 that secures
the centralizer 124 to the centralizer shaft 142.
[0032] The drill head 100 is configured such that it can be used to
enlarge a bore by thrusting/pushing it through a pilot bore.
Product material such as sections of sewer pipe, water lines,
conduit, etc. can be attached rearward of the finished bore guide
126 and be pulled into the bore simultaneous with the reaming
process. In one embodiment the product material would be attached
to the drill head 100 at a first pit and dragged by the drill head
100 to an end location. The end location could be a second pit,
another pipe, a crawl space, the basement of a building, etc. This
method of installing product material deployed from the first pit
wherein the boring machine is especially useful wherein the far end
of the bore (the exit of the bore) is not conducive to the
deployment of product material. For example, when the far end of
the bore is in the basement of a building, it can be difficult to
get product material into the basement so that it can be pulled
back through the bore during a back reaming operation. In such an
application, push reaming provides significant advantages.
[0033] In the depicted embodiment the drill head 100 is constructed
such that the centralizer 124, the cutter mounting plate 110, and
the finished bore guide 126 are all interchangeable. In the
depicted embodiment the centralizer 124, the cutter mounting plate
110, and the finished bore guide 126 can all be replaced without
opening up the bearing housing 136. As discussed above, the
centralizer 124 can be removed by removing a single nut 144. Once
removed, the cutter mounting plate 110 can be removed by unbolting
it from the bearing housing flange 182. The finished bore guide 126
can be removed by unbolting the first section 176 and a second
section 178. The finished bore guide can be removed and replaced
independently. In other words, it can be removed and replaced
without first removing the centralizer 124 or the cutter mounting
plate 110. This modular configuration provides advantages as the
selection of components can be optimized based on ground
conditions. For example, when drilling through softer materials,
the outer size of the centralizer 124 may be very close to the
diameter of the pilot hole, and the other size of the bore guide
may be very close to the diameter of the bore that is reamed by the
cutters on the cutter mounting plate 110. In ground conditions that
are more stable or harder, it may be desirable to allow for more
clearance between the pilot bore and the centralizer by using a
smaller centralizer and more clearance between the reamed bore and
the finished bore guide.
[0034] In the embodiment depicted above, the push reaming unit
comprises the following features: 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 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; an
attachment structure that connects the centralizer to the cutter
mounting plate; and a finished bore guide located rearward of the
cutter mounting plate, the finished bore guide being removable
without first removing the cutter mounting plate or centralizer. In
the depicted embodiment the centralizer is attached to a
centralizer shaft which is supported by a housing that rotates with
the cutter mounting plate such that the shaft can rotate
independent of the housing. The centralizer is cylindrical and has
a maximum diameter that is smaller than a maximum diameter of the
cutter mounting plate and the finished bore guide includes a
maximum diameter that is larger than a maximum diameter of the
centralizer. The unit also includes a finished bore guide located
rearward of the cutter mounting plate, the finished bore guide
includes a vacuum intake to receiving cuttings from the bore and
directing the cuttings into the drill string. In the depicted
embodiment the through path that extends through the cutter
mounting plate from the front side to a rear side is open to a
periphery edge of the cutter mounting plate. It should be
appreciated that many alternative configurations are also
possible.
[0035] In one embodiment a push reaming unit according to the
present disclosure includes: 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
supported 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; a centralizer shaft extending forwardly of the
cutter mounting plate from the bearing housing; a second bearing
assembly located within the bearing housing and configured to allow
for relative rotation between the bearing housing and the
centralizer shaft; a centralizer supported on the centralizer shaft
forward of the cutter mounting plate; and a finished bore guide
coaxially arranged with the main body positioned rearward of the
cutter mounting plate, the finished bore guide including a cutting
vacuum inlet. In the embodiment depicted in FIGS. 3-5 the cutter
mounting plate has a scalloped periphery edge with the scallops
located between adjacent cutter mountings. The cutter mounting
plate is shown bolted to a radially extending flange of the bearing
housing. The centralizer shaft includes a step shoulder
configuration that secures the centralizer in the radial direction.
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 position below a sight path that
extends through the main body of the drill head. It should be
appreciated that many alternative configurations are also possible
which may include more or fewer features as well as different
features. For example, it should be appreciated that fluid such as
water can be delivered to the bore via hoses to aid in flushing of
the cutting out of the bore.
[0036] The present disclosure provides a method of push reaming
that in one embodiment includes the following steps: 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 and also in part on the ground condition in
which the reaming will be done; connecting the centralizer to a
drill head forward of a cutter mounting plate; connecting the
finished bore guide rearward of the cutter mounting plate;
thrusting the drill head into the pilot bore while rotating the
cutter mounting plate; and removing cuttings from the bore via a
vacuum inlet located rearward of the cutter mounting plate and
forward of a rear portion of the finished bore guide. In the
embodiment disclosed in FIGS. 3-5, the centralizer is not driven to
rotate even when the cutter mounting plate rotates. As discussed
above the finished bore guide in the embodiment depicted in FIGS.
3-5 can be detached from the drill head without detaching the
centralizer or the cutter mounting plate from the drill head. As
discussed above, the cutter mounting plate in the embodiment
depicted in FIGS. 3-5 is bolted to an annular flange of a bearing
housing. It should be appreciated that alternative embodiments may
include fewer steps, different steps, and/or a different
combination of steps
[0037] Various modifications and alterations of this disclosure
will become apparent to those skilled in the art without departing
from the scope and spirit of this disclosure, and it should be
understood that the scope of this disclosure is not to be unduly
limited to the illustrative examples set forth herein.
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