U.S. patent application number 10/054759 was filed with the patent office on 2002-08-22 for bit for horizontal boring.
Invention is credited to Caraway, Douglas B..
Application Number | 20020112894 10/054759 |
Document ID | / |
Family ID | 26733461 |
Filed Date | 2002-08-22 |
United States Patent
Application |
20020112894 |
Kind Code |
A1 |
Caraway, Douglas B. |
August 22, 2002 |
Bit for horizontal boring
Abstract
A drill bit for use in horizontal boring includes a bit body
with a central axis of rotation including a forwardmost pilot
section, a reaming section rearwardly of the pilot section
including a forwardly inclined arcuate steering surface and a
plurality of gauge cutting teeth disposed rearwardly of the pilot
section in opposed relationship to the inclined steering section,
the gauge teeth extending farther from the central axis in a radial
direction than the steering section such the arcuate steering
section lies entirely within a circular profile corresponding to
the path of the gauge teeth when the bit is rotated 360.degree. and
a coupling section at a rear end portion of the body configured for
attachments to an adjacent component of the drill sting.
Inventors: |
Caraway, Douglas B.;
(Kingwood, TX) |
Correspondence
Address: |
Philip G. Meyers Intellectual Property Law, P.C.
Suite 302
1009 Long Prairie Road
Flower Mound
TX
75022
US
|
Family ID: |
26733461 |
Appl. No.: |
10/054759 |
Filed: |
January 22, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60263151 |
Jan 22, 2001 |
|
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Current U.S.
Class: |
175/385 ;
175/391; 175/406 |
Current CPC
Class: |
E21B 10/60 20130101;
E21B 10/26 20130101; E21B 7/064 20130101; E21B 10/43 20130101 |
Class at
Publication: |
175/385 ;
175/391; 175/406 |
International
Class: |
E21B 010/26 |
Claims
1. A drill bit for use in horizontal boring comprising: a bit body
with a central axis of rotation including a forwardmost pilot
section, the pilot section configured to form a pilot bore during
drilling operations and stabilize the bit body during rotary
operation; a reaming section rearwardly of the pilot section, the
reaming section including a forwardly inclined arcuate steering
surface and a plurality of gauge cutting teeth disposed rearwardly
of the pilot section in opposed relationship to the inclined
steering section the gauge teeth extending farther from the central
axis in a radial direction than the steering section such the
arcuate steering section lies entirely within a circular profile
corresponding to the path of the gauge teeth when the bit is
rotated 360.degree.; and a coupling section at a rear end portion
of the body configured for attachments to an adjacent component of
the drill sting.
2. The drill bit of claim 1 wherein the steering surface
circumscribes less than 180.degree. of the perimeter of the reaming
section.
3. The drill bit of claim 2 wherein the gauge teeth being
positioned so as to cover a portion of the reaming section
circumscribing less than 180.degree. of the perimeter of the
reaming section.
Description
[0001] This application claims priority of U.S. Provisional Patent
Application Serial No. 60/263,151, filed Jan. 22, 2001.
TECHNICAL FIELD
[0002] The invention relates to a method and apparatus for
directional boring in rocky formations and an improved bit for
drilling therein.
BACKGROUND OF THE INVENTION
[0003] Directional boring apparatus or trench less drills for
making holes through soil are well known. The directional borer
generally includes a series of drill rods joined end to end to form
a drill string. The drill string is pushed or pulled though the
soil by means of a powerful device such as a hydraulic cylinder.
See McDonald et al. U.S. Pat. No. 4,694,913, Malzahn, U.S. Pat.
Nos. 4,945,999 and 5,070,848, and Cherrington, U.S. Pat. No.
4,697,775 (RE 33,793). The drill string may be pushed and rotated
at the same time as described in Dunn, U.S. Pat. No. 4,953,633 and
Deken, et al., U.S. Pat. No. 5,242,026. A spade, bit or head having
one or more angled faces configured for boring is disposed at the
end of the drill string and may include an ejection nozzle for
water or drilling mud to assist in boring.
[0004] In one known directional boring system, the drill bit is
pushed through the soil without rotation in order to steer the tool
by means of the angled face, which is typically a forwardly facing
sloped surface. For rocky conditions, a row of teeth may be added
to the drill bit and the bit operated in the manner described in
Runquist et al. U.S. Pat. No. 5,778,991. Other toothed bits for
directional boring through rock are shown in European Patent
Applications Nos. EP 0 857 852 and EP 0 857 853, Cox U.S. Pat. No.
5,899,283, Skaggs U.S. Pat. No. 5,647,448 and Stephenson U.S. Pat.
No. 5,799,740. Steering systems for use with these devices require
keeping track of the angle of rotation of the sloped face of the
bit and/or the teeth.
[0005] According known systems, a transmitter or sonde mounted in a
tubular housing is mounted behind and adjacent to the bit and sends
a signal that indicates the angle of rotation of the bit. The sonde
is mounted in a predetermined alignment relative to the steering
portion of the bit. The sonde enables steering of the bit during
the horizontal drilling operation. See generally Mercer U.S. Pat.
Nos. 5,155,442, 5,337,002, 5,444,382 and 5,633,589, Hesse et al.
U.S. Pat. No. 5,795,991, and Stangl et al. U.S. Pat. No.
4,907,658.
[0006] According to one known directional boring system, the drill
bit is pushed through the soil without rotation to steer the tool
by means of an angled face which is typically a forwardly sloping
face. For rocky conditions, a row of teeth may be added to the
drill bit and the bit operated in the manner described in Runquist
et al., U.S. Pat. No. 5,778,991. Other toothed bits for directional
drilling through rock are shown in Cox U.S. Pat. No. 5, 899,283,
Skaggs U.S. Pat. No. 5,647,488 and Stephenson U.S. Pat. No. 5,799,
740.
[0007] The "duckbill" style of bit, conventionally mounted directly
on a forwardly sloped face of a sonde housing, is inexpensive,
generally easy to replace, and has the advantage of simplicity. Six
bolts, which may be countersunk, hold the duckbill in place. The
bit itself is little more than a flat steel plate that protrudes
beyond the front end of the sonde housing. The bit may have teeth
to aid in directional drilling through rocky conditions. The bolts
that hold the bit on, however, tend to loosen or fail under the
large shear forces to which the bit is subjected, and once the bit
breaks off, the bore must be discontinued and the drill head
withdrawn.
[0008] A dual-purpose bit designed for directional boring through
soil and horizontal drilling in rock, known as the Trihawk.TM. is
described in PCT publication No. 00/11303, published Mar. 2, 2000.
The Trihawk bit has three replaceable canted teeth set to cut a
series of annular grooves which form the outer part the borehole
when drilling in rock. A mound or cone forms at the center of the
borehole that is progressively broken down against the steering
face as the bit advances. This bit is effective for drilling in
dirt, soft rock and medium rock. The present invention provides a
bit with similar capabilities without canted teeth.
DESCRIPTION OF THE DRAWINGS
[0009] In the accompanying drawings, wherein like numerals denote
like elements:
[0010] FIG. 1 is perspective view of the bit of the invention;
[0011] FIG. 2 is a side view of the bit of the invention;
[0012] FIG. 3 is a front view of the bit of the invention;
[0013] FIG. 4 is a rear view of the bit of the invention;
[0014] FIG. 5 is a top view of the bit of the invention positioned
in an outline of a bore profile;
[0015] FIG. 6 is a side view of the bit of the invention positioned
in an outline of a bore profile;
[0016] FIG. 7 is a front view of the bit of the invention
positioned in an outline of a bore profile;
[0017] FIGS. 8-10 are side, top and side views of the bit of the
invention;
[0018] FIG. 11 is a partial cross sectional view of the bit of the
invention taken along line C-C of FIG. 7; and
[0019] FIG. 12 is a partial cross sectional view of the bit of the
invention taken along line B-B of FIG. 7.
[0020] While the making and using of various embodiments of the
present invention are discussed in detail below, it should be
appreciated that the present invention provides many applicable
inventive concepts which can be embodied in a wide variety of
contexts. The embodiments discussed herein are merely illustrative
of specific ways to make and use the invention and do not limit the
scope of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0021] Referring now to FIGS. 1-12 a bit 10 in accordance with the
invention comprises a bit body 12 including a pilot section 14 and
reaming section 16, the reaming section having a larger diameter
than pilot section 14. Pilot section 14 includes a nose section 18,
a slightly concave face 28 with a plurality of forwardly projecting
nose inserts (carbide studs) 20 disposed in holes 34, a shoulder
section 22 including a plurality of spaced apart shoulder inserts
24 located in holes 36, and a cylindrical pilot body 26. A
plurality of cut outs 30 are formed in shoulder section 22 and
circumferentially located around the perimeter of shoulder section
22. As shown, shoulder section 22 forms a curved transition from
nose section 18 to body section 22.
[0022] A plurality of outlets 32 located in nose section 18 provide
for the flow of a pressurized fluid to the pilot section 14 to
lubricate the bit during drilling operations and to sweep away
material such as dirt, rock and debris from the pilot section 14.
Cut outs 30 facilitate the sweeping action of the pressurized
fluid, providing a passageway through with the mixture of drilling
fluid and debris may pass during the drilling operation. Nose
inserts 20 and shoulder inserts 24 are preferably carbide studs and
are secured with an interference fit or may be brazed in place.
Nose inserts 20 serve to cut into and grind away the face of the
borehole as it is being drilled, especially rock formations.
Shoulder inserts 24 are strategically placed so as to protect the
base metal of pilot section 14 from abrasion while simultaneously
cutting and widening the pilot bore created by the nose section 18
as well as grinding up material and debris dislodged in the
drilling operation.
[0023] Reaming section 16 of bit body 12 includes a pair of
substantially flat, parallel opposed sides 40 and an acuate,
forwardly inclined steering section 42 extending between sides 40
on a first side of the bit. The steering section 42 is semi frustro
conical in shape, being inclined, arcuate and circumscribing less
than 180.degree. of the perimeter or circumference of reaming
section 16 of bit body 12. As best shown in FIG. 10, steering
section 42 is forwardly inclined at an angle .alpha. of
approximately 20.degree., although a greater or lesser angle may be
used.
[0024] A plurality of reaming ribs 44, including a central rib 44',
also extend between sides 40 in opposed relationship to steering
section 42 on a second side of the bit and are forwardly inclined
toward pilot section 14. Each rib 44 includes a row of cutting or
gauge teeth 46 disposed in spaced apart relationship along the
length of the rib. As illustrated, a plurality of intermediate
inserts, (two shown) between the gauge teeth 46 of central rib 44'
and shoulder section 22 of pilot section 14. As best shown in FIG.
6, intermediate teeth 47 are positioned inside the pilot bore
profile 49 and engage the bore only when the bit is operated in the
push-to-steer or push and partial rotate to steer modes as
described below. Intermediate teeth 47 also serve to protect the
base metal of the corresponding portion of cylindrical pilot body
26. Preferably, gauge teeth 46 and intermediate teeth 47 comprise
carbide studs and are positioned so as to protect the base metal of
the bit while simultaneously cutting and widening the bore formed
by pilot section 14. Gauge teeth 46 and intermediate teeth 47 may
be interference fit or brazed into apertures 48.
[0025] As best shown in FIG. 7, forwardly inclined steering surface
42 circumscribes less than 180.degree. of the perimeter or
circumference of the bit body 12. Likewise reaming ribs 44 also
circumscribe less than 180.degree. of the perimeter or
circumference of bit body 12. Ribs 44 are also positioned opposite
inclined steering surface 42. It will also be appreciated that
gauge teeth 46 project farther out form the central axis 60 of the
bit than does inclined steering surface 42. Thus, when the bit is
operated in the rotary mode, normally inclined steering surface 42
will have no contact, or minimal contact with the outside perimeter
or profile 53 of the bore. In other words, inclined steering
section 42 circumscribes less than 180.degree. of the perimeter of
the reaming section. Similarly, the gauge teeth being positioned so
as to cover a portion of the reaming section circumscribing less
than 180.degree. of the perimeter of the reaming section opposite
the steering section 42. Since the gauge teeth 46 extend farther
from the central axis in a radial direction than the steering
section 42, the steering section will lie entirely within a
circular profile 53 corresponding to the path of the gauge teeth
when the bit is rotated 360.degree. irrespective of the rotary
position of the bit 10.
[0026] A fluid outlet 57 (one shown) is located on each of
longitudinally inclined ribs 44 for the passage of drilling fluid
to lubricate the reamer section and to sweep cutting away during
drilling operations. Each fluid outlet 32, 57 communicates with an
interior passage 62 (FIG. 11) in bit body 12 to supply the reaming
section 16 of bit 10 with drilling fluid. Extending longitudinally
between ribs 44 are cut outs 50 that facilitate the flow of
drilling fluid and debris around and past the bit 10 during
drilling operations.
[0027] Bit 10 also includes a coupling section 52. Coupling section
52 includes a grooved socket 54 designed to receive a splined
projection at the front of an adjoining sonde housing component as
described in U.S. Pat. No. 6,148,935 to Wentworth et al and
assigned to Earth Tool Company L.L.C., of Oconomowoc Wis., the
entire contents of which are incorporated herein for all purposes.
A pair of transverse holes 56, 58 on either side of central
longitudinal axis 60 of bit body 12 are provided for insertion of
roll pins or other retainers that hold bit 10 on the front end of a
sonde housing or other adjacent drill string component or tool.
Alternatively, coupling section 52 may comprise a splined
projection rather than a socket or any other connection suitable
for mounting a bit on a drill string as known in the art such as by
a threaded connection or an end portion profiled to fit against a
surface of a sonde housing or similar tool with holes there through
for bolts. Bit 10 also includes one or more fluid passages 62,
(FIGS. 11 and 12) extending through bit body 12 to carry
pressurized drilling fluid from socket 54 to outlets 32 in nose 18
to lubricate bit 10 and sweep away debris generated in the drilling
operation.
[0028] In normal rotary operation, bit 10 will drill a straight
bore with pilot section 14 stabilizing the bit. In this mode,
steering section 42 will have minimal or no contact with the bore
as illustrated by FIG. 7 wherein the steering section lies entirely
within circular bore profile 53. In a push-to-steer mode of
operation, inclined steering section 42 may be used to steer bit
through dirt by forward thrust without rotation. In particular, in
dirt and/or soft formations, longitudinally inclined ribs 44 will,
as best shown in FIG. 3, present a smaller transverse cross
sectional area than the inclined steering section 42, positioned on
the opposite side of the bit. Thus, the side or portion of reaming
section 16 where ribs 44 are positioned will present less
resistance to forward movement through soft strata. Since the side
of the bit 10 where ribs 44 are positioned will penetrate soft
strata with less resistance than steering section 42, with its
larger transverse cross section, the operator may steer bit 10 by
orienting the bit with steering surface 42 positioned on the side
of the bore opposite the direction in which is desired to steer the
bit. Additionally, ribs 44 and gauge teeth 46 will selectively
loosen the formation in the desired direction of travel, allowing
pressurized drilling material to sweep the loosened material away,
thereby aiding the steering function.
[0029] In order to steer the bit 10 through a hard formation in the
desired direction, such as up or down, bit 10 may be utilized in a
push-and-partial-rotate mode. In this mode, bit 10 is rotated
through an arc less than 360.degree. causing the gauge teeth to cut
a semicircular profile in the desired direction of travel. Steering
section 42 of reamer section 16 provides an angled surface to push
the bit 10 in the desired direction as the bit is rotated though
the arc. After the arc is cut, bit 10 is retracted and rotated back
a like distance, or the rotation is completed with the bit is
withdrawn so that no cutting occurs. Bit 10 is then returned to
engagement at the same location and the steps are repeated. This
process gradually results in a change in boring direction, after
which the mode of operation is returned to normal to form a
circular borehole.
[0030] Used in the above-described modes, the bit of the invention
can drill a borehole through a soft or hard substrate, the bore
being curved or having several angled segments representing, for
example, initial entry into the ground, horizontal boring under an
obstacle such as a roadway, and upward travel towards the surface
at the end of the borehole.
[0031] While certain embodiments of the invention have been
illustrated for the purposes of this disclosure, numerous changes
in the invention presented herein may be made by those skilled in
the art, such changes being embodied within the scope and spirit of
the present invention as defined in the appended claims.
* * * * *