U.S. patent application number 12/693992 was filed with the patent office on 2010-08-05 for track and sprocket drive for drilling.
This patent application is currently assigned to TARGET DRILLING, INC.. Invention is credited to Ryan A. Barnett, Wesley C. Riddle.
Application Number | 20100193247 12/693992 |
Document ID | / |
Family ID | 42396773 |
Filed Date | 2010-08-05 |
United States Patent
Application |
20100193247 |
Kind Code |
A1 |
Riddle; Wesley C. ; et
al. |
August 5, 2010 |
Track and Sprocket Drive for Drilling
Abstract
A drilling rig includes a mast base and a mast having a
structural frame extending from the mast base. The structural frame
includes a first track extending along the length of the structural
frame and a second track extending along the length of the
structural frame spaced from and parallel to the first track. The
drilling rig also includes a top drive carriage assembly having at
least one sprocket arrangement operatively engaged with one of the
first track and the second track. The first track and the second
track each include a plurality of bushings equally spaced apart and
attached to spaced apart track plates. The at least one sprocket
arrangement has a plurality of teeth configured to operatively
engage the plurality of bushings such that the top drive carriage
assembly moves along the length of the structural frame of the
mast.
Inventors: |
Riddle; Wesley C.;
(Fairmont, WV) ; Barnett; Ryan A.; (Fairmont,
WV) |
Correspondence
Address: |
THE WEBB LAW FIRM, P.C.
700 KOPPERS BUILDING, 436 SEVENTH AVENUE
PITTSBURGH
PA
15219
US
|
Assignee: |
TARGET DRILLING, INC.
Jefferson Hills
PA
|
Family ID: |
42396773 |
Appl. No.: |
12/693992 |
Filed: |
January 26, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61148582 |
Jan 30, 2009 |
|
|
|
Current U.S.
Class: |
175/57 ;
175/170 |
Current CPC
Class: |
E21B 19/083
20130101 |
Class at
Publication: |
175/57 ;
175/170 |
International
Class: |
E21B 3/00 20060101
E21B003/00 |
Claims
1. A drilling rig comprising: a mast base; a mast comprising a
structural frame extending from the mast base, the structural frame
including a first track extending along the length of the
structural frame and a second track extending along the length of
the structural frame spaced from and parallel to the first track;
and a top drive carriage assembly comprising at least one sprocket
arrangement operatively engaged with one of the first track and the
second track, wherein the first track and the second track each
comprise a plurality of bushings equally spaced apart and attached
to spaced apart track plates, and the at least one sprocket
arrangement comprises a plurality of teeth configured to
operatively engage the plurality of bushings such that the top
drive carriage assembly moves along the length of the structural
frame of the mast.
2. The drilling rig of claim 1, wherein each of the plurality of
bushings is attached to the spaced apart track plates by a bolt and
nut arrangement.
3. The drilling rig of claim 1, wherein each of the first track and
the second track further comprises wear plates positioned adjacent
to the plurality of bushings to prevent wear on the track
plates.
4. The drilling rig of claim 1, wherein at least one first roller
configured to move with the top drive carriage assembly is provided
adjacent to outer edges of the spaced apart track plates of the
first track and at least one second roller configured to move with
the top drive carriage assembly is provided adjacent to outer edges
of the spaced apart track plates of the second track.
5. The drilling rig of claim 1, wherein the at least one sprocket
arrangement is driven by a planetary gear arrangement driven by a
hydraulic motor.
6. The drilling rig of claim 1, wherein the top drive carriage
assembly includes four sprocket arrangements.
7. The drilling rig of claim 6, wherein two of the sprocket
arrangements are operatively engaged with the first track and two
of the sprocket arrangements are operatively engaged with the
second track.
8. The drilling rig of claim 6, wherein each of the sprocket
arrangements is driven by a separate planetary gear arrangement
driven by a hydraulic motor.
9. The drilling rig of claim 8, further comprising a control panel
having four on/off switches, a joystick control, and potentiometer
knob for controlling four hydraulic pumps.
10. The drilling rig of claim 1, wherein the sprocket arrangement
is manufactured using a water-jet technique.
11. A drive mechanism for a top drive carriage assembly of a
drilling rig comprising: a track comprising a plurality of bushings
equally spaced apart and attached to spaced apart track plates; and
at least one sprocket arrangement operatively engaged with the
track, wherein the at least one sprocket arrangement comprises a
plurality of teeth configured to operatively engage the plurality
of bushings such that the sprocket assembly moves along the
track.
12. The drive mechanism of claim 11, wherein each of the plurality
of bushings is attached to the spaced apart track plates by a bolt
and nut arrangement.
13. The drive mechanism of claim 11, wherein the track further
comprises wear plates positioned adjacent to the plurality of
bushings to prevent wear on the track plates.
14. A method of drilling comprising: providing a drilling rig
comprising: a mast base; a mast comprising a structural frame
extending from the mast base, the structural frame including a
first track extending along the length of the structural frame and
a second track extending along the length of the structural frame
spaced from and parallel to the first track, the first track and
the second track each comprises a plurality of bushings equally
spaced apart and attached to spaced apart track plates; a top drive
carriage assembly comprising at least one sprocket arrangement
operatively engaged with one of the first track and the second
track; and the at least one sprocket arrangement comprises a
plurality of teeth configured to operatively engage the plurality
of bushings such that the top drive carriage assembly moves along
the length of the structural frame of the mast; raising the mast
onto the mast base such that it is substantially perpendicular to a
surface; coupling an upper end of a drill string having a drill bit
at a lower end thereof to a top drive drill head of the top drive
carriage assembly; and providing a rotational drive force to the
drill string by the top drive drill head such that the drill bit is
rotated to bore into the earth.
15. The method of claim 14, wherein each of the plurality of
bushings is attached to the spaced apart track plates by a bolt and
nut arrangement.
16. The method of claim 14, wherein each of the first track and the
second track further comprises wear plates positioned adjacent to
the plurality of bushings to prevent wear on the track plates.
17. The method of claim 14, wherein at least one first roller
configured to move with the top drive carriage assembly is provided
adjacent to outer edges of the spaced apart track plates of the
first track and at least one second roller configured to move with
the top drive carriage assembly is provided adjacent to outer edges
of the spaced apart track plates of the second track.
18. The method of claim 14, wherein the at least one sprocket
arrangement is driven by a planetary gear arrangement driven by a
hydraulic motor.
19. The method of claim 14, wherein the top drive carriage assembly
includes four sprocket arrangements.
20. The method of claim 19, wherein two of the sprocket
arrangements are operatively engaged with the first track and two
of the sprocket arrangements are operatively engaged with the
second track.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Patent Application No. 61/148,582 entitled "Track and Sprocket
Drive for Drilling" filed Jan. 30, 2009, which is hereby
incorporated by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates, in general, to a drilling rig
primarily for use in gas drilling and, more particularly, to a
drive mechanism for a carriage of the drilling rig.
[0004] 2. Description of Related Art
[0005] A vertical drilling rig is commonly used in oil, gas, and
coal bed methane well drilling. Conventional vertical drilling rigs
use heavy drill pipe and/or drill collars in order to exert
downward force on the drill bit as it enters the earth's surface
and begins the well bore.
[0006] Vertically drilling an oil or gas well begins with the step
of positioning a drill string terminating with a drill bit and
rotating the drill string such that the drill bit bores into the
ground or into the seabed, in the case of offshore drilling, until
it reaches a predetermined depth or penetrates a petroleum-bearing
or gas-bearing geological formation. The components of the drill
string, such as the drill pipe and/or drill collars, are threaded
for interconnection. The uppermost length of drill pipe in the
drill string is connected to a top drive positioned on a carriage.
As the drill bit advances and the top of the drill string
approaches the working platform or drill floor of the drilling rig,
additional lengths of drill pipe must be added to the drill string
in order to advance the well further into the ground. This is
accomplished by temporarily supporting the top of the drill string
near the drill floor level, disconnecting the top drive from the
top of the drill string, and then lifting a new section of drill
pipe into position using the rig's elevating system and screwing it
into the top of the drill string. The top drive is then reconnected
to the drill string, and drilling operations resume until it is
again necessary to add drill pipe. In addition, as the drill bit of
the vertical drilling rig drills deeper below the earth's surface,
it is sometimes necessary to apply force in the opposite direction
of the drilling direction (pull-back force) in order to prevent
placing too much weight on the drill bit and causing damage to or
failure of the drill bit. This is accomplished by using the top
drive.
[0007] It is also known in the art to drill oil, gas, and methane
wells in a vertical direction initially and then deviate or turn
the well bore in increments toward a horizontal direction as the
drill bit reaches the target formation. The bore hole is then
continued in the horizontal direction for a distance. This method
exposes a greater volume of the oil, gas, or methane producing
formation to the well bore and produces a higher and longer
producing well.
[0008] In order to convert a vertical drilling rig to accomplish
the combination vertical-horizontal drilling, it is necessary that
the vertical drilling rig include a top drive to provide rotational
force to the drill pipe, rather than a rotary table and Kelly bar.
Top drive units are typically driven by either hydraulic or
electric power. The top drive is supported by the rig's main hoist
and moves downward along with the drill string as drilling
progresses. The top drive also provides thrust and pull-back forces
which are needed while drilling in the horizontal direction. The
top drive typically travels along vertical guide rails built into
the mast of the rig superstructure. However, the distances of the
horizontal runs produced by conventional devices and methods are
limited by the capability of the top drive to apply thrust and
pull-back forces to the drill pipe. The diameters of the horizontal
runs are also limited by the ability to apply thrust and pull-back
forces to the drill pipe. There are several known drive mechanisms
for allowing the top drive to travel along the mast of a rig
superstructure, thereby applying thrust and pull-back forces to the
drill pipe. However, each of these known drive mechanisms suffers
from various deficiencies.
[0009] For instance, U.S. Pat. No. 7,318,491 to Riel discloses a
modified horizontal directional drilling (HDD) assembly. The
modified HDD assembly includes a rotary and carriage assembly. The
rotary and carriage assembly is adapted to move along a thrust
frame and provide thrust force, pull-back force, and rotational
torque to a drill pipe or casing. The rotary and carriage assembly
is driven by a positive rack and pinion carriage system. Such rack
and pinion systems generally lose efficiency as the gear teeth and
guide system wear. The pressure angle of the gear teeth results in
forces acting to spread the pinion away from the rack. These forces
must be counteracted by the bearings on the pinion drive, as well
as by any guide system used to maintain distance between pinion
shaft and rack. As the guide system and gear teeth wear, the
effective pressure angle typically increases, thereby increasing
the load on the pinion bearings and guide system. The increased
load results in decreased efficiency due to increased drag. In
addition, if one of the teeth in the rack becomes inoperative due
to wear, the entire rack may need to be replaced.
[0010] United States Patent Application Publication No.
2007/0246264 to Folk is directed to a worm and collar drive
drilling rig. The drilling rig includes a substructure and a mast.
The mast includes a worm drive which is a driveshaft having a
helical groove cut into its surface. A collar having means for
engaging the worm drive is driven longitudinally along the length
of the worm drive by rotation of the worm drive. In its simplest
form, the collar may be a nut having an internal thread
complementary to the worm drive helical groove. The collar includes
a plurality of rollers disposed internally which engage the worm
drive. The rollers are arranged in a helical manner within the
collar, which matches the helical pitch of the worm drive. Each
roller includes a shaft and a head which is rotatably supported on
the shaft by a suitable bearing set. The roller shaft passes
through an opening in the collar and is secured by a nut. However,
this system suffers from various deficiencies. For instance, it is
complex and expensive to manufacture. In addition, if the worm
drive malfunctions or wears out, it is difficult to replace.
[0011] Accordingly, a need exists for a drive system to allow a top
drive carriage to travel along the mast of a drilling rig in an
efficient manner and that allows for easy replacement and repair of
damaged parts.
SUMMARY OF THE INVENTION
[0012] An object of the present invention is to provide a drive
system for a top drive carriage that precisely and efficiently
moves the top drive carriage along a mast. The mast may include
multiple sections that are easily assembled in the field. Another
object of the present invention is to guide the top drive carriage
without the use of additional guide rails. In addition, it is a
further object of the present invention to provide a drive system
for a top drive carriage that allows for easy replacement and
repair of damaged parts.
[0013] The present invention is directed to a drilling rig that
includes a mast base and a mast having a structural frame extending
from the mast base. The structural frame includes a first track
extending along the length of the structural frame and a second
track extending along the length of the structural frame spaced
from and parallel to the first track. The drilling rig also
includes a top drive carriage assembly having at least one sprocket
arrangement operatively engaged with one of the first track and the
second track. The first track and the second track each include a
plurality of bushings equally spaced apart and attached to spaced
apart track plates. The at least one sprocket arrangement has a
plurality of teeth configured to operatively engage the plurality
of bushings such that the top drive carriage assembly moves along
the length of the structural frame of the mast.
[0014] Each of the plurality of bushings may be attached to the
spaced apart track plates by a bolt and nut arrangement. In
addition, each of the first track and the second track may further
include wear plates positioned adjacent to the plurality of
bushings to prevent wear on the track plates. At least one first
roller configured to move with the top drive carriage assembly may
be provided adjacent to an outer edge of the spaced apart track
plates of the first track, and at least one second roller
configured to move with the top drive carriage assembly may be
provided adjacent to an outer edge of the spaced apart track plates
of the second track.
[0015] The at least one sprocket arrangement may be driven by a
planetary gear arrangement driven by a hydraulic motor. The top
drive carriage assembly may include four sprocket arrangements. Two
of the sprocket arrangements may be operatively engaged with the
first track and two of the sprocket arrangements may be operatively
engaged with the second track. Each of the sprocket arrangements
may be driven by a separate planetary gear arrangement driven by a
hydraulic motor. The sprocket arrangement may be manufactured using
a water-jet technique. The drilling rig may further include a
control panel having speed control mechanisms for controlling the
hydraulic motors.
[0016] In addition, the present invention is also directed to a
drive mechanism for a top drive carriage assembly of a drilling
rig. The drive mechanism includes a track having a plurality of
bushings equally spaced apart and attached to spaced apart track
plates; and at least one sprocket arrangement operatively engaged
with the track. The at least one sprocket arrangement includes a
plurality of teeth configured to operatively engage the plurality
of bushings such that the sprocket assembly moves along the
track.
[0017] Each of the plurality of bushings may be attached to the
spaced apart track plates by a bolt and nut arrangement. In
addition, the track may further include wear plates positioned
adjacent to the plurality of bushings to prevent wear on the track
plates. The at least one sprocket arrangement may be driven by a
planetary gear arrangement driven by a hydraulic motor. The
sprocket arrangement may be manufactured using a water jet
technique.
[0018] The present invention is also directed to a method of
drilling. The method includes the step of providing a drilling rig.
The drilling rig includes a mast base and a mast having a
structural frame extending from the mast base. The structural frame
includes a first track extending along the length of the structural
frame and a second track extending along the length of the
structural frame spaced from and parallel to the first track. The
drilling rig also includes a top drive carriage assembly having at
least one sprocket arrangement operatively engaged with one of the
first track and the second track. The first track and the second
track each include a plurality of bushings equally spaced apart and
attached to spaced apart track plates. The at least one sprocket
arrangement has a plurality of teeth configured to operatively
engage the plurality of bushings such that the top drive carriage
assembly moves along the length of the structural frame of the
mast. The method also includes the steps of: raising the mast onto
the mast base such that it is substantially perpendicular to a
surface; coupling an upper end of a drill string having a drill bit
at a lower end thereof to a top drive drill head of the top drive
carriage assembly; and providing a rotational drive force to the
drill string by the top drive drill head such that the drill bit is
rotated to bore into the earth.
[0019] Each of the plurality of bushings may be attached to the
spaced apart track plates by a bolt and nut arrangement. In
addition, each of the first track and the second track may further
include wear plates positioned adjacent to the plurality of
bushings to prevent wear on the track plates. At least one first
roller configured to move with the top drive carriage assembly may
be provided adjacent to an outer edge of the spaced apart track
plates of the first track, and at least one second roller
configured to move with the top drive carriage assembly may be
provided adjacent to an outer edge of the spaced apart track plates
of the second track. The at least one sprocket arrangement may be
driven by a planetary gear arrangement driven by a hydraulic motor.
The top drive carriage assembly may include four sprocket
arrangements. Two of the sprocket arrangements may be operatively
engaged with the first track and two of the sprocket arrangements
may be operatively engaged with the second track.
[0020] These and other features and characteristics of the present
invention, as well as the methods of operation and functions of the
related elements of structures, will become more apparent upon
consideration of the following description and the appended claims
with reference to the accompanying drawings, all of which form a
part of this specification, wherein like reference numerals
designate corresponding parts in the various figures. As used in
the specification and the claims, the singular form of "a", "an",
and "the" include plural referents unless the context clearly
dictates otherwise.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is a perspective view of a drilling rig having a top
drive carriage assembly driven by a track and sprocket drive
mechanism in accordance with the present invention;
[0022] FIG. 2 is a front plan view of a portion of the drilling rig
of FIG. 1;
[0023] FIG. 3 is a portion of the front plan view of the drilling
rig of FIG. 1 enlarged for magnification purposes;
[0024] FIG. 4 is a cross-sectional view of the top drive carriage
assembly taken along line 4-4 in FIG. 2;
[0025] FIG. 5 is a portion of the view of FIG. 4 illustrating a
track of the track and sprocket drive mechanism enlarged for
magnification purposes;
[0026] FIG. 6 is a schematic side view of the track and sprocket
drive mechanism in accordance with the present invention; and
[0027] FIG. 7 is a side view of an alternative embodiment of a
drilling rig in accordance with the present invention.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
[0028] For purposes of the description hereinafter, the terms
"upper", "lower", "right", "left", "vertical", "horizontal", "top",
"bottom", "lateral", "longitudinal", and derivatives thereof shall
relate to the invention as it is oriented in the drawing figures.
However, it is to be understood that the invention may assume
various alternative variations, except where expressly specified to
the contrary. It is also to be understood that the specific devices
illustrated in the attached drawings, and described in the
following specification are simply exemplary embodiments of the
invention. Hence, specific dimensions and other physical
characteristics related to the embodiments disclosed herein are not
to be considered as limiting.
[0029] With reference to FIG. 1, a drilling rig, denoted generally
as reference numeral 1, that includes a highly controllable top
drive carriage assembly 3 is illustrated. Drilling rig 1 may be
used for vertical drilling, horizontal drilling, combination
vertical/horizontal drilling, directional drilling, and various
other drilling applications. Drilling rig 1 includes a mast base 5
and a mast 7 having a structural frame 9 extending from mast base
5. Mast base 5 and mast 7 are desirably transported to a drilling
site on a flat-bed truck or any other suitable means for
transportation. In addition, mast base 5 is anchored to the ground
at the drilling site using any suitable anchoring means as are
known in the art.
[0030] Structural frame 9 includes a first track 11 and a second
track 13 extending along a length L thereof. First track 11 and
second track 13 are spaced a distance D from each other and are
positioned parallel to each other. As shown in FIGS. 5 and 6, first
track 11 and second track 13 each include a plurality of bushings
15 equally spaced apart and attached to spaced apart track plates
17. Each of the plurality of bushings 15 has a hollow, cylindrical
shape having a passage 16 therethrough and is manufactured from
hardened steel. However, this is not to be construed as limiting
the present invention as the bushings 15 may be of any suitable
shape and may be manufactured from any material having sufficient
durability.
[0031] Each of the plurality of bushings 15 is attached to the
spaced apart track plates 17 by a bolt and nut arrangement 19 that
passes through holes (not shown) provided in track plates 17 and
through passage 16 in bushing 15. In addition, first track 11 and
second track 13 may further include wear plates 21 positioned
adjacent to the plurality of bushings 15 to prevent wear on track
plates 17 as will be discussed in greater detail hereinafter.
Bushings 15 are attached to track plates 17 in a pattern of motion
desired. As shown in the figures, this pattern of motion is linear.
However, this is not to be construed as limiting the present
invention as the pattern may be non-linear depending on the
application.
[0032] With reference to FIGS. 2 and 3 and with continuing
reference to FIG. 1, drilling rig 1 also includes top drive
carriage assembly 3. Top drive carriage assembly 3 includes a body
23 having a top drive drill head 25 and at least one sprocket
arrangement 27 positioned thereon. Desirably and as shown in FIGS.
1 and 2, top drive carriage assembly 3 includes four sprocket
arrangements 27A-27D. However, this is not to be construed as
limiting the present invention as any suitable number of sprocket
arrangements suitable to allow top drive carriage assembly 3 to
travel along length L of mast 7 may be utilized.
[0033] Top drive drill head 25 is configured to be connected to the
top of a drill string (not shown). Once a drill string is connected
to top drive drill head 25, top drive drill head 25 provides a
rotational drive force thereto. The rotational drive force is
provided by a rotary hydraulic or electric motor (not shown).
[0034] In addition, top drive carriage assembly 3 is configured to
move along length L of mast 7 by means of the four sprocket
arrangements 27A-27D. Two of the sprocket arrangements 27A, 27B may
be operatively engaged with first track 11 and two of the sprocket
arrangements 27C, 27D may be operatively engaged with second track
13. More specifically, each of the sprocket arrangements 27A-27D
has a plurality of teeth 29 configured to operatively engage the
plurality of bushings 15 of either first track 11 or second track
13. The plurality of teeth 29 are formed in sprocket arrangements
27A-27D such that they engage the plurality of bushings 15 with a
high degree of precision as shown in FIG. 6. Each sprocket
arrangement 27 includes a round surface to one side of teeth 29
that acts as a roller to maintain a constant distance from the
center of sprocket arrangement 27 to the track 11 or 13 with which
the sprocket is engaged. Sprocket arrangements 27A-27D may be
manufactured using a water-jet technique or any other suitable
technique.
[0035] With reference to FIG. 4, and with continuing reference to
FIGS. 1-3, each of sprocket arrangements 27A-27D is driven by a
planetary drive assembly 31. Planetary drive assembly 31 includes a
planetary gear arrangement 33, a hydraulic motor 35, and a brake
37. Each sprocket arrangement 27A-27D is driven by a separate
planetary gear arrangement 33 driven by a hydraulic motor 35, such
that sprocket arrangement 27A, 27B, 27C, or 27D rotates and
operatively engages the plurality of bushings 15. This rotation of
sprocket arrangements 27A-27D allows top drive carriage assembly 3
to move up and down along the length L of structural frame 9 of
mast 7. As sprocket arrangements 27A-27D engage and move along the
plurality of bushings 15, sprocket arrangements 27A-27D ride
against wear plates 21. This prevents wear on track plates 17. Wear
plates 21 and the bushings 15 are adapted to be easily removable
and replaceable when either the wear plates 21 or bushings 15 are
worn or fail.
[0036] In addition, since each sprocket arrangement 27A-27D is
driven by a two speed planetary drive assembly 31 and a hydraulic
motor 35 capable of smooth operation over a wide range of speeds,
the drive mechanism of the present invention is highly
controllable. A control panel 39 is provided at mast base 5. A
canopy 40 is provided over control panel 39 to protect an operator
from falling objects. Control panel 39 includes on/off switches 41
for each of four electrically-controlled hydraulic pumps (not
shown) used to provide hydraulic power to drive the hydraulic
motors 35. Any combination of positions of on/off switches 41 for
the four electrically-controlled hydraulic pumps may be used to
reduce hydraulic oil flow for more control, increase hydraulic oil
flow for more speed, and/or avoid using a pump that is in need of
repair. In addition, a potentiometer knob 43 and joystick control
(not shown) are provided to control the speed and direction of
hydraulic motors 35, thereby providing control of the speed of
rotation and the direction of rotation of each of sprocket
arrangements 27A-27D. The joystick control overrides potentiometer
knob 43. This allows a user to set potentiometer knob 43 to a
desired drilling speed allowing for hands-free operation, and then
use the joystick control to override potentiometer knob 43 and take
manual control of the drilling process. Accordingly, control panel
39 allows for precise control of the movement of top drive carriage
assembly 3 along the length L of structural frame 9 of mast 7.
[0037] Top drive carriage assembly 3 further includes at least one,
and desirably two, rollers 45 configured to move with top drive
carriage assembly 3. Roller 45 is provided adjacent to an outer
edge of the spaced apart track plates 17 of first track 11. Also,
at least one, and desirably two, rollers 47 configured to move with
top drive carriage assembly 3 are provided adjacent to an outer
edge of spaced apart track plates 17 of second track 13. Rollers 45
and 47 are provided to prevent bowing so that the two track plates
17 of each of first track 11 and second track 13 remain parallel
and equidistant to each other. In an alternative embodiment,
rollers 45 and 47 can be replaced with additional sprocket
arrangements 27 such that sprocket arrangements 27 are provided on
both sides of first track 11 and second track 13. This alternative
embodiment is illustrated in FIG. 7. First track 11 and second
track 13 may be arranged differently to provide for a smaller
overall mast dimension if desired.
[0038] In operation, mast 7 is raised onto mast base 5 such that it
is substantially perpendicular to a surface of the ground. Next, an
upper end of a drill string having a drill bit at a lower end
thereof is coupled to top drive drill head 25 of top drive carriage
assembly 3. Top drive drill head 25 provides a rotational drive
force to the drill string such that the drill bit may be rotated to
bore into the earth. The present invention may be used for several
drilling methods including, but not limited to, rotary drilling by
rotating the entire string, rotary hammer drilling by rotating the
entire string, and directional drilling with a down-hole motor by
rotating or holding the entire string. In addition, the drill
string may be pushed downward to apply force to the drill bit by a
downward movement of top drive carriage assembly 3 along first
track 11 and second track 13 by the rotational engagement of
sprocket arrangements 27A-27D with bushings 15 of first track 11
and second track 13. Once the entire length of the drill string has
been bored into the earth, the upper end of the drill string is
disengaged from top drive drill head 25 and top drive carriage
assembly 3 is moved up along first track 11 and second track 13 by
reversing the direction of rotation of sprocket arrangements
27A-27D. When top drive carriage assembly 3 reaches a desired
height along length L of mast 7, a new section of drill pipe is
coupled at an upper end to top drive drill head 25 and at a lower
end to the upper end of the drill string. Top drive drill head 25
provides a rotational drive force and/or control of downward
movement and force to the newly added piece of drill pipe such that
the drill bit bores into the earth at the desired rate. Downward
movement of top drive carriage assembly 3 along first track 11 and
second track 13 is provided by the rotational engagement of
sprocket arrangements 27A-27D with bushings 15 of first track 11
and second track 13. This process is then repeated, with new pieces
of drill pipe being added to the drill string until the desired
drilling depth is reached. The drilling rig of the present
invention as shown in the figures allows for thirty (30) foot long
pieces of drill pipe to be added to the drill string during each
operation.
[0039] Accordingly, the present invention provides a drive
mechanism for a top drive carriage assembly that cures the
deficiencies of prior art drive mechanisms. For instance, the
present invention provides a drive mechanism that is easier and/or
cheaper to manufacture than a typical rack and pinion system. In
addition, the present invention provides a drive mechanism for a
top drive carriage assembly that is easier to service compared to a
gear rack of a conventional rack and pinion drive mechanism due to
size wearing elements and the ability to replace one bushing at a
time rather than an entire gear rack.
[0040] Although the invention has been described in detail for the
purpose of illustration based on what is currently considered to be
the most practical and preferred embodiments, it is to be
understood that such detail is solely for that purpose and that the
invention is not limited to the disclosed embodiments, but, on the
contrary, is intended to cover modifications and equivalent
arrangements that are within the spirit and scope of the appended
claims. For example, it is to be understood that the present
invention contemplates that, to the extent possible, one or more
features of any embodiment can be combined with one or more
features of any other embodiment.
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