U.S. patent application number 12/138891 was filed with the patent office on 2009-01-08 for pdc cutter with oval cross-section.
This patent application is currently assigned to BAKER HUGHES INCORPORATED. Invention is credited to William H. Sherwood, JR..
Application Number | 20090008155 12/138891 |
Document ID | / |
Family ID | 40220578 |
Filed Date | 2009-01-08 |
United States Patent
Application |
20090008155 |
Kind Code |
A1 |
Sherwood, JR.; William H. |
January 8, 2009 |
PDC CUTTER WITH OVAL CROSS-SECTION
Abstract
A drag bit having cutting elements, wherein the cross section of
the cutting elements is an oval shape, wherein in one embodiment
the major axis is perpendicular to the surface of the drag bit
blade. A method is also included, wherein the method comprises
using a milling bit having an oval cross section that thereby
produces pockets in the drag bit blades for receiving the oval
shaped cutting elements. Use of the oval bit also results in a half
oval formed at the closed end of the pocket.
Inventors: |
Sherwood, JR.; William H.;
(Spring, TX) |
Correspondence
Address: |
Bracewell & Giuliani LLP
P.O. Box 61389
Houston
TX
77208-1389
US
|
Assignee: |
BAKER HUGHES INCORPORATED
Houston
TX
|
Family ID: |
40220578 |
Appl. No.: |
12/138891 |
Filed: |
June 13, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60947591 |
Jul 2, 2007 |
|
|
|
Current U.S.
Class: |
175/431 ;
76/108.2 |
Current CPC
Class: |
E21B 10/5673 20130101;
E21B 10/55 20130101; E21B 10/573 20130101; E21B 10/54 20130101 |
Class at
Publication: |
175/431 ;
76/108.2 |
International
Class: |
E21B 10/43 20060101
E21B010/43 |
Claims
1. A drag bit for use in earth boring operations comprising: a drag
bit body having a cutting surface on one end and a drill string
connection on an opposite end; a blade formed on the bit body
cutting surface; and a cutting element provided with the blade, the
cutting element having an oval cutting face perimeter.
2. The drag bit of claim 1, further comprising a cutter pocket
formed in the blade correspondingly shaped to the cutting element,
the cutting element disposed in the cutter pocket.
3. The drag bit of claim 1, further comprising a plurality of
blades on the bit body and a plurality of cutting elements on the
blades.
4. The drag bit of claim 1 further comprising a PDC insert affixed
to the cutting face.
5. The drag bit of claim 1 further comprising a cutting element
having an oval shaped perimeter on the drag bit body between the
cutting surface and the drill string connection.
6. The drag bit of claim 1 further comprising a drill string having
an upper end and a lower end, the drill string lower end affixed to
the drill string connection and a top drive connected to the drill
string upper end.
7. The drag bit of claim 1, wherein the cutting face surface
includes an elongate section, wherein the elongate section oriented
substantially perpendicular to the blade.
8. A method of forming a cutter pocket on a blade of a drag bit
used in earth boring operations, the drag bit having a body, the
blade extending from the bit body and having a top surface and
sides surfaces, the side surfaces extending from the bit body to
the top surface, the method comprising: activating a milling device
having an oval shaped milling bit, thereby rotating the oval shaped
milling bit; positioning the oval shaped milling bit adjacent the
blade at a location where the side surface and top surface
converge; and forming a cutter pocket having an oval shaped
perimeter by moving the activated oval shaped milling bit through
the blade.
9. The method of claim 8, further comprising orienting the milling
bit normal to the blade top surface.
10. The method of claim 8 wherein a shaft connects the oval shaped
milling bit to the milling device, the method further comprising
positioning the milling bit shaft above the blade top surface
before moving the activated oval shaped milling bit through the
blade.
11. The method of claim 8 wherein the back end of pocket is oval
shaped.
12. The method of claim 8 further comprising forming a multiplicity
of pockets
13. The method of claim 8 further comprising adding an oval shaped
cutting element to the cutter pocket.
14. The method of claim 8 wherein the milling bit width exceeds its
length.
15. The method of claim 8, wherein the milling bit length exceeds
its width.
16. The method of claim 8, wherein the drag bit comprises a
multiplicity of blades on the bit body thereby defining spaces
between adjacent blades, the method further comprising disposing
the oval shaped milling bit within the space between adjacent
blades.
17. The method of claim 8 further comprising including the drag bit
with a drilling system and forming a wellbore.
Description
RELATED APPLICATIONS
[0001] This application claims priority to and the benefit of
co-pending U.S. Provisional Application Ser. No. 60/947,591, filed
Jul. 2, 2007, the full disclosure of which is hereby incorporated
by reference herein.
BACKGROUND
[0002] 1. Field of Invention
[0003] The disclosure herein relates to contoured cutting teeth for
use with a drilling bit. More specifically, the present disclosure
concerns oval shaped cutting teeth disposed in a correspondingly
formed pocket, wherein the pocket is situated on the cutting
surface of a drag bit. The present disclosure also concerns a
method for forming the pockets on the face of a drill bit.
[0004] 2. Description of Prior Art
[0005] With respect to FIG. 1, an example of a drag bit 10 is shown
in a perspective view. The drag bit 10 shown in FIG. 1 includes a
body 13 on one end connectable to a drilling system (not shown)
through a threaded connection 11 and an upper surface 12 on the
opposite end. Formed on the upper surface 12 of the bit 10 are a
series of blades 14. The blades comprise a raised portion of
material having a generally rectangular cross-section that extends
roughly from the center portion of the surface 12 and
longitudinally extend radially outward from the surface and down
along a side of the bit 10. Pockets 16 are formed on the upper
surface of the blade, wherein the respective axes of the pockets
are generally parallel with other pockets on the individual blade.
Typically, the pockets comprise a hollowed out trough portion of
the upper surface of the blade 14, wherein the pockets are formed
to receive a cutting element 18 therein. The cutting elements can
be attached in any number of ways, such as welding and brazing or
other attachment means. The cutting element has a generally
cylindrical shape with a cutting face on one end rounded on its
other end. It is well known in the prior art to add polycrystalline
diamond compact, i.e., PDC, on the face of the cutting element 18.
The cutting element body is typically formed of a relatively hard
material such as sintered tungsten carbide. The PDC layer may be
mounted directly on the mounting body or on an intermediate carrier
also generally made from a sintered tungsten carbide.
[0006] The bit body 10 is usually comprised of either a tungsten
carbide matrix or various forms of steel. When the body is made of
steel, the pocket receiving the stud is generally in the shape of a
cylinder to receive the cylindrically shaped cutting element
18.
[0007] Drilling systems typically utilize the weight on bit to
press down into the rock; the weight on bit pressing on the rock
combined with the torque crushes the rock to bore through the rock.
Continued turning of the drill string pushes the teeth through the
rock by the combined forces of the weight on bit and the
torque.
SUMMARY OF INVENTION
[0008] The present disclosure concerns a drag bit and a method for
creating a drag bit. In one embodiment, the drag bit comprises a
blade on its cutting face, with at least one pocket formed on the
blade. The pocket has a cutting element disposed within, wherein
the cutting element has an oval cross section. The terminal end of
the pocket and the back end of the cutting element may have
corresponding shapes resembling a half portion of an oval.
[0009] A method as included herein for forming the pockets on the
blade of the drag bit. The method involves utilizing a milling
element comprising an oval shaped end and shaft connecting the end
to a milling device. The oval shaped end is used for forming
pockets on the blade surface of the cutting bit.
BRIEF DESCRIPTION OF DRAWINGS
[0010] Some of the features and benefits of the present invention
having been stated, others will become apparent as the description
proceeds when taken in conjunction with the accompanying drawings,
in which:
[0011] FIG. 1 is a perspective view of a traditional drag bit.
[0012] FIGS. 2a and 2b provide a perspective view and a side view
of a cutting element of the present disclosure.
[0013] FIG. 3 illustrates a perspective view of a cutting element
of the present disclosure combined with a drag bit.
[0014] FIG. 4 illustrates a side view of an oval end mill used for
creating pockets in a drag bit.
[0015] FIG. 5 illustrates a cross-sectional view of a drag bit
blade having oval shaped pockets formed therein.
[0016] FIG. 6 is a perspective view of milling devices forming
cutter pockets.
[0017] FIG. 7 is a side partial sectional view of a drilling system
having a drag bit with oval shaped cutting elements forming a
wellbore.
[0018] While the invention will be described in connection with the
preferred embodiments, it will be understood that it is not
intended to limit the invention to that embodiment. On the
contrary, it is intended to cover all alternatives, modifications,
and equivalents, as may be included within the spirit and scope of
the invention as defined by the appended claims.
DETAILED DESCRIPTION OF INVENTION
[0019] The present invention will now be described more fully
hereinafter with reference to the accompanying drawings in which
embodiments of the invention are shown. This invention may,
however, be embodied in many different forms and should not be
construed as limited to the illustrated embodiments set forth
herein; rather, these embodiments are provided so that this
disclosure will be through and complete, and will fully convey the
scope of the invention to those skilled in the art. Like numbers
refer to like elements throughout.
[0020] It is to be understood that the invention is not limited to
the exact details of construction, operation, exact materials, or
embodiments shown and described, as modifications and equivalents
will be apparent to one skilled in the art. In the drawings and
specification, there have been disclosed illustrative embodiments
of the invention and, although specific terms are employed, they
are used in a generic and descriptive sense only and not for the
purpose of limitation. Accordingly, the invention is therefore to
be limited only by the scope of the appended claims.
[0021] With reference now to FIG. 2a a perspective view of one
embodiment of a cutting element 20 in accordance with the present
disclosure is provided. In this embodiment, the cutting element 20
includes a body 21 a cutting face 22 on its front portion. The body
21 cross section, the face 22, and the face 22 perimeter have a
generally oval configuration. Lines D.sub.1 and D.sub.2 are
provided on the cutting face 22 respectively illustrating prolate
and oblate lengths, where the prolate (or elongate) length exceeds
the oblate length. Although the oval face 22 as shown in FIG. 2a is
substantially symmetric about both D.sub.1 and D.sub.2, the oval
shape as disclosed herein includes ovals symmetric about one of
either D.sub.1 or D.sub.2, or asymmetric about both D.sub.1 and
D.sub.2.
[0022] As shown, the face 22 is largely planar and substantially
perpendicular to the axis A of the cutting element 20.
Additionally, the end portion 24 of the cutting element 20 is shown
having a half oval shape. More specifically, as can be seen in the
side view of FIG. 2b, the cutting element 20 of this embodiment has
an end 24 wherein the terminal section of the end is oval. Other
embodiments of this cutting element may include hemispherical or
one having a flat face. It should be pointed out that the half oval
contour of the end 24 of the cutting element 20 is not limited to
the dimensions shown in the figure, but can include any number of
oval shapes with an infinite number of combinations of major axis
and minor axis.
[0023] An insert 26 is shown in side view optionally disposed on
the entire surface of the face 22. The insert 26 may comprise any
number of hard or super hard, materials typically used in
conjunction with cutting elements of earth boring drag bits.
Examples include PDC material, sintered tungsten carbide, and any
other hard or super hard material useful in drag bit
applications.
[0024] FIG. 3 is a perspective view of a portion of a drag bit 25
having an embodiment of the cutting element 20 of FIGS. 2a and 2b.
The drag bit 25 comprises a cutting blade 28 extending from a bit
body 27 thereby defining a cutting face 29 on the forward and
rearward sides of the blade 28. A top surface 33 extends between
the respective upper terminal ends of the cutting face 29. The
cutting face 29 is illustrated in FIG. 3 as substantially
perpendicular to the bit body 27, however the cutting face 29 can
instead be oblique to the bit body 27. Additionally, the top
surface 33 is shown as parallel to the bit body 27 and
substantially planar, however the top surface 33 is not limited to
this configuration. The blade 28 includes a pocket 30 formed
thereon correspondingly contoured to the cutting element 20 oval
shape. Securing the cutting element 20 in the pocket 30 may be done
in any number of methods, including brazing, welding, and
cementing.
[0025] In FIG. 4, a side view of a mill bit 32 is illustrating that
includes a tip 34 having a largely frusto-oval cross section. For
the purposes of discussion herein, a frusto-oval means oval shaped
along at least a portion of the member, the remaining portion of
the member can be truncated or have a non-oval shape. In the
embodiment of FIG. 4, the oval cross section of the tip 34
truncates where it attaches to a shaft 36. Optionally however, the
present disclosure includes embodiments wherein the tip 34 is oval,
frusto-oval, egg shaped, elliptical, frusto-elliptical, or entirely
oval. The shaft 36 is coupled with a milling machine thereby
providing rotational energy for engaging the tip 34. Accordingly,
the pockets 30 of FIG. 5 may be formed using the oval shaped tip 34
of the milling device of this disclosure.
[0026] FIG. 6 provides a perspective view a milling operation using
the mill bit 32. Here a pocket is formed on a drag bit by
energizing or activating the milling device 31 thereby rotating the
mill bit 32. The milling device 31 and rotating mill bit 32 are
disposed adjacent the blade to be cut and positioned proximate to
where the cutter pocket 30 is to be formed. The rotating mill bit
32 is then urged into the blade 28 and across the top surface 33 to
form the pocket 30. Preferably the mill bit 32 is oriented parallel
to the cutting face 29 of the blade 28. Cutting across the top
surface 33 rather than parallel to the top surface 33 allows mill
bit 32 insertion into the space 37 separating adjacent blades 28.
While rotating the mill bit 32, the milling device 31 urges the
mill bit 32 longitudinally transverse to the surface of the cutting
face 29 until a desired length of pocket 30 is formed within the
upper surface of the blade 28. The oval shape of the tip 34 thereby
not only provides an oval cross section, but also forms a half oval
in the closed end of the pocket 30.
[0027] FIG. 6 illustrates both the milling device 31 with the oval
mill bit 32 and a currently used milling tool 3 with an associated
bit 4. One of the advantages of using the mill bit 32 having the
oval end piece over current methods of manufacturing is the
difference in milling bit orientation. The current method of
milling cutter pockets orient the milling bit 4 and milling tool 3
parallel to the blades. This involves reaching the bit 4 past a
blade that is forward of the blade being cut with the milling tool.
The milling bit 4 thus needs to be sufficiently long to clear the
forward blade while cutting. Reaching past the forward blade
requires a longer than necessary milling bit which results in a
weak tooling because of the extra clearance requirements. To
accommodate the weaker tooling, feed torque and speed must be
reduced which results in a comprised quality of tooling.
[0028] Thus, an advantage of using the tool as described herein is
that alternate tooling is shorter and the quality of the hole is
increased. Quality attributes include cutter pocket surface finish
as well as preciseness and/or accuracy of pocket placement. The
shorter tooling of the mill bit 32 compared to the prior art bit 4
herein described provides a stronger cutting device and minimizes
clearance issues with the bit center. Moreover, cutting elements
having an oval cross section are less susceptible to damage than a
cylindrically shaped cutting element. Oval shaped cutting elements
have a cross sectional area exceeding cylindrical elements and
therefore have increased strength. Thus smaller ovals could be used
in a cutting bit thereby increasing cutter number on the same blade
profile.
[0029] FIG. 7 illustrates a side partial sectional view of the drag
bit 25 used with a drilling system 38 for forming a wellbore 39.
Here the drag bit 25 is attached via a threaded connection to a
drill string 40 on the lower end of a drill string 40. The drill
string 40 is connected on its upper end to a top drive 42. The top
drive 42 provides rotational torque to the drill string 40 and drag
bit 25 for drilling through a formation forming the wellbore
39.
[0030] The present invention described herein, therefore, is well
adapted to carry out the objects and attain the ends and advantages
mentioned, as well as others inherent therein. While a presently
preferred embodiment of the invention has been given for purposes
of disclosure, numerous changes exist in the details of procedures
for accomplishing the desired results. For example, the face 22 can
be faceted instead of residing within a single plane, and may be
oblique to the axis A of the cutting element 20. These and other
similar modifications will readily suggest themselves to those
skilled in the art, and are intended to be encompassed within the
spirit of the present invention disclosed herein and the scope of
the appended claims. While the invention has been shown in only one
of its forms, it should be apparent to those skilled in the art
that it is not so limited but is susceptible to various changes
without departing from the scope of the invention.
* * * * *