U.S. patent application number 12/541399 was filed with the patent office on 2010-02-18 for bit cone with hardfaced nose.
This patent application is currently assigned to Baker Hughes Incorporated. Invention is credited to Floyd C. Felderhoff, Mark A. Freeman, Kenneth E. Gilmore, Alan J. Massey, Glen A. Stanfield.
Application Number | 20100038146 12/541399 |
Document ID | / |
Family ID | 41669700 |
Filed Date | 2010-02-18 |
United States Patent
Application |
20100038146 |
Kind Code |
A1 |
Felderhoff; Floyd C. ; et
al. |
February 18, 2010 |
Bit Cone With Hardfaced Nose
Abstract
A drill bit for drilling a wellbore, the drill bit having a
cutter which has tungsten carbide inserts and a spear point. The
spear point has a neck that joins a smooth portion of the cutter
and blades that extend from the neck and converge to an apex. The
blades define valleys or spaces between them. A layer of hardfacing
is applied to the entire spear point including the interim spaces
and the neck.
Inventors: |
Felderhoff; Floyd C.;
(Montgomery, TX) ; Freeman; Mark A.; (Bloomfield,
CO) ; Massey; Alan J.; (Houston, TX) ;
Gilmore; Kenneth E.; (Cleveland, TX) ; Stanfield;
Glen A.; (Tomball, TX) |
Correspondence
Address: |
Bracewell & Giuliani LLP
P.O. Box 61389
Houston
TX
77208-1389
US
|
Assignee: |
Baker Hughes Incorporated
Houston
TX
|
Family ID: |
41669700 |
Appl. No.: |
12/541399 |
Filed: |
August 14, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61088991 |
Aug 14, 2008 |
|
|
|
Current U.S.
Class: |
175/374 |
Current CPC
Class: |
E21B 10/50 20130101;
E21B 10/16 20130101 |
Class at
Publication: |
175/374 |
International
Class: |
E21B 10/08 20060101
E21B010/08 |
Claims
1. An earth boring bit, comprising in combination: a body with a
longitudinal bit axis; three bit legs depending from the body;
first, second, and third cutters, each rotatably mounted to one of
the bit legs; at least one of the cutters having a metal shell with
a nose section extending inward toward the bit axis from the metal
shell, the nose section having compacts located thereon and
protruding therefrom for disintegrating an earth formation, the
nose section being free of hardfacing; and at least one other of
the cutters having a metal shell with a nose section extending
toward the bit axis, the nose section of the at least one other of
the cutters having hardfacing located thereon.
2. The earth boring bit of claim 1, wherein the nose section having
hardfacing located thereon further comprises: a spear point having
a neck which joins the metal shell of the at least one other of the
cutters, the spear point having a plurality of blades extending
from the neck, the blades converging to an apex and being
circumferentially separated from each other about a cutter axis of
the at least one other of the cutters, defining a space between
each of the blades; and a layer of hardfacing formed on the neck,
the blades and the spaces between each of the blades, the
hardfacing being tungsten carbide particles in a matrix for
protecting the neck and spaces from erosion.
3. The earth boring bit of claim 1, wherein the nose section having
hardfacing located thereon extends a desired distance toward the
bit axis and is positioned closest to the bit axis than any of the
other cutters:
4. An earth boring bit, comprising in combination: a body with a
bit axis; three bit legs depending from the body; first, second,
and third cutters, each rotatably mounted to one of the bit legs;
the first cutter having a metal shell with at least one row of
compacts located thereon and protruding from the metal shell for
disintegrating an earth formation, the metal shell having a smooth
conical surface extending inward from the at least one row of
compacts, the smooth conical surface being free of hardfacing; a
spear point having a neck which joins the smooth conical surface of
the first cutter, the spear point having a plurality of blades
extending from the neck, the blades converging to an apex and being
circumferentially separated from each other about a cutter axis of
the first cutter, defining a space between each of the blades; and
a layer of hardfacing formed on the neck, the blades and the spaces
between each of the blades, the hardfacing being tungsten carbide
particles in a matrix for protecting the neck and spaces from
erosion.
5. The earth boring bit of claim 4, wherein the spear point extends
axially along the cutter axis of the first cutter a select distance
such that the apex of the spear is closer to the bit axis than any
portion of the second and third cutters.
6. The earth boring bit of claim 4, wherein said at least one row
of compacts comprises: an outer row of compacts located thereon, an
intermediate row of compacts located thereon at a lesser distance
from the bit axis than the outer row, and an inner row of compacts
located thereon at a lesser distance from the bit axis than the
intermediate row.
7. The earth boring bit of claim 6, wherein the first cutter is
free of hardfacing from the outer row of compacts to the neck of
the spear point.
8. The earth boring bit of claim 7, wherein each of the second and
third cutters further comprises: a metal shell with a nose section
containing at least one compact that protrudes therefrom for
disintegrating the earth formation.
9. The earth boring bit of claim 4, further comprising: the second
cutter having a metal shell with a nose section extending axially
toward the longitudinal axis from the metal shell along the axis of
the second cutter, the nose section of the second cutter having
compacts protruding thereform, the nose section of the second
cutter being free of hardfacing.
10. The earth boring bit of claim 9, further comprising: the second
cutter having an outer row of compacts protruding therefrom, an
intermediate row of compacts protruding thereform and being at a
lesser distance from the bit axis than the outer row of compacts of
the second cutter and a farther distance from the bit axis than the
compacts located on the nose section of the second cutter.
11. The earth boring bit of claim 4, further comprising: the third
cutter having a metal shell with a nose section extending axially
toward the longitudinal axis from the metal shell along the axis of
the second cutter, the nose section of the third cutter having
compacts protruding therefrom, the nose section of the third cutter
being free of hardfacing.
12. The earth boring bit of claim 11, further comprising: the third
cutter having an outer row of compacts protruding therefrom, an
intermediate row of compacts protruding therefrom and at a lesser
distance from the bit axis than the outer row of compacts of the
third cutter.
13. An earth boring bit comprising in combination: a body with a
bit axis; three bit legs depending from the body; first, second,
and third cutters, each rotatably mounted to one of the bit legs;
the first cutter having a metal shell with an outer row, an
intermediate row, and an inner row of compacts located thereon and
protruding therefrom, the intermediate row being at a lesser
distance from the bit axis than the outer row, and the inner row
being at a lesser distance from the bit axis than the intermediate
row, the metal shell having a smooth conical surface extending
inward from the inner row of compacts, the smooth conical surface
being free of hardfacing; a spear point having a neck which joins
the smooth conical surface of the first cutter, the spear point
having a plurality of blades extending from the neck, the blades
converging to an apex and being circumferentially separated from
each other about a first cutter axis of the first cutter, defining
a space between each of the blades; a layer of hardfacing formed on
the neck, the blades and the spaces between each of the blades, the
hardfacing being tungsten carbide particles in a matrix for
protecting the neck and spaces from erosion; and the second and
third cutters each having a metal shell with at least one row of
compacts located thereon and protruding therefrom.
14. The earth boring bit of claim 13, wherein the metal shell of
the first cutter is free of hardfacing between the outer row and
the neck of the spear point.
15. The earth boring bit of claim 13, wherein the second cutter
further comprises: a metal shell with a nose section extending
inward toward the bit axis, the nose section of the second cutter
having compacts located thereon and protruding therefrom; an outer
row of compacts located on the metal shell of the second cutter and
protruding therefrom outward from the compacts on the nose section
of the second cutter; and an intermediate row of compacts located
on the metal shell of the second cutter and protruding therefrom
between the compacts on the nose section and the outer row of
compacts on the metal shell of the second cutter.
16. The earth boring bit of claim 15, wherein the third cutter
further comprises: a metal shell with a nose section extending
inward toward the bit axis, the nose section of the third cutter
having a row of compacts located thereon and protruding therefrom;
an outer row of compacts located on the metal shell of the third
cutter and protruding therefrom; and an intermediate row of
compacts located on the metal shell of the third cutter between the
compacts on the nose section and the outer row of compacts on the
metal shell of the third cutter.
17. The earth boring bit of claim 16, wherein: a distance between
the outer row of compacts and the intermediate row of compacts on
the first cutter, measured along the first cutter axis, is less
than a distance between the outer row of compacts and the
intermediate row of compacts on the second cutter, measured along a
second cutter axis.
18. The earth boring bit of claim 17, wherein: the distance between
the outer row of compacts and the intermediate row of compacts on
the second cutter is less than a distance between the outer row of
compacts and the intermediate row of compacts on the third cutter,
measured along a third cutter axis.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to provisional application
61/088,991, filled Aug. 14, 2008.
FIELD OF THE INVENTION
[0002] This invention relates to improvements to earth-boring bits
having rotating cones with cutting structures and in particular to
hardfacing a spear point to enhance wear resistance.
BACKGROUND OF THE INVENTION
[0003] In drilling bore holes in earthen formations by the rotary
method, rock bits fitted with one, two or three rolling cutters are
employed. The bit is s secured to the lower end of a drill string
that is rotated from the surface, or the bit is rotated by downhole
motor or turbines. The cutters mounted on the bit roll and slide
upon the bottom of the bore hole as the bit is rotated, thereby
engaging and disengaging the formation material to be removed. The
roller cutters are provides with cutting elements that are forced
to penetrate and gouge the bottom of the borehole by weights of the
drill string. The cuttings from the bottom and sidewalls of the
borehole are washed away by drilling fluid that is pumped down from
the surface through the hollow drill string.
[0004] One type of cutting element in widespread use is a tungsten
carbide insert which is interference pressed into an aperture in
the cutter body. Tungsten carbide is metal which is harder than the
steel body of the cutter and has a cylindrical portion and a
cutting tip portion. The cutting tip portion is formed in various
configurations, such as chisel, hemispherical or conical, depending
upon the type of formation to be drilled. Some of the inserts have
very aggressive cutting structure designs and carbide grades that
allow the bits to drill in both soft and medium formations with the
same bit.
[0005] Another type of rolling cutter earth-boring bit is commonly
known as a "steel-tooth" or "milled-tooth" bit. Typically these
bits are for penetration into relatively soft geological formations
of the earth. The strength and fracture-toughness of the steel
teeth permits the use of relatively long teeth, which enables the
aggressive gouging and scraping actions that are advantageous for
rapid penetration of soft formations with low compressive
strengths.
[0006] However, it is rare that geological formations consist
entirely of soft material with low compressive strength. Often,
there are streaks of hard, abrasive materials that a steel-tooth
bit should penetrate economically without damage to the bit.
Although steel teeth possess good strength, abrasion resistance is
inadequate to permit continued rapid penetration of hard or
abrasive streaks. Consequently, it has been common in the arts
since at least the 1930s to provide a layer of wear-resistance
metallurgical material called "hardfacing" over those portions of
the teeth to the severest wear. The hardfacing typically consists
of extremely hard particles, such as sintered, cast, or
macro-crystalline tungsten carbide, dispersed in a steel matrix.
Such hardfacing materials are applied by welding a metallic matrix
to the surface to be hardfaced and applying the hard particles to
the matrix to form a uniform dispersion of hard particles in the
matrix.
[0007] Unlike a tungsten carbide insert bit teeth of a steel-tooth
bit are not susceptible to stress cracking due to excessive heat. A
steel-tooth bit would be able to drill the relatively soft
non-abrasive formations mentioned above with case stress cracking
on heel rows of insert bits. However, because of the hardness and
thickness of adjacent formations, a steel-tooth bit would wear too
quickly, thus is not a preferred choice in those areas.
[0008] FIG. 1 shows a prior art earth-boring bit 11, having a body
13 with three bit legs 15 depending therefrom. A cone 17 is
rotatably mounted to each of the bit legs 15. Each cone 17 is
formed of a steel shell or body. Each cone 17 has a plurality of
inner row compacts or carbide inserts 19, arranged in at least one
inner row. A plurality of outer or heel row compacts 21 are
adjacent to a gage surface 23 of each cone 17. It is common for
cones 17 to have different numbers of rows. In the embodiment
shown, heel row compacts 21 are generally ovoid, although different
shapes could be used.
SUMMARY OF THE INVENTION
[0009] In this invention, the bit has a cutter which has tungsten
carbide inserts and a spear point. The spear point has a neck that
joins a smooth portion of the cutter and blades that extend from
the neck and converge to an apex. The blades define valleys or
spaces between them.
[0010] A layer of hardfacing is applied to the entire spear point
including the interim spaces and the neck. This hardfacing may be
of a conventional type comprising tungsten carbide particles in a
steel alloy matrix.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a side elevation of a prior art earth-boring
bit.
[0012] FIG. 2 is a bottom view of an earth-boring bit having a cone
hardfaced in accordance with this invention.
DETAILED DESCRIPTION OF THE INVENTION
[0013] Referring to FIG. 2, bit 27 of this invention has a body,
bit legs, and a threaded section that are not shown but may be the
same as in prior art bit 11 of FIG. 1. Bit 27 has a first cone 29,
a second cone 31, and a third cone 33. Each cone 29, 31, 33 has a
plurality of compacts 35 located on outer and inner rows. Inserts
37 are also located along the inner and outer rows of each cone 29,
31, 33. Compacts 35 are formed of cemented carbide, typically
tungsten carbide that is usually homogenous and formed in a die and
consolidated by sintering techniques. Optionally, at least one
layer of diamond may be formed on the cutting tip. Also, as another
option, portions of the carbide material placed in the die and
sintered may be of different grades.
[0014] First cone 29 has an outer row 39 and an intermediate row 41
of compacts 35, which are located adjacent the gage surface of
first cone 29. An inner row 43 is located a short distance inward
from intermediate row 41 toward the bit axis. A thin annular
conical band 45 is located between intermediate row 41 and inner
row 43. First cone 29 has a spear point 47 that is conventional and
comprises radially extending blades. A layer of hardfacing 49 is
applied over spear 47 and a segment of a nose section 50 of cone
29. A conical surface 51 extends from inner row 43 to the neck
portion of spear point 47. A layer of hardfacing 49 may be applied
to a portion of conical surface 51 near the neck portion of spear
47. The hardfacing 49 of spear 47 reduces the amount of wear in the
nose area 50. Hardfacing 49, combined with the use of compacts 35
on inner row 43, intermediate row 41, and outer rows 39 reduces the
total amount of wear of cone 29.
[0015] Second cone 31 has an outer row 53 and an intermediate row
55 of compacts 35. The nose portion 56 of cone 31 extends axially
from intermediate row 55, forming conical band 57. In this
embodiment, an inner row 59 of compacts 35 are located on the nose
portion 56 of cone 31. Alternatively, milled steel teeth could be
formed on the nose portion 56 of cone 31, in place of compacts 35
on inner row 59. If an inner row of steel teeth were formed on the
nose portion 56 of cone 31, hardfacing could be applied over the
teeth and sections of the nose portion 56 of cone 31 and conical
band 57.
[0016] Third cone 33 has an outer row 61 and an intermediate row 63
of compacts 35. The nose portion of cone 33 extends axially from
intermediate row 63, forming conical band 65. In this embodiment an
inner row 67 of compacts 35 are located on the nose portion of cone
33. An additional set of small compacts 68 are located on the end
69 of the nose portion of cone 33. Alternatively, milled steel
teeth could be formed on the nose portion of cone 33, in place of
compacts 35 on inner row 67 and compacts 68 on nose end 69. If an
inner row of steel teeth were placed on the nose portion of cone
33, hardfacing could be applied over the teeth, and sections of the
nose portion of cone 33 and conical band 65.
[0017] In operation, bit 27 is run conventionally. The combination
of compacts 35, inserts 37, and hardfacing 49 applied to the nose
section 50 of cone 29 reduces wear and erosion, increasing the life
of the bit 27. 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.
* * * * *