U.S. patent application number 14/622670 was filed with the patent office on 2015-08-27 for manufacture of low cost bits by infiltration of metal powders.
This patent application is currently assigned to VAREL INTERNATIONAL IND., L.P.. The applicant listed for this patent is Marvin Windsor Amundsen, Federico Bellin, Charles Daniel Johnson, Gary M. Thigpen. Invention is credited to Marvin Windsor Amundsen, Federico Bellin, Charles Daniel Johnson, Gary M. Thigpen.
Application Number | 20150240566 14/622670 |
Document ID | / |
Family ID | 52669401 |
Filed Date | 2015-08-27 |
United States Patent
Application |
20150240566 |
Kind Code |
A1 |
Amundsen; Marvin Windsor ;
et al. |
August 27, 2015 |
MANUFACTURE OF LOW COST BITS BY INFILTRATION OF METAL POWDERS
Abstract
An apparatus and method for manufacturing a downhole tool. The
cemented matrix material is formed from a metal powder, a shoulder
powder, and a binder material, wherein the metal powder and/or the
shoulder powder includes at least one of stainless steel powder,
nickel powder, cobalt powder, iron powder, or powders of other
suitable metals or alloys, or a combination of such mentioned
powders.
Inventors: |
Amundsen; Marvin Windsor;
(Houston, TX) ; Bellin; Federico; (Tomball,
TX) ; Thigpen; Gary M.; (Houston, TX) ;
Johnson; Charles Daniel; (Porter, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Amundsen; Marvin Windsor
Bellin; Federico
Thigpen; Gary M.
Johnson; Charles Daniel |
Houston
Tomball
Houston
Porter |
TX
TX
TX
TX |
US
US
US
US |
|
|
Assignee: |
VAREL INTERNATIONAL IND.,
L.P.
Carrollton
TX
|
Family ID: |
52669401 |
Appl. No.: |
14/622670 |
Filed: |
February 13, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61943141 |
Feb 21, 2014 |
|
|
|
Current U.S.
Class: |
175/425 ;
419/9 |
Current CPC
Class: |
E21B 10/46 20130101;
B22F 7/008 20130101; C22C 1/0433 20130101; B22F 7/08 20130101; C22C
1/1036 20130101; C22C 32/0052 20130101; B22F 3/26 20130101; B22F
1/0003 20130101; C22C 33/0292 20130101; E21B 10/00 20130101 |
International
Class: |
E21B 10/46 20060101
E21B010/46; B22F 1/00 20060101 B22F001/00; B22F 3/26 20060101
B22F003/26; B22F 7/08 20060101 B22F007/08; B22F 7/00 20060101
B22F007/00 |
Claims
1. A downhole tool, comprising: a metal component comprising a top
portion, a bottom portion, and a channel extending from the top
portion to the bottom portion; and an infiltrated metal powder
bonded to an exterior surface and an interior surface of the metal
component, the infiltrated metal powder formed from infiltration of
a binder material with a metal powder, the infiltrated metal powder
coupled to at least the bottom portion of the metal component; an
infiltrated shoulder powder bonded to an exterior surface and an
interior surface of the metal component, the infiltrated shoulder
powder formed from infiltration of the binder material with a
shoulder powder, the infiltrated shoulder powder coupled to at
least the top portion of the metal component, the infiltrated
shoulder powder being positioned above the infiltrated metal
powder, wherein at least one of the metal powder or shoulder powder
used for fabricating the downhole tool comprises: at least one of
stainless steel powder, nickel powder, cobalt powder, iron powder,
or a combination of two or more of these powders; and a
concentration of less than 25% of a tungsten carbide powder or a
tungsten powder, respectively.
2. The downhole tool of claim 1, wherein the metal powder comprises
at least one of stainless steel powder, nickel powder, cobalt
powder, iron powder, or a combination of two or more of these
powders and a concentration of less than 25% of the tungsten
carbide powder.
3. The downhole tool of claim 1, wherein the shoulder powder
comprises at least one of stainless steel powder, nickel powder,
cobalt powder, iron powder, or a combination of two or more of
these powders and a concentration of less than 25% of the tungsten
powder.
4. The downhole tool of claim 1, wherein the metal powder and the
shoulder powder comprise at least one of stainless steel powder,
nickel powder, cobalt powder, iron powder, or a combination of two
or more of these powders and a concentration of less than 25% of
the tungsten carbide powder and the tungsten powder,
respectively.
5. The downhole tool of claim 1, wherein the metal powder is the
same composition as the shoulder powder.
6. The downhole tool of claim 1, wherein the metal powder is a
different composition than the shoulder powder.
7. The downhole tool of claim 6, wherein the metal powder and the
shoulder powder comprise the same powders.
8. The downhole tool of claim 1, wherein the metal powder is formed
of at least more than 25% of at least one of stainless steel
powder, nickel powder, cobalt powder, iron powder, or a combination
of two or more of these powders.
9. The downhole tool of claim 1, wherein the metal powder is formed
of at least more than 30% of at least one of stainless steel
powder, nickel powder, cobalt powder, iron powder, or a combination
of two or more of these powders.
10. The downhole tool of claim 1, wherein the metal powder is
formed of at least more than 40% of at least one of stainless steel
powder, nickel powder, cobalt powder, iron powder, or a combination
of two or more of these powders.
11. The downhole tool of claim 1, wherein the shoulder powder is
formed of at least more than 25% of at least one of stainless steel
powder, nickel powder, cobalt powder, iron powder, or a combination
of two or more of these powders.
12. The downhole tool of claim 1, wherein the shoulder powder is
formed of at least more than 30% of at least one of stainless steel
powder, nickel powder, cobalt powder, iron powder, or a combination
of two or more of these powders.
13. The downhole tool of claim 1, wherein the shoulder powder is
formed of at least more than 40% of at least one of stainless steel
powder, nickel powder, cobalt powder, iron powder, or a combination
of two or more of these powders.
14. The downhole tool of claim 1, wherein at least one of the metal
powder or the shoulder powder comprise a concentration of less than
20% of a tungsten carbide powder or a tungsten powder,
respectively.
15. The downhole tool of claim 1, wherein at least one of the metal
powder or the shoulder powder comprise a concentration of less than
15% of a tungsten carbide powder or a tungsten powder,
respectively.
16. A method for manufacturing a downhole tool, comprising: placing
a blank within a downhole tool casting assembly, the blank
comprising a top portion, a bottom portion, and a channel extending
from the top portion to the bottom portion; placing a mixture
around at least a portion of the surface of the blank within the
downhole tool casting assembly, the mixture comprising a metal
powder and a shoulder powder, the metal powder positioned adjacent
at least the bottom portion of the blank and the shoulder powder
being positioned adjacent to at least the top portion of the blank,
the shoulder powder being positioned above the metal powder;
melting a binder material into the mixture; forming an infiltrated
metal powder and an infiltrated shoulder powder from the mixture
and the binder material; and bonding the infiltrated metal powder
and the infiltrated shoulder powder to the blank, wherein at least
one of the metal powder or shoulder powder used for fabricating the
downhole tool comprises: at least one of stainless steel powder,
nickel powder, cobalt powder, iron powder, or a combination of two
or more of these powders; and a concentration of less than 25% of a
tungsten carbide powder or a tungsten powder, respectively.
17. The method of claim 16, wherein the metal powder comprises at
least one of stainless steel powder, nickel powder, cobalt powder,
iron powder, or a combination of two or more of these powders and a
concentration of less than 25% of the tungsten carbide powder.
18. The method of claim 16, wherein the shoulder powder comprises
at least one of stainless steel powder, nickel powder, cobalt
powder, iron powder, or a combination of two or more of these
powders and a concentration of less than 25% of the tungsten
powder.
19. The method of claim 16, wherein the metal powder and the
shoulder powder comprise at least one of stainless steel powder,
nickel powder, cobalt powder, iron powder, or a combination of two
or more of these powders and a concentration of less than 25% of
the tungsten carbide powder and the tungsten powder,
respectively.
20. The method of claim 16, wherein the metal powder is the same
composition as the shoulder powder.
21. The method of claim 16, wherein the metal powder is a different
composition than the shoulder powder.
22. The method of claim 21, wherein the metal powder and the
shoulder powder comprise the same powders.
23. The method of claim 16, wherein the metal powder is formed of
at least more than 25% of at least one of stainless steel powder,
nickel powder, cobalt powder, iron powder, or a combination of two
or more of these powders.
24. The method of claim 16, wherein the metal powder is formed of
at least more than 30% of at least one of stainless steel powder,
nickel powder, cobalt powder, iron powder, or a combination of two
or more of these powders.
25. The method of claim 16, wherein the metal powder is formed of
at least more than 40% of at least one of stainless steel powder,
nickel powder, cobalt powder, iron powder, or a combination of two
or more of these powders.
26. The method of claim 16, wherein the shoulder powder is formed
of at least more than 25% of at least one of stainless steel
powder, nickel powder, cobalt powder, iron powder, or a combination
of two or more of these powders.
27. The method of claim 16, wherein the shoulder powder is formed
of at least more than 30% of at least one of stainless steel
powder, nickel powder, cobalt powder, iron powder, or a combination
of two or more of these powders.
28. The method of claim 16, wherein the shoulder powder is formed
of at least more than 40% of at least one of stainless steel
powder, nickel powder, cobalt powder, iron powder, or a combination
of two or more of these powders.
29. The method of claim 16, wherein at least one of the metal
powder or the shoulder powder comprise a concentration of less than
20% of a tungsten carbide powder or a tungsten powder,
respectively.
30. The method of claim 16, wherein at least one of the metal
powder or the shoulder powder comprise a concentration of less than
15% of a tungsten carbide powder or a tungsten powder,
respectively.
31. The method of claim 16, further comprising applying a
hardfacing material onto at least a portion of the downhole tool.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This present application claims priority to U.S. Provisional
Patent Application No. 61/943,141, entitled "Manufacture Of Low
Cost Bits By Infiltration Of Metal Powders," filed Feb. 21, 2014,
the disclosure of which is incorporated herein.
BACKGROUND OF THE INVENTION
[0002] This invention relates generally to downhole tools and
methods for manufacturing such items. More particularly, this
invention relates to low cost infiltrated metal powders used in
drilling products including, but not limited to, fixed cutter bits,
polycrystalline diamond compact ("PDC") drill bits, natural diamond
drill bits, thermally stable polycrystalline ("TSP") drill bits,
bi-center bits, core bits, and reamers and stabilizers, and the
methods of manufacturing such items.
[0003] Full hole tungsten carbide matrix drill bits for oilfield
applications have been manufactured and used in drilling since at
least as early as the 1940's. FIG. 1 shows a cross-sectional view
of a downhole tool casting assembly 100 in accordance with the
prior art. The downhole tool casting assembly 100 consists of a
thick-walled mold 110, a stalk 120, one or more nozzle
displacements 122, a blank 124, a funnel 140, and a binder pot 150.
The downhole tool casting assembly 100 is used to fabricate a
casting 200 (FIG. 2) of a downhole tool 200 (FIG. 2), such as a
drill bit 200 (FIG. 2).
[0004] According to a typical downhole tool casting assembly 100,
as shown in FIG. 1, and a method for using the downhole tool
casting assembly 100, the thick-walled mold 110 is fabricated with
a precisely machined interior surface 112, and forms a mold volume
114 located within the interior of the thick-walled mold 110. The
thick-walled mold 110 is made from sand, hard carbon graphite,
ceramic, or other known suitable materials. The precisely machined
interior surface 112 has a shape that is a negative of what will
become the facial features of the eventual bit face. The precisely
machined interior surface 112 is milled and dressed to form the
proper contours of the finished bit 200 (FIG. 2). Various types of
cutters 240 (FIG. 2), known to persons having ordinary skill in the
art, can be placed along the locations of the cutting edges of the
bit 200 (FIG. 2) and can also be optionally placed along the gauge
area 250 (FIG. 2) of the bit 200 (FIG. 2). These cutters 240 (FIG.
2) can be placed during the bit fabrication process or after the
bit 200 (FIG. 2) has been fabricated via brazing or other methods
known to persons having ordinary skill in the art.
[0005] Once the thick-walled mold 110 is fabricated, displacements
are placed at least partially within the mold volume 114 of the
thick-walled mold 110. The displacements are typically fabricated
from clay, sand, graphite, ceramic, or other known suitable
materials. These displacements consist of the center stalk 120 and
the at least one nozzle displacement 122. The center stalk 120 is
positioned substantially within the center of the thick-walled mold
110 and suspended a desired distance from the bottom of the mold's
interior surface 112. The nozzle displacements 122 are positioned
within the thick-walled mold 110 and extend from the center stalk
120 to the bottom of the mold's interior surface 112. The center
stalk 120 and the nozzle displacements 122 are later removed from
the eventual drill bit casting 200 (FIG. 2) so that drilling fluid
(not shown) can flow though the center of the finished bit 200
(FIG. 2) during the drill bit's operation.
[0006] The blank 124 is a cylindrical steel casting mandrel that is
centrally suspended at least partially within the thick-walled mold
110 and around the center stalk 120. The blank 124 is positioned a
predetermined distance down in the thick-walled mold 110. According
to the prior art, the distance between the outer surface of the
blank 124 and the interior surface 112 of the thick-walled mold 110
is typically twelve millimeters ("mm") or more so that potential
cracking of the thick-walled mold 110 is reduced during the casting
process.
[0007] Once the displacements 120, 122 and the blank 124 have been
positioned within the thick-walled mold 110, tungsten carbide
powder 130, which includes some free tungsten, is loaded into the
thick-walled mold 110 so that it fills a portion of the mold volume
114 that is around the lower portion of the blank 124, between the
inner surfaces of the blank 124 and the outer surfaces of the
center stalk 120, and between the nozzle displacements 122.
Shoulder powder 134 is loaded on top of the tungsten carbide powder
130 in an area located at both the area outside of the blank 124
and the area between the blank 124 and the center stalk 120. The
shoulder powder 134 is made of tungsten powder. This shoulder
powder 134 acts to blend the casting to the steel blank 124 and is
machinable. Once the tungsten carbide powder 130 and the shoulder
powder 134 are loaded into the thick-walled mold 110, the
thick-walled mold 110 is typically vibrated to improve the
compaction of the tungsten carbide powder 130 and the shoulder
powder 134. Although the thick-walled mold 110 is vibrated after
the tungsten carbide powder 130 and the shoulder powder 134 are
loaded into the thick-walled mold 110, the vibration of the
thick-walled mold 110 can be done as an intermediate step before,
during, and/or after the shoulder powder 134 is loaded on top of
the tungsten carbide powder 130.
[0008] The funnel 140 is a graphite cylinder that forms a funnel
volume 144 therein. The funnel 140 is coupled to the top portion of
the thick-walled mold 110. A recess 142 is formed at the interior
edge of the funnel 140, which facilitates the funnel 140 coupling
to the upper portion of the thick-walled mold 110. Typically, the
inside diameter of the thick-walled mold 110 is similar to the
inside diameter of the funnel 140 once the funnel 140 and the
thick-walled mold 110 are coupled together.
[0009] The binder pot 150 is a cylinder having a base 156 with an
opening 158 located at the base 156, which extends through the base
156. The binder pot 150 also forms a binder pot volume 154 therein
for holding a binder material 160. The binder pot 150 is coupled to
the top portion of the funnel 140 via a recess 152 that is formed
at the exterior edge of the binder pot 150. This recess 152
facilitates the binder pot 150 coupling to the upper portion of the
funnel 140. Once the downhole tool casting assembly 100 has been
assembled, a predetermined amount of binder material 160 is loaded
into the binder pot volume 154. The typical binder material 160 is
a copper alloy or other suitable known material and may include
some flux powder. Although one example has been provided for
setting up the downhole tool casting assembly 100, other examples
can be used to form the downhole tool casting assembly 100. For
example, the mold 110 and the funnel 140 are formed as a single
component.
[0010] The downhole tool casting assembly 100 is placed within a
furnace (not shown) or other heating structure. The binder material
160 melts and flows into the tungsten carbide powder 130 through
the opening 158 of the binder pot 150. In the furnace, the molten
binder material 160 infiltrates the tungsten carbide powder 130 and
the shoulder powder 134 to fill the interparticle spaces formed
between adjacent particles of tungsten carbide powder 130 and
between adjacent particles of shoulder powder 134. During this
process, a substantial amount of binder material 160 is used so
that it fills at least a substantial portion of the funnel volume
144. This excess binder material 160 in the funnel volume 144
supplies a downward force on the tungsten carbide powder 130 and
the shoulder powder 134. Once the binder material 160 completely
infiltrates the tungsten carbide powder 130 and the shoulder powder
134, the downhole tool casting assembly 100 is pulled from the
furnace and is controllably cooled. Upon cooling, the binder
material 160 solidifies and cements the particles of tungsten
carbide powder 130 and the shoulder powder 134 together into a
coherent integral mass (not shown). The binder material 160 also
bonds this coherent integral mass to the steel blank 124. The
coherent integral mass and the blank 124 collectively form the
matrix body bit 200 (FIG. 2). Once cooled, the thick-walled mold
110 is broken away from the casting 200 (FIG. 2). The casting 200
(FIG. 2) then undergoes finishing steps which are known to persons
having ordinary skill in the art, including the addition of a
threaded connection 220 (FIG. 2) coupled to the top portion of the
blank 124. Although the matrix body bit 200 (FIG. 2), or casting
200 (FIG. 2), has been described to be formed using the process and
equipment described above, the process and/or the equipment can be
varied to form the matrix body bit 200 (FIG. 2).
[0011] FIG. 2 shows a perspective view of a conventional drill bit
200, or conventional fixed cutter drill bit 200, in accordance with
the prior art. Referring to FIG. 2, the conventional drill bit 200
includes a bit body 210 that is coupled to the shank 124 and is
designed to rotate in a counter-clockwise direction 290. The shank
124 is coupled to an API connection 216 which includes a threaded
connection 217 at one end 220. The threaded connection 217 couples
to a drill string (not shown) or some other equipment that is
coupled to the drill string. The threaded connection 217 is shown
to be positioned on the exterior surface of the one end 220. This
positioning assumes that the conventional drill bit 200 is coupled
to a corresponding threaded connection located on the interior
surface of a drill string (not shown). However, the threaded
connection 217 at the one end 220 is alternatively positioned on
the interior surface of the one end 220 if the corresponding
threaded connection of the drill string, or other equipment, is
positioned on its exterior surface in other exemplary embodiments.
A bore (not shown) is formed longitudinally through the shank 124
and extends into the bit body 210 forming a plenum (not shown),
which communicates drilling fluid during drilling operations from
within the bit body 210 to a drill bit face 211 via one or more
conventional nozzle sockets 214 formed within the bit body 210.
These conventional nozzle sockets 214 are cylindrically shaped
within the conventional drill bit 200.
[0012] The bit body 210 includes a plurality of gauge sections 250
and a plurality of blades 230 extending from the drill bit face 211
of the bit body 210 towards the threaded connection 217, where each
blade 230 extends to and terminates at a respective gauge section
250. The blade 230 and the respective gauge section 250 are formed
as a single component, but are formed separately in certain other
conventional drill bits 200. The drill bit face 211 is positioned
at one end of the bit body 210 furthest away from the shank 124.
The plurality of blades 230 form the cutting surface of the
conventional drill bit 200. One or more of these plurality of
blades 230 are either coupled to the bit body 210 or are integrally
formed with the bit body 210. The gauge sections 250 are positioned
at an end of the bit body 210 adjacent the shank 124. The gauge
section 250 includes one or more gauge cutters (not shown) in
certain conventional drill bits 200. The gauge sections 250
typically define and hold the full hole diameter of the drilled
hole. The blades 230 and/or the gauge sections 250 are oriented in
a spiral configuration according to some of the prior art. However,
in other conventional drill bits, the blades 230 and/or the gauge
sections 250 are oriented in a non-spiral configuration. A junk
slot 222 is formed, or milled, between each consecutive blade 230,
which allows for cuttings and drilling fluid to return to the
surface of the wellbore (not shown) once the drilling fluid is
discharged from the nozzle sockets 214 during drilling
operations.
[0013] A plurality of cutters 240 are coupled to each of the blades
230 within a respective cutter pocket 260 formed therein. The
cutters 240 are generally formed in an elongated cylindrical shape;
however, these cutters 240 can be formed in other shapes, such as
disc-shaped or conical-shaped. The cutters 240 typically include a
substrate 242, oftentimes cylindrically shaped, and a cutting
surface 244, also cylindrically shaped, disposed at one end of the
substrate 242 and oriented to extend outwardly from the blade 230
when coupled within the respective cutter pocket 260. The cutting
surface 244 can be formed from a hard material, such as bound
particles of polycrystalline diamond forming a diamond table, and
be disposed on or coupled to a substantially circular profiled end
surface of the substrate 242 of each cutter 240. Typically, the
polycrystalline diamond cutters ("PDC") are fabricated separately
from the bit body 210 and are secured within a respective cutter
pocket 260 formed within the bit body 210. Although one type of
cutter 240 used within the conventional drill bit 200 is a PDC
cutter; other types of cutters also are contemplated as being used
within the conventional drill bit 200. These cutters 240 and
portions of the bit body 210 deform the earth formation by scraping
and/or shearing depending upon the type of conventional drill bit
200.
[0014] The tungsten carbide matrix used in forming the drill bit
200 is very brittle, not hard, and not ductile; thereby causing
eventual failure of the bit 200 during drilling operations.
Further, the cost of tungsten carbide 130 (FIG. 1) and tungsten 134
(FIG. 1) powders used in forming the drill bit 200 are relatively
expensive. There is a need to fabricate downhole tools using
cheaper materials, either alone or in combination with the tungsten
carbide 130 (FIG. 1) and/or tungsten 134 (FIG. 1) powders thereby
using less tungsten carbide 130 (FIG. 1) and/or tungsten 134 (FIG.
1) powders and making the bit 200 lower costing. Further, there is
a need to use other materials in fabricating these downhole tools
to modify the properties of the coherent integral mass, or bit body
210, allowing the downhole tool 200 perform better and last longer
in the hole.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The foregoing and other features and aspects of the
invention will be best understood with reference to the following
description of certain exemplary embodiments of the invention, when
read in conjunction with the accompanying drawings, wherein:
[0016] FIG. 1 shows a cross-sectional view of a downhole tool
casting assembly in accordance with the prior art;
[0017] FIG. 2 shows a perspective view of a conventional fixed
cutter drill bit in accordance with the prior art;
[0018] FIG. 3 shows a cross-sectional view of a downhole tool
casting assembly in accordance with an exemplary embodiment of the
invention; and
[0019] FIG. 4 shows a partial cross-sectional view of a downhole
tool casting formed using the downhole tool casting assembly of
FIG. 3 in accordance with the exemplary embodiment.
DETAILED DESCRIPTION OF THE INVENTION
[0020] This invention relates generally to downhole tools and
methods for manufacturing such items. More particularly, this
invention relates to low cost infiltrated metal powders used in
drilling products including, but not limited to, fixed cutter bits,
polycrystalline diamond compact ("PDC") drill bits, natural diamond
drill bits, thermally stable polycrystalline ("TSP") drill bits,
bi-center bits, core bits, and reamers and stabilizers, and the
methods of manufacturing such items. Although the description
provided below is related to a drill bit, embodiments of the
present invention relate to any infiltrated metal powders used to
fabricate a drilling product.
[0021] FIG. 3 shows a cross-sectional view of a downhole tool
casting assembly 300 in accordance with the exemplary embodiment.
Referring to FIG. 3, the downhole tool casting assembly 300
includes a mold 310, a stalk 320, one or more nozzle displacements
322, a blank 324, a funnel 340, and a binder pot 350. The downhole
tool casting assembly 300 is used to fabricate a casting 400 (FIG.
4) of a downhole tool, such as a fixed cutter bit, a PDC drill bit,
a natural diamond drill bit, and a TSP drill bit. However, the
downhole tool casting assembly 300 is modified in other exemplary
embodiments to fabricate other downhole tools, such as a bi-center
bit, a core bit, and a matrix bodied reamer and stabilizer.
[0022] The mold 310 is fabricated with a precisely machined
interior surface 312, and forms a mold volume 314 located within
the interior of the mold 310. The mold 310 is made from sand, hard
carbon graphite, ceramic, or other known suitable materials. The
precisely machined interior surface 312 has a shape that is a
negative of what will become the facial features of the eventual
bit face. The precisely machined interior surface 312 is milled and
dressed to form the proper contours of the finished bit. Various
types of cutters, such as the cutters 240 (FIG. 2), known to
persons having ordinary skill in the art, are placed along the
locations of the cutting edges of the bit and are optionally placed
along the gage area of the bit. These cutters are placed during the
bit fabrication process or after the bit has been fabricated via
brazing or other methods known to persons having ordinary skill in
the art.
[0023] Once the mold 310 is fabricated, displacements are placed at
least partially within the mold volume 314. The displacements are
fabricated from clay, sand, graphite, ceramic, or other known
suitable materials. These displacements include the center stalk
320 and the at least one nozzle displacement 322. The center stalk
320 is positioned substantially within the center of the mold 310
and suspended a desired distance from the bottom of the mold's
interior surface 312. The nozzle displacements 322 are positioned
within the mold 310 and extend from the center stalk 320 to the
bottom of the mold's interior surface 312. The center stalk 320 and
the nozzle displacements 322 are later removed from the eventual
drill bit casting so that drilling fluid (not shown) flows though
the center of the finished bit during the drill bit's
operation.
[0024] The blank 324, which has been previously described above
with respect to blank 124, is centrally suspended at least
partially within the mold 310 and around the center stalk 320. The
blank 324 is positioned a predetermined distance down in the mold
310. The distance between the outer surface of the blank 324 and
the interior surface 312 of the mold 310 is about twelve
millimeters or more so that potential cracking of the mold 310 is
reduced during the casting process. However, this distance is
varied in other exemplary embodiments depending upon the strength
of the mold 310 or the method and/or equipment used in fabricating
the casting. According to some exemplary embodiments, a coating
(not shown) may optionally be applied to at least a portion of the
surface of the blank 324. This coating may be applied to improve
the bonding between the powders 330, 334, which are described in
more detail below, and the blank 324.
[0025] Once the displacements 320, 322 and the blank 324 have been
positioned within the mold 310, metal powder 330 is loaded into the
mold 110 so that it fills a portion of the mold volume 314 that is
around at least a lower portion of the blank 324, between the inner
surfaces of the blank 324 and the outer surfaces of the center
stalk 320, and between the nozzle displacements 322. Shoulder
powder 334 is loaded on top of the metal powder 330 in an area
located at both the area outside of the blank 324 and the area
between the blank 324 and the center stalk 320. According to some
exemplary embodiments, the metal powder 330 and the shoulder powder
334 are the same powders with the same or similar compositions.
However, in other exemplary embodiments, the metal powder 330 and
the shoulder powder 334 are different powders, having some or none
of the powder materials being the same. Also, the metal powder 330
and the shoulder powder 334 may have the same material but at a
different composition, according to some exemplary embodiments.
[0026] According to some exemplary embodiments, the metal powder
330 includes at least one of stainless steel powder, nickel powder,
cobalt powder, iron powder, or powders of other suitable metals or
alloys, or a combination of such mentioned powders. According to
some exemplary embodiments, the metal powder 330 is formed of at
least more than 25% of at least one of these powders mentioned
immediately above. For example, the metal powder 330 is formed of
at least more than 25% of at least one of stainless steel powder,
nickel powder, cobalt powder, iron powder, or a combination of such
mentioned powders. According to some other exemplary embodiments,
the metal powder 330 is formed of at least more than 30% of at
least one of these powders mentioned immediately above. In yet
other exemplary embodiments, the metal powder 330 is formed of at
least more than 40% of at least one of these powders mentioned
immediately above. In an alternative exemplary embodiment, the
metal powder 330 is formed with less than 25% of tungsten carbide
powders. In yet another alternative exemplary embodiment, the metal
powder 330 is formed with less than 20% of tungsten carbide
powders. In yet another exemplary embodiment, the metal powder 330
is formed with less than 15% of tungsten carbide powders.
[0027] According to some exemplary embodiments, the shoulder powder
334 includes at least one of stainless steel powder, nickel powder,
cobalt powder, iron powder, or powders of other suitable metals or
alloys, or a combination of such mentioned powders. According to
some exemplary embodiments, the shoulder powder 334 is formed of at
least more than 25% of at least one of these powders mentioned
immediately above. For example, the shoulder powder 334 is formed
of at least more than 25% of at least one of stainless steel
powder, nickel powder, cobalt powder, iron powder, or a combination
of such mentioned powders. According to some other exemplary
embodiments, the shoulder powder 334 is formed of at least more
than 30% of at least one of these powders mentioned immediately
above. In yet other exemplary embodiments, the shoulder powder 334
is formed of at least more than 40% of at least one of these
powders mentioned immediately above. In an alternative exemplary
embodiment, the shoulder powder 334 is formed with less than 25% of
tungsten powders. In yet another alternative exemplary embodiment,
the shoulder powder 334 is formed with less than 20% of tungsten
powders. In yet another exemplary embodiment, the shoulder powder
334 is formed with less than 15% of tungsten powders.
[0028] Once the metal powder 330 and the shoulder powder 334 are
loaded into the mold 310, the mold 310 is vibrated, in some
exemplary embodiments, to improve the compaction of the tungsten
carbide powder 330 and the shoulder powder 334. Although the mold
310 is vibrated after the metal powder 330 and the shoulder powder
334 are loaded into the mold 310, the vibration of the mold 310 is
done as an intermediate step before, during, and/or after the
shoulder powder 334 is loaded on top of the metal powder 330.
[0029] The funnel 340 is a graphite cylinder that forms a funnel
volume 344 therein. The funnel 340 is coupled to the top portion of
the mold 310. A recess 342 is formed at the interior edge of the
funnel 340, which facilitates the funnel 340 coupling to the upper
portion of the mold 310. In some exemplary embodiments, the inside
diameter of the mold 310 is similar to the inside diameter of the
funnel 340 once the funnel 340 and the mold 310 are coupled
together.
[0030] The binder pot 350 is a cylinder having a base 356 with an
opening 358 located at the base 356, which extends through the base
356. The binder pot 350 also forms a binder pot volume 354 therein
for holding a binder material 360. The binder pot 350 is coupled to
the top portion of the funnel 340 via a recess 352 that is formed
at the exterior edge of the binder pot 350. This recess 352
facilitates the binder pot 350 coupling to the upper portion of the
funnel 340. Once the downhole tool casting assembly 300 has been
assembled, a predetermined amount of binder material 360 is loaded
into the binder pot volume 354. The typical binder material 360 is
a copper alloy or other suitable known material. According to some
exemplary embodiments, the binder material 360, or braze material,
includes MF53 and a small amount of B-1 dry Handyflo flux powder,
which are known to people having ordinary skill in the art.
Although one example has been provided for setting up the downhole
tool casting assembly 300, other examples having greater, fewer, or
different components are used to form the downhole tool casting
assembly 300. For instance, the mold 310 and the funnel 340 are
combined into a single component in some exemplary embodiments.
[0031] The downhole tool casting assembly 300 is placed within a
furnace (not shown) or other heating structure to undergo a brazing
process. During the brazing process, the binder material 360 melts
and flows into the shoulder powder 334 and the metal powder 330
through the opening 358 of the binder pot 350. In the furnace, the
molten binder material 360 infiltrates the metal powder 330 and the
shoulder powder 334 to fill the interparticle spaces formed between
adjacent particles of metal powder 330 and/or shoulder powder 334.
During this process, a substantial amount of binder material 360 is
used so that it fills at least a substantial portion of the funnel
volume 344. This excess binder material 360 in the funnel volume
344 supplies a downward force on the metal powder 330 and the
shoulder powder 334. According to some exemplary embodiments, the
brazing process is performed in air atmosphere at a brazing
temperature in excess of 2100.degree. F. and for a time
commensurate with the downhole tool 400 (FIG. 4), or bit, size. For
example, for a 8'' bit size, the downhole tool casting assembly 300
is placed at a temperature in of 2100.degree. F. for about one
hour.
[0032] Once the binder material 360 completely infiltrates the
metal powder 330 and the shoulder powder 334, the downhole tool
casting assembly 300 is pulled from the furnace and is controllably
cooled. Upon cooling, the binder material 360 solidifies and
cements the particles of metal powder 330 and shoulder powder 334
together into a coherent integral mass 410 (FIG. 4). The binder
material 360 also bonds this coherent integral mass 410 (FIG. 4) to
the blank 324, according to certain exemplary embodiments. The
coherent integral mass 410 (FIG. 4) and the blank 324 collectively
form the infiltrated bit 400 (FIG. 4), a portion of which is shown
in FIG. 4. Once cooled, the mold 310 is broken away from the
casting. The casting then undergoes finishing steps which are known
to persons of ordinary skill in the art, including cleaning of the
casting and the coupling of a threaded connection (not shown) or
AISI 4140 upper section, similar to API connection 216 (FIG. 2), to
the top portion of the blank 324. According to certain exemplary
embodiments, the AISI 4140 upper section is welded to the blank 324
by submerged arc welding ("SAW") or gas metal arc welding ("GMAW")
according to the usual method of manufacture. Further, according to
some exemplary embodiments, a protective layer of plasma
transferred ARC ("PTA") is applied onto at least a portion of the
downhole tool, such as the surface of the blades, so that the
downhole tool can better handle abrasion. Although the infiltrated
bit 400 (FIG. 4) has been described to be formed using the process
and equipment described above, the process and/or the equipment can
be varied to still form the infiltrated bit 400 (FIG. 4).
[0033] FIG. 4 shows a partial cross-sectional view of a downhole
tool casting 400 formed using the downhole tool casting assembly
300 of FIG. 3 in accordance with the exemplary embodiment.
Referring to FIG. 4, the downhole tool casting 400 includes the
coherent integral mass 410, the blank 324, and the passageways 420
formed from the removal of the displacements 320, 322 (FIG. 3). As
mentioned above with respect to FIG. 3, the coherent integral mass
410 is formed using the metal powder 330 (FIG. 3), as described
above, and the shoulder powder 334 (FIG. 3), also as described
above. The metal powder 330 (FIG. 3) and the shoulder powder 334
(FIG. 3) are infiltrated with binder material 360 (FIG. 3) to form
infiltrated metal powder 430 and infiltrated shoulder powder 434,
respectively. According to the exemplary embodiment illustrated in
FIGS. 3 and 4, the infiltrated shoulder powder 434 may be of the
same or different composition and/or of the same or different
powder materials than the infiltrated metal powder 430.
[0034] According to exemplary embodiments, the metal powders and/or
the shoulder powders used to manufacture the downhole tool provide
improved characteristics than those used in the prior art. As
previously mentioned, the tungsten carbide powder has been used in
lieu of the above described metal powders and tungsten powder has
been used in lieu of the shoulder powder mentioned above. When
testing an infiltrated nickel sample using a Charpy test, the force
needed to break the sample was found to be 9 ft-lbs, while the
force needed to break tungsten carbide matrix sample was 1 ft-lbs
at the same conditions. Thus, the infiltrated nickel sample was
found to be about 9 times stronger. Similarly, an infiltrated
stainless steel sample was found to need 50 ft-lbs to break the
sample at the same conditions, thereby making it about 50 times
stronger than the tungsten carbide matrix sample. Further, the
infiltrated nickel sample was found to have a hardness of HBW 84,
whereas the tungsten carbide matrix sample is very brittle that
hardness tests are generally not performed on it. The infiltrated
stainless steel sample was found to have a hardness of HBW 103.
With respect to ductile tests, the infiltrated nickel sample was
found to be more ductile than the tungsten carbide matrix sample,
and the infiltrated stainless steel sample was found to be more
ductile than the infiltrated nickel sample. The infiltrated nickel
sample was found to have a yield lbs. of 1,160, an ultimate load
lbs. of 2,730, a yield P.S.I. of 24,200 and a tensile P.S.I. of
57,000, while the infiltrated stainless steel sample was found to
have a yield lbs. of 2,330, an ultimate load lbs. of 4,470, a yield
P.S.I. of 47,900, and a tensile P.S.I. of 91,700. Both nickel
powder and stainless steel powder are cheaper than those powders
presently used.
[0035] Although the invention has been described with reference to
specific embodiments, these descriptions are not meant to be
construed in a limiting sense. Various modifications of the
disclosed embodiments, as well as alternative embodiments of the
invention will become apparent to persons skilled in the art upon
reference to the description of the invention. It should be
appreciated by those skilled in the art that the conception and the
specific embodiments disclosed may be readily utilized as a basis
for modifying or designing other structures for carrying out the
same purposes of the invention. It should also be realized by those
skilled in the art that such equivalent constructions do not depart
from the spirit and scope of the invention as set forth in the
appended claims. It is therefore, contemplated that the claims will
cover any such modifications or embodiments that fall within the
scope of the invention.
* * * * *