Note: Descriptions are shown in the official language in which they were submitted.
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METHOD OF FABRICATING TOOLS FOR EARTH BORING
TECHNICAL FIELD OF THE INVENTION
This invention relates to a method of fabricating
tools for earth boring arid more particularly to
stereolithographic fabrication of molds for the
manufacture of tools for earth boring.
BACKGROUND OF THE INVENTION
Heretofore, earth boring tools were fabricated by a
process that started with a design of parts for the tool
and then painstakingly produce a prototype of each part
and assemble the parts into the desired tool. All this
involved considerable time, effort and expense and
oftentimes the process had to be repeated before an
acceptable earth boring tool was ready for production.
A present basic process for manufacturing tools for
earth boring, for example a drill bit, is to machine a
solid billet of steel into the desired final form of the
bit body after the design of the bit has been approved.
An improvement in this basic process is to cast the body
of the bit into a form approximating the final body form.
This permitted a substantial reduction in machining from
the basic process and improved the production of tools
for earth boring considering both the time factor and the
cost factor. The casting process for the fabrication of
tools is complicated by the addition of the metal casting
step, but the overall savings in time and costs over the
basic process are more than offset.
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To fabricate a bit from a casting, a mold is
prepared by machining a cavity in a cylinder of graphite,
reproducing a negative of the bit profile in the exact
dimensions of the body of the bit. Cutting elements axe
located and the fluid passageways are traced in the
interior of the mold. Cutting elements and nozzle
openings, plus fluid circulation channels, are prepared
from a material destructible after firing of the mold in
a furnace. The various elements utilized in producing a
mold are subsequently destroyed after the casting process
thereby resulting in a bit body having shaped cutting
element receptacles in the head of the bit.
Recently, techniques have been developed for
generating three-dimensional objects within a fluid
medium which is selectively cured by beams of radiation
brought to focus at prescribed intersection points within
the three-dimensional volume of the fluid medium. These
techniques utilize a process known as "stereolithography"
as a method for making solid objects by successfully
generating thin layers of a curable material one on top- _.
of the other in response to a programmed movable beam of
light directed to a surface or layer of the curable
liquid. Each layer formed in the curable liquid is a
solid cross section of the object at the surface of the
curable liquid. The process of generating layers in
cross section of an object is continued until the entire
object is formed in the curable liquid.
Use of stereolithography has become known as a
"rapid prototyping process." The first industries to
utilize the rapid prototyping process were manufacturers
of aircraft modular units that specialized in the design
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and manufacture of interior components for military and
commercial aircraft. Major applications now include
rapid prototyping and product tooling in the automotive,
aerospace, medical, computer, electronic and consumer
product industries. A leader in the field of rapid
prototyping is 3D Systems Inc, of San Gabriel,
California. 3D Systems Inc. has numerous United States
patents directed to various inventions relating to rapid
prototyping utilizing stereolithography.
A recent improvement in rapid prototyping in the
manufacture of products is the utilization of a CAD
system that when combined with , rapid prototyping
substantially reduces the time and cost of bringing new
products to market, reference is made to United States
Patent No. 5,544,550 issued August 13, 1996, United
States Patent No. 6,200,514 B1 issued March 13, 2001,
United States Patent No. 6,209,420 Bl issued April 3,
2001, and British Patent No. GB 2,296,673.
However, there continues to be a need in the design
and production of tools for earth boring that rapidly and
reliably moves from a design stage to a prototype stage
and ultimately the fabrication of tools while moving
directly from computer designs to production and
fabrication of finished tools.
Engineers and production managers in the earth
boring industries have long investigated and searched for
rapid, reliable, economical and automatic means to
facilitate manufacture of tools for earth boring moving
from a design stage to the prototype stage and to the
production and fabrication, while avoiding the
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complicated painstaking procedures utilized in the basic
machine process and the casting process described above.
SUMMARY OF THE INVENTION
The present invention is a method of fabricating a
tool for earth boring comprising creating a CAD data base
of parts for a desired tool. Utilizing the CAD data
base, a prototype of molds of the tool parts is
fabricated. The mold is then prepared for casting of the
tool part, for example, a drill bit body. The prepared
mold is filled with a material selected for the drill bit
body and the filled mold is then processed into a tool
part.
More specifically, after optimizing the design of
the tool parts by operation of a computer program that
designs both mechanical and fluid flow specification, the
computed results are integrated into a CAD code. A rapid
prototyping file is generated and depending on the type
of tool part to be manufactured, the file contains either
a female geometry of the tool parts. The corresponding
mold is then manufactured utilizing a rapid prototyping
process such as stereolithography, fretted metal by
laser, or strata of paper cut by laser.
Further, in accordance with the present invention,
there is provided a method for fabricating a component of
a drill bit for earth boring comprising creating a CAD
data base comprising a design of the component of the
drill bit and then prototyping a mold of the design of
the drill bit component from the created CAD database.
The prototype mold is prepared for casting utilizing
either a male mold or a female mold, the latter
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considered a "master-mold." Following preparation of the
mold for casting, the mold is filled with a material
selected for the drill bit component and the filled mold
is fired in a furnace to solidify the selected material
5 into a component of the drill bit. Following preparation
of the mold for casting, the mold is filled with a molten
material and the selected material is solidified into a
component of the drill bit.
In accordance with the present invention, various
tools for earth boring may be fabricated using the rapid
prototyping method. Complex forms are easily created by
using a computer to generate the program commands as a
CAD file that sends the signals to the fabrication
system. Although the invention will be described with
reference to fabrication of a drill bit for earth boring,
it also finds utility in the fabrication of other tools
for earth boring.
A technical advantage of the present invention is
the fabrication of earth boring tools using an efficient
fabrication process that saves considerable time, effort
and expense. The present invention also has the
technical advantage of readily modifying a tool design
for specialized application that results in improved
cutting features. The parts fabricated in accordance
with the present invention are readily machined to a
final specification for fabrication into a complete tool
for earth boring.
BRIEF DESCRIPTION OF THE DRAWINGS
For a more complete understanding of the present
invention and the advantages thereof, reference is now
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made to the following description, taken in connection
with the accompanying drawings:
FIGURE 1 is a top view of a steel body drag bit
fabricated in accordance with the process of the present
invention;
FIGURE 2 is a side view of the drag bit of FIGURE 1;
FIGURE 3 is a pictorial illustration of a system for
performing the process of the present invention;
FIGURE 4 is a top level flowchart of the process for
manufacturing a drill bit for earth boring utilizing
rapid prototyping of a mold for the drill bit body;
FIGURE 5 is a flowchart of one embodiment of the
process of the present invention for fabrication of a
tool bit utilizing rapid prototyping of a female mold;
FIGURE 6 is a flowchart of an alternate embodiment
of the process of the present invention for manufacturing
a drill bit utilizing rapid prototyping of a female mold;
FIGURE 7 is a flowchart of an alternate embodiment
of the process of the present invention for manufacturing
a drill bit utilizing rapid prototyping of a female mold;
FIGURE 8 is a pictorial illustration of selective
laser sintering for rapid prototyping of molds for drill
bit fabrication in accordance with the process of the
present invention; and
FIGURE 9 is a pictorial illustration of a paper cut
by laser process for rapid prototyping a mold for the
fabrication of a drill bit body in accordance with the
present invention.
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DETAILED DESCRIPTION OF THE DRAWINGS
Referring to FIGURES 1 and 2, there is shown a drill
bit body 10 fabricated in accordance with the rapid
prototyping process of the present invention. As
illustrated, the bit body l0 includes cavities for fixed
cutters and is conventionally referred to in the industry
as a drag bit. It should be understood that the process
of the present invention is not limited to drag bits but
finds utility for other drill bits for earth boring and
in addition for the fabrication of other tools for earth
boring.
As best illustrated in FIGURE 2, the drill bit ZO
comprises a bit body 12, a shank 14 and a threaded
connection or pin 16 for connecting the drill bit to a
sub or as part of a drill string (not shown) in a manner
conventional for drilling in formations of the earth.
The bit body 12 includes a central longitudinal bore
(not shown) as is conventional with drill bit
construction as a passage for drilling fluid to flow
through the drill string into the bit body and exit
through nozzles (not shown) arranged in the operating end
face 20. Extending radially from essentially the center
of the operating end face 20 are circumferentially spaced
blades 22 that extend down the side of the bit body 12 to
the shank 14. The end of the blades 22 at the shank 14
function as gauge pads. The bit body 12 is formed in
accordance with the process of the present invention
typically utilizing powdered metal tungsten carbide (a
matrix bit body) or a molten metal casting process.
As best illustrated in FIGURE 1, formed in each of
the blades 22 of the bit body 12 is a pattern of pockets
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24 that receive primary cutting elements as is
conventional in drag bit assembly. The pockets 24 along
with the passage for drilling fluid are fabricated during
the process of the present invention for fabricating the
bit body 12.
Referring to FIGURE 3, there is pictorially
illustrated a stereolithographic system for generating
complex geometry three dimensional drill bit parts by
creating a cross-sectional. pattern of the drill bit
geometry at a surface of a fluid medium capable of
physical state alteration in response to appropriate
synergistic stimulation. A programmed movable spot beam
of light from a laser 30 passing through a laser scanner
32 impinges on a surface or layer of curable liquid in a
photopolymer vat 34. The laser scanner 32, the
photopolymer vat 34 and a Z-axis elevator 36 along with
controlling computers 38, 40 and 42, comprise together a
stereolithography system for creating complex geometry
drill bit parts. The stereolithography system of FIGURE
3 represents a technique to quickly make complex geometry
drill bit parts without conventional tooling.
To create the complex drill bit parts, a computer
program is run in the computer 42 to optimize a bit
design including both mechanical components and fluid
passageways. This design is integrated into a computer
aided design (CAD) code in a computer 40. A rapid
prototyping file is generated from the CAD code in a
computer 40. Depending on the type of bit to be
manufactured, the rapid prototyping file contains either
the female or the male geometry of the drill bit parts.
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The computer 38 then provides drive signals to the laser
30, the laser scanner 32, and the Z-axis elevator 36.
The stereolithographic system of FIGURE 3 has many
advantages over currently used apparatus fox producing
complex geometry drill bit parts. The system as
illustrated in FIGURE 3 minimizes the need for producing
design layouts and drawings and tooling drawings and
tooling. A drill bit engineer works directly with the
computer 42 and the stereolithographic equipment of
FIGURE 3 and when satisfied with the design of a drill
bit part as displayed on the monitor of the computer 42,
a mold for the part is fabricated in the photopolymer vat
34 for an immediate analysis and examination. If the
design requires modification, such modification is easily
accomplished through the computer 42 and another mold for
a prototyping part is fabricated to verify the change in
a desired drill bit design. Inasmuch as earth boring
tools require many parts with interacting functions, the
method of rapid prototyping as described herein becomes
even more useful because all of the part designs may be
quickly changed and made again so that the total assembly
may be examined, repeatedly if necessary. After the
design is complete, part production begins immediately,
weeks and months between design and production are
avoided.
As mentioned, depending on the type of bit to be
manufactured, the rapid prototyping file in the computer
38 contains either a female or a male mold geometry of
the drill bit parts. If the rapid prototyping file
contains a female mold design, this female mold as
created in the photopolymer vat 34 is subsequently
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utilized to manufacture a male former or used directly to
manufacture the bit. In the case of the direct use of
the female mold, the female former is filled and cured in
a furnace for a matrix body bit or the female former is
filled with a molten metal material in the case of a
steel body bit.
If the rapid prototyping file contains a male mold
design, the rapid prototyping male mold from the
photopolymer vat 34 is mounted on a burnable pattern and
the mold along with the burnable pattern is covered with
a slurry of hardenable, refractory material. The coated
pattern is placed in a dryer to harden the refractory
material to form a ceramic shell and simultaneously burn
out the burnable pattern and the rapid prototype female
mold. The resulting female former, preferably of a
ceramic material, is either placed in a supporting bed
and filled with a molten metallic material, or a matrix
powder with a binder. For a matrix body bit, the filled
female former is cured in a furnace to create the desired
drill bit part. For a steel body bit, the ceramic mold
is filled with a molten steel to create the desired drill
bit part. After the molten metal has cooled to
solidification, the ceramic male former is broken away to
expose the drill bit part having the desired complex
form.
Also by way of example, the rapid prototyping female
mold from the photo multiplier vat 34 is filled with a
molten metallic material or with a matrix powder and a
binder. For a matrix body bit, the filled female mold is
cured in a furnace to create the desired drill bit part.
For a steel body bit, the female mold is filled with a
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molten steel to create the desired drill bit part. In
either application, either the matrix body bit or the
steel body bit, after the material has solidified the
female mold is broken away to expose the drill bit part
having the desired complex form.
Alternatively, when the rapid prototyping file
contains a design for a female mold, the mold created is
utilized to manufacture a male former called a "master-
mold." This master-mold is then utilized to manufacture
a destructible sand shell. The sand shell is filled with
the desired matrix and binder material and placed in a
furnace for hardening. For a steel body bit, the shell
is filled with a molten metal and allowed to harden.
Referring to FIGURE 4, there is illustrated a flow
diagram of the process for manufacturing a drill bit
utilizing the rapid prototyping of a mold as illustrated
and described with reference to FIGURE 3. Initially, by
use of the computer 42, a designer optimizes the drill
bit design in a design operation 44. The optimized drill
bit design from operation 44 is integrated into CAD code
in the computer 40 by operation 46. The CAD code is then
utilized to generate a prototype file in the computer 38
in operation 48. Output signals from the computer 38
utilizing the prototype file actuate the laser 30, the
laser scanner 32 and the Z-axis elevator 36 to rapid
prototype a mold for a drill bit part in operation 50.
When the rapid prototyping mold from operation 50 meets
the design specification for a drill bit, the mold is
used in a conventional process to manufacture the drill
bit part during operation 52. The various parts of a
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drill bit are then assembled into a fabricated drill bit
of the type illustrated in FIGURES 1 and 2.
Referring to FIGURE 5, there is illustrated a flow
chart of the process for creating a female mold from the
rapid prototyping system as illustrated in FIGURE 3. As
discussed with reference to FIGURE 4, initially the drill
bit design is optimized in a CAD system during operation
54. Utilizing the rapid prototyping file in the computer
38, a rapid prototyping female mold is created in the
polymer vat 34 during operation 56. Utilizing the female
mold during an operation 62, the rapid prototyping mold
is filled with a molten metallic material for a steel bit
body or with matrix powder and binder. For a matrix
powder and binder bit body, the filled female mold is
placed in a furnace during operation 64 to melt the
binder and infiltrate the matrix powder. Following
operation 64 for a matrix bit or following operation 62
for a steel body bit, the material is cooled in a
operation 66 and the rapid prototyping female mold is
broken away to expose the drill bit part having the
desired complex design.
Referring to FIGURE 6, there is illustrated a flow
diagram for fabricating drill bit parts utilizing the
rapid prototyping of a female mold. As previously
explained, initially the drill bit design is optimized in
a CAD system during operation 108. Utilizing the
stereolithography system of FIGURE 3 a supple female mold
is rapid prototyped during operation 110. It should be
noted that other rapid prototyping processes can also be
used such as selective laser sintering (SLS); fused
deposition modeling (FDM), laminated object manufacturing
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(LOM), ballistic particle manufacturing (BPM), and 3D
printing.
After removing the rapid prototype mold from the
photopolymer vat 34, the mold is filled with a resilient
material in an operation 112 to produce a male former.
The resilient material in the female mold is dried during
an operation 114 to produce a male former. During an
operation 116, the male former is coated with a
hardenable and refractory material in an operation 116
and the male former is removed leaving a resulting shell
mold.
The shell resulting from the operation 116 is filled
with a molten metallic material or with a matrix powder
and binder in an operation 118. For the matrix powder
and binder, the filled shell is placed in a furnace to
melt the binder and infiltrate the matrix powder during
an operation 120. For a steel body bit and for the
matrix body bit, the last operation to fabricate a drill
bit part is completed in an operation 122.
Referring to FIGURE 7, there is illustrated a flow
diagram for fabricating drill bit part utilizing the
rapid prototyping of a female mold. Again, initially the
drill bit design is optimized in a CAD system during
operation 68. Utilizing the stereolithography system of
FIGURE 3, the female mold is rapid prototyped during
operation 70. After removing the rapid prototype mold
from the photopolymer vat 34, the mold is filled with a
resilient material to produce a male pattern (master-
mold) of the bit design during operation 72. The
resilient material in the female mold is dried during an
operation 74 to produce the master male former. During
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an operation 76 the male former is coated with a mix of
sand and resin during operation 76. The mix of sand and
resin is dried in an operation 78 to produce a shell by
removing the rapid prototyping mold.
Following the operation 78, the process for
manufacturing drill bit parts using a female mold is the
same as illustrated and described with reference to
FIGURE 5 utilizing the described mold. The shell
produced by the operation '78 is filled with a metallic
material (a steel body bit) or with matrix powder and a
binder in an operation 80. For the matrix powder and
binder (a matrix body bit), the filled shell is placed in
a furnace to melt the binder and infiltrate the matrix
powder during an operation 82. For a steel body bit and
for the matrix body bit, the last operation to fabricate
a drill bit part is completed in operation 84.
It will be appreciated that other forms of
appropriate synergistic stimulation for a curable medium
are available in addition to the stereolithography system
of FIGURE 3. Referring to FTGURE 8, there is pictorially
illustrated a process for selective laser sintering (SLS)
to create a rapid prototype mold for parts of a drill
bit. The drill bit design for use with the process of
FIGURE 8 is optimized by the computers 38, 40 and 42 as
illustrated in FIGURE 3 and described with reference to
FIGURE 4. The output of the computer 38 actuates a C02
laser 86, a laser scanner 88 and a precision roller
mechanism 90. A layer of powder 92, for example, a resin
(polystyrene polycarbonates), a metallic or a ceramic, is
deposited in a powder bed 94. The powder is supplied
from a powder cartridge (not shown) typically contained
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within the housing 96. The powder can be selected from
other ceramic materials, such as, alumina, zircon oxides
(ALz03, Si02, Zr02) , carbides (SiC, B4C and others) ,
nitrous (Si3N4, A1N, BN), or gains of these materials
5 coated with a binder.
The precision roller mechanism 90, comprising a
linearly extending feedhead is horizontally moved across
and above the powder bed to spread a thin layer of
powdered selective laser sintering (SLS) material across
10 the build platform. Using data from the computer 38 the
C02 laser 86 in conjunction with the laser scanner 88
selectively draws a cross section of the drill bit part
on the layer of powder in the powder bed 94. As the
laser beam is drawn across the section, it selectively
15 "sinters" (heats and fuses) the powder creating a solid
mass that represents one cross section of the drill bit
mold part. Only the heated grains of the powder
participate in the development of the cross section with
the grains of powder surrounding the part acting to
support the following layers of the part being created by
rapid prototyping.
The process for creating a rapid prototype part
utilizing the selective laser sintering (SLS) system of
FIGURE 8 repeats the process of spreading the powder by
means of a precision roller mechanism 90 and sintering
layer after layer of the powder 92 until the complete
object is created. Once the part is completed, it is
removed from the build chamber of the housing 96 and any
loose powder is blown away. The rapid prototype mold
created by the system of FIGURE 8 is then utilized to
manufacture drill bit parts the same as the molds created
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by the system of FIGURE 3. Either a female mold or a
male mold will be created and drill bit parts fabricated
in accordance with the description of FIGURES 4, 5, 6,
and 7. The selective laser sintering (SLS) process
represents a remarkable evolution in the rapid
prototyping of three-dimensional objects.
Another process for creating a rapid prototyping
mold for drill bit parts is a paper cut by laser process.
Referring to FIGURE 9, there is pictorially illustrated a
laminated object manufacturing (LOM) process for the
formation of three dimensional objects. A laser 100 and
a laser scanner 102 receive command signals from the
computer 38 as illustrated in FIGURE 3. The process of
FIGURE 9 utilizes the rapid prototyping file resident in
the computer 38 resulting from optimizing a drill bit
design by means of the computer 42 and the computer 40 of
FIGURE 3.
In accordance with the laminated object
manufacturing (LOM) process, the system of FIGURE 9
deposits layers of "thermal-adhesive" paper on a platen
support 104 and these pieces of paper are cut by the
light beam emitting from the laser 100 in a pattern as
determined by positioning of the X-Y laser scanner 102.
Each layer of paper deposited on the platen 104 forms a
cross section of the three-dimensional object created by
the laminated object manufacturing (LOM) process. Upon
completion of cutting of one layer of paper, an
additional layer is placed on the platen 104 from a
supply roll 106. This process of cutting the deposited
layer of paper by means of the laser 100 as controlled by
the X-Y laser scanner 102 continues until a compact block
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of paper is supported on the platen 104. As illustrated
in FIGURE 9, a three-dimensional object, e.g., a mold for
a drill bit part, is in the center of the compact block
of paper on the platen 104. It is therefore necessary to
clear the cutting surrounding the object to reveal the
mold for manufacture of drill bit parts.
The resulting mold from operation of the system of
FIGURE 9 is either a female mold or a male mold as
previously described. These molds are utilized in
accordance with the processes of FIGURES 4, 5, 6 and 7 to
fabricate drill bit parts in accordance with an optimized
design. For a more complete description of the laminated
object manufacturing (LOM) process, reference is made to
United States Patent No. 4,752,352, issued June 21, 1998,
and U.S. Patent No. 5,01S,312 issued May 14, 1991, and
PCT publication WO 95/18009 published July 6, 1995.
It will be understood from the foregoing that,
although particular embodiments of the invention have
been..illustrated and described, various modifications can
be made without the departing from the invention as set
forth in the appended claims.
