U.S. patent application number 13/407914 was filed with the patent office on 2013-08-29 for additive fabrication technologies for creating molds for die components.
This patent application is currently assigned to Ford Motor Company. The applicant listed for this patent is Larry Edward Ellis, Ronald Hasenbusch, Alan Lawrence Jacobson, James Todd Kloeb, Evangelos Liasi, John Philips, Harold P. Sears. Invention is credited to Larry Edward Ellis, Ronald Hasenbusch, Alan Lawrence Jacobson, James Todd Kloeb, Evangelos Liasi, John Philips, Harold P. Sears.
Application Number | 20130220570 13/407914 |
Document ID | / |
Family ID | 48951036 |
Filed Date | 2013-08-29 |
United States Patent
Application |
20130220570 |
Kind Code |
A1 |
Sears; Harold P. ; et
al. |
August 29, 2013 |
ADDITIVE FABRICATION TECHNOLOGIES FOR CREATING MOLDS FOR DIE
COMPONENTS
Abstract
A method comprising the use of additive manufacturing techniques
for creating molds and pattern parts for subsequent use in the
casting of die components and die shoes for use in die stamping
processes.
Inventors: |
Sears; Harold P.; (Livonia,
MI) ; Kloeb; James Todd; (Armada, MI) ; Liasi;
Evangelos; (Royal Oak, MI) ; Ellis; Larry Edward;
(Dearborn Heights, MI) ; Hasenbusch; Ronald;
(Grosse Pointe Park, MI) ; Philips; John; (Ann
Arbor, MI) ; Jacobson; Alan Lawrence; (Ann Arbor,
MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Sears; Harold P.
Kloeb; James Todd
Liasi; Evangelos
Ellis; Larry Edward
Hasenbusch; Ronald
Philips; John
Jacobson; Alan Lawrence |
Livonia
Armada
Royal Oak
Dearborn Heights
Grosse Pointe Park
Ann Arbor
Ann Arbor |
MI
MI
MI
MI
MI
MI
MI |
US
US
US
US
US
US
US |
|
|
Assignee: |
Ford Motor Company
Dearbon
MI
|
Family ID: |
48951036 |
Appl. No.: |
13/407914 |
Filed: |
February 29, 2012 |
Current U.S.
Class: |
164/34 ; 164/15;
164/6 |
Current CPC
Class: |
B33Y 10/00 20141201;
B22C 9/04 20130101; B22C 9/06 20130101; B33Y 80/00 20141201; B29C
64/182 20170801; Y02P 10/292 20151101; B33Y 70/00 20141201; Y02P
10/25 20151101; B22C 9/10 20130101; B22C 9/08 20130101; B22F 3/1055
20130101; B29C 64/165 20170801; Y02P 10/295 20151101 |
Class at
Publication: |
164/34 ; 164/6;
164/15 |
International
Class: |
B22C 9/04 20060101
B22C009/04; B22C 9/10 20060101 B22C009/10; B22C 9/02 20060101
B22C009/02 |
Claims
1. A method of making a pattern part for use in casting a die
component, comprising: (a) depositing a thin layer of polymeric
powder on a build platform; (b) selectively applying a solvent to
particular regions of the thin layer of polymeric powder to bind
the polymeric powder in said regions to define a cross-section of
the pattern part; repeating steps (a) and (b) to produce a
completed pattern part having a configuration of the die component;
coating the pattern part with a slurry to form a shell about the
pattern part; heating the shell to harden the shell and vaporize
the pattern part to create a shell comprising a negative image of
the pattern part; and casting a molten material into the shell to
form the die component.
2. The method of claim 1, wherein the step of depositing a thin
layer of polymeric powder on a build platform further comprises:
depositing a layer of polymeric powder comprising poly(methyl
methacrylate).
3. The method of claim 2, wherein the step of selectively applying
a solvent to particular regions of the thin layer of polymeric
powder further comprises: jetting droplets of the solvent on the
thin layer of polymeric powder using a print head.
4. The method of claim 3, further comprising: curing the pattern
part.
5. The method of claim 4, further comprising: impregnating the
pattern part with a wax resin to seal the pattern part.
6. The method of claim 1, wherein the step of coating the pattern
part with a slurry to form a shell about the pattern part further
comprises: coating the pattern part with a ceramic slurry.
7. The method of claim 4, further comprising: dipping the pattern
part in a fluidized bed of sand after coating the pattern part with
the ceramic slurry.
8. The method of claim 1, wherein the step of casting a molten
material into the shell to form the die component further
comprises: forming a die component having a near net-shape of the
pattern part within an accuracy range of 1 mm to 5 mm.
9. A method of making a die component, comprising: forming a mold
core package using an additive manufacturing process, wherein the
mold core package comprises a negative image of the die component;
casting a molten material into the mold core package; and cooling
the molten material to form the die component having a near net
configuration of the mold core package within an accuracy range of
1 mm to 5 mm.
10. The method of claim 9, wherein the set of forming a mold core
package using an additive manufacturing process further comprises:
(a) depositing a thin layer of particulate; (b) selectively
applying a binder to the thin layer to define a cross-section of a
mold core package; and repeating steps (a) and (b) to produce a
completed mold core package.
11. The method of claim 10, wherein the step of selectively
applying a binder to the thin layer to define a cross-section of a
mold core package further comprises: printing the binder on the
thin layer using a three-dimensional sandprinting device.
12. The method of claim 11, the step of cooling the molten material
to form the die component having a near net configuration of the
mold core package within an accuracy range of 1 mm to 5 mm further
comprises: forming a die component having a near net configuration
of the mold core package within 0.8 mm.
13. The method of claim 9, wherein the step of forming a mold core
package using an additive manufacturing process, wherein the mold
core package comprises a negative image of the die component
further comprises: forming a mold core package having a negative
image of attachment features for attaching the die component to a
die stamping assembly.
14. The method of claim 13, wherein the step of forming a mold core
package having a negative image of attachment features for
attaching the die component to a die stamping assembly further
comprises: forming a mold core package having a negative image of
bores and counter bores.
15. The method of claim 9, wherein the step of forming a mold core
package using an additive manufacturing process, wherein the mold
core package comprises a negative image of the die component
further comprises: forming a mold core package having a negative
image of a cutting edge.
16. A method of making a plurality of sand mold packages for use in
casting die components, comprising: printing a plurality of sand
mold packages using an additive 3D printer wherein the plurality of
sand mold packages comprises one or more die component
configurations ; nesting select sand mold packages from the
plurality of sand mold packages into a casting structure having
runners in communication with each select sand mold package;
casting a molten material into the casting structure to fill each
select sand mold package using the runners; and allowing the molten
material to cool to form said die components having a near net
configuration of each select sand mold package.
17. The method of claim 16, wherein the step of printing a
plurality of sand mold packages using an additive 3D printer
further comprises: printing a plurality of sand mold packages in a
range of about 80-150 sand mold packages in a single printing
process.
18. The method of claim 16, wherein the step of printing a
plurality of sand mold packages using an additive 3D printer
further comprises: printing runners in communication with each sand
mold package of the plurality of sand mold packages.
19. The method of claim 16, wherein the step of casting a molten
material into the casting structure to fill each select sand mold
package further comprises: casting tool steel into the casting
structure.
20. The method of claim 16, wherein the step of nesting select sand
mold packages from the plurality of sand mold packages into a
casting structure having runners in communication with each select
sand mold package further comprises: using a cope and drag assembly
to investment cast the molten material into the sand mold packages.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is related to the following applications:
U.S. patent application Ser. No. ______, filed on Feb. 29, 2012,
entitled "MOLD CORE FOR FORMING A MOLDING TOOL" (Atty. Docket No.
83203377); U.S. patent application Ser. No.______, filed on Feb.
29, 2012, entitled "MOLDING ASSEMBLY WITH HEATING AND COOLING
SYSTEM" (Atty. Docket No. 83203379); U.S. patent application Ser.
No. ______, filed on Feb. 29, 2012, entitled "INTERCHANGEABLE MOLD
INSERTS" (Atty. Docket No. 83203382); U.S. patent application Ser.
No. ______, filed on Feb. 29, 2012, entitled "MOLD CORE PACKAGE FOR
FORMING A POWDER SLUSH MOLDING TOOL" (Atty. Docket No. 83225801);
and U.S. patent application Ser. No. ______, entitled "MOLDING TOOL
WITH CONFORMAL PORTIONS AND METHOD OF MAKING THE SAME" (Atty.
Docket No. 83225806), the entire disclosures of which are hereby
incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention generally relates to the use of
additive manufacturing techniques for creating molds and pattern
parts for use in the casting of die components for use on die
assemblies, as well as for making molds for die shoes.
BACKGROUND OF THE INVENTION
[0003] Die components, such as trim steels, scrap cutters, flange
steels, form steels, pierce inserts, trim inserts, button block
inserts, and the like, are components of a stamping die assembly
that form and cut away excess sheet steel from a vehicle part, such
as a hood, door panel, or other like part being formed. There are
any number of die components used per stamping die assembly, each
one having a unique configuration and function. Thus, it is
impractical to cast multiple die components using traditional sand
casting methods, which involve tooling up a mold pattern to form a
sand core from which the die component is cast. The present
invention provides techniques to create a pattern part or a mold
core package that can later be used in the casting process to cast
one or more die components having a near net-shape of the finished
part. In this way, the present invention provides a cast part which
greatly reduces the amount of finishing work that needs to be
performed on the part after being cast. Further, the present
invention provides a method which involves less stock material to
cast the near net-shape die component part.
[0004] The common method for producing die components is through an
investment casting process, which involves a pattern maker gluing
Styrofoam.RTM. pieces together in an approximate shape of the die
component and then machining that Styrofoam.RTM. into the desired
shape and size of the die component to be cast. Recently, this
technology has been referred to as subtractive manufacturing and is
also used with metallic blocks or other such billets that are
machined down to the approximate shape of a die component. This
machining process lacks the precision needed to cast a near
net-shape of the die component. Thus, extra machining stock, as
much as 10 mm, is left on the subtractively manufactured pattern
part and the resulting casting. This extra casting stock must be
machined using a lengthy process, which involves scanning the
object and creating a CNC program that is based on the actual shape
of the desired part. Having the extra machining stock on the final
cast part requires multiple rough machining steps, especially when
a cutting edge is desired on the die component. The multiple rough
machine steps are necessary because the extra stock on the cast
part often exceeds the penetration depth of the CNC machine, such
that the extra stock must first be removed through any number of
rough cut operations. The part must be hardened between rough
machining processes and, finally, finish machined. The present
invention eliminates several of the post-casting steps involved in
making a finished die component.
SUMMARY OF THE INVENTION
[0005] According to one aspect of the present invention, a method
of making a pattern part for use in casting a die component
includes the steps of (a) depositing a thin layer of polymeric
powder on a build platform and (b) selectively applying a solvent
to particular regions of the thin layer of polymeric powder to bind
the polymeric powder in said regions to define a cross-section of
the pattern part. Steps (a) and (b) are repeated to produce a
completed pattern part having a configuration of the die component
to be cast. The pattern part is then coated with a slurry to form a
shell surrounding the pattern part. The shell is then heated to
harden the shell and vaporize the pattern part to create a shell
comprising a negative image of the pattern part. A molten material
is cast into the shell to form the die component.
[0006] According to another aspect of the present invention, a
method of making a die component includes the steps of forming a
mold core package using an additive manufacturing process, wherein
the mold core package comprises a negative image of the die
component to be cast. A molten material is cast into the mold core
package, and the molten material is cooled to form the die
component having a near net configuration of the mold core package
within an accuracy range of plus or minus 1 mm to 5 mm.
[0007] According to yet another aspect of the present invention, a
method of making a plurality of sand mold packages for use in
casting die components includes the steps of printing a plurality
of sand mold packages using an additive 3D printer wherein the
plurality of sand mold packages comprises one or more die component
configurations. Select sand mold packages from the plurality of
sand mold packages are nested into a casting structure having
runners in communication with each select sand mold package. A
molten material is cast into the casting structure to fill each
select sand mold package using the runners. The molten material is
then cooled to form the unique die components having a near net
configuration of each select sand mold package.
[0008] These and other aspects, objects, and features of the
present invention will be understood and appreciated by those
skilled in the art upon studying the following specification,
claims, and appended drawings.
BRIEF DESCRIPTION OF DRAWINGS
[0009] In the drawings:
[0010] FIG. 1 is a top perspective view of a job box or rigid
containment box prior to formation of sand mold packages by a
sandprinting device;
[0011] FIG. 2 is a top perspective view of the job box of FIG. 1 as
a layer of fine particulates is being spread in the job box;
[0012] FIG. 3 is a top perspective view of the job box of FIG. 1 as
a binder is being added in the printing area by a sandprinting
device to form cross-sectional layers of the sand mold
packages;
[0013] FIG. 4 is a top perspective view of the job box of FIG. 1
after several layers of a sand have been printed by a sandprinting
device;
[0014] FIG. 5 is a top perspective view of the job box of FIG. 1
with a fresh layer of fine particulates being spread over the print
surface of the job box;
[0015] FIG. 6 is a top perspective view of the job box of FIG. 1
after a plurality of mold core packages have been printed and the
job box removed from the printing device;
[0016] FIG. 6A is a perspective view of the plurality of mold core
packages as removed from the job box, wherein the mold core
packages are made from bound sand and excess unbound sand is
proposed to be removed;
[0017] FIG. 7 is a top perspective view of a cope and drag mold
assembly having printed sand mold packages nested therein;
[0018] FIG. 8 is a perspective view of a cast die component;
[0019] FIG. 9 is a perspective view of a die assembly having die
components affixed thereto; and
[0020] FIG. 10 is a flow chart representing an additive
manufacturing process for creating a pattern part.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0021] For the purposes of description herein, the terms "upper,"
"lower," "right," "left," "rear," "front," "vertical,"
"horizontal," and derivatives thereof shall relate to the invention
as oriented in FIG. 1. However, it is to be understood that the
invention may assume various alternative orientations, except where
expressly specified to the contrary. It is also to be understood
that the specific devices and processes illustrated in the attached
drawings, and described in following specification, are simply
exemplary embodiments. Hence, specific dimensions and other
physical characteristics relating to the embodiments disclosed
herein are not to be construed as limiting, unless expressly stated
otherwise.
[0022] The present invention eliminates many steps in the process
of making a die component due to its accuracy and automation, which
saves a great deal of time, materials, and costs in the
manufacturing of a die component. Using additive manufacturing or
additive fabrication techniques, the accuracy and automation of the
present invention allows for the elimination of several post-cast
processing steps to create the desired die components. According to
embodiments of the present invention, sacrificial dies and
sacrificial pattern parts are provided through various additive
manufacturing processes that manufacture the molds or pattern parts
three-dimensionally one layer at a time. Sacrificial materials used
in the additive manufacturing processes of the present invention
include epoxies, sand, sand-ceramic mixes, powdered metals, plastic
resins, and the like. In the additive manufacturing processes of
the present invention, a three-dimensional (3D) mold or pattern
part is assembled by producing and sequentially stacking thin
cross-sectional layers of the desired mold or part as generated in
an additive manufacturing machine. To create a three-dimensional
part used in the methods of the present invention, a CAD program or
other like computer-aided drawing software is used to create design
data of the mold or pattern part to be formed.
[0023] Types of additive manufacturing processes known in the art
include stereolithography apparatuses (SLA), 3D sandprinting, and
other three-dimensional printers, ink jet printers that bond layers
of powder material, plastic compositions using a bonding solvent,
metallic based powders using a laser sintering device, and many
other such processes known in the art that will be appreciated by
one skilled in the art. Thus, any such process may be suitable in
conjunction with the present invention in creating a sacrificial
pattern part of a die component or a sacrificial mold for a die
component without departing from the spirit of the present
invention.
[0024] One such rapid manufacturing process includes a sandprinting
process which will now be described. This method is commenced by
first acquiring a 3D data design using a CAD model program to
create a sand mold package for a die component which, as
exemplified below, will be in the form of a trim steel die
component. It is contemplated, however, that any such die component
can be created using this process. First a 3D image of the pattern
part is created using a CAD program. The pattern part or model is
then subtracted from a 3D CAD model to create a sand mold package
design. The resulting 3D model of the sand mold package is then
produced using the techniques as described with reference to FIGS.
1-6.
[0025] Referring now to FIGS. 1-6, a job box 40 formed from any
number of materials, including wood, metal, etc., is positioned
below a printing device 42. The job box 40 defines a print area 44
within which a mold core package will be formed from a plurality of
stacked particulate layers, as further described below. The
printing device 42 is capable of printing 3D molds, cores, and mold
core packages for use in the present invention.
[0026] As used throughout this disclosure, the term "mold core
packages" will refer to sand printed or otherwise formed molds that
are ready for casting of a molten material. The term "molds" will
refer to a component of the mold core package and the term "cores"
refers to an insert that is inserted into a mold for displacing
molten material as cast into the mold core package. Thus, the
combination of molds and cores creates a mold core package for
casting. For purposes of the description of the formation of mold
core packages or sand mold packages using the three-dimensional
printing process discussed below, a sand mold package 110 as shown
in FIG. 7 will be referenced for exemplary purposes only. It is to
be understood that several different sand mold packages can be
printed for casting other die components and such sand mold
packages can be printed simultaneously in a single printing
process.
[0027] The printing device 42 includes a hopper 46 at a deposition
trough 48, which lays a thin layer of activated fine particulate
50, such as silica sand, ceramic-sand mixes, etc., inside the print
area 44. The particulate 50 may be of any size, including 0.002 mm
to 2 mm in diameter. The printing device 42 also includes a binder
deposition device or binder dispenser 52. As disclosed in detail
below, the binder dispenser 52 sprays a thin layer of binder or
binding agent 16 in a configuration or pattern 80 of a single layer
of a desired sand mold package or sand core package. Repetition of
the layering of sand and spraying of binding agent 16 by the binder
dispenser 52 on the fine particulate 50 results in the production
of a three-dimensional sand mold package or sand core package from
a plurality of the stacked particulate layers. The 3D sand mold
package is manufactured additively over a length of time sufficient
to print each thin layer of the fine particulate 50 in succession,
such that each layer of bound particulate is further bound to
adjacent layers, to form a completed sand mold package. Each thin
layer of the completed sand mold package measures approximately
0.28 mm. The sand mold package will ultimately be used as a
sacrificial mold to fabricate a die component, such as the trim
steel 120 as shown in FIG. 8.
[0028] With specific reference to FIG. 1, a computer-aided design
(CAD) program is developed wherein the specific configurations of a
plurality of sand mold packages 100 (FIG. 6A) are entered and
loaded up on a computer 60, which is coupled to the printing device
42. The computer 60 feeds the information from the CAD program with
the specific configurations of the plurality of sand mold packages
100 to the printing device 42 for formation of the sand mold
packages 100.
[0029] It is contemplated that CAD, or any other form of 3D
modeling software, can be used to provide sufficient information
for the 3D printing device 42 to form the desired sand mold
packages 100. Prior to activation of the 3D printing device 42, a
predetermined quantity of the fine particulates 50 is dumped into
the hopper 46 by a particulate spout 62, along with an activation
coating or activator 70 supplied by an activator spout 72. Although
the illustrated embodiment uses a fine sand, such as the fine
particulate 50, as noted above, the fine particulate 50 may include
any of a variety of materials or combinations thereof suitable for
the additive manufacturing techniques disclosed herein. The fine
particulates 50 are mixed in the hopper 46 with the activator 70.
The mixture of fine particulates 50 and activator 70 may be mixed
by an agitator 74 or other known mixing device such that the fine
particulates 50 become thoroughly mixed and activated. After the
fine particulates 50 and activator 70 have been thoroughly mixed,
the fine particulates 50 are moved to the deposition trough 48.
[0030] Referring now to FIGS. 2-6, after the fine particulates 50
have been moved to the deposition trough 48, the fine particulates
50 are spread across the print area 44 in a thin even layer of
unbound sand 90 by the deposition trough 48. After being spread in
a thin layer on the print area 44 in the job box 40, the activated
fine particulates 50 are sprayed with the binder or binding agent
16 (FIG. 3). The binding agent 16 is dispensed from the binder
dispenser 52, which sprays a thin layer of the binding agent 16 in
a pattern 80 that represents a first thin cross-sectional layer of
the desired sand mold packages 100. After the binding agent 16 has
been sprayed, another mixture of fine particulates 50 and activator
70 is prepared and dumped into the deposition trough 48. The
deposition trough 48 then dispenses another layer 90 of unbound
activated fine particulates 50 over the previously spread fine
particulates 50 layer in the job box 40, as shown in FIG. 5. The
binder dispenser 52 passes over the print area 44 again, spraying a
thin layer of the binding agent 16 in the pattern 80 that
represents a second thin cross-sectional layer of the desired sand
mold packages 100 adjacent to the first thin cross-sectional layer.
These steps are repeated many times until every thin
cross-sectional layer of the completed sand mold package 110 (FIG.
7) has been printed. Using this additive manufacturing technique,
virtually any shape of a sand mold package can be formed. Further,
a sand mold package produced using 3D sandprinting can have
internal structural features that cannot otherwise be created by
other known subtractive methods.
[0031] As shown in FIG. 3, the exemplified sandprinting process as
described above is creating a plurality of sand mold packages 100
which will be used as molds for forming die components. Thus, the
printing process described above is capable of printing several
different sand mold packages in a single print session for use in
casting a variety of unique die components. With the precision and
accuracy of the 3D sandprinting technology, anywhere from 80 to 150
sand mold packages can be printed in a single printing process.
Thus, as shown in FIG. 6A, a plurality of sand mold packages 100
are shown having been printed with the additive manufacturing
process as described above, and unbound sand is removed to reveal
the individual sand mold packages, such as sand mold package 110
shown in FIG. 7, used to create a die component in the form of a
trim steel 120, as shown in FIG. 8.
[0032] Once the sand mold packages 100 have been printed, they are
removed from the job box 40 and then sent to a foundry to be cast.
The sand mold packages 100 can be unique molds for casting a
variety of die components wherein each sand mold package comprises
a negative image of the die component to be cast. As used
throughout this disclosure, the term "negative image" or "negative
configuration" refers to an image or configuration formed in a mold
that imparts a reciprocal positive image or configuration in the
part cast or otherwise formed from the mold. At the foundry, the
sand mold packages, such as sand mold packages 110-114 selected
from the plurality of printed sand mold packages 100, are nested
into a cope 116 and drag 118 frame apparatus or casting structure,
as shown in FIG. 7, where they are backed up with common foundry
sand and the die components cast. As shown in the example of FIG.
7, a cope mold 116 is shown having sand mold packages 110a-114a
nested therein. As further shown in FIG. 7, a drag mold 118 is
shown with correlating sand core packages 110-114 also nested
therein. During a casting process, an access point (not shown)
disposed on the top of the cope mold 116 is used to pore a molten
material into the cope and drag molds 116, 118 to fill the sand
mold packages 110-114 with the molten casting material. Generally,
for producing die components, tool steel is used as the molten
material. The tool steel is poured into the access point disposed
on the top of cope mold 116, which will then travel through a
series of runners which can extend through the cope mold 116 to the
drag mold 118 and then to the sand mold packages 110-114 to fill
the sand mold packages 110-114 to capacity. It is further
contemplated that the runners can be printed between adjacent sand
mold packages to allow communication of molten material from one
sand mold package to an adjacent sand mold package. One or more
risers (not shown) may be disposed on the top of the cope mold 116
to indicate when the molten material has filled the sand core
packages disposed in the cope and drag apparatus. When the molten
material solidifies and hardens in the sand mold packages, the cope
and drag molds 116, 118 are removed, and the sand core packages
110-114 are broken away or otherwise destroyed to reveal the cast
die components. The runner system used to fill the sand mold
packages 110-114 during the sand mold casting process are removed
from the cast die components, and the cast die components are then
scrubbed and cleaned to reveal a precision made and accurately
configured die component, which needs little or no finish machining
to function in a die assembly. As noted above, the 3D sandprinting
technique as described can also be used to create a die show sand
mold package for casting a die shoe 140 (FIG. 9) to which die
components can be attached for making a completed die assembly for
use in a stamping process.
[0033] The accuracy and precision of the casting of the die
components is within a range of accuracy of approximately 1-5 mm,
or more preferably plus or minus 0.8 mm. Thus, the cast die
components require very little extra machining stock, approximately
1 mm to 1.5 mm to be added. With the reduced amount of stock as
compared to standard sand casting methods, which produce
approximately 10 mm of extra machining stock, the cast die
components of the present invention can be hardened and ground at a
mounting base 122, shown in FIG. 8, and then finish machined. This
eliminates white light scanning, programming, rough machining,
hardening, transportation for hardening, and lapping of the
mounting base. Additionally, due to the accuracy of the casting,
the machining of cutting surfaces of a die component having a
cutting edge may be eliminated altogether.
[0034] The present invention imparts several benefits as compared
to the traditional casting process in that there is a significant
reduction of time-to-market because the timeline to produce a
completed die set can be reduced as much as 10 to 17 days. Another
significant benefit is the elimination of design constraints on the
die components. Since the sand mold packages are printed using the
additive manufacturing technique described above, traditional
limitations found in subtractive manufacturing are eliminated, such
that complex sand mold packages can be created for casting die
components having complex geometries and functionality. Further,
due to the accuracy of the casting, some features of the die
components, which currently require time consuming post-casting
machining, may be left as cast or require little to no finish
machining For example, bore holes 124 and counter bore holes 126,
as shown on the trim steel 120 of FIG. 8, can be cast as part of
the die component, and require little post-casting machining to
develop useable attachment apertures for attaching the trim steel
120 to a die shoe, such as a die shoe 140 shown in FIG. 9. To
create attachment features such as the bores 124 and counter bore
holes 126, as shown on the trim steel 120 of FIG. 8, the sand mold
packages can be printed with negative images of such attachment
features. Further, the sand mold packages can be printed with
negative images of other features of the die components such as
cutting edge 128 shown on the trim steel 120 of FIG. 8. The
flexibility of the present invention allows for die components to
be created with heat treat depth optimization features. Heat treat
depth optimization is currently dependent on the geometry and
thickness of the die component. The die components cast using the
methods of the present invention can have the complex geometry and
thickness required to optimize the heat treat depth. Casting flash,
which can be created during a casting process, is also eliminated
due to the accuracy of the sand core packages that are printed.
Generally, casting flash is produced during traditional sand
casting processes, and this casting flash must later be machined
off. The methods of the present invention greatly reduce or
eliminate altogether the amount of casting flash on a resulting
cast die component.
[0035] As described above, Styrofoam.RTM. or CNC machining of
billets can be used to create pattern parts which are later used to
form molds for casting die components. The present invention also
relates to using additive manufacturing techniques to create a
pattern part which is later used for the creation of a mold for
casting a die component. Of the additive manufacturing techniques
mentioned above, one preferred process is an additive manufacturing
technique using a polymeric powder containing poly(methyl
methacrylate) (PMMA) as a base building material to form a
polymeric pattern part. As used throughout this disclosure, the
additive manufacturing process using the PMMA powder will be
referred to as the PMMA process. One of ordinary skill in the art
will appreciate that other additive manufacturing techniques can be
used to create a pattern part for later use in a casting
process.
[0036] As shown in FIG. 10, the PMMA process involves the use of an
STL or CAD file to produce 3D design data of a pattern part from a
computer 200. The pattern part, such as pattern part 220 shown in
FIG. 10, will have a configuration of the die component part to be
cast. Using the computer generated design data, a recoater 202
spreads a thin layer of PMMA powder 204 over a build platform 206.
The spreading of the PMMA powder is conceptually similar to the
spreading of the fine particulate 50, as noted with reference to
FIGS. 1-6. After a layer of PMMA powder 204 has been spread over
the build platform 206, a computer-controlled print head jets tiny
droplets of solvent or binder to bond the PMMA powder particles to
form a cross-sectional layer 208 of the pattern part. Once a
cross-sectional layer is complete, the build platform 206 is
lowered approximately 0.28 mm and another layer of PMMA powder 204
is spread over the build platform 206. The process is repeated
layer by 0.28 mm layer until the pattern part is completed. As
shown in FIG. 10, the pattern part 220 is essentially buried in
unbound PMMA powder 204 when the PMMA process is complete. This
unbound PMMA powder 204 is vacuumed or otherwise removed from the
pattern part 220 and can be reused in another PMMA process. Once
the pattern part 220 is complete, it can be post-cured in a low
temperature oven. It is contemplated that a job box, such as job
box 40 shown in FIGS. 1-6, can also be implemented in the PMMA
forming process to contain unbound PMMA powder. The pattern part
220 can then be impregnated with a wax resin to seal the pattern
part 220.
[0037] Once the pattern part is created, it is taken to a foundry
for the creation of a shell to be used in an investment casting
process. In order to use the pattern part in an investment casting
process, the part 220 is submerged or otherwise coated in a ceramic
slurry, which coats the entire part 220. The part is then dipped or
otherwise introduced into a fluidized bed of sand, ceramic-sand, or
other like powder material, which sticks to the liquid ceramic
slurry. Once the sand from the fluidized bed of sand has been
applied, the liquid ceramic slurry and sand mixture dries and
hardens, and the process is then repeated multiple times to form a
hard ceramic shell about and around the pattern part. Once a shell
of sufficient thickness is formed, the shell containing the pattern
part is then heated, such that the polymeric pattern part disposed
within the ceramic shell burns away or vaporizes. Thus, after the
heating process, the operator is left with a ceramic shell
comprising a negative image of the pattern part. Using an
investment casting or shell casting process, molten material, such
as tool steel, is poured into the ceramic shell having the negative
image of the pattern part. After the molten material solidifies,
the ceramic shell is broken away or otherwise destroyed to reveal
the cast metal part which, in accordance with the present
invention, would be a die component, such as die component 120
shown in FIG. 8.
[0038] Using this PMMA process, an accurate and precise pattern
part representing a die component can be made layer by layer, such
that complex geometries can be formed within the pattern part to
produce a die component cast having a near net-shape of the pattern
part. As noted above with the three-dimensional sandprinting
process, the PMMA process also reduces the post-casting rough
machining and finishing steps that are often required to make a
finished die component. Die components cast using the PMMA pattern
part as described above can have an near net-shape of the pattern
part within an accuracy range of approximately 1-5 mm. Further, it
is contemplated that the range of accuracy can be within plus or
minus 0.8 mm of the pattern part from which the shell is
formed.
[0039] The mold core packages and methods of making tools from the
mold core packages, such as, but not limited to, die components, as
disclosed herein provide an improved ability create configurations
with an optimized wall thickness and heat treat depth as needed,
thereby reducing the potential for warpage, cracks, etc. In
addition, the accuracy associated with making the mold core
packages from the printing process provides for better part
quality, precision, and design flexibility. Further, the mold core
packages and the die components made from the mold core packages
can be designed to improve cycle time, thereby increasing part
manufacturing capacity.
[0040] It will be understood by one having ordinary skill in the
art that construction of the described invention and other
components is not limited to any specific material. Other exemplary
embodiments of the invention disclosed herein may be formed from a
wide variety of materials and additive manufacturing techniques,
unless described otherwise herein.
[0041] It is also important to note that the construction and
arrangement of the elements of the invention as shown in the
exemplary embodiments is illustrative only. Although only a few
embodiments of the present innovation have been described in detail
in this disclosure, those skilled in the art who review this
disclosure will readily appreciate that many modifications are
possible (e.g., variations in sizes, dimensions, structures, shapes
and proportions of the various elements, values of parameters,
mounting arrangements, use of materials, colors, orientations,
etc.) without materially departing from the novel teachings and
advantages of the subject matter recited. For example, elements
shown as integrally formed may be constructed of multiple parts or
elements shown as multiple parts may be integrally formed, the
operation of the interfaces may be reversed or otherwise varied,
the length or width of the structures and/or members or connector
or other elements of the system may be varied, the nature or number
of adjustment positions provided between the elements may be
varied. It should be noted that the elements and/or assemblies of
the system may be constructed from any of a wide variety of
materials that provide sufficient strength or durability, in any of
a wide variety of colors, textures, and combinations. Accordingly,
all such modifications are intended to be included within the scope
of the present innovations. Other substitutions, modifications,
changes, and omissions may be made in the design, operating
conditions, and arrangement of the desired embodiment and other
exemplary embodiments without departing from the spirit of the
present innovations.
[0042] It will be understood that any described processes or steps
within described processes may be combined with other disclosed
processes or steps to form structures within the scope of the
present invention. The exemplary structures and processes disclosed
herein are for illustrative purposes and are not to be construed as
limiting.
[0043] It is also to be understood that variations and
modifications can be made on the aforementioned structure without
departing from the concepts of the present invention, and further
it is to be understood that such concepts are intended to be
covered by the following claims unless these claims by their
language expressly state otherwise.
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