U.S. patent application number 17/507556 was filed with the patent office on 2022-03-10 for method and system for software defined metallurgy.
This patent application is currently assigned to Desktop Metal, Inc.. The applicant listed for this patent is Desktop Metal, Inc.. Invention is credited to Animesh Bose, Brian D. Kernan, Mark Sowerbutts, Nihan Tuncer.
Application Number | 20220075334 17/507556 |
Document ID | / |
Family ID | |
Filed Date | 2022-03-10 |
United States Patent
Application |
20220075334 |
Kind Code |
A1 |
Tuncer; Nihan ; et
al. |
March 10, 2022 |
METHOD AND SYSTEM FOR SOFTWARE DEFINED METALLURGY
Abstract
A system for generating a user-adjustable furnace profile,
comprises a user interface configured to receive one or more
materials properties from a user, a processor, and a memory with
computer code instructions stored thereon. The memory is
operatively coupled to the processor such that, when executed by
the processor, the computer code instructions cause the system to
implement communicating with a furnace to ascertain one or more
thermal processes associated with the furnace, identifying one or
more object characteristics associated with an object to be
processed by furnace, and determining a thermal processing
parameter profile of at least one thermal processing parameter
corresponding to each of the thermal processes, based on (i) the
one or more part characteristics and (ii) the one or more materials
properties, the thermal processing parameter profile characterizing
a cycle of the one or more thermal processes.
Inventors: |
Tuncer; Nihan; (Cambridge,
MA) ; Kernan; Brian D.; (Andover, MA) ; Bose;
Animesh; (Burlington, MA) ; Sowerbutts; Mark;
(Townsend, MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Desktop Metal, Inc. |
Burlington |
MA |
US |
|
|
Assignee: |
Desktop Metal, Inc.
Burlington
MA
|
Appl. No.: |
17/507556 |
Filed: |
October 21, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16224432 |
Dec 18, 2018 |
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17507556 |
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15901265 |
Feb 21, 2018 |
10191456 |
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16224432 |
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62492744 |
May 1, 2017 |
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International
Class: |
G05B 15/02 20060101
G05B015/02; B22F 3/10 20060101 B22F003/10; G06F 3/0484 20060101
G06F003/0484; B33Y 30/00 20060101 B33Y030/00; B33Y 50/02 20060101
B33Y050/02; G06F 3/0482 20060101 G06F003/0482; B33Y 10/00 20060101
B33Y010/00; B22F 3/00 20060101 B22F003/00; F27D 19/00 20060101
F27D019/00; F27D 21/00 20060101 F27D021/00; B33Y 40/00 20060101
B33Y040/00; B22F 3/24 20060101 B22F003/24; B22F 10/10 20060101
B22F010/10 |
Claims
1. A method of generating a user-adjustable thermal processing
parameter profile for use by a furnace, comprising: by a processor
and a memory with computer code instructions stored thereon,
receiving, through a user interface, one or more materials
properties provided by a user; communicating with a furnace to
ascertain one or more thermal processes associated with the
furnace; identifying one or more part characteristics associated
with a part to be processed by furnace; and determining a thermal
processing parameter profile of at least one thermal processing
parameter corresponding to each of the thermal processes, based on
at least one of (i) the one or more part characteristics and (ii)
the one or more materials properties, the thermal processing
parameter profile characterizing a cycle of the one or more thermal
processes.
2. The method of claim 1, further comprising communicating with the
user through a graphical user interface, and, based on the
communicating, one or both of (i) guiding the user to an outcome of
a cycle of the thermal process and the materials properties of the
part and (ii) directing the user to the outcome of a cycle of the
thermal process and the materials properties of the part.
3. The method of claim 1, further comprising receiving and
implementing user direction regarding surface modifications to be
applied to the part in conjunction with the one or more thermal
processes being applied to the part.
4. The method of claim 3, further comprising notifying the user of
subsequent user direction that would conflict with the one or more
thermal processes corresponding to the first user direction, and
preventing the system from implementing changes associated with the
subsequent user direction that would conflict with the one or more
thermal processes corresponding to the first user direction.
5. The method of claim 1, further comprising receiving user input
configured to tailor the one or more process parameter profiles
according to specific result requirements.
Description
RELATED APPLICATIONS
[0001] This application is a divisional of U.S. application Ser.
No. 15/901,265, filed on Feb. 21, 2018 which claims the benefit of
U.S. Provisional Application No. 62/492,744, filed on May 1, 2017.
The entire teachings of the above applications are incorporated
herein by reference.
BACKGROUND
[0002] Additive manufacturing systems generally comprise several
processing steps, each of which may be accomplished by a different
subsystem. For example, an additive manufacturing system may
comprise a printing subsystem, one or more post-processing
subsystems and a furnace subsystem. The specific post-processing
procedures may vary depending upon the type of printing employed
(e.g., extrusion printing, binder jet printing, etc.).
[0003] The furnace subsystem may utilize a thermal processing
parameter profile that consists of one or more predetermined
thermal processing parameter profiles, each of which characterizes
an aspect of the processing that occurs in the furnace
subsystem.
SUMMARY OF THE INVENTION
[0004] The described embodiments may include a variable metallurgy
property (VMP) system for generating a user-adjustable thermal
processing parameter profile, which may be used by a thermal
processing furnace subsystem (also referred to herein as "furnace
subsystem") of an additive manufacturing system. As used herein,
the terms "thermal process" and "thermal processing" refer to a
process that comprises one or both of sintering and heat treatment
of a part. The term "part" refers to an article of manufacture,
e.g., an object or product.
[0005] A user may provide, to the VMP system, one or more desired
materials properties (and/or metallurgical characteristics) of a
final product to be processed by the furnace subsystem. The VMP
system may generate a thermal processing parameter profile for each
of one or more thermal processing cycles to be performed on the
part, based on the materials properties provided by the user. Each
thermal processing parameter profile describes how the furnace must
perform an aspect of the thermal process the furnace carries
out.
[0006] Embodiments of the VMP system may facilitate certain
ancillary processing procedures being accomplished during the
primary thermal processing cycle. For example, the VMP system may
facilitate one or more of annealing, aging, tempering and
stress-relieving of a part or parts being processed within the
additive manufacturing system.
[0007] In one aspect, the invention may be a system for generating
a user-adjustable thermal processing parameter profile for use by a
furnace. The system may comprise a user interface configured to
receive one or more materials properties provided by a user, a
processor, and a memory with computer code instructions stored
thereon. The memory may be operatively coupled to the processor
such that, when executed by the processor, the computer code
instructions cause the system to implement communicating with a
furnace to ascertain one or more thermal processes associated with
the furnace, and identifying one or more part characteristics
associated with a part to be processed by the furnace. The computer
code instructions may further cause the system to implement
determining a thermal processing parameter profile of at least one
thermal processing parameter corresponding to each of the thermal
processes, based on (i) the one or more part characteristics and
(ii) the one or more materials properties, the thermal processing
parameter profile characterizing a cycle of the one or more thermal
processes.
[0008] The materials properties may comprise at least one of (i)
hardness, (ii) ductility, (iii) microstructure, (iv) material
content, (v) surface property, and (vi) transverse rupture
strength. The thermal processing parameter profile may be a
function of time. The thermal processing parameter profile may be a
function of temperature. The thermal processing parameters may
comprise at least one of (i) temperature, (ii) furnace internal
atmosphere composition, (iii) chamber pressure, (iv) gas species,
(v) gas flow rate, and (vi) furnace load. The materials properties
from the user comprise characteristics of a completed part, and the
system determines the profile suitable to produce the
characteristics of the completed part.
[0009] The user interface may be a graphical user interface
configured to one or more of (i) receive the one or more materials
properties from the user, (ii) present guidance and options
concerning subsequent input from the user, and (iii) present
feedback to the user concerning each of the thermal processes.
[0010] The computer code instructions may further cause the system
to communicate with the user through a graphical user interface.
Based on the communicating, the computer code instructions may
cause the system to one or both of (i) guide the user to an outcome
of a cycle of the thermal process and the materials properties of
the part and (ii) direct the user to the outcome of a cycle of the
thermal process and the materials properties of the part.
[0011] The computer code instructions may further cause the system
to receive and implement user direction regarding surface
modifications to be applied to the part in conjunction with the one
or more thermal processes being applied to the part. A first user
direction associated with a first part may characterize the one or
more thermal processes for the cycle of the one or more thermal
processes. The computer code instructions may further cause the
system to one or both of (i) notify the user of subsequent user
direction that would conflict with the one or more thermal
processes corresponding to the first user direction and (ii)
prevent the system from implementing changes associated with the
subsequent user direction that would conflict with the one or more
thermal processes corresponding to the first user direction.
[0012] The computer code instructions may further cause the system
to receive user input configured to tailor the one or more process
parameter profiles according to specific result requirements.
[0013] The system may further include a binder trap configured to
store binder hydrocarbon products, and a valve that controls a path
from the binder trap to the sintering furnace, such that through
the valve, the binder hydrocarbon products may be selectively
introduced to the sintering furnace to control a carbon potential
of the sintering furnace environment.
[0014] In another aspect, the invention may be a method of
generating a user-adjustable thermal processing parameter profile
for use by a furnace. The method may comprise, by a processor and a
memory with computer code instructions stored thereon, receiving,
through a user interface, one or more materials properties provided
by a user. The method may further comprise communicating with a
furnace to ascertain one or more thermal processes associated with
the furnace, identifying one or more part characteristics
associated with a part to be processed by furnace, and determining
a thermal processing parameter profile of at least one thermal
processing parameter corresponding to each of the thermal
processes. The determining may be based on at least one of (i) the
one or more part characteristics and (ii) the one or more materials
properties. The thermal processing parameter profile may
characterize a cycle of the one or more thermal processes.
[0015] The method may further comprise communicating with the user
through a graphical user interface, Based on the communicating, the
method may further comprise one or both of (i) guiding the user to
an outcome of a cycle of the thermal process and the materials
properties of the part and (ii) directing the user to the outcome
of a cycle of the thermal process and the materials properties of
the part.
[0016] The method may further comprise receiving and implementing
user direction regarding surface modifications to be applied to the
part in conjunction with the one or more thermal processes being
applied to the part. The method may further comprise notifying the
user of subsequent user direction that would conflict with the one
or more thermal processes corresponding to the first user
direction, and preventing the system from implementing changes
associated with the subsequent user direction that would conflict
with the one or more thermal processes corresponding to the first
user direction.
[0017] The method may further comprise receiving user input
configured to tailor the one or more process parameter profiles
according to specific result requirements.
[0018] In another aspect, the invention may be a non-transitory
computer-readable medium with computer code instruction stored
thereon, the computer code instructions, when executed by an a
processor, may cause an apparatus to receive, through a user
interface, one or more materials properties provided by a user. The
computer code instructions may further cause the apparatus to
communicate with a furnace to ascertain one or more thermal
processes associated with the furnace, to identify one or more
object characteristics associated with an object to be processed by
furnace, and to determine a thermal processing parameter profile of
at least one thermal processing parameter corresponding to each of
the thermal processes. The determining of the thermal processing
parameter profile may be based on (i) the one or more part
characteristics and (ii) the one or more materials properties, the
thermal processing parameter profile characterizing a cycle of the
one or more thermal processes.
[0019] The computer code instructions, when executed by a
processor, may further cause the apparatus to communicate with the
user through a graphical user interface. Based on the
communicating, the computer code instructions may cause the
apparatus to one or both of (i) guide the user to an outcome of a
cycle of the thermal process and the materials properties of the
part and (ii) direct the user to the outcome of a cycle of the
thermal process and the materials properties of the part.
[0020] The computer code instructions, when executed by an a
processor, may further cause the apparatus to receive and implement
user direction regarding surface modifications to be applied to the
part in conjunction with the one or more thermal processes being
applied to the part.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The foregoing will be apparent from the following more
particular description of example embodiments of the invention, as
illustrated in the accompanying drawings in which like reference
characters refer to the same parts throughout the different views.
The drawings are not necessarily to scale, emphasis instead being
placed upon illustrating embodiments of the present invention.
[0022] FIG. 1A shows an example manufacturing system that may
employ the VMP system.
[0023] FIG. 1B illustrates an example embodiment of a VMP system
according to an aspect of the invention.
[0024] FIGS. 1C and 1D illustrate an example process workflow
according to the invention.
[0025] FIG. 2A shows an example user interface according to an
aspect of the invention.
[0026] FIG. 2B shows an example CCT diagram according to an aspect
of the invention.
[0027] FIGS. 3A and 3B show example gas flow channeling
architectures according to an aspect of the invention.
[0028] FIGS. 4A, 4B and 4C illustrate examples of objects exposed
to reactive gas as an aspect of case-carburization processing
according to the invention.
[0029] FIG. 5 shows a diagram of an example internal structure of a
processing system that may be used to implement one or more of the
embodiments herein.
[0030] FIG. 6 shows an example embodiment of a method of generating
a user-adjustable thermal processing parameter profile for use by a
sintering furnace.
DETAILED DESCRIPTION OF THE INVENTION
[0031] A description of example embodiments of the invention
follows.
[0032] Described herein are embodiments of a variable metallurgy
property (VMP) system for generating a user-adjustable profile of
thermal processing parameters. The VMP may generate, based on
metallurgical characteristics and other materials properties
provided by the user, a profile for each of one or more thermal
processing parameters. The properties may include, for example,
microstructures and chemistries (e.g., carbon content), among
others described in more detail herein.
[0033] In some embodiments, the VMP system may direct the
processing system to develop a particular outcome with respect to
the resulting process cycle and materials properties, based on a
set of parameters provided by the user. The set of parameters may
be a part or parts to be processed according to a default set of
conditions. The VMP system may permit the user to adjust the
default set of conditions to suit the users requirements, then
direct the processing system to develop a particular outcome with
respect to the resulting process cycle and materials properties,
based on the adjusted default conditions.
[0034] In some embodiments, the VMP system may facilitate an
interactive process setup procedure that guides the user to develop
a particular outcome with respect to the resulting process cycle
and materials properties.
[0035] The VMP system may operate within an additive manufacturing
system 100 as shown in FIG. 1A. Such an example additive
manufacturing system 100 may include a printing subsystem 102, one
or more post-processing subsystems 104 and a furnace subsystem. A
build box subsystem 108 may convey 110 one or more objects being
fabricated through the fabrication process, communicating 112 with
the different subsystems as the object(s) proceed through the
fabrication process. It should be understood that although a build
box subsystem 108, which is relevant to a binder-jet printing
subsystem, is shown in the example system of FIG. 1A, the described
embodiments may be used with other types of printer subsystems. It
should also be understood that at one or more of the
post-processing subsystems 104 and for the furnace subsystem 106,
the object(s) being fabricated may be removed from the build box
subsystem 108 to accomplish the processing associated with those
subsystems. A control subsystem 114 may communicate with each of
the subsystems, providing those subsystems with information
necessary to accomplish the associated processing steps, and to
monitor and control the processing steps.
[0036] The thermal processing parameter profiles described herein
may define a particular parameter characteristic with respect to
another variable, such as time, furnace temperature, atmosphere
characteristics, or other relevant variables.
[0037] FIG. 1B illustrates an example embodiment of a VMP system
120 configured to operate within an additive manufacturing system
100. Although the additive manufacturing comprises the subsystems
shown in FIG. 1A, only a subset of the subsystems is shown in FIG.
1B.
[0038] A user interface 122 may receive materials properties 206
from the user, and provide the materials properties 124 to the VMP
system 120 in a format suitable for the VMP system 120. In other
embodiments, the user interface 122 may convey the materials
properties 124 to the control system 110, and the control system
provides the formatted materials properties to the VMP system
120.
[0039] The VMP system 120 may communicate with the furnace
subsystem 106 to ascertain one or more thermal processes 126
associated with the furnace 106. The VMP system 120 may identify
one or more object characteristics 210 associated with an object
130. The object characteristic(s) 128 may be provided to the VMP
system 120 by the control system 110. In other embodiments, the
object characteristic(s) 128 may be provided from another source,
for example through the user interface 122 or from the build box
subsystem 108 from which the object originated.
[0040] The VMP system 120 may determine a thermal processing
parameter profile 132 corresponding to each of the thermal
processes 126, based on the one or more object characteristics 128
and the one or more materials properties 124. The VMP system 120
may provide the thermal processing parameter profile 132 to the
furnace subsystem 106.
[0041] FIGS. 1C and 1D illustrate an example process workflow
according to the invention. FIG. 1C depicts the processing job
setup workflow, and FIG. 1D depicts the job execution workflow.
[0042] FIG. 1C, which depicts the job execution workflow, begins
with the user determining which part or parts 140 are to be
fabricated. The user, employing VMP system-associated software
running on a computing device 142 (e.g., general purpose desktop or
laptop computer or workstation) carries out the job setup
procedure. Through a graphical user interface (GUI) 144
instantiated on the computing device 142, the user selects one or
more appropriate part IDs corresponding to the part(s) 140. The
user further selects the furnace type and other furnace parameters
through the GUI 144, and any other parameters associated with the
part(s) processing cycle.
[0043] The VMP system evaluates 146 the part(s) with respect to the
selected furnace characteristics and the other characteristics
provided by the user. The VMP system may evaluate, for example, the
total part(s) mass for the job based on part-related information
stored in a database associated with the VMP system, to determine
certain processing parameters required and whether or not the
furnace is capable of performing the desired processing cycle. As
part of this evaluation, the VMP system may request additional
information from the user, either through data entry fields or
through a menu of suggested choices.
[0044] Once the VMP system has generated a processing profile, the
VMP system presents 148 a job summary 150 to the user through the
GUI 144 of the computing device 142 or other presentation facility
associated with the VMP system. The VMP system may provide the user
with an opportunity to modify and/or approve the processing job.
Once the user is satisfied with the job summary, the VMP system may
store 152 the corresponding job processing profile in a database or
other storage system that is available to the furnace
subsystems.
[0045] FIG. 1D, which depicts the job execution workflow, begins
with the user selecting 160, at the furnace subsystem 162, a
processing job 164 that was created in the procedure of FIG. 1C.
Once a processing job 164 is selected, the furnace subsystem 162
may evaluate 166 the processing profile associated with the
processing job 164 to determine if appropriate gas species, gas
volumes, and other resources are available. For example, the
furnace subsystem 162 may determine if tanks containing gas species
appropriate for the processing job 164 are connected to the furnace
subsystem 162. If such tanks are not connected, the furnace
subsystem 162 may prompt the user to acquire and connect
appropriate resources.
[0046] As another example, the furnace subsystem 162 may determine
if enough of the required gas species is available to complete the
processing job 164. If sufficient quantities of the gas are not
available, the furnace subsystem 162 may prompt the user to ensure
that sufficient quantities of the gas species are available. For
example, the furnace subsystem 162 may inform the user that the
user must hot-swap gas reservoirs before the gas runs out,
otherwise the furnace will go into "hold" at 200.degree. below peak
temperature. The furnace subsystem may 162 inform the user that a
countdown will be presented during which the hot-swap must be
performed, otherwise the furnace subsystem 162 may end the
processing job. Once such notifications have been presented, the
furnace subsystem 162 may prompt the user for an instruction to
proceed.
[0047] The user may then start 168 the processing job 164 at the
furnace subsystem 162. The furnace subsystem 162 may then begin
executing the processing job, while providing the user with
processing status information 170 so that the user may monitor 172
the job status. The processing status information 170 may be a
graphically-based function of time, as shown in FIG. 1D, or it may
be textual readout in tabular or other suitable form, or
combinations thereof, or other known techniques for presenting such
processing status information.
[0048] In an example embodiment, an object may be printed from 4140
alloy nominal feedstock steel, using a printing subsystem of an
additive manufacturing system. The user of the additive
manufacturing system may select, for example, a particular
(alloying) element content (e.g., carbon content) of the
constituent 4140 alloy steel to be present in the steel after
thermal processing. The VMP system may evaluate the desired carbon
content input from the user and generates therefrom one or more
thermal processing parameter profiles to produce a desired
carburization/decarburization effect, and provides the thermal
processing parameter profile(s) to the thermal processing furnace
subsystem. In one example embodiment, a thermal processing
parameter profile may comprise controlling one or more of (i) the
gas flow rate, (ii) gas species and (iii) chamber pressure, within
the furnace subsystem. As used herein, the "chamber pressure"
refers to the internal atmosphere pressure within the processing
chamber of the furnace subsystem.
[0049] The specific carbon content control technique to be
manipulated by the VMP system may depend on the type of furnace
being employed. For example, in a graphite chamber with insulation,
the VMP system may control carbon content by varying one or more of
gas flow rate, chamber pressure, and furnace load. For a tube
furnace, in the absence of a carbon source, the VMP system may
control carbon content of the part being processed by varying a
methane (CH.sub.4) gas flow upon cooling.
[0050] Adjusting the carbon content of the 4140 alloy steel may
produce a very wide range of ductility and/or hardness to the user
for alloy steels. In one embodiment, the user may provide ductility
and/or hardness as a desired property, the VMP system determines
the required carbon content to achieve the desired ductility and/or
hardness, and the VMP system produces a thermal processing
parameter profile to the furnace subsystem that produces the
determined carbon content of the printed object(s).
[0051] The carbon content of the printed object can be altered by
furnace load (i.e., the total mass and/or cross-sectional thickness
of parts placed in the furnace) as well as gas flow rate, chamber
pressure and/or gas species to allow a predefined carbon potential
atmosphere to be maintained in the workspace. A carbon potential
probe would interface with the software to adjust gas flows and
other process parameters to maintain the desired carbon potential.
This is due to the effect of binder amount on carburizing potential
of thermal process. Furnace load and gas flow rate, chamber
pressure and/or gas species are thus example thermal processing
parameters that the VMP system may determine and provide to the
furnace subsystem to adjust the final microstructure, while keeping
all the other profiles of furnace parameters (e.g., temperature,
time, etc.) constant.
[0052] In an alternative embodiment, the carbon potential may be
controlled by storing carbon-containing binder products (e.g.,
products (hydrocarbons) resulting from thermal de-binding), such
that the binder products can be released later in the sinter cycle
to add carbon potential to the local atmosphere. The binder
hydrocarbon products may be stored in a binder trap associated with
the sintering furnace. A valve that controls a path from the binder
trap to the sintering furnace may be opened to expose the
de-binding products to the sintering furnace atmosphere. In some
embodiments, the de-binding products may be heated to encourage the
contribution of the de-binding product to the carbon potential of
the sintering furnace atmosphere.
[0053] This use of the de-binding product may allow an increase of
the carbon potential without relying solely on the introduction of
a carburizing process gas. Further, desired carbon potentials may
not be achievable with an explosion-proof methane mixture of
process gas, so de-binding product may be used in conjunction with
such a methane mixture of process gas (or other such
explosion-proof mixtures) to boost the carbon potential to required
levels.
[0054] For the production of certain high carbon tool steels, there
is a trade-off between densification and carbon content, such that
the process cannot achieve both high densification and high carbon
content with a given set of parameters. In one embodiment, a part
may be densified first, at the expense of decarburizing the part,
and then the de-binding hydrocarbon products may be used as a
carburizing agent in a post-sintering carburizing heat
treatment.
[0055] In an example embodiment, the VMP system may provide furnace
load recommendations to the furnace user, so that the user can
manually adjust the furnace load. In other embodiments, the furnace
subsystem may automatically adjust the furnace load based on a
furnace load parameter profile communicated to it by the VMP
system.
[0056] In an example embodiment, the user may select (e.g.,
thorough a user interface to the system) particular parts to be
processed, and the VMP system may determine the total mass and/or
cross-sectional thickness of objects to be sintered in in a
particular thermal processing run, based on the user selections,
along with specified material properties and/or desired
microstructure. The VMP system may then determine, based on the
entered total mass and/or cross-sectional thickness of the objects
and desired microstructure for a particular production run, the gas
flow rate, chamber pressure and/or gas species needed to achieve
that microstructure in that particular production additive
manufacturing run.
[0057] In some embodiments, the user interface may, in addition to
a selection of one or more particular parts, as described above,
comprise one or more advanced menu selections for providing
additional levels of detail to the metallurgical processing. One
example menu is presented below. In an embodiment, a user may
access this example menu by selecting an "ADVANCED 1" button image
on the user interface, although other selection facilities may be
used: [0058] 1--fine pearlite+ferrite [0059] 2--coarse
pearlite+ferrite [0060] 3--full bainite [0061] 4--bainite+ferrite
[0062] 5--bainite+pearlite+ferrite [0063] 6--martensite [0064]
6--martensite+pearlite
[0065] The user may select a subsequent menu, as presented in the
example below, which provides the user with selections of
additional processing parameters: [0066] 1--Hardness [0067] 2--Case
hardened [0068] 3--Ductility [0069] 4--TRS (Transverse Rupture
Strength)
[0070] Selection of one of the above-referenced subsequent menu
items may prompt the user for additional information. For example,
if the user selects 1, hardness, the user may be presented with a
coarse set of choices, e.g., "hard," "medium," and "soft."
Alternatively, the user may be presented with a range of symbols
(e.g., numbers), where one end of the range is designated as
"hardest" and the other end of the range is designated as
"softest." In some embodiments, the user may be presented with an
input field, and prompted to enter a number within a hardness
range.
[0071] As another example, if the user selects "2--Case hardened"
from the subsequent menu, the user may be presented with a "yes/no"
choice. If the user selects "yes," the user may be presented with
the following example choices for submitting additional
information: [0072] 1--Case depth [0073] 2--Case hardness [0074]
3--Core hardness
[0075] In some embodiments, the VMP system may accept a transverse
rupture strength (TRS) input from the user.
[0076] FIG. 2A illustrates an example user interface that depicts a
materials selection menu. For this example, the 4140 materials all
have the same material content, whether it is Bainite,
Pearlite-Ferrite, or Ferrite; the final materials all depend on the
treatment within the furnace subsystem. Further, the resulting
microstructures are dependent on the cooling control within the
furnace subassembly (i.e., how quickly the object is cooled).
[0077] In other embodiments, the user interface may comprise one or
more various graphical user interface (GUI) controls known in the
art that may facilitate a user's selection of a part (or parts) and
the user's input of materials properties. For example, the user
interface may comprise a GUI showing one or more slide controls
that each traverses a range of a materials property (e.g., a range
of carbon content) such that the user manipulates the slide control
to select a particular materials property value. The VMP system
modifies the fabrication recipe to produce the selected result.
[0078] As another example, the GUI may show a two-dimensional space
defined by a pair of orthogonal axes (i.e., an X axis and a Y
axis), each axis representing a range of a material property. The
user identifies two parameters (e.g., a first key characteristic
and a second key characteristic) by selecting a point within the
area, and the VMP system modifies the fabrication recipe to produce
a result that corresponds to the selected parameters.
Alternatively, the GUI may provide for user entry of parameters
through a three-dimensional space defined by three orthogonal axes,
or a set of two or more such two or three dimensional spaces.
[0079] The VMP system may produce process parameter profiles as a
function of the input materials properties, based on a fixed
mapping. In such cases, the VMP system may employ a look-up table
(LUT), implemented in local memory, to accomplish the mapping. The
contents of the LUT may be generated empirically, based on part
analysis feedback data from test process runs or actual production
process runs. The contents of the LUT may alternatively be
generated analytically according to formulae based on established
materials theory.
[0080] Alternatively, the VMP system may produce the process
parameter profiles analytically, in real-time or near real-time, by
a processor executing instruction code that evaluates the input
materials properties according to formulae based on established
materials theory. In some embodiments, the VMP system may produce
the thermal processing parameter profiles according to a
combination of LUT implementation and real-time/near real time
analytical processing.
[0081] The VMP system may include a "Super User Mode," which allows
a user to tailor a process parameter profile according to specific
result requirements. The VMP system may evaluate the tailored
parameter profile to determine if the resulting parameter
combination represents an impossible scenario or represents a
parameter combination that could pose a hardware failure, a failure
of the material being processed, or both.
[0082] The VMP system may unconditionally preclude certain such
tailored parameter profiles, for example when the associated
parameters would lead to an impossible scenario or hardware
failure. The VMP may notify the user that the precluded parameter
profile will not be run, and may provide the user with reasons
and/or justification for the preclusion.
[0083] In some cases, for example when the tailored parameter
profile may lead to material failure, the VMP system may
conditionally preclude the profile. In such cases, the user may be
notified of the conditional preclusion, and may be given an
override option. The VMP system may also provide the user with a
rationale for the conditional preclusion, with which the user may
use to guide a potential override decision.
[0084] Other process parameters (or parameter profiles) may
additionally (or alternatively) be provided in a profile to the
furnace subsystem. For example, the oxygen content in the gas flow
may be varied for processing titanium-based alloys to provide
variations in hardness vs. ductility of the object material. In
this case, the PaO.sub.2 (equilibrium oxygen partial pressure) is
monitored by the VMP system rather than carbon potential. The VMP
system may receive processing data from sensors associated with the
furnace (e.g., carbon potential probe, or oxygen probe), to monitor
processing conditions during the processing run with respect to the
active parameter profile.
[0085] An example VMP system may provide thermal processing
parameter profiles to produce hardening oxide and/or nitride layers
on a material such as titanium or aluminum. Anodized aluminum is
just a thick layer of aluminum oxide or aluminum nitride. For
example, the VMP system may facilitate a carbo-nitride processing
of a part or parts by formulating a process to add a specific gas
(e.g., CH.sub.4+NH.sub.3) applied to the part(s) at an ideal
temperature.
[0086] The internal structure of the sintering furnace may comprise
one of several different types, or combinations thereof. For
example, the sintering furnace internal structure may comprise (i)
graphite retort, (ii) carbon retort, (iii) refractory metal retort,
or (iv) ceramic retort, among others, or combinations thereof. The
use of a carbon, refractory metal or ceramic retort may be used for
processing reactive metals such as aluminum and titanium, which
cannot be processed in a graphite retort in addition to tightly
controlling oxygen in the sintering environment. Nesting a
refractory metal or ceramic retort into the graphite retort makes
it possible to process reactive metals in the same furnace
equipment that would otherwise be used for processing non-reactive
metals.
[0087] An example VMP system may provide thermal processing
parameter profiles to the thermal processing furnace subsystem that
define a particular cool-down rate. For example, one cool down rate
may be defined for banite, and a slower cool down rate may be
defined for ferrite+pearlite. A user would thus provide materials
properties input of either "banite" or "ferrite+pearlite" using an
input technique described herein, and the VMP system would generate
process parameter profiles to the furnace that specify the
appropriate cool down rate.
[0088] The VMP system may present a continuous cooling
transformation (CCT) diagram to the user, depicting various
transformation products for different cooling rates. In one
embodiment, the CCT diagram may depict a cooling curve and
resulting transformation products for parameters input by the user.
In another embodiment, user may select a particular cooling rate
curve on the CCT diagram, through the GUI, in order to specify a
desired product result. FIG. 2B shows an example CCT diagram that
the VMP system may present to the user. In FIG. 2B, "F" denotes
ferrite, "P" denotes pearlite, "B" denotes Bainite, and "M" denotes
martensite. The "s" subscript denotes start temperature and the "f"
subscript denotes final temperature.
[0089] An example VMP system may provide thermal processing
parameter profiles to the thermal processing furnace subsystem that
adjust thermal processing parameters such as the internal furnace
atmosphere, vacuum level and the furnace loading, to selectively
harden/carburize the parts. Certain parts may only require a
selected region to be hardened (e.g., the teeth of a gear), but
require other regions of the part maintain ductility (e.g., thin
sections that are prone to embrittlement when too hard/carburized).
Embodiments of the print subsystem may print a thin barrier layer
(also referred to as a stop-off layer) on selected surfaces to
prevent carburization of those selected surfaces, resulting in
selective carburizing.
[0090] For some embodiments, the dominating factor in final carbon
content may be incomplete de-binding. In such an embodiment, the
sections under the thin stop-off may pick up carbon due to
prolonged exposure to carbon from the binder and become harder
selectively. Thus selectively distributing the stop-off may
facilitate the thermal processing of functionally gradient steel.
Similar techniques of distributing stop-off material may
alternatively be used for oxygen hardening of titanium to
facilitate the thermal processing of functionally gradient
titanium. Similar techniques may apply to other processes, for
example for processing titanium with oxygen hardening.
[0091] Since certain final material properties may be dependent on
how the material is exposed to gas flow during processing, the VMP
system may determine gas deflection characteristics needed to
produce a particular metallurgical outcome regarding properties of
the material. Accordingly, the VMP system may direct certain gas
channeling structures to be printed on the part, in the vicinity of
the part, or both. FIGS. 3A and 3B illustrate examples of two such
channeling architectures.
[0092] FIG. 3A illustrates a focusing structure 302, which collects
a gas flow 304 and channels the gas flow 304 into a focused gas
flow 306, directed to a particular region 308 of part 310 being
processed.
[0093] FIG. 3B illustrates a deflection structure 320, which
deflects and channels a gas flow 322 into a deflected gas flow 324,
directed around a part 326 being processed.
[0094] FIGS. 3A and 3B are intended to provide examples types of
gas flow channeling that may be used to control material properties
during processing, and are not intended to be limiting. Other such
channeling structures may be used alternatively or in addition to
those described in FIGS. 3A and 3B.
[0095] Software controlled vacuum levels, at specific thermal
zones, may be used to produce a controlled surface enrichment of
liquid phase-based materials, for example tungsten carbide and
cobalt (WC+Co), tungsten carbide and nickel (WC+Ni), and titanium
carbide and Nickel (TiC+Ni). Such a software-controlled process may
facilitate enhanced secondary operations such as brazing, or
application of surface coatings to the base matrix.
[0096] Printed objects, after thermal processing and while cooling,
can be exposed to reactive gas species which can be supplied
through a hot-swap gas cylinders. For example, these reactive
gasses can provide a case-carburization which will yield a carbon
content gradient from part surface to center. Two example objects
402, 404, which have been so exposed to reactive gas, are shown in
FIG. 4A. If the example objects 402, 404 are cross-sectioned, as
shown in FIGS. 4B and 4C, the inner core will be still soft,
ductile with high toughness. The outer layer is known as the case,
which gives a harder and wear resistant surface. The processing can
be such that the outer surface has a high corrosion resistance. The
depth of this case-carburized layer or carbonstricted layer can be
made to vary and may be controlled by a software based processing
system or other control technique. FIG. 4C illustrates carbon
percentage (bottom trace and left side of graph) and hardness (top
trace and right side of graph) across the cross-sectional view. As
can be seen, the carbon percentage and hardness decrease from the
outer portion of the object toward the core portion of the
object.
[0097] An object may be "decarburized" by implementing the
carburization process described above in reverse. Decarburizing an
object requires exposing the object to reactive gases such as
oxygen or hydrogen. The reactive gases combine with carbon in the
object, primarily at the surface of the object to result in a
reverse carbon gradient (i.e., carbon content increases with
distance from the object surface into the object core.
[0098] In some embodiments, decarburizing may be accomplished by
changing the H.sub.2/H.sub.2O ratio in the surface atmosphere. The
H.sub.2/H.sub.2O ratio may be reduced by introducing moisture into
the sintering atmosphere (by, for example, spraying water), which
will make the sintering atmosphere suitable for decarburizing.
Similarly, carburizing, boriding or nitriding gases can be
introduced into the sintering atmosphere at critical temperatures
to modify the chemistry, or surface chemistry, of the part.
[0099] An embodiment may facilitate a user adding surface
modifications for parts up-front, either at the setup procedure as
described with respect to example embodiment of FIG. 1C, or prior
to starting the job as described with respect to the example
embodiment of FIG. 1D. Embodiments may require that the first part
having a surface modification implemented defines the processing
cycle, such that subsequent parts modified (either surface
modifications or non-surface modifications) will be conditional on
the first part's processing profile. In other words, if a part
modification subsequent to the first part modification would
conflict with the first part modification, the VMP system may
notify the user of the conflict and may preclude such subsequent
modifications, so as to prevent the fabrication of defective parts
in a scenario that requires multiple parts nested in a build
box.
[0100] Embodiments of the VMP system may facilitate certain
ancillary processing procedures being accomplished during the
primary thermal processing cycle. For example, the VMP system may
facilitate one or more of annealing, aging, tempering,
stress-relieving and spheroidizing (a heat treatment for iron-based
alloys to convert the alloys into ductile and machinable alloys) of
a part or parts being processed within the additive manufacturing
system. This step requires an additional type of austenitizing
furnace and a water or oil quenching step after sintering is
completed, and before these heat treatments can be done in the
sintering furnace. After the sintering cycle is over and the part
is completely solid, the part may be austenitized and quenched
using another type of furnace and quenching equipment. After
austenitizing and quenching is done, the solid part can be put back
in the furnace for one or more of the software-programmed heat
treatments that are listed above. The type, temperature and the
duration of these heat treatments (annealing, aging, tempering,
etc.) may be pre-programmed in the software using an algorithm that
is a function of at least one of (a) the material, (b) required
final hardness/toughness and (c) the thickest section of the
part.
[0101] FIG. 5 is a diagram of an example internal structure of a
processing system 500 that may be used to implement one or more of
the embodiments herein. Each processing system 500 contains a
system bus 502, where a bus is a set of hardware lines used for
data transfer among the components of a computer or processing
system. The system bus 502 is essentially a shared conduit that
connects different components of a processing system (e.g.,
processor, disk storage, memory, input/output ports, network ports,
etc.) that enables the transfer of information between the
components.
[0102] Attached to the system bus 502 is a user I/O device
interface 504 for connecting various input and output devices
(e.g., keyboard, mouse, displays, printers, speakers, etc.) to the
processing system 500. A network interface 506 allows the computer
to connect to various other devices attached to a network 508.
Memory 510 provides volatile and non-volatile storage for
information such as computer software instructions used to
implement one or more of the embodiments of the present invention
described herein, for data generated internally and for data
received from sources external to the processing system 500.
[0103] A central processor unit 512 is also attached to the system
bus 502 and provides for the execution of computer instructions
stored in memory 510. The system may also include support
electronics/logic 514, and a communications interface 516. The
communications interface 516 may comprise the interface to the user
interface 204, the interface to the furnace subsystem 106, or the
interface to the control subsystem 110, as described with reference
to FIG. 2A.
[0104] In one embodiment, the information stored in memory 510 may
comprise a computer program product, such that the memory 510 may
comprise a non-transitory computer-readable medium (e.g., a
removable storage medium such as one or more DVD-ROM's, CD-ROM's,
diskettes, tapes, etc.) that provides at least a portion of the
software instructions for the invention system. The computer
program product can be installed by any suitable software
installation procedure, as is well known in the art. In another
embodiment, at least a portion of the software instructions may
also be downloaded over a cable communication and/or wireless
connection.
[0105] One example embodiment of a method of generating a
user-adjustable thermal processing parameter profile for use by a
sintering furnace is shown in FIG. 6. The method may comprise
receiving 602, through a user interface, one or more materials
properties provided by a user. The method may further comprise
communicating 604 with a furnace to ascertain one or more thermal
processes associated with the furnace, and identifying 606 one or
more part characteristics associated with a part to be processed by
furnace. The process may further comprise determining 608 a thermal
processing parameter profile of at least one thermal processing
parameter corresponding to each of the thermal processes, based on
(i) the one or more part characteristics and (ii) the one or more
materials properties, the thermal processing parameter profile
characterizing a cycle of the one or more thermal processes.
[0106] It will be apparent that one or more embodiments described
herein may be implemented in many different forms of software and
hardware. Software code and/or specialized hardware used to
implement embodiments described herein is not limiting of the
embodiments of the invention described herein. Thus, the operation
and behavior of embodiments are described without reference to
specific software code and/or specialized hardware--it being
understood that one would be able to design software and/or
hardware to implement the embodiments based on the description
herein.
[0107] Further, certain embodiments of the example embodiments
described herein may be implemented as logic that performs one or
more functions. This logic may be hardware-based, software-based,
or a combination of hardware-based and software-based. Some or all
of the logic may be stored on one or more tangible, non-transitory,
computer-readable storage media and may include computer-executable
instructions that may be executed by a controller or processor. The
computer-executable instructions may include instructions that
implement one or more embodiments of the invention. The tangible,
non-transitory, computer-readable storage media may be volatile or
non-volatile and may include, for example, flash memories, dynamic
memories, removable disks, and non-removable disks.
[0108] While this invention has been particularly shown and
described with references to example embodiments thereof, it will
be understood by those skilled in the art that various changes in
form and details may be made therein without departing from the
scope of the invention encompassed by the appended claims.
* * * * *