U.S. patent application number 15/449575 was filed with the patent office on 2017-09-07 for tuning pneumatic jetting of metal for additive manufacturing.
The applicant listed for this patent is Desktop Metal, Inc.. Invention is credited to Paul A. Hoisington, Kevin Michael Li, Jonah Samuel Myerberg, Toshana Krishna Natchurivalapil Rappai James, Emanuel Michael Sachs.
Application Number | 20170252809 15/449575 |
Document ID | / |
Family ID | 59722580 |
Filed Date | 2017-09-07 |
United States Patent
Application |
20170252809 |
Kind Code |
A1 |
Myerberg; Jonah Samuel ; et
al. |
September 7, 2017 |
TUNING PNEUMATIC JETTING OF METAL FOR ADDITIVE MANUFACTURING
Abstract
Devices, systems, and methods are directed to adjusting a
pneumatic circuit associated with pneumatic ejection of liquid
metal from a nozzle as the nozzle moves along a controlled
three-dimensional pattern to fabricate a three-dimensional object.
The adjustment of the pneumatic circuit can facilitate adjusting a
pressure profile within the nozzle as pressurized gas moves through
the nozzle to eject, through pneumatic force, liquid metal from the
nozzle. Through adjustment of the pneumatic circuit,
characteristics of the liquid metal (e.g., size, shape, and flow
rate) can be controlled to facilitate control over fabrication of
the three-dimensional object.
Inventors: |
Myerberg; Jonah Samuel;
(Lexington, MA) ; Natchurivalapil Rappai James; Toshana
Krishna; (Somerville, MA) ; Sachs; Emanuel
Michael; (Newton, MA) ; Hoisington; Paul A.;
(Hanover, NH) ; Li; Kevin Michael; (Brighton,
MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Desktop Metal, Inc. |
Burlington |
MA |
US |
|
|
Family ID: |
59722580 |
Appl. No.: |
15/449575 |
Filed: |
March 3, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62303324 |
Mar 3, 2016 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B33Y 50/02 20141201;
B22F 3/1055 20130101; B33Y 30/00 20141201; B22F 3/008 20130101;
B33Y 10/00 20141201; B22F 2999/00 20130101; B22F 3/115 20130101;
B22F 2999/00 20130101; B22F 3/008 20130101; B22F 3/003 20130101;
B22F 2009/0892 20130101; B22F 2202/05 20130101; B22F 2203/13
20130101; B22F 2999/00 20130101; B22F 3/008 20130101; B22F 3/115
20130101; B22F 2999/00 20130101; B22F 3/008 20130101; B22F 3/1115
20130101 |
International
Class: |
B22F 3/115 20060101
B22F003/115; B33Y 50/02 20060101 B33Y050/02; B33Y 30/00 20060101
B33Y030/00; B22F 3/00 20060101 B22F003/00; B33Y 10/00 20060101
B33Y010/00 |
Claims
1. An additive manufacturing system, the system comprising: a
nozzle defining a volume and a discharge orifice in fluid
communication with one another, the nozzle including an exhaust
passage in fluid communication with the volume; a source of a
pressurized gas in selective fluid communication with the volume of
the nozzle; and a media supply in fluid communication with the
volume of the nozzle such that metal from the media supply is
movable into the volume, wherein the exhaust passage has an
adjustable back pressure to control a pressure profile in the
volume of the nozzle as the pressurized gas moves through the
volume to eject a liquid form of the metal from the discharge
orifice along a controlled three-dimensional pattern for
fabrication of a three-dimensional object.
2. The system of claim 1, wherein the exhaust passage includes a
hydraulic inductance, the hydraulic inductance having a dissipating
resistance to flow in response to force exerted, over a period of
time, on the hydraulic inductance by venting pressurized gas in the
exhaust passage.
3. The system of claim 2, wherein the hydraulic inductance includes
a paddle wheel rotatable in response to force exerted on the paddle
wheel by venting pressurized gas in the exhaust passage.
4. The system of claim 2, a paddle wheel rotatable in response to
force exerted on the paddle wheel by venting pressurized gas in the
exhaust passage.
5. The system of claim 2, wherein a time-varying profile of the
resistance of the hydraulic inductance is adjustable.
6. The system of claim 1, wherein the exhaust passage includes a
variable hydraulic resistance.
7. The system of claim 6, wherein the variable hydraulic resistance
includes a variable length of the exhaust passage.
8. The system of claim 6, wherein the variable hydraulic resistance
includes a flow restriction having a variable size.
9. The system of claim 1, further comprising a valve in fluid
communication with the source of the pressurized gas and the
volume, the valve actuatable to deliver pulses of the pressurized
gas to the volume.
10. A method of additive manufacturing, the method comprising:
directing a metal into a volume defined by a nozzle, the volume in
fluid communication with an exhaust passage defined by the nozzle;
moving a discharge orifice and a build plate relative to one
another along a controlled three-dimensional pattern, the discharge
orifice defined by the nozzle and in fluid communication with the
volume; delivering pulses of pressurized gas into the volume of the
nozzle; and adjusting a back pressure of the exhaust passage
through which the pressurized gas is vented from the volume of the
nozzle, wherein, in response to the adjustment of the back
pressure, the pressurized gas in the volume exerts a force on a
liquid form of the metal in the nozzle to eject the liquid metal
from the discharge orifice as the discharge orifice and the build
plate are moved relative to one another along the controlled
three-dimensional pattern to form a three-dimensional object on the
build plate.
11. The method of claim 10, wherein adjusting the back pressure of
the exhaust passage includes venting the pressurized gas through a
hydraulic inductance having a dissipating resistance to flow in
response to force exerted, over a period of time, on the hydraulic
inductance by the venting pressurized gas in the exhaust
passage.
12. The method of claim 11, wherein the dissipating resistance
dissipates to a substantially constant hydraulic resistance over
the period of time.
13. The method of claim 12, wherein the period of time is less than
a period of the pulses of pressurized gas delivered into the volume
of the nozzle.
14. The method of claim 11, wherein the hydraulic inductance
includes a paddle wheel rotatable in response to force exerted on
the paddle wheel by the venting pressurized gas in the exhaust
passage.
15. The method of claim 10, wherein adjusting the back pressure of
the exhaust passage includes venting the pressurized gas through a
variable hydraulic resistance and adjusting the variable hydraulic
resistance based at least in part on a position of the discharge
orifice with respect to the controlled three-dimensional
pattern.
16. The method of claim 15, wherein the variable hydraulic
resistance includes a flow restriction having a variable size and
varying the variable hydraulic resistance includes changing the
size of the flow restriction.
17. The method of claim 15, wherein the variable hydraulic
resistance includes a variable length of the exhaust passage and
varying the variable hydraulic resistance includes changing the
length of the exhaust passage.
18. The method of claim 10, wherein adjusting the back pressure of
the exhaust passage is based on a volume of the liquid form of the
metal in the volume of the nozzle.
19. The method of claim 10, wherein the exhaust passage is vented
to at least one of atmospheric pressure and a vacuum.
20. The method of claim 19, the metal is directed into the volume
through the exhaust passage.
21. The method of claim 10, further comprising tuning the pulses of
pressurized gas in a multiple of a natural harmonic of the volume
of the nozzle.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit under 35 .sctn.119(e) of
U.S. Prov. App. No. 62/303,324, filed on Mar. 3, 2016, the entire
contents of which are hereby incorporated herein by reference.
FIELD
[0002] The devices, systems, and methods described herein relate to
additive manufacturing, and more specifically to a pneumatic drive
system for additive manufacturing with metallic materials.
BACKGROUND
[0003] Pneumatic jetting can be used to drive droplets of metal
with pressurized air or gas. Such droplets can be accumulated to
form an object. While pneumatic jetting can impart forces to liquid
metal to form a metallic object, considerations related to speed,
accuracy, control, and material properties present challenges for
the use of pneumatic forces for object formation on a large scale.
Accordingly, there remains a need for commercially viable
techniques for additive manufacturing of metal using pneumatic
forces.
SUMMARY
[0004] Devices, systems, and methods are directed to the pneumatic
ejection of liquid metal from a nozzle moving along a controlled
three-dimensional pattern to fabricate a three-dimensional object
through additive manufacturing. The metal is movable into the
nozzle as a valve is actuated to control movement of pressurized
gas into the nozzle. Such movement of metal into the valve as
pressurized gas is being moved into the nozzle to create an
ejection force on liquid metal in the nozzle can reduce or
eliminate the need to replenish a supply of the metal in the nozzle
and, therefore can facilitate continuous or substantially
continuous liquid metal ejection for the fabrication of parts.
[0005] An additive manufacturing system may include a nozzle
defining a volume and a discharge orifice in fluid communication
with one another, a source of a pressurized gas, a valve actuatable
to control fluid communication between the source of pressurized
gas and the volume of the nozzle, and a media supply in fluid
communication with the volume of the nozzle. Metal from the media
supply may be movable into the volume of the nozzle as the valve is
actuated to eject, under pneumatic force of the pressurized gas in
the nozzle, a liquid form of the metal from the discharge orifice
along a controlled three-dimensional pattern associated with
fabrication of a three-dimensional object.
[0006] Implementations may include one or more of the following
features. Metal from the media supply may be movable into the
volume while the valve is positioned to interrupt fluid
communication between the discharge orifice of the nozzle and the
source of the pressurized gas. The nozzle may further define a
first port and a second port, the first port and the second port
spaced apart from one another along the volume of the nozzle, the
actuation of the valve controlling movement of the pressurized gas
into the volume of the nozzle through the first port. The first
port and the second port may be substantially axially aligned with
one another along the volume of the nozzle. The media supply may be
in fluid communication with the volume of the nozzle through the
second port. The second port may be vented to the atmosphere. The
second port may be vented to a vacuum. The system may further
include a media drain in fluid communication with the volume of the
nozzle, where the metal from the media supply is movable from the
volume of the nozzle to the media drain. The discharge orifice and
the first port may be positioned relative to one another such that
metal moving from the media supply to the media drain moves between
the discharge orifice and the first port. The system may further
include a heater arranged to heat at least a portion of the nozzle
adjacent to the discharge orifice. The heater may be one or more of
a resistance heater and an induction heater. The metal supply may
be movable into a portion of the volume adjacent to the discharge
orifice. The system may further include an inert gas curtain
disposed at least partially around the discharge orifice.
[0007] A method of additive manufacturing may include directing a
metal into a volume defined by a nozzle, and moving a discharge
orifice and a build plate relative to one another along a
controlled three-dimensional pattern, where the discharge orifice
is defined by the nozzle and in fluid communication with the
volume. The method may also include, based at least in part on a
position of the discharge orifice along the controlled
three-dimensional pattern, selectively delivering pulses of
pressurized gas into the volume to eject a liquid form of the metal
from the discharge orifice to form a three-dimensional object on
the build plate, where the metal is directed into the volume
defined by the nozzle as the pulses of pressurized gas are
selectively delivered into the volume.
[0008] Implementations may include one or more of the following
features. Selectively delivering pulses of pressurized gas into the
volume to eject the liquid form of the metal may include ejecting
the liquid form of the metal from the discharge orifice in a
direction having a vertical component opposite a direction of
gravity. The method may further include heating the nozzle at least
along a portion of the nozzle defining the discharge orifice.
Directing the metal into the volume defined by the nozzle may
include directing a solid form of the metal into the nozzle. The
method may further include venting the pressurized gas from the
volume of the nozzle through a port defined by the nozzle and in
fluid communication with the atmosphere or a vacuum. Directing the
metal into the volume may include moving the metal into the volume
through the port. The pressurized gas may be inert with respect to
the metal. The method may further include draining the liquid metal
from the volume of the nozzle as the pulses of pressurized gas are
selectively delivered into the volume. The liquid form of the metal
may be ejected into one or more of an inert atmosphere and a vacuum
housed within a build chamber during fabrication of the
three-dimensional object. The method may further include adjusting
the discharge orifice to control a meniscus of the liquid form of
the metal at the discharge orifice.
[0009] Devices, systems, and methods are directed to adjusting a
pneumatic circuit associated with pneumatic ejection of liquid
metal from a nozzle as the nozzle moves along a controlled
three-dimensional pattern to fabricate a three-dimensional object.
The adjustment of the pneumatic circuit can facilitate adjusting a
pressure profile within the nozzle as pressurized gas moves through
the nozzle to eject, through pneumatic force, liquid metal from the
nozzle. Through adjustment of the pneumatic circuit,
characteristics of the liquid metal (e.g., size, shape, and flow
rate) can be controlled to facilitate control over fabrication of
the three-dimensional object.
[0010] An additive manufacturing system may include a nozzle
defining a volume and a discharge orifice in fluid communication
with one another, the nozzle including an exhaust passage in fluid
communication with the volume. The system may also include a source
of a pressurized gas in selective fluid communication with the
volume of the nozzle, and a media supply in fluid communication
with the volume of the nozzle such that metal from the media supply
is movable into the volume, where the exhaust passage has an
adjustable back pressure to control a pressure profile in the
volume of the nozzle as the pressurized gas moves through the
volume to eject a liquid form of the metal from the discharge
orifice along a controlled three-dimensional pattern for
fabrication of a three-dimensional object.
[0011] Implementations may include one or more of the following
features. The exhaust passage may include a hydraulic inductance,
the hydraulic inductance having a dissipating resistance to flow in
response to force exerted, over a period of time, on the hydraulic
inductance by venting pressurized gas in the exhaust passage. The
hydraulic inductance may include a paddle wheel rotatable in
response to force exerted on the paddle wheel by venting
pressurized gas in the exhaust passage. The paddle wheel may be
rotatable in response to force exerted on the paddle wheel by
venting pressurized gas in the exhaust passage. A time-varying
profile of the resistance of the hydraulic inductance may be
adjustable. The exhaust passage may include a variable hydraulic
resistance. The variable hydraulic resistance may include a
variable length of the exhaust passage. The variable hydraulic
resistance may include a flow restriction having a variable size.
The system may further include a valve in fluid communication with
the source of the pressurized gas and the volume, where the valve
is actuatable to deliver pulses of the pressurized gas to the
volume.
[0012] A method of additive manufacturing may include directing a
metal into a volume defined by a nozzle, the volume in fluid
communication with an exhaust passage defined by the nozzle. The
method may also include moving a discharge orifice and a build
plate relative to one another along a controlled three-dimensional
pattern, the discharge orifice defined by the nozzle and in fluid
communication with the volume. The method may also include
delivering pulses of pressurized gas into the volume of the nozzle,
and adjusting a back pressure of the exhaust passage through which
the pressurized gas is vented from the volume of the nozzle, where,
in response to the adjustment of the back pressure, the pressurized
gas in the volume exerts a force on a liquid form of the metal in
the nozzle to eject the liquid metal from the discharge orifice as
the discharge orifice and the build plate are moved relative to one
another along the controlled three-dimensional pattern to form a
three-dimensional object on the build plate.
[0013] Implementations may include one or more of the following
features. Adjusting the back pressure of the exhaust passage may
include venting the pressurized gas through a hydraulic inductance
having a dissipating resistance to flow in response to force
exerted, over a period of time, on the hydraulic inductance by the
venting pressurized gas in the exhaust passage. Dissipating
resistance may dissipate to a substantially constant hydraulic
resistance over the period of time. The period of time may be less
than a period of the pulses of pressurized gas delivered into the
volume of the nozzle. The hydraulic inductance may include a paddle
wheel rotatable in response to force exerted on the paddle wheel by
the venting pressurized gas in the exhaust passage. Adjusting the
back pressure of the exhaust passage may include venting the
pressurized gas through a variable hydraulic resistance and
adjusting the variable hydraulic resistance based at least in part
on a position of the discharge orifice with respect to the
controlled three-dimensional pattern. The variable hydraulic
resistance may include a flow restriction having a variable size
and varying the variable hydraulic resistance may include changing
the size of the flow restriction. The variable hydraulic resistance
may include a variable length of the exhaust passage and varying
the variable hydraulic resistance may include changing the length
of the exhaust passage. Adjusting the back pressure of the exhaust
passage may be based on a volume of the liquid form of the metal in
the volume of the nozzle. The exhaust passage may be vented to at
least one of atmospheric pressure and a vacuum. The metal may be
directed into the volume through the exhaust passage. The method
may also include tuning the pulses of pressurized gas in a multiple
of a natural harmonic of the volume of the nozzle.
[0014] Devices, systems, and methods are directed to separating
sediment from liquid metal ejected, through pneumatic force, from a
nozzle moving along a controlled three-dimensional pattern to
fabricate a three-dimensional object. The separation of the
sediment from the liquid metal can reduce the likelihood that the
nozzle will become clogged or otherwise degraded during fabrication
of the three-dimensional object or over the course of fabrication
of multiple objects. Accordingly, the separation of the sediment
from the liquid metal can facilitate, for example, the use of
pneumatic ejection of liquid metal for high volume production of
parts.
[0015] An additive manufacturing system may include a nozzle
defining a volume, a first port, a second port, and a discharge
orifice in fluid communication with one another. The system may
also include a source of a pressurized gas in selective fluid
communication with the volume of the nozzle through the first port,
a media supply in fluid communication with the volume of the nozzle
through the second port, and one or more baffles disposed in the
volume of the nozzle such that an axis defined by the discharge
orifice and the second port intersects the one or more baffles, the
one or more baffles oriented to direct sediment of a liquid form of
a metal in the volume to a reservoir portion of the volume, the
reservoir portion away from the discharge orifice.
[0016] Implementations may include one or more of the following
features. The one or more baffles may define a non-linear path
between the discharge orifice and the reservoir portion of the
volume. The non-linear path between the discharge orifice and the
reservoir portion of the volume may include an increase in height,
along an axis perpendicular to the discharge orifice, along the
non-linear path from the reservoir portion to the discharge
orifice. The one or more baffles may span a dimension of the
volume. The one or more baffles may include a plurality of baffles
substantially parallel to one another. The one or more baffles may
be angled with respect to an axis perpendicular to the discharge
orifice. The media supply may be configured to move a solid form of
metal into the volume through the second port. The second port may
be vented to atmosphere such that pressurized gas exits the volume
through the second port. A flow of pressurized gas through the
first port may be substantially unimpeded by the one or more
baffles. The system may also include a heater arranged to heat at
least portions of the nozzle defining the discharge orifice and
along which the one or more baffles are disposed. The heater may
include one or more of a resistance heater, an induction heater, a
convection heater, and a radiation heater.
[0017] A method of additive manufacturing may include directing a
metal into a volume defined by a nozzle, and moving a discharge
orifice and a build plate relative to one another along a
controlled three-dimensional pattern, where the discharge orifice
is defined by the nozzle and in fluid communication with the
volume. The method may also include separating, in the volume, a
liquid form of the metal from a sediment. Based at least in part on
a position of the discharge orifice along the controlled
three-dimensional pattern, the method may also include delivering
pressurized gas into the volume to eject the liquid form of the
metal from the discharge orifice to form a three-dimensional object
on the build plate.
[0018] Implementations may include one or more of the following
features. Separating the liquid form of the metal from the sediment
may include moving the liquid form of the metal along a non-linear
path from a sediment reservoir in the volume to the discharge
orifice. Separating the liquid form of the metal from the sediment
may further include increasing, in the volume, a height of the
liquid form of the metal relative to the discharge orifice. The
non-linear path may be at least partially defined by one or more
baffles disposed in the volume. The liquid form of the metal may be
separated from the sediment as the pressurized gas is delivered
into the volume.
[0019] Devices, systems, and methods are directed to switching
between pneumatically actuated ejection and electrically actuated
ejection of liquid metal from a nozzle moving along a controlled
three-dimensional pattern to fabricate a three-dimensional object.
Electrically actuated ejection can be useful, for example, for
delivering discrete droplets in areas of the object requiring a
high degree of accuracy. Pneumatic ejection can be useful, for
example, for delivering a stream of liquid metal from the nozzle to
provide liquid metal rapidly to areas of the object that require
less accuracy (e.g., an inner portion of the object). Accordingly,
switching between pneumatically actuated ejection and electrically
actuated ejection can facilitate accurate and rapid production of
parts through additive manufacturing.
[0020] A method of additive manufacturing may include directing a
metal into a volume defined by a nozzle, and moving a discharge
orifice and a build plate relative to one another along a
controlled three-dimensional pattern, the discharge orifice defined
by the nozzle and in fluid communication with the volume. The
method may also include, based at least in part on a position of
the discharge orifice along the controlled three-dimensional
pattern, selectively switching between pneumatically actuated
ejection and electrically actuated ejection of a liquid form of the
metal from the discharge orifice. The method may also include
ejecting the liquid form of the metal from the discharge orifice
according to the selected one of the pneumatically actuated
ejection and the electrically actuated ejection to form at least a
portion of a three-dimensional object.
[0021] Implementations may include one or more of the following
features. Upon selection of the pneumatically actuated ejection,
ejecting the liquid form of the metal from the discharge orifice
may include ejecting a substantially constant stream of the liquid
form of the metal from the discharge orifice. Upon selection of the
electrically actuated ejection, ejecting the liquid form of the
metal from the discharge orifice may include controlling a pulsed
electrical current. Droplets of the liquid form of the metal may be
ejected from the discharge orifice in response to the pulsed
electrical current. Selectively switching between pneumatically
actuated ejection and electrically actuated ejection may include
selecting the electrically actuated ejection along a border of the
controlled three-dimensional pattern and selecting the
pneumatically actuated ejection along an excursion away from the
border of the controlled three-dimensional pattern. Ejecting liquid
metal from the discharge orifice according to pneumatically
actuated ejection may include delivering pressurized air to the
volume. The method may further include venting the pressurized air
to one or more of the atmosphere and a vacuum as the liquid form of
the metal is ejected through the discharge orifice. Ejecting liquid
metal from the discharge orifice according to the electrically
actuated ejection may include delivering an electric current into
the liquid form of the metal. The electric current may result in a
magnetohydrodynamic force exerted on the liquid form of the metal.
The electric current may result in an electrohydrodynamic force
exerted on the liquid form of the metal. Ejecting liquid metal from
the discharge orifice according to the electrically actuated
ejection may include delivering an electric current to an actuator
in mechanical communication with the liquid form of the metal and
movable in response to the electric current to exert a mechanical
force on the liquid form of the metal to eject the liquid form of
the metal from the discharge orifice. The actuator may include a
piezoelectric element. The method may further include heating the
metal in the volume at least along a portion of the volume defining
the discharge orifice. Directing the metal into the volume may
include moving the metal into the volume as the liquid form of the
metal is discharged from the orifice. The method may further
include draining the liquid form of the metal from the volume,
through a media drain separate from the discharge orifice, as the
liquid form of the metal is discharged from the orifice.
[0022] An additive manufacturing system may include a nozzle
defining a volume and a discharge orifice in fluid communication
with one another, a build plate spaced apart from the discharge
orifice of the nozzle, a source of a pressurized gas, an electrical
power source, a valve actuatable to control fluid communication
between the source of the pressurized gas and the volume of the
nozzle, and a robotic system mechanically coupled to the nozzle,
where the robotic system is movable to move the discharge orifice
and the build plate relative to one another in three-dimensions.
The system may also include a controller in electrical
communication with the valve, the electrical power source, and the
robotic system, the controller configured to actuate the robotic
system to move the discharge orifice and the build plate relative
to one another along a controlled three-dimensional pattern, and
the controller further configured to activate the valve and the
power source, based at least in part on a position of the discharge
orifice along the controlled three-dimensional pattern, to
selectively switch between pneumatically actuated ejection and
electrically actuated ejection of a liquid form of a metal from the
discharge orifice to form a three-dimensional object on the build
plate.
[0023] Implementations may include one or more of the following
features. Selectively switching between pneumatically actuated
ejection and electrically actuated ejection may include selecting
the electrically actuated ejection along a border of the controlled
three-dimensional pattern and selecting the pneumatically actuated
ejection along an excursion away from the border of the controlled
three-dimensional pattern. Upon selection of the pneumatically
actuated ejection, the controller may actuate the valve to
establish fluid communication between the source of the pressurized
gas and the volume. Upon selection of the electrically actuated
ejection, the controller may actuate the power source to deliver
electric current to the volume. The controller may actuate the
power source to deliver a pulsed electric current to the
volume.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The systems and methods described herein are set forth in
the appended claims. However, for the purpose of explanation,
several implementations are set forth in the following
drawings:
[0025] FIG. 1 is a block diagram of an additive manufacturing
system for use with pneumatic jetting of metal to form a
three-dimensional object.
[0026] FIG. 2 shows a flowchart of an exemplary method of additive
manufacturing of metal using pneumatic jetting.
[0027] FIG. 3 is a schematic representation of a nozzle including
baffles.
[0028] FIG. 4 is a flowchart of an exemplary method of separating
liquid metal from sediment in a pneumatic jetting process for
additive manufacturing of metal.
[0029] FIG. 5 is a schematic representation of a nozzle including
an adjustable exhaust passage.
[0030] FIG. 6 is a flowchart of an exemplary method of adjusting
back pressure in a pneumatic jetting process for additive
manufacturing of metal.
[0031] FIG. 7 is a schematic representation of an additive
manufacturing system for use with pneumatically actuated jetting
and electrically actuated jetting of metal to form a
three-dimensional object.
[0032] FIG. 8 is a flowchart of an exemplary method of switching
between pneumatically actuated ejection and electrically actuated
ejection of liquid metal.
DESCRIPTION
[0033] Embodiments will now be described with reference to the
accompanying figures. The foregoing may, however, be embodied in
many different forms and should not be construed as limited to the
illustrated embodiments set forth herein.
[0034] All documents mentioned herein are hereby incorporated by
reference in their entirety. References to items in the singular
should be understood to include items in the plural, and vice
versa, unless explicitly stated otherwise or clear from the text.
Grammatical conjunctions are intended to express any and all
disjunctive and conjunctive combinations of conjoined clauses,
sentences, words, and the like, unless otherwise stated or clear
from the context. Thus, the term "or" should generally be
understood to mean "and/or" and so forth.
[0035] Recitation of ranges of values herein are not intended to be
limiting, referring instead individually to any and all values
falling within the range, unless otherwise indicated herein, and
each separate value within such a range is incorporated into the
specification as if it were individually recited herein. The words
"about," "approximately," or the like, when accompanying a
numerical value, are to be construed as indicating a deviation as
would be appreciated by one of ordinary skill in the art to operate
satisfactorily for an intended purpose. Ranges of values and/or
numeric values are provided herein as examples only, and do not
constitute a limitation on the scope of the described embodiments.
The use of any and all examples, or exemplary language ("e.g.,"
"such as," or the like) provided herein, is intended merely to
better illuminate the embodiments and does not pose a limitation on
the scope of the embodiments. No language in the specification
should be construed as indicating any unclaimed element as
essential to the practice of the embodiments.
[0036] In the following description, it is understood that terms
such as "first," "second," "top," "bottom," "up," "down," and the
like, are words of convenience and are not to be construed as
limiting terms.
[0037] Referring now to FIG. 1, a three-dimensional printer 100 can
include a nozzle 102, a source 104 of pressurized gas, a valve 106,
and a media supply 108. The nozzle 102 can define a volume 110 and
a discharge orifice 112 in fluid communication with one another.
The media supply 108 is in fluid communication with the volume 110
of the nozzle 102 and, as described in greater detail below, the
media supply 108 moves metal 114 into the volume 110 such that a
liquid form of the metal 114 is disposed in the volume 110 along
the discharge orifice 112. The valve 106 can be actuated to control
ejection of the liquid form of the metal from the discharge orifice
112. For example, the valve 106 can be moved to an open position to
allow pressurized gas to fill the volume 110. Continuing with this
example, as the pressurized gas fills the volume 110, the
pressurized gas exerts a pneumatic force on the liquid form of the
metal 114 along the discharge orifice 112. This pneumatic force can
eject the liquid form of the metal 114 through the discharge
orifice 112. Additionally, or alternatively, the valve 106 can be
moved to a closed position to interrupt movement of pressurized gas
into the volume 110 and, thus, interrupt ejection of the liquid
form of the metal 114 through the discharge orifice 112. Thus, more
generally, the valve 106 can be selectively actuated to control the
ejection of the liquid form of the metal 114 during fabrication of
a three-dimensional object 116.
[0038] In use, as described in greater detail below, movement of
the metal 114 into the volume 110 can be separate from actuation of
the valve 106, which can facilitate rapidly ejecting the liquid
form of the metal 110 from the nozzle 102 to form the
three-dimensional object 111. For example, by reducing or
eliminating the need to pause a fabrication process to replenish
liquid metal in a nozzle, the three-dimensional printer 100 can
advantageously increase the speed of fabricating the
three-dimensional object 116 through pneumatic jetting of a liquid
form of the metal 114. More generally, it should be appreciated
that the three-dimensional printer 100 can be substantially
continuously operated to fabricate one or a plurality of the
three-dimensional object 116, making the three-dimensional printer
100 well-suited, for example, to produce metallic objects at
throughput rates suitable for mass production of parts.
[0039] The nozzle 102 can further include a first port 118 and a
second port 120, each in fluid communication with the volume 110 of
the nozzle 102. Pressurized gas from the source 104 of pressurized
gas can enter the volume 110 of the nozzle 102 through first port
118 when the valve 106 is open. Additionally, or alternatively, the
second port 120 can be in fluid communication with a lower pressure
environment such that pressurized gas in the volume 110 of the
nozzle 102 can exit the nozzle 102 through the second port 120. The
lower pressure environment can be, for example, at atmospheric
pressure. Additionally, or alternatively, the lower pressure
environment can be a vacuum, which can facilitate producing a sharp
reduction in pressure once fluid communication between the volume
110 and the source 104 of pressurized gas is interrupted. In
certain implementations, a vacuum pressure can be applied briefly
at the second port 120, which can be useful for providing further
control over the pressure profile in the volume 110 during ejection
of the liquid form of the metal 114 from the discharge orifice
112.
[0040] The first port 118 and the second port 120 can be spaced
apart from one another along the volume 110 of the nozzle 102. For
example, the first port 118 and the second port 120 can be
substantially axially aligned with one another along the volume 110
of the nozzle 102. Such an alignment can be useful, for example,
for reducing the likelihood of exciting a resonant frequency in the
volume 110 as the pressurized air moves through the volume 110. In
certain instances, the first port 118 and the second port 120 can
define an axis substantially parallel to a plane containing the
discharge orifice 112. In this orientation, the pressurized gas is
indirectly directed to the discharge orifice 112, which can
advantageously dampen the impact of pressure fluctuations in the
incoming pressurized gas on the ejection of the liquid form of the
metal 114.
[0041] In some implementations, the discharge orifice 112 can be
oriented vertically such that the first port 118 and the second
port 120 are below the discharge orifice 112. In such instances,
the liquid form of the metal 114 ejected from the discharge orifice
112 can move in a direction opposite gravity to slow the velocity
of the liquid form of the metal 114. Such slower velocity can be
useful, for example, for achieving an appropriate shape of the
metal 114 deposited on the three-dimensional object 116.
[0042] In some implementations, the discharge orifice 112 of the
nozzle 102 may include an inert gas curtain around the discharge
orifice 112, e.g., in the form of a ring 113 or other similar
structure. This may be useful when operating in atmosphere or
similar conditions. Thus, in certain implementations, an inert gas
curtain may be disposed at least partially around the discharge
orifice 112.
[0043] The discharge orifice 112 of the nozzle 102 may also be
modified or otherwise treated to control the liquid form of the
metal 114 ejected from the discharge orifice 112. For example, the
geometry of the discharge orifice 112 may be adjustable. In certain
aspects, the discharge orifice 112 may be replaceable or switchable
with other discharge orifices 112 having different properties,
e.g., for controlling the liquid form of the metal 114 ejected from
the discharge orifice 112. For example, the discharge orifice 112
may be controlled to provide an initial condition where the liquid
form of the metal 114 has a meniscus wetting the surface tangent to
walls of the discharge orifice 112, e.g., by changing the geometry
of the discharge orifice 112 or through a treatment of the
discharge orifice 112. Similarly, the discharge orifice 112 may be
controlled to provide an initial condition where the liquid form of
the metal 114 has a meniscus that does not wet the surface tangent
to walls of the discharge orifice 112, e.g., by changing the
geometry of the discharge orifice 112 or through a treatment of the
discharge orifice 112.
[0044] The source 104 of pressurized gas can be, for example, a
pressurized tank. In certain implementations, the source 104 of the
pressurized gas can have a pressure above about 550 kPa. Further,
or instead, the pressurized gas can be inert with respect to the
liquid form of the metal. For example, in certain instances, the
pressurized gas can be nitrogen, argon, or air.
[0045] As the valve 106 is opened and the pressurized gas initially
enters the volume 110 through the first port 118, pressure in the
volume 110 initially increases. As described in greater detail
below, the pressure in the volume 110 can increase until the
pressure in the volume 110 is sufficient to overcome a flow
resistance associated with the second port 120. Upon closing the
valve 106, the movement of pressurized gas through the first port
118 can be interrupted, and pressure in the volume 110 can
dissipate as the pressurized gas exits the volume 110 through the
second port 120.
[0046] The metal 114 from the media supply 108 can be movable into
the volume 110 while the valve 106 is positioned (e.g., closed) to
interrupt fluid communication between the discharge orifice 112 and
the source 104 of pressurized gas. Thus, for example, the flow rate
of the metal from the media supply 108 into the volume 110 can be
decoupled from the flow of pressurized gas through the volume 110.
It should be appreciated that such decoupling can reduce the
likelihood that the liquid form of the metal 114 in the volume 110
will become inadvertently depleted as the pressurized gas ejects
the liquid form of the metal 114 through the discharge orifice 112.
More generally, movement of the metal 114 from the media supply 108
into the volume 110 while the movement of pressurized gas into the
volume 110 is interrupted can reduce the likelihood of interrupted
operation of the nozzle 102 and, thus, can facilitate continuous or
substantially continuous fabrication.
[0047] As used herein, the term "metal" shall be understood to
include pure metals, metal alloys, and composite materials
including one or more metallic components, unless otherwise
specified or made clear by the context. Accordingly, by way of
non-limiting example, the metal 114 can be any one or more of
aluminum, an aluminum alloy, tin, and solder.
[0048] In certain implementations, the media supply 108 can be in
fluid communication with the volume 110 through the second port
120. Thus, for example, the metal 114 can be moved (e.g.,
continuously) by the media supply 108 into the volume 110 through
the same passage through which the pressurized gas is exhausted
from the volume 110. It should be appreciated that such a
configuration can, for example, reduce the number of ports required
for the nozzle 102, which can facilitate reducing the size of the
nozzle 102, as compared to a nozzle having a larger number of
ports.
[0049] In some implementations, the nozzle 102 can further include
a media drain 122 in fluid communication with the volume 110 of the
nozzle 102. The metal 114 from the media supply 108 can move from
the volume 110 to the media drain 122 to be drained from the nozzle
102 (e.g., for recycling to the media supply 108. As an example,
the liquid form of the metal 114 moving through the volume 110 of
the nozzle 102, from the media supply 108 to the media drain 122,
can move between the discharge orifice 112 and the first port 118.
Accordingly, continuing with this example, pressurized gas moving
into the volume 110 through the first port 118 can exert a
pneumatic force on the liquid form of the metal 114 moving past the
discharge orifice 112 to eject the liquid form of the metal 114
through the discharge orifice 112. The movement of the liquid form
of the metal 114 from the media supply 108 to the media drain can,
for example, reduce the likelihood of sediment build-up in the
volume 110. It should be appreciated that such a reduction in
sediment build-up can reduce the likelihood of unintended blockage
of the discharge orifice 112 and, thus, can facilitate continuous
or substantially continuous ejection of the liquid form of the
metal 114 over long periods of time.
[0050] In general, the three-dimensional printer 100 can include a
control system 126 that can manage operation of the
three-dimensional printer 100 to fabricate the three-dimensional
object 116. For example, the control system 126 can be in
electrical communication with the valve 106 and a robotic system
128 mechanically coupled to one or more of the nozzle 102 and a
build plate 130. In use, the control system 126 can actuate the
robotic system 128 to move the nozzle 102 along a controlled
three-dimensional pattern and additionally, or alternatively, the
control system 126 can actuate the valve 106 to control ejection of
a liquid form of the metal 114 from the nozzle 102 as one or more
of the nozzle 102 and the build plate 130 are moved along the
controlled three-dimensional pattern. The controlled
three-dimensional pattern can be based on a three-dimensional model
134 stored, for example, in a database 132, such as a local memory
of a computer used as the control system 126, or a remote database
accessible through a server or other remote resource, or in any
other computer-readable medium accessible to the control system
126. In certain implementations, the control system 126 can
retrieve the three-dimensional model 134 in response to user input,
and generate machine-ready instructions for execution by the
three-dimensional printer 100 to fabricate the three-dimensional
object 116.
[0051] The robotic system 128 can be movable within a working
volume 136 of a build chamber 138 to position the nozzle 102 and
the build plate 130 relative to one another in the build chamber
138 along the controlled three-dimensional pattern to fabricate the
three-dimensional object 116. A variety of robotics systems are
known in the art and suitable for use as the robotic system 128
contemplated herein. For example, the robotic system 128 can
include a Cartesian or x-y-z robotics system employing a number of
linear controls to move independently in the x-axis, the y-axis,
and the z-axis within the build chamber 138. Additionally, or
alternatively, the robotic system 128 can include delta robots,
which can, in certain implementations, provide significant
advantages in terms of speed and stiffness, as well as offering the
design convenience of fixed motors or drive elements. Other
configurations such as double or triple delta robots can,
additionally or alternatively, be used and can increase range of
motion using multiple linkages. More generally, any robotics
suitable for controlled positioning of the nozzle 102 and the build
plate 130 relative to one another, especially within a vacuum or
similar environment, may form part of the robotic system 114,
including any mechanism or combination of mechanisms suitable for
actuation, manipulation, locomotion and the like within the build
chamber 138.
[0052] The build chamber 138 may include a relatively inert
atmosphere. The build chamber 138 may also or instead include a
vacuum. In this manner, the liquid form of the metal 114 may be
ejected into one or more of an inert atmosphere and a vacuum during
fabrication of a three-dimensional object 116.
[0053] The media supply 108 can include, for example, a drive chain
140 and a heater 142. In certain implementations, the metal 114 is
initially in a solid form, such as, for example, a continuous form
(e.g., wire) or a discrete form (e.g., a billet). For example, the
metal 114 can be supplied in discrete units one-by-one as billets
or the like into the heater 126. Additionally, or alternatively,
the metal 114 can be supplied from a spool or cartridge containing
the metal 114 in a wire form. For environmentally sensitive
materials, the media supply 108, the build chamber 138, or both,
can provide a vacuum environment for the metal 114. More generally,
one or more of the media supply 108 and the build chamber 120 can
maintain a suitably inert environment for handling of the metal
114, such as a vacuum, and oxygen-depleted environment, an inert
gas environment, or some gas or combination of gasses that are not
reactive with the metal 114 under the conditions maintained during
three-dimensional fabrication.
[0054] In implementations in which the metal is initially in a
solid form, the drive chain 140 can engage the metal and move the
metal into the heater 142, where a liquid form of the metal can be
formed. The heater 142 can be in fluid communication with the
nozzle 102 such that the liquid form of the metal is movable into
the nozzle as fluid communication between the pressurized gas and
the nozzle 102 is, for example, separately controlled by actuation
of the valve 106. While the media supply 108 is described as
including a solid form of the metal 110 initially, it should be
appreciated that, in some implementations, the metal 116 can
initially be in a liquid form without departing from the scope of
the present disclosure. In such implementations, the media supply
108 may, for example, feed a liquid form of the metal 116 into the
nozzle 102 through the force of gravity, through the use of a pump,
or a combination thereof.
[0055] The drive chain 140 can include, for example, any suitable
gears, compression pistons, or the like, for continuous or indexed
feeding of the metal 110 into the heater 142. In one aspect, the
drive chain 140 can include a plurality of rollers 144 between
which a solid form of the metal 114 can be pinched such that
rotation of the plurality of rollers can move the solid form of the
metal 114 into the heater 142.
[0056] The heater 142 can heat the solid form of the metal 114
beyond a melt temperature of the metal 114 to form a liquid form of
the metal 114. Any number of heating techniques may be used. In one
aspect, electrical techniques such as inductive or resistive
heating may be usefully applied to liquefy the metal 114. This can
include, for example, inductively or resistively heating a chamber
around the metal 114. Additionally, or alternatively, the heater
142 can include one or more of induction heating and radiative
heating to liquefy the metal 114.
[0057] While the heater 142 is shown as being outside of the nozzle
102, it should be appreciated, that the heater 142 can be,
additionally or alternatively, integrated into the nozzle 102 such
that, for example, a solid form of the metal 110 is moved from the
metal supply into the nozzle 102 and the solid form of the metal
110 is melted as it passes into the nozzle 102. In such
implementations, the heater 142 can, for example, direct heat in
the vicinity of the discharge orifice 112. In general, direction of
heat in the vicinity of the discharge orifice 112 can reduce the
likelihood of solidification of the liquid form of the metal 114 in
the discharge orifice 112 and, thus, can reduce the likelihood of
the nozzle 102 seizing or otherwise becoming inoperable during a
fabrication process. For example, the heater 142 can reduce the
likelihood of solidification of the liquid form of the metal 114 in
or near the discharge orifice 112 during a quiescent state in which
the liquid form of the metal 114 is not being ejected from the
discharge orifice 112 (e.g., between part fabrications).
[0058] The heater 142 can also or instead include any other heating
systems suitable for applying heat to the metal 110 to a suitable
temperature for producing or maintaining a liquid form of the metal
110. Thus, the heater 106 described herein should be understood to
include generally any system that places a solid form of the metal
110 in condition for use in fabrication as contemplated herein and
further includes any system that maintains a liquid form of the
metal 114 in condition for use in fabrication as contemplated
herein. In certain implementations, the system 100 can further
include a heater 124 disposed along a portion of the nozzle 102
adjacent (e.g., directly adjacent) to the discharge orifice
112.
[0059] FIG. 2 shows a flowchart of an exemplary method 200 of
additive manufacturing of metal using pneumatic jetting. The method
200 can be carried out using any one or more of the devices and
systems described herein, unless otherwise specified or made clear
from the context. Thus, for example, it should be understood that
the method 200 can be carried out using the three-dimensional
printer 100 described above with respect to FIG. 1.
[0060] As shown in step 202, the method 200 may include directing a
metal into a volume defined by the nozzle. For example, a solid
form of the metal can be directed into the volume defined by the
nozzle. In certain implementations, the solid form of the metal can
be liquefied within the volume defined by the nozzle. Additionally,
or alternatively, the metal can be liquefied outside of the volume
defined by the nozzle and delivered into the volume in a liquid
form.
[0061] As shown in step 204, the method 200 can include moving a
discharge orifice and a build plate relative to one another along a
controlled three-dimensional pattern. Such relative movement can be
achieved in one or more of various different combinations of
movement of the discharge orifice and the build plate. For example,
the discharge orifice can be moved along the controlled
three-dimensional pattern while the build plate remains stationary.
Additionally, or alternatively, the build plate can be moved along
the controlled three-dimensional pattern while the discharge
orifice remains stationary. Further or instead, the discharge
orifice and the build plate can each be moved along the controlled
three-dimensional pattern.
[0062] The discharge orifice can be defined by the nozzle and in
fluid communication with the volume such that the liquid form of
the metal can move from the volume through the discharge orifice as
the discharge orifice and the build plate are moved relative to one
another along the controlled three-dimensional pattern. In certain
implementations, a robotic system can move the discharge orifice
and the build plate relative to one another along the controlled
three-dimensional pattern. The robotic system can be, for example,
any one or more of the various different robotic systems described
herein or otherwise known in the art. Additionally, or
alternatively, actuation of the robotic system to move the
discharge orifice and the build plate relative to one another can
be controlled by a control system, such as any one or more of the
various control systems described herein. For example, the control
system can control actuation of the robotic system based at least
in part upon a three-dimensional model received by the control
system.
[0063] As shown in step 206, the method 200 can include selectively
delivering pulses of pressurized gas into the volume to eject a
liquid form of the metal from the discharge orifice to form a
three-dimensional object. The selective delivery of the pulses can
be, for example, based at least in part on a position of the
discharge orifice along the controlled three-dimensional pattern.
In certain implementations, the metal can be directed into the
volume according to step 202 while the pulses of pressurized gas
are selectively delivered into the volume. In some implementations,
the metal in the liquid form can be drained from the volume of the
nozzle as the pulses of pressurized gas are selectively delivered
into the volume. Thus, more generally, the metal can be moved in
and out of the volume of the nozzle independently of delivery of
the pressurized gas into the volume of the nozzle.
[0064] Further, or instead, selectively delivering pulses of
pressurized gas into the volume to eject the liquid form of the
metal can include ejecting the liquid form of the metal from the
discharge orifice in a direction having a vertical component
substantially opposite a direction of gravity. It should be
understood that the ejection of the liquid form of the metal in
this direction can advantageously slow down the ejected liquid form
of the metal to achieve desired contact between the ejected liquid
form of the metal and a three-dimensional object being
fabricated.
[0065] In certain implementations, selectively delivering pulses of
pressurized gas into the volume to eject the liquid form of the
metal can include controlling the pulse frequency. The pulse
frequency may be controlled or tuned to increase a stability of a
meniscus of the liquid metal prior to droplet ejection, e.g.,
between each ejection. In certain aspects, the pulse frequency may
be tuned in multiples of the natural harmonics of the volume of the
nozzle.
[0066] While certain implementations have been described, other
implementations are additionally, or alternatively, possible.
[0067] For example, while nozzles have been described as having an
unimpeded path between metal entering the nozzle and a discharge
orifice through which metal is ejected from the nozzle, other
configurations are additionally or alternatively possible. As an
example, referring now to FIG. 3, a nozzle 300 can define a volume
302, a first port 304, a second port 306, and a discharge orifice
308 in fluid communication with one another. In general, unless
otherwise specified or made clear from the context, the nozzle 300
can be used in addition to or in place of the nozzle 102 of the
three-dimensional printer 100 described above with respect to FIG.
1. Thus, for example, the nozzle 300 can be in selective fluid
communication with pressurized gas from a source of pressurized
gas, such as the source 104 of the pressurized gas described above
with respect to FIG. 1, with the fluid communication with the
volume 302 being through the first port 304. Similarly, the nozzle
300 can receive metal from a media supply, such as the media supply
108 described above with respect to FIG. 1, in fluid communication
with the volume 302 of the nozzle through the second port 306.
Thus, for example, it should be understood that the nozzle 300 can
receive a solid form of metal through the second port 306 and,
additionally or alternatively, the second port 306 can be vented to
one or both of an atmospheric pressure and a vacuum pressure such
that pressurized gas can exit the volume through the second port
306.
[0068] The nozzle 300 can include one or more baffles 310 disposed
in the volume 302 (e.g., a plurality of baffles 310 arranged
substantially parallel to one another). In general, the baffles 310
can be oriented to direct sediment toward a reservoir portion 312
of the volume 302. The reservoir portion 312 can be away from the
discharge orifice 308 of the nozzle 300 such that sediment directed
toward the reservoir portion 312 remains away from the discharge
orifice 308 as the liquid metal is ejected from the discharge
orifice 308 during use of the nozzle 300.
[0069] In certain implementations, an axis defined by the discharge
orifice 308 and the second port 306 intersects the one or more
baffles 310. In such implementations, the flow of metal moving into
the volume 302 through the second port 306 will be disturbed by the
one or more baffles 310 as the metal moves toward the discharge
orifice 308. It should be appreciated that such disturbance of the
flow of the metal can be useful for directing sediment toward the
reservoir portion 312 of the volume 302. Further, or instead, the
one or more baffles 310 can be angled, for example, with respect to
an axis perpendicular to the discharge orifice 308 to direct
sediment, for example, toward the reservoir portion 312 of the
volume 302.
[0070] In some implementations, the one or more baffles 310 can
span a dimension of the volume 302 of the nozzle 300. For example,
the one or more baffles 310 can span a depth of the volume 302 and
span less than the entirety of the width of the volume 302. In
general, spanning a dimension of the volume 302 with the one or
more baffles 310 can increase the likelihood that the flow of the
liquid metal from the second port 306 toward the discharge orifice
308 will be directed to the reservoir portion 312 before reaching
the discharge orifice 308.
[0071] In addition, or in the alternative, the one or more baffles
310 can define a non-linear path between the discharge orifice 308
and the reservoir portion 312. As an example, the non-linear path
can include a section increasing in height, along an axis
perpendicular to the discharge orifice 308 such that liquid metal
moving from the reservoir portion 312 toward the discharge orifice
308 follows the increase in height. Such an increase in height can
be useful for separating sediment from the liquid metal before the
liquid metal reaches the discharge orifice. More generally, a
non-linear path can be useful, for example, for reducing the
likelihood that sediment will migrate from the reservoir portion
312 to the discharge orifice 308 during sustained use of the nozzle
300 to eject a liquid form of a metal.
[0072] In general, pressurized gas can be moved through the volume
302, from the first port 304 to the second port 306, in any one or
more of various different directions. It should be appreciated,
however, that certain orientations of the first port 304 and the
second port 306 can be advantageous for efficient and accurate
operation of the nozzle 300 to eject liquid metal. Thus, in certain
implementations, the flow of pressurized gas through the first port
304 can be substantially unimpeded by the one or more baffles 310
such that the one or more baffles 310 do not slow down the movement
of pressurized gas into the volume 300 during use.
[0073] The nozzle 300 can, in some implementations, include a
heater 314. The heater 314 can, for example, direct heat along at
least portions of the nozzle 300 defining the discharge orifice 308
and along which the one or more baffles 310 are disposed. The
application of heat along such portions of the nozzle 300 can
reduce the likelihood that the liquid metal will solidify as the
liquid metal is moving along the one or more baffles 310 and toward
the discharge orifice 308. The heater 314 can include, for example,
one or more of a resistance heater, an induction heater, a
convection heater, and a radiation heater.
[0074] FIG. 4 is a flowchart of an exemplary method 400 of
separating liquid metal from sediment in a pneumatic jetting
process for additive manufacturing of metal. The method 400 can be
carried out using any one or more of the three-dimensional printers
described herein, unless otherwise specified or made clear from the
context. Thus, for example, the method 400 can be carried out using
a three-dimensional printer, such as the three-dimensional printer
100 described above with respect to FIG. 1, including the nozzle
300 described above with respect to FIG. 3.
[0075] As shown in step 402, the method 400 can include directing a
metal into a volume defined by a nozzle. In general, the metal can
be directed into the volume according to any one or more of the
methods described herein. Thus, for example, a solid form of the
metal can be directed into the volume defined by the nozzle such
that the solid form of the metal can be liquefied within the volume
defined by the nozzle. Additionally, or alternatively, the metal
can be liquefied outside of the volume defined by the nozzle and
delivered into the volume in a liquid form.
[0076] As shown in step 404, the method 400 can include moving a
discharge orifice and a build plate relative to one another along a
controlled three-dimensional pattern. The discharge orifice can be
defined by the nozzle and in fluid communication with the volume
such that metal in the volume can move through the discharge
orifice along the controlled three-dimensional pattern. It should
be appreciated that the relative movement of the discharge orifice
and the build plate can be achieved by moving one or both of the
discharge orifice and the build plate relative to one another.
[0077] As shown in step 406, the method 400 can include separating
a liquid form of the metal from a sediment. The separation can take
place, for example, in the volume defined by the nozzle, and the
volume can define a sediment reservoir. The separation can include,
for example, moving the liquid form of the metal along a non-linear
path from the sediment reservoir to the discharge orifice (e.g., a
non-linear path at least partially defined by baffles disposed in
the volume defined by the nozzle). The movement of the liquid form
of the metal along the non-linear path can facilitate, for example,
separation of the liquid form of the metal from the sediment.
Additionally, or alternatively, separating the liquid form of the
metal from the sediment can include increasing, in the volume of
the nozzle, a height of the liquid form of the metal relative to
the discharge orifice. As the height of the liquid form of the
metal increases, the sediment will settle and, thus, separate from
the liquid form of the metal.
[0078] As shown in step 408, the method 400 can include delivering
pressurized gas into the volume to eject the liquid form of the
metal from the discharge orifice to form a three-dimensional
object. The delivery of the pressurized gas can be, for example,
based at least in part on a position of the discharge orifice along
the controlled three-dimensional pattern such that the ejected
metal can be accurately delivered to the three-dimensional object
being fabricated. Additionally, or alternatively, the separation of
the liquid form of the metal from the sediment in step 406 can
occur while the pressurized gas is delivered into the volume such
that the separation of the liquid metal from the sediment does not
significantly impact the speed of fabrication of the
three-dimensional object.
[0079] As another example, while nozzles have been described as
having a fixed pressure profile, other implementations are
additionally or alternatively possible. As an example, referring
now to FIG. 5, a nozzle 500 can define a volume 502, a first port
504, a second port 506, and a discharge orifice 508 in fluid
communication with one another. Further, or instead, the nozzle 500
can include an exhaust passage 510, as described in greater detail
below. In general, unless otherwise specified or made clear from
the context, the nozzle 500 can be used in addition to or in place
of the nozzle 102 of the three-dimensional printer 100 described
above with respect to FIG. 1 or the nozzle 300 described above with
respect to FIG. 3. Thus, for example, the nozzle 500 can be in
selective fluid communication with pressurized gas from a source of
pressurized gas, such as the source 104 of the pressurized gas
described above with respect to FIG. 1, with the fluid
communication with the volume 502 being through the first port 504.
Similarly, the nozzle 500 can receive metal from a media supply,
such as the medial supply 108 described above with respect to FIG.
1, which can be in fluid communication with the volume 502 through
the second port 306. Thus, for example, it should be understood
that the nozzle 300 can receive a solid form of metal through the
second port 506 and, additionally or alternatively, the second port
506 can be vented through the exhaust passage 510.
[0080] The exhaust passage 510 can have an adjustable back
pressure. In general, such adjustable back pressure can be useful
for controlling a pressure profile in the volume 502 defined by the
nozzle 500 as pressurized gas moves through the volume 502 to eject
a liquid form of the metal from the discharge orifice 508 (e.g.,
along a controlled three-dimensional pattern for fabrication of a
three-dimensional object). As used herein, the pressure profile in
the volume 502 includes pressure in the volume 502 as a function of
time. It should be appreciated that characteristics of the pressure
profile (e.g., rate of pressure rise, peak pressure, rate of
pressure decay, and duration) can impact the shape of droplets
ejected from the discharge orifice 508 in response to pulsations of
the pressurized gas in the nozzle 500.
[0081] In certain implementations, the exhaust passage 510 can
include a hydraulic inductance 512. As pressurized gas moves
through the hydraulic inductance 512, the hydraulic inductance 512
can have a dissipating resistance, over time, in response to force
exerted on the hydraulic inductance 512 as the pressurized gas
exits the volume 502 through the exhaust passage 510. For example,
as pressurized gas is initially introduced to the hydraulic
inductance 512, the flow resistance of the hydraulic inductance 512
can be high such that pressure builds in the volume 502. Continuing
with this example, as the pressurized gas continues to exert force
on the hydraulic inductance 512, the flow resistance of the
hydraulic inductance 512 can decrease such that the built-up
pressure in the volume 502 can dissipate as the pressurized gas
moves through the hydraulic inductance 512 at a higher rate.
[0082] As an example, the hydraulic inductance 512 can include a
paddle wheel 514. In use, the paddle wheel 514 can rotate in
response to force exerted on the paddle wheel 514 by the venting
pressurized gas in the exhaust passage 510. The paddle wheel 514
can have an inertia that must be overcome before the paddle wheel
514 can rotate freely. It should be appreciated that the force of
the pressurized gas on the paddle wheel 514 prior to overcoming the
inertia can correspond to a rise in pressure in the volume 502. As
the pressurized gas continues to be exerted on the paddle wheel 514
and the inertia is overcome, the paddle wheel 514 can rotate freely
such that the paddle wheel 514 exerts little to know resistance on
the flow of the pressurized gas.
[0083] In certain implementations, the time-varying profile of the
resistance of the hydraulic inductance 512 can be adjustable to
facilitate achieving a desired pressure profile (e.g., in
real-time) in the volume 502. Such adjustability can be useful, for
example, for controlling the size and shape of droplets ejected
from the discharge orifice 508. For example, in implementations in
which the hydraulic inductance 512 includes the paddle wheel 514, a
rotational resistance of the paddle wheel 514 can be adjusted to
change the time-varying profile of the resistance of the hydraulic
inductance 512.
[0084] In certain implementations, the exhaust passage 510 can
include a variable hydraulic resistance 516. As an example, the
variable hydraulic resistance 516 can include a variable length of
the exhaust passage 510, with longer lengths generally
corresponding to increased hydraulic resistance. Additionally, or
alternatively, the variable hydraulic resistance 516 can include a
flow restriction (e.g., an orifice) having a variable size. In
certain implementations, the variable hydraulic resistance 516 can
be adjusted to achieve a target pressure profile (e.g., in
real-time) in the volume 502.
[0085] FIG. 6 is a flowchart of an exemplary method 600 of
adjusting back pressure in a pneumatic jetting process for additive
manufacturing of metal. The method 600 can be carried out using any
one or more of the three-dimensional printers described herein,
unless otherwise specified or made clear from the context. Thus,
for example, the method 600 can be carried out using a
three-dimensional printer, such as the three-dimensional printer
100 described above with respect to FIG. 1, including the nozzle
500 described above with respect to FIG. 5.
[0086] As shown in step 602, the method 600 can include directing a
metal into a volume defined by the nozzle. In general, the metal
can be directed into the volume according to any one or more of the
methods described herein. Thus, for example, a solid form of the
metal can be directed into the volume defined by the nozzle such
that the solid form of the metal can be liquefied within the volume
defined by the nozzle. Additionally, or alternatively, the metal
can be liquefied outside of the volume defined by the nozzle and
delivered into the volume in a liquid form.
[0087] As shown in step 604, the method 600 can include moving a
discharge orifice and a build plate relative to one another along a
controlled three-dimensional pattern. The discharge orifice can be
defined by the nozzle and in fluid communication with the volume
such that a liquid form of the metal can be ejected through the
discharge orifice as the discharge orifice and the build plate are
moved relative to one another along the controlled
three-dimensional pattern.
[0088] As shown in step 606, the method 600 can include delivering
pulses of pressurized gas into the volume of the nozzle. For
example, delivering pulses of pressurized gas can include
repeatedly actuating a valve disposed between the volume and a
source of the pressurized gas according to any one or more of the
various different methods described herein. It should be
appreciated that, in general, the characteristics of the pulsations
(e.g., amplitude and rate) can be a function of the shape and size
of liquid metal droplets desired for a given position along the
controlled three-dimensional pattern.
[0089] As shown in step 608, the method 600 can include adjusting a
back pressure of an exhaust passage in fluid communication with the
volume of the nozzle and through which the pressurized gas is
vented from the volume of the nozzle. In general, in response to
the adjustment of the back pressure, the pressurized gas in the
volume can exert a force (e.g., a changing force) on the liquid
form of the metal in the volume to eject the liquid metal from the
discharge orifice. As the discharge orifice and the build plate are
moved relative to one another along the controlled
three-dimensional pattern, the ejected liquid metal can accumulate
to form a three-dimensional object on the build plate.
[0090] Adjusting the back pressure in step 608 can include any one
or more of the adjustments described above with respect to the
nozzle 500 of FIG. 5. As an example, adjusting the back pressure in
step 608 can include venting the pressurized gas through a
hydraulic inductance having a dissipating resistance to flow in
response to force exerted by the venting pressurized gas. In
general, the hydraulic inductance can be any of the various
different hydraulic inductances described herein and, therefore,
can include a paddle wheel (e.g., the paddle wheel 514 of FIG. 1)
or other similar devices. The dissipating resistance can have a
profile suited to achieving a desired pressure profile in the
volume as the pressurized gas is pulsed in the volume. In certain
implementations, the dissipating resistance can dissipate to a
substantially constant hydraulic resistance in the exhaust passage.
Additionally, or alternatively, the period of time over which the
resistance dissipates can be less than a period of the pulses of
the pressurized gas in the volume. Such a rapid dissipation can be
useful, for example, for controlling the size and shape of the
ejected liquid metal.
[0091] As an additional, or alternative, example, adjusting the
back pressure in step 608 can include venting the pressurized gas
through a variable hydraulic resistance and adjusting the variable
hydraulic resistance. For example, the hydraulic resistance can be
varied based at least in part on a position of the discharge
orifice with respect to the controlled three-dimensional pattern.
It should be appreciated that varying hydraulic resistance can
include any one or more of the methods of varying hydraulic
resistance described herein and, therefore, can include one or more
of varying size of a flow restriction and varying a length of an
exhaust passage.
[0092] In certain implementations, adjusting the back pressure of
the exhaust passage in step 608 can be based on a volume of the
liquid form of the metal in the volume of the nozzle. As an
example, the back pressure can be adjusted to a higher pressure as
the volume of the liquid form of the metal in the volume of the
nozzle increases. The higher back pressure can correspond to a
higher pressure in the volume. In turn, the increase in back
pressure can increase the amount of the liquid form of the metal
ejected from the discharge orifice and, thus, reduce the volume of
the liquid form of the metal in the volume of the nozzle. It should
be appreciated that a reduction in the back pressure can decrease
the amount of the liquid form of the metal ejected from the
discharge orifice and, thus, increase the volume of the liquid form
of the metal in the volume of the nozzle.
[0093] As another example, while additive manufacturing systems
have been described as including pneumatic jetting, other
configurations are additionally or alternatively possible. For
example, referring now to FIG. 7, a three-dimensional printer 700
switchable between pneumatically actuated ejection and electrically
actuated ejection. Unless otherwise specified or made clear by the
context, elements having "700" series element numbers are the same
as elements having analogous "100" series element numbers in FIG.
1. Thus, for example, the robotic system 708 in FIG. 7 should be
understood to be analogous to the robotic system 108 in FIG. 1,
unless otherwise specified or made clear from the context.
Accordingly, for the sake of efficient explanation, elements having
"700" series element numbers are not described separately from the
analogous elements having "100" series element numbers, except to
point out features related to switching between pneumatically
actuated ejection and electrically actuated ejection. As used
herein, "pneumatically actuated ejection" should be understood to
include ejection of liquid metal through the application of a
pneumatic force exerted, directly or indirectly, on the liquid
metal through the force of a pressurized gas. Also, as used herein,
"electrically actuated ejection" should be understood to include
ejection of liquid metal through the application of a
magnetohydrodynamic force, an electrohydrodynamic force, or an
electro-mechanically actuated force on the liquid metal.
[0094] The three-dimensional printer 700 can include a control
system 726 in electrical communication with a valve 706 and an
electrical power source 709. The valve 706 can be actuatable to
control fluid communication between a source 704 of pressurized gas
and a volume 710 defined by a nozzle 702, as described above with
respect to the valve 106 in FIG. 1. electrical communication with
the nozzle 702 and the control system 726. In use, the control
system 726 can control the valve 706 and the electrical power
source 709 to selectively switch between pneumatically actuated
ejection and electrically actuated ejection of a liquid form of a
metal 714 from a discharge orifice 712 defined by the nozzle
702.
[0095] In certain implementations, the control system 726 can place
the nozzle 702 in a pneumatically actuated ejection mode by
actuating the valve 706 to establish fluid communication between
the source 704 of pressurized gas and the volume 710 defined by the
nozzle 702 to eject a liquid form of the metal 714 according to any
one or more of the methods described herein. In the pneumatically
actuated ejection mode, the control system 726 can, optionally,
interrupt electrical communication between the electrical power
source 709 and the nozzle 702.
[0096] Further, or instead, the control system 726 can place the
nozzle 702 in an electrically actuated ejection mode by actuating
the valve 706 to interrupt fluid communication between the source
704 of pressurized gas and the volume 710 and actuating the
electrical power source 709 to deliver electric current to the
nozzle 702. It should be appreciated that the electric current can
be, for example, a pulsed electric current to eject discrete liquid
metal droplets (e.g., drop-on-demand) from the discharge orifice
712. In certain implementations, the electric current can be
directed into the liquid form of the metal in the nozzle 702, where
the electric current can intersect a magnetic field extending
through the liquid form of the metal to create a
magnetohydrodynamic force to eject the liquid form of the metal 714
from the discharge orifice 712. In some implementations, the
electric current can be directed into the liquid form of the metal
in the nozzle 702, where the electric current can interact with an
electric charge of the liquid form of the metal 714 to create an
electrohydrodynamic force to eject the liquid form of the metal 714
from the discharge orifice 712. Additionally, or alternatively, the
electric current can be directed to an actuator 727 (e.g., a
piezoelectric actuator) in contact with the liquid form of the
metal 714 such that actuation of the actuator 727 exerts a
mechanical force on the liquid form of the metal 714 to ejection
the liquid form of the metal 714 from the discharge orifice
712.
[0097] In some implementations, the control system 726 can actuate
the valve 706 and the electrical power source 709 to switch between
pneumatically actuated ejection and electrically actuated ejection
based at least in part on a position of the discharge orifice 712
along a controlled three-dimensional patter. As an example, the
control system 726 can actuate the valve 706 and the electrical
power source 709 for electrically actuated ejection along a border
of the controlled three-dimensional pattern or another similar
region requiring a high degree of accuracy of placement of liquid
metal droplets. As an additional or alternative example, the
control system 726 can actuate the valve 706 and the electrical
power source 709 for pneumatically actuated ejection along an
excursion away from the border (e.g., within an interior space
defined by the border) of the controlled three-dimensional pattern
or along another similar region requiring less accuracy in
placement of liquid metal. More generally, the control system 726
can actuate the valve 706 and the electrical power source to switch
between ejection of a stream of the liquid form of the metal 714
(in the pneumatically actuated ejection mode) and ejection of
discrete droplets of the liquid form of the metal 714 (in the
electrically actuated ejection mode).
[0098] FIG. 8 is a flowchart of an exemplary method 800 of
switching between pneumatically actuated jetting and electrically
actuated jetting of a liquid form of a metal. It should be
appreciated that the exemplary method 800 can be carried out using,
for example, the three-dimensional printer 700 described above with
respect to FIG. 7.
[0099] As shown in step 802, the exemplary method 800 can include
directing a metal into a volume defined by nozzle. In general, the
metal can be directed into the volume according to any one or more
of the methods described herein and, thus, can include movement of
the metal through the use of any one or more of the media supplies
described herein.
[0100] As shown in step 804, the exemplary method 800 can include
moving a discharge orifice and a build plate relative to one
another along a controlled three-dimensional pattern. The discharge
orifice can any one or more of the discharge orifices described
herein and, thus, can be defined by the nozzle and in fluid
communication with the volume. The discharge orifice and the build
plate can be moved relative to one another through the use of a
robotic system, such as the robotic systems 108 and 708 described
above.
[0101] As shown in step 806, the exemplary method 800 can include
selectively switching between pneumatically actuated ejection and
electrically actuated ejection of a liquid form of the metal from
the discharge orifice. The selective switching can be, for example,
based at least upon a position of the discharge orifice along the
controlled three-dimensional pattern. As an example, the selective
switching can include selecting electrically actuated ejection
along a border of the controlled three-dimensional pattern (e.g.,
to deliver discrete droplets along the border, where more accuracy
may be required to be meet part specifications). Additionally, or
alternatively, the selective switching can include selecting
pneumatically actuated ejection along an excursion away from the
border of the controlled three-dimensional pattern. Such pneumatic
ejection can be useful, for example, within the border, where
accurate placement of the liquid metal may be less critical. Thus,
for example, in such regions within the border, the pneumatic
ejection can deliver a constant or substantially constant stream of
liquid metal to in-fill the part and, thus, speed up the
manufacturing process.
[0102] As shown in step 808, the exemplary method 800 can include
ejecting the liquid metal from the discharge orifice according to
the selected one of the pneumatically actuated ejection and the
electrically actuated ejection to form at least a portion of a
three-dimensional object.
[0103] The above systems, devices, methods, processes, and the like
may be realized in hardware, software, or any combination of these
suitable for a particular application. The hardware may include a
general-purpose computer and/or dedicated computing device. This
includes realization in one or more microprocessors,
microcontrollers, embedded microcontrollers, programmable digital
signal processors or other programmable devices or processing
circuitry, along with internal and/or external memory. This may
also, or instead, include one or more application specific
integrated circuits, programmable gate arrays, programmable array
logic components, or any other device or devices that may be
configured to process electronic signals. It will further be
appreciated that a realization of the processes or devices
described above may include computer-executable code created using
a structured programming language such as C, an object oriented
programming language such as C++, or any other high-level or
low-level programming language (including assembly languages,
hardware description languages, and database programming languages
and technologies) that may be stored, compiled or interpreted to
run on one of the above devices, as well as heterogeneous
combinations of processors, processor architectures, or
combinations of different hardware and software. In another aspect,
the methods may be embodied in systems that perform the steps
thereof, and may be distributed across devices in a number of ways.
At the same time, processing may be distributed across devices such
as the various systems described above, or all of the functionality
may be integrated into a dedicated, standalone device or other
hardware. In another aspect, means for performing the steps
associated with the processes described above may include any of
the hardware and/or software described above. All such permutations
and combinations are intended to fall within the scope of the
present disclosure.
[0104] Embodiments disclosed herein may include computer program
products comprising computer-executable code or computer-usable
code that, when executing on one or more computing devices,
performs any and/or all of the steps thereof. The code may be
stored in a non-transitory fashion in a computer memory, which may
be a memory from which the program executes (such as random access
memory associated with a processor), or a storage device such as a
disk drive, flash memory or any other optical, electromagnetic,
magnetic, infrared or other device or combination of devices. In
another aspect, any of the systems and methods described above may
be embodied in any suitable transmission or propagation medium
carrying computer-executable code and/or any inputs or outputs from
same.
[0105] The method steps of the implementations described herein are
intended to include any suitable method of causing such method
steps to be performed, consistent with the patentability of the
following claims, unless a different meaning is expressly provided
or otherwise clear from the context. So, for example performing the
step of X includes any suitable method for causing another party
such as a remote user, a remote processing resource (e.g., a server
or cloud computer) or a machine to perform the step of X.
Similarly, performing steps X, Y and Z may include any method of
directing or controlling any combination of such other individuals
or resources to perform steps X, Y and Z to obtain the benefit of
such steps. Thus, method steps of the implementations described
herein are intended to include any suitable method of causing one
or more other parties or entities to perform the steps, consistent
with the patentability of the following claims, unless a different
meaning is expressly provided or otherwise clear from the context.
Such parties or entities need not be under the direction or control
of any other party or entity, and need not be located within a
particular jurisdiction.
[0106] It should further be appreciated that the methods above are
provided by way of example and not limitation. Absent an explicit
indication to the contrary, the disclosed steps may be modified,
supplemented, omitted, and/or re-ordered without departing from the
scope of this disclosure. Numerous variations, additions,
omissions, and other modifications will be apparent to one of
ordinary skill in the art. In addition, the order or presentation
of method steps in the description and drawings above is not
intended to require this order of performing the recited steps
unless a particular order is expressly required or otherwise clear
from the context. Thus, while particular embodiments have been
shown and described, it will be apparent to those skilled in the
art that various changes and modifications in form and details may
be made therein without departing from the spirit and scope of this
disclosure and are intended to form a part of the invention as
defined by the following claims, which are to be interpreted in the
broadest sense allowable by law.
* * * * *