Note: Descriptions are shown in the official language in which they were submitted.
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WIRE FORCE SENSOR FOR WIRE FEED DEPOSITION PROCESSES
CROSS-REFERENCE
[0001] This application claims the benefit of U.S. Provisional Patent
Application Serial No.
62/715,373, filed August 7, 2018, which is entirely incorporated herein by
reference.
BACKGROUND
[0002] Wire feeding techniques are widely used in a number of different
applications
including wire welding and additive manufacturing. A wire feeder may comprise
a roller that is
in frictional contact with a wire to advance the wire towards a wire receiver.
[0003] In a welding apparatus (e.g., an apparatus for gas metal arc welding
or flux-cored arc
welding), a wire feeder may be used to feed a wire from a wire source (e.g. a
metal wire spool)
to a nozzle of a welding gun. The welding gun may create heat to melt a
portion of the wire and
a work piece to form a pool of molten metal. The pool of molten metal may cool
and solidify on
the work piece. The pool of molten metal may join a plurality of work pieces.
[0004] Additive manufacturing techniques such as three-dimensional (3D)
printing may also
use wire feeding techniques. In an example, a polymeric material may be pulled
by a wire feeder
from a source into a nozzle, then melted, and subsequently deposited into a
specified pattern in a
layer-by-layer fashion to form a 3D object.
SUMMARY
[0005] The present disclosure provides systems and methods of feedstock
feeding that may
help avoid various disadvantages of other feedstock feeding methods and
systems. Systems and
methods of the present disclosure enable a feedstock to be directed from a
source of the
feedstock (e.g., a wire spool) to a feedstock receiver in a manner that
reduces stress(es) while
sensing forces imposed on the feedstock. This may advantageously increase the
longevity of
various components of systems of the present disclosure.
[0006] In an aspect, the present disclosure provides a method for printing
at least a portion of
a three-dimensional (3D) object adjacent to a support, or a deposited portion
of the 3D object,
comprising: (a) directing a first portion of at least one wire toward and in
contact with the
support, or the deposited portion of the 3D object, in accordance with at
least one parameter; (b)
upon contacting the at least one wire with the support, or the deposited
portion of the 3D object,
using one or more sensors to generate a signal(s) indicative of a reaction
force exerted by the
support, or the deposited portion of the 3D object, against the at least one
wire, to provide a
measured value; (c) adjusting the at least one parameter in response to the
measured value to
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provide at least one adjusted parameter; and (d) bringing a second portion of
the at least one wire
toward and in contact with the support, or the deposited portion of the 3D
object, in accordance
with the at least one adjusted parameter.
[0007] In some embodiments, the at least one parameter is adjusted when the
reaction force
exceeds a threshold value. In some embodiments, the method for printing at
least a portion of a
3D object further comprises subjecting the second portion of the at least one
wire to heating
upon flow of electrical current through the at least one wire and into the
support, or the deposited
portion of the 3D object, or vice versa, which heating is sufficient to melt
the second portion of
the at least one wire. In some embodiments, the method for printing at least a
portion of a 3D
object further comprises depositing the second portion of the at least one
wire on the support, or
the deposited portion of the 3D object, thereby forming the at least the
portion of the 3D object.
[0008] In some embodiments, the first portion of the at least one wire is
directed through a
wire feeding assembly. In some embodiments, the at least one parameter is
selected from the
group consisting of a wire feed speed, distance between a tip of the at least
one wire and the
support or the deposited portion of the 3D object, distance between the tip of
the at least one wire
and the at least the portion of the 3D object, amount of power applied to the
wire feeding
assembly, amount of current applied to the wire feeding assembly, and amount
of voltage
applied to the wire feeding assembly. In some embodiments, the one or more
sensors are
kinematically mounted to hold the wire feeding assembly. In some embodiments,
the wire
feeding assembly comprises a supporting wire guide and a wire feeder, wherein
the supporting
wire guide accepts the at least one wire from the wire feeder and directs the
at least one wire
towards the support, or the deposited portion of the 3D object. In some
embodiments, the
supporting wire guide is in contact with the wire feeder. In some embodiments,
the one or more
sensors comprise one or more strain gauges.
[0009] In some embodiments, prior to (a), the one or more sensors is
calibrated. In some
embodiments, (b) comprises measuring the reaction force in isolation from an
upstream tension
of the at least one wire. In some embodiments, the first portion of the at
least one wire is directed
using a print head, and wherein (b) comprises (i) determining an applied force
applied by a
gantry to the print head, and (ii) removing a weight of one or more printing
components from the
applied force to determine the reaction force. In some embodiments, the one or
more printing
components is selected from the group consisting of sensor, frame system,
mount plate, drive
motor, driver roller, preload motor, and preload roller. In some embodiments,
the method for
printing at least a portion of a 3D object further comprises, prior to (a),
selecting the at least one
parameter. In some embodiments, the support is a platform. In some
embodiments, the support is
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a previously deposited portion of the 3D object. In some embodiments, the
support is a sacrificial
obj ect.
[0010] In another aspect, the present disclosure provides a system for
printing at least a
portion of a three-dimensional (3D) object adjacent to a support or a
deposited portion of the 3D
object, comprising: a support configured to hold the at least the portion of
the 3D object; a
source configured to hold at least one wire, which at least one wire is usable
for the printing of
the at least the portion of the 3D object; one or more sensors configured to
generate a signal(s)
indicative of a reaction force of the support, or the deposited portion of the
3D object, against the
at least one wire; a power supply configured to flow electrical current
through the at least one
wire and the support, or the deposited portion of the 3D object; and a
controller operatively
coupled to the power supply, wherein the controller is configured to: i.
direct a first portion of
the at least one wire toward and in contact with the support, or the deposited
portion of the 3D
object, in accordance with at least one parameter; ii. upon contacting the at
least one wire with
the support, or the deposited portion of the 3D object, receive the signal(s)
from the one or more
sensors indicative of the reaction force exerted by the support, or the
deposited portion of the 3D
object, against the first portion of the at least one wire to provide a
measured value; iii. adjust the
at least one parameter in response to the measured value to provide at least
one adjusted
parameter; and iv. direct a second portion of the at least one wire toward and
in contact with the
support, or the deposited portion of the 3D object, in accordance with the at
least one adjusted
parameter.
[0011] In some embodiments, the system for printing at least a portion of a
3D object further
comprises a wire feeding assembly comprising a supporting wire guide and a
wire feeder,
wherein the supporting wire guide accepts the at least one wire from the wire
feeder and directs
the at least one wire towards the support, or the deposited portion of the 3D
object. In some
embodiments, the one or more sensors are kinematically mounted to hold the
wire feeding
assembly. In some embodiments, the supporting wire guide is in contact with
the wire feeder. In
some embodiments, the one or more sensors comprise one or more strain gauges.
In some
embodiments, the controller is configured to direct flow of electrical current
through the second
portion of the at least one wire and into the support or the deposited portion
of the 3D object, or
vice versa, to subject the second portion of the at least one wire to heating,
which heating is
sufficient to melt the second portion of the at least one wire. In some
embodiments, the
controller is configured to direct the second portion of the at least one wire
to be deposited on the
support or the deposited portion of the 3D object, thereby forming the at
least the portion of the
3D object.
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[0012] In some embodiments, the controller is configured to measure the
reaction force of
the at least one wire in isolation of an upstream tension of the at least one
wire. In some
embodiments, the controller is configured to adjust the at least one parameter
when the reaction
force exceeds a threshold value. In some embodiments, the support is a
platform. In some
embodiments, the support is a previously deposited portion of the 3D object.
In some
embodiments, the support is a sacrificial object.
[0013] In another aspect, the present disclosure provides a method for
printing at least a
portion of a three-dimensional (3D) object adjacent to a support, comprising:
(a) directing a first
portion of at least one wire toward and in contact with the support in
accordance with at least one
parameter; (b) upon contacting the at least one wire with the support, using
one or more sensors
to generate a signal(s) indicative of a reaction force exerted by the support
against the at least the
one wire, to provide a measured value; adjusting the at least one parameter in
response to the
measured value of the reaction force to provide at least one adjusted
parameter; and bringing a
second portion of the at least one wire toward and in contact with the support
in accordance with
the at least one adjusted parameter.
[0014] In some embodiments, the at least one parameter is adjusted when the
reaction force
exceeds a threshold value. In some embodiments, the method for printing at
least a portion of the
3D object further comprises subjecting the second portion of the at least one
wire to heating
upon flow of electrical current through the at least one wire and into the
support, or vice versa,
which heating is sufficient to melt the second portion of the at least one
wire. In some
embodiments, the method for printing at least a portion of the 3D object
further comprises
depositing the second portion of the at least one wire on the support, thereby
forming the at least
the portion of the 3D object. In some embodiments, the first portion of the at
least one wire is
directed through a wire feeding assembly. In some embodiments, the at least
one parameter is
selected from the group consisting of a wire feed speed, distance between a
tip of the at least one
wire and the support, distance between the tip of the at least one wire and
the at least the portion
of the 3D object, amount of power applied to the wire feeding assembly, amount
of current
applied to the wire feeding assembly, and amount of voltage applied to the
wire feeding
assembly. In some embodiments, the one or more sensors are kinematically
mounted to hold the
wire feeding assembly. In some embodiments, the wire feeding assembly
comprises a supporting
wire guide and a wire feeder. In some embodiments, the supporting wire guide
accepts the at
least one wire from the wire feeder and directs the at least one wire towards
the support. In some
embodiments, the supporting wire guide is in contact with the wire feeder. In
some
embodiments, the one or more sensors comprise one or more strain gauges.
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[0015] In some embodiments, prior to directing a first portion of at least
one wire toward and
in contact with the support, one or more sensors is calibrated. In some
embodiments, the reaction
force is measured in isolation from an upstream tension of the wire. In some
embodiments, the
first portion of the at least one wire is directed using a print head, and
wherein generating a
signal indicative of a reaction force exerted by the support comprises (i)
determining an applied
force applied by a gantry to the print head, and (ii) removing a weight of one
or more printing
components from the applied force to determine the reaction force. In some
embodiments, the
one or more printing components is selected from the group consisting of
sensor, frame system,
mount plate, drive motor, driver roller, preload motor, and preload roller. In
some embodiments,
the method for printing at least a portion of the 3D object further comprises
prior to directing a
first portion of at least one wire toward and in contact with the support,
selecting the at least one
parameter.
[0016] In another aspect of the present disclosure provides a system for
printing at least a
portion of the 3D object adjacent to a support, comprising: a support
configured to hold the at
least the portion of the 3D object; a source configured to hold at least one
wire, which wire is
usable for the printing of the at least the portion of the 3D object; one or
more sensors configured
to generate a signal(s) indicative of a reaction force of the support against
the at least one wire; a
power supply configured to flow electrical current through the at least one
wire and the support;
and a controller operatively coupled to the power supply. In some embodiments,
the controller is
configured to: (i) direct a first portion of the at least one wire toward and
in contact with the
support in accordance with at least one parameter; (ii) upon contacting the at
least one wire with
the support, receive the signal(s) from the one or more sensors indicative of
the reaction force
exerted by the support against the first portion of the at least one wire to
provide a measured
value; (iii) adjust the at least one parameter in response to the measured
value to provide at least
one adjusted parameter; (iv) direct a second portion of the at least one wire
toward and in contact
with the support in accordance with the at least one adjusted parameter.
[0017] In some embodiments, the system for printing at least a portion of
the 3D object,
further comprises a wire feeding assembly comprising a supporting wire guide
and a wire feeder.
In some embodiments, the supporting wire guide accepts the at least one wire
from the wire
feeder and directs the at least one wire towards the support. In some
embodiments, the one or
more sensors are kinematically mounted to hold the wire feeding assembly. In
some
embodiments, the supporting wire guide is in contact with the wire feeder. In
some
embodiments, the one or more sensors comprise one or more strain gauges. In
some
embodiments, the controller is configured to direct flow of electrical current
through the second
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portion of the at least one wire and into the support, or vice versa, to
subject the second portion
of the at least one wire to heating, which heating is sufficient to melt the
second portion of the at
least one wire. In some embodiments, the controller is configured to direct
the second portion of
the at least one wire to be deposited on the support, thereby forming the at
least the portion of the
3D object. In some embodiments, the controller is configured to measure the
reaction force of
the at least one wire in isolation of an upstream tension of the at least one
wire. In some
embodiments, the controller is configured to adjust the at least one parameter
when the reaction
force exceeds a threshold value.
[0018] Another aspect of the present disclosure provides a non-transitory
computer readable
medium comprising machine executable code that, upon execution by one or more
computer
processors, implements any of the methods above or elsewhere herein.
[0019] Another aspect of the present disclosure provides a system
comprising one or more
computer processors and computer memory coupled thereto. The computer memory
comprises
machine executable code that, upon execution by the one or more computer
processors,
implements any of the methods above or elsewhere herein.
[0020] Additional aspects and advantages of the present disclosure will
become readily
apparent to those skilled in this art from the following detailed description,
wherein only
illustrative embodiments of the present disclosure are shown and described. As
will be realized,
the present disclosure is capable of other and different embodiments, and its
several details are
capable of modifications in various obvious respects, all without departing
from the disclosure.
Accordingly, the drawings and description are to be regarded as illustrative
in nature, and not as
restrictive.
INCORPORATION BY REFERENCE
[0021] All publications, patents, and patent applications mentioned in this
specification are
herein incorporated by reference to the same extent as if each individual
publication, patent, or
patent application was specifically and individually indicated to be
incorporated by reference.
To the extent publications and patents or patent applications incorporated by
reference contradict
the disclosure contained in the specification, the specification is intended
to supersede and/or
take precedence over any such contradictory material.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The novel features of the invention are set forth with particularity
in the appended
claims. A better understanding of the features and advantages of the present
invention will be
obtained by reference to the following detailed description that sets forth
illustrative
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embodiments, in which the principles of the invention are utilized, and the
accompanying
drawings (also "Figure" and "FIG." herein), of which:
[0023] FIG. 1 schematically illustrates a force diagram of a wire feeder
and the various
forces acting on the wire as the wire is fed through a roller and preload
configuration;
[0024] FIG. 2 illustrates an example sensor assembly comprising the wire
feeding assembly;
[0025] FIG. 3 is a representation of the mass, spring, damper model;
[0026] FIG. 4 schematically illustrates a step response of the strain gauge
force reading;
[0027] FIG. 5 schematically illustrates a graph used in response
optimization from tuning of
mass, spring, and damper parameters;
[0028] FIG. 6 schematically illustrates a theorized optimized step
response;
[0029] FIG. 7 shows a computer system that is programmed or otherwise
configured to
implement methods provided herein;
[0030] FIG. 8 illustrates individual and sum calibration for a group of
sensors for a series of
loads;
[0031] FIG. 9 illustrates a second calibration using the wire back force
mechanism on the
printer;
[0032] FIG. 10 illustrates a system response while a feeder motor was
powered but
stationary and a hammer was used to hit the wire tip into the contact tip;
[0033] FIG. 11 shows measurements for the wire feeder driving wire, the
sensor noise, and
measurements of a friction load applied to the wire;
[0034] FIG. 12 shows measurements for the wire feeder driving wire and the
sensor noise
when a wire is freely driven;
[0035] FIG. 13 shows test data from printing a line while changing the
extrusion ratio;
[0036] FIG. 14 illustrates the result of the test print, lined up with the
data in FIG. 13;
[0037] FIG. 15 shows test data when printing corner turns;
[0038] FIG. 16 shows the amount of force read by the sensors when the wire
is pushed with
a specified feed length into a solid piece of metal;
[0039] FIG. 17 shows a focused view of the region between 4 and 5 on the x-
axis of FIG.
16;
[0040] FIG. 18 illustrates the signal from the process of filling a hole
when repairing a
portion of the 3D object; and
[0041] FIG. 19 schematically illustrates an example of a wire feeding
method.
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DETAILED DESCRIPTION
[0042] While various embodiments of the invention have been shown and
described herein,
it will be obvious to those skilled in the art that such embodiments are
provided by way of
example only. Numerous variations, changes, and substitutions may occur to
those skilled in the
art without departing from the invention. It should be understood that various
alternatives to the
embodiments of the invention described herein may be employed.
[0043] As used herein, the singular forms "a," "an," and "the" include
plural references
unless the context clearly dictates otherwise. Any reference to "or" herein is
intended to
encompass "and/or" unless otherwise stated.
[0044] The term "welding," as used herein, generally refers to a method of
heating at least a
portion of a feedstock (e.g., a metal wire) to form a pool of molten liquid
(e.g., molten metal) on
an object (e.g., a metal object). The pool of molten liquid may cool and
solidify on the object.
In some cases, the method may comprise heating the at least a portion of the
feedstock and at
least a portion of the object to form the pool of molten liquid.
[0045] The term "three-dimensional object" (also "3D object"), as used
herein, generally
refers to an object or a part that is printed by 3D printing. The 3D object
may be at least a
portion of a larger 3D object or an entirety of the 3D object.
[0046] The term "support," as used herein, generally refers to a structure
that supports a
nascent 3D object during printing and supports the 3D object after printing.
The support may be
a platform or an object that may not be a platform, such as another 3D object.
The other object
may be an object in need of repair or an object that is to be fused to another
object (e.g., by a
welding-type approach). The support may be a sacrificial object (e.g., one or
more sacrificial
layers) that may be removed from the 3D object after printing, or a previously
formed portion of
the 3D object, such as a previously formed (e.g., deposited) layer of the 3D
object.
[0047] The term "feedstock," as used herein, generally refers to a material
that is usable
alone or in combination with other material to print a 3D object. In some
examples, the
feedstock may be (i) a wire, ribbon or sheet, (ii) a plurality of wires,
ribbons or sheets, or (iii) a
combination of two or more of wires, ribbons and sheets (e.g., combination of
wires and
ribbons). The feedstock may comprise at least one of a polymer (e.g.,
thermoplastic), metal,
metal alloy, ceramic, or a combination thereof In an example, the feedstock
comprises a metal
or a combination of metals (e.g., a metal alloy). As another example, the
feedstock comprises a
metal and a polymer (e.g., as a composite). The 3D printing may be performed
with at least
about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more feedstocks. The 3D printing may
be performed with
less than or equal to about 10, 9, 8, 7, 6, 5, 4, 3, 2, or less feedstocks.
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[0048] The term "guide" generally refers to a component in a print head
that guides a
feedstock towards a location on which a 3D object is to be printed, such as
into a melt zone
adjacent to a support. The melt zone may be on a support or at least a portion
of a 3D object.
The guide may be a nozzle or a tip, for example. The guide may permit the
feedstock to pass
towards and in contact with the support. The guide may include an opening, and
during use, the
feedstock may be directed in contact with the guide through the opening and
towards the
support. As an alternative, the guide may not include an opening, but may
include a surface that
comes in contact with the feedstock. The feedstock may slide through, over or
under the guide
of the print head into the melt zone. The guide may make a sliding contact
with the feedstock
and conduct electrical current to or from the feedstock. The guide may
constrain the feedstock
radially. A position of the guide relative to the melt zone may be constrained
while the
feedstock is moving through the guide towards the melt zone.
[0049] In some cases, the term "guide" may generally refer to a component
in a welding gun
that guides a feedstock (e.g. a metal wire) towards a location on which
welding may occur. The
guide may be a nozzle, for example. The feedstock may be a welding electrode.
[0050] The term "roller", as used herein, generally refers to a part that
may be in contact
with a portion of a feedstock during printing. The roller may have various
shapes and sizes. The
roller may be circular, triangular, or square, for example. The roller may
have at least one
groove that is dimensioned to accommodate at least a portion of the feedstock.
The roller may
have at least one protrusion to come in contact with at least a portion of the
feedstock. The roller
may direct movement and/or direction of the feedstock during printing. The
roller may contact
and supply a force to the feedstock to maintain a tension on the feedstock
between a feedstock
source to the guide.
[0051] Whenever the term "at least," "greater than," or "greater than or equal
to" precedes the
first numerical value in a series of two or more numerical values, the term
"at least," "greater
than" or "greater than or equal to" applies to each of the numerical values in
that series of
numerical values. For example, greater than or equal to 1, 2, or 3 is
equivalent to greater than or
equal to 1, greater than or equal to 2, or greater than or equal to 3.
[0052] Whenever the term "at most", "no more than," "less than," or "less
than or equal to"
precedes the first numerical value in a series of two or more numerical
values, the term "no more
than," "less than," or "less than or equal to" applies to each of the
numerical values in that series
of numerical values. For example, less than or equal to 3, 2, or 1 is
equivalent to less than or
equal to 3, less than or equal to 2, or less than or equal to 1.
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[0053] The present disclosure provides methods and systems for forming a 3D
object. The
3D object may be based on a computer model of the 3D object, such as a
computer-aided design
(CAD) stored in a non-transitory computer storage medium (e.g., medium). As an
alternative,
the 3D object may not be based on any computer model. In such scenario,
methods and systems
of the present disclosure may be used to, for example, deposit material on
another object, couple
one object to at least another object (e.g., welding at least two objects
together), or cure a defect
in an object (e.g., fill a hole or other defect).
Printing Systems
[0054] In an aspect, the present disclosure provides a method for printing
at least a portion of
a three-dimensional (3D) object adjacent to a support. A first portion of at
least one wire may be
directed toward and in contact with the support using at least one parameter.
In other cases, prior
to directing a first portion of the wire to the support, at least one
parameter may be selected.
Upon contacting the at least one wire with the support, one or more sensors
may be used to
generate a signal(s) indicative of a reaction force exerted by the support
against the at least one
wire, to provide a measured value. The parameter may be adjusted in response
to the measured
value of the reaction force to provide an adjusted parameter. The measured
reaction force may
adjust the master or slave feeding system control, e.g. wire feed speed. The
speed adjustment and
control may be in real-time and may be continuous. In some cases, the
parameter may be
adjusted when the reaction force exceeds a threshold value to provide another
adjusted
parameter. Next, a second portion of the at least one wire may be brought
toward and in contact
with the support using the adjusted parameter.
[0055] The second portion of the at least one wire may be subjected to
heating upon flow of
electrical current through the at least one wire and into the support, or vice
versa. The heating
may be sufficient to melt the second portion of the at least one wire. The
second portion of the at
least one wire may be deposited on the support thereby forming at least a
portion of the 3D
object. The first portion of the wire may be directed through a wire feeding
assembly. The wire
feeding assembly may comprise a supporting wire guide tube and a wire feeder.
The supporting
wire guide may accept the wire from the wire feeder and direct the wire
towards the support. The
supporting wire guide tube may press against the wire feeder.
[0056] The reaction force or back-force measurement may be used as a
feedback to the
process control system. This control system may control the quality of the
print, and the reaction
force or back-force on the tip of the wire may be one of several key inputs to
the control system.
For example, if the back-force increases above a certain set point, the
control system can apply
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more power or slow down the motion system to accommodate. In some cases, the
force sensor
may be used to predict and prevent sparks, which can reduce the print quality.
[0057] The parameter may be a wire feed speed and/or amount of power and/or
current
and/or voltage applied to the wire feeding assembly. In some cases, the
parameter may be the
distance between the tip of the wire and the previously printed part or the
distance between the
wire guide and the support. In other cases, prior to directing the first
portion of the wire toward
and in contact with the support, the one or more sensors may be calibrated.
The calibration may
be one point calibration, two point calibration, or multipoint calibration.
[0058] In some cases, the wire back force or reaction force is measured in
isolation from the
upstream tension of the wire. The upstream tension in the wire may be removed
by the
supporting wire guide tube pressing on the wire feeder. The reaction force may
be measured by
isolating a force of friction through a wire guide tube from a force that a
feed hob imposes on the
at least one wire. The feed hob may comprise a preload and driver roller. In
some cases, the first
portion of the wire may be directed using a print head and measuring the
reaction force
comprises (i) determining an applied force applied by a gantry to the print
head and (ii)
removing a weight of one or more printing components from the applied force to
determine the
reaction force. The one or more printing components may be selected from the
group consisting
of sensor, frame system, mount plate, drive motor, driver roller, preload
motor, and preload
roller. The wire may be held by the preload and driver rollers. The force that
the wire exerts on
the sensor, e.g. load cells, may be determined. While holding the wire, the
sensors may comprise
static mass of various components, such as the motors and brackets. Without
considering the
static mass, the load cell reading may be isolated.
[0059] The sensor may be selected from the group consisting of force gauge,
load cell,
piezoelectric sensor, strain gauge, torque sensor, contact sensor, linear
variable differential, and
non-contact sensor. In some cases, the sensors may comprise one or more load
cells. The sensors
may be kinematically mounted to the wire feeding assembly. The one or more
load cells can be
hydraulic, pneumatic, or based on strain gauges. The one or more sensors may
be strain gauges.
There may be at least about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more sensors. In
other cases, there are
less than or equal about 10, 9, 8, 7, 6, 5, 4, 3, 2, or less sensors.
[0060] In some examples, the one or more sensors are attached to the wire
feeding assembly
in a manner such that the forces on each of the one or more sensors include
the force of gravity
and a reactionary force (e.g., as may be imparted upon a feedstock coming in
contact with
surface). This may advantageously permit the reactionary force to be isolated
from other forces
that may be imparted on each of the one or more sensors. Such kinematic
mounting may be
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achieved, for example, by attaching a sensor to a supporting platform that
also supports other
components of the wire feeding assembly.
[0061] FIG. 1 illustrates an example force diagram of a wire feeder 100,
showing various
forces acting on a wire 105 as the wire 105 is fed through a preload roller
120 and a driver roller
135 toward a support 140. The wire 105 may be fed using a parameter, e.g. wire
speed or amount
of power. A preload force 115 may be applied to the preload roller 120 to
press the wire 105 into
the driver roller 135, which applies a traction force 125 along the length of
the wire 105 to move
the wire 105. The driver roller 135 may comprise a drive torque 130 causing
its rotation. Upon
contact with the support 140, a reaction force 145 exerted by the support 140
against the wire
105 may be measured. In some cases, the traction force 125 applied on the wire
105 may be
equal to the upstream tension plus the downstream compression. The downstream
compression
may be the reaction force 145. The upstream tension may be the traction force
125. In other
cases, the reaction force 145 may be measured in isolation of the upstream
tension.
[0062] In another aspect, the present disclosure provides a system for
printing at least a
portion of the 3D object adjacent to a support. The system may comprise a
support configured to
hold at least the portion of the 3D object, a source configured to hold the at
least one wire, one or
more sensors configured to generate a signal(s) indicative of a reaction force
of the support
against the at least one wire, and a power supply configured to electrical
current through the wire
and the support. The wire may be used for printing of at least a portion of
the 3D object.
Furthermore, a controller may be operatively coupled to the power supply. The
controller may be
configured to (i) direct a first portion of the at least one wire toward and
in contact with the
support in accordance with at least one parameter; (ii) upon contacting at
least one wire with the
support, receive the signal(s) from the one or more sensors indicative of the
reaction force
exerted by the support against the first portion of the at least one wire to
provide a measured
value; (iii) adjust the at least one parameter in response to the measured
value to provide at least
one adjusted parameter; (iv) direct a second portion of the at least one wire
toward and in contact
with the support in accordance with the at least one adjusted parameter. In
some cases, the
controller may be configured to adjust the parameter when the reaction force
exceeds a threshold
value.
[0063] The threshold may be a pre-determined threshold value or range of
the force. The
threshold may be a force acceptable by the wire without experiencing
significant damage (e.g.,
deformation or cut). The threshold may be a force acceptable by the support
without
experiencing a significant damage (e.g., deformation or cut). The threshold
may be specific for a
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type of material the wire is made of Alternatively or in addition to, the
threshold may be a
common threshold for different types of materials that different wires are
made of.
[0064] FIG. 2 illustrates an example of a sensor assembly 200 comprising a
wire 205, a wire
guide 210, a mount 215, load cells 220, a wire feeding assembly 225, a preload
roller 230 and a
driver roller 235. The wire guide 210 may be for directing the wire 205
towards a support 240.
The at least one wire guide 210 may include a tube for guiding the wire 205.
The support 240
may include a melting zone 245, which may be formed, for example, upon the
flow of electrical
current through the wire 205 and into the support 240, or vice versa. The wire
205 may be
driven toward the support 240 using a preload roller 230 and a driver roller
235. The wire guide
201 can press against the wire feeding assembly 225. The wire 205 may comprise
a tip end that
comes in contact with the support 240. As the wire feeding assembly 225
directs the wire 205
into the melt zone 245, the load cell sensors 220 can sense a reactionary
force generated upon the
wire 205 coming in contact with the support 240. The load cells 220 may be
attached to the
mount plate 215. The load cells 220 may be positioned symmetrically from the
wire guide 210,
and each of the load cells 220 can detect an equal amount of force. The load
cells 220 may be
kinematically mounted to the wire feeding assembly 225, such as through
attachment to the
mount plate 215. The mount plate 215 in turn can support the preload roller
230 and the driver
roller 235. In some cases, weight is minimized so that the mount plate 215
supports components
of the wire feeding assembly 225, such as the preload roller 230 and the
driver roller 235. As a
result, weights (or forces upon) other components (e.g., the wire guide 210)
may not be
measured or off set by the load cells 220. The signal to noise ratio may be
used as an indicator of
how well the sensor assembly is operating.
[0065] The preload roller 230 may include a motor for rotating the preload
roller 230. As an
alternative or in addition to, the driver roller 235 may include a motor for
rotating the driver
roller 235.
[0066] In some cases, the controller is configured to direct flow of
electrical current through
the second portion of the wire and into the support, or vice versa, to subject
the second portion of
the at least one wire to heating, which heating is sufficient to melt the
second portion of the wire.
For example, the controller can direct a power supply to flow electrical
current through the wire
and into the support, or vice versa. This may subject the wire to heating
(e.g., Joule heating),
which may be sufficient to melt the second portion. The controller may be
configured to direct
the second portion of the wire to be deposited on the support, thereby forming
at least a portion
of the 3D object.
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[0067] A traction force may be required to direct the feedstock towards the
guide. Thus, the
gap between the driver roller and the preload roller may be sufficiently small
so that the
feedstock is (i) in contact with the two rollers and (ii) compressed between
the two rollers. The
force, e.g. a normal force, due to compression and the friction between the
feedstock and the
driver roller may produce the traction force at one or more contact surfaces
between the
feedstock and the driver roller. The traction force may be a contact force.
The traction force in
combination with the rotation of the driver roller may be sufficient to direct
movement of the
feedstock towards or away from the guide.
[0068] In some cases, the wire back force or reaction force is measured in
isolation from the
upstream tension of the wire. The upstream tension in the wire may be removed
by the
supporting wire guide tube pressing on the wire feeder. The wire back force or
reaction force can
be measured through a variety of approaches and with different types of
sensors, such as
kinematically mounted strain gauges that support the wire feeding mechanism.
The sensor may
be selected from the group consisting of force gauge, load cell, piezoelectric
sensor, strain gauge,
torque sensor, contact sensor, linear variable differential, and non-contact
sensor. When force is
applied to the tip of the wire, the wire back force mechanism (WFS) can sense
the reaction force
of the wire on the wire feeder. In some cases, there may be three sensors
assembled in a
kinematic fashion that hold the wire feeding mechanism. In other cases, there
is at least about 1,
2, 3, 4, 5, 6, 7, 8, 9, 10, or more sensors. Alternatively, there may be less
than or equal about 10,
9, 8, 7, 6, 5, 4, 3, 2, or less sensors.
[0069] The system may comprise a feedstock source configured to hold a
feedstock. The
feedstock may be usable for printing the 3D object. The system may comprise a
print head
comprising a guide. The guide may direct the feedstock from the feedstock
source towards and
in contact with a support or at least a portion of the 3D object adjacent to
the support. The guide
may also direct the feedstock in a direction away from the guide towards the
feedstock source.
The system may comprise a driver roller configured to come in contact with the
feedstock. The
driver roller may be coupled to an actuator that subjects the driver roller to
rotation to direct the
feedstock towards the guide. The system may comprise a preload roller adjacent
to the driver
roller. The preload roller may be configured to come in contact with the
feedstock at a position
adjacent to the driver roller. The preload roller and the driver roller may be
separated by a gap.
A size of the gap may be adjustable to permit the feedstock to be directed
through the gap. The
system may comprise a power source in electrical communication with the
feedstock and the
support. The power source may be configured to supply electrical current from
the guide
through the feedstock and to the support, or vice versa, during printing the
at least a portion of
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the 3D object. The system may also comprise a controller in electrical
communication with the
power source. The controller may be configured to direct adjustment of the
size of the gap. The
controller may be configured to direct the actuator coupled to the driver
roller to direct the
feedstock through the gap and towards the guide. The controller may be
configured to direct the
power source to supply the electrical current from the guide through the
feedstock and to the
support, or vice versa, during printing under conditions sufficient to melt
the feedstock when the
feedstock is in contact with the support or the portion of the 3D object.
[0070] The print head may move relative to the support. The print head may
further
comprise a mechanical gantry capable of motion in one or more axes of control
(e.g., one or
more of the XYZ planes or rotational axes) via one or more actuators. In some
cases, the
mechanical gantry may be capable of motion in 6-axis of control. Many
actuators may
accomplish the required motion, including electric, hydraulic or pneumatic
motors, linear
actuators, belts, pulleys, lead screws, and other devices. The one or more
actuators of the print
head may be operatively connected to the controller. The controller may direct
movement of the
print head during printing the at least the portion of the 3D object. In some
examples, the system
may comprise a plurality of assemblies. The system may include at least about
1, 2, 3, 4, 5, 6, 7,
8, 9, 10, or more assemblies. The system may include less than or equal about
10, 9, 8, 7, 6, 5, 4,
3, 2, or less assemblies.
[0071] The assembly may be a pusher assembly (a "slave" assembly) that
pushes the
feedstock from the feedstock source towards to guide. In some cases, the
system may include a
plurality of the assembly for each feedstock source of a plurality of
feedstock sources.
Alternatively or in addition to, the system may include an additional assembly
adjacent to the
guide. The additional assembly may be a puller assembly (a "master" assembly)
that pulls the
feedstock into the guide. The first roller of the assembly may have a groove
to accept at least a
portion of the feedstock. The first roller may include at least one additional
groove adjacent to
the groove. The at least one additional groove may be arranged in a parallel
fashion to the
groove. The at least one additional groove may accept at least a portion of at
least one additional
feedstock. The groove and the at least one additional groove may have
different dimensions
(e.g., widths, depths, etc.) and/or geometries. The first roller may include
at least about 1, 2, 3,
4, 5, 6, 7, 8, 9, 10, or more grooves. The first roller may include less than
or equal about 10, 9, 8,
7, 6, 5, 4, 3, 2, or less assemblies.
[0072] The first roller comprising the at least one additional groove may
be coupled (e.g.,
mechanically attached) to a position adjusting mechanism. The position
adjusting mechanism
may move the first roller into and out of alignment with the feedstock or the
at least one
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additional feedstock. The position adjusting mechanism may be one or more
actuators (e.g., one
or more linear screw actuators). The position adjusting mechanism may be a
manual user
operation or the controller automated process. In some cases, the controller
may be in
communication with the position adjusting mechanism to direct the position
adjusting
mechanism to move the first roller during the alignment with the feedstock or
the at least one
additional feedstock. In some examples, the position adjusting mechanism
comprises a stage for
holding at least the driver roller. The stage may further have one or more
linear actuators that
are mechanically attached to the stage.
[0073] In some cases, the first roller with the groove may be a driver
roller that is coupled to
an actuator that subjects the driver roller to rotate and direct the feedstock
towards the guide.
The second roller, with or without the protrusion, may be a preload roller
that presses at least a
portion of the feedstock towards the driver roller. In some cases, the second
roller, with or
without the protrusion, may be a driver roller that is coupled to an actuator
that subjects the
driver roller to rotate and direct the feedstock towards the guide. The first
roller with the groove
may be a preload roller that presses at least a portion of the feedstock
towards the driver roller.
[0074] The actuator may be a rotational actuator or an electric motor. A
rotation may feed
the feedstock along a direction away from the feedstock source towards the
guide. Alternatively
or in addition to, the rotation may direct the feedstock along a direction
away from the guide
towards the feedstock source. The actuator may rotate the driver roller at a
plurality of rotating
speeds. The actuator may be configured to accelerate, decelerate, maintain at
a given speed of
the plurality of rotating speeds, or control a direction of rotation of the
driver roller. The actuator
may be in communication with the controller. The controller may direct the
actuator to rotate the
driver roller. In some cases, the actuator of the driver roller may comprise
an encoder. The
controller may be operatively coupled to the encoder of the actuator of the
driver roller to
monitor operating velocities of the driver roller.
[0075] The system may comprise one or a plurality of driver rollers. The
system may
include at least about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more driver rollers.
The system may include
less than or equal about 10, 9, 8, 7, 6, 5, 4, 3, 2, or less driver rollers.
Each driver roller may be
independently coupled to an actuator (e.g., motor) for subjecting a rotational
movement, and
each actuator may be independently or collectively in communication with one
or more
controllers. As an alternative, at least some of the driver rollers may be
coupled to the same
actuator.
[0076] The preload roller may be configured to (i) come in contact with at
least a portion of
the feedstock at a position adjacent to the driver roller and (ii) direct the
at least the portion of the
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feedstock towards the driver roller. The preload roller may comprise an outer
shell and an inner
shell. The outer shell and the inner shell may move independently from each
other. An outer
circumference of the outer shell may come in contact with the portion of the
wire. The preload
roller may further comprise a bearing assembly disposed between the outer
shell and the inner
shell. The bearing assembly may facilitate the rotational motion of the outer
shell with respect to
the inner shell during directing the portion of the feedstock towards or away
from the guide. The
bearing assembly may facilitate the outer shell to roll with very little
rolling resistance. A rolling
element in the bearing assembly may be a ball bearing, a roller bearing, a
gear bearing, etc. The
bearing assembly may be lubricated with a viscous lubricant to facilitate the
rotational motion of
the outer shell of the preload roller. The viscous lubricant may remain inside
the bearing
assembly.
[0077] The system may comprise one or a plurality of preload rollers. In
some cases, the
preload roller may be coupled to an actuator. In other cases, the preload
roller may not be
coupled to an actuator but may spin upon movement of the wire. The system may
include at least
about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more preload rollers. The system may
include less than or
equal about 10, 9, 8, 7, 6, 5, 4, 3, 2, or less preload rollers.
[0078] The 3D printing may be performed with at least about 1, 2, 3, 4, 5,
6, 7, 8, 9, 10, or
more feedstocks. The 3D printing may be performed with less than or equal
about 10, 9, 8, 7, 6,
5, 4, 3, 2, or less feedstocks. In some cases, a plurality of feedstocks may
be used to print a layer
of the 3D object. The feedstock may be (i) a wire, ribbon or sheet, (ii) a
plurality of wires,
ribbons or sheets, or (iii) a combination of two or more of wires, ribbons and
sheets (e.g.,
combination of wires and ribbons). The feedstock may have other form factors.
If multiple
feedstocks are used, the multiple feedstocks may be brought together to the
opening.
Alternatively or in addition to, at least some or each of the multiple
feedstocks may be directed
to the opening or different openings. A cross-sectional diameter of the feed
stock may be at least
about 0.01 millimeters (mm), 0.02 mm, 0.03 mm, 0.04 mm, 0.05 mm, 0.06 mm, 0.07
mm, 0.08
mm, 0.09 mm, 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45
mm, 0.5
mm, 1.0 mm, 1.5 mm, 2.0 mm, 2.5 mm, 3.0 mm, 3.5 mm, 4.0 mm, 5 mm, 6 mm, 7 mm,
8 mm, 9
mm, 10 mm or more. Alternatively, the cross-sectional diameter may be less
than or equal to
about 10 mm, 9 mm, 8 mm, 7 mm, 6 mm, 5 mm, 4.0 mm, 3.5 mm, 3.0 mm, 2.5 mm, 2.0
mm, 1.5
mm, 1.0 mm, 0.5 mm, 0.45 mm, 0.4 mm, 0.35 mm, 0.3 mm, 0.25 mm, 0.2 mm, 0.15
mm, 0.1
mm, 0.09 mm, 0.08 mm, 0.07 mm, 0.06 mm, 0.05 mm, 0.04 mm, 0.03 mm, 0.02 mm,
0.01 mm
or less.
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[0079] The feedstock receiver may be a guide (e.g., a nozzle) of a welding
gun for welding
(e.g., gas metal arc welding, flux-cored arc welding, etc.). The feedstock
receiver may be a
guide (e.g. a nozzle) of a printing head in a device for printing a 3D object.
The feedstock may
be usable for printing the 3D object. The feedstock may be formed of at least
one metal. In
some examples, the feedstock comprises one or more metals selected from the
group consisting
of steel, stainless steel, iron, copper, gold, silver, cobalt, chromium,
nickel, titanium, platinum,
palladium, titanium, and aluminum. The feedstock may include at least one non-
metal, such as a
fiber material (e.g., elemental fiber or nanotube) and/or polymeric material.
The fiber material
may include, for example, carbon fiber, carbon nanotubes, and/or graphene.
Alternatively, the
feedstock may include at least one natural or synthetic ceramic material. The
natural or synthetic
ceramic material may be calcium phosphate, calcium carbonate, or silicate.
[0080] The feedstock may comprise at least one of polymers, metals, metal
alloys, ceramics,
or mixtures thereof. In some cases, the polymers may be thermoplastics.
Examples of
thermoplastics include acrylate or methylmethacrylate polymers or copolymers
(e.g.,
polyacrylates, polymethylmethacrylates, etc.); polylactic acid (PLA) polymers;
polyhydroxyalkanoate (PHA) polymers (e.g., polyhydroxybutyrate (PHB));
polycaprolactone
(PCL) polymers; polyglycolic acid polymers; acrylonitrile-butadiene-styrene
polymers (ABS);
polyvinylidene fluoride polymers; polyurethane polymers; polyolefin polymers
(e.g.,
polyethylene, polypropylene, etc.); polyester polymers; polyalkylene oxide
polymers (e.g.,
polyethylene oxide (PEO)); polyvinyl alcohol (PVA) polymers; polyamide
polymers;
polycarbonate polymers; high impact polystyrene (HIPS) polymers; polyurethane
polymers, or
mixtures thereof.
[0081] Segments (e.g. particles) of the feedstock may be printed on the
support by melting a
tip of the feedstock with an electric current. The electric current may flow
from the guide of the
print head through the feedstock and to the support, or vice versa. When the
tip of the feedstock
is in contact with the support, an electric circuit comprising the guide of
the print head, the
feedstock, the support, and a power source may be formed. The controller may
be operatively
coupled to the power source. In such electric circuit, the feedstock may be a
first electrode, and
the support may be a second electrode. If the feedstock is in physical contact
with the support
and the power source supplies the electrical current from the guide through
the feedstock and to
the support, or vice versa, the feedstock and the support are in electrical
contact. In the electrical
contact, there may be an electrical resistance between the feedstock and the
support (i.e., contact
resistance) due to a small surface area of the feedstock and microscopic
imperfections on a
surface of the tip of the feedstock and/or a surface of the support. The
contact resistance
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between the tip of the feedstock and the support may heat a local area at the
contact according to
Equation 1 (i.e., Joule's First Law):
Q = 12 = R = t (Equantion 1)
where Q is the heat generated at the local area at the contact,
/ is the electric current,
R is the contact resistance between the feedstock and the support, and
t is a duration of an application of the current.
[0082] The
heat generated at the local area at the contact between the feedstock and the
support may be sufficient to melt the tip of the feedstock into a segment and
to fuse the segment
to the support. The heat may be generated by resistive heating (e.g., Joule
heating). In some
examples, the segment is a strand or a particle. The strand or particle may be
molten. Upon
deposition of the segment on the support, the segment may act as a second
electrode in the
electric circuit to melt and print additional segments of the feedstock. The
heat generated at the
local area may be sufficient to melt the tip of the feedstock into a segment
and to fuse the
segment to a segment on the support. The heat generated at the local area may
be sufficient to
melt the tip of the feedstock into a segment and to fuse the segment to one or
more neighboring
segments. As such, segments of the feedstock may be deposited without use or
generation of
electric arcs and/or plasma, but rather by utilizing energy (e.g., electrical
energy) within the
feedstock. The energy within the feedstock may be to (i) melt at least a
portion of the feedstock
and (ii) print and/or repair at least a portion of the 3D object.
[0083] The tip of the feedstock may melt while the feedstock is in contact
with the support and
the feedstock and the support are moving relative to one another. For example,
the feedstock is
moving and the support is stationary. As another example, the feedstock is
stationary and the
support is moving (e.g., along a plane orthogonal to a longitudinal axis of
the support
perpendicular to the support). As another example, both the feedstock and the
support are
moving (e.g., along a plane orthogonal to a longitudinal axis of the support
perpendicular to the
support).
[0084] The
support may be a printing platform. As an alternative, the support may be a
previously deposited portion (e.g., previously deposited layer), such as a
previously deposited
layer of the three-dimensional object or a previously deposited sacrificial
layer(s). The support
may be a sacrificial object (e.g., one or more sacrificial layers). As another
alternative, the
support may be a part (e.g., part formed by 3D printing or other approaches)
and the feedstock
may be deposited on the part.
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[0085] The heat generated at a point of contact between the feedstock
(e.g., a wire) and the
support may be such that the feedstock and/or the melt generated from the
feedstock has a
temperature of at least about 100 degrees Celsius ( C), 200 C, 300 C, 400
C, 500 C, 600 C,
700 C, 800 C, 900 C, 1000 C, 1100 C, 1200 C, 1300 C, 1400 C, 1500 C,
1600 C, 1700
C, 1800 C, 1900 C, 2000 C, 2100 C, 2200 C, 2300 C, 2400 C, 2500 C,
2600 C, 2700
C, 2800 C, 2900 C, 3000 C, 3100 C, 3200 C, 3300 C, 3400 C, 3500 C,
3600 C, 3700
C, 3800 C, 3900 C, 4000 C, 5000 C or more. The temperature may be at most
about 5000
C, 4000 C, 3900 C, 3800 C, 3700 C, 3600 C, 3500 C, 3400 C, 3300 C,
3200 C, 3100
C, 3000 C, 2900 C, 2800 C, 2700 C, 2600 C, 2500 C, 2400 C, 2300 C,
2200 C, 2100
C, 2000 C, 1900 C, 1800 C, 1700 C, 1600 C, 1500 C, 1400 C, 1300 C,
1200 C, 1100
C, 1000 C, 900 C, 800 C, 700 C, 600 C, 500 C, 400 C, 300 C, 200 C,
100 C, or less.
[0086] In some examples, the temperature may be at least about 400 C, 410
C, 420 C,
430 C, 440 C, 450 C, 460 C, 470 C, 480 C, 490 C, 500 C, 510 C, 520
C, 530 C, 540
C, 550 C, 560 C, 570 C, 580 C, 590 C, 600 C, 610 C, 620 C, 630 C, 640
C, 650 C,
660 C, 670 C, 680 C, 690 C, 700 C, 710 C, 720 C, 730 C, 740 C, 750
C, 760 C, 770
C, 780 C, 790 C, 800 C, 810 C, 820 C, 830 C, 840 C, 850 C, 860 C, 870
C, 880 C,
890 C, 900 C, 910 C, 920 C, 930 C, 940 C, 950 C, 960 C, 970 C, 980
C, 990 C, 1000
C, 1110 C, 1120 C, 1130 C, 1140 C, 1150 C, 1160 C, 1170 C, 1180 C, 1190 C,
1200
C, 1210 C, 1220 C, 1230 C, 1240 C, 1250 C, 1260 C, 1270 C, 1280 C,
1290 C, 1300
C, or more when the feedstock comprises aluminum or alloys. The temperature
may be at most
about 1300 C, 1290 C, 1280 C, 1270 C, 1260 C, 1250 C, 1240 C, 1230 C,
1220 C, 1210
C, 1200 C, 1190 C, 1180 C, 1170 C, 1160 C, 1150 C, 1140 C, 1130 C, 1120 C,
1110
C, 1100 C, 1090 C, 1080 C, 1070 C, 1060 C, 1050 C, 1040 C, 1030 C, 1020 C,
1010
C, 1000 C, 990 C, 980 C, 970 C, 960 C, 950 C, 940 C, 930 C, 920 C,
910 C, 900 C,
890 C, 880 C, 870 C, 860 C, 850 C, 840 C, 830 C, 820 C, 810 C, 800
C, 790 C, 780
C, 770 C, 760 C, 750 C, 740 C, 730 C, 720 C, 710 C, 700 C, 690 C, 680
C, 670 C,
660 C, 650 C, 640 C, 630 C, 620 C, 610 C, 600 C, 590 C, 580 C, 570
C, 560 C, 550
C, 540 C, 530 C, 520 C, 510 C, 500 C, 490 C, 580 C, 470 C, 460 C, 450
C, 440 C,
430 C, 420 C, 410 C, 400 C, or less when the feedstock comprises aluminum
or alloys.
[0087] In some examples, the temperature may be at least about 800 C, 810
C, 820 C,
830 C, 840 C, 850 C, 860 C, 870 C, 880 C, 890 C, 900 C, 910 C, 920
C, 930 C, 940
C, 950 C, 960 C, 970 C, 980 C, 990 C, 1000 C, 1010 C, 1020 C, 1030 C,
1040 C,
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1050 C, 1060 C, 100 C, 1080 C, 1090 C, 1100 C, 1110 C, 1120 C, 1130 C, 1140 C,
1150 C, 1160 C, 1170 C, 1180 C, 1190 C, 1200 C, 1210 C, 1220 C, 1230 C, 1240
C,
1250 C, 1260 C, 1270 C, 1280 C, 1290 C, 1300 C, 1310 C, 1320 C, 1330
C, 1340 C,
1350 C, 1360 C, 1370 C, 1380 C, 1390 C, 1400 C, 1410 C, 1420 C, 1430
C, 1440 C,
1450 C, 1460 C, 1470 C, 1480 C, 1490 C, 1500 C, 1510 C, 1520 C, 1530
C, 1540 C,
1550 C, 1560 C, 1570 C, 1580 C, 1590 C, 1600 C, or more when the
feedstock comprises
copper or alloys. The temperature may be at most about 1600 C, 1590 C, 1580
C, 1570 C,
1560 C, 1550 C, 1540 C, 1530 C, 1520 C, 1510 C, 1500 C, 1490 C, 1480
C, 1470 C,
1460 C, 1450 C, 1440 C, 1430 C, 1420 C, 1410 C, 1400 C, 1390 C, 1380
C, 1370 C,
1360 C, 1350 C, 1340 C, 1330 C, 1320 C, 1310 C, 1300 C, 1290 C, 1280
C, 1270 C,
1260 C, 1250 C, 1240 C, 1230 C, 1220 C, 1210 C, 1200 C, 1190 C, 1180 C, 1170
C,
1160 C, 1150 C, 1140 C, 1130 C, 1120 C, 1110 C, 1100 C, 1090 C, 1080 C, 1070
C,
1060 C, 1050 C, 1040 C, 1030 C, 1020 C, 1010 C, 1000 C, 990 C, 980 C,
970 C, 960
C, 950 C, 940 C, 930 C, 920 C, 910 C, 900 C, 890 C, 880 C, 870 C, 860
C, 850 C,
840 C, 830 C, 820 C, 810 C, 800 C, or less when the feedstock comprises
copper or alloys.
[0088] In some examples, the temperature may be at least about 800 C, 810
C, 820 C,
830 C, 840 C, 850 C, 860 C, 870 C, 880 C, 890 C, 900 C, 910 C, 920
C, 930 C, 940
C, 950 C, 960 C, 970 C, 980 C, 990 C, 1000 C, 1010 C, 1020 C, 1030 C,
1040 C,
1050 C, 1060 C, 1070 C, 1080 C, 1090 C, 1100 C, 1110 C, 1120 C, 1130 C, 1140
C,
1150 C, 1160 C, 1170 C, 1180 C, 1190 C, 1200 C, 1210 C, 1220 C, 1230 C, 1240
C,
1250 C, 1260 C, 1270 C, 1280 C, 1290 C, 1300 C, 1310 C, 1320 C, 1330
C, 1340 C,
1350 C, 1360 C, 1370 C, 1380 C, 1390 C, 1400 C, 1410 C, 1420 C, 1430
C, 1440 C,
1450 C, 1460 C, 1470 C, 1480 C, 1490 C, 1500 C, 1510 C, 1520 C, 1530
C, 1540 C,
1550 C, 1560 C, 1570 C, 1580 C, 1590 C, 1600 C, or more when the
feedstock comprises
gold or alloys. The temperature may be at most about 1600 C, 1590 C, 1580
C, 1570 C,
1560 C, 1550 C, 1540 C, 1530 C, 1520 C, 1510 C, 1500 C, 1490 C, 1480
C, 1470 C,
1460 C, 1450 C, 1440 C, 1430 C, 1420 C, 1410 C, 1400 C, 1390 C, 1380
C, 1370 C,
1360 C, 1350 C, 1340 C, 1330 C, 1320 C, 1310 C, 1300 C, 1290 C, 1280
C, 1270 C,
1260 C, 1250 C, 1240 C, 1230 C, 1220 C, 1210 C, 1200 C, 1190 C, 1180 C, 1170
C,
1160 C, 1150 C, 1140 C, 1130 C, 1120 C, 1110 C, 1100 C, 1090 C, 1080 C, 1070
C,
1060 C, 1050 C, 1040 C, 1030 C, 1020 C, 1010 C, 1000 C, 990 C, 980 C,
970 C, 960
C, 950 C, 940 C, 930 C, 920 C, 910 C, 900 C, 890 C, 880 C, 870 C, 860
C, 850 C,
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840 C, 830 C, 820 C, 810 C, 800 C, or less when the feedstock comprises
gold or alloys.
[0089] In some examples, the temperature may be at least about 810 C, 820
C, 830 C,
840 C, 850 C, 860 C, 870 C, 880 C, 890 C, 900 C, 910 C, 920 C, 930
C, 940 C, 950
C, 960 C, 970 C, 980 C, 990 C, 1000 C, 1050 C, 1100 C, 1150 C, 1200
C, 12050 C,
1300 C, 1350 C, 1400 C, 1450 C, 1500 C, 1550 C, 1600 C, 1650 C, 1700
C, 1750 C,
1800 C, 1850 C, 1900 C, 1950 C, 2000 C, 2050 C, 2100 C, 2150 C, 2200
C, 2250 C,
2300 C, 2350 C, 2400 C, 2450 C, 2500 C, or more when the feedstock
comprises iron or
alloys. The temperature may be at most about 2500 C, 2450 C, 2400 C, 2350
C, 2300 C,
2250 C, 2200 C, 2150 C, 2100 C, 2050 C, 2000 C, 1900 C, 1800 C, 1700
C, 1600 C,
1500 C, 1400 C, 1300 C, 1200 C, 1100 C, 1000 C, 990 C, 980 C, 970 C,
960 C, 950
C, 940 C, 930 C, 920 C, 910 C, 900 C, 890 C, 880 C, 870 C, 860 C, 850
C, 840 C,
830 C, 820 C, 810 C, 800 C, or less when the feedstock comprises iron or
alloys.
[0090] In some examples, the temperature may be at least about 1500 C,
1510 C, 1520 C,
1530 C, 1540 C, 1550 C, 1560 C, 1570 C, 1580 C, 1590 C, 1600 C, 1610
C, 1620 C,
1630 C, 1640 C, 1650 C, 1660 C, 1670 C, 1680 C, 1690 C, 1700 C, 1710
C, 1720 C,
1730 C, 1740 C, 1750 C, 1760 C, 1770 C, 1780 C, 1790 C, 1800 C, 1850
C, 1900 C,
1950 C, 2000 C, 2050 C, 2100 C, 2150 C, 2200 C, 2250 C, 2300 C, or
more when the
feedstock comprises platinum or alloys. The temperature may be at most about
2300 C,2250
C,2200 C,2150 C,2100 C, 2050 C,2000 C,1950 C,1900 C,1850 C,1800 C,
1790 C,
1780 C, 1770 C, 1760 C, 1750 C, 1740 C, 1730 C, 1720 C, 1710 C, 1700
C, 1690 C,
1680 C, 1670 C, 1660 C, 1650 C, 1640 C, 1630 C, 1620 C, 1610 C, 1600
C, 1590 C,
1580 C, 1570 C, 1560 C, 1550 C, 1540 C, 1530 C, 1520 C, 1510 C, 1500
C, or less
when the feedstock comprises platinum or alloys.
[0091] In some examples, the temperature may be at least about 1300 C,
1310 C, 1320 C,
1330 C, 1340 C, 1350 C, 1360 C, 1370 C, 1380 C, 1390 C, 1400 C, 1410
C, 1420 C,
1430 C, 1440 C, 1450 C, 1460 C, 1470 C, 1480 C, 1490 C, 1500 C, 1510
C, 1520 C,
1530 C, 1540 C, 1550 C, 1560 C, 1570 C, 1580 C, 1590 C, 1600 C, 1610
C, 1620 C,
1630 C, 1640 C, 1650 C, 1660 C, 1670 C, 1680 C, 1690 C, 1700 C, 1710
C, 1720 C,
1730 C, 1740 C, 1750 C, 1760 C, 1770 C, 1780 C, 1790 C, 1800 C, 1850
C, 1900 C,
1950 C, 2000 C, 2050 C, 2100 C, 2150 C, 2200 C, 2250 C, 2300 C, 2350
C, 2400 C,
or more when the feedstock comprises titanium or alloys. The temperature may
be at most about
2400 C, 2350 C, 2300 C, 2250 C, 2200 C, 2150 C, 2100 C, 2050 C,2000
C,1950
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C,1900 C,1850 C,1800 C, 1790 C, 1780 C, 1770 C, 1760 C, 1750 C, 1740
C, 1730 C,
1720 C, 1710 C, 1700 C, 1690 C, 1680 C, 1670 C, 1660 C, 1650 C, 1640
C, 1630 C,
1620 C, 1610 C, 1600 C, 1590 C, 1580 C, 1570 C, 1560 C, 1550 C, 1540
C, 1530 C,
1520 C, 1510 C, 1500 C, 1490 C, 1480 C, 1470 C, 1460 C, 1450 C, 1440
C, 1430 C,
1420 C, 1410 C, 1400 C, 1390 C, 1380 C, 1370 C, 1360 C, 1350 C, 1340
C, 1330 C,
1320 C, 1310 C, 1300 C, or less when the feedstock comprises titanium or
alloys.
[0092] In some examples, the temperature may be at least about 1200 C,
1210 C, 1220 C,
1230 C, 1240 C, 1250 C, 1260 C, 1270 C, 1280 C, 1290 C, 1300 C, 1310
C, 1320 C,
1330 C, 1340 C, 1350 C, 1360 C, 1370 C, 1380 C, 1390 C, 1400 C, 1410
C, 1420 C,
1430 C, 1440 C, 1450 C, 1460 C, 1470 C, 1480 C, 1490 C, 1500 C, 1510
C, 1520 C,
1530 C, 1540 C, 1550 C, 1560 C, 1570 C, 1580 C, 1590 C, 1600 C, 1650
C, 1700 C,
1750 C, 1800 C, 1850 C, 1900 C, 1950 C, 2000 C, 2050 C, 2100 C, or
more when the
feedstock comprises steel (e.g., carbon steel, stainless steel, etc.) or
alloys. The temperature may
be at most about 2100 C, 2050 C, 2000 C, 1950 C, 1900 C, 1850 C, 1800
C, 1750 C,
1700 C, 1650 C, 1600 C, 1590 C, 1580 C, 1570 C, 1560 C, 1550 C, 1540
C, 1530 C,
1520 C, 1510 C, 1500 C, 1490 C, 1480 C, 1470 C, 1460 C, 1450 C, 1440
C, 1430 C,
1420 C, 1410 C, 1400 C, 1390 C, 1380 C, 1370 C, 1360 C, 1350 C, 1340
C, 1330 C,
1320 C, 1310 C, 1300 C, 1290 C, 1280 C, 1270 C, 1260 C, 1250 C, 1240
C, 1230 C,
1220 C, 1210 C, 1200 C, or less when the feedstock comprises steel or
alloys.
[0093] In some cases, the heat generated at the local area at the contact
between the
feedstock and the support may not vary depending on a material of the
feedstock (e.g., the wire).
Alternatively, the heat generated at the local area at the contact between the
feedstock and the
support may vary depending on the material of the feedstock.
[0094] In some embodiments, based at least in part on a type or composition
of the alloy, the
melting point of the alloy may be lower than a melting temperature of one or
more base metals
of the alloy. Alternatively, based at least in part on a type or composition
of the alloy, the
melting point of the alloy may be higher than the melting temperature of the
one or more base
metals of the alloy. As another alternative, based at least in part on a type
or composition of the
alloy, the melting point of the alloy may be about the same as the melting
temperature of the one
or more base metals of the alloy. In some embodiments, the feedstock (e.g. a
wire) may
superheat at a melt pool.
[0095] The electric current from the guide to the feedstock and to the
support, or vice versa,
may range from about 10 Amperes (A) to about 20000 A. The electric current may
be at least
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about 10 A, 20 A, 30 A, 40 A, 50 A, 60 A, 70 A, 80 A, 90 A, 100 A, 200 A, 300
A, 400 A, 500
A, 600 A, 700 A, 800 A, 900 A, 1000 A, 2000 A, 3000 A, 4000 A, 5000 A, 6000 A,
7000 A,
8000 A, 9000 A, 10000 A, 20000 A, or more. The electric current may be less
than or equal
about 20000 A, 10000 A, 9000 A, 8000 A, 7000 A, 6000 A, 5000 A, 4000 A, 3000
A, 2000 A,
1000 A, 900 A, 800 A, 700 A, 600 A, 500 A, 400 A, 300 A, 200 A, 100 A, 90 A,
80 A, 70 A, 60
A, 50 A, 40 A, 30 A, 20 A, 10 A or less. The duration of the application of
the current may
range from about 0.01 seconds (s) to about 1 s. The duration of the
application of the current
may be at least about 0.01 s, 0.02 s, 0.03 s, 0.04 s, 0.05 s, 0.06 s, 0.07 s,
0.08 s, 0.09 s, 0.1 s, 0.2
s, 0.3 s, 0.4 s, 0.5 s, 0.6 s, 0.7 s, 0.8 s, 0.9 s, 1 s or more. The duration
of the application of the
current may be less than or equal about 1 s, 0.9 s, 0.8 s, 0.7 s, 0.6 s, 0.5
s, 0.4 s, 0.3 s, 0.2 s, 0.1 s,
0.09 s, 0.08 s, 0.07 s, 0.06 s, 0.05 s, 0.04 s, 0.03 s, 0.02 s, 0.01 s or
less.
[0096] The material for the support may be selected for good electrical
conductivity and
compatibility with the feedstock that is being deposited as segments. The
material for the
support may have a higher electrical conductivity than the feedstock.
Alternatively or in addition
to, the material for the support may have substantially the same or a lower
electrical conductivity
than the feedstock. The support may be non-consumable and thus may not require
replacement
during normal operation. Alternatively or in addition to, the support may be
replaced after
printing one or more 3D objects. The support may be chosen to allow weak
adhesion of the
deposited segments to it, so that a first layer of deposited segments may hold
the at least the
portion of the 3D object firmly in place on the support during further
deposition. The material
for the support may have a higher electrical conductivity than the feedstock.
The material for the
support may not alloy with the feedstock. The material for the support may
have a higher
thermal conductivity than the feedstock, such that heat generated at an area
of the feedstock
deposition may be quickly conducted away. For example, if the deposited metal
is steel, copper
or aluminum may be appropriate materials for the support. Alternatively or in
addition to, the
material for the support may have substantially the same or lower thermal
conductivity than the
feedstock to maintain the heat generated at the area of the feedstock
deposition.
[0097] The application of electric current may be controlled to influence
the deposition of
segments (e.g., size, shape, etc.). An open-loop control of the electric
current may be enabled
via choosing a desired intensity level and/or duration of power prior to the
deposition of
segments. The desired intensity level and/or duration of power may be assigned
on the power
source or the controller operatively coupled to the power source. The desired
intensity level of
the power may be calibrated to achieve a specific voltage or current at a
constant contact
resistance between the feedstock and the support. Alternatively or in addition
to, a closed-loop
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control may be used. The closed-loop control may comprise a force sensor or an
electrical
measurement meter (e.g., a voltmeter, ammeter, potentiometer, etc.)
electrically coupled to the
guide of the print head, the feedstock, the support, the power source, and/or
the controller
operatively coupled to the power source. In the closed-loop control, voltage
and current to the
tip of the feedstock may be measured in situ during deposition of the
segments, and the contact
resistance between the feedstock and the support may be calculated according
to Equation 2 (i.e.,
Ohm's Law):
V
R = ¨1 (Equation 2)
where V is the voltage,
1 is the electric current, and
R is the contact resistance between the feedstock and the support.
The closed-loop control may beneficially eliminate failed parts due to
incomplete fusion of
segments and minimize heat input into the structure during deposition.
[0098] Because the contact resistance is calculated dynamically, the power
of the applied
electric current may be precisely controlled, thus resulting in an exact
amount of heat being
applied during deposition of a segment from the feedstock. The power source
may supply an
alternating current (AC) or a direct current (DC) to the feedstock and/or the
support under an
applied voltage. The applied voltage may range from about 1 millivolt (mV) to
about 100 volt
(V). The voltage may be at least about 1 mV, 2 mV, 3 mV, 4 mV, 5 mV, 6 mV, 7
mV, 8 mV, 9
mV, 10 mV, 20 mV, 30 mV, 40 mV, 50 mV, 60 mV, 70 mV, 80 mV, 90 mV, 100 mV, 200
mV,
300 mV, 400 mV, 500 mV, 600 mV, 700 mV, 800 mV, 900 mV, 1 V, 2 V, 3 V, 4 V, 5
V, 6 V, 7
V, 8 V, 9 V, 10 V, 20 V, 30 V, 40 V, 50 V, 60 V, 70 V, 80 V, 90 V, 100 V, or
more. The
applied voltage may be less than or equal about 100 V, 90 V, 80 V, 70 V, 60 V,
50 V, 40 V, 30
V, 20 V, 10 V, 9 V, 8 V, 7 V, 6 V, 5 V, 4 V, 3 V, 2 V, 1 V, 900 mV, 800 mV,
700 mV, 600 mV,
500 mV, 400 mV, 300 mV, 200 mV, 100 mV, 90 mV, 80 mV, 70 mV, 60 mV, 50 mV, 40
mV,
30 mV, 20 mV, 10 mV, 9 mV, 8 mV, 7 mV, 6 mV, 5 mV, 4 mV, 3 mV, 2 mV, 1 mV or
less.
[0099] In some examples, one pole of the power source is attached to the
feedstock (e.g.,
through a guide of the print head) and another pole of the power source is
attached to the
support.
[00100] The controller, the preload roller, the rotational actuator coupled
to the preload roller,
and the force sensor, current sensor and/or the rotary sensor of the
rotational actuator may form a
real-time closed-loop feedback system to control the force exerted on the
feedstock. The real-
time closed-loop feedback system may allow automated use of a wide range of
feedstock
dimensions and feedstock materials. The real-time closed-loop feedback system
may allow: (1)
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control of power or motion system (2) control of wire feeding speed (3)
dynamic compatibility
with feedstocks of varying cross-sectional dimensions; (4) dynamic
compatibility with
feedstocks of varying materials and/or stiffness; (5) dynamic measurement of
the feedstock
cross-sectional dimension; (6) prevention or reduction of feedstock slippage
from the gap; and
(7) increasing life span of the rollers. For example, the measured reaction
force may adjust the
master or slave feeding system control, e.g. wire feed speed. The speed
adjustment and control
may be in real-time and may be continuous. The real-time closed-loop feedback
system may
prevent at least some of print failures due to failed feedstock feeding to
improve print quality.
Additionally, the force sensor may predict and prevent sparks, which
significantly reduce to print
quality.
[00101] The system may comprise an optical sensor to measure the diameter of
at least a
portion of the feedstock before the at least the portion of the feedstock is
fed through the
assembly comprising the preload roller, the driver roller, and the gap
adjusting mechanism that
adjusts the size of the gap between the two rollers. The optical sensor may be
configured
between the assembly and the feedstock source. The optical sensor and the
assembly may be
operatively coupled to the controller. In an example, the optical sensor may
be a camera that
captures an image of the at least the portion of the feedstock and calculates
the approximate
diameter of the at least the portion of the feedstock. According to the
calculated diameter of the
at least the portion of the feedstock, the controller may direct the gap
adjusting mechanism to
adjust the gap between the two rollers, thereby maintaining the forces exerted
on the feedstock
approximately constant.
[00102] In some cases, the preload roller may comprise a rotary sensor
(e.g., a resolver,
encoder, etc.) that is operatively coupled to the controller. Examples of the
encoder include an
optical encoder and a rotary encoder. The encoder may be an auxiliary encoder.
The rotary
sensor of the preload roller may provide position and/or speed feedback. In
some cases, the
controller may use the rotary sensor to track rotation of preload roller and
determine a length of
the feedstock that is fed through the gap between the preload roller and the
driver roller. In some
cases, the controller may detect when the preload roller rapidly stops
rotating, which may
indicate slippage of the feedstock away from the gap.
[00103] In some cases, the preload roller may comprise a force sensor to
measure a contact
force between the preload roller and the feedstock. The outer shell of the
preload roller may
comprise an encoder disc that is responsive to an exerted pressure, and the
inner shell of the
preload roller may comprise an encoder sensor that can measure and record the
response of the
encoder disc to the exerted pressure. For example, the outer shell of the
preload roller may
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comprise a piezoelectric disc that generates piezoelectricity in response to
an applied pressure by
the feedstock. The inner shell of the preload roller may comprise an encoder
sensor that can
measure and record the change in the piezoelectricity of the preload roller
while the feedstock is
fed through the assembly towards or away from the guide. A sudden drastic drop
in the
piezoelectricity may indicate a slippage of the feedstock from the gap between
the preload roller
and the driver roller.
[00104] Other characteristics analyzed may comprise one or more elements
selected from the
group consisting of travel direction, voltage, characteristic profiles with
changing feed rates for
X, Y, and Z travel, feeding and retraction of the wire, power loss during
print, comparison of
WFS data to other sensor data, impulse response, step response of at least a
portion of the 3D
print, layer-layer characteristics during print, hot and cold ends of the
part, lifting pen, layer layer
patterns, parallel offsets, middle offsets, arbitrary offsets, perpendicular
patterns, arbitrary
patterns. The parameter may be the total mass of the wire feeder and rigidity
and damping
changes to its mounting.
[00105] FIG. 19 schematically illustrates an example of wire feeding method
("method")
1901. This method may be used with other methods of the present disclosure. In
operation 1910,
the method 1901 comprises activating a 3D printing system. The 3D printing
system may
comprise one or more components of the system for printing the 3D object, as
provided herein.
In an example, the 3D printing system has one or more components of the sensor
assembly 200,
as illustrated in FIG. 2.
[00106] With continued reference to FIG. 19, in operation 1920, a wire (e.g.,
a feedstock) is
supplied through a groove in a roller (e.g., a driver roller) of the 3D
printing system. Next, in
operation 1930, one or more parameters of the wire (or associated with the
wire) associated with
passage of the wire through a guide towards a support of the 3D printing
system may be
adjusted. In operation 1940, a force (e.g., a reaction force) exerted on the
wire by the support
may be measured. Next, in operation 1950, a measured force (or a plurality of
measured forces
at one position on the wire in contact with the support) may be compared to a
threshold, and a
determination is made as to whether the force is below the threshold.
[00107] The threshold may be a pre-determined threshold value or range of the
force. The
threshold may be a force acceptable by the wire without experiencing
significant damage (e.g.,
deformation or cut). The threshold may be a force acceptable by the support
without
experiencing a significant damage (e.g., deformation or cut). The threshold
may be specific for a
type of material the wire is made of Alternatively or in addition to, the
threshold may be a
common threshold for different types of materials that different wires are
made of.
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[00108] In operation 1950, when the measured force exerted on the wire is
above the
threshold ("NO"), the method 1901 may comprise adjusting, in operation 1930,
the one or more
parameters (e.g., wire feed speed, distance between wire tip and previously
printed portion of the
3D object) of the wire (or associated with the wire) associated with passage
of the wire through
the guide towards the support, such that the force exerted on the wire is
decreased.
Alternatively, in operation 1950, when the measured force exerted on the wire
is equal to or
below the threshold ("YES"), the method 1901 may comprise using, in operation
1960, an
actuator (e.g., an actuator coupled to the driver roller) to direct the wire
through the groove and
towards the guide. The guide may be part of a print head of the 3D printing
system. In
operation 1970, the method 1901 may further comprise supplying electrical
current from the
guide through the wire and to the support (or vice versa), under conditions
sufficient to melt the
wire when the wire is in contact with the support or a portion of a 3D object.
[00109] In another aspect, the present disclosure provides a method for
printing a three-
dimensional (3D) object adjacent to a support (e.g., base), comprising
receiving in computer
memory a computational representation of the 3D object, and using a print head
to initiate
printing of the 3D object by, (i) directing at least one feedstock through a
feeder towards the
support and (ii) flowing electrical current through the at least one feedstock
and into the support,
or vice versa. Next, the at least one feedstock may be subjected to heating
upon flow of
electrical current through the at least one feedstock and into the support, or
vice versa, which
heating is sufficient to melt at least a portion of the at least one
feedstock. At least one layer of
the at least the portion of the at least one feedstock, or the at least the
portion of the at least one
feedstock, may be deposited adjacent to the support in accordance with the
computational
representation of the 3D object, thereby printing the 3D object.
[00110] A
relative position of at least one end of the at least one feedstock (e.g., a
tip of a
wire) may be changed with respect to the at least one layer. A size of the at
least the portion of
the at least one feedstock may be controllable relative to the feedstock
during deposition.
[00111] The method may further comprise repeating the deposition of at least
one layer of the
at least the portion of the at least one feedstock, or the at least the
portion of the at least one
feedstock, one or more times to deposit and shape additional portion(s) of the
at least one
feedstock or at least one other feedstock adjacent to the support.
Force Analysis
[00112] The back-force at the wire may be measured by isolating the force of
friction coming
through the sheath (F3-2) from the force that the feed hob imposes on the wire
(F2-1). The force
that the gantry imparts on the print head may not be measured. A subset of the
equations in
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tables 1 and 2 may be analyzed and manipulated to assess adaptability of such
measurements.
The equations may be manipulated on the left, so that the position of each
variable is consistent.
On the right, a factor applied to each equation is presented. This factor may
be derived
empirically. The algebra can be preserved here, as one true equation may be
added to another
true equation any number of times.
Table 1
Equation Note
Sum of forces on the wire (in
Fiz = F4_1 + F2_1 + F3_1z = 0
the Z direction)
Sum of forces on the wire (in
Fix = F3-1X + F5-1 =
the X direction)
F1A = F4-1 + F2-1 + F3-1Z +F3_1X + F5-1 +
W1 = 0 Sum of axial wire forces
Sum of forces on the extruder
F2 = F6_2 ¨ F2_1 + F3_2 + W2 = 0
(Z direction)
Sum of forces on the sheath
F3Z = ¨F3-1Z ¨ F3-2 + W3 =
(in the Z direction)
Sum of forces on the sheath
F3X = ¨F3-1X + F7-3 =
(in the X direction)
F3A = ¨F3_2 ¨ F3_1z ¨ F3_1x ¨ F7_3 ¨ W3 = 0 Sum of axial sheath forces
Table 2
Value Status
F4-1 Unknown, Backforce (value of interest)
F3-1X Unknown, force of the sheath on the wire (horizontal)
F3-1Z Unknown, force of the sheath on the wire (vertical)
F5-1 Unknown, force the spool applies to the wire
F7_3 Unknown, force of ground on the sheath
F2-1 Known if measured, force the hob applies to the wire
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F6-2 Known if measured, force of gantry on extruder.
F3_2 Known if measured, force of the sheath on the extruder.
Known if assumed constant, weight of the wire
W2 Known if assumed constant, weight of the extruder.
W3 Known if assumed constant, weight of the sheath.
Table 3
Equation Factor
F2_1 + 0 + F3_iz + F4_1 + 0 + 0 + 0 + 0 = ¨W1 2
0 + F3_ix+0+0+Fs_i+0+0+0=0 1
F2_1 + F3_ix + F3_iz + F4_1 + F5_1 + 0 + 0 + 0 = ¨W1 -1
0 + 0 ¨ F3_iz + 0 + 0 ¨ F3_2 + 0 + 0 = ¨W3 2
0 ¨ F3_ix+0+0+0+0+0+F7_3=0 1
0 ¨ F3_1x ¨ F3_iz + 0 + 0 ¨ F3_2 + 0 + F7_3 += ¨W3 -1
[00113] The equations in table 3, once multiplied by their respective
factors, can be expressed
as the dot product of two matrices equated to one another. Once the equations
are expressed in a
matrix as in equation 3, the columns can be summed to create another equation.
This process
may be a quicker way of adding these equations or merging them by
substitution. The factors
applied to each equation can be modified until an equation is in the correct
terms. In this
example, the force between the wire and the part ( F4-1 ) can be deduced if
the force applied by
the hob to the wire (F2-1) is measured and the force applied by the sheath to
the extruder ( F3-2)
is measured.
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2 0 2 2 0 0 0 0 F2 2W1
01 0 0 1 0 0 0 F3 ix
-1-1-1-1-10 00 F3 WI
12
0 0 -2 0 0 -2 0 0 = F4 1 =-2W3
0 -1 0 0 0 0 0 1 F5 0
0 1 1 001 0-1 F3 2, flir3
-176 2
F7 3
(Equation 3)
[00114] The factors may be manipulated until there is one value in the
1st, 4th, 6th
column, the relationships of interest is between F2-1, F4-1, and F3-2. This
demonstrates that the
force between the wire and the part can be the force that the hob imparts on
the wire, minus the
force that the sheath imparts on the extruder, plus the unsupported weight of
the wire and the
unsupported weight of the sheath.
1 0 0 1 0 - 1 0 0 = [Forces] = ¨W1 ¨W3 (Equation 4)
F2-1 + F4-1 ¨ F3-2 = ¨W1 ¨ W3 (Equation 5)
F4-1 = ¨F2_1 + F3_2 ¨ W1 ¨ W3 (Equation 6)
[00115] In some cases, the back-force on the wire may be determined by
measuring the
force that the gantry applies to the print head (F6-2) and taring a weight of
one or more printing
components. The one or more printing components may be selected from the group
consisting of
sensor, frame system, mount plate, drive motor, driver roller, preload motor,
and preload roller.
The equations as mentioned above may be adjusted to as verification of this
measurement. For
example, the equations may be manipulated on the left, so that the position of
each variable
remains consistent. On the right of the tables, a factor applied to each
equation is shown. This
factor may be derived empirically.
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Table 4
Equation
Factor
F2_1 + 0 + F3_iz + F4_1 + 0 + 0 + 0 + 0 = ¨V171 1
0+F3_1x+0+0+F5_1+0+0+0=0 -1
F2-1 + F3-1X + F3-1Z + F4-1 + F5_1 + 0 + 0 + 0 = ¨W1 1
¨F2_1 + 0 + 0 + 0 + 0 + F3_2 + F6_2 + 0 = ¨W2 2
1
0¨F3_ix+0+0+0+0+0+F7_3 =0 -1
1
1001161 The equations above, once multiplied by their respective factors,
can be expressed
as the dot product of two matrices equated to another. Once the equations are
expressed in a
matrix in equation 7, the columns may be summed to create another equation.
The factors
applied to each may be modified until an equation is in the correct terms. In
this case, the force
between the wire and the part (F4-1) may be deduced if the force applied from
the gantry to the
extruder (F6-2) is measured and weights of system components are determined.
1 0 1 1 0 0 0 0 P
¨ 2: 1 1
0-1 0 0-1 0 0 0 F3 I X' 0
1 1 1 1 1 0 0 0 F3 1Z ¨1
-2 0 0 0 0 2 2 0 F4 1 = -2W2
0 0 -1 0 0 -1 0 0 F5 3
0 1 0 0 0 0 0-1 F3 2 0
0 -1 -1 0 0 -1 0 1 F ¨
7 3
(Equation 7)
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[00117] The factors may be manipulated until there is a value in the 4th
and 7th column,
as the relationship between F4-1 and F6-2 are of interest.
0 0 0 2 0 0 2 0 = [Forces] = ¨2W1 ¨ 2W2 ¨ 2W3 (Equation 8)
2(F4_1 + F6_2) = ¨2(W1 + W2 + W3) (Equation 9)
F4-1 = -(F6-2 + W1 + W2 + W3) (Equation 10)
[00118] The force between the wire and the part may be the force that the
gantry imparts
on the extruder, minus the weight of the extruder, the unsupported weight of
the wire and the
sheath.
Wire Force Sensing Modeling
[00119] The performance of a system may be characterized and the load on the
sensors and/or
feedstock, e.g. wire, may be measured in isolation from the motors and
rollers. The wire force
sensing modeling can determine whether decreasing the sensor weight may result
in improved
performance on the sensors. In some cases, the modeling can estimate
performance of the
sensors so that sensor performance is not compromised with additional weight.
[00120] The WFS system may be modeled as a linear time invariant (LTI) -
lumped
parameter system. Using standard ordinary differential equations (ODEs), and
their solutions, the
WFS may be analyzed and then optimized using the mass (m), spring constant
(k), and damping
ratio (b). The optimized values form and b may be m = 0.3 kg and b =182
(N*s)/m. The WFS
may be sensitive enough to distinguish the difference between different
quality of prints.
[00121] The mechanical, electrical, thermal, or fluidic systems may be
analyzed by creating
an LTI lumped parameter system. In the case of the WFS system, it can be
represented
accurately by an underdamped, second order mass-spring-damper model (m ¨ k ¨ b
model). The
spring constant may be calculated using the strain gauge specification sheets
and the mounting
brackets. The damping constant may be tuned to match the exponential decay of
the test data.
The mass of the system can be directly measured. FIG. 3 shows a representation
of the m ¨ k ¨ b
model 300 used for analysis. The representation is a mass (m) 305, spring (k)
310, damper (b)
315 lumped parameter model, with a force input and direction 320.
[00122] In one example, the mass of the wire feeder was measured to be 0.47kg.
The spring
constant (kT) is a composite spring comprising three strain gauge springs
(ksGeg =3 *ksG) in a
series with the mounting bracket (km). Equation 11 shows the formula for the
total spring
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constant kT, which may be a function of the strain gauge and mounting bracket
constants.
ksGeg *km
kT = (Equation 11)
(ksGeq+km)
[00123] Conducting a force balance generates the ODE for the m ¨ k ¨ b model.
Equations 12
and 13 show the solution to this ODE for the underdamped case, in regular and
polar form
respectively.
x(t) = * 1 ¨ e't * (cos(cod * t) + * sin(cod * t)) (Equation 12)
kT &id
x(t) = * (1 * e't * sin (co d * t + a tan (=))) (Equation 13)
kT COcl
[00124] The damping ratio (b) and mounting spring constant (km) may be tuned
to match the
response of testing data. The WFS may be tested under a variety of conditions
to generate the
characteristic second order response. The exponential decay constant, and the
frequency of
oscillation from the data can be used to set b and km. After the model is
tuned, the sensed force,
e.g. the strain gauge force, can be calculated in response to a step input.
FIG. 4 shows an
example step response of the strain gauge force reading, which matches
experimental data.
[00125] The response time ttpeak, land settling time @settle) may be
calculated as a function of
(t peak)
the damped natural frequency and the exponential decay rate, respectively.
Equations 14 and 15
show these formulas, which can be used to optimize this response.
n.
tpeak:= ¨wc1= 0.01S (Equation 14)
¨1
tsettle := 7 * ln(0.02) = 0.317 s(E quation 15)
[00126] Once the model is representative of the data collected during
testing, the m, k, and b
parameters can be tuned to optimize the response. In this case, tpeak __. ic
adequate (less than ¨0.015
_
s), but the tsettle is more than ten times the target of 0.02 s. The tsettle
may be reduced without
increasing t significantly. This can be analyzed using a graph of t _peak
_peak and tsettle as a function of
b, for various m. The spring constant, k, is not in question because tsettle,
is not a function of k.
FIG. 5 shows the graph used for such optimization, and FIG. 6 shows a
theorized optimized step
response. In FIG. 5, tsettle is represented by dotted lines and tpeak __. ic
represented by solid lines as a
_
function of b, for m=0.2 kg, 0.3 kg, 0.4 kg, and 0.47 kg. The intersection
points between the
dotted line and solid line represents the optimal response. For example, when
m is 0.3kg, the
intersection is t = 0.013 (<0.015). The optimal values are m=0.3 kg and b=182
(N*s)/m. FIG. 6
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illustrates the optimized step response of sensed force for a step input of 10
N and tpeak and t settte
= 0.013 seconds.
Computer systems
[00127] FIG. 7 shows a computer system 701 that is programmed or otherwise
configured to
communicate with and regulate various aspects of a 3D printer of the present
disclosure. The
computer system 701 can communicate with a power source, one or more
actuators, or one or
more sensors of the 3D printer. The computer system 701 can direct the power
source to supply
electrical current to a feedstock for use in printing a 3D object. The
computer system 701 may
also be programmed to communicate with one or more feedstock feeding
assemblies. Each
feedstock feeding assembly may comprise a driver roller, preload roller, and
one or more sensors
and the computer system 701 can be programmed to communicate with the driver
roller, preload
roller, and sensors independently or simultaneously. The computer system 701
can accelerate,
decelerate, maintain at a given speed of a plurality of rotating speeds, or
control the amount of
power applied to the wire feeding assembly. The computer system 701 can be
programmed to
use the sensors to measure a reaction force of the wire.
[00128] The computer system 701 can be an electronic device of a user or a
computer system
that is remotely located with respect to the electronic device. The electronic
device can be a
mobile electronic device.
[00129] The computer system 701 includes a central processing unit (CPU, also
"processor"
and "computer processor" herein) 705, which can be a single core or multi core
processor, or a
plurality of processors for parallel processing. The computer system 701 also
includes memory
or memory location 710 (e.g., random-access memory, read-only memory, flash
memory),
electronic storage unit 715 (e.g., hard disk), communication interface 720
(e.g., network adapter)
for communicating with one or more other systems, and peripheral devices 725,
such as cache,
other memory, data storage and/or electronic display adapters. The memory 710,
storage unit
715, interface 720 and peripheral devices 725 are in communication with the
CPU 705 through a
communication bus (solid lines), such as a motherboard. The storage unit 715
can be a data
storage unit (or data repository) for storing data. The computer system 701
can be operatively
coupled to a computer network ("network") 730 with the aid of the
communication interface
720. The network 730 can be the Internet, an internet and/or extranet, or an
intranet and/or
extranet that is in communication with the Internet. The network 730 in some
cases is a
telecommunication and/or data network. The network 730 can include one or more
computer
servers, which can enable distributed computing, such as cloud computing. The
network 730, in
some cases with the aid of the computer system 701, can implement a peer-to-
peer network,
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which may enable devices coupled to the computer system 701 to behave as a
client or a server.
[00130] The CPU 705 can execute a sequence of machine-readable instructions,
which can be
embodied in a program or software. The instructions may be stored in a memory
location, such
as the memory 710. The instructions can be directed to the CPU 705, which can
subsequently
program or otherwise configure the CPU 705 to implement methods of the present
disclosure.
Examples of operations performed by the CPU 705 can include fetch, decode,
execute, and
writeback.
[00131] The CPU 705 can be part of a circuit, such as an integrated circuit.
One or more
other components of the system 701 can be included in the circuit. In some
cases, the circuit is
an application specific integrated circuit (ASIC).
[00132] The storage unit 715 can store files, such as drivers, libraries
and saved programs.
The storage unit 715 can store user data, e.g., user preferences and user
programs. The computer
system 701 in some cases can include one or more additional data storage units
that are external
to the computer system 701, such as located on a remote server that is in
communication with the
computer system 701 through an intranet or the Internet.
[00133] The computer system 701 can communicate with one or more remote
computer
systems through the network 730. For instance, the computer system 701 can
communicate with
a remote computer system of a user. Examples of remote computer systems
include personal
computers (PC) (e.g., portable PC), slate or tablet PC's (e.g., Apple iPad,
Samsung Galaxy
Tab), telephones, Smart phones (e.g., Apple iPhone, Android-enabled device,
Blackberry ), or
personal digital assistants. The user can access the computer system 701 via
the network 730.
[00134] Methods as described herein can be implemented by way of machine
(e.g., computer
processor) executable code stored on an electronic storage location of the
computer system 501,
such as, for example, on the memory 710 or electronic storage unit 715. The
machine executable
or machine readable code can be provided in the form of software. During use,
the code can be
executed by the processor 705. In some cases, the code can be retrieved from
the storage unit
715 and stored on the memory 710 for ready access by the processor 705. In
some situations, the
electronic storage unit 715 can be precluded, and machine-executable
instructions are stored on
memory 710.
[00135] The code can be pre-compiled and configured for use with a machine
having a
processer adapted to execute the code, or can be compiled during runtime. The
code can be
supplied in a programming language that can be selected to enable the code to
execute in a pre-
compiled or as-compiled fashion.
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[00136] Aspects of the systems and methods provided herein, such as the
computer system
501, can be embodied in programming. Various aspects of the technology may be
thought of as
"products" or "articles of manufacture" typically in the form of machine (or
processor)
executable code and/or associated data that is carried on or embodied in a
type of machine
readable medium. Machine-executable code can be stored on an electronic
storage unit, such as
memory (e.g., read-only memory, random-access memory, flash memory) or a hard
disk.
"Storage" type media can include any or all of the tangible memory of the
computers, processors
or the like, or associated modules thereof, such as various semiconductor
memories, tape drives,
disk drives and the like, which may provide non-transitory storage at any time
for the software
programming. All or portions of the software may at times be communicated
through the
Internet or various other telecommunication networks. Such communications, for
example, may
enable loading of the software from one computer or processor into another,
for example, from a
management server or host computer into the computer platform of an
application server. Thus,
another type of media that may bear the software elements includes optical,
electrical and
electromagnetic waves, such as used across physical interfaces between local
devices, through
wired and optical landline networks and over various air-links. The physical
elements that carry
such waves, such as wired or wireless links, optical links or the like, also
may be considered as
media bearing the software. As used herein, unless restricted to non-
transitory, tangible
"storage" media, terms such as computer or machine "readable medium" refer to
any medium
that participates in providing instructions to a processor for execution.
[00137] Hence, a machine readable medium, such as computer-executable code,
may take
many forms, including but not limited to, a tangible storage medium, a carrier
wave medium or
physical transmission medium. Non-volatile storage media include, for example,
optical or
magnetic disks, such as any of the storage devices in any computer(s) or the
like, such as may be
used to implement the databases, etc. shown in the drawings. Volatile storage
media include
dynamic memory, such as main memory of such a computer platform. Tangible
transmission
media include coaxial cables; copper wire and fiber optics, including the
wires that comprise a
bus within a computer system. Carrier-wave transmission media may take the
form of electric or
electromagnetic signals, or acoustic or light waves such as those generated
during radio
frequency (RF) and infrared (IR) data communications. Common forms of computer-
readable
media therefore include for example: a floppy disk, a flexible disk, hard
disk, magnetic tape, any
other magnetic medium, a compact disc read-only memory (CD-ROM), digital
versatile disc
(DVD) or digital versatile disk - read only memory (DVD-ROM), any other
optical medium,
punch cards paper tape, any other physical storage medium with patterns of
holes, a random
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access memory (RAM), a read-only memory (ROM), a programmable read-only memory
(PROM) and erasable programmable read-only memory (EPROM), a FLASH-EPROM, any
other memory chip or cartridge, a carrier wave transporting data or
instructions, cables or links
transporting such a carrier wave, or any other medium from which a computer
may read
programming code and/or data. Many of these forms of computer readable media
may be
involved in carrying one or more sequences of one or more instructions to a
processor for
execution.
[00138] The computer system 701 can include or be in communication with an
electronic
display 735 that comprises a user interface (UI) 740 for providing, for
example, (i) activate or
deactivate a 3D printer for printing a 3D object, (ii) determine a reaction
force exerted by the
support against the at least one wire, or (iii) determine a wire feed speed or
amount of power
applied to the wire feeding assembly. Examples of UI' s include, without
limitation, a graphical
user interface (GUI) and web-based user interface.
[00139] Methods and systems of the present disclosure can be implemented by
way of one or
more algorithms. An algorithm can be implemented by way of software upon
execution by the
central processing unit 705. The algorithm can, for example, (i) determine a
reaction force
exerted by the support against the at least one wire, or (ii) dynamically
change the wire feed
speed or amount of power applied to the wire feeding assembly for printing a
3D object.
EXAMPLES
[00140] The examples below are illustrative and non-limiting
Example 1
[00141] Prior to printing the 3D object, a calibration procedure may be
used by
suspending a known weight from a piece of fed wire. The calibration of the WFS
can be
performed as a system, instead of individually for each strain gauge. The
system may self
calibrate. The calibration range may be in the compression state of the strain
gauges, while the
primary forces exerted by the wire back force may be in the tension regime of
the strain gauges.
First, it may be determined whether calibrating each strain gauge separately
is required, or if the
WFS may be calibrated as a system. FIG. 8 shows three sensors' individual
readings in volts and
the sum (bottom most curve) of the three sensors for a series of loads. This
test may be
performed on a test fixture. Based on this test, the simplified calibration
procedure of adding the
sensor readings of each strain gauge may be used, allowing for work with one
output (summed
voltage) that may result in less noise than the individual sensor readings.
This may be due to the
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averaging of individual sensor noise. In some cases, using three sensors can
result in less noise
than using one sensor.
[00142] FIG. 9 is the second calibration of the system, a more detailed
version of FIG 8.
This calibration is performed once using a WFS on the printer. Each load is
measured three times
and with capacity for additional loads to be used, e.g. focusing on near zero
load. Additionally,
more samples are used in determining the degree of variation. For tests on the
test fixture, the
calibration from FIG. 8 is used. For tests on the 3D printer, the calibration
from FIG. 9 is used.
The strain gauges are retightened while on the 3D printer, which may have
changed the intercept
of the calibration. The slope of the calibration may not be altered
significantly.
Example 2
[00143] FIG. 10 shows the system response while the feeder motor is
powered but
stationary and a hammer is used to hit the wire tip into the contact tip. The
testing illustrates how
quickly the system would respond and how quickly to review data and use it in
the control
system. From the data, the response time (plotted as peaks and troughs) of the
WFS is 0.0038s.
Response time may be defined as the time to reach the first peak. The 2%
settling time of the
WFS is 0.1089s. The 2% settling time limits are plotted as horizontal lines.
Example 3
[00144] FIG. 11 and FIG. 12 show measurements as a wire is driven through
a wire feeder
and illustrates the sensor noise in determining the type of sensor filtering
required in a control
system. FIG. 11 illustrates measurements of a friction load applied to the
wire. Alternatively, in
FIG. 12, the wire is freely driven. Both these tests are performed on the test
fixture and the data
is obtained from the WFS. The line is a 100-point moving average of the data
and an effective
low pass filter of the system response. The average delta from the moving
average in Table 5 and
Table 6 is the average of each data point minus the 100-point moving average.
The maximum
value in these tables is the maximum distance a data point is from the moving
average. The
standard deviation is calculated over that noted stretch of the data. Based on
the results shown in
Table 5 and Table 6, the system noise is not affected by the load. The
baseline sensor noise is
around 0.12N and the current wire driver contributes 0.73N additional noise to
measurements.
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Table 5
Sample Time Range 5.2 to 5.7 15 to 17
Ave. Delta to Moving Average 1.432 0.158
Max 4.439 0.890
STD Dev 0.847 0.120
Table 6
Sample Time Range 3.9 to 5.9 1 to 3
Ave. Delta to Moving Average 1.202 0.167
Max 3.850 0.865
STD Dev 0.882 0.125
Example 4
[00145] FIG. 13 illustrates test data
from printing a line while changing the extrusion
ratio. The extrusion ratio is the starting cross-sectional area of the wire
divided by the cross-
sectional area of the wire after extrusion. FIG. 14 shows the result of the
test print, roughly lined
up with FIG. 13. For this test, the feed rate is constant and set to 4000
mm/min. Each segment of
the line where a feed rate change occurred is marked by a vertical line.
Various segments are
illustrated. Segment 1305 has an extrusion ratio of 1. Segment 1310 has an
extrusion ratio of
1.15. Segment 1315 has an extrusion ratio of 1.3. Segment 1320 has an
extrusion ratio of 1.45.
Segment 1325 has an extrusion ratio of 1.6. Segment 1330 has an extrusion
ratio of 1.75.
Segment 1335 has an extrusion ratio of 0. Segment 1325 prints the smoothest
(in FIG. 14), the
standard deviation is 0.510 N with an average load of 0.379N. The standard
deviation may be
compared to recorded data from the same test where there is no motion (0.014N)
and where there
is noise while moving the gantry at the same speed without printing (0.822N).
The graph
illustrates that a different response in data correlates to a different
response in the actual print.
When noise is first observed in the printing process, the printing parameter
in the control system
may be adjusted. However, in some cases, various noises may result from the
resultant print.
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[00146] The segment of the test while moving but not printing (bottom
curve) is shifted
below the printing test data (top curve) for comparison. The top curve has a
clear pattern with
multiple frequencies while being larger in magnitude than the bottom curve
(the clean print).
Example 5
[00147] FIG. 15 illustrates a pair of tests 1520 and 1525 stacked on top
of one another
during printing of corner turns in portions of an object. The printer
initiates printing at 1505 for
40 mm in one direction, then turns 900 at 1510 and prints another 40 mm until
the print stops at
1515. Of the trials performed, none shows a definitive signal at the corner
turn. The sensors may
not detect a specific response from turning as this movement may not affect
the axial forces. The
noises in FIG. 15 may be purely a measure of print quality. As a result, when
analyzing resultant
noise from a print, that from a printing head changing direction may not need
to be filtered from
the resultant noise.
Example 6
[00148] FIG. 16 and FIG. 17 are a series of tests in which the wire is
pushed with a specified
feed length into a solid piece of metal. FIG. 16 shows the amount of force
read by the sensors. In
some cases, there may be system movement from the other printing components,
e.g. load cells.
As a result, when the wire is pushed down, the system is not fully rigid. As
shown in FIG. 17, the
feed rate indicates that a ramp loading of the WFS occurred rather than a step
load. During the 2
mm feed test, there is an audible skip. The current wire feeder slips at about
30 Newtons (N)
based on this data. In other examples, the wire feeder slips a little higher
at about 35N-45N.
[00149] Curve 1605 illustrates a situation in which a quantity of the wire
is extruded such that
that the wire pushes into the plate and the amount of force remains constant.
In curve 1610, a
greater quantity of the wire is extruded and more force is detected as the
wire is pushed at a
higher force into the plate. Next, additional wire 1615 is extruded until the
force is sufficiently
high such that the wire slips in the preload system. When a peak force is
observed, the wire
undergoes a slipping action and subsequently settles to a lower force. FIG. 17
is an enlargement
between regions 4 and 5 on the x-axis of FIG 16.
Example 7
[00150] FIG. 18 illustrates signal from the process of filling a hole when
repairing a portion
of the 3D object. A hole may be formed in a piece of metal and the wire may be
directed toward
the hole. The wire may be heated over time and may melt as it hits the bottom
of the hole when
current passes through the wire. When the wire initially hits the bottom at
1805, it is a cold piece
of metal and a spike in the force occurs. Then, the force drops off quickly as
the wire melts.
Another few millimeters of wire may be extruded and repeated at various start
points 1810,
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WO 2020/033337 PCT/US2019/045177
1815, and 1820. The successive peaks 1810, 1815, and 1820 are smaller than the
first peak 1805
because following each deposition more molten metal develops and the metal
temperature
increases. Once the hole is filled, the deposition of molten wire ends as the
wire is pushing
against the hard metal, resulting in the largest spikes at 1825.
[00151] While preferred embodiments of the present invention have been shown
and
described herein, it will be obvious to those skilled in the art that such
embodiments are provided
by way of example only. It is not intended that the invention be limited by
the specific examples
provided within the specification. While the invention has been described with
reference to the
aforementioned specification, the descriptions and illustrations of the
embodiments herein are
not meant to be construed in a limiting sense. Numerous variations, changes,
and substitutions
will now occur to those skilled in the art without departing from the
invention. Furthermore, it
shall be understood that all aspects of the invention are not limited to the
specific depictions,
configurations or relative proportions set forth herein which depend upon a
variety of conditions
and variables. It should be understood that various alternatives to the
embodiments of the
invention described herein may be employed in practicing the invention. It is
therefore
contemplated that the invention shall also cover any such alternatives,
modifications, variations
or equivalents. It is intended that the following claims define the scope of
the invention and that
methods and structures within the scope of these claims and their equivalents
be covered thereby.
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