U.S. patent application number 16/412883 was filed with the patent office on 2019-08-29 for additive manufacturing system with heater configured for improved interlayer adhesion in a part formed by the system.
The applicant listed for this patent is Xerox Corporation. Invention is credited to Barry P. Mandel, David A. Mantell, Paul J. McConville, Peter J. Nystrom.
Application Number | 20190263066 16/412883 |
Document ID | / |
Family ID | 60328950 |
Filed Date | 2019-08-29 |
United States Patent
Application |
20190263066 |
Kind Code |
A1 |
Nystrom; Peter J. ; et
al. |
August 29, 2019 |
ADDITIVE MANUFACTURING SYSTEM WITH HEATER CONFIGURED FOR IMPROVED
INTERLAYER ADHESION IN A PART FORMED BY THE SYSTEM
Abstract
A three-dimensional object printing system improves the
interlayer adhesion of an object. The printing system includes a
platform on which a three-dimensional object is built. A material
applicator in the printing system expels material to form layers of
the object on the platform. The material applicator also includes a
heater mounted to an arm that is configured to rotate about the
material applicator to position the heater so the heater heats the
layer of the object ahead of the material applicator as the
material applicator moves relative to the platform.
Inventors: |
Nystrom; Peter J.; (Webster,
NY) ; Mandel; Barry P.; (Fairport, NY) ;
Mantell; David A.; (Rochester, NY) ; McConville; Paul
J.; (Webster, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Xerox Corporation |
Norwalk |
CT |
US |
|
|
Family ID: |
60328950 |
Appl. No.: |
16/412883 |
Filed: |
May 15, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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15156366 |
May 17, 2016 |
10328637 |
|
|
16412883 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B29C 64/295 20170801;
B29C 64/393 20170801; B29C 64/245 20170801; B29C 64/118 20170801;
B29K 2101/12 20130101; B33Y 10/00 20141201; B33Y 30/00 20141201;
B33Y 50/02 20141201; B29C 64/40 20170801 |
International
Class: |
B29C 64/295 20060101
B29C064/295; B29C 64/40 20060101 B29C064/40; B29C 64/393 20060101
B29C064/393; B29C 64/118 20060101 B29C064/118 |
Claims
1. A three-dimensional (3D) object manufacturing system comprising:
a platform defining a planar surface; a material applicator
configured to expel material to form a layer of an object on the
platform; a first actuator operatively connected to one of the
platform and the material applicator to move the platform and
material applicator relative to one another in at least a first
direction and a second direction that are orthogonal to one another
in a plane that is parallel to the planar surface; and a heater
mounted to an arm that is configured to rotate about the material
applicator to position the heater relative to the material
applicator so the heater heats a portion of the layer of the object
before the material applicator expels material onto the portion of
the layer of the object as the material applicator moves in the
first and second directions.
2. The 3D object manufacturing system of claim 1 wherein the heater
is further configured to heat the expelled material ahead of the
material applicator to a temperature greater than a transition
temperature of the material forming the object on the platform but
less than a temperature at which the material becomes liquid.
3. The 3D object manufacturing system of claim 2 further
comprising: a second actuator operatively connected to the arm to
which the heater is mounted, the actuator being configured to
rotate the arm about the material applicator.
4. The 3D object manufacturing system of claim 3 further
comprising: a controller operatively connected to the first
actuator and the second actuator, the controller being configured
to operate the second actuator to rotate the arm and position the
heater to lead the material applicator as the material application
moves relative to the platform.
5. The 3D object manufacturing system of claim 4 wherein the
controller is further configured to adjust an electrical power
delivered to the heater with reference to a speed at which the
material applicator moves.
6. The 3D object manufacturing system of claim 4 wherein the
controller is further configured to adjust an electrical power
delivered to the heater with reference to a size of an area over
which the material applicator moves while expelling material.
7. The 3D object manufacturing system of claim 4 wherein the
controller is further configured to adjust an electrical power
delivered to the heater with reference to an elapsed time since the
heater heated the area in which the material applicator is
expelling material.
8. The 3D object manufacturing system of claim 4 further
comprising: a sensor for generating a signal indicative of a
temperature of an area opposite the sensor, the sensor being
mounted proximate to the heater; and the controller is operatively
connected to the sensor, the controller being further configured to
adjust an electrical power delivered to the heater with reference
to the temperature indicated by the signal received from the
sensor.
9. The 3D object manufacturing system of claim 8 wherein the sensor
is mounted to precede the heater as the material applicator moves
relative to the platform.
10. The 3D object manufacturing system of claim 9 wherein the
sensor is an infrared thermocouple.
11. The 3D object manufacturing system of claim 4 wherein the
material applicator is an extruder.
12. The 3D object manufacturing system of claim 4 wherein the
material applicator is a printhead.
13. The 3D object manufacturing system of claim 4 wherein the
heater is a single heating element.
14. The 3D object manufacturing system of claim 14, the heater
further comprising: a source of pressurized air positioned to
direct air heated by the single heating element away from the
heating element.
15. The 3D object manufacturing system of claim 4, the material
applicator further comprising: a heater within the material
applicator to heat material to be expelled from the material
applicator to a transition temperature of the material before
expelling the material.
16. A three-dimensional (3D) object manufacturing system
comprising: a platform defining a planar surface; a material
applicator configured to expel material to form a layer of an
object on the platform; a first actuator operatively connected to
one of the platform and the material applicator to move the
platform and material applicator relative to one another in at
least a first direction and a second direction that are orthogonal
to one another in a plane that is parallel to the planar surface; a
heater mounted to an arm that is configured to rotate about the
material applicator to position the heater relative to the material
applicator so the heater heats a portion of the layer of the object
before the material applicator expels material onto the portion of
the layer of the object as the material applicator moves in the
first and second directions, the heater being further configured to
heat the expelled material ahead of the material applicator to a
temperature greater than a transition temperature of the material
forming the object on the platform but less than a temperature at
which the material becomes liquid; and a second actuator
operatively connected to the arm to which the heater is mounted,
the actuator being configured to rotate the arm about the material
applicator.
17. The 3D object manufacturing system of claim 16 further
comprising: a controller operatively connected to the first
actuator and the second actuator, the controller being configured
to operate the second actuator to rotate the arm and position the
heater to lead the material applicator as the material application
moves relative to the platform.
18. The 3D object manufacturing system of claim 17 wherein the
controller is further configured to adjust an electrical power
delivered to the heater with reference to a speed at which the
material applicator moves.
19. The 3D object manufacturing system of claim 18 further
comprising: a sensor for generating a signal indicative of a
temperature of an area opposite the sensor, the sensor being
mounted proximate to the heater; and the controller is operatively
connected to the sensor, the controller being further configured to
adjust an electrical power delivered to the heater with reference
to the temperature indicated by the signal received from the
sensor.
20. The 3D object manufacturing system of claim 19, the material
applicator further comprising: a heater within the material
applicator to heat material to be expelled from the material
applicator to a transition temperature of the material before
expelling the material.
Description
PRIORITY CLAIM
[0001] This application is a divisional application of co-pending
U.S. patent application Ser. No. 15/156,366, which is entitled
"Improved Interlayer Adhesion In A Part Printed By Additive
Manufacturing," which was filed on May 17, 2016, and which issued
as U.S. Pat. No. ______ on ______.
TECHNICAL FIELD
[0002] The system and method disclosed in this document relate to
printers that produce three-dimensional objects and, more
particularly, to a device and method for improving interlayer
adhesion in parts printed by such printers.
BACKGROUND
[0003] Digital three-dimensional manufacturing, also known as
digital additive manufacturing, is a process of making a
three-dimensional solid object of virtually any shape from a
digital data model. Three-dimensional printing is distinguishable
from traditional object-forming techniques, which mostly rely on
the removal of material from a work piece by a subtractive process,
such as cutting or drilling. Fused Filament Fabrication (FFF)
printing, for example, is an additive process in which one or more
material applicators extrude polymer filament to form successive
layers of material on a substrate in different shapes. In some
embodiments, the polymer filament includes fillers, such as metal
particles or fibers, or the polymer filament comprises a metal wire
coated with a polymer.
[0004] The polymer filament is typically unwound from a coil and
fed into the material applicator to provide material for a layer.
As described in further detail below, in the material applicator,
the filament is heated to a temperature that increases the
pliability of the material, enabling the material to be extruded
selectively through a nozzle onto the platform at a controlled
rate. The substrate is typically supported on a platform, and one
or more material applicators are operatively connected to one or
more actuators for controlled movement of the one or more material
applicators relative to the platform to produce the layers that
form the object. The material applicators are typically moved
vertically and horizontally relative to the platform via a
numerically controlled mechanism to position the nozzle at x-, y-,
and z-dimension coordinates before depositing the material on the
substrate. In alternative embodiments, the platform is moved
relative to the material applicators.
[0005] One process for producing three-dimensional objects with a
FFF printing system 10 is illustrated in FIGS. 6A-6D. As shown in
FIG. 6A, during a printing operation, at least one material
applicator 14 is positioned relative to a member 18 to space the at
least one material applicator 14 vertically above the member 18 in
the z-dimension by a height H. As the at least one material
applicator 14 is driven in the x-dimension relative to the member
18, the at least one material applicator 14 deposits a layer 22 of
material 26 having a length L (shown in FIG. 6B) on the member
18.
[0006] The material 26 is fed into the at least one material
applicator 14 as a filament 38 that is heated by a melter 42 of the
at least one material applicator 14. As mentioned above, the melter
42 heats the filament 38 to a temperature that increases the
pliability of the polymer of the filament material 26. Typically,
the polymer of the filament material 26 is a thermoplastic, which
is a material that is pliable above a certain temperature, referred
to hereinafter as a "transition temperature," and acts as a solid
below the transition temperature. Furthermore, some thermoplastics
have an amorphous crystal structure, which prevents the material
from "solidifying," or forming a crystalline structure, even below
the transition temperature.
[0007] When the melter 42 heats the thermoplastic polymer of the
filament material 26 above the transition temperature, the
intermolecular forces of the material 26 weaken, and the material
26 becomes more pliable and less viscous. At this elevated
temperature, the material 26 is selectively extrudable and is
hereinafter referred to as being "extrudable" or in "an extrudable
state." The melter 42 does not heat the filament 38 to a
temperature which causes the material 26 to become completely
liquid and run. Instead, the melter 42 heats the filament 38 to a
temperature above the transition temperature at which the material
26 is soft and malleable, but not completely liquid. After being
heated by the melter 42, the extrudable material 26 is deposited on
the member 18 by a nozzle 46 of the at least one material
applicator 14. After being deposited by the nozzle 46, the material
26 cools on the member 18 to a temperature below the transition
temperature such that the layer 22 becomes less pliable and more
viscous and acts as a solid.
[0008] As shown in FIG. 6B, after the layer 22 of material 26 is
deposited on the member 18, the at least one material applicator 14
is driven in the z-dimension relative to the member 18 to
re-position the at least one material applicator 14 at the height H
above the layer 22. Re-positioning the at least one material
applicator 14 in the z-dimension accommodates the thickness T of
the layer 22 atop the member 18 to prevent the at least one
material applicator 14 from contacting the layer 22 during
subsequent passes in the x-dimension. After re-positioning in the
z-dimension, the at least one material applicator 14 is again
driven in the x-dimension to deposit another layer 30 of the object
34 on top of the layer 22. The at least one material applicator 14
can be driven in the x-dimension to pass the member 18 in the same
direction or in the opposite direction as the previous pass. If the
at least one material applicator 14 is driven in the same
direction, the at least one material applicator 14 is also
re-positioned in the x-dimension before depositing the further
layer 30.
[0009] As shown in FIGS. 6C and 6D, the at least one material
applicator 14 is also driven in the y-dimension in the same manner
as described above with respect to the x-dimension. Accordingly,
the at least one material applicator 14 also deposits material 26
to define a width W of the object 34 on the member 18. The at least
one material applicator 14 can define the width W of the object 34
either by depositing the material 26 on the member 18 in layers
with each layer having the width W in the y-dimension (shown in
FIG. 6C) or by depositing multiple layers on the member 18 in the
x-dimension to make up the width W in the y-dimension (shown in
FIG. 6D). In some printing systems, the at least one material
applicator 14 can be driven in a direction having components in
both the x-dimension and the y-dimension. Since the
three-dimensional object printing process is an additive process,
material 26 is repeatedly added to the object 34, and the thickness
T of the object 34 increases throughout the process. This process
can be repeated as many times as necessary to form the object
34.
[0010] One issue that arises in the production of three-dimensional
objects with a FFF printing system is the possibility of
inconsistent material strength throughout the object. In
particular, objects may have inconsistent material strength in the
height along the z-dimension. This inconsistency may arise due to
weak bonding between the layers of material forming the object,
resulting in low and inconsistent interlayer strength throughout
the object. A printing system that builds the layers with stronger
adhesion between layers would be beneficial.
SUMMARY
[0011] A three-dimensional object printing system includes a
platform, a material applicator, and a heater. The platform defines
a planar surface, and the material applicator and the platform are
configured to move relative to one another in at least a first
direction and a second direction. The first direction and the
second direction are parallel to the planar surface. The material
applicator is configured to expel material to form a layer of an
object on the platform. The heater is coupled to the material
applicator and is configured to heat a portion of the layer before
the material applicator expels material onto the portion of the
layer when the material applicator moves in the first and second
directions. The heater is configured to heat the layer to a
temperature greater than a transition temperature of the material
forming the object on the platform.
[0012] A method of printing an object in a three-dimensional
printing system includes expelling material from a material
applicator to form a layer of an object on a platform positioned
opposite the material applicator. The method further includes
moving the material applicator in at least a first direction and a
second direction. The first direction and the second direction are
parallel to a planar surface of the platform. The method also
includes heating a first portion of the layer ahead of the material
applicator to a temperature greater than a transition temperature
of the material forming the object on the platform when the
material applicator is moving in the first direction. The method
also includes heating a second portion of the layer ahead of the
material applicator to the temperature greater than the transition
temperature of the material forming the object on the platform when
the material applicator is moving in the second direction.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The foregoing aspects and other features of a
three-dimensional object printer and method for forming an object
with the printer to correct for inconsistent interlayer strength of
the object are explained in the following description, taken in
connection with the accompanying drawings.
[0014] FIG. 1A shows a side view of a printing system including a
material applicator and a heater.
[0015] FIG. 1B shows a top view of a part of the printing system of
FIG. 1A.
[0016] FIG. 2 shows a top view of the printing system of FIG. 1A
including a temperature measuring device.
[0017] FIG. 3 shows a top view of another alternative embodiment of
a heater for use with the printing system of FIG. 1A.
[0018] FIG. 4 shows a top view of another alternative embodiment of
a heater for use with the printing system of FIG. 1A.
[0019] FIG. 5A shows a top view of another alternative embodiment
of a heater for use with the printing system of FIG. 1A.
[0020] FIG. 5B shows a side view of the heater of FIG. 5A for use
with the printing system of FIG. 1A.
[0021] FIG. 6A shows a top view of a prior art three-dimensional
object printer prior to performing a first portion of a process to
form an object.
[0022] FIG. 6B shows a top view of the prior art three-dimensional
object printer of FIG. 6A after a first portion of the process to
form the object has been completed.
[0023] FIG. 6C shows a side view of the prior art three-dimensional
object printer of FIG. 6A after a second portion of the process to
form the object has been completed.
[0024] FIG. 6D shows a side view of the prior art three-dimensional
object printer of FIG. 6A after a third portion of the process to
form the object has been completed.
DETAILED DESCRIPTION
[0025] For a general understanding of the environment for the
system and method disclosed herein as well as the details for the
system and method, reference is made to the drawings. In the
drawings, like reference numerals have been used throughout to
designate like elements.
[0026] A three-dimensional object printing system 100 is shown in
FIGS. 1A and 1B. The printing system 100 operates in a manner that
is similar to the operation of the printing system 10 described
above and shown in FIGS. 6A-6D. Like the prior art printing system
10, the printing system 100 includes a substrate or a member 104
having a planar surface 108 and at least one material applicator
112 configured to deposit material 116 on the planar surface 108
and subsequently formed layers. The printing system 100 differs
from the prior art printing system 10, however, in that the
printing system 100 also includes a heater 120 coupled to the
material applicator 112 and configured to heat material 116
previously deposited on the planar surface 108 and subsequently
formed layers.
[0027] As shown in FIG. 1A, the printing system 100 further
includes a controller 118 and an actuator 122, and the material
applicator 112 includes at least one melter 128 and at least one
nozzle 132. The actuator 122 is operatively connected to the
material applicator 112 and to the heater 120. The controller 118
is operatively connected to the actuator 122 to operate the
actuator 122 to selectively move the material applicator 112
relative to the member 104, to selectively heat material 116 within
the melter 128, to selectively expel material 116 from the nozzle
132, and to selectively heat the heater 120. It is noted that the
actuator 122 can be embodied as more than one actuator operatively
connected to the same controller or to different controllers. For
example, the actuator 122 can include one actuator configured to
selectively move the material applicator 112 relative to the member
104, one actuator configured to selectively heat material 116
within the melter 128, one actuator configured to selectively expel
material 116 from the nozzle 132, and another actuator configured
to selectively heat the heater 120.
[0028] As shown in FIG. 1A, like the printing system 10, the
printing system 100 is also a FFF printing system. The melter 128
receives a filament 130 of the material 116, and the actuator 122
selectively heats the filament 130 to a temperature above the
transition temperature of the material 116 to bring the material
116 to its extrudable state. The extrudable material 116 is
delivered to the nozzle 132, which has an orifice 134 that faces
toward the member 104. The actuator 122 selectively expels the
material 116 through the orifice 134 and onto the planar surface
108 of the member 104 or onto a previously formed layer to build an
object 136. To enable this building of the object, the actuator 122
also positions the material applicator 112 at a location above the
member 104 that enables the nozzle 132 and the material applicator
112 to pass over the object 136 and the member 104 without
contacting the object 136 or the member 104.
[0029] In alternative embodiments, the printing system 100 can be
another type of additive printing system. For example, the nozzle
132 can be replaced with another material expulsion element, such
as a printhead, and the melter 128 can be replaced with another
melting element configured to receive material 116 from a source,
heat the material to its extrudable state, and deliver the
extrudable material to the printhead. The printhead can include an
ejector, which, like the nozzle 132, is configured to deposit the
extrudable material 116 on the planar surface 108 of the member
104.
[0030] As shown in FIGS. 1A and 1B, as in the printing system 10,
the material applicator 112 of the printing system 100 is movable
in the x-, y-, and z-dimensions. In the same manner, the
z-dimension (shown in FIG. 1A) is perpendicular to the planar
surface 108 of the member 104, the x-dimension (shown in FIGS. 1A
and 1B) is parallel to the planar surface 108 of the member 104,
and the y-dimension (shown in FIG. 1B) is parallel to the planar
surface 108 of the member 104.
[0031] The controller 118 is configured to operate the actuator 122
(shown in FIG. 1A) to selectively move the material applicator 112
in the x-, y-, and z-dimensions and to selectively expel the
material 116 from the nozzle 132 of the material applicator 112.
The material applicator 112 is movable in at least a first
direction and a second direction in the x- and y-dimensions, each
of the first direction and the second direction being parallel to
the planar surface 108. The first direction and the second
direction can be opposite directions along a common line. For
example, as shown in FIG. 1B, the material applicator 112 is
movable rightwardly and leftwardly, or back and forth, along a
common line in the x-dimension. However, the first direction and
the second direction can also be directions that are not opposite
along a common line. For example, as shown in FIG. 1B, the material
applicator 112 is movable leftwardly and rightwardly, in directions
in the x-dimension, and upwardly and downwardly, in directions the
y-dimension. These directions are not opposite along a common line.
Furthermore, in some embodiments, the material applicator 112 is
also movable in directions that have components in both the
x-dimension and the y-dimension. For example, as shown in FIG. 1B,
the material applicator 112 is movable diagonally in directions
having an upward or downward component and having a leftward or
rightward component.
[0032] The actuator 122 moves the material applicator 112 in the
first and second directions without changing the orientation of the
material applicator 112. In other words, the material applicator
112 does not rotate about a longitudinal axis 140 (shown in FIG.
1B) of the material applicator 112, which extends in the
z-dimension. In alternative embodiments, however, the material
applicator 112 may be rotatable about the longitudinal axis
140.
[0033] The heater 120 is coupled to the material applicator 112 in
such a way that the heater 120 does not interfere with the filament
130 being fed into the material applicator 112, the melter 128, the
nozzle 132, or the extrudable material 116 being extruded from the
nozzle 132. The heater 120 is further arranged to direct heat
toward the planar surface 108 of the member 104. Accordingly, when
the object 136 is present on the member 104, the heater 120 directs
heat toward an uppermost layer 144 of the object 136. Like the
material applicator 112, the heater 120 is also configured to heat
the material 116 to a temperature above the transition temperature
of the material 116. Thus, the heater 120 weakens the
intermolecular bonds of the material 116 on the uppermost layer 144
of the object 136.
[0034] The controller 118 operates the actuator 122 to selectively
heat the heater 120 to heat the material 116 above its transition
temperature. More specifically, the heater 120 increases the
pliability and reduces the viscosity of the material 116, but does
not heat the material 116 to a temperature at which it becomes
completely liquid. Because the material 116 is not heated to a
temperature at which it becomes completely liquid and runs, the
object 136 is not significantly distorted or deformed by the heat
from the heater 120.
[0035] In at least one embodiment, the controller 118 operates the
actuator 122 to adjust the power of the heater 120 based on the
speed of movement of the material applicator 112. Accordingly, when
the material applicator 112 moves more slowly, the power of the
heater 120 is adjusted to heat the uppermost layer 144 of the
object 136 more slowly to prevent overheating the uppermost layer
144. In contrast, when the material applicator 112 moves more
quickly, the power of the heater 120 is adjusted to heat the
uppermost layer 144 of the object 136 more quickly to sufficiently
heat the uppermost layer 144 to a temperature above the transition
temperature of the material 116.
[0036] Similarly, the controller 118 could be configured to operate
the actuator 122 to adjust the power of the heater 120 based on the
duration of movements of the material applicator 112. Accordingly,
when the material applicator 112 makes small movements and remains
above a small area of the object 136, the power of the heater 120
is adjusted to heat the uppermost layer 144 of the object 136 more
slowly to prevent overheating the smaller area of the uppermost
layer 144. In contrast, when the material applicator 112 makes
large movements and moves above a large area of the object 136, the
power of the heater 120 is adjusted to heat the uppermost layer 144
of the object 136 more quickly to sufficiently heat the larger area
of the uppermost layer 144 to a temperature above the transition
temperature of the material 116.
[0037] Additionally, the controller 118 could be configured to
operate the actuator 122 to adjust the power of the heater 120
based on an elapsed time since the heater 120 last heated an area
of material 116. If the heater 120 has recently heated an area of
the object 136, the material 116 in that area may still be above
the transition temperature and may not benefit from additional
heating or may become overheated. Accordingly, the controller 118
could be configured to obtain data from the model of the object 136
being printed to determine how recently an area of the object 136
was heated and adjust the power of the heater 120 to direct less
heat to areas that were more recently heated. When the material
applicator 112 is moved to an area that it has recently heated, the
power of the heater 120 is adjusted to heat the uppermost layer 144
of the object 136 more slowly to prevent overheating the recently
heated area of the uppermost layer 144. In contrast, when the
material applicator 112 is moved to an area that has not been
recently heated, the power of the heater 120 is adjusted to heat
the uppermost layer 144 of the object 136 more quickly to
sufficiently heat the less recently heated area of the uppermost
layer to a temperature above the transition temperature of the
material 116.
[0038] Additionally, or alternatively, the printing system 100 can
include a temperature measuring device, for example an infrared
thermocouple 150, as shown in FIG. 2, operatively connected to the
controller 118. In such embodiments, the controller 118 is
configured to operate the actuator 122 to adjust the power of the
heater 120 based on a measured temperature of the object 136
received from the infrared thermocouple 150. It is noted that the
infrared thermocouple 150 can be embodied as more than one infrared
thermocouple operatively connected to the same controller or to
different controllers. The infrared thermocouple 150 is positioned
so as to be always ahead of the heater 120 to measure the
temperature of the object 136 at a position ahead of the position
of the heater 120 and the material applicator 112. The infrared
thermocouple 150 measures a temperature at the surface of an area
of the object 136 and transmits the temperature measurement
information to the controller 118. The controller 118 is configured
to adjust the power of the heater 120 based on the temperature
measurement information received from the infrared thermocouple
150.
[0039] For example, if the controller 118 receives temperature
measurement information from the infrared thermocouple 150
indicating a temperature at the surface of an area of the object
136 that is at or above the transition temperature, the material
116 in that area may not benefit from additional heating or may
become overheated. Accordingly, the power of the heater 120 is
adjusted to direct no heat toward that area of the object 136. If
the controller 118 receives temperature measurement information
from the infrared thermocouple 150 indicating a temperature at the
surface of an area of the object 136 that is below the transition
temperature, the power of the heater 120 is adjusted to direct
sufficient heat toward that area of the object 136 to raise the
temperature of the surface of that area of the object 136 to the
transition temperature of the material 116. In various embodiments,
the controller 118 can use temperature measurement information from
the infrared thermocouple 150 independently or in conjunction with
elapsed time and object model data to adjust the power of the
heater 120.
[0040] FIGS. 1A and 1B, the heater 120 is coupled to the material
applicator 112 so as to be always ahead of the material applicator
112 when the material applicator 112 moves in both the first
direction and the second direction. For example, when the material
applicator 112 moves in a direction of movement, indicated by the
arrow A in FIG. 1A, relative to the member 104, the heater 120 is
always positioned in front of the nozzle 132 of the material
applicator 112 in the direction of movement.
[0041] Accordingly, the heater 120 is configured to heat the
uppermost layer 144 of the object 136 before the material
applicator 112 applies another layer 148 atop the uppermost layer
144. Because the uppermost layer 144 is heated above the transition
temperature by the heater 120 and the next layer 148 is heated
above the transition temperature by the melter 128 before being
extruded through the nozzle 132, both are made up of material 116
that has weakened intermolecular bonds. The weakened intermolecular
bonds of the material 116 enable the material 116 of the uppermost
layer 144 and of the next layer 148 to intermingle upon contact. In
particular, polymer strands of the polymer of the material 116 at
the interface between the uppermost layer 144 and the next layer
148 rearrange and interact with one another. When the material 116
cools below its transition temperature, the intermingled material
116 of the uppermost layer 144 and the further layer 148 improves
the interlayer strength of the object 136.
[0042] As mentioned above, the actuator 122 maintains the
rotational position of the material applicator 112 relative to the
longitudinal axis 140 when moving the material applicator 112 in
the first direction and the second direction. Therefore, to
maintain its position in front of the nozzle 132, the heater 120 is
either rotated about the material applicator 112 or is positioned
to surround the material applicator 112. In the embodiment shown in
FIGS. 1A and 1B, the heater 120 includes a hot wire 152 within a
reflector 156 (shown in FIG. 1A). The reflector 156 is configured
to direct the heat generated by the hot wire 152 toward the planar
surface 108 of the member 104.
[0043] The heater 120 encircles the material applicator 112, and
the hot wire 152 and the reflector 156 are arranged parallel to the
planar surface 108. Thus, when the material applicator 112 moves in
the first direction parallel to the planar surface 108, the hot
wire 152 and the reflector 156 are positioned in front of the
nozzle 132. Additionally, when the material applicator 112 moves in
the second direction parallel to the planar surface 108, the hot
wire 152 and the reflector 156 are still positioned in front of the
nozzle 132. Because the heater 120 encircles the material
applicator 112, no matter in which direction the material
applicator 112 moves parallel to the planar surface 108, the heater
120 is positioned to lead the material applicator 112. In this
embodiment, hot wire 152 and the reflector 156 are also positioned
behind the nozzle 132.
[0044] As shown in FIG. 1B, from a top view, in a plane parallel to
the planar surface 108, the material applicator 112 defines a
perimeter 160. In the embodiment shown, the perimeter 160 is
circular. However, in alternative embodiments, the perimeter 160
can have other shapes. In the embodiment shown in FIGS. 1A and 1B,
the heater 120 is substantially cylindrically shaped and defines a
central axis 162 that is coaxial with the longitudinal axis 140 of
the material applicator 112. Thus, the heater 120 is positioned
concentrically about the material applicator 112. As shown in FIG.
1B, from the top view, the heater 120 completely surrounds the
material applicator 112. In other embodiments, the heater 120 can
have other shapes and can be positioned to completely surround the
material applicator 112, but have the central axis 162 not
coaxially located with the longitudinal axis 140.
[0045] FIG. 3 depicts a top view of an alternative embodiment of a
heater 120' for use with the printing system 100. The heater 120'
is substantially similar in structure and function to the heater
120 shown in FIGS. 1A and 1B and described above. However, the
heater 120' does not include a hot wire and a reflector. Instead,
the heater 120' includes separate heating elements 164 positioned
around the material applicator 112. In this embodiment, the
actuator 122 is configured to selectively heat the separate heating
elements 164 based on the direction of movement of the material
applicator 112. As shown in FIG. 3, when the material applicator
112 moves in a direction indicated by the arrow A in the
x-dimension, the actuator 122 selectively operates only the heating
elements 164 positioned along the direction A. Thus, the heating
elements 164 that are heated by the actuator 122 heat the uppermost
layer 144 of material 116 in front of and behind the nozzle 132. In
this embodiment, the heater 120' does not expend energy to emit
heat from portions of the heater 120' which are not arranged in
front of and behind the nozzle 132 in the direction of
movement.
[0046] FIG. 4 depicts a top view of another alternative embodiment
of a heater 120'' for use with the printing system 100. The heater
120'' is substantially similar in structure and function to the
heater 120 shown in FIGS. 1A and 1B and described above. However,
the heater 120'' does not include a hot wire and a reflector.
Instead, the heater 120'' includes a single heating element 168
which is rotatable about the material applicator 112. The heater
120'' also includes a motor 172 configured to selectively rotate
the single heating element 168 based on the direction of movement
of the material applicator. In this embodiment, the actuator 122 is
operatively coupled to the motor 172 to enable the motor 172 to
selectively rotate the single heating element 168. As shown in FIG.
4, when the material applicator 112 moves in a direction indicated
by the arrow B in the x-dimension and the y-dimension, the motor
172 rotates the single heating element 168 from an initial position
(indicated by dashed lines) to a position aligned with the
direction B. Thus, the single heating element 168 is selectively
positioned to heat the uppermost layer 144 of material 116 in front
of the nozzle 132. In this embodiment, the heater 120'' only
expends energy to emit heat from a single heating element 168 in
the direction of movement B.
[0047] FIGS. 5A and 5B depict a top view and a side view,
respectively, of another alternative embodiment of a heater 120'''
for use with the printing system 100. The heater 120''' is
substantially similar in structure and function to the heater 120
shown in FIGS. 1A and 1B and described above. However, the heater
120''' does not include a hot wire and a reflector. Instead, the
heater 120''' includes a heating element 174, a pressurized air
source, such as a fan or blower 176, a duct 180, (each shown in
FIG. 5A) and a heat distributor 184. In this embodiment, as shown
in FIG. 5A, the actuator 122 is operatively connected to the
heating element 174 and the fan or blower 176 and is configured to
heat the heating element 174 and actuate the fan or blower 176. The
duct 180 is coupled to the heating element 174 and to the heat
distributor 184, and the fan or blower 176 is actuated to blow hot
air generated by the heating element 174 into and through the duct
180 to the heat distributor 184. The hot air is then expelled from
the heat distributor 184 around the material applicator 112 to heat
the uppermost layer 144 of material 116. In the embodiment shown,
the heat distributor 184 is substantially cylindrically shaped and
surrounds the material applicator 112. Because, like the embodiment
of the heater 120 shown in FIGS. 1A and 1B, the heater 120''' emits
heat in every direction in a circle around the material applicator
112, when the material applicator 112 is moved in any direction
parallel to the planar surface 108, the heater 120''' heats the
uppermost layer 144 of material 116 in front of and behind the
nozzle 132. An additional advantage of the heater 120''' is that
the hot air generated by the heating element 174 can also carry
moisture away from the uppermost layer 144 of the object 136, which
may further aid in adhesion of the further layer 148 (shown in FIG.
5B) to the uppermost layer 144.
[0048] The heaters 120, 120', 120'', and 120''' are given only as
examples of heaters that can be used with the printing system 100.
Further alternative embodiments can include other types of heaters
and arrangements of heaters to emit heat toward the planar surface
108 of the member 104 in other ways not specifically discussed
herein. For example, in alternative embodiments, the printing
system 100 can include other heaters that use a hot radiant metal
filament, a ceramic heating element, and/or a heated flow of air to
heat the material 116. Additionally, the printing system 100 can
include other heaters that use other elements and/or procedures to
heat the material 116.
[0049] In all embodiments, the heater is configured to heat the
uppermost layer 144 ahead of the material applicator 112 when the
material applicator 112 moves in a first direction and moves in a
second direction to a temperature above the transition temperature
of the material to enable the material 116 of a further layer 148,
extruded from the nozzle 132 of the material applicator 112 atop
the uppermost layer 144, to intermingle with the heated material
116 of the uppermost layer 144.
[0050] It will be appreciated that variants of the above-disclosed
and other features and functions, or alternatives thereof, may be
desirably combined into many other different systems, applications
or methods. Various presently unforeseen or unanticipated
alternatives, modifications, variations, or improvements therein
may be subsequently made by those skilled in the art, which are
also intended to be encompassed by the following claims.
* * * * *