U.S. patent application number 17/088174 was filed with the patent office on 2021-02-18 for method and apparatus for support removal using directed atomized and semi-atomized fluid.
The applicant listed for this patent is PostProcess Technologies, Inc.. Invention is credited to Marc Farfaglia, Daniel Joshua Hutchinson.
Application Number | 20210046705 17/088174 |
Document ID | / |
Family ID | 1000005191161 |
Filed Date | 2021-02-18 |
United States Patent
Application |
20210046705 |
Kind Code |
A1 |
Hutchinson; Daniel Joshua ;
et al. |
February 18, 2021 |
Method And Apparatus For Support Removal Using Directed Atomized
And Semi-Atomized Fluid
Abstract
An apparatus and method for removing support material from
and/or smoothing surfaces of an additively manufactured part (the
"AM part") is disclosed. The apparatus may include a chamber, a
support surface within the chamber, and one or more nozzles within
the chamber. The nozzles may be the same size or different sizes.
The support surface may be configured to support the AM part. The
support surface may have one or more openings sized and configured
to allow the fluid to pass through the opening(s). The nozzles may
be configured to spray a fluid at the AM part, and the spray may be
an atomized or semi-atomized spray of the fluid.
Inventors: |
Hutchinson; Daniel Joshua;
(Orchard Park, NY) ; Farfaglia; Marc; (Buffalo,
NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
PostProcess Technologies, Inc. |
Buffalo |
NY |
US |
|
|
Family ID: |
1000005191161 |
Appl. No.: |
17/088174 |
Filed: |
November 3, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16232955 |
Dec 26, 2018 |
10850449 |
|
|
17088174 |
|
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62612483 |
Dec 31, 2017 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B29C 64/30 20170801;
B22F 10/00 20210101; B22F 2003/247 20130101; B29C 64/35 20170801;
B33Y 40/00 20141201; B22F 3/24 20130101; B22F 2003/241
20130101 |
International
Class: |
B29C 64/30 20060101
B29C064/30; B22F 3/24 20060101 B22F003/24; B33Y 40/00 20060101
B33Y040/00; B29C 64/35 20060101 B29C064/35 |
Claims
1. An apparatus for removing support material from and/or smoothing
surfaces of an additively manufactured part, comprising: a chamber;
a support surface within the chamber, and configured to support an
additively manufactured part (the "AM part"); and one or more
nozzles within the chamber, and configured for spraying a fluid at
said AM part, wherein said nozzles generate an atomized or
semi-atomized spray of said fluid.
2. The apparatus of claim 1, further comprising a tank configured
to hold a volume of said fluid, and positioned to capture the fluid
after the fluid is sprayed.
3. The apparatus of claim 2, further comprising a heater at least
partially within said tank for heating said fluid to a desired
temperature.
4. The apparatus of claim 1, wherein said support surface further
comprises openings sized and configured to allow said fluid to pass
through said one or more openings.
5. The apparatus of claim 1, wherein the nozzles are arranged as
two spray-headers of nozzles.
6. The apparatus of claim 5, further comprising: a first
spray-header of nozzles configured to spray said fluid
substantially downward toward the AM part; and a second
spray-header of nozzles configured to spray said fluid
substantially upward toward the AM part.
7. The apparatus of claim 6, wherein one or both of said first and
second spray-headers of nozzles is connected directly or indirectly
to an actuator for translating said spray-header of nozzles back
and forth in a planar motion.
8. The apparatus of claim 6, wherein one or both of said first and
second spray-headers of nozzles is secured to a mount that is
adjustable to move the spray-header nearer to or further away from
said support surface.
9. The apparatus of claim 8, wherein one or both of said first and
second spray-headers of nozzles is connected directly or indirectly
to an actuator for translating said spray-header of nozzles back
and forth in a planar motion.
10. The apparatus of claim 6, wherein nozzles of the first
spray-header of nozzles are of two or more sizes.
11. The apparatus of claim 10, wherein fluid can flow to spray
through first nozzles of one size at the same time that fluid
cannot flow to spray through second nozzles of a second size.
12. The apparatus of claim 6, wherein nozzles of the second
spray-header of nozzles are of two or more sizes.
13. The apparatus of claim 6, wherein nozzles of the first
spray-header of nozzles are of two or more sizes and nozzles of the
second spray-header of nozzles are of two or more sizes.
14. The apparatus of claim 13, wherein fluid can flow to spray
through first nozzles of one size at the same time that fluid
cannot flow to spray through second nozzles of a second size.
15. The apparatus of claim 14, wherein both of the first and second
nozzles are associated with the first spray-header of nozzles.
16. The apparatus of claim 14, wherein the first nozzles are
associated with the first spray-header of nozzles and the second
nozzles are associated with the second spray-header of nozzles.
17. The apparatus of claim 1, further comprising a blower for
forcing air into or pulling air out of the chamber.
18. The apparatus of claim 1, further comprising a vent for
allowing air to leave the chamber.
19. (canceled)
20. (canceled)
21. (canceled)
22. (canceled)
23. (canceled)
24. (canceled)
25. (canceled)
26. (canceled)
27. (canceled)
28. (canceled)
29. (canceled)
30. An apparatus for removing support material from or smoothing
surfaces of an additively manufactured part, comprising: a chamber;
a support surface within the chamber, and configured to support an
additively manufactured part; one or more nozzles within the
chamber, and configured for spraying a fluid at said AM part,
wherein said nozzles generate an atomized or semi-atomized spray of
said fluid; and an HMI adapted for selection of a desired level of
agitation by opening and closing valves to the one or more
nozzles.
31. An apparatus for removing support material from or smoothing
surfaces of an additively manufactured part, comprising: a chamber;
a support surface within the chamber, and configured to support an
additively manufactured part; one or more nozzles within the
chamber, and configured for spraying a fluid at said AM part,
wherein said nozzles generate an atomized or semi-atomized spray of
said fluid; and one or more sensors located at or near an inlet to
the one or more nozzles for monitoring pressure.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of priority to U.S.
provisional patent application Ser. No. 62/612,483, filed on Dec.
31, 2017, the entire disclosure of which is herein incorporated by
this reference.
FIELD OF THE INVENTION
[0002] This invention relates generally to a method and apparatus
for removing support material from parts that have been made via
additive manufacturing techniques, such as 3D printing.
BACKGROUND OF THE INVENTION
[0003] Additive manufacturing processes, such as 3D printing (e.g.
Selective Laser Sintering (SLS), Stereolithography (SLA), fused
deposition modeling (FDM), material jetting (MJ), electron beam
(e-beam), etc.) have enabled the production of parts having complex
geometries that would never be possible through traditional
manufacturing techniques, such as casting, injection molding, or
forging. However, additive manufacturing produces parts that
require significant efforts to remove unwanted support material.
The support material is needed during the manufacturing process to
support portions of the part as the part is being manufactured in
order to achieve complex geometries. After the manufacturing
process is completed, the unwanted support material must be removed
and/or rough surfaces may need to be smoothed.
[0004] The support material itself can have a complex geometry and
can also be extensive. Additionally, since additive manufacturing
manufactures a part in discrete layers, the surface of a part is
often rough, because adjacent layers may not end in similar
locations thereby leaving a rough bumpy outer surface. Such a rough
outer surface is unappealing from a visual standpoint, and the
uneven surface can create stress concentrations, which could
develop during testing or use of the part and lead to pre-mature
failure.
[0005] A current option in the additive manufacturing industry is
to manually remove the support material and manually finish the
surface of a part in order to produce a smooth exterior surface of
the part. Depending on the type of part, using manual labor could
be cost prohibitive, and could lead to excessive removal of
material, an uneven surface, or both. If a surface is finished
unevenly or incompletely, stress concentrations could still be
unintentionally prevalent, leading to pre-mature failure of the
part. In addition, manual removal of unwanted support material and
manual surface finishing lacks consistency over an extended period
of time and from part to part. And, such manual removal/finishing
may create a bottleneck in the production process since, for
example, one technician can remove support material from only a
single part at a time.
[0006] Another option the additive manufacturing industry is moving
toward is to use a machine, such as those providing a chemical
bath, to remove support material and/or to perform surface
finishing. However, such machines are limited in the type of
process parameters that can be altered to tailor the process to a
specific part, and also such machines require the attention of, and
operation by, a technician while the machine is running, which does
not completely eliminate the bottleneck issue described above.
Additionally, if a technician is unaware that a machine is not set
at the proper parameters, excessive material removal could occur,
ruining the part.
[0007] Thus, there is a need for a method and apparatus for
automatically removing support material from and smoothing the
surface of parts made via additive manufacturing techniques without
damaging the part itself. One such approach is to use embodiments
of the present invention, which use atomized and semi-atomized
fluid, chemical dissolution, and pressurized fluid. Additionally,
embodiments of the present invention may provide an alternative
that seeks to remove the manual labor bottleneck of processing
additive manufactured parts in order to achieve surface finishing
and/or support removal ("SF/SR").
SUMMARY OF THE INVENTION
[0008] The invention may be embodied as an apparatus for removing
support material from and/or smoothing surfaces of an additively
manufactured part (the "AM part"). The apparatus may include a
chamber, a support surface within the chamber, and one or more
nozzles within the chamber. The nozzles may be the same size or
different sizes.
[0009] The support surface may be configured to support the AM
part. The support surface may have one or more openings sized and
configured to allow the fluid to pass through the opening(s). For
example, the support surface may be a screen-like surface.
[0010] The nozzles may be configured to spray a fluid at the AM
part, and the spray may be an atomized or semi-atomized spray of
the fluid. The nozzles may be arranged in groups, each group being
part of a spray header that is fed from a common supply tube. The
nozzles of a particular spray-header may be the same size, but they
need not be the same size. For example, the nozzles of a particular
spray-header may be selected from two or more sizes.
[0011] The nozzles of one spray-header may be the same size as the
nozzles of another spray-header, but the nozzles of one
spray-header may be differently sized from the nozzles of another
spray-header. For example, with regard to two spray-headers the
nozzles of one spray-header may be selected to be of a first size,
and the nozzles of the other spray-header may be selected to be of
a second size.
[0012] In one embodiment of the invention, there are two
spray-headers of nozzles; one above the support surface (a.k.a.
"top spray-header) and one below the support surface (a.k.a.
"bottom spray-header"). The top spray-header may point the nozzles
to spray downward toward the AM part, and the bottom spray-header
may point the nozzles to spray upward toward the AM part.
[0013] One or more valves may be included in the apparatus so that
fluid can flow and spray through a first set of nozzles having one
size at the same time that fluid cannot flow to spray through
second nozzles of a second size. For example, nozzles of a
particular spray-header may be of two or more sizes, and fluid can
be made to flow through and to spray from first nozzles of one size
at the same time that fluid cannot flow to spray through second
nozzles of another size.
[0014] One or more of the spray-headers of nozzles may be secured
to a mount that is adjustable to move the spray-header(s) nearer to
or further away from the support surface. One or more of the
spray-headers of nozzles may be connected directly or indirectly to
an actuator for translating the spray-header(s) back and forth in a
planar motion.
[0015] The apparatus may also include a tank configured to hold a
volume of the fluid, and the tank may be positioned (e.g. in the
chamber) to capture the fluid after the fluid is sprayed.
[0016] The apparatus may also include a heater for heating the
fluid to a desired temperature. The heater may be at least
partially within the tank.
[0017] The apparatus may include a ventilation system. The
ventilation system may be a blower for forcing air into or pulling
air out of the chamber. The ventilation system may be a vent for
allowing air to leave or enter the chamber. The ventilation system
may include both such a blower and such a vent.
[0018] The invention may be embodied as a method of removing
support material from and/or smoothing surfaces of an AM part. Such
a method may include providing a chamber, a support surface within
the chamber, and one or more nozzles within the chamber. An AM part
may be placed on the support surface, and a fluid may be sprayed at
the AM part. The nozzles may generate an atomized or semi-atomized
spray of the fluid.
[0019] The nozzles may spray at the same velocity. However, in at
least one embodiment of a method according to the invention at
least one of the nozzles sprays the fluid at a velocity that is
different from the spray velocity created by a different one of the
nozzles.
[0020] The method may be carried out so that one (or more) of the
nozzles sprays the fluid at a first flow rate and one (or more) of
the nozzles sprays the fluid at a second flow rate. For example, in
one embodiment of a method that is in keeping with the invention a
first one (or more) of nozzles sprays the fluid at a first flow
rate and a second one (or more) of the nozzles sprays the fluid at
a second flow rate.
[0021] The method may be carried out in such a manner that a one
(or more) of the nozzles has a first size and one or more of the
nozzles has a second size, and a pressure at which the fluid is
supplied to the nozzles of the first size is different than a
pressure at which the fluid is supplied to the nozzles of the
second size.
[0022] A tank may be provided. The tank may be configured to hold a
volume of the fluid, and to capture the fluid in the tank after the
fluid is sprayed. Such a tank may be well suited to facilitating a
cycling of the fluid through the nozzles so that the same fluid may
be sprayed many times at the AM part.
[0023] A heater may be provided, and may be arranged in the tank.
The heater may be used to heat the fluid to a desired temperature.
The temperature of the fluid may be increased toward the desired
temperature while the AM part is sprayed.
[0024] Spraying of the fluid may occur from a first set of the
nozzles that is configured to spray the fluid substantially
downward toward the AM part, and also from a second set of the
nozzles that is configured to spray the fluid substantially upward
toward the AM part.
[0025] While spraying occurs, the nozzles may be translated. For
example, one or more sets of the nozzles may be translated during
spraying of the fluid.
[0026] Air may be blown into or pulled out of the chamber. This may
be done during spraying and/or after spraying.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] For a fuller understanding of the nature and objects of the
invention, reference should be made to the accompanying drawings
and the subsequent description. Briefly:
[0028] FIG. 1 is a schematic depiction of an apparatus that is in
keeping with the invention;
[0029] FIG. 2 is a schematic depiction of an additively
manufactured part;
[0030] FIG. 3A is a front view of an apparatus that is in keeping
with the invention;
[0031] FIG. 3B is a side view of the apparatus depicted in FIG.
3A;
[0032] FIG. 3C is a top view of the apparatus depicted in FIG.
3A;
[0033] FIG. 4 is a schematic depiction of an apparatus that is in
keeping with the invention;
[0034] FIG. 5 is a schematic depiction of an apparatus that is in
keeping with the invention; and
[0035] FIG. 6 is a flow diagram depicting a method that is in
keeping with the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0036] At the outset, it should be appreciated that like drawing
numbers on different drawing views identify identical, or
functionally similar, structural elements of the invention.
[0037] Furthermore, it is understood that this invention is not
limited to the particular methodology, materials, or modifications
described and, as such, the invention may vary from that which is
disclosed herein. It is also understood that the terminology used
herein is for the purpose of describing particular aspects, and
this invention is not limited to the disclosed aspects.
[0038] Unless defined otherwise, all technical and scientific terms
used herein have the same meaning as commonly understood to one of
ordinary skill in the art to which this invention pertains. It
should be understood that methods, devices or materials similar or
equivalent to those described herein can be used in the practice or
testing of the method and apparatus.
[0039] Furthermore, as used herein, "and/or" is intended to mean a
grammatical conjunction used to indicate that one or more of the
elements or conditions recited may be included or occur. For
example, a device comprising a first element, a second element
and/or a third element, is intended to be construed as any one of
the following structural arrangements: a device comprising a first
element; a device comprising a second element; a device comprising
a third element; a device comprising a first element and a second
element; a device comprising a first element and a third element; a
device comprising a first element, a second element and a third
element; or, a device comprising a second element and a third
element.
[0040] Adverting now to the figures, with specific reference in
FIGS. 1-2, the present invention may be embodied as a method or an
apparatus 8 for SF/SR. In such a method or apparatus 8, one or more
additive manufactured parts 10 needing SF/SR are placed on a
platform or tray 13 in a chamber 16 of an apparatus 8 for carrying
out SF/SR. An SF/SR fluid 22 for dissolving and/or eroding the
support material 28 may be sprayed at the part(s) 10 through
nozzles 25 situated underneath the part(s) 10 or above the part(s)
10 or both. The nozzles 25 below the part(s) 10 and the nozzles 25
above the part(s) 10 may be referred herein as bottom nozzles 25B
and top nozzles 25A, respectively. The fluid 22 may be supplied
from a tank 31, open at its upper side. The tank 31 may be situated
below the bottom nozzles 25. A pump 33 may be used to draw fluid 22
from the tank 31 and then force the fluid 22 through a series of
pipes 50 connected to the nozzles 25, which causes the fluid 22 to
spray out of the nozzles 25 at the part(s) 10. Each nozzle 25 may
comprise a pipe or tube section having multiple apertures or
nozzles through which the fluid 22 sprays, and these arrangements
are sometimes referenced herein, as a "spray-header". The fluid 22
then collects back into the tank 31 where the fluid 22 is recycled
back through the apparatus, i.e., drawn from the tank 31, forced to
the nozzles 25, sprayed at the parts 10, and collected in the tank
31. In this mode of operation the apparatus 8 may be a closed-loop
system.
[0041] Additive manufactured parts 10 may be made using numerous
different methods, classes of materials (e.g., plastics, metals),
specific build materials (e.g., nylon within the plastics class,
aluminum within the metals class) and support materials. Each
method, class of material, and specific build material can have its
own unique qualities and characteristics and thus may require
different parameters for effective and efficient removal of support
material 28. Additionally, for a given type, parts 10 made by such
an additive manufacturing process and/or materials may have very
different geometries, including designs having more delicate
features than others, which thus may require adjustments for
effective and efficient removal of support material 28. As
explained in more detail herein, the amount of fluid 22 sprayed,
the direction of spray (from top and/or bottom), the location of
spray (e.g., left versus right side of part or top versus bottom
side of part), the pressure at which fluid 22 is pumped to the
nozzles 25, and the degree of atomization, as well as other
parameters such as the make-up, temperature and pH of the fluid,
can be adjusted to create different combinations or "recipes" of
these parameters in order to efficiently and effectively remove a
given type of support material 28 for a given type of build
material 35 and geometric design of additive manufactured part(s)
10. In some embodiments of the present invention, an operator can
set or change these parameters using a human-machine interface
("HMI") 38, such as a touch screen 108 connected to a
general-purpose computer having a central processing unit ("CPU")
102. The general-purpose computer may have wired or wireless
communications links 105 for sending and receiving communications
signals to/from components of the apparatus 8.
[0042] The fluid 22 is capable of dissolving and/or degrading
support material 28, and may be aqueous-based chemical formulations
made with a single chemical or a variety of chemicals. The fluid 22
may, in some embodiments, be referred to as a detergent.
Preferably, the fluid 22, either naturally or aided by the
parameter settings, degrades or dissolves support material 28 and
the rough surface of the part 10 without also degrading, dissolving
or causing damage to the build material 35 of the part 10 that is
intended to be preserved. Such fluids 22 can include but are not
limited to those fluids that are optimized for SF/SR for parts 10
made by MJ, SLA and FDM, respectively. The fluid 22 can also
include an anti-foaming agent to help minimize foaming of the fluid
during the SF/SR process.
[0043] An embodiment of the present invention may be an apparatus 8
having a housing 41 comprising a first section 44, a second section
47 arranged adjacent to said first section 44, as illustrated in
FIGS. 1, 3A, 3B, and 3C. The first section 44 may include a chamber
16 where the SF/SR of an additive manufactured part 10 occurs. The
second section 47 may house many of the plumbing components for the
apparatus 8, such as a pump 33, valves 59, and hoses 62. The second
section 47 can be arranged either below or to the side of the first
section 44.
[0044] The first section 44 may include a door 68 for an operator
to access the chamber, and place parts 10 into and remove them from
the chamber 16. The door 68 can be a counter-weighted balanced door
to allow for easy access. As discussed further below, the chamber
16 may heat up during the apparatus' operation. The chamber 16 can
include a ventilation or exhaust system to provide a heated
equalized chamber 16 to aid both in the removal of support material
28 as well as enhancing the evaporation of residual fluid 22 off of
the part 10 upon completion of the SF/SR process. A ventilation
system may be of any type suitable for venting heat and vapors that
can build up in the chamber 16. As one example, the ventilation
system may comprise one or more blowers 75 pulling air from the
chamber 16, such as blowers rated, for example, at 0.5 to 1000
cubic feet per minute (CFM). In this approach the ventilation
system may create a negative pressure in the chamber 16 so that
when the door 68 is opened, air is pulled inward through the door
68. In another example, the ventilation system may comprise one or
more fans or blowers 75 pushing air into the chamber 16, combined
with a chimney or other exhaust mechanism 78 in the roof of the
chamber 16. The fan or blower 75 may create a positive pressure in
the chamber 16 and the chimney 78 allows excess heat and vapors to
escape. Additionally, windows 81 may be placed in the sides of the
chamber 16 to allow for in-process monitoring by humans and sensors
of the SF/SR process.
[0045] A tray or platform 13 on which the parts 10 can be set while
an SF/SR process occurs may be situated in the chamber 16. A first
plurality of nozzles 25 (such as the top nozzles 25A) may be
arranged in the chamber 16, allowing for fluid 22 to be sprayed
downward toward the parts 10 situated on the tray 13. A second
plurality of nozzles 25 (such as the bottom nozzles 25B) may be
arranged in the chamber 16, directly below the tray 13, allowing
for fluid 22 to be sprayed upward toward the parts 10 situated on
the tray 13. The bottom nozzles 25B and top nozzles 25A are thus
arranged opposite from each other, spraying in directions toward
each other, with the parts 10 situated therebetween. The first
section 44 also may include a tank 31 for holding the fluid 22. The
tank 31 may be situated below the bottom nozzles 25B.
[0046] The tray 13 may have openings of suitable size, quantity and
distribution, such as a mesh screen, so that the tray 13 can
support the parts 10, yet allow fluid 22 to be sprayed at the parts
10 from the bottom nozzles 25B, allow fluid 22 sprayed from both
the bottom and top nozzles 25B, 25A to flow down into the tank 31,
and help to prevent support material 28 that detaches from the part
10 from falling down into the tank 31. A mesh screen 53 may be
arranged between the tank 31 and the bottom nozzles 25B to further
prevent pieces of detached support material 28 from entering the
tank 31.
[0047] In one embodiment of the invention, a first plurality of
nozzles 25 comprises a single spray-header of nozzles 25, and in
another embodiment of the invention the first plurality of nozzles
25 comprises more than a single spray-header of nozzles 25, such as
three spray-headers of top nozzles 25A. The size of the apertures
or nozzles in one spray-header of nozzles 25 can be different from
the size of the apertures or nozzles in another spray-header,
thereby resulting in different fluid velocities spraying from the
two different sets of nozzles 25, with one velocity being higher
than the other. For example, in the embodiment with three sets of
top nozzle spray-headers 25A, the first and third sets can each
comprise five apertures/nozzles of the same or similar size (or
degree of spray angle), while the second set can comprise three
apertures/nozzles of a larger size (or degree of spray angle). The
top nozzles 25A can be either mounted to the housing 41 itself, or
mounted on a movable track 42 connected to an actuator 43 that
allows the nozzles 25 to oscillate in the horizontal direction. The
second plurality of nozzles 25 can be identical to the first
plurality of nozzles 25 mounted on a movable track 42 that is
connected to an actuator 43, or can be stationary nozzles 25 that
cannot move independently on a track. In one embodiment, the second
plurality of nozzles 25 comprises a spray-header having thirteen
nozzles 25 each of the same or similar size (or degree of spray
angle).
[0048] In another embodiment of the invention, nozzles 25 could be
arranged to surround the chamber 16 so that the nozzles 25 are on
all six sides surrounding the part 10 in the chamber 16. Each
nozzle 25 can be independently controlled by a separate motor or be
connected as a nozzle assembly. In this embodiment there are
nozzles 25 mounted both horizontally and vertically.
[0049] FIG. 4 depicts a further embodiment of the invention in
which the bottom nozzles 25B are arranged as a U-shaped
spray-header. As with the embodiment mentioned directly above, the
nozzles 25 may spray the AM part 25 from different directions and
thereby spray additional sides of the AM part 25 more directly. In
a similar manner, the top spray-header of nozzles 25A may be
U-shaped. Or, both the top spray-header of nozzles 25A and the
bottom spray-header of nozzles 25B may be U-shaped.
[0050] Servomotors or other actuators may be used to oscillate a
spray-header of nozzles 25 through a range of distance about a
center point. Interface and control buttons may enable an operator
to adjust the location of the center point (by causing the
spray-header of nozzles 25 to move forward or backward) and/or the
speed at which the nozzles 25 oscillate. For example, the center
point could be set anywhere between a range of 0-275 millimeters
and the speed could be set anywhere between a range of 0-50 mm/sec.
Or, these parameters may be pre-stored in connection with an
operating recipe that the operator has the option to select. In one
embodiment of the invention the operator can also adjust the
distance that the nozzles 25 oscillate. The movement of each nozzle
25 may be tracked by a position sensor. The first plurality of
nozzles 25 could be made to oscillate only if at least one of the
valves 59 to a nozzle contained in the first plurality of nozzle 25
is open. In such an embodiment, if only the second plurality of
nozzles 25 is activated, then the first plurality of nozzles 25
does not oscillate.
[0051] The nozzles 25 can be individual nozzles 25, or can be
tubes/piping having a plurality of apertures therein, e.g. a
manifold (each such aperture is also referred to as a "nozzle"), or
could include nozzles 25 secured to the tubes/piping. Additionally,
the individual nozzles 25, including individual nozzles secured to
the tubes/piping, may be constructed to rotate independently, using
motors, in order to spray parts 10 within the chamber 16 at a
variety of angles. Each nozzle 25 may be independently controlled
by a separate motor or be connected to each other so as to form a
nozzle assembly. Additionally, each nozzle 25 could be controlled
by a multi-axis robot. The nozzles 25 may be made to move in
horizontal and/or vertical directions. It should be appreciated
that each nozzle 25 may be connected to its own pump and plumbing
system.
[0052] Both the first and second plurality of nozzles 25 (e.g., top
and bottom nozzles 25A, 25B) may be connected to a pump 33, which
may be located within the second section 47 of the housing 41.
After drawing fluid 22 from the tank 31, the pump 33 can force the
fluid 22 through pipes 50 (which may be a flexible hose) to the
nozzles 25. A manifold may be used to separate the fluid 22 output
from the pump 33 into separate supplies for each spray-header of
nozzles 25. The individual pipe 50 to each spray-header of nozzles
25 may include a valve 59 to control the flow of fluid 22 to the
nozzles 25. This arrangement allows nozzles 25 to be used
selectively (on/of), thereby increasing efficiency where all of the
nozzles 25 are not required for SF/SR and/or where it is preferred
to have some nozzles 25 at higher or lower pressures than
others.
[0053] For example, an embodiment of the invention may have one
bottom spray-header of nozzles 25 and three top spray-headers of
nozzles 25, where at least one of the top spray-headers has
narrow-angle nozzles 25 (producing comparatively higher velocity
spray) and at least one of the other top spray-headers has
wide-angle nozzles 25 (producing comparatively lower velocity
spray). In each of the following examples, the valve 59 controlling
flow to the bottom spray-header of nozzles 25 may always be open.
In one mode of operation, all of the valves 59 controlling flow to
the top nozzles 25 can be closed so that fluid 22 sprays only from
the bottom spray-header 25B. This mode can produce the lowest
degree of agitation of the additively manufactured parts 10 being
SF/SR processed in the chamber 16, and may be referred to as
"ultra-low agitation." In another mode of operation the valve(s) 59
controlling flow to the top spray-header(s) 25A having wide-angle
nozzles 25 may be open, but the valve(s) 59 controlling flow to the
top spray-header(s) 25A having narrow-angle nozzles 25 may be
closed. This mode can produce a higher degree of agitation than
where only the bottom nozzles 25B are used, and may be referred to
as "low agitation." In yet another mode of operation, the valve(s)
59 controlling flow to the top spray-header(s) 25A having
wide-angle nozzles 25 may be open and the valve 59 controlling flow
to one (but not more than one) top spray-header having narrow-angle
nozzles 25 may be open. This mode can produce a higher degree of
agitation than the prior example, and may be referred to as "medium
agitation." In yet a further mode of operation, the valve(s) 59
controlling flow to the top spray-header(s) 25A having narrow-angle
nozzles 25 may be open but the valve(s) 59 controlling flow to the
top spray-header(s) 25 have wide-angle nozzles 25 may be closed.
This mode can produce the highest level of agitation, and may be
referred to as "high agitation." Other arrangements of
spray-headers, varying sizes of nozzles 25, and open versus closed
valves 59 may be used to create additional variations in the levels
of agitation. Thus, the use of terms such as "low," "medium" and
"high" are not meant to be limited to the precise arrangements
described in the foregoing examples, but rather to exemplify that
various, relative degrees of agitation can be accomplished as
desired to meet specific needs.
[0054] An operator can use the HMI 38 to select a desired level of
agitation, or the agitation level may be pre-stored in connection
with a given operating recipe that the operator has the option to
select. By setting the agitation level, the apparatus 8
automatically opens and closes the valves 59 to the nozzles 25 as
appropriate to achieve that selected level of agitation. These
parameters can be set individually or by selecting a pre-stored
recipe.
[0055] The pressure of the fluid 22 pumped through the system may
be a function of a variety of factors including the action of the
pump 33, the length, sizing and configuration of the plumbing
between the pump 33 and the nozzles 25, and the sizes and quantity
of nozzles 25. The apparatus 8 may have one or more sensors 65C
located at or near the inlet to each valve 59 leading to each
spray-header of nozzles 25, or at another suitable location, for
measuring and monitoring the pressure of the fluid 22 being forced
to the nozzles 25. This pressure can be, for example, from 0.01 psi
to 100 psi. During operation, the pressure can change for a variety
of reasons, and the apparatus 8 may include sensors 65C for
measuring the pressure. The apparatus may alert the operator if the
pressure begins to decrease or increase from the level expected, or
initially achieved, for a given set of SF/SR processing parameters,
and also may alert the operator if the pressure drops below or
exceeds minimum and maximum levels, respectively. These minimum and
maximum levels can be pre-programmed into the apparatus 8.
Additionally, if these minimum or maximum pressure levels are
exceeded, the apparatus 8 can automatically shut down.
[0056] An embodiment of the invention may simultaneously achieve a
high rate of fluid flow through the nozzles 25, such as 5 to 150
gallons per minute, and a low pressure at which the fluid 22 is
provided to the nozzles 25, such as 15-30 psi. The speed at which
support material is removed may be aided by having as much flow of
fluid 22 on the part 10 as possible, while protecting the build
material 35 of the part 10 from erosion by maintaining the fluid
velocity below a desired level. The nozzle aperture sizes (and/or
spray angles), quantities of nozzles 25 and specifications for the
pump 33 and plumbing may be selected to achieve these multiple
goals. Additionally, oscillating the nozzles 25 changes the
direction and speed of the spray exiting the nozzles 25, which
provides an additional opportunity for modulating both the force of
the fluid 22 impacting the parts 10 as well as the area covered by
that fluid 22. For example, oscillating the nozzles 25 at a higher
speed may result in a lower average force at which the fluid 22
impacts the additive manufactured parts 10 and a wider coverage
area within the chamber 16.
[0057] In another embodiment of the invention as illustrated in
FIG. 5, a wider chamber 16 is used and there are two systems of top
and bottom nozzles 25, arranged adjacent to each other, effectively
defining first processing region 87 and second processing region 90
within the chamber 16. In this embodiment, fluid 22 is delivered to
the first processing region 87 by the first top nozzles 25A1 and
first bottom nozzles 25B1, and fluid 22 is delivered to the second
processing region 90 by the second top nozzles 25A2 and second
bottom nozzles 25B2. In this embodiment, the tank 31 situated below
the bottom nozzles 25B can be a single tank 31 spanning the two
regions 87, 90. A first pump 33A can be connected to the first top
and first bottom nozzles 25A1, 25B1, and a second pump 33B can be
connected to the second top and second bottom nozzles 25A2, 25B2.
In this embodiment, the pumps 33, valves 59, spray-headers of
nozzles 25, and all of the various settings relating thereto can be
set and operated in the two regions 87, 90 independently.
[0058] This embodiment enables the apparatus 8 to have different
flow rates, pressures and spray velocities (i.e., agitation levels)
as between the two regions 87, 90. This can be useful in several
ways. For example, some additive manufactured parts 10 are long and
have more support material 28 and/or surface areas of build
material 35 toward one end of the part 10 ("heavy end") versus the
opposite end ("light end"). If the same flow, pressure levels and
spray velocities were applied across the entire part 10, then
either the light end would be at risk for over-processing (which
might include degradation or warping of the part 10) or the heavy
end of the part 10 would be at risk for under-processing (leaving
too much support material 28 or un-smoothed surfaces of build
material 35 remaining on the part 10). By having two independent
SF/SR processing regions 87, 90, the part 10 can be situated in the
chamber 16 so that the end with more support material 28 and/or
surface areas of build material 35 lies in the region that has
higher flow, pressure and spray velocity, while the other end of
the part 10 with less support material 28 and/or surfaces areas of
build material 35 lies in the region that has lower flow, pressure
and spray velocity. This protects the second end of the part 10
from over-processing and the first end of the part 10 from
under-processing. Another advantage of having two regions is that a
given part 10 may have more support material near its bottom area
than near its top area. A quantity of these parts 10 could be
simultaneously SF/SR processed with a portion of the quantity
oriented upright in one region and the other portion oriented
upside down in the other region, with each region having flow of
fluid 22 and pressure appropriate for those orientations of the
parts.
[0059] In an embodiment where nozzles are configured to oscillate
during a SF/SR process, a motion-monitoring sensor can be used to
detect which of the nozzles 25 are moving during the SF/SR process.
The apparatus 8 may frequently monitor the position of the nozzles
25 and if no motion is detected, the apparatus 8 may attempt to
reset the motor controlling movement of the nozzles 25. If a reset
of the motor is unsuccessful, then the HMI 38 may alert a user and
pause the SF/SR process since the apparatus 8 may not be operating
properly. The detection of nozzle movement may be done via an
encoder arranged on each motor or by other suitable means.
[0060] The tank 31 may be filled automatically with fluid 22 based
on parameters set by the operator or as may be pre-stored in
connection with a given operating recipe that the operator has the
option to select. To this end, the apparatus 8 may include devices
for supplying each of water, support material solvent (also
referred to as detergent), and anti-foaming agent supplies. Water
may be supplied from a facility's water supply 19 or from a
reservoir or other storage tank. Solvent and anti-foaming agent may
be supplied each from their own reservoir or storage tank, such as
a 5-gallon bucket 56 connected to the apparatus by a hose 62 or
other conduit. The hose 62 for each of the solvent and anti-foaming
agent may be connected to a mechanism, such as a water-powered
pump, for automatically dispensing such fluids into the tank.
[0061] A liquid level sensor 65D may be situated in the tank 31 to
detect the level of the fluid 22 in the tank 31, thereby enabling a
determination of when the fluid 22 filling the tank 31 reaches the
maximum level, at which point the sensor 65D sends a signal that is
interpreted and results in the filling to automatically stop. The
sensor 65D also may be employed to enable detection of when the
fluid 22 drops below a desired level during operation, which can
happen for example as fluids evaporate, and may send a signal that
is interpreted and may result in alerting the operator to use the
interface to cause more fluids to be dosed into the tank (which
dosing again stops automatically if the maximum fill level is
reached). Alternatively, programming could be provided to cause
this dosing to occur automatically.
[0062] Use of this auto-dose feature ensures that enough fluid 22
is arranged in the apparatus 8 for the SF/SR process to run
properly. When an apparatus 8 runs for an extended period of time
at high temperatures, the fluid 22 used in the SF/SR process
evaporates. Also, amounts of fluid 22 may adhere to interior
surfaces of chamber 16 and to surfaces of components within chamber
16. In order to ensure that enough fluid 22 remains in the system,
a configurable desired fluid level may be set in the software of
the apparatus 8, and the fluid level in the tank 31 may be detected
using a liquid level sensor 65D such as a floating sensor to detect
the liquid level. If the liquid level falls below the desired
level, the apparatus 8 could react by supplying additional amounts
of one or more components of the fluid 22 (e.g., water, solvent,
anti-foaming agent) into the tank 31. Additionally, a configurable
time interval could be set by a user for checking the liquid level
during the SF/SR process. At the end of a configurable time
interval, the SF/SR process may pause for an amount of time (for
example, 30 seconds) in order to let foam that may have formed in
the tank 31 to settle. Once the settling time has elapsed, a liquid
level measurement may be taken. If the liquid level has not
attained the desired level, the apparatus 8 may automatically add
fluid to the tank 31 and in order to fill the tank 31 up to the
desired liquid level.
[0063] A heater 96, such as an immersion heater, and a sensor 65B
for measuring temperature, may be situated in or in connection with
the tank 31. Additionally, a pH sensor 65A may be situated in or in
connection with the tank 31. The heater 96 may be used to heat the
fluid 22 to a desired temperature and, based on feedback from the
temperature sensor 65B, to maintain the fluid 22 at that
temperature. The heater 96 may be used to heat the fluid 22 to a
desired temperature within an allowable range, such as for example,
85.degree. F. to 160.degree. F., or another process-suitable range.
The fluid 22 in the tank 31 may be heated to the desired
temperature prior to starting the SF/SR process to spray the parts
10, or the fluid 22 can be used before it is heated at all or when
it is only partially heated to the desired temperature. In this
latter approach, the SF/SR process begins with the fluid 22 at a
low temperature and, as time elapses during the SF/SR process, the
heater 96 operates to increase the temperature of the fluid 22 to
the desired level. The approach of gradually increasing the
temperature of the fluid 22 can aid in the removal of support
material 28. This is because the fluid 22 can usually remove
support material 28 over a range of temperatures. Thus, by engaging
in SF/SR as the fluid temperature rises, the fluid 22 can begin to
remove support material 28 as the fluid 22 reaches the lowest
temperature suitable for removing support material 28 and then
remove the support material 28 more rapidly as the fluid approaches
the final desired temperature. In this manner, the build material
35 of the part 10 will not heat up as much as compared to the case
where the fluid 22 is at the highest temperature from the start of
the SF/SR process. This helps to protect the build material 35 of
the part 10 from degradation, such as warping.
[0064] The pH sensor 65A can detect the pH of the fluid 22, which
at the outset can be a reflection of the combination of liquids
forming the fluid 22 (e.g., solvent, water and, if used,
anti-foaming agent) and may be used while filling the tank 31 to
achieve the desired pH. The pH can change during the apparatus' 8
operation, for example due to dissolved support material 28
contaminating the fluid 22 or due to evaporation of portions of the
fluid 22. The pH sensor 65A may be used to detect such changes and
to alert the operator when the pH drops below or exceeds a desired
level, whereupon the operator may use the HMI 38 to cause dosing of
fluids as needed to adjust the pH to the desired level. For
example, if the pH is too high (i.e., too basic), then more solvent
can be added. But if the pH is too low (i.e., too acidic), then
more water can be added. Alternatively, the apparatus 8 may be
configured to automatically dose fluids as needed to adjust the pH.
The desired temperature and pH may be set by the operator using the
HMI 38, or may be pre-stored in connection with a given operating
recipe that the operator has the option to select.
[0065] As the fluid 22 flows through the apparatus 8, its
temperature can change, which may be undesirable. In particular, it
is important to maintain the fluid 22 at the desired temperature as
it travels from the tank 31 to the nozzles 25. Yet, many pumps 33
heat up while they are operating and transfer that heat to the
fluid 22 as it moves through the pump 33. In embodiments of the
present invention, it is preferable to use a pump 33 that adds
minimal heat to the fluid 22, such as a magnetically coupled pump
33.
[0066] Atomization of the fluid 22 by spraying it through
appropriately sized nozzles 25, where the fluid 22 separates into
small droplets while also spreading out in a flat fan, hollow cone,
or full cone spray pattern helps to control the force at which
fluid 22 impacts the part 10 while maximizing flow of the fluid 22.
The top nozzles 25A may be further away from the parts 10 being
SF/SR processed than the bottom nozzles 25B, and in such a
configuration, the force of the spray from the top nozzles 25A as
it impacts the parts 10 can sometimes fall below a desired amount.
The design of the bottom nozzles 25B can help with this. The spray
from the bottom nozzles 25B may have enough force to hit the bottom
of the parts 10 and then continue to travel upwards to heights
above the parts 10. There, the droplets combine with each other
and/or droplets from the top nozzles 25A into larger droplets,
whereupon these larger droplets fall down onto the parts 10. Aided
by both gravity and the force of the drops from the top spray
nozzles 25A, these larger particles may hit the parts 10 with more
flow and kinetic energy than drops coming from the top nozzles 25A
alone or the bottom nozzles 25B alone. Nonetheless, the top nozzles
25A may be mounted in a way so as to be adjustable closer to or
further away from the parts 10. Likewise, the location of the parts
10 may be adjustable such that parts 10 are set further away from
the bottom nozzles 25B and thus closer to the top nozzles 25A, or
vice-versa.
[0067] The fluid 22 in the tank 31 may be drained automatically. At
the end of each SF/SR process, there may be the option to drain all
the fluid 22 from the tank 31 and replace it with new fluid 22.
This option may be pre-set by the operator or selected by the
operator upon the completion of an SF/SR process. An auto-drain
feature may also be used to drain the tank 31 after a prescribed
number of SF/SR processes, which may be set by the operator.
[0068] After the tank 31 is drained, the tank 31 may be
automatically filled with clean water, and used for rinsing the
part 10 in order to remove fluid 22 remaining on the part 10. The
water may be heated in the same manner as the fluid 22. When
selecting the parameters for the SF/SR process, the operator may
set the temperature for the rinsing water or select the temperature
from a pre-stored recipe. In one embodiment, the fluid 22 for
removing support material 28 may be automatically drained from the
tank 31 after the designated run time and replaced with clean water
(using the same auto-fill mechanisms described above), which is
then cycled through the apparatus 8 to rinse the parts 10, at the
same agitation level setting as used during the support removal
portion of the SF/SR process. During this rinsing process, the
water may be pre-heated to the desired temperature or the
temperature may be gradually raised while the apparatus is
running.
[0069] During the SF/SR process, heat from the fluid 22 in the tank
31 can heat up air in the chamber 16. This heated air in the
chamber helps, in turn, to maintain the fluid 22 at the desired
temperature while fluid 22 is sprayed from the nozzles 25 and
collects back into the tank 31. At the end of a SF/SR and/or rinse
cycle, the heater 96 in the tank 31 may be kept operating to
maintain the heat in the chamber 16, which, in turn, may be useful
for drying the parts 10 prior to removing them from the chamber 16.
When carried out in this manner, an SF/SR process may be said to be
a "dry-to-dry" process: that is the parts 10 placed in the chamber
16 are dry and do not require preparation work to be done on them
prior to the SF/SR process, and the parts 10 come out of the
chamber 16 dry after the SF/SR process is complete.
[0070] Operation. A method according to the present invention,
illustrated in FIG. 6, may comprise the following of steps to
remove support material 28 and/or finish a surface of build
material 35 of a part 10 and rinse residual material from a part 10
made using additive manufacturing. The operator may use 200 the HM
38 to cause the tank 31 to fill with fluid 22. The operator also
may use the HMI 38 to set other SF/SR processing parameters for the
additive manufactured parts 10 to be SF/SR processed, including
temperature (of both the support removal and rinsing fluids), pH of
the fluid 22, the length of run time (in hours and minutes),
agitation level (e.g., ultra-low, low, medium or high agitation),
center-point position of the top spray-header(s) of nozzles 25, the
range of distance through which the top nozzles 25A oscillate, and
the speed of oscillation of the top nozzles 25A. Additionally, the
operator may place 203 one or more additive manufactured parts 10
on the tray 13 within the chamber 16. The heater 96 in the tank 31
may operate to heat the fluid 22, which in turn helps to heat the
air in the chamber 16. The fluid 22 can be brought to full
temperature prior to starting the SF/SR process, or gradually after
the SF/SR process begins.
[0071] Next, the pump(s) 33 may activate, drawing fluid 22 from the
tank 31, through the pump(s) 33, and then forcing 206 the fluid 22
through the manifold (if used) and those of the open valves 59
toward and through the nozzles 25 associated with the open valves
59 in order to spray the fluid 22. The upper nozzles 25A may
oscillate when the associated valves 59 are open and allow fluid 22
to flow to the nozzles 25A, and those nozzles 25A may rotate or
otherwise move in accordance with the selected settings. The fluid
22 then exits the nozzles 25 as atomized and/or semi-atomized fluid
22 and collides with the part 10, including the support material
28, whereupon the support material 28 begins to dissolve or
otherwise separate from the part 10 and/or rough surfaces of build
material 35 of the part begin to smooth. The fluid 22 then passes
through the openings in the tray 13 and collects 209 in the tank 31
located under the bottom nozzles 25B, whereupon the fluid 22 cycles
206 through the nozzles 25 again as the pump 33 continues to draw
fluid 22 from tank 31. This cycling 212 of the fluid 22 continues
for the duration of the run time set by the operator or until the
operator manually stops the SF/SR process.
[0072] During the SF/SR process, the apparatus 8 may measure the
fluid level in the tank 31 to ensure enough fluid 22 is contained
in the tank 31. If there is not enough fluid 22 in the tank 31
(e.g., due to evaporation) the apparatus 8 may add fluid 22
components, such as the water, solvent and/or anti-foaming agent as
appropriate. The apparatus 8 also may measure the pH of the fluid
22 and dose the tank 31 with water and/or solvent as needed to
maintain the desired pH level.
[0073] After the prescribed amount of time, the spraying stops, the
fluid 22 may automatically drain 215 from the tank 31, the tank 31
may automatically fill 215 with clean water, and then the spraying
may re-start to rinse the parts 10. The water may be cycled 218
through the system until a prescribed amount of time has elapsed,
the rinsing process stops, and the parts 10 may remain in the
chamber 16 for drying by the heated air in the chamber 16.
[0074] The ventilation system may operate during the SF/SR process
to safely exhaust excess vapors and thus prevent them from escaping
out of the chamber 16 to areas that could pose a threat to users
standing around the apparatus 8 while the SF/SR process is
occurring. The ventilation system may be kept running for a time
interval (for example, 5 minutes) after an SF/SR process is
completed.
[0075] The method may be carried out so as to determine the
agitation level in concert with optimal temperature in order to
maximize the speed and efficiency of SF/SR processing. When the
fluid 22 is too cool, the support material 28 may not be removed as
efficiently, but when the fluid is too hot, the part can experience
damage such as shape degradation, including warpage. Additionally,
as will be appreciated by the disclosure herein, the hardware,
electronics, software and fluid 22 may work together to provide
desired levels of efficacy and efficiency, from delicate support
removal to more robust removal with higher throughput.
[0076] Settable parameters can be different and/or customized for
particular build and support materials 35, 28 out of which the
additive manufactured parts 10 are made, the part geometries
including the geometries of support structures, and the degree and
speed of support material removal desired. Balancing and varying
these parameters increases the efficacy and efficiency at which
support material 28 can be removed. The apparatus 8 can be
pre-programmed at a factory with "recipes" of the parameter
settings known to be suitable for various support and build
materials 28, 35, part geometries, etc. Thus, by a single
activation operation, e.g. pressing one button or a short sequence
of buttons, the operator may be able to set all of the parameters
for a given SF/SR process. Additionally, the operator can set
parameters and save them as a recipe, which the operator can then
select in the future rather than re-inputting each of the
settings.
[0077] The present invention may further include a logic controller
99 to monitor communication between a central processing unit
("CPU") 102 and the HMI 38. In such an embodiment of the invention,
a signal may be sent from the HMI 38 to the CPU 102, and
vice-versa. The logic controller 99 may monitor this signal to make
sure the signal changes during the SF/SR process. If the signal
stops, the logic controller 99 may react by either shutting down
the apparatus 8, or the HMI 38 will inform the operator to restart
the apparatus 8. The HMI 38 and CPU 102 may be connected to the
Internet in order to be operated and evaluated remotely.
Additionally, this Internet connection could enable the use of a
database that contains a plurality of test parameters and
additional recipes that may be used to optimize the SF/SR and rinse
processes. The database may alternatively be contained on a hard
drive that may be associated with the apparatus 8 itself and be
uploaded periodically to a remotely located storage device.
[0078] The apparatus 8 may collect and store data about settings
and about how the apparatus 8 should or does operate, which can be
used to service the apparatus 8 and as feedback for improving SF/SR
settings for various types of support and build materials 28, 35
and part geometries.
[0079] In the foregoing description, example embodiments are
described. The specification and drawings are accordingly to be
regarded in an illustrative rather than a restrictive sense.
[0080] It will be appreciated that various aspects of the
above-disclosed invention and other features and functions, or
alternatives thereof, may be desirably combined into many other
different systems or applications. Various presently unforeseen or
unanticipated alternatives, modifications, variations, and/or
improvements therein may be subsequently made by those skilled in
the art, and those alternatives, modifications, variations, and/or
improvements are intended to be encompassed by the following
claims.
[0081] Although the present invention has been described with
respect to one or more particular embodiments, it will be
understood that other embodiments of the present invention may be
made without departing from the spirit and scope of the present
invention. Hence, the present invention is deemed limited only by
the appended claims and the reasonable interpretation thereof.
* * * * *