U.S. patent application number 15/341098 was filed with the patent office on 2017-03-16 for fabricated article.
The applicant listed for this patent is GENERAL ELECTRIC COMPANY. Invention is credited to David Vincent BUCCI, Yan CUI, Xiaoxue DIAO, Srikanth Chandrudu KOTTILINGAM, Dechao LIN.
Application Number | 20170074514 15/341098 |
Document ID | / |
Family ID | 52101100 |
Filed Date | 2017-03-16 |
United States Patent
Application |
20170074514 |
Kind Code |
A1 |
LIN; Dechao ; et
al. |
March 16, 2017 |
FABRICATED ARTICLE
Abstract
A fabricated article includes a substrate and one or more
turbulators formed on the substrate. Each of the one or more
turbulators includes at least one root portion providing a concave
transition between the substrate and the turbulator. In some
embodiments, the fabricated article is formed by a turbulator
fabrication process. The turbulator fabrication process includes
concurrently directing the first fusion energy toward a first side
of the turbulator material extending from the substrate and the
second fusion energy toward a second side of the turbulator
material opposite the first side and extending from the substrate.
The directing of the first fusion energy and the second fusion
energy shapes the first side of the turbulator material to have a
first contour and the second side of the turbulator material to
have a second contour, thereby forming the one or more turbulators
on the substrate.
Inventors: |
LIN; Dechao; (Greer, SC)
; KOTTILINGAM; Srikanth Chandrudu; (Simpsonville, SC)
; CUI; Yan; (Greer, SC) ; BUCCI; David
Vincent; (Simpsonville, SC) ; DIAO; Xiaoxue;
(Greenville, SC) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GENERAL ELECTRIC COMPANY |
Schenectady |
NY |
US |
|
|
Family ID: |
52101100 |
Appl. No.: |
15/341098 |
Filed: |
November 2, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
14104363 |
Dec 12, 2013 |
9511447 |
|
|
15341098 |
|
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B23K 26/342 20151001;
B23P 15/008 20130101; F23R 2900/00018 20130101; F23R 3/005
20130101; F23R 2900/03045 20130101; B23K 2103/52 20180801; B23K
26/144 20151001; F23R 3/16 20130101; B23K 2101/001 20180801; B23K
2103/16 20180801; B23K 2103/02 20180801; B23K 26/32 20130101; Y10T
29/49323 20150115; B23K 26/354 20151001; B23K 26/0608 20130101;
F23R 3/002 20130101; B23K 2103/08 20180801; B23K 2103/26 20180801;
F23R 3/44 20130101; B23K 26/3584 20180801 |
International
Class: |
F23R 3/16 20060101
F23R003/16; F23R 3/00 20060101 F23R003/00; B23K 26/144 20060101
B23K026/144; B23K 26/342 20060101 B23K026/342; B23K 26/00 20060101
B23K026/00; B23K 26/06 20060101 B23K026/06 |
Claims
1. A fabricated article, comprising: a substrate; and one or more
turbulators formed on the substrate; wherein each of the one or
more turbulators includes at least one root portion providing a
concave transition between the substrate and the turbulator.
2. The fabricated article of claim 1, wherein the at least one root
portion forms at least a 90 degree angle between the substrate and
the turbulator.
3. The fabricated article of claim 1, wherein the at least one root
portion is raised from the substrate to form at least a portion of
the turbulator.
4. The fabricated article of claim 1, wherein the substrate is a
portion of a combustion liner.
5. The fabricated article of claim 4, wherein at least one of the
one or more turbulators extends around the combustion liner.
6. The fabricated article of claim 4, wherein the one or more
turbulators comprises a plurality of continuous linear turbulators
on an exterior surface of the combustor liner.
7. The fabricated article of claim 1, wherein each turbulator
extends from the substrate with a first root portion of the at
least one root portion proximal to the substrate providing the
concave transition between the substrate and a first side of a
convex region of the turbulator.
8. The fabricated article of claim 7, wherein each turbulator
extends from the substrate with a second root portion of the at
least one root portion proximal to the substrate providing a
concave transition between the substrate and a second side of the
convex region of the turbulator.
9. The fabricated article of claim 8, wherein the first root
portion and the second root portion are raised from the substrate
to form at least a portion of the convex region extending from the
substrate.
10. The fabricated article of claim 9, wherein the convex region is
formed by a first fusion energy, the first concave portion is
formed by a second fusion energy, and the second concave portion is
formed by a third fusion energy.
11. The fabricated article of claim 1, wherein the substrate is
formed of a substrate material selected from the group consisting
of a composite material, a ceramic matrix composite, a superalloy,
a nickel-based alloy, an iron-based alloy, a cobalt-based alloy,
and any combination thereof.
12. The fabricated article of claim 1, wherein the one or more
turbulators are formed of a turbulator material selected from the
group consisting of ceramic matrix composite, a superalloy, a high
temperature metal, or a combination thereof.
13. The fabricated article of claim 1, wherein the concave
transition forms a smooth shape having a radius up to about 1.27
mm.
14. The fabricated article of claim 1, wherein the concave
transition forms a smooth shape having a radius up to about 0.76
mm.
15. A fabricated article comprising a substrate and one or more
turbulators on the substrate, the fabricated article being formed
by a turbulator fabrication process comprising: providing a system
configured for concurrently directing a first fusion energy and a
second fusion energy; positioning a turbulator material on the
substrate; and then concurrently directing the first fusion energy
toward a first side of the turbulator material extending from the
substrate and the second fusion energy toward a second side of the
turbulator material opposite the first side and extending from the
substrate; wherein the directing of the first fusion energy and the
second fusion energy shapes the first side of the turbulator
material to have a first contour and the second side of the
turbulator material to have a second contour, thereby forming the
one or more turbulators on the substrate.
16. A fabricated article comprising a substrate and one or more
turbulators on the substrate, the fabricated article being formed
by a turbulator fabrication process comprising: providing a system
configured for directing a first fusion energy and a second fusion
energy; positioning a turbulator material on the substrate; and
directing the first fusion energy and the second fusion energy
toward the turbulator material and the substrate; wherein the
directing of the first fusion energy and the second fusion energy
modifies the turbulator material forming the one or more
turbulators on the substrate; and wherein the turbulator extends
from the substrate with a first root portion proximal to the
substrate providing a concave transition between the substrate and
a first side of a convex region of the turbulator.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. Utility Application
No. 14/104,363, filed on Dec. 12, 2013, and entitled "A FABRICATION
PROCESS AND FABRICATED ARTICLE", the disclosure of which is hereby
incorporated by reference in its entirety.
FIELD OF THE INVENTION
[0002] The present invention is directed to a fabrication process
and a fabricated article. More specifically, the present invention
is directed to a turbulator fabrication process and a fabricated
article including turbulators.
BACKGROUND OF THE INVENTION
[0003] Many components, such as gas turbine combustors, are exposed
to increased temperatures during operation. For example, combustion
within a combustion chamber of a traditional gas turbine may
produce flame temperatures exceeding 3,900.degree. F. Often, the
components include tolerance temperatures well below the increased
temperatures experienced during operation. To maintain material
temperatures below the tolerance temperature, cooling features may
be incorporated into the component.
[0004] One cooling feature includes providing continuous linear
turbulators on an exterior surface of a component, such as a
combustor liner. The continuous linear turbulators include
protruding bodies placed in the flow path over the exterior surface
of the component to disrupt the flow. The disruption in the flow
creates shear layers and high turbulence to enhance heat transfer
on the exterior surface and increase convective cooling of the
component.
[0005] Often, a plurality of turbulators is formed on the exterior
surface of the component. Forming the plurality of turbulators may
require an extended period of time, which decreases efficiency and
increases both cost and fabrication time for the component. For
example, forming 90 turbulators by machining may take upwards of 24
hours for superalloys.
BRIEF DESCRIPTION OF THE INVENTION
[0006] In an exemplary embodiment, a fabricated article includes a
substrate and one or more turbulators formed on the substrate. Each
of the one or more turbulators includes at least one root portion
providing a concave transition between the substrate and the
turbulator.
[0007] In another exemplary embodiment, a fabricated article
includes a substrate and one or more turbulators on the substrate.
The fabricated article is formed by a turbulator fabrication
process including providing a system configured for concurrently
directing a first fusion energy and a second fusion energy. The
turbulator fabrication process also includes positioning a
turbulator material on the substrate and then concurrently
directing the first fusion energy toward a first side of the
turbulator material extending from the substrate and the second
fusion energy toward a second side of the turbulator material
opposite the first side and extending from the substrate. The
directing of the first fusion energy and the second fusion energy
shapes the first side of the turbulator material to have a first
contour and the second side of the turbulator material to have a
second contour, thereby forming the one or more turbulators on the
substrate.
[0008] In another exemplary embodiment, a fabricated article
includes a substrate and one or more turbulators on the substrate.
The fabricated article is formed by a turbulator fabrication
process including providing a system configured for directing a
first fusion energy and a second fusion energy. The turbulator
fabrication process also includes positioning a turbulator material
on the substrate and directing the first fusion energy and the
second fusion energy toward the turbulator material and the
substrate. The directing of the first fusion energy and the second
fusion energy modifies the turbulator material forming the one or
more turbulators on the substrate. The turbulator extends from the
substrate with a first root portion proximal to the substrate
providing a concave transition between the substrate and a first
side of a convex region of the turbulator.
[0009] Other features and advantages of the present invention will
be apparent from the following more detailed description of the
preferred embodiment, taken in conjunction with the accompanying
drawings which illustrate, by way of example, the principles of the
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 shows a flow chart of a fabrication process,
according to an embodiment of the disclosure.
[0011] FIG. 2 is a perspective view of a component having a
plurality of turbulators formed thereon, according to an embodiment
of the disclosure.
[0012] FIG. 3 is a process view of a process for forming a
turbulator, according to an embodiment of the disclosure.
[0013] FIG. 4 is a process view of a process for forming a
turbulator, according to an embodiment of the disclosure.
[0014] FIG. 5 is an enlarged cross-section view of a turbulator,
according to an embodiment of the disclosure.
[0015] Wherever possible, the same reference numbers will be used
throughout the drawings to represent the same parts.
DETAILED DESCRIPTION OF THE INVENTION
[0016] Provided are a fabrication process and a fabricated article.
Embodiments of the present disclosure, in comparison to fabrication
processes and fabricated articles not using one or more of the
features disclosed herein, increase turbulator fabrication
efficiency, increase turbulator formation speed, provide
turbulators including concave roots at increased fabrication
speeds, or a combination thereof
[0017] Referring to FIGS. 1-2, in one embodiment, a turbulator
fabrication process 100 includes providing a system 200 configured
for directing a first fusion energy 201 and a second fusion energy
202 (step 110), positioning a turbulator material 205 on a
substrate 207 (step 120), and directing the first fusion energy 201
and the second fusion energy 202 toward the turbulator material 205
and the substrate 207 (step 130). The directing of the first fusion
energy 201 and the second fusion energy 202 modifies the turbulator
material 205 to form one or more turbulators 210 on the substrate
207. As used herein, the term "turbulator" refers to a protruding
body configured to be placed in a flow path to transform laminar
flow into turbulent flow. The turbulent flow increases a cooling
effect of the fluid flowing over the substrate 207.
[0018] Referring to FIG. 2, the substrate 207 includes any suitable
substrate, such as, but not limited to, a portion of a combustion
liner, a convex surface, a concave surface, a planar surface, or a
combination thereof. Substrate materials include, but are not
limited to, composite materials, such as a ceramic matrix
composite, superalloys, a nickel-based alloy, an iron-based alloy,
a cobalt-based alloy, or a combination thereof.
[0019] Referring to FIG. 3, positioning the turbulator material 205
on the substrate 207 (step 120) includes providing the turbulator
material 205 to the substrate 207 in any suitable configuration for
forming a predetermined shape, orientation, and/or spacing of the
one or more turbulators 210. The turbulator material 205 positioned
on the substrate 207 includes a first interface 221 and a second
interface 222 between the turbulator material 205 and the substrate
207. The first interface 221 corresponds to a first side 231 of the
turbulator 210 formed from the turbulator material 205, and the
second interface 222 corresponds to a second side 232 of the
turbulator 210 formed from the turbulator material 205. One
suitable configuration for providing the turbulator material 205
includes a bead at least substantially devoid of concave surfaces.
Another suitable configuration includes providing the turbulator
material 205 around portions of the substrate 207, or entirely
around the substrate 207. For example, providing the bead at least
substantially devoid of concave surfaces extending around the
combustion liner. After positioning of the turbulator material 205,
the directing of the fusion energy (step 130) forms the one or more
turbulators 210 from the turbulator material 205. Suitable
turbulator material 205 includes, but is not limited to, a ceramic
matrix composite, a superalloy, a high temperature metal, or a
combination thereof.
[0020] The turbulator fabrication process 100 permits formation of
the one or more turbulators 210 on various substrate profiles.
During the turbulator fabrication process 100, the forming of the
one or more turbulators 210 from the turbulator material 205
includes a linear uninterrupted process, a linear interrupted
process, or a non-linear process. The type of process for forming
the one or more turbulators 210 is at least partially dependent
upon the configuration of the turbulator material 205 positioned on
the substrate 207. For example, in one embodiment, the one or more
turbulators 210 extend around the substrate 207, and are formed
with the linear uninterrupted process from the turbulator material
205 extending around the substrate 207. In another example, the one
or more turbulators 210 extend around portions of the substrate
207, and are formed with the linear interrupted process from the
turbulator material 205 extending around portions of the substrate
207. In yet another example, the one or more turbulators 210 extend
around portions of the substrate 207, and are formed with the
non-linear process from the turbulator material 205 extending
around portions of the substrate 207.
[0021] Referring to FIGS. 3-5, the first fusion energy 201 is
directed toward the turbulator material 205 and the substrate 207
to form a height 212 and/or a width 213 of the turbulator 210 (see
FIG. 5). The first fusion energy 201 is directed from a first
fusion energy source 241, such as, but not limited to, laser
energy, an arc beam, a plasma beam, or a combination thereof. The
height 212 of the turbulator 210 includes any suitable height for
disrupting laminar flow and/or introducing turbulence into a fluid
flow. Suitable heights include, but are not limited to, up to about
1.27 mm (0.05 inches), up to about 0.76 mm (0.03 inches), between
about 0.25 mm (0.01 inches) and about 1.02 mm (0.04 inches), or any
combination, sub-combination, range, or sub-range thereof In
another embodiment, the width 213 of the turbulator 210 includes
any suitable width for providing support to the turbulator 210.
Suitable widths include, but are not limited to, up to about 1.27
mm (0.05 inches), up to about 0.76 mm (0.03 inches), between about
0.25 mm (0.01 inches) and about 1.02 mm (0.04 inches), or any
combination, sub-combination, range, or sub-range thereof In a
further embodiment, the width 213 is similar, or substantially
similar, to the height 212. In an alternate embodiment, the width
213 differs from the height 212.
[0022] The second fusion energy 202 is directed toward the
turbulator material 205 and the substrate 207 to form a first root
portion 214 on a first side 231 and/or a second root portion 215 on
a second side 232 of the turbulator 210. The second fusion energy
202 is directed from a second fusion energy source 242, such as,
but not limited to, laser energy, an arc beam, a plasma beam, or a
combination thereof In one embodiment, the second fusion energy 202
is directed toward the first interface 221 to form the first root
portion 214 on the first side 231 of the turbulator 210. In another
embodiment, the second fusion energy 202 is split to direct the
second fusion energy 202 towards the first interface 221 and the
second interface 222. Directing the second fusion energy 202 toward
the first interface 221 and the second interface 222 forms the
first root portion 214 on the first side 231 and the second root
portion 215 on the second side 232, respectively.
[0023] In one embodiment, a third fusion energy 203 is directed
toward the turbulator material 205 and the substrate 207
concurrently with the first fusion energy 201 and the second fusion
energy 202. The third fusion energy 203 is directed from a third
fusion energy source 243, such as, but not limited to, laser
energy, an arc beam, a plasma beam, or a combination thereof. In an
embodiment with the third fusion energy 203, the first fusion
energy 201 is directed toward the turbulator material 205 and the
substrate 207, the second fusion energy 202 is directed towards the
first interface 221, and the third fusion energy 203 is directed
towards the second interface 222. The first fusion energy 201 forms
the height 212 and/or the width 213 of the turbulator 210, while
the second fusion energy 202 forms the first root portion 214 on
the first side 231 of the turbulator 210 and the third fusion
energy 203 forms the second root portion 215 on the second side 232
of the turbulator 210.
[0024] Referring to FIG. 5, together, the height 212 and the width
213 form a convex region of the turbulator 210 extending from the
substrate 207. The first root portion 214 and the second root
portion 215 form concave regions providing a transition between the
substrate 207 and the convex region of the turbulator 210. In one
embodiment, the first root portion 214 and/or the second root
portion 215 is raised from the substrate 207 to form at least a
portion of the convex region extending from the substrate 207. The
transition between the substrate 207 and the convex region of the
turbulator 210 includes an angle .alpha. of at least 90 degrees. In
one embodiment, the concave transition forms a smooth and/or
semi-circular shape having a radius including, but not limited to,
up to about 1.27 mm (0.05 inches), up to about 0.76 mm (0.03
inches), between about 0.25 mm (0.01 inches) and about 1.02 mm
(0.04 inches), or any combination, sub-combination, range, or
sub-range thereof. The concave transition is not limited to the
semi-circular shape, and may include any suitable shape not forming
an acute angle between the substrate 207 and the turbulator
210.
[0025] In an alternate embodiment, the first fusion energy 201 is
split at least once to direct the first fusion energy 201 toward
the turbulator material 205 and the substrate 207, the first
interface 221, and/or the second interface 222. In one example, the
first fusion energy 201 is split once to direct the first fusion
energy 201 toward the turbulator material 205 and the substrate
207, as well as the first interface 221. In another example, the
first fusion energy 201 is split into three beams to direct the
first fusion energy 201 toward the turbulator material 205 and the
substrate 207, the first interface 221, and the second interface
222.
[0026] Referring again to FIG. 3, during the directing (step 130),
the second fusion energy 202 and/or the third fusion energy 203
trail the first fusion energy 201 in a direction of formation 401.
The directing of the first fusion energy 201 proceeds in the
direction of formation 401 at any suitable rate for forming the
turbulator 210 including the first root portion 214 and/or the
second root portion 215. Suitable rates for directing the first
fusion energy 201 include, but are not limited to, up to about 35
inches per minute (ipm), between about 3 ipm and about 35 ipm,
between about 10 ipm and about 35 ipm, between about 20 ipm and
about 35 ipm, or any combination, sub-combination, range, or
sub-range thereof. The directing of the second fusion energy 202
and/or the third fusion energy 203 concurrently with the directing
of the first fusion energy 201 permits increased rates for forming
the turbulator 210 having the first root portion 214 and/or the
second root portion 215 including the angle .alpha.. Increased
rates include, but are not limited to, up to about 75 ipm, up to
about 50 ipm, between about 10 ipm and about 50 ipm, between about
15 ipm and about 45 ipm, between about 10 ipm and about 30 ipm,
between about 30 ipm and about 50 ipm, between about 20 ipm and
about 40 ipm, or any combination, sub-combination, range, or
sub-range thereof.
[0027] The first fusion energy 201, the second fusion energy 202,
and the third fusion energy 203 include any suitable power energy
source, such as, but not limited to, a 2 kW laser source. The first
fusion energy 201 is directed towards the turbulator material 205
and the substrate 207 with increased power as compared to the
second fusion energy 202 and/or the third fusion energy 203. For
example, in one embodiment, the first fusion energy 201 includes
any suitable power for forming the turbulator 210, such as, but not
limited to, between about 600 W and about 800 W, between about 650
W and about 750 W, between about 675 W and about 725 W, about 700
W, or any combination, sub-combination, range, or sub-range
thereof. In another embodiment, the second fusion energy 202 and/or
the third fusion energy 203 includes any suitable power for forming
the first root portion 214 and/or the second root portion, such as,
but not limited to, between about 200 W and about 400 W, between
about 250 W and about 350 W, between about 275 W and about 325 W,
about 300 W, or any combination, sub-combination, range, or
sub-range thereof
[0028] Referring to FIG. 4, in one embodiment, a powder feeding 250
is provided concurrently with the first fusion energy 201, the
second fusion energy 202, and/or the third fusion energy 203. The
powder feeding 250 deposits a powder material simultaneously with
the directing of the fusion energy (step 130). In one embodiment,
the powder feeding 250 provided concurrently with the first fusion
energy 201 deposits the powder material on the substrate 207 to
position the turbulator material 205 (step 120) simultaneously with
the directing of the fusion energy (step 130). In an alternate
embodiment, after positioning the turbulator material 205 on the
substrate 207 (step 120), the powder feeding 250 provided
concurrently with the first fusion energy 201 deposits the powder
material on the turbulator material 205 to increase the height 212
and/or the width 213 of the turbulator 210. The powder feeding 250
provided concurrently with the second fusion energy 202 and/or the
third fusion energy 203 deposits the powder material to fill an
acute angle formed by the first fusion energy 201, and/or form the
first root portion 214 or the second root portion 215.
[0029] The powder material includes, but is not limited to, the
turbulator material 205, any material including a similar or
substantially similar coefficient of thermal expansion (CTE) to the
turbulator material 205, a material to impart various predetermined
properties to the turbulator 210, or a combination thereof. In one
embodiment, the powder material provided concurrently with the
first fusion energy 201 differs from the powder material provided
concurrently with the second fusion energy 202 and/or the third
fusion energy 203. In an alternate embodiment, the powder material
provided concurrently with the first fusion energy 201 is similar,
or substantially similar, to the powder material provided
concurrently with the second fusion energy 202 and/or the third
fusion energy 203.
[0030] The powder feeding 250 includes a powder delivery rate
corresponding to the rate at which the directing (step 130)
proceeds in the direction of formation 401. Powder delivery rates
include, but are not limited to, between about 50 g/m and about 200
g/m, between about 50 g/m and about 150 g/m, up to about 100 g/m,
between about 50 g/m and about 100 g/m, about 99 g/m, or any
combination, sub-combination, range, or sub-range thereof.
[0031] In one embodiment, the substrate 207 and/or the turbulator
material 205 is pre-heated prior to the directing of at least the
first fusion energy 201. The pre-heating includes directing a
pre-heat energy toward the substrate 207 and/or the turbulator
material 205 to increase the temperature of the substrate 207
and/or the turbulator material 205. In another embodiment, the
turbulator 210 undergoes a post-heat treatment. The post-heat
treatment includes directing a post-heat energy toward the
turbulator 210 to either increase the temperature of the turbulator
210 or decrease a rate of cooling of the turbulator 210. The
pre-heat energy and the post-heat energy include any suitable
energy source, such as, but not limited to, laser energy, an arc
beam, a plasma beam, or a combination thereof.
EXAMPLE
[0032] In an example, a first laser energy with a power of 700 w is
directed towards an external surface of a combustion liner to form
a portion of the turbulator 210. The first laser energy is directed
from the first fusion energy source 241 concurrently with the
powder feeding 250 to deposit the powder material on the substrate
207 and position the turbulator material 205 (step 120)
simultaneously with the directing of the fusion energy (step 130).
Concurrently with the directing of the first laser energy, a second
laser energy with a power of 300 w is directed toward the first
side 231 of the turbulator 210, and a third laser energy with a
power of 300 w is directed toward the second side 232 of the
turbulator 210. The first laser energy, the second laser energy,
and the third laser energy proceed in the direction of formation
401 at 35 ipm, with the second laser energy and the third laser
energy trailing the first laser energy to form the first root
portion 214 and the second root portion 215, respectively.
Together, the first laser energy, the second laser energy, and the
third laser energy form 90 turbulators 210 in 2 hours or less with
the height 212 of each turbulator 210 being about 0.76 mm (about
0.03 inches), the width 213 of each turbulator 210 being about 0.76
mm (about 0.03 inches), and an angle .alpha. between each
turbulator 210 and the external surface being about 90 degrees.
Additionally, each of the turbulators 210 includes the first root
portion 214 on the first side 231 and the second root portion 215
on the second side 232, the first root portion 214 and the second
root portion 215 forming the concave interfaces including a radius
of about 0.76 mm (about 0.03 inches) between the turbulator 210 and
the external surface of the combustion liner.
[0033] While the invention has been described with reference to a
preferred embodiment, it will be understood by those skilled in the
art that various changes may be made and equivalents may be
substituted for elements thereof without departing from the scope
of the invention. In addition, many modifications may be made to
adapt a particular situation or material to the teachings of the
invention without departing from the essential scope thereof.
Therefore, it is intended that the invention not be limited to the
particular embodiment disclosed as the best mode contemplated for
carrying out this invention, but that the invention will include
all embodiments falling within the scope of the appended
claims.
* * * * *