U.S. patent application number 10/931680 was filed with the patent office on 2006-03-23 for curved extrusions and method of forming the same.
This patent application is currently assigned to The Boeing Company. Invention is credited to Tracy MacDonald-Schmidt, Kevin T. Slattery.
Application Number | 20060059848 10/931680 |
Document ID | / |
Family ID | 36072415 |
Filed Date | 2006-03-23 |
United States Patent
Application |
20060059848 |
Kind Code |
A1 |
MacDonald-Schmidt; Tracy ;
et al. |
March 23, 2006 |
Curved extrusions and method of forming the same
Abstract
A curved extrusion includes a body that has indefinite length
and a cross-section, and that is formed to contour and at least one
channel cut into the cross-section that is filled with deposited
material such that said cross-section of said body is restored. By
cutting the channels into the cross-section of the extrusion, the
extrusion may be easily formed onto a contoured tool to be curved
with lower forming and residual stresses and distortion. By filling
the channels with deposited material, the original cross-section
and strength of the extrusion can be restored. By adding a
transverse stiffener, the strength of the original extrusion may
not only be restored but also further improved. By depositing
material to create structural features the cross-section of the
extrusion may be locally changed. The method for forming curved
extrusions of the present invention may be used, for example, to
produce T-chords of an aircraft.
Inventors: |
MacDonald-Schmidt; Tracy;
(Redmond, WA) ; Slattery; Kevin T.; (St. Charles,
MO) |
Correspondence
Address: |
SHIMOKAJI & ASSOCIATES, P.C.
8911 RESEARCH DRIVE
IRVINE
CA
92618
US
|
Assignee: |
The Boeing Company
Chicago
IL
60606-1596
|
Family ID: |
36072415 |
Appl. No.: |
10/931680 |
Filed: |
August 31, 2004 |
Current U.S.
Class: |
52/716.1 |
Current CPC
Class: |
B21C 23/00 20130101;
B23K 26/34 20130101; B23K 26/32 20130101; B23K 2103/14 20180801;
B23P 15/00 20130101; B21C 23/002 20130101; B23K 35/0244 20130101;
B23K 35/325 20130101 |
Class at
Publication: |
052/716.1 |
International
Class: |
E04C 2/38 20060101
E04C002/38 |
Claims
1. A curved extrusion, comprising: a body made out of extrusion
material and having indefinite length and a cross-section, wherein
said body extends longitudinally and is formed to contour; and at
least one channel cut into said cross-section, wherein said channel
is filled with deposited material such that said cross-section of
said body is restored.
2. The curved extrusion of claim 1, wherein said body includes a
horizontal leg and a vertical leg.
3. The curved extrusion of claim 2, wherein said channel is cut
into said vertical leg.
4. The curved extrusion of claim 1, wherein said channel is filled
with a deposited vertical leg.
5. The curved extrusion of claim 3, wherein said deposited vertical
leg is created using laser powder forming deposition.
6. The curved extrusion of claim 1, wherein said channel is a
narrow channel.
7. The curved extrusion of claim 1, wherein said channel has a "V"
profile.
8. A curved extrusion, comprising: a body made out of extrusion
material and having indefinite length and a cross-section, wherein
said body extends longitudinally and is formed to contour; at least
one channel cut into said cross-section, wherein said channel is
filled with deposited material such that said cross-section of said
body is restored; and at least one structural feature deposited
onto said body, wherein said structural feature changes said
cross-section of said body locally.
9. The curved extrusion of claim 8, wherein said structural feature
is a transverse stiffener.
10. The curved extrusion of claim 8, wherein said structural
feature is deposited onto said body using filler/weld
techniques.
11. The curved extrusion of claim 8, wherein said body includes a
horizontal leg and a vertical leg, and wherein said structural
feature is deposited onto said horizontal leg supporting said
vertical leg.
12. The curved extrusion of claim 8, wherein said extrusion
material is a titanium alloy.
13. The curved extrusion of claim 8, wherein said extrusion
material is Ti-6Al-4V.
14. A curved extrusion, comprising: a body made out of extrusion
material and having indefinite length and a cross-section, wherein
said body extends longitudinally and is formed to contour; a first
channel cut into said cross-section, wherein said first channel is
filled with deposited material such that said cross-section of said
body is restored; a second channel cut into said cross-section,
wherein said second channel is filled with deposited material such
that said cross-section of said body is restored; and a transverse
stiffener, wherein said transverse stiffener is deposited in said
second channel such that said cross-section of said body is locally
changed.
15. The curved extrusion of claim 14, wherein said body includes a
horizontal leg and a vertical leg, wherein said first channel is
cut into said vertical leg, and wherein said first channel is a
narrow channel.
16. The curved extrusion of claim 14, wherein said body includes a
horizontal leg and a vertical leg, wherein said second channel is
cut into said vertical leg, and wherein said second channel has a
straight "V" profile.
17. The curved extrusion of claim 14, wherein said second channel
has a stepped "V" profile.
18. The curved extrusion of claim 14, wherein said second channel
has a profile that is a combination of a straight "V" and a stepped
"V".
19. The curved extrusion of claim 14, wherein said second channel
has a contoured profile.
20. The curved extrusion of claim 14, comprising at least one
additional first channel, wherein said at least one additional
first channel is cut into said cross-section.
21. The curved extrusion of claim 14, comprising at least one
additional second channel and at least one additional transverse
stiffener, wherein said at least one additional second channel is
cut into said cross-section, and wherein said at least one
additional transverse stiffener is deposited in said at least one
additional channel.
22. A curved extrusion, comprising: a titanium alloy body having
indefinite length and a cross-section including a horizontal leg
and an angled vertical leg, wherein said body extends
longitudinally and is formed to contour; at least one first channel
cut into said vertical leg, wherein said first channel is a narrow
channel, and wherein said first channel is filled with said
titanium alloy deposited such that said cross-section of said body
is restored; at least one second channel cut into said vertical
leg, wherein said second channel has a profile that is a
combination of a straight "V" and a stepped "V", and wherein said
second channel is filled with said titanium alloy deposited such
that said cross-section of said body is restored; at least one
transverse stiffener, wherein said transverse stiffener is
deposited in said second channel such that said cross-section of
said body is locally changed; and at least one structural feature
made out of said titanium alloy deposited onto said horizontal leg
supporting said vertical leg, wherein said structural feature
changes said cross-section of said body locally.
23. The curved extrusion of claim 22, wherein said titanium alloy
is deposited to fill said first channel, to fill said second
channel, to created said transverse stiffener, and to create said
structural feature using laser powder forming techniques.
24. The curved extrusion of claim 22, wherein said body is formed
to contour using a contoured tool.
25. The curved extrusion of claim 22, wherein said titanium alloy
is Ti-6AL-4V.
26. A T-chord of an aircraft, comprising: a body made out of
Ti-6AL-4V and having indefinite length and a cross-section
including a horizontal leg and an vertical leg, wherein said body
extends longitudinally and is formed to contour; at least one first
channel cut into said vertical leg, wherein said first channel is
filled with deposited Ti-6AL-4V such that said cross-section of
said body is restored; at least one second channel cut into said
vertical leg, wherein said second channel is filled with deposited
Ti-6AL-4V such that said cross-section of said body is restored;
and at least one transverse stiffener, wherein said transverse
stiffener is deposited in said second channel such that said
cross-section of said body is locally changed.
27. The T-chord of claim 26, wherein said transverse stiffener is
deposited onto said horizontal leg supporting said vertical
leg.
28. The T-chord of claim 26, wherein said Ti-6AL-4V is deposited
using laser powder forming techniques.
29. The T-chord of claim 26, wherein said first channel is a narrow
channel and wherein said second channel has straight "V"
profile.
30. A method for forming a curved extrusion, comprising the steps
of: cutting at least one channel into a straight extrusion having a
cross-section; clamping said extrusion to a contoured tool; filling
said channel by depositing material; restoring said cross-section;
and removing said extrusion from said contoured tool.
31. The method of claim 30, further comprising the step of:
retrieving a curved extrusion that is free of residual stress.
32. The method of claim 30, further comprising the steps of:
cutting at least one first channel being a narrow channel into said
cross-section; and cutting at least one second channel into said
cross-section having a "V" profile.
33. The method of claim 32, further comprising the step of:
depositing a transverse stiffener in said second channel before
filling said second channel.
34. The method of claim 30, further comprising the step of:
depositing material locally onto said extrusion to change said
cross-section.
35. The method of claim 30, further comprising the step of:
performing standard thermal treatments before removing said curved
extrusion from said contoured tool.
36. The method of claim 30, further comprising the step of: heating
said extrusion before clamping to contoured tool.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention generally relates to extrusions and,
more particularly, to curved extrusions that are free of residual
stress and to a method for forming a curved extrusion with reduced
forming and stresses.
[0002] The requirements for material used in the aerospace industry
are numerous. Demands include improved toughness, lower weight, as
well as increased resistance to fatigue and corrosion. The
boundaries of material properties are being constantly extended as
manufacturers strive to give the next generation of aircraft
improved performance while making them more efficient. Titanium and
its alloys are increasingly used in the aerospace industry because
of their excellent combination of high specific strength
(strength-to-weight ratio), which may be maintained at elevated
temperature, their fracture resistant characteristics, and their
exceptional resistance to corrosion. The titanium alloy currently
most commonly used is the alpha-beta alloy Ti6Al4V. This
conventional fine grain titanium alloy commonly used in section
sizes up to 200 mm and may be used up to approximately 750.degree.
F. Ti6Al4V is used to manufacture many aerospace airframe and
engine components, such as blades, discs, rings, fasteners, cases,
vessels, hubs, forgings, and T-chords. Despite the increased usage
and production of titanium and its alloys, they are expensive when
compared to many other metals and alloys, for example, aluminum and
its alloys, because of the complexity of the extraction process,
difficulty of melting, and problems during fabrication and
machining. Therefore, near net-shape methods, such as extrusions,
castings, isothermal forging, and powder metallurgy, have been
introduced to reduce the cost of manufacturing titanium
components.
[0003] The metal working process known as extrusion generally
involves pressing metal stock, such as an ingot or billet, through
a die opening matching the desired shape in order to form a product
having indefinite length and a substantially constant cross
section. Extrusion produces compressive and shear forces in the
stock. Since no tensile stress is produced, the high deformation is
possible without tearing the metal. The term extrusion is usually
applied to both the process and the product obtained. A near
net-shaped product may be obtained through extrusion, which is
especially desirable in costly and difficult to machine alloys,
such as alloys of titanium, steel, and nickel. Furthermore,
extrusions generally have low tooling costs. However, disadvantages
of extrusions include that extrusions have generally a constant
cross-section and that extrusions are straight (as shown in FIGS.
1a and 1b). FIG. 1a provides a cross-sectional view of a typical
prior art straight extrusion 10 shown in FIG. 1b. Extrusions may be
formed to contour as a finishing operation, but the forming process
may induce high residual stress in the extrusion and may result in
loose tolerances, which are both undesirable. High residual stress
of the extrusion may further result in distortion during machining.
Furthermore, it might be desirable for some applications to locally
change the cross-section of the extrusion.
[0004] For instance, one application of a titanium alloy extrusions
in the aerospace industry could be for T-chords of an aircraft.
T-chords may be used in assembling the wing to the fuselage of an
aircraft. T-chords could be manufactured very cost effectively as
extrusions since the T-chords are needed at long lengths having a
generally constant cross-section, and need to be able to carry
heavy loads. However, T-chords have to be curved to follow the
shape of an aircraft wing. Since the curving process would induce
residual stress within large extrusions, such as the T-chord,
distortion of the extrusion may become a problem for assembling the
T-chord. Presently, the problem is avoided either by cutting the
extrusion in smaller pieces to be assembled to the wing box or by
increasing the thickness of the cross-section of the
extrusions.
[0005] Other prior art methods to produce near net-shape titanium
and titanium alloy products include deposition processes, such as
Laser Additive Manufacturing.TM. (LAM) offered by AeroMet
Corporation (Eden Prairie, Minn.) and Laser Engineered Net
Shaping.TM. (LENS) developed by Sandia National Labs which is being
commercialized by Optomec Design Corporation. Both technologies
utilize laser powder forming where typically metal or ceramic
powder materials are delivered directly into a melt pool created by
a laser beam to form parts in layerwise fashion. The strength of
these technologies lies in the ability to fabricate fully dense
metal or metal alloy parts with good metallurgical properties at
reasonable speeds. While a variety of materials can be used such as
stainless steel, Inconel, copper, aluminum etc., reactive materials
such as titanium and titanium alloys are of particular interest.
LAM is a fabrication method, which can be used to manufacture
metallic preforms directly from computer-generated 3 D drawings. In
this manner, freestanding shapes may be generated without molds or
dies. The advantage of LENS lies in its ability to generate
components having overhanging structures that are fully dense.
However, these technologies have the disadvantage that the number
and size of the components formed is limited and that production of
components is costly. Deposition processes, such as LAM and LENS
are very much suitable, for example, to rapidly produce replacement
titanium components for the aerospace industries rather than to
produce components that are constantly needed in high numbers.
[0006] As can be seen, there is a need for extrusions that may be
formed to contour without inducing residual stress. Furthermore,
there is a need to make local changes to the cross-section of an
extrusion, for example, for the purpose of adding strength. Also,
there is a need to provide large contoured extrusions made out of
titanium or titanium alloys that are free of residual stress with
more design flexibility at lower costs, and with reduced lead
times. Moreover, there is a need to provide a method for forming
extrusions into curved shapes without inducing residual stress.
[0007] There has, therefore, arisen a need to provide curved
extrusions that are free of residual stress. There has further
arisen a need to provide large titanium and titanium alloy
extrusions that may be formed to contour. There has still further
arisen a need to provide a method for forming large extrusions
without inducing residual stress. There has still further arisen a
need to provide a method for local design changes of the
cross-section of extrusions.
SUMMARY OF THE INVENTION
[0008] The present invention provides curved extrusions that are
free of residual stress, extrusions that have local changes of the
cross-section, and a method for forming extrusions to contour
without inducing residual stress. The present invention further
provides large titanium and titanium alloy extrusions formed to
contour that are suitable for, but not limited to, applications in
the aerospace industry. The present invention still further
provides a method for forming extrusions without inducing residual
stress.
[0009] In one aspect of the present invention, a curved extrusion
comprises a body made out of material and having indefinite length
and a cross-section, and at least one channel cut into the
cross-section. The body extends longitudinally and is formed to
contour. The channel is filled with deposited material such that
the cross-section of the body is restored.
[0010] In another aspect of the present invention, a curved
extrusion comprises a body made out of material and having
indefinite length and a cross-section, at least one channel cut
into the cross-section, and at least one structural feature
deposited onto the body. The body extends longitudinally and is
formed to contour. The channel is filled with deposited material
such that the cross-section of the body is restored. The structural
feature changes the cross-section of the body locally.
[0011] In still another aspect of the present invention, a curved
extrusion comprises a body made out of material and having
indefinite length and a cross-section, a first channel cut into the
cross-section, a second channel cut into the cross-section, and a
transverse stiffener. The body extends longitudinally and is formed
to contour. The first channel is filled with deposited material
such that the cross-section of the body is restored. The transverse
stiffener is deposited in the second channel such that the
cross-section of the body is locally changed. The second channel is
filled with deposited material such that the cross-section of the
body is restored.
[0012] In a further aspect of the present invention, a curved
extrusion comprises a titanium alloy body having indefinite length
and a cross-section including a horizontal leg and an angled
vertical leg, at least one first channel cut into the vertical leg,
at least one second channel cut into the vertical leg, at least one
transverse stiffener, and at least one structural feature made out
of the titanium alloy deposited onto the horizontal leg supporting
the vertical leg. The body extends longitudinally and is formed to
contour. The first channel is a narrow channel. The first channel
is filled with titanium alloy deposited such that the cross-section
of the body is restored. The second channel has a profile that is a
combination of a straight "V" and a stepped "V". The transverse
stiffener is deposited in the second channel such that the
cross-section of the body is locally changed. The second channel is
filled with titanium alloy deposited such that the cross-section of
the body is restored. The structural feature changes the
cross-section of the body locally.
[0013] In still a further aspect of the present invention, a
T-chord of an aircraft comprises a body made out of Ti-6AL-4V and
having indefinite length and a cross-section including a horizontal
leg and an vertical leg, at least one first channel cut into the
vertical leg, at least one second channel cut into the vertical
leg, and a transverse stiffener. The body extends longitudinally
and is formed to contour. The first channel is filled with
deposited Ti-6AL-4V such that the cross-section of the body is
restored. The transverse stiffener is deposited in the second
channel such that the cross-section of the body is locally changed.
The second channel is filled with deposited Ti-6AL-4V such that the
cross-section of the body is restored.
[0014] In still another aspect of the present invention, a method
for forming a curved extrusion comprises the steps of: cutting at
least one channel into a straight extrusion having a cross-section;
clamping the extrusion to a contoured tool; filling the channel by
depositing material; restoring the cross-section; and removing the
extrusion from the contoured tool.
[0015] These and other features, aspects and advantages of the
present invention will become better understood with reference to
the following drawings, description and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1a is a cross-sectional view of a typical prior art
straight extrusion;
[0017] FIG. 1b is a side view of a typical prior art straight
extrusion;
[0018] FIG. 2 is a schematic view of a curved extrusion according
to one embodiment of the present invention;
[0019] FIG. 2a is a cross-sectional view of a curved extrusion
taken along line 2a-2a in accordance with an embodiment of the
present invention;
[0020] FIG. 2b is a cross-sectional view of a curved extrusion
taken along line 2b-2b in accordance with an embodiment of the
present invention;
[0021] FIG. 2c is a cross-sectional view of a curved extrusion
taken along line 2c-2c according to one embodiment of the present
invention;
[0022] FIG. 3 is a side view of an extrusion according to one
embodiment of the present invention;
[0023] FIG. 4 is a side view of an extrusion according to another
embodiment of the present invention;
[0024] FIG. 5 is a side view of an extrusion according to another
embodiment of the present invention;
[0025] FIG. 6 is a side view of an extrusion mounted onto a
contoured tool according to one embodiment of the present
invention;
[0026] FIG. 7 is a side view of a curved extrusion according to
another embodiment of the present invention;
[0027] FIG. 7a is a cross-sectional view of a curved extrusion
taken along line 7a-7a according to one embodiment of the present
invention;
[0028] FIG. 7b is a cross-sectional view of a curved extrusion
taken along line 7b-7b according to one embodiment of the present
invention; and
[0029] FIG. 8 is a flow chart of a method for forming large
extrusions without inducing residual stress according to another
embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0030] The following detailed description is of the best currently
contemplated modes of carrying out the invention. The description
is not to be taken in a limiting sense, but is made merely for the
purpose of illustrating the general principles of the invention,
since the scope of the invention is best defined by the appended
claims.
[0031] Broadly, an embodiment of the present invention provides a
curved extrusion that is free of residual stress. Contrary to the
known prior art, the extrusion as in one embodiment of the present
invention includes channels cut into one leg of the extrusion prior
to forming the extrusion to contour in order to prevent residual
stress. The curved extrusion as in one embodiment of the present
invention may be used, for example, in the aerospace industry. By
using the method for forming a curved extrusion as in one
embodiment of the present invention it will be possible to
manufacture large extrusions that are free of residual stress and
that may be formed to contour from materials such as titanium and
titanium alloys. This is not possible by using prior art methods.
Such curved titanium alloy extrusions could be used, for example,
to produce T-chords of an aircraft, which would result in lower
manufacturing costs and reduced lead times compared to prior art
methods.
[0032] In one embodiment, the present invention provides an
extrusion that includes at least one channel cut into one leg of
the extrusion, preferably the vertical leg. The number of channels
cut into the extrusion may depend on the length of the extrusion,
the contour that will be applied to the extrusion, and the purpose
of the extrusion. The profiles of the channels, such as narrow,
stepped "V", straight "V", and contoured may depend on the geometry
of the extrusion and the deposition method that will be used to
refill the channels. The purpose of the channels cut into the
extrusion as in one embodiment of the present invention, is to
reduce the forming stresses and out-of plane deflections within the
extrusion during the forming process. It is often difficult to form
typical straight prior art extrusions to contour using prior art
methods without using high forming stresses or having unintended
out-of plane distortion in the base or upstanding legs.
[0033] An embodiment of the present invention further provides a
curved extrusion, such as a titanium or titanium alloy extrusion,
that includes at least one channel that has been cut into the
vertical leg of the extrusion before the forming process and that
has been refilled using deposition methods after the forming
process. By refilling the cut channels, the original strength and
cross-section of the extrusion may be restored and a curved
extrusion free of residual stress as in one embodiment of the
current invention may be obtained. Contrary to prior art curved
extrusions, the curved extrusion as in one embodiment of the
present invention may be machined as needed without problems. The
forming to contour of a typical straight prior art extrusion may
induce high residual stress that may result in distortion during
machining of the finished part by, for example, drilling, sawing,
grinding, milling, reaming, or tapping. Furthermore, the deposition
process may be also used to add transverse stiffeners while
refilling the cut channels in order to improve the stability and
strength of the curved extrusion as in one embodiment. Contrary to
prior art extrusions that generally have a constant cross-section,
it may be possible to change the cross-section of the curved
extrusion as in one embodiment of the present invention by locally
adding structure, such as transverse stiffeners, by depositing
material.
[0034] An embodiment of the present invention further provides a
method for forming extrusions that may have changes in the
cross-section without inducing residual stress. By cutting channels
into an extrusion, forming the extrusion to a desired contour,
refilling the cut channels by depositing material into the
channels, and by adding design features, such as transverse
stiffeners to the cross-section of the extrusion as in one
embodiment of the present invention, a large curved titanium or
titanium alloy extrusion may be produced that is free of residual
stress and requires none or minimal machining before application in
the industry, for example, as a T-chord of an aircraft. It is not
possible to manufacture a curved extrusion free of residual stress
as in one embodiment of the present invention using prior art
methods for forming a generally straight extrusion to contour.
[0035] Referring now to FIG. 2, a schematic view of a curved
extrusion 20 is illustrated according to one embodiment of the
present invention. The curved extrusion 20 may include a body 25
made out of extrusion material and having indefinite length and a
cross-section 26 (FIG. 2c). Other cross-sections 26, for example,
K-shapes, T-shapes are possible. The body 25 may extend
longitudinally and may be formed to contour. The curved extrusion
20 may further include a channel 23 and a structural feature 24.
The channel 23 may be cut into the extrusion before forming the
extrusion to contour. The channel 23 may further be filled with
deposited material after forming the extrusion to contour. The
channel 23 may be filled such that the original cross-section 26 is
restored. The structural feature 24, such as a transverse stiffener
may be deposited using prior art metal powder forming or other
deposition processes. The structural feature 24 may be deposited
such that the cross-section 26 is locally changed. The curved
extrusion 20 (as shown in FIG. 2) may have the desired final shape
of a part being manufactured. The extrusion 20 may be made out of
any material that may be extruded. A desired material for the
extrusion 20 may be titanium and titanium alloys, for example the
titanium alloy Ti-6Al-4V, since these materials are increasingly
used in the aerospace industry and other industries. Metal powder
forming processes, such as LAM, LENS, and others, may be used to
fill the channel 23 or to create the structural feature 24 by
depositing material similar to the extrusion material. LAM and LENS
may be especially suitable for depositing titanium and titanium
alloys. The deposition of the material may further be done using
other filler/weld techniques.
[0036] Referring now to FIG. 2c, a cross-sectional view of the
curved extrusion 20 taken along line 2c-2c is illustrated according
to one embodiment of the present invention. The cross-section taken
along line 2c-2c may be the original cross-section 26 of the
extrusion 20 before forming. The extrusion 20 includes a horizontal
leg 21 and a vertical leg 22. The vertical leg 22 is shown as
angled. The vertical leg 22 may also be straight. The extrusion 20
may further include more than one vertical leg 22 and/or more than
one horizontal leg 21.
[0037] Referring now to FIG. 2a, a cross-sectional view of the
curved extrusion 20 taken along line 2a-2a is illustrated according
to one embodiment of the present invention. FIG. 2a shows the
vertical leg 221 that has been deposited to refill the cut channel
23. As can be seen, the channel 23 may be filled with the deposited
vertical leg 221 such that the original cross-section 26 of the
extrusion 20, as shown in FIG. 2c, is restored.
[0038] Referring now to FIG. 2b, a cross-sectional view of the
curved extrusion 20 taken along line 2b-2b is illustrated according
to one embodiment of the present invention. FIG. 2b shows the
structural feature 24 as a transverse stiffener deposited to
support the vertical leg 22. The structural feature 24 may be
deposited onto the horizontal leg 21 supporting the vertical leg
22. By adding the structural feature 24, for example, the strength
of the extrusion 20 may be improved. Furthermore, the structural
feature 24 may be a added according to the desired final shape of
the part being manufactured changing the cross-section 26 (FIG. 2c)
locally.
[0039] Referring now to FIG. 3, a side view of an extrusion 30 is
illustrated according to one embodiment of the present invention.
The extrusion 30 may include a horizontal leg 31 and a vertical leg
32. The extrusion 30 may have a body 25 that may have, but is not
limited to, the same cross-section 26 as the extrusion 20 shown in
FIG. 2c. The extrusion 30 may be a generally straight extrusion
having indefinite length and extending longitudinally. The
extrusion 30 may be created by pressing metal stock, such as an
ingot or billet, through a die opening matching the desired shape
(prior art). The extrusion 30 may further include a channel 33 and
a channel 34 cut into the vertical leg 32. The channel 33 may have,
but is not limited to, a narrow profile (as shown in FIGS. 3, 4, 5,
6, and 7). The channel 34 may have, but is nor limited to, a
stepped "V" profile (as shown in FIG. 3), a straight "V" profile
(as shown in FIG. 4), a contoured profile (as shown in FIG. 5), or
a combination of profiles, such as a combination of a stepped and a
straight "V" (as shown in FIGS. 6 and 7). The profile of the
channels 33 and 34 may be selected according to the desired final
shape of the part being manufactured and by the deposition process
to fill the channel 33 and the channel 34. Furthermore, it may be
necessary to cut either channel 33 or channel 34 into the extrusion
30 instead of cutting both, and it may further be necessary to cut
more than the two channels 33 and 34 depending on the contour the
extrusion has to be formed to.
[0040] Referring now to FIG. 6, a side view of an extrusion 30
mounted onto a contoured tool 40 is illustrated according to one
embodiment of the present invention. The extrusion 30 may include a
body 25 that may have, but is not limited to, the same
cross-section 26 as the extrusion 20 shown in FIG. 2c. The
extrusion 30 may be a generally straight extrusion having
indefinite length and extending longitudinally. The extrusion 30
may further include a horizontal leg 31, a vertical leg 32, a first
channel 33, and a second channel 34. The extrusion 30 may have the
same cross-section as the extrusion 20 shown in FIG. 2c. The
channel 33 may have a narrow profile. The channel 34 may have a
combination of a stepped and a straight "V" profile. The extrusion
30 may be formed to or clamped to a contoured tool 40. The
contoured tool 40 may have the same contour as the part being
manufactured (curved extrusion 20 as shown in FIG. 2). The channels
33 and 34 may make the forming of the extrusion 30 to the contoured
tool 40 easier. The number and the profile of channels, for
example, channel 33 and 34 may be selected such that no residual
stress will be induced within the extrusion 30 during forming or
clamping to the contoured tool 40. Residual stresses are those
stresses which remain in a component, such as the extrusion 30,
following manufacture, processing, fabrication or assembly, such as
forming or clamping to the contoured tool 40. It is unlikely that
any component will be entirely free from residual stresses induced
during manufacturing and processing. By stating that no residual
stress is induced it is meant that the level of residual stress
induced is not significant and, therefore, will not have an effect
on further machining and application of the extrusion 30. The
forming of the extrusion 30 to the contoured tool 40 may be
performed hot or cold and may involve plastic deformation and/or
elastic deformation of the extrusion 30. By forming the extrusion
30 to the contoured tool 40, the profile of the channel 33 and the
channel 34 may change depending on the contour of tool 40. For
example, channel 33 may now have a slight "V" shape and the "V"
profile of channel 34 may widen. After forming the extrusion 30 to
the contoured tool 40, the extrusion 30 may be stress relieved or
annealed at an elevated temperature. For example, the titanium
alloy Ti-6Al-4V may be stress relieved or annealed at a temperature
between greater than 1550.degree. F. for a time greater than 2
hours.
[0041] Referring now to FIG. 7, a side view of a curved extrusion
50 is illustrated according to another embodiment of the present
invention. The extrusion 50 may have a body 25 that may have, but
is not limited to, the same cross-section 26 as the extrusion 20
shown in FIG. 2c. The extrusion 50 may be a generally straight
extrusion having indefinite length and extending longitudinally.
The curved extrusion 50 may include a horizontal leg 31, a vertical
leg 32, a deposited vertical leg 51, and a transverse stiffener 52.
The extrusion 50 may have the same cross-section 26 as the
extrusion 20 shown in FIG. 2c. The curved extrusion 50 may be
mounted to a contoured tool 40. The deposited vertical leg 41 may
be created by depositing material in the location of channel 33 (as
shown in FIGS. 3, 4, 5, and 6). By creating the deposited leg 51,
the original cross-section 26 of the extrusion 50 (as shown in FIG.
2c) may be restored, as can be seen in FIG. 7a. FIG. 7a illustrates
the cross-section of the extrusion 50 taken along line 7a-7a. The
transverse stiffener 52 may be created by depositing material in
the location of channel 34 (as shown in FIGS. 3, 4, 5, and 6). FIG.
7b illustrates the cross-section of the extrusion 50 taken along
line 7b-7b showing the transverse stiffener 52 changing the
original cross-section 26 (shown in FIG. 2c). Since the transverse
stiffener 52 may not fill the channel 34 completely, additional
material 53 may need to be deposited in order to refill the channel
34 completely (FIG. 7). The additional material 53 may be deposited
such that the cross-section 26 is restored. The deposition of the
material to fill the channel 33, channel 34, and to create the
transverse stiffener 52 may be done using laser powder forming
techniques, such as LAM and LENS. The deposition of the material
may further be done using other filler/weld techniques. The
deposition method may be selected depending on the cross-section of
the extrusion 50 and the size of the cut channels, for example
channels 33 and 34 (shown in FIGS. 3, 4, 5, and 6). By adding
material 53 back to the cut channels, such as channels 33 and 34,
the strength of the original extrusion 30 (shown in FIGS. 3, 4, 5,
and 6), may be restored. By adding the transverse stiffener 52, the
strength of the original extrusion 30 (shown in FIGS. 3, 4, 5, and
6), may not only be restored but further improved. After the
deposition of the material, the extrusion 50 may remain clamped to
the contoured tool 40 and undergo standard stress relief,
annealing, and aging procedures typical for the extrusion material
used. For example, the titanium alloy Ti-6Al-4V may be thermally
treated at a temperature greater than 1550.degree. F. for a time
greater than 2 hours. Titanium and titanium alloys, for example,
titanium alloy Ti-6Al-4V, are materials that may be highly suitable
to manufacture a curved extrusion 50, as shown in FIG. 7.
[0042] Referring now to FIG. 8, a flow chart of a method 60 for
forming a curved extrusion 20 or 50 without inducing residual
stress is illustrated according to another embodiment of the
present invention. The method 60 for forming a curved extrusion 20
or 50 may include the steps of: creating a straight extrusion 30 by
pressing metal stock, such as an ingot or billet, through a die
opening matching the desired shape in order to form a product
having indefinite length and a substantially constant cross section
(step 61--prior art); cutting channels 33 and 34 into the vertical
leg 32 of the extrusion 30 (step 62); clamping the extrusion 30 to
a contoured tool 40 (step 63); depositing a transverse stiffener 52
into channel 34 as needed (step 64); filling the channels 33 and 34
by depositing material 53 in the channels 33 and 34 using laser
powder forming techniques (step 65); locally depositing material to
change the cross-section of the extrusion according to the desired
final shape of the part being manufactured (step 66); performing
standard thermal treatments, such as stress relief, annealing, and
aging procedures, while the extrusion 50 is still clamped to the
contoured tool 40 (step 67); removing extrusion 50 from the
contoured tool 40 (step 68); and retrieving a curved extrusion 20
or 50 that is free of residual stress (step 69). The curved
extrusion 20 or 50 may be free of residual stress, which means the
curved extrusion 20 or 50 may have a residual stress level that is
not significant regarding further machining or application of the
extrusion 20 or 50. The extrusion 30 may be heated before clamping
to contoured tool 40. By cutting the channels 33 and 34 into the
vertical leg 32 of the extrusion 30, the extrusion 30 may be easily
formed onto the contoured tool 40 with reduced forming and residual
stresses. By filling the channels 33 and 34 with deposited material
53, the original cross-section 26 and strength of the extrusion 30
may be restored. By adding the transverse stiffener 52, the
strength of the original extrusion 30 may not only be restored but
further improved. The method 60 for forming a curved extrusion may
be used to manufacture large curved extrusion (long length) having
local changes in the cross-section. Such parts may be needed, for
example, in the aerospace industry. For example, T-chords of
aircraft could be manufactured using method 60. Furthermore, the
method 60 may be suitable to manufacture titanium and titanium
alloy parts as needed in the aerospace industry with low costs and
reduced lead times by lowering non-recurring tooling costs and
recurring set-up time and costs compared to prior art manufacturing
methods. Although the curved extrusions 20 and 50 and the method 60
for forming a curved extrusion 20 or 50 without inducing residual
stress have been described for the cross-section illustrated in
FIG. 2c and for titanium and titanium alloys, other cross-sections
as well as other extrusion materials may be used.
[0043] It should be understood, of course, that the foregoing
relates to exemplary embodiments of the invention and that
modifications may be made without departing from the spirit and
scope of the invention as set forth in the following claims.
* * * * *