U.S. patent application number 12/614205 was filed with the patent office on 2010-05-13 for large diameter thermoplastic seal.
This patent application is currently assigned to SAINT-GOBAIN PERFORMANCE PLASTICS CORPORATION. Invention is credited to Ceyhan Celik, Sarah L. Clark, Hamid Reza Ghalambor, Gary Charles Hildreth, Helina Joshi, Jose Sousa, Karthik Vaideeswaran, Christophe Valdenaire.
Application Number | 20100117310 12/614205 |
Document ID | / |
Family ID | 42153594 |
Filed Date | 2010-05-13 |
United States Patent
Application |
20100117310 |
Kind Code |
A1 |
Celik; Ceyhan ; et
al. |
May 13, 2010 |
LARGE DIAMETER THERMOPLASTIC SEAL
Abstract
A seal ring includes a weld and a thermoplastic material. The
thermoplastic material has a weld elongation-at-break of at least
3%. The thermoplastic material can have a glass transition
temperature of at least 100.degree. C. The thermoplastic material
with the weld can have a weld elongation-at-break of at least 3%.
The seal ring can have a circumference of at least 0.62 meters. The
seal ring can have a coefficient of friction of not greater than
0.45.
Inventors: |
Celik; Ceyhan; (Dracut,
MA) ; Clark; Sarah L.; (Somerville, MA) ;
Hildreth; Gary Charles; (North Oxford, MA) ; Joshi;
Helina; (Shrewsbury, MA) ; Vaideeswaran; Karthik;
(Redondo Beach, CA) ; Valdenaire; Christophe;
(Clapiers, FR) ; Sousa; Jose; (East Providence,
RI) ; Ghalambor; Hamid Reza; (Irvine, CA) |
Correspondence
Address: |
LARSON NEWMAN & ABEL, LLP
5914 WEST COURTYARD DRIVE, SUITE 200
AUSTIN
TX
78730
US
|
Assignee: |
SAINT-GOBAIN PERFORMANCE PLASTICS
CORPORATION
Aurora
OH
|
Family ID: |
42153594 |
Appl. No.: |
12/614205 |
Filed: |
November 6, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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61112427 |
Nov 7, 2008 |
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61112421 |
Nov 7, 2008 |
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61116901 |
Nov 21, 2008 |
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61166543 |
Apr 3, 2009 |
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Current U.S.
Class: |
277/650 ;
277/628 |
Current CPC
Class: |
F16J 15/108 20130101;
F16J 15/00 20130101; B29C 65/00 20130101; F16J 15/102 20130101;
C09K 2200/0657 20130101; F16J 15/022 20130101; F16J 15/06 20130101;
C09K 3/10 20130101; Y10T 428/215 20150115 |
Class at
Publication: |
277/650 ;
277/628 |
International
Class: |
F16J 15/10 20060101
F16J015/10 |
Claims
1. A seal ring comprising a weld and comprising a thermoplastic
material having a weld elongation-at-break of at least 3%.
2. The seal ring of claim 1, wherein the seal ring has a
circumference of at least 0.62 meters.
3. (canceled)
4. The seal ring of claim 1, wherein the seal ring has a diameter
of at least 0.2 meters.
5. The seal ring of claim 4, wherein the diameter is at least 1.3
meters.
6. (canceled)
7. The seal ring of claim 1, wherein the thermoplastic material is
selected from the group consisting of a polyketone, a polyaramid, a
polyimide, a polyetherimide, a polyamideimide, a polyphenylene
sulfide, a polyphenylene sulfone, a fluoropolymer, a
polybenzimidazole, a liquid crystal polymer, a derivation thereof,
or a combination thereof.
8. (canceled)
9. The seal ring of claim 7, wherein the thermoplastic material is
a polyketone material selected from the group consisting of
polyether ether ketone, polyether ketone, poly ether ketone ketone,
a derivation thereof, and a combination thereof.
10. (canceled)
11. The seal ring of claim 1, wherein the thermoplastic material
comprises ultra high molecular weight polyethylene.
12. The seal ring of claim 1, wherein the seal ring has a
coefficient of friction of not greater than 0.45.
13.-14. (canceled)
15. The seal ring of claim 1, wherein the thermoplastic material
has a melting point of at least 250.degree. C.
16.-17. (canceled)
18. The seal ring of claim 1, wherein the thermoplastic material
has a glass transition temperature of at least 100.degree. C.
19.-20. (canceled)
21. The seal ring of claim 1, wherein the thermoplastic material
has a tensile strength of at least 3100 psi.
22.-23. (canceled)
24. The seal ring of claim 1, wherein the tensile modulus is at
least 100 ksi.
25.-26. (canceled)
27. The seal ring of claim 1, wherein the weld elongation-at-break
is at least 5%.
28. The seal ring of claim 27, wherein the weld elongation-at-break
is at least 10%.
29.-36. (canceled)
37. A seal ring having a weld and comprising a thermoplastic
material having a glass transition temperature of at least
100.degree. C., the thermoplastic material with the weld having a
weld elongation-at-break of at least 3%, the seal ring having a
circumference of at least 0.62 meters, the seal ring having a
coefficient of friction of not greater than 0.45.
38.-39. (canceled)
40. The seal ring of claim 37, wherein the weld elongation-at-break
is at least 5%.
41.-47. (canceled)
48. A seal ring comprising extruded PEEK material having a weld
elongation-at-break of at least 3%, the seal ring having a
circumference of at least 1.5 meters.
49. The seal ring of claim 48, wherein the extruded PEEK material
is a composite material comprising a filler.
50.-53. (canceled)
54. The seal ring of claim 48, wherein the weld elongation-at-break
is at least 5%.
55.-57. (canceled)
58. The seal ring of claim 48, further comprising a weld.
59. (canceled)
Description
CROSS REFERENCE TO RELATED APPLICATION(S)
[0001] The present application claims priority from U.S.
Provisional Patent Application No. 61/112,427, filed Nov. 7, 2008,
entitled "METHOD OF FORMING LARGE DIAMETER THERMOPLASTIC SEAL,"
naming inventors Ceyhan Celik, Sarah L. Clark, Gary Charles
Hildreth, Jr., Helina Joshi, Karthik Vaideeswaran, and Christophe
Valdenaire, U.S. Provisional Patent Application No. 61/112,421,
filed Nov. 7, 2008, entitled "METHOD OF FORMING LARGE DIAMETER
THERMOPLASTIC SEAL," naming inventors Sarah L. Clark, Ceyhan Celik,
Gary Charles Hildreth, Jr., and Helina Joshi, U.S. Provisional
Patent Application No. 61/116,901, filed Nov. 21, 2008, entitled
"METHOD OF FORMING LARGE DIAMETER THERMOPLASTIC SEAL," naming
inventors Sarah L. Clark, Ceyhan Celik, Gary Charles Hildreth, Jr.,
and Helina Joshi, and U.S. Provisional Patent Application No.
61/166,543, filed Apr. 3, 2009, entitled "METHOD OF FORMING LARGE
DIAMETER THERMOPLASTIC SEAL," naming inventors Karthik
Vaideeswaran, Jose R. Sousa, Hamid Reza Ghalambor, and Sarah L.
Clark, which applications are incorporated by reference herein in
their entirety.
FIELD OF THE DISCLOSURE
[0002] This disclosure, in general, relates to thermoplastic seals,
and in particular to large diameter thermoplastic seals.
BACKGROUND
[0003] Various industries are increasingly turning to large-scale
equipment to meet operational demands. As industry develops
large-scale equipment, it seeks large-scale components, such as
seals and o-rings. Often, the large-scale equipment is located in
remote harsh environments, increasing demand for durable and hardy
seals. For example, as the oil and gas industry seeks to drill in
deeper water, the scale of the equipment used is increasing and, as
a result, the demand for more durable, large-scale products that
can survive harsh environments increases. However, conventional
methods for forming thermoplastic seals do not produce large
diameter seals having desirable mechanical properties.
[0004] One conventional method includes compression molding.
Conventional compression molded seals have poor mechanical
properties, such as low elongation-at-break. As a result, seals
formed through such conventional compression molding techniques
tend to have a low durability and poor performance.
[0005] Other conventional techniques limit the size of the seals
that can be made and tend to produce a significant amount of waste.
For example, circular seals may be cut from an extruded sheet of
thermoplastic material, leaving a significant amount of waste
material. In addition, the size of the seals is limited by the
width of the sheet of thermoplastic material.
[0006] As such, a new method of forming a seal would be
desirable.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] The present disclosure may be better understood, and its
numerous features and advantages made apparent to those skilled in
the art by referencing the accompanying drawings.
[0008] FIG. 1 and FIG. 2 include illustrations of exemplary
seals.
[0009] FIG. 3 and FIG. 4 include block diagrams of exemplary
methods for forming seals.
[0010] FIG. 5 includes an illustration of a forming device.
[0011] FIG. 6 includes an illustration of an exemplary heater.
[0012] FIG. 7 includes an illustration of an exemplary stencil for
cutting.
[0013] FIG. 8 includes an illustration of an exemplary
thermoplastic rod.
[0014] FIG. 9 includes an illustration of an exemplary extruded
material.
[0015] FIG. 10 includes an illustration of an exemplary welding
device.
[0016] The use of the same reference symbols in different drawings
indicates similar or identical items.
DESCRIPTION OF THE DRAWINGS
[0017] In a particular embodiment, a method for forming a seal ring
includes heating an extruded rod, bending the extruded rod, joining
the ends of the extruded rod to form a semi-finished ring, and
annealing the semi-finished ring. The semi-finished ring may be
machined or further processed to form a seal ring, back-up ring, or
other seal device, collectively referred to as seal rings herein.
In an example, joining the ends of the extruded rod includes
welding the ends of the extruded rod by melting the ends and
pressing the ends together. In particular, heating the extruded
rods includes heating the rods to a temperature greater than the
glass transition temperature. For example, the extruded rods may be
heated to a heat index in a range of 0.65 to 0.999. In a further
example, the semi-finished ring is annealed at a temperature
greater than a glass transition temperature for a period of at
least two hours.
[0018] In another exemplary embodiment, a seal ring includes an
extruded thermoplastic material having a weld elongation-at-break
of at least 5% as per ASTM D638 testing specification. The seal
ring has a circumference of at least 1.5 meters. For example, the
seal ring may have a diameter of at least 1.3 meters. In an
example, the seal ring includes at least one weld. In a particular
example, the extruded thermoplastic material includes a
thermoplastic material having a glass transition temperature
greater than 100.degree. C. In a further example, the extruded
thermoplastic material has a coefficient of friction of not greater
than 0.45. In addition, the thermoplastic material may have a
tensile strength at yield of at least 3100 psi (21.4 MPa).
[0019] As illustrated in FIG. 1, a seal ring 100 may include a
thermoplastic rod 102. In an example, the thermoplastic rod is an
extruded thermoplastic rod, such as a melt extruded rod. In
particular, the extruded thermoplastic rod is not paste extruded.
Alternatively, the rod 102 may be a compression molded rod. The
ends of the thermoplastic rod 102 may be joined at a weld 104. In
another embodiment illustrated in FIG. 2, a seal ring 200 may
include thermoplastic rods 202 and 204. The thermoplastic rods 202
and 204 may be joined at their ends at welds 206 and 208. While the
methods described herein are generally described in relation to
seal rings formed from a single bent rod, the methods can be
extended to seal rings formed from more than one thermoplastic rod,
for example, 2, 3, 4, or more extruded rods.
[0020] FIG. 3 includes an illustration of an exemplary method 300
for forming a seal ring. The method includes heating an extruded
thermoplastic rod, as illustrated at 302. Alternatively, the rod
may be a compression molded rod. The thermoplastic rod may be
formed of a thermoplastic material, such as an engineering or high
performance thermoplastic polymer. For example, the thermoplastic
material may include a polymer, such as a polyketone, polyaramid, a
thermoplastic polyimide, a polyetherimide, a polyphenylene sulfide,
a polyethersulfone, a polysulfone, a polyphenylene sulfone, a
polyamideimide, ultra high molecular weight polyethylene, a
thermoplastic fluoropolymer, a polyamide, a polybenzimidazole, a
liquid crystal polymer, or any combination thereof. In an example,
the thermoplastic material includes a polyketone, a polyaramid, a
polyimide, a polyetherimide, a polyamideimide, a polyphenylene
sulfide, a polyphenylene sulfone, a fluoropolymer, a
polybenzimidazole, a derivation thereof, or a combination thereof.
In a particular example, the thermoplastic material includes a
polymer, such as a polyketone, a thermoplastic polyimide, a
polyetherimide, a polyphenylene sulfide, a polyether sulfone, a
polysulfone, a polyamideimide, a derivative thereof, or a
combination thereof. In a further example, the thermoplastic
material includes polyketone, such as polyether ether ketone
(PEEK), polyether ketone, polyether ketone ketone, polyether ketone
ether ketone ketone, a derivative thereof, or a combination
thereof. An example thermoplastic fluoropolymer includes
fluorinated ethylene propylene (FEP), polytetrafluoroethylene
(PTFE), polyvinylidene fluoride (PVDF), perfluoroalkoxy (PFA), a
terpolymer of tetrafluoroethylene, hexafluoropropylene, and
vinylidene fluoride (THV), polychlorotrifluoroethylene (PCTFE),
ethylene tetrafluoroethylene copolymer (ETFE), ethylene
chlorotrifluoroethylene copolymer (ECTFE), or any combination
thereof. An exemplary liquid crystal polymer includes aromatic
polyester polymers, such as those available under tradenames
XYDAR.RTM. (Amoco), VECTRA.RTM. (Hoechst Celanese), SUMIKOSUPER.TM.
or EKONOL.TM. (Sumitomo Chemical), DuPont HX.TM. or DuPont
ZENITE.TM. (E.I. DuPont de Nemours), RODRUN.TM. (Unitika),
GRANLAR.TM. (Grandmont), or any combination thereof. In an
additional example, the thermoplastic polymer may be ultra high
molecular weight polyethylene. Ultra high molecular weight
polyethylene may be used in this process even though its glass
transition temperature is approximately -160.degree. C.
[0021] The thermoplastic material may also include a filler, such
as a solid lubricant, a ceramic or mineral filler, a polymer
filler, a fiber filler, a metal particulate filler or salts or any
combination thereof. An exemplary solid lubricant includes
polytetrafluoroethylene, molybdenum disulfide, tungsten disulfide,
graphite, graphene, expanded graphite, boron nitride, talc, calcium
fluoride, cerium fluoride, or any combination thereof. An exemplary
ceramic or mineral includes alumina, silica, titanium dioxide,
calcium fluoride, boron nitride, mica, Wollastonite, silicon
carbide, silicon nitride, zirconia, carbon black, pigments, or any
combination thereof. An exemplary polymer filler includes
polyimide, liquid crystal polymers such as Ekonol.RTM. polyester,
polybenzimidazole, polytetrafluoroethylene, any of the
thermoplastic polymers listed above, or any combination thereof. An
exemplary fiber includes nylon fibers, glass fibers, carbon fibers,
polyacrylonitrile fibers, polyaramid fibers,
polytetrafluoroethylene fibers, basalt fibers, graphite fibers,
ceramic fibers, or any combination thereof. Exemplary metals
include bronze, copper, stainless steel, or any combination
thereof. An exemplary salt includes a sulfate, a sulfide, a
phosphate, or any combination thereof.
[0022] In an exemplary embodiment, the rod may be formed of an
extruded composite material. For example, the composite material
may be formed of a thermoplastic material matrix and a filler. In a
particular example, the filler is a solid lubricant. In another
example, the filler includes a fluoropolymer. In a further example,
the filler includes a combination of solid lubricant and
fluoropolymer. In an embodiment, the composite material includes a
polyketone matrix, such as PEEK, and includes a solid lubricant
filler. In another exemplary embodiment, the composite material
includes a polyketone matrix, such as PEEK, and includes a carbon
filler which may be selected from graphite, carbon black, carbon
fiber or any combination thereof.
[0023] In a further embodiment, the rod may be partially formed of
a composite and partially formed of an unfilled material. As
illustrated in FIG. 8, a rod 900 may include a center portion 902
formed of a composite material and may include end portions 904 and
906 formed of unfilled polymer. For example, the center portion 902
may be a filled polymer, such as a PTFE filled PEEK material, and
the end portions 904 and 906 may be formed of a unfilled polymer,
such as neat PEEK. In a particular embodiment, a rod, such as the
rod 900 of FIG. 8, may be formed from an extruded material having a
composition that changes along a longitudinal axis. For example,
FIG. 9 includes an illustration of an extruded material 1000 that
includes composite portions 1002 and unfilled portions 1004. In an
example, the extruded material 1000 may be cut at the unfilled
portions 1004 to form a rod, such as the rod 900 of FIG. 8. In a
particular example, the extruded material 1000 may be formed by
extruding two materials through a single die and varying the rate
of extrusion of the two materials in an opposite manner.
[0024] In an example, heating the extruded rod includes heating the
extruded rod to a temperature greater than the glass transition
temperature of the thermoplastic material of the rod. In
particular, the thermoplastic rod may be heated to a temperature
greater than the glass transition temperature, but less than the
melting point of the thermoplastic material. For example, the
extruded thermoplastic rod may be heated to a heat index in a range
of 0.60 to 0.999. The heat index is a ratio of the temperature to
which a material is heated divided by the melting point. In a
further example, the heat index may be in a range of 0.70 to 0.999,
such as a range of 0.8 to 0.999, or even a range of 0.9 to
0.99.
[0025] In an example, the thermoplastic material has a melting
point of at least 250.degree. C. For example, the thermoplastic
material may have a melting point of at least 300.degree. C., such
as at least 320.degree. C. Further, the thermoplastic material may
have a glass transition temperature of at least 100.degree. C.,
such as at least 125.degree. C., or even at least 145.degree. C.
The exception to this is ultra high molecular weight polyethylene
which has a glass transition temperature of -160.degree. C. and a
melt point of 135.degree. C.
[0026] Returning to FIG. 3, once heated, the extruded thermoplastic
rod is bent, as illustrated at 304. For example, while the
thermoplastic rod is at a temperature greater than the glass
transition temperature, the rod may be bent to a desired shape. In
an example, the rod may be applied between a three-roller system.
In another example, the rod may be bent and placed into a mold. In
a further example, the rod may be clamped to a circular mold and
bent through the rotation of the mold. An exemplary mechanism for
bending the thermoplastic rod is illustrated in FIG. 5, described
in more detail below.
[0027] In a particular example, the rod is a straight rod. Further,
the rod may have a cross-section, such as a circular cross-section
or a polygonal cross-section. In an example, the cross-section is a
polygonal cross-section, such as a polygon with at least four
sides. In particular, the polygon may be a rectangle or square. As
an alternative to heating and bending, an extruded rod may be
extruded in the form of an arc and the ends of the arc joined to
form the sealing device. In another alternative, arcs may be cut
from sheets of material, such as extruded sheets or compression
molded sheets, and the ends of the arcs joined.
[0028] Once bent, the ends of the rod are joined, as illustrated at
306 of FIG. 3. For example, the first and second ends of a rod may
be joined together. In another example, the ends of the rod may be
joined to the respective ends of another rod or other rods. The
ends of the rod may be joined through hot melt welding, injection
molding, adhesive, ultrasonic welding, or any combination thereof.
In a particular example, the ends of the rod are joined through hot
melt welding. For example, the hot melt welding may include
applying a heat source to the ends of the rod to melt portions of
the rod proximal to the ends and once melted, pressing the ends
together. In such an example, the ends of the rod are melted
without melting the whole rod.
[0029] Once joined, the extruded rod forms a semi-finished ring.
The semi-finished ring may be annealed, as illustrated at 308. In
an example, the semi-finished ring is annealed at a temperature
greater than the glass transition temperature of the thermoplastic
material. The semi-finished ring may be annealed for a period of at
least 2 hours. The semi-finished ring may be further machined or
processed to form a seal ring.
[0030] In a further embodiment, FIG. 4 illustrates an exemplary
method 400 that includes heating an extruded rod, as illustrated at
402. For example, the extruded rod may include a thermoplastic
material, such as PEEK. The rod may be a straight rod. In an
example, the PEEK may have a melting point of approximately
343.degree. C. The extruded rod may be heated to a temperature in a
range of 200.degree. C. to 342.degree. C. In a particular example,
the extruded rod is heated in a hot air oven.
[0031] Once heated, the extruded rod may be bent, as illustrated at
404. For example, while the thermoplastic rod is at a temperature
greater than the glass transition temperature, preferably with a
heat index in the range of 0.6 to 0.999, the rod is bent. In a
particular example, the rod may be inserted into a forming machine,
such as the machine illustrated in FIG. 5, and bent into the
desired shape.
[0032] For example, FIG. 5 includes an illustration of an exemplary
forming machine 500. The forming machine 500 includes a circular
mold 502 that pivots about an axis 503. Around the circumference of
the circular mold 502 is a groove 504 for engaging an article 506.
In particular, the article 506 may be clamped into the groove by
clamp 508. In addition, the forming machine 500 may include a set
of rollers 510 distributed around the circumference of the circular
mold 502. An axis of a roller 510 may be attached to trucks that
traverse tracks 512 or guide rods. Accordingly, the rollers 510 may
engage the circular mold 502 or may be disengaged and moved away
from the circular mold 502.
[0033] In use, the clamp 508 secures an article 506 to the circular
mold 502. The circular mold 502 rotates and the clamp 508 rotates
with the circular mold 502, drawing the article 506 around the
circumference of the circular mold 502 and into the groove 504. As
the clamp 508 moves past a roller 510, the roller 510 is engaged
with the article 506 and the circular mold 502, applying radial
force on the article 506. Accordingly, the article 506 is formed
into an arc structure that may be used to form a seal ring. In a
further example, the circular mold 502 may be heated to
conductively heat the article 506. In another example, bending may
be performed in a heated environment, such as an oven.
[0034] Returning to FIG. 4, the bent extruded rod is permitted to
cool, as illustrated at 406. For example, the bent extruded rod may
be cooled to a temperature below a glass transition temperature. In
particular, the bent extruded rod may be allowed to cool to a
temperature near room temperature. In an example, the bent rod is
cooled with forced convection. Subsequently, the bent rod may be
removed from the mold.
[0035] In an example, the thickness of the cross section of the
extruded rod, which becomes the radial thickness once bent, may be
less than 1/5 or 20% of the outside diameter of a circle defined by
the arc of bent extruded rod. For example, the outside diameter of
the circle including an arc defined by the bent rod may be at least
5 times the radial thickness of the rod, such as at least 10 times
the radial thickness, or even at least 20 times the radial
thickness. In a particular embodiment, the radial thickness is at
least 1 inch, such as at least 2 inches.
[0036] The cross-section of the extruded rod may be in the shape of
a circle or in the shape of a polygon. In particular, the polygon
may have at least three sides, such as at least four sides. In an
example, the polygon is four-sided in cross-section, such as a
rectangle or square. In a particular example, the cross-sectional
area of the rod is at least 1 sq. in., such as at least 2 sq. in.,
or even at least 3 sq. in. Further, the cross-sectional area may be
not greater than 50 sq. in.
[0037] In preparation for joining the ends of the rod, the rod may
optionally be dried, as illustrated at 408. For example, the rod
may be heated to a temperature in excess of 100.degree. C. In a
particular example, the rod may be heated to a temperature of at
least about 110.degree. C., such as at least 130.degree. C., or
even at least about 145.degree. C. for a period of at least one
hour, such as at least two hours, or even three hours or more.
Alternatively, the rod may be removed from the mold in a hot state,
but below its glass transition temperature. While the rod is in the
hot state, the ends may be joined, such as through the melt welding
process described below, which serves to maintain the rod in a dry
condition without an additional drying step.
[0038] Once dry, the ends of the extruded rod may be joined, such
as through melt welding. In an example, the ends of the rod are
melted, as illustrated at 410, and pressed together, as illustrated
at 412, to form a semi-finished ring. In an example, the ends are
melted using a heat source. For example, the heat source may be a
contact heat source in which both of the ends contact the heat
source and are melted via conduction. In an example, the contact
heat source is a flat heated plate. In another example, the heat
source may be a non-contact heat source, such as a radiant heat
source or convective heat source. Alternatively, the ends may be
joined using techniques, such as radiofrequency techniques
including microwave techniques, inductive techniques, laser
techniques, or any combination thereof.
[0039] FIG. 10 and FIG. 6 include illustrations of an exemplary
heat welding apparatus. For example, as illustrated in FIG. 10, the
heat welding apparatus 600 may include a pair of fixtures 602 and
604 for securing respective ends 606 and 608 of a bent
thermoplastic rod. The fixtures 602 and 604 may be guided in a path
along rails 610 and 612 to motivate the ends 606 and 608 towards
one another. The fixtures 602 and 604 may be motivated along rails
610 and 612 by drive mechanisms 614 and 616. In an example, the
drive mechanisms 614 and 616 may be servo motors with load cells to
control the force supplied to the ends 606 and 608. Alternatively,
the drive mechanisms 614 and 616 may include hydraulic,
electromechanical, inductive, pneumatic, or other motivating
devices. In addition, the welding apparatus 600 may include an arm
622 that extends to an outer diameter of the ring at a location
620. The arm 622 may constrain the outer diameter of the ring, for
example, to form a circular shape in contrast to an ovular or egg
shape. For example, the arm 622 may apply a radial force to the
ring, such as a force directed toward a radial center of the ring.
Alternatively, more than one arm may be used to constrain the
diameter of the ring to form a desired shape, such as a circular
ring, an ovular ring, or an egg-shaped ring.
[0040] The heat welding apparatus 600 may also include a heater
618. In use, the heater 618 may be moved into the path of the ends
606 and 608. In the case of a contact heater, the ends 606 and 608
may be motivated to contact either side of the heater 618 to melt
the ends 606 and 608. In another example, the heater 618 may be a
non-contact heater. An exemplary non-contact heater is illustrated
in FIG. 6. For example, the non-contact heater 700 may include a
heat source 702, such as a radiant heat source or a convective heat
source. In an embodiment, the heat source 702 is separated from the
ends 606 and 608 by a plate 708. The ends are placed in proximity
to the plate 708 and heated to form a melted area with a flat
interface between the melted and unmelted portions of the ends 606
and 608. In an example, the plate 708 does not include an opening
or cavity. In the illustrated embodiment, the non-contact heater
700 may optionally include a cavity or opening 704. Optionally, the
heater 700 may include a lip 706 surrounding the cavity or opening
704. A similar cavity or opening to that of the cavity or opening
704 may be located on an opposite side of the heater 700.
Alternatively, more than one heat source with a cavity or opening
may be used to melt the ends 606 and 608.
[0041] In use, the ends 606 and 608 may be placed in proximity to
the plate 708 or if present, optionally inserted into a cavity or
opening 704 of the heater 700. The ends 606 and 608 do not contact
the heat source 702. For example, the ends 606 and 608 may be
disposed at a position less than 5 mm from the heat source 702,
such as not greater than 2 mm, or even not greater than 1 mm from
the heat source 702. Once melted, the ends 606 and 608 are
withdrawn from the cavity or opening 704, if present. The heater
618 is removed from the path of the rods 606 and 608, and the rods
606 and 608 are pressed together by fixtures 602 and 604 motivated
by drive mechanisms 614 and 616. Arms may be used to constrain the
outer diameter of the ring during the welding process.
[0042] Returning to FIG. 4, the ends of the extruded rod may be
pressed together at a pressure of at least 50 psi. For example, the
pressure may be at least 75 psi, such as at least 100 psi. In a
particular embodiment, the use of a non-contact heat source and
desirable pressures results in an essentially void free weld having
desirable strength and durability. For example, the ends may be
pressed together with enough force to extrude a portion of the
material from between the ends of the rod. In an example, a
sufficient portion of both ends of the rod are melted and the ends
of the rod are pressed together with enough force to extrude
material equivalent to at least 1/8'' of the rod for each 1 sq.
inch of rod cross-section. For example, the ends may be pressed
together to extrude at least 1/4'' of the rod for each 1 sq. inch
of rod cross-section, such as at least 1/2'' of the rod per 1 sq.
inch of rod cross-section. Maintaining a higher pressure in the
melt than the surrounding environment during welding may reduce
voids. Other methods to maintain a higher pressure include lowering
the surrounding pressure by welding in a vacuum environment or
constraining the ability of the molten material to extrude from
between the melted ends as they are pushed together. In particular,
such methods provide a void-free weld, defined as a weld free of
voids having a longest dimension greater than 0.4 mm.
[0043] Once welded, the semi-finished ring may be annealed, as
illustrated at 414. For example, the semi-finished ring may be
annealed at a temperature greater than the glass transition
temperature of the extruded thermoplastic material for a period of
at least two hours, such as at least four hours, or even at least
six hours. In a particular example, the semi-finished ring may be
dried, for example, at a temperature greater than 100.degree. C.,
such as a temperature greater than 120.degree. C., for a period of
at least one hour, such as at least two hours. The temperature may
be ramped to the annealing temperature at a rate in a range of
5.degree. C. per hour to 15.degree. C. per hour, such as 8.degree.
C. per hour to 12.degree. C. per hour. In particular, the annealing
temperature may be at least 1.2 times the glass transition
temperature, such as at least 1.5 times, or even at least 1.7 times
the glass transition temperature, providing the melting point is
not exceeded. Once the annealing temperature is reached, the
temperature may be maintained for a period of at least two hours,
such as at least four hours, at least six hours, or even eight
hours or more. The ring may then be cooled at a controlled rate,
such as a rate in a range of 5.degree. C. per hour to 15.degree. C.
per hour, such as a range of 8.degree. C. per hour to 12.degree. C.
per hour, to a temperature of less than the glass transition
temperature. The semi-finished ring may then be allowed to cool to
room temperature. In an example, the ring is left in the oven while
the oven is off until room temperature is reached.
[0044] As illustrated at 416, burs or melt flow may be trimmed from
the outer surface following annealing. For example, the burs or
melt flow from the welds may be abraded or cut from the
semi-finished ring. Alternatively, the burs or melt flow may be
abraded or cut prior to annealing. Further, the semi-finished ring
may be machined to form a seal ring.
[0045] In addition, the method of FIG. 4 may include trimming the
ends of the rod prior to joining the ends. For example, the bent
rod may be cut to a uniform arc and the arc used with other arcs to
form the seal ring. FIG. 7 includes an illustration of an exemplary
template 800 for cutting rods. In an example, the template 800
includes a fixture 802 for securing the rod. The fixture 802 may be
secured by mounts 808. Further, the template 800 may include a cut
groove 804 along which a cut may be made. Optionally, the template
800 may include a distance groove 806 or guide on which a cutting
mechanism may be secured to ensure a straight cut through the cut
groove 804. In use, a bent rod may be placed into fixture 802. A
cutting mechanism, such as a saw or rotating abrasive wheel, may be
guided through the cut groove 804 to form uniform arcs and uniform
ends to the arcs.
[0046] As a result, seal rings with desirable properties may be
formed of engineered thermoplastics. In particular, seal rings
formed through such methods may have desirable mechanical
properties in addition to being of large circumference and
diameter. For example, the above method is particularly useful in
forming seal rings having a circumference of at least 0.62 meters,
such as at least 1.0 meters, at least 1.5 meters, at least 2.0
meters, at least 4.1 meters, at least 4.5 meters, or even at least
4.8 meters. In a particular embodiment, the method may be used to
form a seal ring having a diameter of at least 0.2 meters from a
thermoplastic material. For example, the seal ring may have a
diameter of at least 0.47 meters, such as at least 1.0 meters, at
least 1.3 meters, at least 1.45 meters, or even at least 1.55
meters. In addition or in an alternative embodiment, the seal ring
may have a diameter of not greater than 3.0 meters.
[0047] The seal ring may be formed of an engineered thermoplastic
material that has desirable properties. For example, the
thermoplastic rod may be formed of a thermoplastic material, such
as an engineering or high performance thermoplastic polymer. For
example, the thermoplastic material may include a polymer, such as
a polyketone, polyaramid, a thermoplastic polyimide, a
polyetherimide, a polyphenylene sulfide, a polyethersulfone, a
polysulfone, a polyphenylene sulfone, a polyamideimide, ultra high
molecular weight polyethylene, a thermoplastic fluoropolymer, a
polyamide, a polybenzimidazole, a liquid crystal polymer, or any
combination thereof. In an example, the thermoplastic material
includes a polyketone, a polyaramid, a polyimide, a polyetherimide,
a polyamideimide, a polyphenylene sulfide, a polyphenylene sulfone,
a fluoropolymer, a polybenzimidazole, a derivation thereof, or a
combination thereof. In a particular example, the thermoplastic
material includes a polymer, such as a polyketone, a thermoplastic
polyimide, a polyetherimide, a polyphenylene sulfide, a polyether
sulfone, a polysulfone, a polyamideimide, a derivative thereof, or
a combination thereof. In a further example, the thermoplastic
material includes polyketone, such as polyether ether ketone
(PEEK), polyether ketone, polyether ketone ketone, polyether ketone
ether ketone ketone, a derivative thereof, or a combination
thereof. An example thermoplastic fluoropolymer includes
fluorinated ethylene propylene (FEP), polytetrafluoroethylene
(PTFE), polyvinylidene fluoride (PVDF), perfluoroalkoxy (PFA), a
terpolymer of tetrafluoroethylene, hexafluoropropylene, and
vinylidene fluoride (THV), polychlorotrifluoroethylene (PCTFE),
ethylene tetrafluoroethylene copolymer (ETFE), ethylene
chlorotrifluoroethylene copolymer (ECTFE), or any combination
thereof. An exemplary liquid crystal polymer includes aromatic
polyester polymers, such as those available under tradenames
XYDAR.RTM. (Amoco), VECTRA.RTM. (Hoechst Celanese), SUMIKOSUPER.TM.
or EKONOL.TM. (Sumitomo Chemical), DuPont HX.TM. or DuPont
ZENITE.TM. (E.I. DuPont de Nemours), RODRUN.TM. (Unitika),
GRANLAR.TM. (Grandmont), or any combination thereof. In an
additional example, the thermoplastic polymer may be ultra high
molecular weight polyethylene. In addition, the seal ring may be
formed of a composite material including a thermoplastic material
and a filler, such as a fluoropolymer, a solid lubricant, or a
combination thereof.
[0048] The thermoplastic material may have a melting point of at
least 250.degree. C. For example, the melting point may be at least
300.degree. C., such as at least 320.degree. C. In addition, the
thermoplastic material may have a desirably high glass transition
temperature, such as a glass transition temperature of at least
100.degree. C. For example, the glass transition temperature may be
at least 125.degree. C., such as at least 145.degree. C.
[0049] In a further example, the seal ring may have a coefficient
of friction of not greater than 0.45. For example, the coefficient
of friction may be not greater than 0.4, such as not greater than
0.35, or even not greater than 0.3. In particular, the coefficient
of friction may be not greater than 0.2, such as not greater than
0.1.
[0050] Further, the thermoplastic material may have desirable
mechanical properties. For example, the thermoplastic material may
have a tensile strength at yield of at least 3,100 psi (21.4 MPa),
such as at least 10,000 psi (68.9 MPa), or even at least 15,000 psi
(103 MPa). In a further example the thermoplastic material may have
a tensile modulus of at least 100 ksi (0.69 GPa), such as at least
750 ksi (5.16 GPa), at least 850 ksi (5.86 GPa), or even at least
1000 ksi (6.89 GPa). Further, the welded thermoplastic material may
have a desirable weld elongation-at-break. For example, the weld
elongation-at-break may be at least 5%, such as at least 7%, at
least 10%, at least 15%, at least 20%, or even at least 30%. Weld
elongation-at-break is determined through tensile testing of welded
samples according to ASTM D638. The welded samples may or may not
be annealed.
[0051] In an example in which the seal is formed of a composite
material including the thermoplastic material and at least a
fluoropolymer dispersed within the thermoplastic material, the
composite material may have a weld elongation-at-break of at least
3%. For example, the weld elongation-at-break may be at least 5%,
such as at least 8%, at least 10%, at least 15%, or even at least
18%. In an example, the weld tensile strength is at least 40 MPa,
such as at least 50 MPa, at least 60 MPa, or even at least 70 MPa.
In particular, the weld tensile strength of the composite is at
least 50% of the weld tensile strength of the unfilled material,
such as at least 60%, or even at least 70% of the weld tensile
strength of the unfilled material.
[0052] As described in relation to FIG. 1 and FIG. 2, the seal ring
may include a weld. Depending upon the size of the ring and the
number of joints used to form the ring, the seal ring may include
more than one weld, such as two welds, or even three welds or
more.
[0053] The exemplary weld method can also be used to weld arcs of
extruded or compression molded thermoplastics that are cut from a
plate to create a semi-finished ring with desirable properties
after annealing. While welding is used herein to specifically
denote a method of heating ends of rods and pressing the ends
together, other joining techniques may be used to join the ends of
rods. For example, other joining techniques may include
injection-molding to join ends, ultrasonic treating, induction
heating, or an irradiative techniques, such as a laser or a
microwave technique. The adjoined ends formed through welding are
referred to herein as a weld and the adjoined ends formed through
welding or another joining technique is referred to herein as a
joint.
[0054] In addition, the welding or joining of arcs or portions can
be used to form circular, ovular, polygonal or complex shaped
seals. For example, the seal can have a polygonal shape, such as a
triangle, square, rectangle, pentagon, hexagon, heptagon, octagon,
or any combination thereof. The polygon may have at least four
sides, such as at least 6 sides, at least 8 sides, or even at least
10 sides. In another example, a complex shape can be a FIG. 8,
irregular polygons, or other complex shapes. In particular, the
shapes may be closed. Alternatively, the shapes may be open, having
one or more breaks along their extent.
[0055] Particular embodiments of the above-described method provide
technical advantages over conventional techniques. While reducing
waste, such present embodiments also enable the production of large
size seal rings of thermoplastic material having desirable
mechanical properties. In particular, the present embodiments
provide for seal rings having a circumference of at least 1.5
meters or a largest diameter of greater than 1.3 meters with
desirable elongation-at-break properties. Such properties are
indicative of durability and suitability as a seal ring. Moreover,
such methods provide for seal rings formed of engineering
thermoplastic materials that typically have greater glass
transition temperatures and melt temperatures and
characteristically have high modulus and high tensile strength. In
addition, such thermoplastic engineering thermoplastic materials
have desirable coefficients of friction.
[0056] In particular, the above methods permit the formation of
large circumference seal rings from extruded rods of desirable
materials. Conventional techniques for forming seal rings are
limited in diameter or limited in material of use. Conventional
techniques based on cutting seal rings from extruded sheets suffer
from limits to seal diameter and suffer from variability between
properties in the machine and transverse directions being
transferred to the seal ring. Typically it is difficult to extrude
suitable thermoplastics in sheets greater than 1 meter.
Conventional compression molding techniques are limited in the
material of use and provide poor mechanical properties. In
contrast, the present methods provide a ring that can be used with
a variety of materials, provides for a seal ring whose properties
in the circumferential direction are related to machine direction
properties of the extruded rod, and has desirable durability and
mechanical properties.
[0057] Further, particular embodiments of fluoropolymer filled
composite material are adapted for use in the above methods. For
example, particular fluoropolymer filler permits welding of the
seal ring to produce a desirable weld elongation-at-break, whereas
other filled composites provide for less desirable weld
elongation-at-break.
Examples
Example 1
[0058] Four PEEK rods are heated to different temperatures
(150.degree. C., 200.degree. C., 285.degree. C., and 310.degree.
C.) and are formed around a steel wheel. The formability of the
heated PEEK rods is measured as the distance between the two ends
of the 34 inch rod while it is tightly wound around the 15.5 inch
diameter steel wheel. Table 1 illustrates the formability.
TABLE-US-00001 TABLE 1 Formability of Thermoplastic Rods
Temperature (.degree. C.) Formability (in) 150 NF 200 17.0 285 16.7
310 16.5 NF--Not Formable
[0059] The rod that is heated to 150.degree. C. is too rigid to
form. With increasing temperature, flexibility of the PEEK rod
increased. Around 310.degree. C., the PEEK rod has relatively high
formability.
Example 2
[0060] Three PEEK rods are heated to 310.degree. C. and are formed
around a steel wheel. The arcs are removed from the wheel when the
core temperatures reached a specified temperature. The relaxation
of the cooled PEEK arc is measured to determine spring-back. As
illustrated in Table 2, PEEK rods spring-back significantly when
removed from the wheel at temperatures above the glass transition
temperature of PEEK. When removed below the glass transition
temperature, the PEEK arcs show similar and relatively low
spring-back.
TABLE-US-00002 TABLE 2 Spring-back of Thermoplastic Rods
Temperature (.degree. C.) Spring-Back (in) 200 3 125 0.25 22
0.25
Example 3
[0061] Fourteen 4''.times.1''.times.1'' extruded PEEK bars
available from McMaster-Carr are used to prepare seven welded bars
by contact hot plate welding. One sample is formed after drying at
90.degree. C. for 3 hours before welding. The remaining samples are
formed from rods that are dried at temperatures in the range of
135.degree. C. to 190.degree. C. for 2 hours.
[0062] The samples are prepared by heating rod ends with a heater
temperature in the range of 385.degree. C. to 450.degree. C. and
contacting the rods ends together at a pressure of 100 psi. The
samples are machined for tensile testing. In addition, some of the
samples are annealed at temperatures of 250.degree. C. for a period
of 4 hours. The samples are compared to an extruded sample
available from McMaster-Carr and an extruded control available from
Ensinger. Table 3 illustrates the elongation-at-break properties
for the samples.
TABLE-US-00003 TABLE 3 Elongation-at-break for Welded Samples
Sample (weld temp., weld time) Avg. Elongation-at-break (%)
Extruded 28 Unannealed Extruded 22 Annealed Extruded 23 Unannealed
420.degree. C., 40 s 9 Annealed 420.degree. C., 20 s 13 Unannealed
445.degree. C., 40 s 7 Annealed 445.degree. C., 40 s 12 Annealed
385.degree. C., 20 s 3 Annealed 450.degree. C., 20 s 9
[0063] The extruded PEEK from McMaster-Carr exhibits poor
elongation-at-break when compared with extruded PEEK available from
Ensinger. Welded PEEK samples generally exhibit lower
elongation-at-break compared to unwelded references. Annealed
samples exhibit improved elongation-at-break over unannealed
samples.
[0064] When elongation-at-break values are evaluated as a function
of hot plate temperature and heat time during welding, both hot
plate temperature and heat time influence mechanical performance.
Table 4 illustrates the elongation-at-break properties. Comparing
the samples at a hot plate temperature of 385.degree. C. and heat
times of 20 s, 40 s, and 60 s, the heating time of 40 s provided an
elongation-at-break of 13% for the annealed sample. Heating at 60 s
provided similar results.
TABLE-US-00004 TABLE 4 Elongation-at-break (%) for Samples Contact
Time (s) Temp. (.degree. C.) 20 s 40 s 60 s 445 9 11 420 13 385 3
13 12
[0065] As a function of temperature, the 420.degree. C. sample
exhibits desirable elongation-at-break, even for samples with short
heat times. At 20 s, the hot plate temperature of 420.degree. C.
provides higher elongation-at-break values than a hot plate
temperature of 385.degree. C. and 445.degree. C. Accordingly,
385.degree. C. appears to be too low to affect adequate bonding and
445.degree. C. appears to be too hot, potentially degrading the
material.
Example 4
[0066] Samples are formed from extruded PEEK available from
Ensinger. Welding is performed using hot plate contact welding and
hot plate non-contact welding. The extruded PEEK bars are dried at
150.degree. C. for two and a half hours.
[0067] Welding is performed with a hot plate at a temperature in
the range of 400.degree. C. and 420.degree. C. Contact welding
includes contacting rod ends with the hot plate for a period in the
range of 40 s to 60 s. Non-contact welding is carried out with the
hot plate at 500.degree. C. with a dwell time of 240 s. During
heating, the non-contact rod ends are held 1 mm to 2 mm from the
plate. Once melted, the ends are pressed together to form the
samples.
[0068] The hot plate contact samples are annealed at a temperature
around 250.degree. C. for a period between 4 hours and 8 hours.
Table 5 illustrates the elongation-at-break.
TABLE-US-00005 TABLE 5 Affect of Annealing on Mechanical Properties
Annealing Avg. Elongation-at-break (%) Non-contact Control 12
Control 18 250.degree. C., 4 hours 13 250.degree. C., 8 hours 33
300.degree. C., 4 hours 19
[0069] Based on the illustrated elongation-at-break, annealing at
250.degree. C. for a period of 8 hours appears to provide desirable
elongation-at-break properties. Other annealing periods and
temperatures provided lower elongation-at-break values.
Example 5
[0070] Extruded PEEK samples are welded. The samples are dried at a
temperature of 150.degree. C. for three hours. Welding is performed
at plate temperatures of 420.degree. C. for a period of 40 s. The
ends are pressed together at a pressure of 100 psi. All welds are
annealed at 250.degree. C. for a period of 8 hours. The samples are
machined for tensile testing. Table 6 illustrates the average
elongation-at-break and distribution of results.
TABLE-US-00006 TABLE 6 Mechanical Properties of Welded PEEK
420.degree. C., 40 s 420.degree. C., 60 s Avg. Elongation (%) 37.19
37.05 % Samples >20% Elongation 35 43
Example 6
[0071] In accordance with the above examples, samples are formed
from dried extruded PEEK available from one of Ensinger or
Quadrant. The sample ends are heated at 420.degree. C. for at least
40 s and pressed together for a period of at least 40 s. The
samples are annealed at a temperature of 250.degree. C. for a
period of 8 hours. The samples are machined for mechanical property
testing. Table 7 illustrates the elongation-at-break for the
samples in a procedure that conforms to ASTM D638.
TABLE-US-00007 TABLE 7 Elongation-at-break for Welded PEEK
Materials Mean Elongation-at-break (%) Control Contact Non-Contact
Ensinger 14.24 18.77 22.46 Quadrant 19.35 33.88 38.44
Example 7
[0072] During the experiments performed in relation to the other
examples, Applicants noted that early failure tended to be
attributable to voids near the welded surfaces. Samples are made in
a manner similar to that of Example 5. The melted ends of the rods
are pressed together at a pressure of at least 50 psi. Material in
an amount equivalent to at least 1/8'' of the rod length per square
inch of cross-section extrudes from between the rods when they are
pressed together. CT scans illustrate that the extruded material
removes the voids, leaving a low void bond. Other methods to
maintain a higher pressure within the melt than the surrounding
pressure include lowering the surrounding pressure by welding in a
vacuum environment or constraining the ability of the molten
material to extrude from between the melted ends as they are pushed
together.
Example 8
[0073] A grade of extruded PEEK with excellent properties for a
seal comprises 15% PTFE. It has the following properties as an
extruded rod.
TABLE-US-00008 TABLE 8 Properties of PTFE-filled PEEK Extruded Rod
ASTM Property No. US Value SI Unit General Form -- Pellets Pellets
(Gray) (Gray) Composition -- PTFE filled PTFE filled
(Polyetherketoneketone) Filler Content (Nominal value) -- 15% 15%
Specific Gravity D792 1.39 1.39 g/ml Linear Mold Shrinkage, in/in
D955 0.01 0.01 cm/cm Moisture Absorption @24 hr., % D570 0.1
0.10%.sup. Mechanical Tensile Strength (Break), ksi D638 12 83 MPa
Tensile Modulus, Mpsi D638 0.5 3.4 GPa Elongation (Break), % D638
15 15% Flexural Strength (Yield) ksi D790 21 144 MPa Flexural
Modulus Mpsi D790 0.5 3.4 GPa Izod, Notched, ft-lb/in @1/8'' D256
0.8 0.6 J/cm Hardness, Shore D D2240 85 85 Thermal Melting Point,
.degree. F. DSC 650 343.degree. C. Tg (Glass Transition), .degree.
F. DSC 290 143.degree. C. Flammability Rating (UL 94) UL94 V-0 V-0
HDT@264 psi, .degree. F. D648 340 171.degree. C. Other Kinetic
Coefficients of Friction D1894 0.1 0.1 Static Coefficients of
Friction D1894 0.1 0.1
[0074] An extruded rod of 25% PTFE-filled PEEK composite also has
an acceptable elongation-at-break of 10% and a low coefficient of
friction.
[0075] A third composite contains 10% carbon black-filled PEEK. It
has a desirable elongation-at-break while providing the PEEK with
static dissipative properties.
Example 9
[0076] Extruded PEEK samples are welded. As indicated, a subset of
the samples is dried at a temperature of 150.degree. C. for three
hours. Welding is performed at plate temperatures of 420.degree. C.
for a period of between 40 s and 60 s. The ends are pressed
together. As indicated, a subset of the samples is annealed at
250.degree. C. for a period of 8 hours. The samples are machined
for tensile testing.
[0077] Samples are tested using Computed Tomography (CT) scanning
and ultrasonic scanning The CT scanning is performed with the
parameters 150 kV, 50 mA, 30 micrometer Voxel, 800 images, and 1
sec time. Ultrasonic scanning is performed by ultrasonic NDT with a
transducer frequency of 50 MHz.
[0078] A comparison of void detection by the scanning techniques is
illustrated in Table 9. As illustrated, CT detects voids near the
surface and voids having a size less than 0.38 mm. Ultrasonic
scanning is less effective at detecting voids near the surface or
having a size less than 0.38 mm. Typically, seals are machined,
removing voids near the surface and a limited number of voids of
size less than 0.4 mm have little influence on performance, such as
elongation and tensile strength.
TABLE-US-00009 TABLE 9 Void Detection Using Scanning Techniques
Void Size, Ultrasonic CT Reference mm (if any) NDT Results No
Pre-drying, Normal Anneal 0.38, Surface No Voids Voids No
Pre-drying, Normal Anneal -- No Voids No Voids Pre-dried, Normal
Anneal Large Voids Voids Voids Pre-dried, Normal Anneal Large
Voids, Voids Voids Surface No Pre-Drying, Not Annealed 0.7 mm, No
Voids Voids Surface Pre-dried, Not Annealed -- No Voids No
Voids
[0079] Samples similar to the above samples are tested for
elongation and tensile properties. As illustrated in Table 10, the
average sample absent voids exhibits a large elongation, whereas
samples having voids detectable by Ultrasonic NDT failed at the
weld and exhibit no or little elongation.
TABLE-US-00010 TABLE 10 Elongation Properties for Samples Sample
Elongation (%) Average (Weld 420.degree. C., 40 s) 37.19 Average
(Weld 420.degree. C., 60 s) 37.05 Surface Porosity (Weld
420.degree. C., 60 s) 7.22 Surface Porosity (Weld 420.degree. C.,
40 s) 5.34 Subsurface Porosity (Weld 420.degree. C., 60 s) 2.57
[0080] As illustrated in Table 10, the average elongation for the
samples is significantly greater than 20%. When voids are present,
either at the surface or under the surface, the elongation drops
significantly.
[0081] In an example, a method of testing voids includes
determining settings of an ultrasonic scanning device based on
comparative testing relative to another scanning technique, such as
CT scanning For example, a set of samples including a variety of
void conditions or types can be scanned using a CT technique and an
ultrasonic technique. The samples can be tested for a property,
such as a mechanical property, for example, tensile strength or
elongation, to determine what constitutes a significant defect or a
defect having an influence on the property. Desirable parameters
for the ultrasonic scanning technique can be determined that result
in detection of the significant defect, while having limited
success for detecting insignificant defects.
[0082] In a particular embodiment, a method of forming a seal ring
includes heating a thermoplastic rod to a temperature above a glass
transition temperature. The thermoplastic rod has first and second
ends. The method further includes bending the thermoplastic rod
into a circular structure while the temperature is above the glass
transition temperature, joining the first and second ends of the
thermoplastic rod to form a semi-finished ring, and annealing the
semi-finished ring.
[0083] In an embodiment, a method of forming a seal ring includes
heating an extruded rod to a temperature above a glass transition
temperature. The extruded rod has first and second ends. The method
further includes bending the extruded rod into a circular structure
while the temperature is above the glass transition temperature,
joining the first and second ends of the extruded rod to form a
semi-finished ring, and annealing the semi-finished ring.
[0084] In another exemplary embodiment, a method of forming a seal
ring includes heating an extruded rod to a temperature above a
glass transition temperature of a material of the extruded rod. The
extruded rod has first and second ends. The method further includes
bending the extruded rod while the temperature is above the glass
transition temperature, cooling the bent extrude rod to a
temperature below the glass transition temperature, melt welding
the first and second ends of the extruded rod to form a
semi-finished ring, and annealing the semi-finished ring.
[0085] In a further exemplary embodiment, a method of forming a
seal ring includes heating first and second extruded rods to a
temperature above a glass transition temperature and below a
melting point of a material of the extruded rods. The extruded rods
have first and second ends. The method further includes bending the
extruded rods while the temperature is above the glass transition
temperature, joining the first ends of the first and second
extruded rods and the second ends of the first and second extruded
rods to form a semi-finished ring, and annealing the semi-finished
ring.
[0086] In a further exemplary embodiment, a method of forming a
seal ring includes cutting arcs from a compression molded or
extruded sheet. The arcs have first and second ends. The method
further includes joining the first ends of the first and second
arcs and the second ends of the first and second arcs to form a
semi-finished ring, and annealing the semi-finished ring.
[0087] In an additional embodiment, an apparatus includes a
circular mold comprising a groove disposed around the circumference
of the circular mold. The circular mold is to pivot around a
central point. The apparatus also includes a clamp to secure an
article in the groove of the circular mold. The clamp is configured
to follow the pivoting motion of the circular mold. The apparatus
further includes a plurality of rollers distributed around the
circumference of the circular mold. Each roller of the plurality of
rollers is configured to engage and apply radial force to the
article after the clamp passes the position of the each roller.
[0088] In another exemplary embodiment, a seal ring includes a
thermoplastic material having a weld elongation-at-break of at
least 5%. The seal ring has a diameter of at least 1.3 meters.
[0089] In a further exemplary embodiment, a seal ring has a weld
and includes a thermoplastic material having a glass transition
temperature of at least 100.degree. C. The thermoplastic material
has a weld elongation-at-break of at least 5%. The seal ring has a
diameter of at least 1.3 meters. The seal ring has a coefficient of
friction of not greater than 0.45.
[0090] In an additional embodiment, a seal ring includes extruded
PEEK material having a weld elongation-at-break of at least 5%. The
seal ring has a diameter of at least 1.3 meters.
[0091] In a further embodiment, an apparatus includes a first
fixture to engage a first end of a thermoplastic arc member and a
second fixture to engage a second end of the thermoplastic arc
member. The first and second fixtures motivate the first and second
ends along a path in relative motion toward one another. The
apparatus also includes a heater including a heat source. The
heater is configured to move into the path. The first and second
fixtures move the first and second ends into proximity to the heat
source without contacting the heat source. The first and second
ends at least partially melt. The first and second fixtures are to
motivate the first and second at least partially melted ends into
contact with each other.
[0092] In a first embodiment, a seal ring includes a weld and a
thermoplastic material a weld elongation-at-break of at least 3%.
In an example of the first embodiment, the seal ring has a
circumference of at least 0.62 meters, such as a circumference of
at least 1.5 meters. In another example, the seal ring has a
diameter of at least 0.2 meters, such as 1.3 meters.
[0093] In a further example, the thermoplastic material is selected
from the group consisting of a polyketone, polyaramid, polyimide,
polyetherimide, polyamideimide, polyphenylene sulfide, polysulfone,
thermoplastic fluoropolymer, a derivation thereof, and a
combination thereof. For example, the thermoplastic material may be
selected from the group consisting of a polyketone, a polyaramid, a
polyimide, a polyetherimide, a polyamideimide, a polyphenylene
sulfide, a polyphenylene sulfone, a fluoropolymer, a
polybenzimidazole, a liquid crystal polymer, a derivation thereof,
or a combination thereof. In another example, the thermoplastic
material is a polyketone material selected from the group
consisting of polyether ether ketone, polyether ketone, poly ether
ketone ketone, a derivation thereof, and a combination thereof. In
an additional example, the thermoplastic material comprises ultra
high molecular weight polyethylene.
[0094] In a particular example, the seal ring has a coefficient of
friction of not greater than 0.45, such as not greater than 0.35.
The thermoplastic material may have a melting point of at least
250.degree. C., such as at least 300.degree. C., or even at least
320.degree. C. The thermoplastic material may have a glass
transition temperature of at least 100.degree. C., such as at least
125.degree. C., or even at least 145.degree. C.
[0095] In an additional example of the first embodiment, the
thermoplastic material has a tensile strength of at least 3100 psi,
such as at least 10000 psi, or even at least 15000 psi. The
thermoplastic material may have a tensile modulus of at least 100
ksi, such as at least 750 ksi, or even at least 850 ksi.
[0096] In another example of the first embodiment, the weld
elongation-at-break is at least 5%, such as at least 10%, at least
15%, or even at least 20%.
[0097] In an example of the first embodiment, the seal ring has a
radial thickness not greater than 20% of the diameter. Further, the
seal ring may have a cross-section in the shape of a polygon, such
as a polygon having at least four sides.
[0098] In an additional example, the thermoplastic material may
include a solid lubricant filler, such as PTFE or carbon black.
[0099] In a second embodiment, a seal ring has a weld and comprises
a thermoplastic material having a glass transition temperature of
at least 100.degree. C. The thermoplastic material with the weld
has a weld elongation-at-break of at least 3%. The seal ring has a
circumference of at least 0.62 meters. The seal ring has a
coefficient of friction of not greater than 0.45. In an example of
the second embodiment, the coefficient of friction is not greater
than 0.4, such as not greater than 0.35.
[0100] In a further example of the second embodiment, the weld
elongation-at-break is at least 5%, such as at least 10%, at least
15%, or even at least 20%. The thermoplastic material may have a
tensile modulus of at least 100 ksi. In an example, the glass
transition temperature is at least 125.degree. C., such as at least
145.degree. C.
[0101] In a third embodiment, a seal ring includes extruded PEEK
material having a weld elongation-at-break of at least 3%. The seal
ring has a circumference of at least 1.5 meters. In an example of
the third embodiment, the extruded PEEK material is a composite
material comprising a filler. For example, the filler may include a
solid lubricant, such as PTFE. In another example, the filler
includes a ceramic or mineral. In an additional example, the filler
include carbon black.
[0102] In a further example of the third embodiment, the weld
elongation-at-break is at least 5%, such as at least 10%, at least
15%, or even at least 20%. In addition, the seal ring may further
include a weld.
[0103] In a fourth embodiment, a seal ring has a joint and includes
a composite material including a thermoplastic material and a solid
lubricant. The composite material with the joint has a weld
elongation-at-break of at least 3%. The seal ring has a coefficient
of friction of not greater than 0.45.
[0104] Note that not all of the activities described above in the
general description or the examples are required, that a portion of
a specific activity may not be required, and that one or more
further activities may be performed in addition to those described.
Still further, the order in which activities are listed are not
necessarily the order in which they are performed.
[0105] In the foregoing specification, the concepts have been
described with reference to specific embodiments. However, one of
ordinary skill in the art appreciates that various modifications
and changes can be made without departing from the scope of the
invention as set forth in the claims below. Accordingly, the
specification and figures are to be regarded in an illustrative
rather than a restrictive sense, and all such modifications are
intended to be included within the scope of invention.
[0106] As used herein, the terms "comprises," "comprising,"
"includes," "including," "has," "having" or any other variation
thereof, are intended to cover a non-exclusive inclusion. For
example, a process, method, article, or apparatus that comprises a
list of features is not necessarily limited only to those features
but may include other features not expressly listed or inherent to
such process, method, article, or apparatus. Further, unless
expressly stated to the contrary, "or" refers to an inclusive-or
and not to an exclusive-or. For example, a condition A or B is
satisfied by any one of the following: A is true (or present) and B
is false (or not present), A is false (or not present) and B is
true (or present), and both A and B are true (or present).
[0107] Also, the use of "a" or "an" are employed to describe
elements and components described herein. This is done merely for
convenience and to give a general sense of the scope of the
invention. This description should be read to include one or at
least one and the singular also includes the plural unless it is
obvious that it is meant otherwise.
[0108] Benefits, other advantages, and solutions to problems have
been described above with regard to specific embodiments. However,
the benefits, advantages, solutions to problems, and any feature(s)
that may cause any benefit, advantage, or solution to occur or
become more pronounced are not to be construed as a critical,
required, or essential feature of any or all the claims.
[0109] After reading the specification, skilled artisans will
appreciate that certain features are, for clarity, described herein
in the context of separate embodiments, may also be provided in
combination in a single embodiment. Conversely, various features
that are, for brevity, described in the context of a single
embodiment, may also be provided separately or in any
subcombination. Further, references to values stated in ranges
include each and every value within that range.
* * * * *